ADVANCEPRAISEFOR

MasonryHeaters

“InMasonryHeaters,arichandwonderfulbook,KenMateszsweepsawaytheashesofourignoranceabouttherightrelationshiptofire.Heargues—withquietandcrystal-clearclarity—thatmasonryheatersarethemostintelligent,gentle,efficient,environmentallyfriendlyandsustainable,beautiful,andhealthyformofheatinghumanshaveeverknown.ThereismoreknowledgeandtruthaboutmasonryheatersbetweenthesetwocoversthanhaseverbeforebeenpublishedinEnglish.”

—ALBIEBARDEN,MaineWoodHeatCompany

“Thisbookisajoy!KenMateszguidesusonaclearpaththroughthewoodstogettinganheirloommasonryheater,andoffersinvaluableinformationonwhyweshouldwanttotraverseit.Readerswilllearnaboutmuchmorethanjustmasonryheatersalongthejourney,however,includinghowtheirhouseworks(orshouldwork),andhowtohavetheirownradiatingenergysourceatitscenter—includingexactlywhatittakestogettheirmasonryheaterdesigned,built,andburning.Nottomentionsomewonderfulstoriesaboutthepeoplewhohavemademasonryheatersapartoftheirlives!Maythesunshineonthisbook.”

—TIMOTHYSEATON,President,TheAllianceofMasonryHeaterandOvenProfessionals

“Thisbookshouldbeontherequiredreadinglistforanyonewantingtobecomeaheatermason,orforanyoneplanningtoinstallandheatwithamasonryheater.Mateszhascapturedthetruebeautyanduser-friendlinessoftheseexquisiteheaters,and,withease,helpsguidereadersthroughtheprocessofdesigningabeautiful,andfunctional‘pieceofthesun’fortheirhomes.Ihighlyrecommendthebook,aswellasmasonryheaters.”

—TOMSTROUD,foundingmemberandformerpresidentofTheMasonryHeaterAssociation

“Awonderfulbook!Wellthoughtout,wellgroundedinnature,anddelightfulto

read.WhenIvisitedahousebuiltaroundamasonryheater,itwasa“justright”experience,andoneIhaveneverforgotten.Thisbookisagreatintroductionfromamanwhoobviouslyknowsandlovesthesubject.”

—DEBRALYNNDADD,authorofHomeSafeHome

“WhenItravelinthenorthernstatesoftheU.S.—particularlyNewEngland,wheremostpeopledependonheatingwithoil—Ifearforthosemillionsoffolksforwhomdepleting,climate-changingfossilfuelsareallthatstandbetweenwintercomfort,ontheonehand,anddeathbyfreezing,ontheother.MasonryHeatersexploresoneofthemostpromisingalternatives,anditsmessageneedstogetoutfarandwide,andfast.”

—RICHARDHEINBERG,SeniorFellow,PostCarbonInstitute,andauthor

ofTheParty’sOver:Oil,WarandtheFateofIndustrialSocieties

“Masonryheatersprovideaquietcomfortthatmustbeexperiencedtobebelieved.Inthisbook,KenMateszshareshisloveofmasonryheatersandartfullyexplainshowtheywork,howtousethemtoprovideefficientandcomfortableheatthroughouttheday,andwhatittakestoinstalloneinyourhome.Thisisatrulydelightfulbook.”

—DAVIDBAINBRIDGE,coauthorofTheStrawBaleHouseandcoauthorofPassiveSolarArchitecture

“MasonryHeatersisinformationalacrosstheboard,andsharescommon,advantageouscharacteristicswithpassivesolardesign.Bothmethodsofheatingrelyonheattransferbyradiationratherthanconvection,whichgivesamorenaturalfeelingwhilereducingdraftsandnoise;bothutilizethermalmass,whichgivesgreaterthermalstability;andbothcanallowindependencefromenergyshocksandpricefluctuations.Ihighlyrecommendthisbookforpeople—inanyfield—whoareinterestedinlearningaboutthedesign,construction,anduseofthissuperiorsystemofheating.”

—KENHAGGARD,coauthorofPassiveSolarArchitecture

MASONRYHEATERS

PhotocourtesyofTulikiviCorporation.

MASONRYHEATERS

Designing,Building,andLivingwithaPieceoftheSun

KENMATESZ

CHELSEAGREENPUBLISHINGWHITERIVERJUNCTION,VERMONT

Copyright©2010byKenMateszUnlessotherwisestated,allphotographsandillustrationscopyright©2010byKenMateszAllrightsreserved.Nopartofthisbookmaybetransmittedorreproducedinanyformbyanymeanswithoutpermissioninwritingfromthepublisher.

ProjectManager:PatriciaStoneDevelopmentalEditor:CannonLabrieCopyEditor:LauraJorstadProofreader:EricRaetzDesigner:PeterHolm,SterlingHillProductions

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OurCommitmenttoGreenPublishingChelseaGreenseespublishingasatoolforculturalchangeandecologicalstewardship.Westrivetoalignourbookmanufacturingpracticeswithoureditorialmissionandtoreducetheimpactofourbusinessenterpriseintheenvironment.Weprintourbooksandcatalogsonchlorine-freerecycledpaper,usingvegetable-basedinkswheneverpossible.Thisbookmaycostslightlymorebecauseweuserecycledpaper,andwehopeyou’llagreethatit’sworthit.ChelseaGreenisamemberoftheGreenPressInitiative(www.greenpressinitiative.org),anonprofitcoalitionofpublishers,manufacturers,andauthorsworkingtoprotecttheworld’sendangeredforestsandconservenaturalresources.

LibraryofCongressCataloging-in-PublicationDataMatesz,Ken,1964-Masonryheaters:designing,building,andlivingwithapieceofthesun/KenMatesz.p.cm.Includesbibliographicalreferences.eBookISBN:978-1-60358-311-41.Stoves,Masonry.2.Dwellings--Heatingandventilation.I.Title.

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2010019837

ChelseaGreenPublishingCompanyPostOfficeBox428WhiteRiverJunction,VT05001(802)295-6300

www.chelseagreen.com

TOMYPARENTS,JOHNANDRUTH,WHOTAUGHTMETHEVALUEOFWORKDONEWELL.

CONTENTSForewordIntroduction:WhatIsaMasonryHeater?

PARTONERedefiningtheHearth

1.TheHearthIstheReasonfortheHouse2.ABriefHistoryofFireandHotRocksinNorthAmerica3.ThermalComfort:TheVerticalRadiantAdvantage4.BenefitsofMasonryHeaters

PARTTWODesigningaPieceoftheSun

5.Location6.DesignOptions7.HeatingRequirementsoftheHouse

PARTTHREEBuildingaPieceoftheSun

8.TheInnerLife—CoresandFlues9.Codes,Clearances,Footers,andFoundations

PARTFOURLivingwithaPieceoftheSun

10.FueltoBurn11.UsingaMasonryHeater,Bakeoven,andCookstove12.MasonryHeaterMaintenance

AppendicesA.ResourcesB.R-ValuesofCommonBuildingMaterialsC.ElevationandOutsideDesignTemperaturesforVariousCities

D.HeatingDegreeDaysofVariousCitiesEndnotesBibliographyAcknowledgmentsAbouttheAuthor

Thismasonryheaterhasanoven(theupper,archeddoor).Theheaterisfinishedinfinelydetailedstucco.Thecustomerwantedarelativelyconventionalfireplacelookblendedwithafive-sidedcorner-heaterdesign.Threesidesarevisibleherewhilethetwobacksidesfitsquarelyinthecorner.

FOREWORD

Mybrother,Howie,andIbecameBoyScoutsinthelatel950’s.Asidefrommasteringeveryimaginableknotonourside-by-sidesteelbedposts,scoutingforuswasallaboutcamping,andcentraltothecampingexperiencewasFire.Welearnedhowtofinddrywoodandtinderinallweatherconditionsandhowtobuildsafecampfires.Earlyinourscoutingjourney,weenteredafire-startingcompetitionusingflintandsteel.Westudiedtheliterature,foundourflintandsteel,andcookedoldshredsofcottonsheetsinametalBand-Aidcaninourmom’sovenuntilthecottonwasbone-dryandblack.Whenthefire-startingcompetitionwasheldindoorsatthewooden-balconiedjuniorhighschoolgym,oneofusstruckthesteelagainsttheflint.Theothercaughtthelivesparkinanestofblackcloth,carefullyfoldedtheclothoverthesparkandswungtheclothincircleshighandlowlikeawindmilluntil,inonlyseconds,wehadfireinourhandsandwonthecontest.Wedidnotrealizeatthetimethatwehadalsocaughtthefireinourhearts.Yearslater,Iwaspushedbyaninvisiblehandandurgedbyasilentbutvery

clearvoicetotakeonthemissionofbringinganenduringmasonryheatertraditiontoNorthAmerica.Creatingthesparkofinterestinmasonryheaters,teachingothershowtobuildthem,fanningtheknowledgeofmasonryheaters,andbringingthemintotheirproperplaceastheHeartoftheHome—thishasbeenmylife’swork.Manypeopleknowintuitivelywhentheyseeandexperienceamasonryheaterforthefirsttimefunctioninginahomethatthereissomethingtrulyunique,evenextraordinary,aboutthesehuge,gentle,warmingsouls.Overacareerofmorethanthirty-fiveyearsbuildingandstudyingmasonryheaters,bakeovens,andcookstoves,someofthelogic,physics,andgoodnessofmasonryheatershavebeengiftedtomeandtootherswhobuildthem.Duringthatsameperiodoftime,Ihavebeengraduallyinvitedtoexploreevendeepermysteriesoffireanditshealingpower.Recently,Ibegantostudy,inmoreearnest,someoftheancientfire-giftingstoriesindigenoustoEuropeandtheworld.Intheclassicchildren’staleofCinderella,thelostglassslipper,leftonthe

stepsatthestrokeofmidnightatthegreatball,iscarriedbythePrincethroughouttheland,whilehelooksforthebeautifulmaidenwhoworeittohis

ball.Theslipperonlyfitsonefoot,theperfectdustyfootofthemaidofthehearth,Cinderella.Wealllovethemagicofthestory,thejusticeandtheunionofthetwopartners,andeventheforgivenessofthestepmotherandherdaughters.Itisthetimelessstoryofthereturntorightrelationshipandharmonyinmattersoftheheart,whichiswherethefirelivesandserves.Manyyearsago,Ireadthattherewasanancientfire-carryingtraditionin

Mainethatinvolvedlargeclamshellslinedwithbluemarineclayandaspiralofsomekindoftinderfunguswoundlikeafusethatcouldbecarriedasalivingsparkallday.Thiswinter,readingawonderfulbookbyKerryHardycalledNotesonaLostFlute:aFieldGuidetotheWabanaki,Ilearnedthattheshellscouldbecarriedinawoodchuckpeltslippedoverabeltthongorsashwiththewoodchuck’sowncleanedskullthecounterbalanceweighttotheclay-linedshellswiththeirtinderfungusfuse.Agiftedwoodsmanandteacherfriend,RayReitze,saidthatheknewthetraditionwellandthattheWabanakihadusedthongedconchshellssimilarlylinedwiththeclayandtinderfungusfuseandcarriedtheshellsinapackbasketintheirday-longcanoetrips.RaysaidthatthetinderfunguswastheblackChagafungusthatgrowsonthebirchtree.Healsopointedoutthatwhilethetinderfunguscouldholdthefire,hisMicmacnativeelder“grandfather”hadtaughthimthatthespindleforthebowdrilltomakefireshouldbemadeofspruce,whichwasthewoodchosentocarrythefirewithinitself.WhileinNewZealand,teachingamasonryheaterworkshopthiswinter,I

learnedthattheMaoriculturehadastoryaboutthegrandmotherfirevolcanohidingthefireinthreetreesduringthestruggletocreaterightrelationshipbetweenhumansandfireandwater.Allthreeofthesetreesarethechosenandknowntreesformakingfirewithfrictionbythenativepeople.AmongtheancientHuicholpeople(whocallthemselvesWixáritira)of

Mexico,thereflourishesandissharedaremarkabletraditionofmeetingGrandfatherFire(Tatawarì)himselfinawaythattheheartisopenedandthefearsandthemindareputatease,wherecommunitygrows,andthesacredrelationshiptoallthatis,isrememberedandrestoredandkeptalive.InKenMatesz’srichandwonderfulnewbook,MasonryHeaters,Kensweeps

awaytheashesofourignoranceaboutrightrelationshiptofire.Kenguidesusandexplainswithcrystal-clearandgentleclarityhowmasonryheatersarethemostintelligent,mostefficient,mostenvironmentallysoundandsustainable,mostbeautiful,andmosthealthfulformofheatingthathumanshaveever

known.ThereismoreknowledgeaboutmasonryheatersbetweenthesetwocoversthanhaseverbeenpublishedbeforeinEnglish.In2010,asoilgushesupfromtheoceanflooroffthecoastofLouisianaand

asourearthwarmsaswecontinuetousepreciousresourcesisiftherewerenotomorrow,thisbookmakesitclearthatwewillonlyhaveachanceatenjoyingtomorrowifwelearnhowtoembraceandholddearinourliveswhatreallymatters.Masonryheaters,whichholdafire,alittlepieceofthesun,withhonorandcare,reallymatter.Theyshowusagentle,sustainable,intelligentwaytoliveinandheatourhomes.Catchthesparkofmasonryheatersinyourmindsandheartsandhandsasyou

readthisbookandfindwaystoblowthatsparkgentlyintolife.Dream,plan,andcarefullybuildandsharethiswarmthwithothers.

ALBIEBARDENJuly6,2010

INTRODUCTION

WhatIsaMasonryHeater?

“Whatisamasonryheater?”IfIhadadollarforeverytimeIhavebeenaskedthatquestion,Iwouldnotneedtobuildmasonryheatersforalivinganymore;Icoulddoitjustforthechallenge.Ihavefoundthat,overtime,mypersonalanswerhaschanged,muchasyouwouldchangeyourdescriptionofafriendthemoreintimatetherelationshipbecomes.Earlyinmyunderstanding,amasonryheaterwas“ahigh-efficiencyfireplaceofEuropeanoriginthatstorestheheatfromahot,fastfireinthousandsofpoundsofsolidmasonryforslowreleaseasradiantheatoverthenexttwelvetotwenty-fourhours.”Thereisnothingblatantlyfalseorwrongaboutthisdefinition,ofcourse,andIstillusethisinformationinanylongerconversationIhaveaboutmasonryheaters.Now,however,Idefineamasonryheateras“apieceofthesun—thewarmcenterofthehome’suniverse.”Youwillhearmasonryheaterscalledmasonrystoves,heat-storagefireplaces,

kachelofens,kakelugns,kemence,grubkas,grundofens,putz-grundofens,Russianfireplaces,Finnishfireplaces,Swedishstoves,contraflowfireplaces,radiantfireplaces,mass-storagefire–places,andmore.They’reallmasonryheaters,andtheyallworkonthesameprinciples.Theyallcreateaplacetogotofeelwarm,tobaskinthesun.Forwhateverreason,ittookmeyearsofbuildingmasonryheaterstorealize

thatthetypicalhometodayhasnoinvitingplaceofluxuriouswarmth.Thethermometerinahomemightread70°F,butpeopleinthathomestillmayhavecoldhandsorfeet,ormaysimplyfeelcold.What’sworse,thereisnoplaceinthathouseforapersontogotofinallyfeelwarm.Withapieceofthesun—amasonryheater—inthemiddleofahome,thereisnoneedtofeelcoldbecausethereisaplacetogo.There’salwaysaplacetosoakupthesun.WhenIwasateenager,mydadexperimentedwithsolarwaterheating.I

becameinterestedinsolarheatingaswellandthoughtthatpassivesolarheatingwasthewaytogowhenitcametoheatinghouses.Nooneownsthesunortheenergyitsendsourwayeveryday.It’sfreeenergy.It’snaturalenergy.Passivesolarheatingisgreat,butitstillhasadrawback:There’snoaccountingforlong

weekswithoutblueskiesinalongwinter.That’swhatmakesmasonryheatersevenbetter.Masonryheatersarepassivesolarenergyunderhumancontrol.Withthissimpletechnology,yougettodecidewhenthesunshinesinyourhouse.Andwhodoesn’twantthathappeningeverydayandalldaylong?Itisfascinatingtowatchtheevolutionofideasconcerningenergy

conservationandgreen,sustainableenergy.Youhavetowonderatthecomplicatedstrategiespeoplewillundertaketo“solve”thedilemmaofbecomingenergyself-sufficientasasociety.Somanypeoplehavebecomeaccustomedtocentralizedsourcesofpower,suchasthegascompany,electriccompany,orofcourseoilcompany,thattheybelievethewaytofreedomfromforeignoilandenergyistocreatemassiveinfrastructureforagreenreplacementforfossilfuels.It’sasifwe’vediscoveredthatbeingdependentonforeignnationsforenergyisanot-so-goodidea,butmakingsurethatpeoplearedependentoncorporationsforenergyisagreatone.Thuswehavemassivestudiesandcorporatedevelopmentofwaystoturn

foodcropsintoenergycrops.Andevenmoretothepointistheenvironmentalbuzzwordforrenewablesolidfuels:biomass.Biomass,ofcourse,istheeducatedperson’stermforwhatcommonpeoplehaveusedforfuelsincetimeimmemorial—wood,plants,andanimalwastes.Wholeindustriesarepoppingup“creating”thenextfuelonwhichpeoplecanbecomedependent.It’snottechnologicallyadvancedjusttoburnwoodcutfromthetreesintheback40;instead,wemusthavesomelargecompanyfirstturnthewoodintowoodpelletsbeforeweburnthatwoodinstoves.

FIGURE1.Whowouldn’twantthesunshiningintheirhomeeveryday?Thisbrick,stucco,andsoapstoneheatergentlyseparatesalivingroomfromadiningroom.Thebrickchimneyisintherightforeground;thesoapstone-toppedbenchescontainfluesthatmakethesewarmseats.Thestuccomassbehindthechimneycontainsmorefluesforheatstorage.PhotocourtesyofNewEnglandHearthandSoapstone.

Ironically,just150yearsagotheaverageNorthAmericancitizenwasenergyself-sufficient.Atthattime,afamilyknewithadtosupplyitswinter’sfuel,whichwasprimarilywood(thoughcoalwasbecomingmorecommon).Thiswasn’tsomethingpeoplethoughtmuchabout.Theyjustdidit.Iftheydidn’tsecuretheirwinter’sfuel,theywouldbecold.Itwasassimpleasthat.Todayweactlikebeingenergyself-sufficientisapipedream.Certainlypoliticiansandlargecorporationswouldlovefortheaveragepersontobelievethatbeingenergyself-sufficientisnearlyimpossible.Otherwise,whatwouldweneedthemfor?Advancesindesignandfunctionnowallowthecreationofstate-of-the-art

wood-firedmasonryheatersthatapproachtheenergyefficiencyofmoderngasfurnacesandboilers.In1850,homeinsulationwasnonexistent,andpeopleheatedtheirhomesusingopenfireplacesorverybasicmetalstoves.Imaginethequantitiesoffuelrequiredinanattempttoheatanuninsulatedhomewitha20or

30percentefficientstoveorfireplace!Now,withtoday’sbestmasonryheatersathighefficiencyandhomeswellinsulated,heatingwithwoodcouldbeabreeze,exceptforonething.

FIGURE2.Heatingwithamasonryheatercanbegreen,sustainable,enjoyable,andhealth-supporting.Thistall,narrowsoapstonemasonryheatertakesuplittlefloorspace,buthasenoughsurfaceareatoproduceaconsiderableamountofheat.PhotocourtesyofTulikiviCorporation.

Themissingpieceofthepuzzleishomesize.TheaveragehomesizeintheUnitedStatesinthe1950s,forexample,waslessthan1,000squarefeet.Nowitismorelike2,500squarefeet.Ipersonallygrewupquitecomfortablyinan1,100-square-foothomewithafamilyoffour.Mywifegrewupinahousesmallerthanthatwithafamilyofnine.Iamnotsuggestingthateveryonemusthavea1,000-square-foothome.Iam

pointingout,however,thatmostaveragefamiliescouldbequitecomfortableinhomesof1,500squarefeetanditwouldbeeasytobeenergyself-sufficientwithalittlepassivesolardesignandahigh-qualitymasonryheater.Withgoodinsuation;modern,high-qualitywindows;andamodest-sizedhome,afamilycantodaybeenergyself-sufficient(forheatingpurposes)withlittleexertion.It’sentirelyconceivablethatsuchahomecouldbeheatedwithlessthantwocords

ofwoodannuallyata2009(inOhio)costoflessthan$400(orforfreewithsomeextraeffort).Itallcomesdowntopersonalpriorities,ofcourse.Ifsomeonedoesn’tmind

beingdependentonsomedistantlandorcorporation;ifsomeonedoesn’tmindbeingsubjectedtotheupsanddownsofenergymarkets;ifsomeonedoesn’tmindthepoliticsandmilitaryconflictsthatarisearoundenergy;ifsomeonedoesn’tmindhavingaheatingsystemthatisuselessifawinterstormcutspower;ifsomeonedoesn’tmindhavingcoldfeetandnowhereinthehousetogetwarm;ifsomeonecanignorethemanybenefitsofmasonryheaters,thenamodesthomeandmasonryheaterareoflittlevalue.Butforsomeonewhoreallycravesbeingfreefromdependenceandlikestheideaofgettingenergyfreefromtheearthandsun,thismayallsoundveryenticing.Thisisnottosayit’simpossibletohavealargerhouseandheatitwitha

masonryheater.Itjustmeansthequantityoffuelthat’sneededincreases.Themorefuelneeded,themoreworkisrequiredandthelessattractivethewoodheatingoptionbecomes.Theharderitistobeenergyself-sufficient,thefewerpeoplewilldoit.Inthisway,planningandbuildingaverylargehouseislikeaskingforanexcusetobedependentonothersforfuel.It’saself-defeatingbehavior,likebuyingafullcartonofcigarettesandallthewhilesayingit’stimetoquitsmoking.Largehouses,likegasoline-poweredautomobiles,aredesignedforusingfossilfuelenergy.AsIsaid,it’sallaboutpriorities.Thisbookisaboutreturningtoourrootsandunderstandingwhydoingsois

notabadideawhenwecanapplysomerefinedknowledgetotheproblem.Woodheatingcanbe“green.”Itis“sustainable.”Itcanalsobesimpleandenjoyable,evenhealth-supporting,withamasonryheater.PeopletodayinNorthAmericacanbeenergy-independentwiththesimpletechnologiesthathaveexistedforcenturies,buthavebeenrefinedbymodernresearchanddevelopment.It’snotnearlyashardaspoliticiansandcorporationsmakeitsound;itmerelyrequiresresettingprioritiesandacquiringalittlebitofknowledge.

FIGURE3.TheinnerworkingsofasquatAustrianheater.FromDavidLyle,TheBookofMasonryStoves,p.119.

Ifindthatpeoplearealreadyreturningtotheirrootsbutdon’tquiterealizeit.Newhomestodayboastgraniteorsoapstonecountersandwoodfloorsandtrim.Peoplearerememberingthatthesematerialsarereal.Theyarethestandardthatmanufacturedproductscanneverquiteduplicate.Realstoneandrealwoodhavemadeacomeback.Noteveryonehasyetgottenbackto“real”whenitcomestofire,however.Ifrequentlygetcallsfrompeoplesaying,“Well,webuiltthehousewithagasfireplace,butithardlygivesoffanyheat,andit’sboring.”Whatthey’retryingtosayisitisn’treal.It’sagasfirepretendingtodowhatwooddoesforthesoul,theeyes,theheart,andtheskin.Realfireandrealheatwillalsomakeacomeback,Ipredict.Masonryheatersareheretostay.Thereisnobetterwaytoburnwood.There

isnoeasierwaytoheatwithwood.Thereisnomorecomfortableheatthanwhatcomesfromamasonryheater—apieceofthesun.Whatisamasonryheater?It’sasolutiontorestoringhealth,well-being,self-sufficiency,sustainability,andreality.It’sagrassrootssolutiontoourenergydilemma.ItwasMahatmaGandhiwhosaid,“Bethechangeyouwanttoseeintheworld.”Ifyouwanttoseeenergyself-sufficiencyinNorthAmerica,startbyharnessingthesunviaamasonryheaterinyourhome.

FIGURE4.AGermanorAustriandesignthatismoreupright.FromDavidLyle,TheBookofMasonryStoves,p.178.

So,youmightstillbeasking,justwhatisamasonryheater?Amasonryheater,ofcourse,canbedefinedinmuchmoretechnicaltermsthanjust“apieceofthesun.”Infact,industry-wideconsensus,asdevelopedthroughASTMInternational,callsamasonryheater

aventedheatingsystemofpredominantlymasonryconstructionhavingamassofatleast800kg(1760lbs),excludingthechimnneyandmasonryheaterbase.Inparticular,amasonryheaterisdesignedspecificallytocaptureandstoreasubstantialportionoftheheatenergyfromasolidfuelfireinthemassofthemasonryheaterthroughinternalheatexchangefluechannels,enableachargeofsolidfuelmixedwithanadequateamountofairtoburnrapidlyandmorecompletelyathightemperaturesinordertoreduceemissionofunburnedhydrocarbons,andbeconstructedofsufficientmassandsurfaceareasuchthatundernormaloperatingconditions,theexternalsurfacetemperatureofthemasonryheater(exceptintheregionimmediatelysurroundingthefuelloadingdoor(s)),doesnotexceed110°C(230°F).1

FIGURE5.ARussiandrawingofsomeofthemanydifferentwaysthatthefluescanbeconfiguredinamasonryheater.FromDavidLyle,TheBookofMasonryStoves,p.97.

Inshort(andpracticallyspeaking,forNorthAmerica),amasonryheaterisawood-burningheat-storagefireplace.Unlikeconventionalopenfireplaces,however,suchaheatersavesthebulkoftheheatproducedbythewoodfireandstoresitinmassforlong-termreleaseratherthanlettingtheheat(androomair)goupthechimney.AsASTMInternational’stechnicaldefinitionhasit,theheatissavedandstoredbyvirtueofheatexchangetakingplaceinvariousfluechannels.Thesefluesarelargelyresponsiblefortheshapeofthemasonryheater.

FIGURE6.Amasonryheaterisn’talwaysjustabig,rectangularbox.Inthisphoto,it’sachallengetoknowwheretheheaterbeginsandends.Curvedfaces,tilemixedwithstucco,andwoodensittingareasmakethisheateraone-of-a-kind.PhotocourtesyofBiofire,Inc.

Overthemillennia,masonryheatershavetakenmanydifferentformsinthecoldregionsofEuropeandAsia.Whileafireplaceisafireplaceisafireplace,thatis,afireboxthatventsupachimneyabovethefirebox—thus,aRumfordfireplaceandawalk-infireplacearestilljustfireplaces—aSwedishmasonryheatermaybevastlydifferentinappearanceandconstructionthananAustrianone;thedesignandshapeofapeasant’smasonryheaterinHungarywillbedifferentfromtheprince’sheaterinRussia,andsoon.

Inthiswayitisimpossibletopointtoonemasonryheaterandsaythatitisthearchetypalmasonryheater.OnemasonryheaterinAustriamayhavefluesliketheonesseeninfigure3—makingaheaterthatissquatandlow.Someoneinthatregion,seeingthedesignofamasonryheaterforthefirsttime,mayafterwardsay,“Ohyeah,nowIknowwhatamasonryheaterlookslikeinside.”ThenthatpersonmaytravelintoGermanyandseeonewithflueslikeinfigure4.Nowitstartsgettingconfusing:“Youmeanamasonryheaterisn’tjustoneofthosesquatthingsIsawinAustria,butitcanbetalllikethistoo?”Ofcourse,yesistheanswer.IlikethedrawingoffluepatternsfromRussiashowninfigure5becauseit

startstochartthepossibilities.Somedesignshavethefluegasesgostraightupfirst,andthengobackdown.Somehavetheexhaustgounderthefireboxbeforegoingup.Somehavethefinalexitfromtheheateruphigh;others,downlow.Yetevenwithadozenorsooptionsshownononepage,onlythesurfacehasbeenscratchedintermsoftheopportunitiesavailable.Thisbookisinspiredbytheremaininginfinitepossibilities.So,ifyouhaveseenamasonryheaterinCanadaortheUnitedStatesbefore,

anditlookedlikeabigbox(or,asafriendofmineputit,likearefrigerator),carefullyturnpagebypagethroughthistextasweinvestigatealittlefurther.Youmightdiscoverthat,althoughyoumaynothaveroominyourhouse,yourhouseplans,oryourroomadditionforabigbox,youdohavetheneedforamasonryheater.

PhotocourtesyofWarmstoneFireplacesandDesignswithDaleHisler.

I

PARTONE

RedefiningtheHearth

nourmodernera,thehearthhasslippedawayfromthecentralroleitplayedinthelivesoffamiliessincehumansfirstlearnedtocontrolfirethousandsof

yearsago.Alotofpeopleneverevenseearealfireonaregularbasis.Outofsightandoutofminditmaybe,butitisnotoutofvogue.Infact,inmanyways,fireismoreimportanttolifetodaythaniteverhasbeen.Modernlifewouldcometoastandstillinstantlywithoutfire.Somethingthiscentraltoourexistenceissomethingyoucouldcalloneofthe

fundamentalsoflife.Ifitisafundamental—abasicnecessity—thenitmustbeprettyspecial.Ifitiselementaltolife,thenmaybeitactuallybelongsinthemiddleoflife,inthemiddleofahome.Therearesomeprettyprofoundreasonswhyafunctionalhearthreallydoesbelonginthemiddleofthehome,andthatistheprimaryfocusofthisfirstpartofthebook.Chapter1focusesonthefundamentalnatureoffireandenergy.Masonry

heatersarebroadlyintroducedasarenewwaysoflookingatcomfortandefficiency.Fireistheultimatetool,andmasonryheatersareexpertatusingit.Thedesireforheirloomqualityinahome—timelessnessinbothfunctionandappearance—mesheswellwithwhatmasonryheatershavetoofferinregardtothefundamentalsdescribed.Chapter2takesaturntowardhistory.Remarkably,thoughmasonryheaters

havenotyetbecomemainstreaminNorthAmerica,peopleintheUnitedStatesandCanadaaresubtlyandregularlyexposedtotheconcept—thoughmanyneverrealizeituntiljusttherightmoment.AlsoincludedisaconcisesummaryofhowmasonryheaterawarenesshasgrownintheUnitedStatesandCanadaoverthelastthirtyyears.Chapters3and4lookatafullrangeofbenefitsderivedfromamasonry

heater,manyofwhichcannotbeduplicatedbyheatingahomeinanyotherway.Masonryheatersareasourceofradiantheat,andthathasameaningfewpeoplereallyunderstand.Thoughthesunisaradiantheaterfortheearth,peopleseemtohavelosttheabilitytodiscriminatebetweenradiantheatandothercommon

heatingmethods.

FIGURE1.1.Amasonryheaterisapieceoffunctionalart.Herestoneandstuccoarecombinedonthefacade,andthereisaheatedsittingarea.Noticehowtheleftsideofthetallelementissculptedtoartfullymissthestructuralceilingbeam.Thelittleblacksquaresareashcleanoutdoorsandgiveaclueastowhereexhaustandheattravelinamasonryheater.DesignedandbuiltbyStovemaster;photocourtesyofAlexChernov.

CHAPTERONE

TheHearthIstheReasonfortheHouse

HomeIsWheretheHeart(h)Is

Brrriiinggg!Astunningringfromtheelectricalarmclockendsanightofblissfulsleep.Amanhobbleshalfdazedintothebathroom,switchingonthelight,turningonthehotwatertotakeashower,shave,combhishair.Theday’sonlybegunandalreadyhehasusedonecontraptionafteranother.Tools.Heeatshisbreakfast;forks,knives,spoons,mugs,anddisheshelpaccomplishthemealconsumption.Moretools.Humanshavespentthousandsofyearsdevelopingtoolsfromthesimpletothe

complex.Theknife,atoolusedfourthousandyearsago,getsdailyuseinthehometodaycuttingthemorningpastry,whilee-mailsaredownloadedonthePC,atooluniquetothetwentKiethandtwenty-firstcenturies.Peoplehavedistancedthemselvesbylight-yearsfromallotheranimalsbytheirtools.Itistruethatotheranimalsusetools.Butonlyhumankindusestoolstomakeothertools,andthosetoolstomakeyetmoretools.Arguablythesinglemostsignificanttoolhumanityhasmakesalltheothers

possible:YoucouldnotuseabutterknifeoraPCtodaywithouttheblessingsofthegodsoffire.Fromfirecomesmoltenmetalandturningturbines.Withfirethereistravelfromthegaragetotheoffice,littleexplosionsturningthewheelsofcars,thewheelsthemselvesdisksofoncemoltenrubberandsteel.Onewayoranother,indirectlyornot,today’shomesareallheatedwithfire.Fireistheultimatetool.Forearlyindigenouscultures,lifeitselfunfoldedaroundthefirebecausethat

iswherefoodwaspreparedandfromwherelightandwarmthemanated.Thereissignificancetotheverytermaroundthefire.Foritpresumesthatthefireisinthecenter,orheartoftheactivity.Duringtheday,themembersofthetribemayhavescattered.Somewouldgohuntingorcollectingfood;otherswereherdinganimalsorcollecting,yes,firewood.Butasthedaylightwanedandeveningchillsetin,lifecontinuedaroundthebeatingheartofthefire.Aslongasthefire

burnedbrightly,lifecontinuedandculturegrew.Itisaroundthefirethatcraftscontinued,storiesweretold,discussionswereheld,decisionsweremade,dancerstwirled,childrenplayed,andfoodwaseaten.Earlyon,someonerealizedthateverytimeitrained,thefamilyortribalfire

wasextinguished.Sofiresthenwerebuiltunderanoverhangingrockorinsideacave.Eventually,itmadesensetobuildastructurearoundthefirethatwouldnotonlyhouseit,butshelterthepeople,too.Thusbegantheprocessofbuildinghomes,fromtheneedtoprotectthefirethatcookedthefood,warmedthebodies,andfueledtheimagination.Ourancestorsknewinstinctivelythatthisamazingforceintheirliveswascentralandthatifitwasprotected,cherished,andnurtured,itwouldalwaysbeaforceforamorefulfillinglife.Thehearthwasborn.Today’smodernlife,whenyouthinkofit,stillhappens“around”afireinthe

sensethatnothingwedocouldhappenthewayitdoeswithoutfire.Andyetyoucouldwalkuptoadozendifferentfolkstodayandaskthemwhentheylastsatandenjoyedasimplewoodfireandbesurprisedtofindthatithasn’thappenedinmonths,maybeyears.Ifyoutookthesesamepeoplehostageonedayandplacedtheminfrontofafireforoneevening,theywouldbemesmerized.Thereissomethingessentialorprimalaboutablazingfire.Untilthetwentiethcentury,humansalwayshadarealwoodfireintheirlives

—“always”beingmostofthelastfifteenthousandyears.Perhapshavingablazising,cracklingflamewithinourviewprovidessomeessentialnutrient,justasweneedthesunonourskintomanufacturevitaminD.Thiscertainlywouldhelpexplainwhyafireissuchamagnetforalmostanyone.InAPatternLanguage,ChristopherAlexanderwrites,“Theneedforfireisalmostasfundamentalastheneedforwater.Fireisanemotionaltouchstone,comparabletotrees,otherpeople,ahouse,thesky.”1

FIGURE1.2.Withamasonryheatercomplexlikethis,muchoflifecanstillhappenaroundthefire.Thissoapstonecreationfeaturestwowood-firedovensandacooktop,soafamilycandoallitscookingandheatingfromthisonecentral,integratedmass.Noticehowthemainfireboxfacesonearea,yetthecooktopisfirmlypartofthekitchen.PhotocourtesyofTulikiviCorporation.

Theneedforfire,then,isnotsomuchbodilyasspiritualinnature.Itservesthehomewithitsutilitarianheatingandcookingwhileactingasaspringboardfortheimaginationandtheemotions,too.Justasachildliesonthegroundwatchingthecloudschangeshapes,watchingafireentrancesusandstimulatesourthoughtsanddreams.Itisanenergythatgroundsusandmakesusfeelsafe.Webster’sdefineshearthas“thefloorofafireplace.”Thisbook,however,

willberedefiningthehearthastheheartandsoulofahouse.Anyonecanbuildaboxwitharoofonit,protectedfromtheelements.Untilthatstructurehousesafireofsomekind,itisnotaplaceinwhichanyonereallywantstolivepermanently.Peopleneedtobeabletoeatdeliciousfoods;weneedtofeelwarmthwhentheweatheroutsideturnsbitter;and—perhapsmoreimportantlythanyoumightthink—weneedahearththatencouragesustoponder,to

imagine,andtodream.Thetelevisioncan’tdothis,norcanvideogames.Evenhumaninteractionandconversationdon’tprovidethatsameimpetustothinkasisstimulatedwhenasingleindividualwatchesfirewoodburn.Itisfairtoask,“Iftherearesuchemotionaltiestofireanditissosignificant

tolife,whydon’tmorepeoplehaveafiretovieweveryday?”Therearemanypossibleanswerstothis.Fewcoulddisagree,however,thatsomeoftheanswerliesinperceptionsofcomfortandthemodernromancewithtechnology.Comfortisanothertermwemustevaluateinordertoplacethehearthinperspective.

RedefiningComfortAmericanshavearomancewithtimeandtemperature.TheywearwatchesontheirwristsandbrowsetheWeatherChannelfortheday’shighsandlows.Sure,it’snotjustthetemperatureinwhichtheyareinterested.Theyalsowanttotracktheweatheritself.Temperature,however,isthebaseline.Ifatleastthetemperatureforecastisknown,weknowhowtodressaswemakeourwaythroughtheday.Ifit’s20°F,theparkaandmittensareinorder;90°andoutcometheswimtrunks.Thentherearethoseunpredictablespringdaysthatmightbringatotalreversalintemperatures.Butifit’s65°andsunny,coatsareleftontheirhangers.Fortunately,technologicallyadvancedheatingsystemscontroltheindoor

environmentalmosttotally.Youcanbesurethatwhenyouwakeinthemorning,it’s70°F.It’snotjustthattemperatureinthebedroom.It’salso70°inthekitchen;70°inthediningroom,livingroom,bathroom,andfamilyroom.Theenvironmenthasbeensetonautomatic,perpetuallypilotingeveryoneintoaparticularclimatethatisalwaysmoderatelywarm.Sensitiveelectronicthermostatsconstantlymonitortheindoortemperature.A

changeof2°Ftriggerstheheatingsystem.Programmablethermostatssaveenergybyallowinglowertemperatureswhileyou’reasleeporaway,butguaranteeingthehouseiswarmerbythetimeyou’rehomeorawake.Thereareevenelectroniccontrolsforhumidity.Nowhardlyafingerisliftedtobe“comfortable.”

FIGURE1.3.Stuccoandstonecombineinthislargeheater.Noticehowthechimneyisseparatedfromtheheateritselfbyawood-storagearea.Theheaterandchimneyaretiedtogetherabovethewood-storagealcovewithalongcurvedstone.Fire,stone,andwoodarebasicnaturalelementsandhaveastrongeffectonhumanbeings—sometimesatanunconsciouslevel.PhotocourtesyofTemp-CastEnviroheat.

Well,thereismoretolifethanthiskindofuniformthermalcomfort(whichisdiscussedingreaterdetailinchapters3and4).Peoplealsogaugecomfortbythelevelofeffortperunitoftime.Itseemsthatformanypeople,reducedeffortequalsgreatercomfort.Thisisthereasonformanyofthegadgetswehave.Time-andlabor-savingdevicesabound.Sucharetheresultsofboththeindustrial/technologicalageandtheinformationage.Itisamazingthattheaveragemodernindividualnowtravelsfartherfromhomeeachdayjusttogotoworkthanmanypeopleofacouplehundredyearsagotraveledinayear.Therearemachinestoopencans,machinestowashcars,andevenmachinesforbrushingteeth.Thelistgoesonandon.

Presumably,thetime-andlabor-savingdevicesfreemoretimeforpeopletoenjoyotheraspectsoftheirlives.Insteadofwashingthecarbyhand,thereismoretimetoplaywiththekids.Insteadofchoppingallthosevegetableswitha

knife,thefoodprocessordoesit,andthereismoretimetoenjoythemeal,ormakemorecourses,orgooutsideandplantsomeflowers.Likewisewiththemoderncentralheatingsystem:Sincethefurnacetakescareoftheheating,thereisnoneedtogather,split,andstackfirewood.There’spresumablymoretimetodootherthingsornothingatall.Therearesomefundamentalprinciplesinphysicsknownasthefirstand

secondlawsofthermodynamics.Manyhaveheardthefirstlawstatedsomethinglike,“Energyisneithercreatednordestroyed,onlyconvertedfromoneformtoanother.”However,itisoftenforgottenthatthesecondlawcontinuesbysayingthatwhenenergyisconvertedfromoneformtoanother,thenewformofenergyislessusable,orfunctional,oravailable.Anotherwayofexpressingthesecondlawisthatheatalwaystravelsfromthe

warmerareatothecolder.Forexample,whenapieceofpaperisburned,foramomentthereisalotofheat(energy).Afterthatbrieffire,thetemperaturespikequicklydisappearsandwhatisleftareafewashesandaroomthatfeelsnowarmer.Theblastofmomentaryheathasbeenswallowedbytheimmensepoolofcoolerairintheroom.Thepotentialenergythatwasinthepaperhasnotbeendestroyed,butitwouldbeimpossibletoextractthatequivalentenergyfromthoseashesandtheinfinitelysmallchangesmadetothemoleculesofairintheroomanduseitforanyfuturepurpose.Thesecondlawisalsoknownasthelawofentropy,orthemeasureofthe

totalamountofenergythatisnolongerreadilyavailabletoperformanytaskoncetheinitialtaskiscompleted.Itcanbesimplystatedthatthisisameasureofthequalityoftheremainingenergy.Entropyisalawthataffectsmanyaspectsoflife,including,specifically,energyexpendedinsimpledailyaffairs.FIGURE1.4.Masonryheatersworklikethesun,radiatingheatfromacentralsource.Hereisaverysimpleheaterincoloredstucco.Allitscorners,includingthoseonthelowershelfandthemantelsupports,haveroundedorbullnosededges.Thisdetailmatchestheroundedcornersthebuilderusedonallplasteredcornersinthehouse,suchasinthebeamoverhead.

Thatelectrictoothbrushisagoodexample.Ifyoubrushyourteethwithitdayafterdayforseveralyears,youmightsay,“Hey,lookatallthe(muscular)energyIsaved.Myteetharewhiteandcleanandit’snoeffortatallformetobrushmyteeth.”Youdirectlyexperiencethelackofeffort(manualenergy)usedtobrushyourteeth.Whatyoudon’tnoticeisanyofthefollowing:reducedhandandfingerdexterityandstrength,dependenceonagadgettodowhatotherwiserequiressomeskill,useofbatteries(storedenergy)thateventuallyrunoutofenergyandmustpopulatealandfill(orhazardouswastefacility).Thechosen

methodofbrushingteeth(withamachine)replacedaneffectiveone(properlybrushingyourteethwithanordinarytoothbrush)thathadgreaterentropy.Usingeffortswiselywillproducebetterqualityresults.Theentropyprinciple

stillisatwork,buttherateisgreatlyreduced.Manyunintendedandoftenunseenconsequencesofhigherentropyareeliminated.Entropyisalwaysworkinglikeanimpartialjuror:Ittakestheinformationitisgivenandgivesbackexactlywhatisdue.Thepeculiarthingaboutthisentropyideaisthatitispossibletoreduce,or

evenminimize,entropy.Inotherwords,youcanfindauseofenergysuchthatwhenthetaskisfinished,theenergythathasbeenconvertedhaslargelybeenturnedintoaformthatcontinuestobeavailableforuse.This“entropyreduction”is,infact,themainideabehindthepushtorecyclenewspapers,containers,cardboard,glass,aluminum,andsteel.Bytakingtonsofplasticbottles,say,andmeltingthemdownandmakingnewbottles,wemakeuseagainofasignificantportionoftheenergythatwasusedtomaketheoriginals.Theenergytomineordrillforrawmaterial,perhapssometransportation,andsomeprocessingstepshavealreadybeendoneonceandmaketherecycleditemsfullof“embodiedenergy”thatisusedtomakethenew.It’seasytoseethatifthosesameoldplasticbottleswerejustthrownintoalandfill,allthatembodiedenergyisjustwasted.Toreducetheentropy,theeffortputintoheatingahome,istogetamaximum

returnontheinvestmentinenergy.Whenitcomestoeffectiveandefficientheating,wecantakeourcuesfromnaturebecauseweliveinaworldheated,literally,byonecentralheatingunit:thesun.It’seasytoforgetthisfactonablusterydayinnorthernMinnesota,forexample,whentemperaturesdroptowellbelowzero.Attimeslikethatitappearsthatthesundoesamiserablejobofheating.Inreality,extremesofweatheraredirectlyduetothesheerpowerofthesun.Thesunisapurelyradiantheating“device.”Itdoesnotheattheairdirectly.

Checkingthelocalair-temperaturereadinggivesnorealclueastohowwellthesunperformsitsconstanttask.ThisbecomesobviouswhenwatchingaweatherreportshowingwidelyvaryingtemperaturesacrosstheUnitedStates,evenatsimilarlatitudes.Airtemperatureisonlyaffectedindirectlybythesun.Whatthesundoesissomethingmagicalthatisfullyexperiencedona

perfectlyclear,windlessday.From93millionmilesaway,youfeelamostpleasantwarmthonyourback,orface,orwhateverthesunshinesupon.Thisis

truewhethertheairtemperatureishotorcold.Thisisthesundoingitsthingatitsbest:radiatingheattowarmsome“thing.”A“thing”isanythingthathasanysignificantmass.Airisnotincludedinthisgroupofthings.Butoneitemthatisdefinitelyincludedisourplanet.Thesunspendsitsdays(andhumans’nights)sendinglow-levelinfraredradiantheattotheearth.Itisthisconstant,gentle,persistentheatwarmingthisearthandthethingson

it,sometimesatdifferentratesbecauseofclouds,smoke,smog,andfoliage,thatsetsthestagefortheweather.Acresandacresoffreshlyplowedrichgroundsoakupheatquickly,warmingtheairthatpassesoverit.Thatairrisesquickly,pullingmoreairbehindit.Warmairheremeetscoldairthere,andsoonthereisallkindsofweather.ItmightbewarmandbreezyinIowawhileitrainsheavilyinNewYork.Weatherofallkinds,whichresultsfromthemovementofwarmandcoldair,isproofpositivethatthesunisdoingitsjobofwarmingtheearth;thatthesunisstillshining.Weshouldtakenoteofwhatthesunisteaching.Itistheconstantwarmingof

theearthitself,nottheaironit,thatmakesthisplanethabitable.Thisisthesunusingthelowestrateofentropypossibletokeepusallalive.Life’sexistencedependsonthesunputtingoutenergytomakethingshappen.Allthejoysandunpredictabilityoftheseasonsareatestamenttothesun’senergy.Thosemodern,technologicallymarvelousforced-airheatingsystems,by

contrast,areafineexampleofmaximizingentropy.Airhasalmostnocapacitytostoreheat,andatthesametimeitislikeafluid.Likewater,itcan(anddoes)findthesmallestpossibleleaksinthehouseenvelope.Heatingairandtryingtoretainwarmairrequiresavastamountofenergy.Thatenergy,convertedtowarmairinahome,becomesvirtuallyinconvertibletoanyusableform.Theairiswarmedonce,slowlydisappearsthroughanyavailablecrackorcrevice,thenvanishesintothevastnessoftheearth’satmosphere.Itisinterestingthatpeoplehaveimitatedoneofthesun’seffects(warmair),ratherthanthesunitself,inordertosatisfyacravingforsteadystatewarmth—whichisonlyonedefinitionofcomfort.Forpurposesofthediscussionoffireand(morespecifically)masonryheaters,

itisimportanttoredefinecomfortwithinthecontextofenergyandentropy.Nolongershouldpeoplethinkofcomfortasasteady-stateconditionofunchangingtemperatureandaworldwherepeopleputforthlessandlesseffort.Really,thisisnotcomfortatall.Truecomfortisastateoffeelingwell,ofbeingwell.Webster’sdefinescomfortas“astateof,orthingthatprovides,easeandquiet

enjoyment.”Thisisnottobeconfusedwith“aneasylifeinwhichminimumeffortismade.”A“stateofeaseandquietenjoyment”issomethingthatisaccomplishedbydoingthingsfirst.It’snotpossibletoappreciateeaseunlesschallengeshavebeenmet.Itisunderstoodtodaythattruewell-beingisderivedfromalifethatbalanceseffortwithrelaxationorease.Inasense,realcomfortisthebackboneofthiswholebook.Anditallstarts

withthefire.Thefireisthereasonwecancomeinfromthecold.Almosteveryhousehasafireinitrightnow.(Atleastthisistrueforalmostanyhouseinaclimatezonethatexperiencesfourseasons.)Butusuallyit’salittleblueflameflickeringinsideametalboxhiddeninaclosetorcellar.Howaboutbringingbackthebright,leapingyellowflamesofrealwoodburninginarealfireplace?Howaboutbringingbackthefirethatsparkstheimaginationanddrawspeopletogetheraroundit?Howaboutbringingbackacentralhearththatbringsforthlight,warmth,andgoodfoodallfromthesamerenewablefuel?

FIGURE1.5.Amasonryheatercanbemadetofitanygivenspace.Thissoapstoneheater’sasymmetryfollowsthelineofthestairs.Noticethetwowood-storageareasinthestuccoedheatersupports.Sometimestheseopeningsinthebasealloweventhebottomofamasonryheatertobecomearadiatingsurface.PhotocourtesyofNewEnglandHearthandSoapstone.

Thehearthisthereasonforthehouse.Thathasnotchanged.Peoplehavemerelyforgotteneverythingafiredoes.Theycanonceagaintakethehearthseriously,however.Whenahouseisplanned,youcanstartwiththehearthandwatchwhatblossomsaroundit.Whenahouseisbuilt,itistoprotectthefirethatwillensurethewell-beingofthefamilywithin.Somewouldhaveusbelievethatafireplaceofanykindisanunnecessaryluxury.Butitistrulyoneofthefewnecessitiesofahouse.Takeawaythecentralvacuumorthewall-mountedflat-screenTV.Removethefurniture,intercoms,cabinets,counters,andelectricaloutlets.Skiptheindoorplumbing.Discardallthesethingsbutkeepawarm,centralhearthandafamilygatheredarounditwillstillfeellikethehouseisa

home.Theywillstillbeabletoexperiencerealcomfort,atruesenseofwell-being.

COMBUSTIONEFFICIENCY

Combustionefficiencyisawholeothermatterfromheatingefficiency.Combustionefficiencycompareshowmuchofthefuelwasburnedwithhowmuchwasavailabletobeburned.Formostcombustionappliances,thisnumberisverycloseto100percent.Thisisprettystraightforwardtounderstand.Naturalgas,forexample,isenormouslyflammable.Exposingittoasparkorflameinthepresenceofoxygenwillresultinallthefuelbeingburned.Thereexistonlyafewconditionsthatwouldpreventthefuelfrombeingcompletelyconsumed.Inthecaseofwood,whenitisburnedinanenvironmentofhighheatandgoodairsupply,it,too,willburnwithcombustionefficienciesapproaching100percent.Wood-burningequipment—thinkfireplacesandwoodstoves—thatstarveswoodofairand/orattemptstoburnitatrelativelylowtemperatureswilldoapoorerjobinthiscategory.

EnergyIntelligenceorEnergyEfficiency?

Thosewhoareplanningahome,roomaddition,orremodelingprojectarefacedwithmorethanjusttheissueofcomfort.Theyarealsofacedwiththesimplequestionofwhattypeofheatingsystemwillbeusedinthespace.Willtheyhaveaconventionalfurnace?Willtheyhavetoaddcapacitytoanexistingappliance?Whatisthebestwaytotakecareofheatingagivenspace?Invariably,thediscussionatsomepointturnstothequestionofenergyefficiency.Inthetwenty-firstcentury,itiseasytobelievewearereachingtheceiling,the

epitome,ofenergy-efficientdesignwhenitcomestoourmachineryandappliances.Thisfurnaceis80percentefficient.Wait,though,thisoneis90percentefficient!Ninetypercentefficient!Thatmeanswecouldonlyhopetoimproveitbyameasly10percentagepointsofefficiency.Knowingthatnothingisperfect,thereisno100percentefficientfurnace;sothis90percentefficientfurnaceisaboutasclosetoperfectashumanscaneverget.Right?Togainsomeperspectiveonthisnear-perfectheatingappliance,it’shelpfulto

takealookatjustwhatwemeanwhenwesaythatafireplace,furnace,stove,orotherheatingapplianceisXpercentefficient.Sheddinglightontheefficiencyrequireslookingagainatthelawsof

thermodynamics.Ipreviouslymentionedthefirstlawofthermodynamics:“Energyisneithercreatednordestroyed,onlyconvertedfromoneformtoanother.”Inmostheatingappliances,chemicalenergyboundinthefuelisconvertedtoheatenergy.Theefficiencyratingthatyouhearquotedforheatingappliancesiscalledthefirst-lawefficiencyofthatappliance.Thepercentagesignifiestheamountofheatextractedbytheappliancecomparedwiththeamountofheatit’spossibleforthatappliancetoextract.Inotherwords,thereisacertainamountofheatenergyavailableinagivenquantityofnaturalgas,wood,propane,orotherfuel.Ifonly10percentoftheheatavailableislostand90percentofitisdeliveredintothehome,theapplianceis90percentefficient.Thisiscalledfirst-lawefficiencybecauseitisonlydescribingtheprocessofextractingheatenergyfromthechemicalenergyboundinthefuel.Theprocedureofburningthefuelliberatestheheatenergylatentinthechemistryofthefuel.Noenergyiscreatedfromthereaction;energyisjustconvertedfromchemicalenergytoheatenergy.Theefficiencymeasuretellshowwelltheappliancedidatgettingthatenergyfromthefuelintothehomeasheat.Thefascinatingthingaboutfirst-lawefficiencyisthatitisverymisleading

whenviewedfromalargerperspective.Suppose,forexample,thatIuseapropanefurnace.SupposefurtherthatIphoneanewcompanytodeliverpropane,andtheyuseanarmytankfueledbypropanetohaulatrailertodeliverthepropane.Armytanksaverageabout0.5milepergallon.Ifthedeliverymanmakesaspecialtriptodeliveronlymypropanewithnootherstopsanddrives25milestomyhouse,heuses100gallonsofpropanetofillmy350-gallonpropanetank(50gallonstogethereand50togetback).IfIfactoredthisextra100gallonsoffuelintotheequationofhowmuchfuelittakestoheatmyhome,theefficiencywouldsuddenlydropseverely.Inthiscase,justusingmy90percentefficientfurnacetoburn350gallonsofpropanemeanstheheatfromallbut35ofthosegallonswasusedtoheatmyhome(.90×350=315).IfInowhavetoconsiderthat450gallonsofpropanewereactuallyusedintheprocessofgettingmyfuel,thenintermsofcalculatingtheefficiencyofheatingmyhome,450gallonswereconsumed—butIonlyreceivedtheheatof315gallons.Nowmyfirst-lawefficiencylooksverydifferent.Suddenlytheefficiencyisonly70percent.Obviously,nocompanydeliverspropanewithanarmytank,andtheoddsofa

deliverytruckmakingjustonestoponarouteareslim.Thepoint,however,isthatthefirst-lawefficiencymeasurementisonlyasmallfractionofthewholepicture.Anextensiveanalysisofwhatisrequiredtogetfuelintoahometellsamoreaccuratetaleofhowfirst-lawenergy-efficienttheprocessreallyis.Howmuchenergywasusedtofindthefuel?Howmuchenergyisusedtoextractthefuel?Howmuchenergyisusedtoprocessthefuel?Howmuchenergyisusedtoclean,restore,orpreservetheenvironmentaftertheextractionofthefueliscomplete?Howmuchenergyisusedtodeliverthefuelandmaintainthedeliveryinfrastructure?Thesesamequestionscanbeaskedregardlessofthechosenfuelandregardlessoftheefficiencyoftheend-useappliance.Alltheseenergycostsrelatedtogettingtheenergysourcetothehomeaddup

towhatiscalledtheembodiedenergyofthepropaneitself.Embodiedenergyisalltheenergyexpendedtoproduce,transport,andotherwiseprocessagivenitemtogetittoitsfinalusedestination.Computingthegrandtotalisamonumentaltask,thoughnotimpossible.You’dhavetoconsidertheenergyusedfortheinitialexplorationforthefuel(whichisusuallyfoundwithorextractedfrompetroleumornaturalgas)allthewaytothepointatwhichitisdeliveredtothehomeowner.

FIGURE1.6.Tiletrimdecoratesthisstuccoheaterinthecenterofahome.Noticethereisnovisiblefireorloadingdoorfacingtheroom.InEuropeintheolddays,heaterslikethisweresometimesfiredbyservantsthroughafuel-loadingdoorinabackhallwayorthekitchen.Withaheaterlikethis,theattractionisinthedesignandcoloraswellasthegentleheat,ratherthanthefireitself.PhotocourtesyofBiofire,Inc.

Youcandothesameexaminationwithanyfuel,suchaswoodformasonryheaters.Whenembodiedenergyisconsidered,the“efficiency”ofusingfossilfuelslikepropaneornaturalgasbecomesquestionable.Mostpeoplewhoburnwoodgettheirsupplyfromwithinashortdistanceoftheirhomes.Manyhomeownershaveafewacresofwoodsthemselves,whileothersgettheirwoodfromneighbors.Attheveryleast,mostpeopleheatingwithwoodgetthatwoodsomewherefromwithintheirmetropolitanarea,township,orcounty.Asasimpleexample,youmightorderyourwoodsupplyfromatreeservice

thatworksinnearbycity.Thetreeservicewasemployedbysomeonetoremoveatreeortreesfromaparcelofland.Theywerenothiredtoproducefuel.Thus,theenergyexpendedtodrivetruckstothesite,cutthetreedown,andloaditintotruckstobehauledawaywouldhavebeenexpendedevenifthewoodwasnotdestinedtobecomeacommodityforsale.Inthissense,thefirewoodthatbecomesavailablefromthistransactionisaby-product—essentiallywaste—ofthebusinesstransaction.

FIGURE1.7.Brickandstuccoarefinelyinterwoveninthiscentralheatingmass.Notehowtheoff-centerdooriscounterbalancedbythebrick-outlinednicheintheupperrightoftheheater.Thedateofconstructionispermanentlyetchedintoabrickintheleftcorner.PhotocourtesyofEnvirotechMasonryHeaters.

Thewasteproduct,woodfromthejobofremovingatree,hasadestination.Thedestinationisthehomeofthepersonwhohasamasonryheater.Youcouldthereforecounttheenergyneededtogetthetreefromtheinitialjobsitetothemasonryheaterhomesiteasthefirstembodiedenergyofthefirewood.Thismightinvolvetheburningof2or3gallonsofgasolineordieselfuelinthetruckthattransportsthetreeanddumpsitonthegroundatthedestination.Atthispointyou,themasonryheaterowner,takeovertheprocess.Youmay

useachainsawtocutthelogsintofireboxlengths.Thisprocessmightuseagallonorsoofgasolineandoilpercordofwood.Inaddition,youmayemployagasoline-poweredwoodsplitteranduseanadditionalgallonofgasolinepercordofwoodtosplitthefirewood.Inmostcases,therestoftheembodiedenergyinfirewoodconsistsofhumanenergyexpendedtomovethewoodwithcartsorwheelbarrows,stackthewoodundercover,andeventuallymovethewoodintothehouseforconsumptioninthemasonryheater.Clearly,theembodiedenergyinfirewoodisquitelow.Ifthewoodiscuton

thelotoftheplacewhereitwillbeburned,thetotalfossilfuelusemightbeacoupleofgallonsofgasolinepercordofwood.Ifanoutsideserviceisused,anadditionalfewgallonsofgasolineandsomemoreindividualhumaneffortmaybeinvolved.Animportantsidenotetothis,however,isthatfirewoodis(relativelyspeaking)easilyprocessedwithouttheuseofanyfossilfuels—infact,formostofhumanhistorytheworldranonawoodeconomy.Untilthetwentiethcentury,heating,cooking,andtheoperationofheavymachineryoftendependedontheburningofwoodratherthanfossilfuels.Itisnoteasilyimaginedhowwecouldeverdrillfor,extract,process,andtransportfossilfuelswithoutthefossilfuelsthemselves(except,ofcourse,bygoingbacktowoodenergyandsteamlocomotion).Asimilaranalysisof,forexample,propaneasaheatingfuelcanbedone.

Propaneisessentiallyaby-productofgasolineandnaturalgasproductioninthesamesensethatfirewoodcouldbeaby-productoftheworkofatreeservice.(Thereare,however,significantamountsofpropanethataremadefromcrudeoil.Thisprocess,sinceitintentionallyworkstocreatepropaneratherthanseparateitfromahigher-qualityfuel,wouldhavetoincludetheembodiedenergyofthatparticularrefiningprocess.)However,propaneisnotsimply

“skimmed”fromthegasolineornaturalgas.Rather,propaneitselfisonlyafractionofatotalofpetroleumgasesthatareseparatedfromeithergasolineornaturalgas.Oncetherawpetroleumgaseshavebeenseparatedfromtheprincipalfuels,

energy-intensiverefiningisstillneededtosecurethepropaneitself,whichistypicallyonlyabout5percentofthetotalpetroleumgasmixture.Oncethisrefininghasbeendone,thegasispressurized(whichliquefiesit)andputintotankertrucksfortransportationanddistributiontovariouspropanevendors.Thepropanevendorsthentransportthepropane,usingsmallertrucks,toindividualhomeowners.Manypropaneusersarefamiliarwithawintertimeroutinethatincludes

severalrefillingsofthepropanetankthroughouttheheatingseason.Thisoneoperationofrepeatedtruckdeliveriescouldusethesameamountofgasolineasisneededtodeliver,cut,andsplitfirewood.Theaddedenergyexpenditurestorefine,process,andinitiallydistributethepropane,therefore,givepropaneahigherembodiedenergyfigure.This,however,doesnotendtheconsiderations.Althoughknowingtheenergy

efficiencyofapplianceslikefurnacesisvaluable,atsomepointwemustalsofaceentropyagain.Earlier,Isummarizedthesecondlawasameasureofthetotalamountofenergythatisnolongerreadilyavailabletoperformanytaskoncetheinitialtaskiscompleted.Thisisjustanotherwayofrestatingtheheat-relateddefinitionofentropythatsaysthatheatalwaystravelsfromawarmareatoacoolerarea;itnevergoesfromcoolertowarmerwithoutanadditionalinputofenergy.Nowit’stimetorefinethisevenmoreandsimplystatethatentropyisthetendencytowarddisorder.Tounderstandhowtheentropylawgetsreducedtothisformulation,it’s

helpfultothinkaboutheatagain.Ifacontainerofhotairisopenedinthemiddleofa70°Froom,eventuallytheairinthecontainerwillcoolcompletely.Itobeysthesecondlawandreleasesitsheatintothelivingenvironment.Ingreaterdetail,whatwasanorganizedquantityoffast-moving(warm)airmoleculesmeldswitharoomfulofslower-moving(cooler)airmolecules.Inotherwords,ahighlyorganizedsetofmoleculeswithgreaterenergybecamelostinaseaofairmoleculesoflessenergy.Orderrepresentsenergystoredandabletobeused.Disorderrepresentsenergydispersedandnolongerabletobeused.Avasesittingonatablerepresentsstoredenergy.Ifthetableisremovedfrom

underit,thevasewillfall.Thatstoredenergybecomesheatreleasedasthevase

shattersonthefloor;thefracturingandbreakingreleaselittleburstsofheatfromfriction.Alesseramountoftheenergyisalsoreleasedassoundwavesintheair.Willthatvaseeverhavethesamepotentialenergyagain?Onlyifsomeonereassemblesit(expendsenergy).Anyonewhomaintainsahouseholdknowsthatorderineachroomrequiresenergyexpendedtoputeverythingwhereitbelongs.Iftheenergyisnotexpended,eventuallytheroomcomestodisorderasabookgetslefthere,adrinkingglassthere,anewspaperonthefloor,andadeadplantleafbythewindow.

FIGURE1.8.Hereisasimplestuccoheatercentrallylocatedinthelivingspace.Theopenstairwayallowstheradiantheattoreachallareasoftheroom.Noticethedryingracksabovetheheaterandaroundthechimneymass.PhotocourtesyofBiofire,Inc.

Thesameissueofdisorderversusordermustbeconfrontedinregardtoobtainingfuel.Currently,fossilfuelsareavailablefromvariouswellsorminesthroughouttheworld.Inacoalmine,forexample,theeasiest(mostorderly)coaltorecoverisclosesttotheinitialexcavations.Asthecoalgetsused,excavationsneedtobedeeperandmoreenergyisneededtogetthecoaloutofthemine.It’sasifyoustartedconsumingallthefoodinthekitchenwithoutreplenishingthesupply.Eventually,therefrigerator,freezer,andkitchencupboardswouldbebare.Next,youhavetostartwalkingtothepantryuntilthoseshelvesarestripped.Nowyouhavetowalkdownintothebasementtothelong-termstoragefreezer.Theamountofeffortforeachmealisincrementallyincreasing.Whenallthatfoodiseaten,thereisnofoodinthehouse,andyouwillhavetoexpendevenmoreenergytogetfoodfromagardenorbywalkingtothegrocerystore.Ifthegrocerystorestocklikewisewasnotreplenished,eventuallyyoumighthavetogotothenexttownorcountytofindfoodforyournextmeal.Asthe

easilyobtained,highlyorganizedstoresareconsumed,moreandmoreenergyisrequiredtogetmorefoodofthesamequality.Thisisthereal,hiddencostoffossilfuels.Astheyareconsumed,andsincetheyareneverreplenished,itwillforevergetharder,moreexpensive,andlessrewardingtomineordrillforit.It’sacertaintythatiffossilfuelscontinuetobeexploitedatcurrentrates,theywilleventuallyfalloutoffavorduetoenormouslyrisingcostsbroughtaboutbytheincreaseinentropy—thelossoforderas(relatively)convenientsuppliesareconsumed.Thiswillhappenregardlessofenvironmentalissuessuchasclimatechange,pollution,andwaterquality.Thisiswhatmakeswoodsuchanattractiveoption.Woodwillalwaysbe

renewableaslongastreesarereplantedandthesunisoverhead.Withsimplemanagementandconscientioususeofefficientwood-burningequipmentlikemasonryheaters,peoplecanheatahomeandbakethefamilybreadjustaseasilyonehundredyearsfromnowastoday.Thebeautifulthingaboutnatureisthatitalwaysreplenishestreesandplantsinatimeframecommensuratewithhumanlifespans.

TheDemiseoftheFireplaceAswemoveforward,therewillcontinuetobeothertechnologicalsolutionsforheatinghomesthatrelynotonsimplesciencelikestoredsolarenergy(eitherdirectlyorintheformofwood),butonnewdiscoveries.Forayswillcontinueintotheuseofhydrogenfuelcells.Nuclearenergy,bothfissionandfusion,willremainonthedocket.Coalgasification,wind,hydroelectric,theuseofsea-wavemotion,andawholehostofotheralternativeswillberesearched,refined,tested,andimplemented.Wecannotevenguesswhatourprimaryenergysourcesmightbeinonehundredyears.

Whatispredictableisthattheseeffortswillmainlybetowardfindingwaystocentralizeenergyproduction.Whenlargecorporationsandgovernmentareinvolvedintheprocess,itisanearcertaintythatsimple,home-basedtechnologybasedonusingstoredsolarenergy,freeforeveryonetoreceive,willnotbetheprimaryemphasis.Thereisnowaytotax(atleastnotyet)solargainortreesgrownonone’sownproperty.Thereisnomoneytobemadebyenergycompanieswhenpeoplefueltheirhomesusingwood.Peoplewillcontinuetobetoldthatcentralizedenergyproductionisintheirbestinterest.

Centralizedenergyproductionseemslikeagoodideainmanyways,andcertainlydidtomillionsofpeopleearlyinthetwentiethcentury.Inexpensive,easilyobtainedfossilfuels,deliveredtothecustomer’shouse—firstbytruck,thenbypipeline—madeperfectsense.Thereisaperceivedincreaseinqualityoflife,asthechoreofsecuringourownfueliseliminated.Wecertainlyfeelprosperoushavingheatwithouthavingtothinkaboutit.ItonlytookonehundredyearsforAmericancitizenstobecomedependentonsomeoneelsetomakesurethereisheatinthehouse.Thedependencyonfossilfuelshasthusnearlykilledthetraditional,open,

wood-burningfireplace.Itneverwasafantasticheatingappliance,andnowitis,generally,anenergydrainonanotherwiseenergy-efficienthouse.Todaythefireplacehasbeenalmostentirelyrelegatedtothecategoryofsuperfluous,mood-settingdevices.Becausefirestillpullsattheheartstringsofhumanbeings,fireplacesremainasought-afteramenitytonewhomesthroughoutNorthAmerica.Thisamenity,however,willslowlydisappearfromhouseseverywhere.Already,generationsofpeopleareraisedinhomesandapartmentswithout

anytypeoffiretoviewatall.Neitheragasnorwood-firedhearthexistsinvastnumbersofresidences.Newerhomestendmoreandmoretohavegasversions.In2005,accordingtotheHearth,Patio,andBarbecueAssociation,gasappliancesoutsoldwood-burningversionsbyafour-to-oneratio.2Alookatthehearthindustryrevealsthatwhenpeoplearen’tinterestedinusingafireplaceasaprimaryheatsource,itbecomesanoveltyitem.Designersarefreedfromtheconstraintsofmakinganefficientheatingappliance.Moresignificantly,theyarebeingfreedfromtheconstraintsofproducingaplacetohouseabulky,woodfire.Therefore,theyaremaking“fireplaces”thatmoreresembleaflat-screentelevisionsetthanafireplace.Indeed,somehangonthewallandcomeinimaginativeshapesandsizes.Manyconsumersfindthefireofagasappliancetobeunsatisfying,however.

FIGURE1.9.Thismasonryheater’scrisp,squarecornersanduniformcoursesofstoneproducecleanlinesthatcomplementthestraightlinesoftheoverheadbeamsandthelattice-likewoodenwallsurface.Noticehowthesamestoneworkisinthestairwayandfoyerbeyond,successfullyblurringthelinebetweenwheretheheaterstopsandtherestofthespacebegins.PhotocourtesyofTemp-CastEnviroheat.

Havingaplacetohouseafireinahome,then,isevolvingintosimplyanaestheticchoice.Ifthefireplaceisn’tfunctionaloritbecomeslessandlesssatisfying,itwillgracefewerandfewerhomes.Thetraditionalfireplace—anopenfireboxcontainingawoodfire—willnotendurethisslowevolution.Tobesure,therewillalwaysbesomepeoplewhowillinsistonhavinganopen,wood-burningfireplace.Butthefuturewillbeownedbythefireplacesthatsatisfyeithertheaestheticdemandsofconsumersorfunctionalheatingdemands.Thosethatsatisfybothartandfunctionwillleadtheway.Inthatsense,then,theopenfireplacewillcontinuetodiewhilethemasonryheaterwillsurviveandthriveasmorepeoplebecomeacquaintedwithit.Masonryheatersaretheonlywood-burningappliancesthatblendimaginationwithsuperiorefficiencyandheatingability—nottomentionaplethoraofotherbenefits.

Ascentralplannersandbigenergybusinesseswrestlewiththepainsofenvironmentalconsiderations,increasingworldwideenergydemand,decreasingandlesseasilyobtainedfossilfuelsupplies,risingenergycosts,anddozensofotherobstacles,individualsshouldbecomeawarethatitispossibletoreturntosomethingsimplerandmorebasic.Youdon’thavetospendallyourfreetimechoppingwoodtobemoreself-sufficient.Youdon’thavetorelyonotherstosupplyenergyforheating.Youcanalwaysreturntothesoundfundamentals.

FIGURE1.10.(a)Anheirloom-quality,one-of-a-kindmasonryheatercanservegenerationstocome.Hereisacustom-designedTulikivisoapstonemodelfitcleverlybetweentwolivingspaces.(b)CarvedinthedarkbandisaquotefromGoethe:“Whateveryoudreamyoucando,beginit.Boldnesshasgenius,powerandmagicinit.”PhotoscourtesyofWarmStoneFireplacesandDesigns;copyrightMikelCoveyPhotography.

FundamentalsItiscertainlytruethatweneedastrongfoundationonwhichtobuildanything.Thisistrueforeitherahouseoraphilosophy.Ifahome’sfoundationsuffers,thehomewillsuffer.Ifthefoundationalbeliefsofaphilosophyareshakyorquestionable,it’shardtosubstantiatetherest.Thefundamentalsalwayshavetobeinplaceforanythingtoprosperorthrive.Thefundamentalsofahousearerelativelyfew,buttheymustexistbeforeany

amenitiesareworthconsidering.Afterall,whatwouldbethepointofinvestingthousandsofdollarsinanentertainmentsystemif,say,theroofissubpar,leaks,andwillthendestroythoseelectronics?Theshortlistofhousefundamentalsincludesthefoundation,framing,insulation,exteriorveneer,roofing,windowsanddoors,floors,andheatingsystem.Inessence,thefundamentalsofahousearethosethingsthatmakeitaviable,long-termplacetolive.Everythingelsethatmightgointoahouseisanamenity.Thoughmodern

culturewouldclaimthatindoorplumbingandelectricityarealsofundamentals(and,indeed,localbuildingcodesoftenrequirethem),theyarenot,inthestrictsense,fundamentals.Withoutafoundation,thehomewilldeteriorateandcollapseprematurely.Withoutframing,thereisnowaytoholduparooforsidingtokeepoutweather.Withouttheroofandsiding,thereisnolongevitytotheframingorprotectionfrombasicweather.Withoutthewindowsanddoors,thereisnoentranceoregressandnolightwithsimultaneousprotectionfromtheelementsandbasicsafety.Withoutfloors,youcannotwalkaroundinthehome.Withoutaheatingsystem,winterswouldbe,practicallyspeaking,unlivable.Finally,withoutinsulation,heatcannotberetained.Ifyouthinkaboutquality,durability,andthepotentialheirloomnatureofa

home,masonryheatersbegintomakesense.Woodhasbeenareliablefuelforever.Thevariousapproachestohomeheatingdevelopedoverthelasthundredyearsrepresentabliponthescaleofhumanhabitationonearth.Wecanmarvelatelectricheatpumps,bragabout90percentefficientfurnaces,orrevelinthesensuousnessofwarmfloors.Butnoneofthetypicaltechnological

heatingsolutionsaroundtodaycanbeconsideredheirloom-qualityandfundamentalinnature.Thereisnomistakingthatcoalreserveswilldiminish,thatoilreserveswill

decline,andthatallotherfossilfuelsourceshavelimitedsupplies,especiallyconsideringanever-increasingpopulation.Ofwhatvaluewillwarmfloorsbewithnoelectricitytopumpthewater;orelectricitysoexpensivethatyoudarenotuseit?Ofwhatvalueisa90percentefficientfurnaceasoilreservesgrowincost,loseavailability,andeventuallydisappear?Fossilfuelsarenotfundamentals.Theyareexoticmaterialswithtremendous

energystorespersmallunit.Fundamentalsaremundane,normal,andrelativelyeasytofindorcloseathand.Fundamentalsarethosethingsonwhichwecanalwaysdepend.Fundamentalslikewisecanberestoredtogreatquantityeveniftheyaremismanagedanddepletedatfirst.InOhio,applesandcornarefundamentalfoods,butmangoesandkiwisareexotic.Waterisafundamentaldrink,whileGatoradeisnot.Cottonisafundamentalingredientforcloth,whilepolyesterisexotic.Woodisafundamentalfuel,whileuraniumisnot.Forabrieftime(years,decades,orevencenturies),wecanbaseaneconomy,

production,distribution,andlifeingeneralonthesupplyofexoticmaterials.Suchasystemisdestinedtofail,however.Sometimesitispossibletoseetheendofsuchasystemcoming;sometimesithappensveryquicklyandunexpectedly.Sometimesitsendcomeswithunexpectedconsequences.Whatwillalwaysbearound,however,whentheexoticsfail,arethefundamentals.Amasonryheaterisanheirloomheatingsystem.Itisbuiltwithmaterials

destinedtolastcenturies.Itisbuiltwithmaterialsthatarecommonandmundanelikeclay(bricks),stone,moreclay(mortar),andsand,lime,andPortlandcement(commonmortar).Itisbuiltwithadesignthatcannotloseefficiencyovercenturies.Itisbuilttousefuelthatcanberegenerated(wood).Thiscombinationassuresthataslongasthere’saroofonthehome,peopletoliveinit,andtreesnearby,therecanbeheatandcomfort.Thesamecanneverbesaidforsystemsthatdependonendlessinfrastructureandpoliticalrelationships.

PASSIVERESISTANCETOFOSSILFUELS

InaruralareanotfarfromAnnArbor,Michigan,sitsahomenestledintotheearth.Fromtheroad,itcanbarelybeseen;itratherblendsintoitssurroundings.Aquarter-miledrivewayoffadirtroadbringsyoutothisspecialhouse,builtinaspecialway,andoccupiedbytwospecialpeopleandtheirmasonryheater.

JoanPaskewitzandTomTuerresidehereinoneofthefewpassivesolar,earth-bermedhomesinsouthwesternMichigan.Joanisaphysicaltherapistatalocalhospital,andTomretiredawhilebackfromacareerinaerospaceengineering.Whentheytalkabouttheirhouse,however,thetwosoundlikesolararchitects.Joansaysit’scrazythatpeoplerarelybuildwiththeeffectsofthesuninmind.“Theyshouldpassalawthateveryhouseneedstohaveitslongaxisfacingsouth,”shequips.“Justthinkhowmuchenergywouldbesavedbydoingthatonething!”TomandJoandesignedtheirhomeinthelate1990sandtooktheirplantoan

architecttohaveitdrawnaftertheyhaditallfiguredout.Thehomehasanabundanceofsouth-facingglass(triple-panewindowswithbuilt-insolarshutters).Joanappreciatestheexpansesofglassforkeepingthehomefulloflotsoflighteveninthecloudywinter.Themainfloorisapoured,insulatedslabwithgreentilefinish.Thefirst-levelnorthwallisentirelybermedwithearth,asareportionsoftheeastandwestsides.Theceilinghas12inchesoffiberglassinsulation,givingitaninsulationvaluethatexceedsR-40.Carefullycalculatedsouth-sideoverhangsinviteallthewintersunintothehomebutexcludethehotsummersun.

FIGURE1.11.Althoughitlooksalotlikeatypicalhouse,theTuer/Paskewitzresidenceisafunctionalpassivesolarandearth-bermedhome.PhotobyTomTuer.

Theresultofthecarefulplanningisthat,whenthesunshinesinthewinter,itstreamsdelightfullythroughtheglazingandwarmsthemasonryfloor.Thefloorsoaksupthatfreeheatandstoresitforslowreleaseovertime.Thehouseiscomfortablyheatedbythesun.Thewholehouseisamasonryheater,inthatsense.Joanpointsoutonepotentialproblemwithpassivesolar:“Wedon’tgetsunshineallthatofteninthewinterinMichigan.”Fortunatelyforthem,they

alsoinstalledawood-firedmasonryheaterin2001,notlongaftertheymovedintothehouse.TheirsisaFinnishcontraflowheaterwithmultihued,splitgraniteastheexteriorfacing.Tomsays,“Ialwayswantedagranitefireplace.Weenjoytheconstanttemperature—howitisveryslowtocoolallthatgranite.”Inotherwords,whenthesunisn’tshininginthewindows,itshinesfromthemasonryheater.Whenthesunisshininginthewindows,theycanforgotheuseoffirewood.It’saperfectsymbioticrelationship.Tomexplains,“Unlesswe’vegottenalotofsun,wealwaysenjoyeating

breakfastwhileenjoyingafire.Theeveningfireisoptionaldependingonthesunshineweget.”Thepairhasfewdisparagingwordsaboutthemasonryheater.Joancallsit

“beautiful”and“functional,”andmostimportantlyaddsthat,“Theheatisverynice.”Shedoespointout,however,thatregularlyhaulinginwooddoes,inevitably,meanthatsomedirtisbroughtinthehouseaswell.Shealsonoticessomeashgetsinthehousefromtheoccasionalopeningofthefireboxdoororfromcleaningashoutoftheashpit.Tomlikesitforitsgranite,foritscomfort,andbecauseheknowsithaslowemissions.

FIGURE1.12.Agranitemasonryheaterservesasthesunshinewhenthe

realsunhidesbehindcloudsattheTuer/Paskewitzpassivesolarresidence.StovebyMasonryHeaterStore,LLC;stoneworkbyPeterSkove;photobyNancyMatesz.Astothejobofsplittingandstackingfirewood,Tomsaysheenjoysit,“both

forexerciseandforthesenseoforderlinessandsatisfactionthatcomesfromcarefullystackingaheapofwood.”Hestacksthewoodonpalletsinasimplewoodshedwithopendoorwaysonboththeeastandwestends“soIcanemptyitfromonesideandfillitfromtheother.”Hetriestohaveallhiswoodsplitforayearbeforefeedingittothemasonryheater.Althoughthepassivesolarfunctionofthehouseandthemasonryheater,asa

team,aretheprimaryheatsourceforthehouse,JoanandTomalsohaveageothermalheatpumpasamechanicalbackupsystem.Theydouseoneortwozonesofthissystemprettyregularly,butonlyovernightwhentheelectricratesarelower;onekeepsafardistant(frombothsolarandthemasonryheater)bathroomfloorwarm,andtheotherkeepsaworkshopatareasonabletemperature.“Otherwise,”saysJoan,“Ican’trememberthelasttimeweusedthefloorheatingduringthedayatall.”Sheprovesitbyshowingelectricbillsoflessthan$80inJanuary.“Andthatincludestheheatpump,hot-waterheating,andtheoperationofthewellpump.”Likemanymasonryheaterowners,TomandJoanappreciatetheheaterforits

guaranteeofsecurity.Theyrecallawinterperiodwhentheylostelectricpowerforabouttwenty-fourhourswhiletheyhadeightguestsstayingwiththem.Theylitcandlesforlight,andseveralpeoplesleptinthelivingroomnearthemasonryheater.Inanall-electrichouseliketheirs,poweroutagemeantnoconventionalovenorstove,either.Theywerestillabletofeedtheirfriendsham,potatoes,andvegetablescookedintheupper-chamberbakeovenofthemasonryheater.Heat,food,andlightallcamefromarealfireandsimple,localfuel.There’snothingmoresecurethanthat.Alittleplanninggoesalongway.TomandJoanplannedforahousethatdid

notdependonfossilfuels.Theychosethepathofsimpletechnologyandfreeenergy.Theirhousecollectstheheatofthesun,anditbasksinthedependableheatofapieceofthesun—amasonryheater.Theirhomeisproofthatpassivesolardesignandamasonryheatertogethercanmakeahousesolar-heatedevenincloudyMichigan.

FIGURE2.1.Amodern-daykachelofenwithtraditionalelementsgracesthisConnecticuthome.Theflutedtilesandcylindricalelementwithbraidsandrosettesharkbacktoanothercentury.Yetthisheaterboastsacomputer-controlledcombustionairsupplyandanefficientinternaldesignfacilitatedbybothacraftsman’sexperienceandcomputermodeling.PhotocourtesyofNewEnglandHearthandSoapstone.

CHAPTERTWO

ABriefHistoryofFireandHotRocksinNorthAmerica

Thoughhumansprobablyhadlittle,ifany,controloverfirehalfamillionyearsago,thereislittledoubttheymadeuseofheatstoredinrocks—evenifonly,likeacat,totakeanapinawarmplace.Oncecontroloverfirewasthenorm,storageofheatwasanaturalresult.Youcaneasilyimagineafamilyofcavedwellersbecomingecstaticastheyrealizethepossibilities:Theycanchargerockswithheatbysituatingthemaroundthefire,burythehotrocksjustalittlebelowfloorlevelinthesleepingarea,andenjoyaheatedbedallnightlong!Perhapsthesewerethefirstheatedsleepingareas—probablyexistingacoupleofhundredthousandyearsago.Similarly,nativepeoplesofmanylandshavefromtimeimmemorialheatedrocks,thenputtheminpotswithwater,vegetables,andmeat,tocookastewormakeateawhenit’simpracticaltohavethepotdirectlyoverthefire.Ofcourse,evenuptotheearlytwentiethcentury,peopletookrockswarmedinafireoronastoveandusedthemtowarmtherideinabuggyorwarmthefeetinbed.

Icouldsuccessfullyargue,usingscenarioslikethese,thathumanshaveusedmasonryheatersforhundredsofthousandsofyears.It’salittledisingenuous,however,toputrockswarmedbythesunoracampfireinthesameleagueasengineeredheat-retainingmasonryheaters.Muchofthedelightisthesame,butthehumanthoughtgoingintothedeliberateplanningforthestoredheatis,obviously,different.

TheHiddenAmericanExperienceIamoftenaskedbynewacquaintanceswhatmybusinessis.WhenIdescribemasonryheaters,Iusuallyseeoneoftworesponses.Inthefirst,theinquiringperson’seyesglazeoverandhedeclaresthathehasneverheardofsuchaheater.Often,however,theinquisitiveindividualinsteadgetsadreamylookinhereyesandthensays,“Oh,yeah,Irememberthosetilestoves.Weusedtoseeonewheneverwewenttotheartmuseum!”

Whenmywife,Nancy,wasachild,herelementaryschoolclassannuallytraveledtotheToledoMuseumofArtinToledo,Ohio.Asyoungchildrenwilldo,theyoftengottiredandratherboredwithwalkingthewide,marbleaislesandgazingendlesslyatframedartwork.Therewasalwaysasenseofexcitementfortheclass,however,whentheywenttowhattheycalledthe“SwissRoom.”There,asthecenterpiece,sitsatall,highlyornatetilestove.Themuseumpiece,whichisbelievedtohavebeencreatedinthelatenineteenthcentury,wasdesignedinthestyleofSwissoriginalsfromtheeighteenthcentury.TheToledotilestoveisdecoratedwithscenesfrommythology,legend,and

theBible.Whatreallyattractedthechildren,however,wasthesmall,singleseatthatispartofthestove.Onebyone,eachstudentwouldbeallowedtoclimbthetwotilestepsandsitonthe“throne”—whichofcoursewouldhavebeenthewarmestplaceinthehousewhenthestovewasinuse.Inthiswayhundreds,ifnotthousands,ofpublicschoolstudentsinnorthwesternOhiowereandareexposedtotheconceptofmasonryheaters,thoughoftentheteacherattendingmaynothaveanunderstandingofhowsuchaheaterreallyfunctions.Unfortunately,today,atleastinthatmuseum,peoplearenolongerpermitted

toeventouch,letalonesiton,thetilestove.Althoughitiseasytounderstandthedesiretopreservesuchartwork,itmeansthatobserversnolongergetamoremeaningfulunderstandingoffunctionalart.OthermuseumsthroughoutNorthAmericaalsohavehistorictilestoves,and

millionsofstudentshaveseenthem,thoughitmaynotregisteruntiltheyrunintosomeonewhoactuallybuildsthemtoday.TheAdirondackMuseuminBlueMountainLake,NewYork,hasatilestove,andtheAmericanSwedishInstituteinMinneapolis,Minnesota,hasseveralSwedishkakelugns.TheMetropolitanMuseumofArtinNewYorkCityhasaveryornatestovefromNuremberginitscollection.

FIGURE2.2.TheSwissRoom(detailoftilestove),ToledoMuseumofArt.Thistilemasonryheaterhasbeenvisitedbyhundredsofschoolchildrenoverthedecadesithasbeenondisplay.Notlongago,childrencouldclimbthestepsandsitonthe“throne,”whichwouldhavebeenthewarmestseatinthehouse.Thisisalate-nineteenth-centuryreplicaofaneighteenth-centuryoriginal.PhotocourtesyofPhotographyIncorporated,Toledo,Ohio.

ButmuseumsarenottheonlyplacesthatmasonryheatersareseenbymillionsofmodernUSandCanadiancitizens.Inthefilmversionofoneofthebest-lovedmusicalsofalltime,TheSoundofMusic(1965),thechildrenoftheBaronvonTrapp(playedbyChristopherPlummer)settledownontherugintheparlortolistentotheirgentlemanfatherplaytheguitarandsingwithatilestoveinthebackgroundagainstthewallbetweenhimandMaria(playedbyJulieAndrews).Morerecently(2006),anobservantmoviegoercouldseenotonebuttwobeautifultilestovesintheluxurioushomeofCrownPrinceLeopold(playedbyRufusSewell)inthefilmTheIllusionist,setinVienna,Austria,in1900.

FIGURE2.3.AkachelofensimilarinstyletotheoneinTheSoundofMusic.PhotocourtesyofVintageElements,Greenwood,SouthCarolina.

FIGURE2.4.OneofthekakelugnseeninthemovieTheIllusionist.©2005IllusionistDistribution,LLC.AllRightsReserved.PhotousedbypermissionofIllusionistDistribution,LLC.

DespitethefactthatNorthAmericahasnocenturies-longestablishedtraditionofmasonryheaters,somechildrenandadultshaveatleastseentheminmuseumsandmovies.PerhapstomostAmericanssuchstovesarelikeavaguelyrememberedlandmarkonaroadtripthatgoesunnoticeduntilsomeonepointsitoutlater.Oftenwedon’tnoticeotherwiseobviousobjectsifwe’renotlookingforthemorareintentonotherobservations.ChildrenareoftenintroducedtotilestovesthroughthestoryofHeidi,the

youngSwissgirlwhogoestolivewithhergrandfatherintheSwissAlps.Heidiwaswrittenin1880byJohannaSpyri,aSwissauthor.Lateinthestory,Heidiandhergrandfathermovedownfromthemountains

intoanold,run-downyetonce-splendidhomeintown.Thehomehasbeenabandoned,andthegrandfathertakesituponhimselftopatchupwhatisleftandmakeithabitableforthetwoofthemratherthansubjectHeiditothestruggletosurviveawinterinthemountains.JohannaSpyriwrites:

FIGURE2.5.HeiditeachesPetertoreadwhileGrandfatherlistens.Atilemasonryheaterkeepsthemwarm.IllustrationbyTroyHowell,fromthe1945editionofHeidi.

Thefourwallswereallstanding,thedarkwoodpanelsshowednotabreak,andinonecornerstoodahugestove,reachingalmosttotheceiling,andonthewhitetileswerebigbluepictures.Someshowedoldcastles,withtalltreesallround,andunderneathahuntsmanpassingwithhisdogs.Anotherpictureshowedapeacefullake,underwide-spreadingoaks,withafishermanstandingbyitandholdinghisrodfaroutoverthewater.Therewasaseatallroundthestovesothatonecouldsitdownandstudythepictures.ThisatoncetookHeidi’sfancy.Assoonasshecameintotheroomwithhergrandfather,sherantothestove,satdownonthebench,andbegantolookatthepictures.Butasshemovedalongontheseatandcamebehindthestove,somethingnewoccupiedherwholeattention;inthequitelargespacebetweenthestoveandthewallfourboardswereplaced,likeabinforapples.Buttherewerenoapplesinit;thereactuallylayHeidi’sbedexactlyasithadbeenupontheAlm;athickbedofhay,withthelinensheetandthebagforacoverlet.Heidishouted:

“Ograndfather,hereismybedroom!Oh,howlovely!”1

Heidi’sgrandfatherhasprovidedHeidiwiththepremiumspottosleep—closetothemasonryheater,which,inthiscase,isatilestove,thetilesofwhichhavebeenpainstakinglypaintedwithquaintcountryscenes.AfewparagraphslaterSpyriwritesthat,“Heidisleptsoundlyinhercornerbythestove,”asyoumightimagine.Mymemoryreeledin2008whenIparticipatedinthereconstructionofaneighteenth-centurySwisstilestovehand-paintedwiththeverytypesofscenesJohannaSpyridescribes.Theprojectstovehadpicturesinrustredinsteadofblue.Nevertheless,thestoryofHeidicameclosertohomeanditbecameeasiertoimagineyoungchildrengatheringaroundthestovetostudytheintricatepicturesandsoakupthewarmth;perhapschildrenacenturyagosleptintheirstrawbedsclosetothisstoveaswell.

FIGURE2.6.(a)Aneighteenth-centurytilestovethathaspaintedillustrations.(b)Thisclose-upofatiledepictsjustthekindofscenesJohannaSpyridescribedinHeidi.ProjectbyNewEnglandHearthandSoapstone;photosbyTimothySeaton.

ThecasualreaderofHeidiunderstandablypassesoverthedetailsofthisaccount.Butitisinterestingtonotethattheauthorofthisnovelmatter-of-factlydescribesacommonarchitecturalfeatureofhercountryandhowitwasused.Forexample,shestatesthata“seatranallroundthestovesothatonecouldsitatone’sease”andfollowedwiththeconfirmationthatonewouldsleepwellbythestove.ThepeopleoftheOldWorldknowhowtolivewithamasonryheater,andNorthAmericahasbeenletinonthesecret,butheatershavenotreceivedmuchattention.Lesswidelyknownisthenineteenth-centurystorybyEnglishnovelistLouise

delaRaméetitled“TheNurembergStove.”Thetaleisaboutapoverty-strickenfamily.Thefather,growingdesperate,sellsthefamily’stilestove.Everyoneispained,butAugust,aboyofabouttenoreleven,isheartbroken.Thestorycentersontheeventsthatoccurasthestoveistakenaway.Thebeginningofthestorydescribesthemasterpiece:

Atthetopofthechamber,sendingoutwarmthandcolor,wasatowerofporcelain,surmountedwitharmedfiguresandshieldsandagreatgoldencrownonthesummitofall.Itwasastoveof1532,thehandiworkofthegreatpotter,AugustinHirschvogel.

Thestove,nodoubt,hadstoodinpalacesandbeenmadeforprinces;hadwarmedthecrimsonstockingsofcardinalsandthegold-broideredshoesofarchduchesses.Itwasarightroyalthing.Yet,perhaps,ithadneverbeenmoreusefulthanitwasnowinthispoor,desolateroom,sendingdownheatandcomforttothetroopofchildrentumbled

togetheronawolfskinatitsfeet.

FIGURE2.7.Anineteenth-centurytilestovewithcolorandshapemuchliketheoneillustratedinHeidi(1945edition).PhotocourtesyofVintageElements,Greenwood,SouthCarolina.

FIGURE2.8.InthisscenefromRamée’s“TheNuremburgStove,”Augustisheartbrokentohearthathispieceofthesunwillbetakenaway.IllustrationbyF.M.McAnelly.

Laterourprotagonist,August,entertainshisbrothersandsisterswithartworkdrawnastheysitneartheheater:

Theywereallsohappy;whatdidtheycareforthesnowoutside?Theirlittlebodieswerewarm,andtheirheartsmerry;andAugustcried,ashelookedatthestovesheddingitsheatonthemall:“Oh,dearHirschvogel,youarealmostasgreatandgoodasthesun!No,youaregreaterandbetter,becausehegoesawayallthesedark,coldhours;butyou—justabitofwoodtofeedyou—andyoumakeasummerforusallthewinterthrough!”2

FIGURE2.9.InSeredy’sTheGoodMaster,Kateclimbsthe“beehive”tohideintherafters.Childrenandparentsalikecanbeexposedtomasonryheaterswithoutevenrealizingit.IllustrationbyKateSeredy.

Andsoitis.Amasonryheater,confirmedagesago,isa“pieceofthesun.”Anillustrationfromthebookisseeninfigure2.8.AheateralsomakesanappearanceinKateSeredy’sTheGoodMaster.This

1935bookisaboutaHungarianfarmfamilyandtheheadofthehousehold(thegoodmaster)whodealssowellwithallthegoings-on.WehearmainlyaboutJancsi,theson,andKate,Jancsi’scousinfromthecitywhocomestovisit.Inchapter2isthestoryofthetomboyKatewhomischievouslyhasclimbedintotheraftersabovethefamilyandissubsequentlyaskedhowshegotupsohighandwhyshewillnotcomedown:

“Iclimbedonthatbigwhitebeehiveinthecorner,butit’shotnow,[Mother]madeafireinit,”saidKate.Shemeantthestove.Itdidlooklikeabeehive,squattinginthecorner.Therewasabencharoundit.Jancsilovedtocuddleonthebench,proppinguphisbackagainstthewarmsideofthe“kemence.”

FIGURE2.10.ThetraditionalkemencefromHungarywasoftenapoorman’sheater,fueledwithgrassesandscroungedsticks.ThisisthesametypeofheaterdescribedinTheGoodMaster.FromDavidLyle,TheBookofMasonryStoves,p.90.

“Well,nowyou’llstaythereuntilthe‘beehive’coolsdown.Jancsi!Mother!Iforbidyoutotakeherdown.Shecanstaythereallnight!”saidFather.3

Onceagain,wearetoldofamasonryheaterwithbenchesarounditthatafamily,andespeciallychildren,leanagainsttostaywarm.It’sa“beehive”thatwillstaywarmallnight,preventingthemischievousgirlfromcomingdownfromherperch.Thesearethreesplendidchildren’sstories,setinthreedifferentEuropean

locations.WehearabouttheHungariankemence,aSwisstilestove,andaGermanporcelaintilestove.Theyarevastlydifferentdevices,butallkeeptheiryoungcompanionswarmwithgentleheat.Thekemencewasalmostalwaysapeasants’stove—aminimalstuccoed“beehive”thatwasmoreaboutfunctionthanform.Ontheotherendofthespectrumisthehighlyornateporcelainstovedepictedin“TheNurembergStove,”which“nodoubt,hadstoodinpalacesandbeenmadeforprinces,”4ornateasitwas.

FIGURE2.11.HereisamodernversionofKateSeredy’s“beehive.”ThiscustomsoapstoneheaterinFinlandsportsaheatedbenchandacarvedfishonthemantel.The“beehive”shapecontainsthefireboxandasecondarychamberaboveathroat.Theexhausttravelsfromtheupperpartofthedomedownintotheheatedbenchesandthenupintothetallrectangularelementsinbackbeforeexitingintothechimneyflueatcenterleft.PhotocourtesyofTulikiviCorporation.

AndthenthereisHeidi’sstove,withquaintpicturesofcommonscenes—somewherebetweenhighlyornateandbasicallyfunctional.Differentcountries,differentappearance,differentconstruction,butalltheheatersgivethesamereliableheatinthecoldregionsoftheworld.SincevirtuallyeverycoldnorthernEuropeancountryhasastrongheater

tradition,it’ssomewhatsurprisingthatmasonryheatershave,historically,notbeenpartoftheNorthAmericanscene.Thelogcabinwasatraditionalwayof

buildinginthesesameEuropeancountries,andthismethodofconstructionreadilytookholdinNorthAmericaasimmigrantsharvestedthevastexpansesofbothhardwoodandsoftwoodforests.Remarkably,acompanionconstructiontechnique—themasonryheater—nevergotafoothold,thoughsomewerebuiltinscatteredlocationsbynow-unknowncraftsmen.Thesheeramountofforestedland,andthereforefuel,mitigatedtheneedfortheenergysavingsthatwouldresultfromusingamasonryheater.Anditwaseasiertohaulametalstovethantonsoftileandbrickwhenpioneersspreadoutacrossthecontinent.

FIGURE2.12.PerhapsthisiswhatMarkTwainthoughtwas“thepolishedwhitetombthatstandsloftyandheartlessinthecornerandthinksitisastove.”PhotocourtesyofVintageElements,Greenwood,SouthCarolina.

OnhistravelsthroughEurope,MarkTwainexperiencedandtooknoteofmasonryheaters.Interestingly,asaskepticalAmerican,heinitiallyfoundthemtoberatherpathetic.Inhisessay,“AnAustrianHealthFactory,”hewritesofhis

stayinAustria,

ButasaruleIstayinandtrytogetwarm.Andwhatisthereformeans,besidesheavyclothingandrugs,and

thepolishedwhitetombthatstandsloftyandheartlessinthecornerandthinksitisastove?Ofallthecreationsofhumaninsanitythisthingisthemostforbidding.Whetheritisheatingtheroomorisn’t,theimpressionisthesame—coldindifference.Youcan’ttellwhichitisdoingwithoutgoingandputtingyourhandonit.Theyburnlittlehandfulsofkindlingsinit,nosubstantialwood,andnocoal.

Ofcourse,the“polishedwhitetomb”isatilestove—akachelofen.MarkTwainobviouslyhadaverypooropinionoftheconceptashewrotethisessay.ItisfascinatingthatTwainwasaquickstudy,however,andbythetimehewroteanessaytitled“NationalStupidities,”hehadlearnedhowmasonryheatersactuallyoperate,thoughhestillsoughtimprovements:

TaketheGermanstove,forinstance—thehugewhiteporcelainmonumentthattowerstowardtheceilinginthecorneroftheroom,solemn,unsympathetic,andsuggestiveofdeathandthegrave—wherecanyoufinditoutsideoftheGermancountries?IamsureIhaveneverseenitwhereGermanwasnotthelanguageoftheregion.Yetitisbylongoddsthebeststoveandthemostconvenientandeconomicalthathasyetbeeninvented.

MarkTwainbeginsbyalmostrepeatinghispunishingremarksfromayearearlier,butquicklyseguesintopraiseforthemasonryheater,whichseemstobefoundonlyintheGerman-speakingcountries.Thebest?Mostconvenient?Mosteconomical?Hecontinues,possiblyreferringtohimself—the“uninstructedstranger”ofnottoolongago:

Totheuninstructedstrangeritpromisesnothing;buthewillsoonfindthatitisamasterlyperformer,forallthat.Ithasalittlebitofadoorwhichyoucouldn’tgetyourheadinto;adoorwhichseemsfoolishlyoutofproportiontotherestoftheedifice;yetthedoorisright,foritisnotnecessarythatbulkyfuelshallenterit.Small-sizedfuelisused,andmarvelouslylittleofthat.Thedooropensintoatinycavernwhichwouldnotholdmorefuelthanababycouldfetchinitsarms.The

processoffiringisquickandsimple.Hehashitonperhapsthebiggeststumblingblockforthoseaccustomedtothe

gapingmouthofanopenfireplace:asmalldoor.Thedoorissmall,ofcourse,becausethefirechamberissmall.Thefirechamberissmallbecausehardlyanywoodisused.Becausehardlyanywoodisused,buttheheaterisalwayswarm,itisveryeasytofire.Andtheresultofsuchlittlelabor?ThisiswhatTwainsays:

Alldaylonganduntilpastmidnightallpartsoftheroomwillbedelightfullywarmandcomfortable,andtherewillbenoheadachesandnosenseofclosenessoroppression.InanAmericanroom,whetherheatedbysteam,hotwater,oropenfires,theneighborhoodoftheregisterorthefireplaceiswarmest;theheatisnotequallydiffusedthroughtheroom;butinaGermanroomoneisascomfortableinonepartofitasinanother.Nothingisgainedorlostbybeingnearthestove.Itssurfaceisnothot;youcanputyourhandonitanywhereandnotgetburnt.Considerthesethings.Onefiringisenoughfortheday;thecostisnexttonothing;theheatproducedisthesameallday,insteadoftoohotandtoocoldbyturns;onemayabsorbhimselfinhisbusinessinpeace;hedoesnotneedtofeelanyanxietiesorsolicitudesabouthisfire;hiswholedayisarealizeddreamofbodilycomfort.[emphasisadded]

HereMarkTwainhasbecometheultimatemasonryheatersalesman.Whocouldpossiblypassbyaheatingmethodthatmakeshisentiredaya“realizeddreamofbodilycomfort?”Thecostoffiringtheheateris“nexttonothing,”andtheroomisequallycomfortablethroughout.Theunstintingpraisehebestowsonthekachelofenistemperedabitwhenhecomplainsthatthedoorissolidandonecannotseethefire,butherecognizesthemagicthatresultsfromitsinternaldesign:“Thisnoblestoveisatitsverybestwhenitsfronthasabigsquareopeninginitforavisiblewoodfire.Therealheatingisdoneinthehiddenregionsofthegreatstructure,ofcourse—theopen[visible]fireismerelytorejoiceyoureyeandgladdenyourheart.”Incredulousthatthisissomethingmomentousthatisbeingignoredontheothersideoftheworld,Mr.TwainconsidersthefollyofAmericanstubbornnessatnottryingthisadvancedheatingoption:

Americacouldadoptthisstove,butdoesAmericadoit?No,shesticksplacidlytoherownfearfulandwonderfulinventionsinthestoveline.

Shehasfiftykinds,andnotarationaloneinthelot.TheAmericanwoodstove,ofwhatsoeverbreed,isaterror.Therecanbenotranquilityofmindwhereitis.Itrequiresmoreattentionthanababy.Ithastobefedeverylittlewhile,ithastobewatchedallthetime;andforallrewardyouareroastedhalfyourtimeandfrozentheotherhalf.Itwarmsnopartoftheroombutitsownpart;itbreedsheadachesandsuffocation,andmakesone’sskinfeeldryandfeverish;andwhenyourwoodbillcomesinyouthinkyouhavebeensupportingavolcano...

Itiscertainlystrangethatusefulcustomsanddevicesdonotspreadfromcountrytocountrywithmorefacilityandpromptnessthantheydo.YoustepacrosstheGermanborderalmostanywhere,andsuddenlytheGermanstovehasdisappeared.5

THEWORLDOFTOMORROW

BettyandLarryColemanrentedahomeinNorwalk,Connecticut,from1973to1974.Larryhadtakenatemporaryteachingjobinthearea,andtheyhadarrivedwithababyintow.Theymovedintoahomethatwas,atthetime,ownedbythesonoftheoriginalhomeowners.Thoseoriginalownershad,inthe1940s,addedacoupleofroomsandanunusual-lookingtilestructure,nearlysquareinfootprint;itwasperhaps4to5feetwideand5to6feetdeep.Itstoodabout6feettall.Threeofitssideshadblue,attractivetile.About3feetupthesidesoftheheatertherewasattachedamasonryplatform—largeenoughandstrongenoughtoserveasabedforagrownman.Thefourthsidewasseeminglyattachedtoorwentthroughthewallseparatingthedining/familyroomfromthekitchen.Inthekitchen,theyfoundasmallfireboxdooropeningintothestrangeconstruction.Theoriginalownershadattendedthe1939World’sFairinNew

YorkCity.Thethemeofthefairwas“TheWorldofTomorrow.”Promotersofthiseventhadimagineditasacelebrationof“Man’sachievementsonashrinkingglobeinanexpandinguniverse.”Theretheyhadseenamagnificent,new(totheUnitedStates?)kindofwood-firedheateranddecidedthattheywouldputoneintheroomadditiontheywereplanningfortheirhome.Theycommissionedtheconstructionofoneintheirhome.The

Colemans’landlordcouldnotsaywhobuiltthestoveorexactlywhen,thoughhewascertainitwasinthe1940s.TheConnecticuthome’stileheater,remembersMr.Coleman,

hadthetiniestfireboxandaverysmalldoor.“Youcouldn’tputmorethantwoorthreelogsinthethingatonce,”hesaystoday.Herememberswell,however,thatthissmallamountoffuelalwaysproducedan“amazingamountofheat”fromthetile-facedstructure,whichwaspresumablyaboutthirtyyearsoldwhenhefireditin1973.ThoughbothLarryandBettyhaveheldthefondmemoryofthemasonryheaterforthepastthirty-fiveyears,theybelievetheyhavenotownedahousesincethattheyfeltdeservedorcouldproperlybeheatedbysuchafinething.

Today’smasonryheaters,asdemonstratedbythephotosinthisbook,arecertainlyfarfromlookinglike“solemn,unsympathetictombs.”Moreoftenthannot,theydohaveglassdoorsforfireviewingto“rejoiceyoureyeandgladdenyourheart.”Inotherwords,themodernmasonryheaterwouldsplendidlyfulfillthewishesofamanlikeMarkTwain.Fewwhorunacrosstheminmoderntimescancomeupwithanyreasonwhymasonryheatersarenotthequintessentialwood-burningdevice.ThereisnodoubtthatAmericansareexposedtomasonryheaters.Somesee

themontelevisionorthemovies,buthavenoideawhattheyare.Thousandshaveseentheminmuseums,artshows,orantiquesstores.ComparedwithEuropeancitizens,relativelyfewhaveactuallylivedwithandfullyexperiencedmasonryheaters,butmasonryheatershaveexistedintheUnitedStatesandCanadaprobablyaslongasimmigrantshavecomefromEurope.Ithasonlybeeninthelastfortyyears,however,thatanymeaningfulmarketformasonryheatershasbeennurturedinNorthAmerica.

MasonryHeatersinNorthAmericaThedevelopmentofamasonryheatertraditioninNorthAmericaisashorthistory,butitinvolvesmanypeople.Thistextdoesnotclaimtobeacompletehistory,andthissectionismerelyabriefoutlineofhowsomelargeideasgrewfromafewsmallseeds.TherearescoresofunnamedartisanswhohavetirelesslyworkedintheirrespectivepartsofNorthAmericatocreatethe

conditionsforamasonryheaterrenaissance.Somedaytheirstorieswillalsobetold.Ourstorybeginsinthe1970sandearly1980sduringtheresurgenceoftheuse

ofwoodheatduringthe“energycrisis.”TheMiddleEastoilembargoledtoshortagesandgaslinesintheUnitedStates.Ininflation-adjusteddollars,gasolinein1981reachedahighofover$3pergallon.Heatingoil,ofcourse,followedsuit.Multitudeslookedforalternativesolutions,includingsolarenergyandareturntowoodforfuel.Though,aswe’veseen,mostofhumanhistorywaspoweredbywood,thatfuelwasreplacedslowlybyfossilfuelsinthetwentiethcentury.Whenfossilfuelpricesskyrocketed,woodbecamethecheapalternativethatofferedenergyindependencetomillions.Intheearly1980stheback-to-the-land,energy,andself-sufficiencymagazine

MotherEarthNewsembarkedonaprojecttobuildwhatitcalled“MyMother’sHouse.”Solarenergyandearth-shelteringtechnologieswouldbeusedtoproduceavery-low-energyhousebuiltwithtechniquesofrelativelylowcost.Inpart7ofthemulti-installmentmagazineproject,thestaffintheNorthCarolina“eco-village”describedtheconstructionofa“so-calledRussianfireplace.”Theirmasonryheaterwasasingle-skin,five-fluedesignbyBasilio

Lepuschenko,acarpenterfromMaineandimmigrantfromBelarus.Inthemid-1970shehadbuiltamasonryheaterforhisfather-in-lawusinghismemoriesfromtheoldcountryashisblueprint.Thestoveshedesignedwerenarrowbutlongandtall,usuallywitheitherthreeorfiveverticalfluesabovethelong,lowfirebox.Mr.Lepuschenko,nowdeceased,wasoneofamerehandfulofindividualspromotingmasonryheatersintheUnitedStatesduringthelate1970swood-energyresurgence.BasilioLepuschenkohadsomeinfluenceonseveralkeyindividualsacrossNorthAmerica.

FIGURE2.13.Abrick,single-skin(meaningtheinnerlifeandveneerareone-and-the-same,seechapter8)heaterbuiltusingBasilioLepuschenko’splans.Thedoors,frombottomup,areashcleanout,fuel-loadingdoor,andsootdoor.Theheaterwassubsequentlystuccoedwhite.PhotobyDeanWitt.

LepuschenkoevenhadabriefbusinessrelationshipwithAlbieBardeninNorridgewock,Maine.Bardenwasanon-masonwhofeltthehandofProvidenceonhisshoulder,urginghimtolearnabout,teach,andbuildmasonryheatersafterreadingabouttheminNewLow-CostSourcesofEnergyfortheHome.6Albiewasalreadysellingwoodstovesfromhishomebusiness,theMaineWoodHeatCompany.Whenhesawamasonryheaterinthatbookheknewhehadfoundhislife’sworkandsoughtoutalltheinformationhecould.ThisresearchledhimtobothBasilioandaFinnishcarpenter,SamJaakola,whohadbuiltseveralheaters.Withtheinformationhegathered,hebeganwritingarticlesaboutmasonryheatersandevenobtainedabookcontract.Thoughhedidn’tcompletethatcontract,heself-publishedaconstructionmanualyearslater.Ataboutthesametime,articlesaboutLepuschenko’sheaterswerespreadingacrossNorthAmerica,andBasiliowasdrawingupandsellingplansforhisdesigns.

THERIPPLESINTHEMASONRYHEATERPOND

IranheadlongintotheripplesofAlbieBarden’searly-1980seffortstopromotemasonryheatersin2005.LindaMurray,living

innorthernLowerMichigan,calledandreportedthatherFinnishfireplace,builtcirca1980,wasnotfunctioningcorrectlyafterbeingservicedbyalocalbrickmason.Ms.Murrayreportedthatherbrickheaterhadbeentheprimaryheatsourceforhermodesttimber-framehousesinceitwasconstructedtwenty-fiveyearsearlier.Shehadcalledthelocalmasonin2004becauseshenoticedthat

(afternearlytwenty-fiveyears)someofthefirebrickslookedliketheyweredeteriorating.Shereportedthat,mainly,therear,lowerfireboxwallbrickslookednoticeablyworn,andtherewasadditionalminordeteriorationonthelowersidewallsofthefireboxaswell.Consideringhowwelltheheaterhadperformedforsolongandhowmuchshedependedonit,shedecidedtohaveitservicedandbroughtbacktoascloseas“likenew”conditionaspossible.Unfortunately,themasonshefinallyhiredforthejob(after

gettingseveralestimates)admittedheknewnothingaboutFinnishfireplaces,butwascertainhecouldrestoretheheatertopristinecondition.Themethodhechosewastocompletelyremove,viathefireboxdoor,allthefirebrickinnardsoftheheater.Heproceededtofillalltheheat-exchangepathways(criticalfortheoperationoftheheater)withrubbleandmortar,andbuildaconventionalfireboxdesignedtosimplyventdirectlyintotheadjacentchimney.Whenhewas“finished,”themasonryheater’snewfireboxexhaustedstraightupfromthechamber,throughanarrowthroat,andexiteddirectlyintothechimneythroughthebypasschannel.AbypasschannelissometimesusedinFinnishheaterstoallowexhausttotemporarilybypasstheheat-exchangefluesoftheheater—oftentoaidininitialstart-upwhentheheateriscold.Inthismason’sredesign,thebypasswastheonlypaththeexhaustcouldtake.Needlesstosay,theheaternolongerfunctionedasaheater.

Murraywasatalossandexplainedthatshehadevenshownthelocalmasontheconstructionplansfortheheater—amanualwrittenbyAlbertBardenIII.Themasonsaidhedidn’tneedthem“becausehehadexperiencebuildinghundredsoffireplaces.”

Whenquizzed,shecouldnotrecallthenamesoftheoriginalbuildersofthemasonryheater,buttheyhaddoneasuperlativejobconstructingabasic,no-frills,red-brick-facedheaterthathadfunctionedjustasdesignedfortwoandahalfdecades.Inordertorestoretheheatertooriginalfunction,andtopreservethewell-executedbrickveneerthatshowednosignsofcrackingordeterioration,Ionlyrebuilttheinteriorcoreoftheheater.Ididthispartiallythroughthefireboxdooropening,andcompletedthebalancebyreachingdowninto(andevenclimbinginto)theheaterthroughtheremovableslabsatthetopoftheheater.Thelocalmasonendeduppayingtheresultingbill.Hepaidahighpricefornottakingsometimetounderstandwhatamasonryheaterisandhowitisbuilt.

BythetimeDavidLyle’sBookofMasonryStoveswaspublishedin1984,thoughLylecouldlistadozenorsoNorthAmericansourcesfortilestoves“ofonekindoranother,”BardenandLepuschenkoweresingledoutasthestartingpointsforan“increasingnumberofmasons...experimentingwithbrickstoves.”Barden’sfascinationwiththe“new”oldtechnologydrovehimoverseastolearnmore.HetraveledtoFinlandinearly1978.Asolidtraditionofmasonryheatersalreadyexistedthere.Bardensoughttolearnanddevelopprofessionalrelationshipswiththosewhocouldhelphimfulfillhiscalling.BackintheStatesinthespringof1978,BardenaskedLepuschenkototeach

twoworkshopsusingLepuschenko’sdesigns.TheworkshopswerewellattendedbymasonsfrombothMaineandthroughouttheUnitedStates.AlbieBarden’smasonryheaterworkshopcareerhadbegun.AfterreadingabookbyHeikkiHyytiainen,fromFinland,BardencalledtheauthorandinvitedhimselfandmasonDougWoodonasecondtriptoFinland;theywerehostedbyHyytiainen.Aworkingrelationshipblossomed,andHeikkiHyytiainenandAlbieBarden

eventuallycollaboratedonabook,publishedinFinlandin1988,titledFinnishFireplaces:HeartoftheHome.AsHeikkistatedinthebook,“AprofoundfriendshipandcooperationwasbegunwhichwasthebasisforthisbookandseveralinternationalworkshopsandbusinessarrangementsbetweenAmericanandFinnishheatergroupsandfirms.”7Indeed,inthoseearlydays,BardenhostedanumberofworkshopsunderHeikki’sdirectionthatpiquedtheinterestofmasonsalloverNorthAmerica.Liketheconcentricripplesfromastonedroppedinapond,themessageofmasonryheatersspreadthroughthecontinent.

NotlongafterBardenreturnedtoMainefromhisFinnishfireplaceodyssey,acustomercontactedamasonry-contractingfirmonVashonIslandinWashingtonState.PartnersTomStroud,BruceDietmeyer,andRichardWardwereaskedtobuildaRussianfireplace.Theirresponsewassomethingalongthelinesof,“What’saRussianfireplace?”Opentonewideas,however,theylookedovertheinstructionsforthefireplace—instructionsfromBasilioLepuschenko.(Later,theylearnedtheseplanswerebasicallyidenticaltoplansavailablefromtheUniversityofMoscow.)Aftercarefulconsideration,theypresentedanestimatetotheclient,whofoundthepricetoohighandrejectedit.Theseed,however,hadbeenplanted.Aroundabout1980,Dietmeyer,Ward,andStroudwereapproachedbya

GermancoupledesiringaGermantileheater—akachelofen.ThepartnerssoldthemontheRussiandesign,whichtheyproceededtobuild.Theteamhadproduceditsfirstmasonryheater.TomStroudandhiscohortsatthetimewerealsopartofanintentionalcommunitybeingbuiltonVashonIsland.TheWesleyanCommunitywasgearedtowardenvironmentallysoundconstruction,includingpassivesolarattributesandsustainablematerials.TheyquicklyrealizedthattheRussianfireplacewasaperfectcomplementtothecommunity’spurpose.Itwasn’tlongbeforetheyhadanotherhalfadozenormoreheaterstotheircredit.Meanwhile,inthedesertSouthwest,JayJarpe,aresearchengineer,was

workingwithagroupofindividualsledbyRobertProctor,aNewMexicoadobemason.Proctorhadreceivedastategranttobuildeightgrubkasinvarioussouthwestcommunities.AgrubkaisyetanothertypeofRussianfireplace.ItdifferedfromLepuschenko’sdesigninthatithaditsfireboxdoorononeofthelongfacesoftherectangularheater,ratherthanononeofthenarrowends.Proctor’sambitiousprojectwassponsoredbytheUniversityofNewMexico,

andfundedthroughtheNewMexicoEnergyInstitute.Eachoftheeightmasonryheatersbuiltwasuniqueandinstalledatadifferentelevation.Alleightheaterswerealsofittedwiththermocouplestomonitorthermalperformanceandtodeterminehowheattraveledthroughthem.Thermocouplesaresimplytemperaturesensors.Suchasensorcanbeinsertedanywhereinsidethemasonryheaterwithwiresleadingtotheoutsideoftheheaterbeingattachedtoamonitorforreadingtheinformationsensedbythethermocouple.TheconstructionoftheseheaterswascarefullydocumentedbyMr.Jarpe,whothenpublishedamanualinMay1981titled,“RussianFireplace:Demonstrationsand

Workshops.”8

Dietmeyer,Ward,andStroudwereinfluencedbythedesignsthatcameoutofProctor’sprojects.Theylikedthegreaterversatilityofthedoorlocationonthelongsideoftheheaterandbegandoingtheirownexperimentswithdesign.TomStroudbeganteachingstanding-roomonlyseminarsinlocallibraries—twentytothirtyinayear.Thepublicwasenthusiastic,andDietmeyer,Ward,andStroudknewsomethingspecialwashappening.Nottoofaraway,JerryFrisch,anotherWashingtonStatemason,waslikewiserunningseminarsandbuildingheaters,asclientshadbegunapproachinghimtobuild“Russianheaters.”Havingbeenbornintoaunion-masonfamily,Mr.Frischquicklygraspedtheconceptandranwithit.HewouldlatershowakeeninterestinSwedish-stylekakelugnsaswellastheFinnishandRussiandesigns.

FIGURE2.14.TheEnvirotechRadiantFireplacebecameverypopularintheNorthwestafteritsintroductionbyDietmeyer,Ward,andStroud,Inc.Thisbrickheateriswellplacedbetweenakitchenandlivingroom.PhotocourtesyofEnvirotechMasonryHeaters.

Withtheseedsofamasonryheatercultureplantedinthesouthwestern,northwestern,andnortheasternpartsoftheUnitedStates,thebirthofanentirenewindustrywasimminent.IntheEast,Bardenwasbusilyteachingworkshops,predominantlyaboutFinnishfireplaces,inthemid-1980s.Hehadaddedcookers(cookstove/ovens)tohisrepertoire.Helikewisewasinstrumentalinbringinga

largesoapstonemasonryheatercompany,Tulikivi,intotheUnitedStates.Hehadalsobecomeanimporterofqualitycast-irondoorsandotherheaterhardwarefromFinland.IntheNorthwest,TomStroudandhispartnersgottheattentionofafifth-

generationkachelofenbuildernamedErnstHeuft.Besidesbeingbornintoafamilyofheaterbuilders,HeuftwenttokachelofenschoolinStuttgartasayoungman.Reluctantatfirst,heeventuallyworkedwithandtrainedtheteamforseveralyears.Theybeganbuildingheatersofeveryshapeandsize,includingtwo-storybehemoths.Theybuiltovens,bothdomesticandcommercial,andmasonrycookstoves.Theireffortsculminatedintheircreatingamanufacturedheater-corekit,theEnvirotechRadiantFireplace(seechapter8),andalongrunofheaterbuildingthatStroudestimatesresultedinapproximatelyonethousandheatersbeingbuiltbyDietmeyer,Ward,andStroudbetweenroughly1980and2000.By1990Barden,ontheEastCoast,hadspokentodozensofmasonsat

variousworkshops,andthisveritablearmyoffledglingheatermasonswasbusyspreadingtheheatergospelintheirrespectivestatesandmunicipalities.In1988,masonryheatersreceivedexemptstatusfromtheUSEnvironmental

ProtectionAgency(EPA).TheEPArecognizedthatmasonryheatersareinherentlycleanburningbecausetheyburnwoodinaconfinedfireboxwithplentyofoxygenandthushavehighcombustionefficiency.Inaddition,theyrecognizedthatitwasnotpossibletoplacemasonryheaters,whichweighsignificantlymorethanthemaximum1,764pounds,onthetypicalscaleslaboratoriesusetoconductwoodstoveburnrateandemissionstests.By1992,masonryheaterproponents,aspartofanewASTMInternational

taskgroup,hadsecuredanewASTMspecification,E-1602.Thisnewspecificationofficiallydefinedmasonryheatersanddescribedtheirattributesinawaythatcouldbeunderstoodandacceptedbybuilding-codeofficialsaroundthenation.WithEPArecognitionas“exempt”and“clean,”andwithatooltosatisfybuildingdepartments,thedoorstomasonryheaterbuildingwerewideopenbythemid-1990s.Sincethen,thousandsofmasonryheatershavebeenbuiltinNorthAmerica,andheatermasonsaregrowinginbothknowledgeandnumberwhereverheatforhomesisrequired.

TheFireplaceoftheFuture?

Asthisbookgoestopress,theEPAisagainreviewingandupdatingitsNewSourceProductStandards(NSPS).Thistime,itappearsthatmasonryheaterswillnotbesetasideassimply“exempt.”TheEPAhasbeenchargedtoregulateanyappliancethatburnswood,andmasonryheatersarealsointheirsights.However,masonryheatershaveafirmhistoryofhighefficienciesandtestedcleanlinessbothinNorthAmericaandaroundtheworld.Itmaybethatmasonryheaterswillsetthestandardforallotherwood-burningdevices.Whatevermayhappen,itcannowbesaidthatthereis,indeed,amasonry

heatertraditioninNorthAmerica.Eachyearmoreandmoreheatersarebuilt.Eachyearmoreandmoremasonslearnthetrade.Thosedeeplyinvolvedinthebusinessofmasonryheaters—especiallythosewhohavebeenaroundthemsinceBasilioLepuschenkofirstbuiltaheaterforhisfather-in-lawbackinthe1970s—canseethevolumeofinterestnearingthepointatwhichitmayresultinexponentialgrowth.Whencriticalmasshits,itmaybeseeninshortorderhowAmericaningenuitycanpropelaverygoodthingtohistoricalgreatness.AtonetimeinAmerica,eachloafofbreadmadewasassembled,kneaded,andbakedbythehandsofindividualbakers.Nowa“bakery”isamanufacturingfacilityturningoutthousandsofloavesinaday.Thishasmadebreadinexpensiveandabundant.Thesameresourcefulnesscouldmakehigh-efficiencymasonryheatersabundantandinexpensiveinAmerica.Whilemasonryheatersnowareoftenbuiltbyindividualartisans,thefuturemayfindsomethingdifferenthappening.Thetimetofindoutisfastapproaching.

FIGURE3.1.Thisunusualredsandstonemasonryheaterwasdesignedonthefly,piecebypiece.Itincorporates5-inch-thicksandstoneslabsfortheraisedhearth—allcutfromthesamehugeslabofstone.Someofthe“scrap”fromthat(somescrapsmeasured2or3feetsquare)formedtheupperveneeroftheheaterbelowthelevelofthebakeoven.Otherviewsofthisheatercanbeseeninfigures6.31,6.36,and6.43.HeaterbyMarenCookeandKenMatesz;photobyMarenCooke.

CHAPTERTHREE

ThermalComfort:TheVerticalRadiantAdvantage

MostpeopleintheUnitedStateshaveneverlivedinahousethatisheated.Thismayseemaludicrousclaim,butit’sneverthelesstrue.Manyareusedtosaying,“Iheatmyhousewithagasfurnace,”or“Igrewupinahouseheatedwiththoseold-fashionedradiators.”Whensomeonesaystheyliveinahouseheatedwithaforced-airfurnacebuttheywanttoheattheirhomeorroomadditionwithamasonryheater,thetruthisthatatlasttheywillexperienceahomethatisactuallyheated.Masonryheatersareuniqueheatingsystems.Amasonryheateris,infact,one

oftheonlywaysofheatingthatactually“heatsahouse.”Manywillfindthisstatementalittleconfusing;theyaresurethattheyhavealwayslivedinawarmhouse.Mostheatingsystemsdonotheathouses.Instead,theyprovidetheoccupantswithsomemeasureofthermalcomfort.Thermalcomfortcanbeachievedindependentlyfromhousesandheatingsystems,soitwillbehelpfultosayabitmoreaboutit.

ThermalComfortThosewhoworkintheheatingorair-conditioningfieldsmustaddressthermalcomfortineveryseason.Thermalcomfortinthesummerwillrelatetohowcomfortablepeoplefeelinthemidstofwarmorevenhotandhumidweatherconditions.Technicallyspeaking,thistopicrelatestohowpeoplefeelinallenvironments,whetherinsideoroutdoors,inhotsummerorfrigidwinter.Thermalcomfortforpurposesofthisbookreferstowhetherornotpeoplefeelcomfortable—maybeevenwarm—inanenvironmentthat,withouttheuseofenergy,wouldbequitecoolorcold.Youdon’thavetobewarmtobecomfortable.Whatdoesitmeantofeelwarm?Whatdoesitmeantohavethermalcomfort?

Thesemayseemoddquestionsatfirst.Mostpeoplemightsaytheyknowwhentheyarewarmandwhentheyarecold;surelytheyknowwhentheyare

comfortable.Yetsomeexperiencecomfortdifferentlythanothers.Childrenoftenparadearoundoutsideinshortsandbarefeetondayswhenadultsfeelchilled.Warmthisrelativealso.Ifyou’vebeenoutsideonacold,snowyday,aroomat55°Fseemswarm;butifyousitinthatroomforawhilewithoutwearingacoat,you’lllikelybegintofeelchillyagain.Thischapterwillclarifywhatitmeanstobewarmratherthanjustcomfortable.

ThermodynamicsandMetabolismThermalcomfortcanbedefinedinascientificwaythattriestomeasuretheperceptionofwarmth.Amoreobjectiveexaminationofthermalcomfortinvolvesthephysicsandbiologyofheat.Onebranchofphysicsdealswiththermodynamics—thestudyofchangingenergyconditions,ofteninrelationtomatterinmotion.Consideringthatthehumanorganismisallmatterinmotion,thermodynamicsandhumanbiologyareintimatelyrelated.Thehumanbodyisaheatengine.Themetabolismisaheat-producing

machine,infact.ThewordmetabolismcomesfromtheGreekmetabol,meaning“change.”Livingbodiesareallabouttransformation.Foodiseatenandthebodyefficientlychangesthefuel,extractingtheenergyandnutrients.Thebodyusesthesebasicmaterialsandtheextractedenergytodowork,likebuildingorrepairingcellsandproducingtheheatitneedstosurvive.Theabilitytodophysicalworkcomesfromthatsamemetabolism.Thehumanbodyactuallyproducesexcessheatintheprocess.Thatheatis

dissipatedintotheenvironmentthroughevaporation,convection,andradiation.Inroundnumbers,about25percentoftheexcessheatislostthroughtheevaporationofmoisturefromtheskin.Convectionaccountsfor15to25percentoftheheatloss.(Convectionheatlossoccursthroughexhalationandtheactionofairmovementagainsttheskin.)Radiation—theemissionofinfraredradiantheatfromallbodysurfaces—thenaccountsfortheremaining50to60percent.Thebodyisalwayslosingitsexcessheatinalloftheseways.

FIGURE3.2.Auniquesourceofthermalcomfort:Averticalheaterforverticalpeople.Thiscustomsoapstoneheaterconsistsoftwoprimaryelements.Thefireboxiscontainedintheshorterpart;thetallerpartcontainsmostoftheflues.Theround“disks”areashcleanoutcovers,revealingcluesastowherevariousfluesarelocated.Everyflueneedsawaytobeaccessedforeventualcleaning.PhotocourtesyofNewEnglandHearthandSoapstone.

Thekeytothermalcomfortistiedtothisnaturalheatdissipation,togetherwiththesecondlawofthermodynamics,whichsaysthatheatalwaysmovesfromwarmerareastocolder.Thislawalsosaysthatheatnevertravelstheotherway—fromcoldertowarmer—withoutanexpenditureofenergy.ThuswhenIsetmyhotcoffeeonthetablenexttome,italwaysgetscoolerandneverwarmer.Itsheatdissipatesintotheroomairandthetablebelowit.Mostofthatheatislosttothesurroundingair,whichrisesintemperaturebyanimperceptibleamountbecauseoftheheatfromthecoffee.Someoftheheatistransferredtothetablebelow,andIcanfeelitifImovemycupforamoment.(Someonemightarguethaticewatersetonthetabletransferscoldtothetable—whichcanbefeltwhentheglassismoved—inapparentviolationofthislaw.Thetruthisthatheatisrapidlymovingfromthetabletotheicewaterandtherebygreatlyreducingthetabletemperature.)

FIGURE3.3.Thisheaterfeaturescutstoneinanashlarpattern.Oneofthetwocolumnsrisingallthewaytotheceilingcontainsthechimneyflue.Theothercouldcontainafluefromanotherapplianceorcouldjustbalancetheappearance.Noticehowthevigorousfirefillsthewholefirebox.PhotocourtesyofTemp-CastEnviroheat.

IfIsetmyfresh,hotcoffeeinanoventhat’s150°F,itwillstayhotlonger.Itwillstillcoolbecausethecoffeestartedatover200°.Thesecondlawdictatesthatithastocool(toreleaseitsheattotheslightlycoolersurroundings).Thewarmersurroundingairslowstheheatloss.IfIputthecoffeeintheovenat,say,205°,thecoffeewouldstayunchangedintemperature.Heatlossfromthecoffeeisnowzero.Whileminimizingheatlossfromcoffeesoundsterrific,humanswon’tdovery

welliftheirexcessheatlossisstopped.Asheatengines,peopleneedtobeabletoreleaseexcessheat.Thenormalcoretemperatureofahumanisabout98.6°F.Thenormalskintemperatureis83°to92°.Iftheambientairisalso98.6°(andthereisnowindforevaporativecooling),thesecondlawofthermodynamicsdemandsthatheattravelfromthesurroundings,whicharehotter,totheskin.Undertheseconditions(zeroheatloss),apersonatrestwouldcontinuegettingwarmerandwarmerbyabout1.8°perhourratherthanfeelingcomfortable.Anindividualsubjectedtothisheattransferwilleventuallysufferfromheatstroke

andworse.Instead,itturnsoutthathumanbeingsusuallyfeelcomfortablewithan

ambienttemperaturearoundthe70°Fmark.Thermalcomfortismorelikelywhentemperaturesareclosetothatmark;yetnosingletemperatureisaguaranteeofthatcomfort.Inthefinalanalysis,feelingthermallycomfortableisallaboutheatlossfrom

thebody.Thermalcomfortisn’taboutbeingwarmatall.It’smoreaboutfeelingtoomuchheatlossorfeelingthatnotenoughheatisbeinglost.Inmostheatedlivingspacespeopleexperiencesomedegreeofthermalcomfort,buttheymayfeeleitherhotorcold.It’spossibletogointoahomewithanindoortemperatureof72°Fandfeelcold.Likewise,it’spossibletobeinanenvironmentwithanaverageairtemperatureof65°Fandfeelhot.Toomuchheatlossresultsinfeelingcold;notenoughheatlossresultsinfeelinghot.LikeGoldilocks’sporridge,thebalancehastobejustright.

ThermoregulationFortunately,thehumanbodyalsohasanincrediblecapacityforadjustingtoitsenvironment.Thiscapacityiscalledthermoregulation.Ifyoufeelcoldinahouseheatedto72°F,itisoftenbecausetheairaroundthehouseismoving.Theforced-airfurnaceblowsair,makingthecurtainsdanceandyourgoosebumpsgrow.Youcanfeeltheairmoveagainstyourhandsandcheeks.Meteorologiststalkaboutthisphenomenonofteninthewinter:It’sthewindchillfactor.Movingairatagiventemperaturefeelscolderthanstationaryairatthattemperature.Airmovingagainsttheskindramaticallyincreases(convective)heatloss.Theincreasedheatlosstriggersthethermoregulatorysystemtoconstrictbloodvesselsintheskin,reducingbloodflowtotheskin.Blood,oneoftheprimarycarriersofheatthroughthebody,can’ttravelasreadilythroughconstrictedbloodvessels.Thebodyisthusconservingheat—whichitneedstodotostayalive.Inturn,thereducedbloodflow,particularlyinthehandsandfeet,resultsinthefeelingofbeingcold.Indeed,thesurfacetemperatureoftheskinundertheseconditionscangetquitelow(55°to65°),eveninsideanotherwise“warm”house.Similarly,youcansitnearalargewindowina“warm”houseandfeelcold—

feeltoomuchheatloss.Oftenthesurfacetemperatureofawindowissubstantiallylowerthantheothersurfacetemperaturesandindoorair

temperature.Ifyouobservecarefully,youcanalmostfeelheatbeingsuckedfromyourbodytowardacoldsurface.Inthiscase,youloseaninordinateamountofradiantheattothewindow.Liketheicewateronthetable,thecoldwindowdrawsheatfromallthewarmerobjectsnearby.Again,theskincoolstooquicklyandthebloodvesselsconstrict.Onceagainyoufeelcoldasyourbodyactstopreventexcessheatloss.Anadditionalfactorinfeelingtoomuchornotenoughheatlossisrelative

humidity.Evaporationofmoisturefromtheskinisanotherwaythebodydissipatesitsheat.Inafashionsimilartoconvectiveheatexchange,theenvironmentwillalwaysseekmoistureequilibrium.Thelawsofphysicswillnotallowsomethingmildlydamptoexistagainstsomethingverydry.Moistskinwillquicklylosemoistureindryair.Inaroomwithlowhumidityof20percent,evaporativeheatlossfrompeopleismuchgreaterthaninaroomwitharelativehumidityof40percent.This,infact,ismuchofwhatisexperiencedwithsummertimeair-conditioning.Anairconditionergreatlyreducestheindoorhumidity,andtheincreasedevaporativeheatlossfromthebodymakesyoufeelcooler.Inthewinter,whenthebodycraveswarmth,however,losingmoisturetoofasttriggersthebody’sheatconservationmeasuresagain.Thermoregulationclosestheporesoftheskin,constrictsbloodvessels,andreducesbloodflow.Thebody’sabilitytoadjusttothesecircumstancesisincredible,butnot

complete.Thisis,afterall,whyaprotectiveindoorenvironmentisneeded—tocompensateforthebody’sthermoregulationlimits.The“justright”conditionsactuallyfitintoarelativelynarrowrange,beyondwhichthebodystrugglestocompensate.Itisthatbiologicalstruggleagainstexcessheatlossthatpeoplearenoticingwhentheysaytheyfeelcold.Inasettingwhereheatlossis“justright,”nostruggleemerges.InthewordsofJohnSieganthaler,inhisbookletRadiantArchitecture,“Thermalcomfortisachievedwhenwearetotallyunawareofhoworwhereourbodiesarelosingheat.”1

Withanunderstandingofwhatitmeanstohavethermalcomfort,it’spossibletobegintoseewhysomepeopleclaimtohavewarmhouses,butstillmaynothavethermalcomfort.Thermalcomfort—feelingwarm—isnotjustamatterofsettingathermostattoacertaintemperature.Inthesamewaythatexperiencinglifemeansmorethanjustinhalingandexhaling,feelingwarmmeansmorethanjustlivinginahousekeptatacertaintemperature.

WhatHeatstheHouse?

Ihaveneverheardsomeoneask,“HowcanImakesuremyfamilyneversuffersexcessheatlossfromtheirbodies?”Yettheprevioussectionshowedthatthisreallyisthequestionthatneedstobeaskedifwewantthermalcomfort.“Heatingahouse,”aswenormallyunderstandit,isnotreallyaboutheatingahouseatall;it’saboutthermalcomfortforthepeopleinsidethehouse.Narrowingthefocustodeterminehowtoachievethermalcomfortrequiresunderstandingwhatheatingoptionsthereareanddiscoveringhowthoseoptionsapproachthegoalofthermalcomfort.Whatmethodofheatingisbeingused?Doesitprovidethermalcomfort?Ifnot,whynot?Ingeneral,mostpeoplehaveaheatingsystemthatreducesmostexcessheat

lossfrommostoccupants.Ingeneral,designersofheatingsystemsexpectthatifaheatingsystemprovidesadegreeofcomfortto85percentofthepeoplewhoexperienceit,itisadequate.Thereissomethingamisswhenitbecomesacceptablethat15percentofthepeopleinahousemaybeuncomfortable.Wouldanyonewant15percentoftheirhousemateshungry?Ill?Unhappy?Ifnot,whywouldanyonebecontentwith15percentofthepeopleintheirhomesbeingunabletohavethermalcomfort?Anotherwayofsayingthisisthatinafamilyofseven,it’sacceptableforone

ofthemtobeuncomfortable.That’sreallyunfortunatefortheseventhindividual.Oftenit’sanolderpersonwhosethermoregulatorysystemisnotquitewhatitoncewas.Everyoneisdifferent,though,andsometimesit’saveryhealthy,robustindividualwhosimplydoesn’thaveagoodexperienceinaclimatethatothersfindadequate.Sometimesit’snotthemembersofthehouseholdatall.Insteadit’saguestwhoprodshiswifetotakehimhomeearlybecausehecan’tfeelcomfortableinthehousehevisits.Anotherversionofthissameissueiswhenoneortwopeopleare

uncomfortablywarmwhentheothersarehappy.Thisistheclassicdilemmainwhichperhapsthewifeisadjustingthethermostathigheronlytohavethehusband,feelingtoowarm,adjustingitlower.Neitherisquitecomfortableintheclimatetheotherprefers,andsothebattlegoesondayafterday.Thesearethedilemmasfacedbyallthoseseekingthat“justright”

environment.Yetsomehowthisdilemmaisoftencompletelyignoredwhenselectingawayof“feelingwarm”inaneworremodeledhouse.Moreoftenthannot,peopleacceptthiseither–orsituationastheonlyreality,andchoosenottoaddresstherealproblemofhowtocreatethermalcomfortforeveryoneinthehome.Intheend,mostpeoplestillchooseoneofthemostcommonwaysof

combatingexcessheatloss,whateveritsshortcomings.

FIGURE3.4.Thisstucco-and-tilemasonryheaterincorporateswoodforthebenchsurfaces.Cornersaregentlyrounded,givingtheotherwiserectilinearelementsasoftappearance.TheblackloadingdoorgivestheclassicEuropeanlookandhintsatasmallfirebox.Theshapeofthetilesisatraditionaloneaswell.Noticehowtheheater’sbenchstepsdowntothelefttofollowthelevelchangeintheroom.PhotocourtesyofBiofire,Inc.

ConvectionHeatConvectionheatingisbyfarthemostwidelyusedheatingsystemintheUnitedStatestoday.Anestimated80percentofhomesthroughoutthecountryusesome

formofconvectionheatingsystem.Aconvectionheatingdeviceworkspredominantlybyheatingairandcirculatingthatwarmairthroughoutthebuilding.Suchasystemusuallycomprisesafurnace,afan,andductwork.Thefurnaceheatstheair,andthefanblowsitthroughtheductworktoallpartsofthehouse.Thusitiscalledaforced-airheatingsystem.Suchanarrangementmayhaveafurnacethatuseselectricityorburnsnaturalgas,fueloil,propane,orwoodtoheattheair.

FIGURE3.5.Thisbrick-facedmasonryheaterhasamassiveheatedsittingareatotheleft.Theexhausttravelsthroughfluesinsidethebenchdirectlyafterleavingthefirebox.Thecurvedshapeofthebenchexpandsthewalkwayfromthestairsontheleft.Figures4.6and5.1showotherviewsofthisheater.

Someofthesesetupsareverysophisticatedandmayalsobepartofalargergeothermalsystemforbothheatingandcooling.Geothermalfurnacesmakeuseoftheearth’sstoredheattoreducetheenergyneededtoheatorcoolair.Geothermalheatingmethodsareoftenthoughtofasthemostenergy-efficientsystemsavailable.

Otherconvectionheatingarrangementsarelesscomplexorareslightvariationsonthefurnace/blower/ductstheme.Forexample,hot-waterradiatorsarealsoconvectionheaters.Hereaboilerheatswater,whichispumpedtoradiatorsintheroomsofthehouse.Thehotradiatorintheroomwarmsadjacentair,whichrisestowardtheceiling,pullingcoolerairbehinditthatisalsothenwarmedbytheradiator.Thisestablishesaconvectioncurrentofairconstantlycirculatingthroughtheroom.Thehottestairrisesandmovesacrosstheceilingwhilethecoolerairtravelsalongthefloortowardtheradiator.Similarly,electricbaseboardheatersuseelectricalresistancetoheatmetalelementsthatpowertheconvectioncurrent.Thecommonmetalwoodstoveisperhapsoneofthesimplestconvectionheaters.Likethehot-waterradiator,metalwoodstovesrelymainlyonveryhotsurfacetemperaturestoestablishconvectioncurrents.Allofthesesystems,inonewayoranother,mainlyheatair.

TYPESOFHEATTRANSFER

Convection:Aconvectionheatingdeviceworkspredominantlytoheatair.Abaseboardelectricheater,forexample,hasaverysmallsurfaceareabutachievesquitehightemperaturesonitssurface.Thesehightemperaturesencourageconvectionascoolairapproachesthehotelements,getswarmedbythatheat,thenrisestowardtheceiling.Thismovingairpullsbehindityetmorecoolairthatalsoiswarmedbytheheater.Acyclehasthusbegunthatsendswarmairupandacrosstheroomorlivingareaascoolaircontinuestobepulledbehindthebuoyantrisingmass.Conduction:Aconductionheatingdeviceworkstowarm

somethingbydirectcontact.Forexample,acoldteakettleplacedonahotelectricburnerofastovetopwillbewarmedbythatdirectcontact.Conductionisnotapracticalspace-heatingmethodbecauseitrequiresconstantdirectcontactwiththeheatsource.Radiation:Aradiantheattransferinvolvesthemovementof

heatenergyacrossspaceanddoesnotrequireairorcontactwithobjectsforthetransfertooccur.Infraredelectromagneticradiationisthemorescientifictermforradiantheat.Themostfamiliarexampleissunshinestreamingthroughthewindowofahome.Someonesteppingintothepathofthesunshineimmediatelyfeelswarmthfromit.

Inahousefilledwithwarmair,thehouseandpeoplearenotheatedbythatwarmair.Thisisimportanttorealizebecauseitrevealsthetruenatureofconvectionheatingmethods.Thickquilts,sweaters,hats,gloves,spunfiberglass,walls,andwarmairarealljustblankets.Theyallserveasinsulationtokeepyourbodyheatfromescapingtooquicklytothecoldoutdoors.Theydonotwarmthebody;theysimplykeepthebodyfromlosingheattooquickly.Sinceeverybodyisdifferent,noteverybodywillbecomfortablewiththesamelevelofinsulation.Thisisthecruxoftheproblemwithconvectionheating.Itproposestoinsulateeverypersonthesamewayandmerelyhopesthatthiswillbesufficient.Asstatedbefore,however,thisdoesn’tworkfor15percentofoccupants.Forthosewhoarethermallycomfortableinanenvironmentheatedthisway,

itisvitalthatthewarmairbemaintainedalwaysatthesametemperatureorveryclosetoit.Iftheairtemperaturedropsjustafewdegrees,it’sthesameastakingalayerofclothesoffwhileoutside.Bodyheatdissipatesmorequickly,anditdoesn’ttakelongtofeelcold.ThetruthisthatmillionsofpeopleincoldregionsofAmericaburncopiousamountsofnonrenewablefuelstomaintainahigh-techblanketofairaroundthemselves,andmanyofthemstillaren’tcomfortable.

RadiantHeatLesscommonbutgaininginpopularityareformsofradiantheating.Manypeopletodayequateradiantheatwithin-floorheat.Masonryheaterscertainlyaresourcesofradiantheat.Whiletheconvectiveheatingmethodsdescribedabovestrivetodoanefficientjobofheatingair,radiantsystemsmakelittleattempttodoso.Infact,radiantheatistheonlykindofheatenergythatcantravelthroughavacuum.Allradiantsystemsfunctioninasimilarfashionforheating.Generally,somemeansisusedtouniformlyheatmaterials,aswhenwarmwateriscirculatedthroughtubesinafloor.Thewarmedmaterialsthenbecomeasourceofradiantheat.Preferably,masonryorotherdensematerialsareemployedforthis.Radiantheatislessunderstoodthanconvectionheat.Mostlikelythisis

becausesofewpeopleactuallylivewitharadiantheatingsystemcomparedwiththenearmonopolyheldbyconvectionheatingsystems.Tellingmostpeoplethatthermalradiationisentirelydifferentfromheatingairisliketellingafishthatit’salsopossibleforotherbeingstoliveinairinsteadofwater.There’sno

experienceonwhichtobaseadiscussion,somostpeopleassumeradiantheatactsjustlikehotair.Radiantheatdoesn’tbehavelikehotair.Infact,radiantheatdoesnotneedairatalltodoitsjob.

FIGURE3.6.Frontviewoftheheatershowninfigures4.8and8.1.Thiskachelofenwasdesigned,built,andphotographedbyErnstKiesling,CanadianKachelofen.

Gettingbacktophysics,radiantheatisinfraredelectromagneticradiation.Thetypeofelectromagneticradiationwithwhichpeoplearemostfamiliarislight.Whenalightswitchisflipped,lightimmediatelytravelsat,well,thespeedoflightfromthelightbulbtoareasallovertheroom.Lightandallelectromagneticradiationtravelsat186,000milespersecond;anditwilltravelthatfastthroughoutaroomregardlessofthetemperatureoftheair.That’swhyacampfireissopleasantevenonacoldautumnnight.Infraredradiantheattravelsdirectlyfromthefiretopeopleevenwhentheairisfrigid.Radiantheatfrommasonryheatersandradiantfloorsisonlydifferentfromlightinthatitisnotvisible.Otherwise,ittootravelsatthespeedoflightwithouttheaidorneedofair.Theradiantheatwithwhichmostpeoplearefamiliaristhatfromthesun.Everyonehasfelttheradiantheatofthesunontheircheeks,shoulders,orarms.Despiteexplanationsofthenatureofradiantheat,invariablysomeoneasks,

“Yes,buttheheatstillrises,right?”No.Radiantheatdoesnotrise.Infact,heatdoesnotriseinanycase.Hotairdoesrisebecauseitislessdensethancoolerair.Itisalwayswarmairthatrisesandpoolsincathedralceilingsandgoesupchimneys—butradiantheatdoesnotrise.Thereisnowaytomakeradiantheat“rise”otherthanpointingtheradiatingobjectupward,justasawarmfloorradiatesheattowardtheceilingortheradiantheatfromsomeverticalobjectissomehowreflectedupward.Otherwise,infraredradiationtravelsasraysdirectlyfromawarmobjectuntil

itreachesanotherobjectthat,ifcooler,absorbstheradiantheat.Radiantheatis

absorbedbythingsofsomemass.Itisnotabsorbedbyair.Infact,everyobjectthatiswarmerthanthethingsarounditisaradiantheater.Thecolorofthingsalsoinfluenceswhether(orhowmuch)radiantheatisabsorbed.Darkobjectswillabsorbmoreradiantheatthanlighterones;andshinymetal,likealuminumfoil,reflectsradiantheatjustlikeamirrorreflectslight.Radiantheatisabsorbedbyanobjectifthetargetobjectiscooler.Thesecond

lawofthermodynamicsisunyielding.Somethingwarmerthanaradiantobjectwillnotabsorbheatfromthatobject.Justtheoppositewillhappen:Thewarmerobjectalwayslendsitsheattothecooler.Thispropertyofheatmakesradiantheaterssomewhatself-regulating.Justasthehotcoffeeina205°Fovenlosesnoheat,aradiantheaternaturallyslowsitsheating(conservesenergy)assurroundingobjectsgetwarmer.Likewise,asthesurroundingsgetcooler,theheatexchangefromtheradiantsourceisgreater.Thetemperaturedifferencebetweenobjectslargelycontrolshowquicklyheatisexchanged.Whenobjectsarevirtuallythesametemperature,nosignificantradiantgainoccursbyeitherobject.Anotherprincipleofradiantheatersisthatthedistancefromtheheatsource

affectstheintensityoftheheat.Thinkingoflightagain,whenautomobileheadlightsareseenfromagreatdistanceonapitch-darknight,theyareseenastwopinpricksoflight.Butwhentheautomobileisonly20feetaway,thewholeareainfrontofthecarisbrightlylit.Similarly,withinfraredradiantheat,theheatisfeltmoreintenselywhenyou’reclosertotheradiantheatsource,butmaynotbefeltatallfromasignificantdistance.WhenIputmyhandsclosearound,butnottouching,myhotcoffeecup,Ifeelitsradiantheat;however,IcannotsensethatheatwhenImovemyhandsacoupleoffeetaway,eventhoughtheradiantheatisstillcontactingmyhand.Thedistancehasreduceditsintensity.

FIGURE3.7.Thismassivesoapstoneheaterismeanttoresemblealargeboulder.Thewholeveneerconsistsoflargesplit-facedstonescarefullyshapedtoblendtogetherasifitwereonepiece.Amultisideddoormakesfireviewingpossiblefrommanyanglesinthelivingspace.PhotocourtesyofTulikiviCorporation.

FIGURE3.8.Thisuniquebrick-and-soapstoneheaterfeaturesaspaciousraisedhearth.Thebenchsurface,mantel,andshelvesareallmadeofsoapstone.Thebuilt-inwoodstorageandshelvesprovidebothvisualinterestandpracticalstorage.Anarcheddoorandmatchingarchoverthenichesareaneleganttouch.PhotocourtesyofNewEnglandHearthandSoapstone.

Infraredradiantheat,againlikelight,alsocasts“shadows.”Alightshiningonthefrontofasolidobjectcastsashadowbehindit.Similarly,anobjectfacingaradiantheatsourcecanhaveaheatlessshadowbehindit.Thusifsomeoneputsahandbetweenmineandthecoffeecup,Iwillnolongerfeeltheradiantheatfromthecup.Myhandisinthethermalshadowoftheinterveninghand.Whenplanningtoheatwitharadiantsource,designersandhomeownersneedtobeawarethateverythinginthehousecancastsuchaheatlessshadow.Walls,furniture,rugs,ceilings,andpeopleallhaveaneffectonhowwelltheradiantheatisfeltthroughoutahouse.Themosteffectivedesignforradiantheatprovidesthemaximumexposuretotheradiantsourceandcreatesthefewestshadows.

In-FloorHeating

In-floorheatingoftenhasflexible,verystrongtubingruninaserpentinepatternandembeddedinconcreteunderthefinishedfloorofaroom,area,orwholehouse.Sometimeseventheconcreteisomittedandthetubingissimplyplacedunderawoodortilefloordirectly.Apumpcirculateshotwaterfromaboilertothismazeoftubing.Inthiswayitisverysimilartothehot-waterconvectionheatingsystemmentionedabove.Thissamejobofheatingthefloorisalsosometimesdonewithelectricalresistance.Inthiscase,alengthofheat-generatingelectricalwireisembeddedinthefloor.

Proponentsofin-floorheatingprimarilyliketocalltheirsystems“radiantfloors.”In-floorheatdoesindeedemitradiantheat.(Remember,anyobjectwarmerthansurroundingobjectsisaradiantheater.)Therearesomeimportantreasonswhyaradiantfloorshouldnotbeconsideredaradiantheatingsystem,however.First,awarmfloorsimplyisn’twarmenoughtobefeltandappreciatedas

radiantheat.Mostradiantfloorsaremaintainedat80°to85°F.Humanskintemperatureaverages83°to92°.Peoplearesimplywarmerthanwarmfloors.Whilewritingthis,Ihappeneduponanadvertisementfor“radiant”floorsinahomemagazine.Ifounditfascinatingthattheadusedapictureoftwoadultslyingonthefloor.Now,I’veseenalotofkidslyingon,sittingon,andplayingonthefloor,butit’sunusualforadultstolieonthefloor.Ofcourse,thisadvertisementisrightonthemoney:Ifsomeonewithsuchafloorwantstotrulyenjoythebenefitsofthisheatonhiswholebody,thebestoptionistolieonthefloorbecausethefloorissimplynotwarmenoughtotrulyprovideradiantheattopeople.Second,awarmfloor,withitslargesurfacearea,willnecessarilyexposealot

ofairtoitswarmsurface,therebyheatingmoreviaconvection.AccordingtoJohnSieganthaler,“Atypical‘radiant’floorsystemgivesoff50%to70%ofitsheatasthermalradiation.”2Thequotesaround“radiant”arehis,apparentlyinacknowledgmentthatsuchafloorisonlymarginallyatrueradiantpanel.B.F.RaberandF.W.Hutchinson,intheirbookPanelHeatingandCoolingAnalysis,addressthisquestionspecifically:Whendiscussingthedefinitionofradiantpanels,theauthorsclearlystatethat“[This]definitionisveryloose,foritdoesnotdistinguishbetweenfloorheatingpanels,whichdissipatethegreaterpartoftheirenergybyconvection,”3andverticalpanelsthathaveagreaterproportionoftheirheatdissipationbyinfraredradiation.Next,evenifa“radiant”floorwerealotwarmer,itwouldstillnotbe

experiencedasawarmpresencelikethesun.Thehorizontalsurfaceofthefloorissendingmostofitsradiantheatvertically.(Infraredraysprimarily,thoughnotentirely,departanobjectperpendiculartotheradiatingsurface.)Thus,mostoftheradiantheatfromawarmfloorbypassesverticalobjectslikewallsandhumanbeings.Itisverylow-intensityradiantheatthatparallelsverticalthingsonitswaytotheceiling.Youcanimaginewhattheinfraredrays“see”ofpeopleandthingsstandingonthefloor.Ifthefloorweremadeofglassandsomeoneinthebasementlookedstraightupintotheroomabove,thatpersonwouldsee

mainlythesolesoffeetandjustasmallcrosssectionofhands,andmaybehipsandchins.Alsoseenwouldbetheundersidesoffurniture,which,althoughclosetothefloor,nevergetwarmenoughtobecomeradiatingbodiesthemselves.Anytimewarmfloorsarediscussed,wemustconsiderheatingbyconduction.

Conductionofheatdirectlytopeopleisamajorfactorwhenyouopttohaveheatedfloors.Tomany,thefeelofwarmfloorsonthefeetistheprimaryreasonforselecting“radiant”floors.Thedirectcontactwiththefloor,theconductedheat(whenthefeetareactuallycoolerthanthefloor),iswhatfeelsgood.Theseaspectsofwarmfloorsshowthatwarmfloorsreallyare,mainly,warm

floorsandnotradiantheatingdevices.Approximatelyhalfofsuchafloor’sheatenergyisusedtoheattheair,justlikeotherconvectionsystems.Theirprimarycomfortisachievedbyconductiontopeople’sfeet,whiletheremainingradiantaspectistooweaktoreallybenoticed.

FIGURE3.9.Auniquebrickandtile-facedheaterbuiltaccordingtothesystemoffreegasmovement(seechapter8).Theheaterincorporatesstorageand/orworkspaceabovethefireboxaswellasabuilt-inwood-storagearea.Ontheleftsideisthedoorfortheintegralbakingoven.Seetheothersideofthisbeautifulheaterinfigure3.10.HeaterdesignedandbuiltbyStovemaster;photocourtesyofAlexChernov.

MasonryHeaters

Amasonryheaterisatrueradiantheatingsystem.Exceptfordoorsand

sometimeschimneydampers,thewholeconstructionisofmasonry.Theoperatingprincipleissimple:Theheatfromawoodfireisabsorbedbythelargemassofmasonryconstruction.Oftenthisisaugmentedbyamazeoffluesrunningbetweenthefirebox(wherethewoodburns)andthechimney(throughwhichtheremainingwarmexhaustexitsthehouse).Thevariousfluesdirecthotexhaustgasesfromthefireagainstasmuchmasonryaspossible.Thismassbecomeswarmandradiatesthatstoredheattotheenvironment.Mostoperatingmasonryheaterswillhavesurfacetemperaturesrangingfrom

120°to200°Fmostofthetime.Ofcourse,thesurfacetemperaturewillvarywiththequantityandqualityofthefuelthatisburnedaswellastheexactmaterialofwhichtheheaterismade.Itwillalsodependonhowoftenthemasonryheaterhasbeenused.Forexample,amasonryheaterbeingusedinthefallinahomeincentralKentuckymayonlygetfiredonceeverytwodays.Inthiscase,thesurfacetemperaturesmightstayquitelow.ButinahomeinnorthernMichiganinJanuary,theheatermaygetfiredasmuchastwiceinoneday,andsurfacetemperaturesmayaverage140°to175°.Thereareactuallymanyfactorsthatwillaffectbothhowthemasonryheaterisusedandhowhighitssurfacetemperatureswillbe.(Thesefactorswillbeaddressedingreaterdetailinchapter8.)Themajorpointisthatundermostconditionsofheating,themasonryheaterwillhavemuchhighersurfacetemperaturesthanother“radiant”heatingsystemssuchaswarmfloors.

TheVerticalRadiantHeatAdvantageMostofushaveexperiencedanearly-autumndaywhentheskyisclearandblueandthesunishighinthesky.Thetemperatureis65°Fandthereisnowind.Onsuchadaywefeelthesunatitsbest.Thewarmthpenetratestheskin.Witheyesclosed,wecanfeelthesunfirstononeshoulder,thentheback,thentheothershoulder.It’saluxurious,deeplyfelt,deeplymemorableexperience.Tobestandinginthesunonsuchadayistofeelthewarmthofamasonryheater.Amasonryheaterisusuallyaverticalstructure.Mostrangeinheightfrom

about3feettoaround7feet.Humanbeingsareverticalbeasts.Exceptwhensleeping,coveredbysheetsandquilts,peoplestandandsitvertically.Likethemasonryheaters,mostpeopleare3to7feettall.It’saperfectmatch.Humanbeingsradiateheat.Masonryheatersradiateheatmoreintenselythanpeopledo.Theresultisthatpeoplenearmasonryheatersfeelthewarmththesameway

theyfeelthesun.Theheatfromthesunandfromamasonryheaterisgenuineheat,insteadofinsulationagainstthelossofheat.

FIGURE3.10.Thisisthebacksideoftheheatershowninfigure3.9.Thebakeovendoorisontheright,andheatedseatingonthefarleft.Noticehowthetilepatternisechoedinthefloor.It’salifetime,heirloomheater.HeaterdesignedandbuiltbyStovemaster;photocourtesyofAlexChernov.

Onceyoureallyhaveanunderstandingofradiantheat,it’seasytoseewhyitismoredesirablethanmostotheroptions.Really,whocouldprefertohaveblowinglukewarmairwhentheycouldhavethewarmsunontheirshoulders?Gentle,radiantheatcanbefeltassoothing,penetratingheatfromadistance.Gentle,radiantheatisfeltbypeoplewhoexperiencethesunoramasonryheater.Amasonryheaterheatspeoplefromheadtotoe.Theinfraredraysfromaverticalmasonryheater“see”thewholefaceorprofileofanindividual.Thefeet,legs,torso,andheadareall“targets”forthatradiantheat.Inaddition,becausethemasonryheateriscontributingsignificantheatto

wallsandfurniturefromtoptobottom,thoseitemsarewarmerthaninaconventionallyheatedhome.Everythinginthevicinityofamasonryheaterhasahighersurfacetemperature.Withhighersurfacetemperatures,heatlossfromthebodytotheseobjectsisreduced.Coldspotsinaroomarelesslikely.Evenwindows,especiallythosewithalow-emissivity(low-e)coating,havewarmer

temperaturesanddrawsignificantlylessheatfrompeoplesittingnearthem.Themasonryheaterismuchwarmerthanthepeopleandthingsaroundit.At

just120°F,itis50°to55°warmerthanmostthingsarounditandatleast35°warmerthanpeople.Amasonryheateratfulloutput,withsurfacetemperaturesat150°ormore,hasanevenlargerradiantportion.Forthisreason,amasonryheaterispredominantlyaradiantheater,givingout70to80percentofitsheatintheformofinfraredradiation.Thisiswhypeoplewhowalkintoaroomwithawarmmasonryheaterknowrightawaythatsomethingspecialishappening.Somepeople,uponencounteringtheheatfromamasonryheater,mistakenly,orperhapsinnately,lookoutthewindowtolocatethesun.Theyknowthatfeelingsodistinctlyastheradiantwarmththatusuallycomesfromthesun.Masonryheatersheatallthings,includingwalls,floors,furniture,cups,china

dolls,dogs,cats,andpeople.Theinfraredradiationfromaverticalmasonryheaterwarmsanythingthatgetsinitsway.Theresultisthatevery“thing”becomesabatteryforheat.Eventheitemscastingheat“shadows”arebeingthoroughlywarmedsothatthey,too,becomeradiantheaters.Adividingwall,forexample,maygetwarmandprovideradiantheattotheroomonthefarsideofthatwallfromthemasonryheater.Attheveryleast,themuchhighersurfacetemperatureswillmakethemmorecomfortabletobearound,leanagainst,orsituponandwillinfluenceoverallairtemperatureaswell.Masonryheatersaddressradiantheatinaverypracticalway.Asvertical

animals,itmakessenseforhumanbeingstolivewithaverticalradiantheater.Theindividualinthechairinaroomheatedbyamasonryheaterisexperiencingfullsunlight.Thechair,theperson,thefeetonthestoolareall“solar”collectorsbeinghitconstantlywithradiantheatfromaverticalwallthatismuchwarmerthanthebodyandothersurfacetemperatures.Themasonryheaterpermitsallpeople,whethertheyaresittingonthefloor,sittingonasofawiththeirlegsup,orstandingatthekitchencounter,toexperiencedirectradiantheattoallpartsofthebody.Thisverticalradiantadvantageiswhyeverybodyexposedtoamasonryheater

istrulywarmed.Amasonryheaterisn’tjustpreventingexcessheatlossfrompeople,it’sactuallywarmingthem.Undertheseconditions,100percentofthepeoplepresentgetdirectlyheated,notjustthe85percenttargetotherheatingsystemsachieve.Everypersoncanfindaspotthatsuitstheirindividualwarmthrequirements.Amasonryheateristheonlytypeofheaterthattrulyheatsthehouse,everything,andeveryoneinit.Eachpersoncanexperiencewarmthtothe

levelofhisorherneed.Onacoldday,someonewhocomesinthehousefromablusterywalkinthe

parkmayperhapswanttositascloseaspossibletosomethingverywarm.Themasonryheaterprovidesthatverywarmspot.Thispersoncanpullachairrightnexttotheradiantstonesoftheheater,orsitonthebuilt-inbenchesandgetthemaximumheatbenefit.(Masonryheaterscanalsobeenjoyedfordirectconductedheat.Oftenpeoplewillleanon,sitagainst,orlieonamasonryheaterjustasHeidididatherhomeintheAlpsandJancsididinoldHungary.)Ontheotherhand,thosewithhighmetabolisms,includingchildrenandactive

individuals,mayneverfeelcold.Thesepeoplemaynotbeinterestedinsittingrightnexttothemasonryheater.Instead,theywillbequitecomfortableacrosstheroomoreveninanotherroomandawayfromthestove.Anotherpersonwhohasnotbeenoutsidebutwhosecirculationisn’tallthatgreatmayfindtheperfectspottobejustafewfeetawayfromthemasonryheater.Additionally,aperson’sneedforwarmthmaychangeoverthecourseofa

day.Somemayfeelchillywhentheyfirstgetoutofbedinthemorning,butaftertheirmorningcoffeemayhavenotroublestayingwarm.Someoneelsemayfeelwarmmostofthetimebutwhengettingtiredattheendofthedayfeellesswarm.Later,thepersonwhogotwarmonthecozybenchesoftheheaterafteracoldwalkintheparkmovesacrosstheroomoncerecoveredfromthechilloftheoutdooradventure.Amasonryheateristheonlytypeofheaterthatworksperfectlyforeachindividual.Itautomatically,withoutelectronicgadgetsorotherbellsandwhistles,providesacomfortlevelforeveryoneinthehouse.

TheUltimateShadowsandtheConvectiveRemnant

Manypeople,afterreadingaboutthewaymasonryheaterswork,askaveryobviousquestion:“Howdoesoneheatthesecondfloororthebedroomendof

thehouseifthemasonryheaterisinthemainlivingarea?”Itisclearthattheshadowspreviouslydescribedarestillanobstacletotheradiantperformanceofamasonryheater.Whenamasonryheaterisonthefirstfloor,allthesecond-floorroomsareshadedfromitbytheinterveningfloor.Likewise,inasingle-storyhome,theremayberoomsseparatedbymultiplewallsfromtheheater.

Thesearetheultimateshadowsforamasonryheater.Thereislittlehopeoffeelingdirectradiantheatinaroomseparatedfromthemasonryheaterbymultiplewalls.Theseroomsareanalogoustoaforest;themainareainwhichthemasonryheatersitscanbethoughtofasameadowwithbrightsunshine.Aslongasyoustayinthesunnymeadow,you’llfeelthedirectwarmthofthesun.Whenyoustepamongthetrees,however,theexperienceofsoothingradiantheatisgone.Theimportantthingtonoticeisthattheabsenceofthedirectradiantheatdoes

notmeanthatyou’llfeelcoldinthewoods.Rather,whatisexperiencedisasimilarairtemperaturebuttheabsenceoftheradiantwarmth.Iftheairtemperatureis70°Finthesunnymeadow,itismostlikelynear70°underthetrees.Theairtemperaturemayevenbeexactlythesameinbothlocations,thoughusuallythetemperatureisslightlylessintheshade.Itisnecessarytothinkabouthowtheareasofthehouseareusedandhow

heatingenergycanbemostwiselyconsumed.InEurope,whereheatingwithmasonryheatersismorecommon,homeownersthinkcriticallyabouthowtheywillbeusingthehome.Ifthemainlivingareasareadequatelywarmedbyradiantheat,peoplemaynotbeinterestedatallinaddingsignificantheattodistantbedrooms.Afterall,mostpeople,Europeanornot,spendverylittletimeanywherebutinthemainlivingareasduringwakinghours.Whensleeping,theyareinabedwithpajamasandquiltsoverthem.Manyevenprefercoolerconditionsforsleeping.It’sirrelevanttoconsiderthelackofradiantheatinaroominwhichyou’llbecoveredwithquiltsandsleeping.Aslongasthesedistantrooms,then,arereasonablywarm,thereisnoreasontoexpendenergytointroduceradiantheattothem.FIGURE3.11.Conductionheatfromamasonryheatercanbeenjoyedviaseatsorbenches,andchildrenorpetswillalwaysfindthosespots.Thismassivegraniteheaterrestsdeadcenterinalargehome.Thisheaterboastscompletewraparoundheatedbenchesandabakeoveninthechamberabovethemainfirebox.PhotocourtesyofMaineWoodHeatCompany.

FIGURE3.12.Whenthere’samasonryheater,thereisalwaysawarmplaceinthehouse.Thisheaterofsoapstoneandstuccooccupiesoneendofalargeroom.Thechimneyissandwichedbetweentheheaterandthebuilt-inshelvesandwood-storagearea.It’sapictureofsimplicityandelegance.PhotocourtesyofNewEnglandHearthandSoapstone.

Ontheotherhand,ifaroomdistantfromtheprimarymasonryheaterwillbeusedoften,thesolutionmaybedifferent.Forexample,astudyorofficetuckedawayforprivacyandquietmaybefrequentlyused.Inthiscase,you’dconsiderinstallingasmallmasonryheaterinthisroom.Similarly,intwo-storyhomes,aheaterstackedontopofthemain-floorheatermaybeaviablesolution.(Formoreonthisoption,seechapters5and6.)Thisway,youcanuseradiantheatinthisoft-visitedspacewhenneeded,yetyouhavetheoptionofnotfiringtheheateriftheroomwillnotbeextensivelyusedoversomeperiod.

FIGURE3.13.Amasonryheaterwarmseverythingthatit“sees.”Thisoneseesboththelivinganddiningareasfromitscentrallocation.Theasymmetricshapeprovidesvaryinglevelsforplacingdecorativeobjects.Tileaccentscompletetheuniquelook.Underthewood-toppedbenchesarenichesforstorageofwoodorotheritems.Noticehowthechimneybecomespartoftheasymmetryanddecoration.PhotocourtesyofBiofire,Inc.

Earlier,Imentionedthat70to80percentoftheheatfromamasonryheaterisemittedasradiantheat.Theremaining20to30percentdoes,indeed,comefromconvectionheat.Therelativelysmallsurfacearea,combinedwiththemoderatesurfacetemperature(ascomparedtowoodstoves,forexample),ofmostmasonryheatersdoesnotlenditselftoagreatdealofairheating.Thisremnantofconvectionheat,combinedwiththehighersurfacetemperaturesofeverythingithasheated,iswhatpermitsamasonryheatertostillinfluencedistantareasofahomethatarecompletelyblockedfrominfraredradiation.Thenextroomoverfromtheheaterlocation,forexample,maybenefitradiantlyjustfromthatuninsulatedinteriorwall’sradiantcontributionintotheroom.Inotherwords,awarmwallwillbecomearadiantheatsourceitselfonceithasbeenwarmedbythemasonryheater.Asthethingsintheareaofthemasonryheaterbecomewarm,they,andthe

heateritself,influenceairtemperatureandincreaseit.Thismainlivingareathenbecomesthewarmestareainthehouse.Ourstudyofphysicstellsus,however,thatthisconditionistemporaryanddestinedtochange.Agentleconvectionairflowwilloccurthroughoutthehouseastheforcesofnatureworkatequallydistributingthewarmtheverywhere.Thisiswhyairtemperaturesthroughoutahomeheatedbyamasonryheaterarerelativelyuniform.It’simportanttorememberthatthemasonryheater(iffiredregularly)is

alwayswarm.Sothisprocessisongoing.Itisnotthecasethatdistantareasarecold,thenyoufirethemasonryheaterandthingsstarttowarm,thentheygetcoldagainlater.Sinceamasonryheaterstoresandradiatesheatforlongperiods,thereisaninherentstabilityintemperatureseverywhere.Unlikeahouse,withanormalfurnace,thatgetsverycoldassoonasthepowergoesoutandthefurnacecannolongeroperate,themasonryheaterisalwayswarmandcontinuestocontributewarmthtolivingspaceslongafterthefiredies.Unlikeheatingsystemsthatprimarilyheatbydistributionofwarmair,the

convectionflowcreatedbyamasonryheaterissoslowandgentlethatyouneverfeelitasmovingairagainstyourskin.Itismerelyasecondaryremnantofheatedairmakingitswaythroughthehome.Imustnotethatthissituationassumesamasonryheaterdesignedtoheatthewholelivingspaceofahouse,roomsdistantandclose.Amasonryheaterdesignedtoheatjustafewroomswill

dolittletocontributetowarmingtheairindistantareas;additionalheatingsourceswillbenecessary.

ThermalComfortFinaleThediscussionhasthuscomefullcircle.Whatitreallycomesdowntoisthatthemostcommontypesofheatingsystemspeoplechoosefortheirhomes,includingin-floorheating,aremainlyeitherconvectionor,well,convection.Convectionheatiswarmair.Warmairisathermalblanket.Athermalblanketdoesnotwarmanyone;itjustreducesheatlosstomaintaincomfort,muchliketheblanketunderwhichyousleepatnight.Convectionheatersarehigh-technologywaysofreducingheatloss.

FIGURE3.14.Aheaterisarealradiantheatsource,likethesun.Itactuallywarmspeopleandthehouse,notjustair.Thissoapstoneheaterfeaturessplitstoneandmassivesmoothstonesabovethefirebox.Amultisideddoorenhancesfireviewing.Thoughtheupside-downfunnelshapegivestheimpressionofsmokegoingstraightfromthefireboxupthechimney,thisisarealmasonryheaterthatredirectstheexhaustthroughfluesbeforeitgetstothefinalexit.PhotocourtesyofTulikiviCorporation.

Conversely,masonryheatersarethechoiceforarealradiantheatsource—likeasuninthemiddleofahome.Theymaintainahighenoughsurfacetemperaturethatyoucanfeelheatonyourfacefromacrossaroom.Theyaremuchwarmerthanaveragebodytemperature,sothebodytruly“soaksup”thatheatlikeasolarcollector.Masonryheatersprovidethermalcomfortintheformofrealheatgain.Andwiththemasonryheater’sverticalorientation,theradiantheatcontactsyoufromheadtotoe.Amasonryheater’sgentleradiantheatworksuniversally.Itautomatically,

withoutelectronicgadgetsorthermostats,providesacomfortlevelforeveryoneinthehouse.Closertoit,youfeeltheheatmoreintensely;fartheraway,lessdramatically.Itistheonlytrulyradiantheateravailabletodaythatuseswoodforfuel.Thoughitisclearthatmasonryheatershavedistinctbenefitswhenitcomesto

providingpeoplewiththermalcomfort,thisisjustthebeginningofhowbeneficialthisformofheatingcanbe.Thehealth,environmental,andotherbenefitsofmasonryheatersarediscussedinchapter4.

ALLINTHEFAMILY

DiamondisayoungLabrador/boxerwithdeepblackfur.Likealldogs,Diamondlovesawarmspot,andhefrequentlycanbefoundonthefloorrightinfrontoftheLudwigfamilymasonryheater.Oftenhewillsitdownandstareattheglassdoorasifexpectingtheflamestoappear.Likeothermasonryheaterpets,however,hehastowaitfortheeveningwhenthefamilyenjoysanotherfire.Diamondisnotoftenaloneinappreciatingtheflamesandthewarmthofthemasonryheater.DeanandJudyLudwighavesevenchildren.Everyoneofthemlovestheirheater.Deanputsitsimplywhenhesays,“It’slikeoneofthefamily.”Deansayshefirstlearnedalittleaboutmasonryheatersabouttwelveyears

agowhenheandJudyhadatimber-frameshop/studiobuiltontheirproperty.Thetimber-frameartisansuggestedtheyconsideramasonryheater,buttheydidn’treallyknowmuchaboutthemandoptedforanopenfireplaceandin-floorheatinstead.Sevenyearslatertheyconverteda450-square-footscreenedporchintoafour-seasonroom.Theyknewtheywouldhavetoeitheraddontotheexistingforced-airsystemofthehouseorfindanotherwaytoheatthenewlyenclosedspace.Thistime,theydecidedtoinvestinamasonryheater.TheypurchasedasmallTulikiviSoapstoneFireplace.Now,theyoftenwishtheyhad

donethesameinthestudiobuilding.“Youhavetorealize,”Judypointsout,“thatthisnewroomisalmostall

windows.Weprettymuchexpectedittobecoldinthewinter.”Deansays,“Notonlyisthisroomthemostcomfortableroominthehouse,butwecutourheatingbillforthewholehouse!”Heexplains,“Weaddedabout15percentontothesizeofthehouse,butwehaverealizeda20percentreductioninourheatingcost!”SincethefuelfortheTulikivicomesmainlyfromfallentreesintheir21.2acresofwoods,theonlycostistheirtimetogatherandsplitwood.Withafamilyofnine(includingthreehuskyteenageboys),thatprovestobeafairlypainlesstask.JudyexplainsthatOwen,theyoungestatfourteen,tookcareofmostofthe

woodpreparationhimselfthisyear(2009).Dietrich(sixteen)hadbeenmainlytakingcareofitthepreviouscoupleofyears.Havingcommittedhistimetothewoodgathering,Owenalsoseemstobeespeciallyattachedtothemasonryheaterandstartsthefiresonaregularbasis.Lookingatthesoapstoneheater,though,itbecomesclearthateveryoneinthe

familyisattached.SoapstonefromtheTulikiviCorporationisgenerallyasoft,lightgraycolor.Sometimesthesamesoapstoneisusedforcountertops,forwhichitistreatedwithmineraloilthatturnsthestonecharcoalgrayordeepgreen.TheLudwigchildrenembracetheTulikivisomuchthat,overtheheatingseason,theTulikiviturnsthatdarkcharcoalcolorfromtheoilsintheirskin.WhileJudyandDeantalkabouttheheater,DietrichandOwenstandagainstthemasonryheaterandcaressitlikethey’repettingDiamond,ratherthansoapstone.AlltheLudwigchildrenarehomeschooled,withJudybeingtheirprincipal

teacher.Deanisanadministratoratalocalcollege.Judyexplains,“Everythinghappensinthisroom[withtheTulikivi].”Shegoesontosaythatthemasonryheaterhasmadeanoticeablechangeinfamilydynamics.Priortohavingthemasonryheater,thechildrenwoulddispersetotheirbedroomsorsomedistantcornerofthehouseinthewinter.Now,withtheTulikiviinoperationsevenmonthsoftheyear,everyonewantstobeinthesameroomwiththewarmstoneandradiantheat.Afavoritespotisbetweentheheaterandthewall—aspaceofjustabout1foot.Theyoungestchildren,Carl,Kevin,andGrace,fiteasily,thoughOwenalsocanbefoundreadingbookswhilelyingonthefloorbehindtheTulikivi.Deancomplains,“Weshouldhavemadethatspacealittlebigger.Ican’tfitbackthere.”Deanneverthelessenjoyssoothinghisagingjointsandmuscleswiththeheatofthefireplace.Hepointsout,“That’ssomethingyou

can’tdowithforcedair.”

FIGURE3.15.TheLudwigfamilywiththeirmasonryheater,whichgetssomanyembracesthesoapstoneisdarkened.ATulikiviheaterinstalledbyMasonryHeaterStore.

WhileKevinandCarlcannotrememberlifewithoutamasonryheater,thetwooldest,JohnandTodd,arenowofftocollege.JudyremarksthatJohn,homeforChristmasvacation,washearduttering,“IlovethisTulikivi,”whileheleanedagainstit.Todd,theoldest,managestobetheonlyonecapableofwaginganyviablecomplaintabouttheTulikiviwhenheremarks,“Sometimesifyouopenthedoorfast,someashesgetpulledoutbythesweepofthedoor.”Deancorrects,“Butthatdoesn’thappenifyouopenthedamperfirst!”Thewholefamilyisverygladtheychosethiswayofheatingtheirnewroom.

Judyexplainsthat,asinmostrenovationprojects,theirbudgetdictatedmanydecisionsatthetimetheTulikiviwasadded.Inhindsight,however,shesays,“IfIhadhadanyideahowmuchwewouldlovetheTulikivi,Iwouldhavebeenpressingforheatedsittingbenchesandprobablyabiggerheater.”Dean,anavidbaker,suggeststhathewouldprobablyalsowantalargeronewithabakeoven

option.There’snodoubtyou’vefoundsomethinggoodwhennineoutofninepeopleinthesamefamilylikeitandwantmoreofit.And,lestweforget,Diamondlovesit,too.

FIGURE4.1.Asmallsoapstoneheateristuckedintoahard-to-usespace.Sometimesahome’sstructuralfeaturesintroducespacesthataren’tveryfunctional.Thisplacementofamasonryheatershowshowsuchanareacanbecomeacozy,warmnook.Thesittingareasofthisonearenotheatedinternally.Thechimneyflueishiddeninthewallbehindthetallerelementofthestove.PhotocourtesyofTulikiviCorporation.

T

PARTTWO

DesigningaPieceoftheSun

hevariousbenefitsofmasonryheaters,asdescribedinpart1,canonlybeexperienced,ofcourse,whentheheaterisused.Beforethemasonryheater

canbeused,itmustbebuilt.Beforeitcanbebuilt,itneedstobedesigned.Beforeitcanbedesigned,youneedtodeterminehowlargeitneedstobeandwhereitisgoingtofitintothefloorplanofyourhouse.Youalsomustchooseamongarangeofadditionalfeaturesthatalldeserveconsideration.Amasonryheaterisahighlyspecialized,carefullycraftedheatingappliance.Thefollowingthreechapterswillgiveyouadetailedaccountofmanyoftheconsiderationsrequiredforgettingthemaximumreturnontheinvestmentinanheirloomheatingappliance.Thesechaptersand,indeed,thisentirebook,arenotareplacementforan

experienced,educated,andresponsiblemasonryheaterprofessional.Theywill,however,helpthefuturemasonryheaterownermakemanyimportantdecisions.Thesepagesaremeanttogiveyouallthetoolsyouneedtounderstandwhatthewholeprojectentailsandwhatyoucanexpecttohavetodecideastheprojectunfolds.Thisisnottosaythatyoucouldn’tusetheinformationinthisbookand

subsequentlyassumeado-it-yourselfproject.Individualswithmasonryexperience,inparticular,willfeelhighlyqualifiedtotacklesuchaventure.Myownexperiencehasbeen,however,thatsurprisinglysmallmisunderstandingsorassumptionssometimesleadtoexpensive,nearlyirreversible(read:expensive)defectsthatcansignificantlydiminishthefunctionalqualitiesofaninstallation.Forambitiousmasons,Ihopethatthisbook,andthispartinparticular,willstimulateadesireforprofessionaldevelopment.Forinterestedhomeowners,Ihopethematerialpresentedherewillstimulatetheaskingoftherightquestionsofsomeonewhomaybehiredtobuildamasonryheater.Ifyou,havingreadthismaterial,knowmoreaboutthesubjectsthanthebuilder,aredflagiswaving.Chapter6discussesthedesignitself—includingmaterialoptions,shapes,

sizes,materialproperties,andmore.Chapter7tellshowtodeterminewhatsize

ofmasonryheateryou’llneedforagivenlivingspace.Therearesomanyoptionstoconsideronceyoustartexploringallthepossiblefeatures.Beforespecificslikeprecisedesign,materials,andevensizeareconsidered,it’swisetoexploreexactlywhereamasonryheatershouldresideasapermanent,lifelongfriendandcompanionofyourfamily.Theoptionsarediscussedinchapter5.

FIGURE5.1.Acentrallylocatedbrickmasonryheater.Thisoneboastsalargeheatedbenchtotheleft,a“white”bakeoventotheright,andlimestoneaccents.Noticethekeystoneabovethedoorandtheinlaidstonepartwayupthechimney.Figures3.5and4.6showotherviewsofthisheater.

CHAPTERFIVE

Location

ImagineaLamborghinisportscar,say,aLamborghiniGallardoSpyder,asleek,glistening,beautifullyengineeredautomobile.Ithasa502-horsepower,turbochargedenginecapableoftakingthisvehiclefrom0to60milesperhourin3.8seconds.Thetopspeedis195mph.IthasPirellitires,alloyrims,frontandrearindependentsuspension,andasix-speedmanualtransmission.Ofcourse,it’salsoametallicRossoLetoRedconvertibleandhasblackleatherracingbucketseats.Everythingaboutitsayshighperformance,speed,power,agility,andcontrol.Nowsupposeit’saSaturdayafternoon;aclear,sunnyday.Thecarisclean,

waxed,polished.Itjusthadatune-upandoilchange.Thetankisfullofgas.Whatbetterthingtodowiththisunbelievablesportscarthanto...lockitupinthegarage,right?Whatpossiblycouldbebetterthanleavingitaloneinthedark,coolgarageandgoingtosiplemonadeonthebackporch?Thosewhoaredie-hardenvironmentalistsarenoddingtheirheads:“Yes,

bettertoleavethatgas-hog,carbon-emitting,high-techpolluterwhereitcandonomoreharm.”(Afterall,itdoesonlyget9milespergalloninthecity.)Butthosewhohavedrivensportscars,thosewhohaveaneedforspeed,thosewhohavefondmemoriesoftheirfirstcar,firstrace,orjustanopenroadwithnoonearound,aresaying,“Younutcase,takethatthingoutforaspin.Itdoesn’tbelonginadark,dankgarageonadaylikethis!”

PutItintheBasement?

Thoseencounteringthemasonryheaterconceptforthefirsttimearepronetothinkingthattheperfectlocationfortheheaterisinthebasement.Thetonsofmass,combinedwiththeerroneousbeliefthat“heatrises,”leadstotheinferencethatthisheavy-dutyheat-producingthingshouldbedownbelow.Fromthatlocation,neophytesreason,theconstantheatoutputwillthenheattheentire

upstairslivingspacesimplybecausetheheatrises.Amasonryheaterisacentralheatingsystem.Likeaconventionalforced-air

furnace,itburnsitsfuelinasmall(comparedwithmostopenfireplaces)firebox,andalltheheatproducedisdistributedfromthatlocationtosurroundingareasofthespace.Thefactthatmostmasonryheaterswellexceedatoninweightandareheat-producingappliancesmakesitreasonable,tomanypeople,toassumethatitsbestlocationisthebasement.

FIGURE5.2.Thismasonryheaterwasbuiltinabasementbecauseitwasremodeledandbecameaprimarylivingspace.Thered-brickheaterfeaturesalimestonemantelaswellaslimestone-cappedheatedwingbenchesoneitherside.Thebricksinthecentersquareabovethemantelareslightlyinset.Theownerplanstoonedayputhandmadetileshere.

Inreality,itisjustasridiculoustohideamasonryheaterinabasementasitistoparkthatLamborghiniinthegarageonaperfectdayfordriving.Neithercanbeenjoyedfullyifhiddenaway;bothachievetheirpotentialwhentheyareusedasintended.Chapter3addressedthecommonmisconceptionthatheatrisesanddescribed

theunusualradiantheatqualitiesofamasonryheater.Onceyoubegintograsptheconceptofgentle,radiantheat,itbecomesclearthatthebasementisonlyagoodplaceforamasonryheaterifthebasementisprimarylivingspace.Forsomesituations,thebasementisagoodlocationforamasonryheater.Thebest

thingtosayaboutlocationissimplythatamasonryheatershouldbeintheareaofahomeinwhichpeoplespendthemostwakingtime.

PrimaryLivingSpaceThehouseIgrewupinwithmybrother,mother,andfatherwas,bytoday’sstandards,small.Thefinishedlivingspacecomprisedallof1,100squarefeet.Roughlyhalfofthatspacewasdevotedtothreesmallbedrooms,ahallway,andoneandahalfbaths.Theremainderwasakitchenwitheatingareaandalivingroom.Inthewintermonths,ifweweren’tinbedforthenight,wespentmostofourtimeinthelivingroomorkitchen.Period.Thelivingandkitchenareasweretheprimarylivingspace.TodaymyfamilyandIliveinahousemorethantwicethesizeofmyparents’

house.Ithasroughly2,400squarefeetoflivingspaceincludingfourbedrooms,twoandahalfbaths,arecreationroom,aformaldiningroom,alaundry/mudroom,alivingroom,andakitchenwitheatingarea.Wheredoesmyfamilyspendmostofitstime?Well,evenwithalltheroomwehave,theprimarylivingspaceisstillthelivingroomandthekitchen;it’sanareathathasnomorelivingspacethantheprimarylivingspaceofmychildhoodhome.Anyoneconsideringamasonryheaterneedstothinkclearlyaboutwhatisor

willbe(orwhatyouwanttobe)theprimarylivingspace.Itpaystoreflectonhowthelivingspaceinyourcurrenthomeisused.It’sagoodbetthat,ifyou’rebuildinganewhome,itssimilarspaceswillbeusedinsimilarwaysforsimilarlengthsoftime.Anadditionto,orremodelingof,anexistinghomelikewisemaynotsubstantiallychangethewayprimaryspaceisused.WhatI’lldesignateasprimarylivingspaceisthedefaultlocationwherethevariousmembersofthehomearemostlikelytobefoundduringwakinghours.Thisanalysisiscriticalwhencontemplatingamasonryheater.Thereasonis

thatamasonryheaterismoreakintoadearfriendandcompanion—whoalsohappenstobegenerallypopular—thanitistoafireplace.Adearfriendandcompanionissomeonewithwhomalotoftimeisspent.Goodfriendswanttobetogether,tobeclosetoeachother.Apopularindividualattractspeople.Everyonewantsachancetobearoundhimorher.Amasonryheater’sgentlewarmthislikewiseapeoplemagnet.Thisconceptoftheheaterascentraldiffersfromthatusedbymostarchitects

anddesignerswhospecifyafireplaceforthehome.Often,totheseindividuals,afireplaceisneitherafunctionalheatingappliancenoracrowd-pleasingpersonalitytothedegreeI’memphasizinghere.Tobesure,designersappreciatetheambienceofafireandrecognizethatafiredoesattractpeople.Thedifferenceiscrucial,however.Afireismesmerizingtowatch,andafireplacecanbebuiltanddecoratedto

beanattractiveornament.Afirethatisnotmeanttocontributesignificantlytoheatingaspaceisadelighttowatch,butisrelativelyvaluelessasawarmcompanion.Aconventionalfireplacefunnelsmostoftheheatitproduces,alongwithheatedroomair,upthechimney.Thecommonfireplace,then,isadecorativeamenity;indeed,manynew,modernfireplacedesignslookmorelikeframedpicturesthantheydoactualfireplaces.Thisisthereasonthatarchitectssocommonlyplaceafireplaceagainstawallasafocalpoint,ratherthanplacingitwithintheheartofthelivingspaceasagatheringpoint.

FIGURE5.3.Amasonryheaterisbestplacedcentrallyinthemainlivingareaofthehome.Thisbluestoneheaterservesasaroomdividerbetweentheeat-inkitchen,thelivingroom,andahallleadingtootherpartsofthehouse.Theviewisfromthebalconyandshowstheentire18-foot-tallchimney.Theheateritselfissix-sidedwiththechimneycomingoffoneofthetriangularsides.Anotherviewofthisheaterisinthephotoatthebeginningofpart4.

Primarylivingspaceisbestoutfittedwithamasonryheaterwhenyourealize

thatthemainattractionofamasonryheaterisnotthefireitself,butthesteadywarmththatradiatesfromthemass.Thefireitselfcanalsobeenjoyedinanymasonryheaterwithglassdoors,but,likeanattractiveperson’sappearance,itisonlythesparkthatignitesaneveningofconversation.Amasonryheaterisnotawallflower;itisanappliancewithadepthofcommitmenttoyourcomfortandwell-being.Theheater’sdiscourseisitsunbendingintenttomakeitscompanycomfortable.Likeanattractivepersonwithanintelligentmindandagoodsenseofhumor,amasonryheaterissomethingyoulongtobearound.

TheCenterofAttentionandaGatheringPoint

Whileconventionalfireplacesareoftenthefocusofattention,aproperlyinstalledmasonryheaterbecomesthecenterofattention.Thisisnotinthesensethatthosearounditcanonlyfocusonitandwhatit’sdoing.Thosewholivewithamasonryheaterorfindthemselvesnearonedon’tusuallyspendalltheirtimeadmiringitsappearanceoritsperformance.Itis,rather,thecenterofinstinctualattention.Likesunshinewhenyou’recold,orfoodwhenyou’rehungry,orlightwhenit’sdarkoutside,peopleautomaticallygravitatetowardtheareainwhichtheheaterexists.Themasonryheateristhegatheringpoint,ratherthanthefocalpoint.Youcanobservethisinstinctualactivityaroundacampfireonasummer

evening.Veryseldomdoesanyonewalkawayfromthecampfiretominglewithothers.Everyonegathers,instinctively,aroundthefiretotalk.Ifcomfortablechairsweresetupinacircle,facingoneanother,somedistancefromthefire,you’dseethepeopletakingthechairsandmovingthemaroundthefire.Ifthechairswerehardtomove,they’dstandaroundthefireorsitontheground—butgiventhechoice,theywouldn’tlikelystayawayfromthatfire.Thissamebehaviorpersistsaroundamasonryheater.Itisthereforeimportant,

oncetheprimarylivingspaceisdefined,toimaginewhatthebestspotisforthiskindofgathering,whetherit’sasmallgatheringofjusttheimmediatefamilyoralargergatheringoffriendsandfamily.Planthespacefortheexpecteduse.Ifyouentertainonaregularbasis,yoursolutionwillbedifferentthanforahomewhereonlytheimmediatefamilywillbearound.Thespaceforentertainingneedstobelargerandmoreopen,whileasmallfamilymaysimplygatherina

modestdiningareaorfamilyroom.

FIGURE5.4.Themasonryheaterisagatheringpoint.Thisonehasasee-throughfireboxandsportsafullyfunctional“black”bakeoven.Thisheatercanbeseeninbetterdetailinfigures3.1,6.31,and6.36.HeaterbyMarenCookeandKenMatesz;photobyMarenCooke.

Theaspectofentertainingand,particularly,cookingfigureintothelocationdecisionaswellifyouhopetoincorporateabakingovenormasonrycookstoveintothemass.Thereisanobviousdisconnectinhavingafireplacewithabakingovenlocatedaroomawayfromthekitchen.Itmayseemobvioustomostpeopletohaveanovenfacingthekitchenor,attheveryleast,adiningarea.Thisdoesnotstoppeoplefromforgettingthisdetailwhenmakinginitialplans.Theovenisfunctional,ofcourse,whereveritislocatedinthehouse.Itisfarbetter,however,tohaveitinaroominwhichfoodiseitherpreparedoreaten.

MorethanOnePrimaryLivingSpace?

Itispossibletohavemorethanoneareainthehomethatgetsalotofdaytimeuse.Forexample,someonewhoworksathomemayhaveanofficeorden.Other

popularroomsarerecreationrooms,theaterrooms,sewingrooms,orotherspecialtyroomsinwhichoneormorepeoplegooften,usuallyforspecifickindsofactivities.Althoughit’struethatthesespacesgetregularuse,theydon’tquitefittheclassificationofprimarylivingspaceasit’susedhere.Primarylivingspaceisstilltheoverriding,defaultlocationinahomewhereyou’remostlikely,atanygiventime,tofindthemajorityofthefamilymembers.Officesandspecialroomsarejustthat:specialareas.Whendesigninganew

home(orexpandinganexistinghome),considerthemeritsofcreatingthesespecialareasseparatelyfromtheprimarylivingareas.Iftheymustbeseparated,perhapstheyalsodeservetheirown,smallmasonryheatertobringradiantcomfortthereaswell.Anotheroptionistolocatetheseareasasappendagesimmediatelyaccessibletotheprimarylivingspace.Afterall,ifyou’regoingtobehomeallday,won’tyouwanttobenearthemostcomfortablearea?

FIGURE5.5.Hereisanheirloom-qualitysoapstoneheaterperfectlylocatedforenjoymentandheatingofthelivingspace.Largesplitorrock-facedsoapstoneblockscreateagentlytaperedheaterbodyrisingfromlightlysupported,cantileveredwingbenches.Itslocationbetweenthelivingroomandkitchen,nearthestairs,andalsovisiblefromthefoyergiveitacommandingposition.PhotocourtesyofWarmStoneFireplacesandDesigns;photocopyrightJKLawrencePhotography.

Thebestoptionissimplytothinkcarefullybeforecreatingaspecial-use

space.Forexample,youmaybelievethehomeofficemustbeaseparate,privatespacesoyoucanconcentrateandgetworkdonewithoutinterruptionfromotherpeopleandactivities.Butifit’smorelikelythatyou’llbetheonlyonehomeduringtheday,whoistheretodistractyou?Willahometheaterorentertainmentroomreallyimprovelifesubstantiallyoveragreatroomthatiswellequippedformoviesandgames?Alltheseareindividual,subjectivechoicesthatneedtobemeasuredagainstcosts,reasonableness,andlong-termlifeinahome.Anexpensiveentertainmentroomforthekidsmightsoundterrific,untilyouconsiderthatthekidsmightbemovingoutofthehomeinfourorfiveyears.Thisbookassumes,aboveallelse,thatifyou’reinterestedinmasonryheaters,

you’relikewiseinterestedinamenitiesthatresultinpermanentimprovementsinthecomfort,pleasure,andutilityofahome.Heirloombasicslikehigh-qualityframingandinsulation,coupledwithheirloomartifactslikehigh-qualitywindows,floors,cupboards,counters,andmasonryheaterswillgenerallybenefitafamilyandfuturegenerationsregardlessofchangesinavailabilityofnonrenewableresources,trends,ortechnology.Thiswillbethecasewhethertherearetwopeoplelivinginthehomeorafamilyoften.Thesamecan’tnecessarilybesaidforamenitiespurchasedforasingleuseorbenefitliketheaterorentertainmentroomsorhigh-techheatingandair-conditioningequipment.Asmentionedearlier,it’sthefundamentalsthatcount.Thesimplefactisthatamasonryheatercanhaveamuchmorepowerfulpull

onpeoplethanyourealizeatfirst.Ifyouappreciateitsfeaturesandbenefitsandplanwaystomaximizeenjoymentofthosebenefits,youwon’tbedisappointed.Easilythesinglemostimportantsteptomaximumenjoymentislocatingthemasonryheaterinthemostfavorablegatheringareaoftheprimarylivingspace.

TheChimneyRulesOnceyou’veestablishedtheprimarylivingspace,it’stimetofigureouttheexactlocationforthemasonryheater.Giventhatmanymodernhomeshavequitelargespacesandthatroomshave(often)fourwalls,therearestillmanylocationsinwhichthemasonryheatercouldserveitspurposeasthegatheringpoint.Thefactthatamasonryheaterneedsachimneywillhelptofurtherrefinethislocation.Often,peoplewhoseeamasonryheaterforthefirsttime,eitherinpersonor

inpictures,supposethattheapplianceactuallyneedsnochimney.Inmanyinstallations,thechimneyisn’tvisiblebecauseit’sinachasehiddeninawallbehind,tothesideof,orsomedistanceawayfromthefirebox.Thetruth,ofcourse,isthatanysolid-fueledheatingapplianceneedsachimney.Somepeoplewillinquirewhetherthemasonryheatercanjustbe“direct-vented”outitsbacktotheoutside,likesomegasappliances.Thesimpleanswerisno.Amasonryheaterworksentirely(well,almost)byvirtueofachimney.

Withoutaproperlyoperatingchimney,themasonryheaterwon’tfunctionproperly.Howdoyouknowifthechimneyisoperatingcorrectly?Quitesimply,achimneyisworkingcorrectlyiftheexhaustoftheappliancealwaysgoesupthechimneyundernormaloperatingandlivingconditions.Achimneythatworkssometimesoronlyundercertainconditionsisnotachimneythatoperatescorrectly.Forexample,ifachimneyworksonlyifthewindcomesfromacertaindirection,it’sadysfunctionalchimney.Aswithmostthings,itispossibleto“make”adysfunctionalchimneywork.It’smuchbettertoplantohaveafullyfunctionalchimney,however.

ThePhysicsofChimneysWithabasicunderstandingofthephysicallawsbehindgoodchimneyperformance,itbecomeseasytoenvisionthebestsiteforachimney.Knowingthislocationwillhelpyoudecidewhere,intheprimarylivingspace,toputthemasonryheater.Webster’sNewWorldDictionarydefineschimneyas“thepassageorstructure

throughwhichsmokeescapesfromafire,oftenextendingabovetheroof.”Thisdefinitioncanbeimprovedbysayingthatthechimneyisastructurethroughwhichexhaustfromafireisdirectedverticallyoutofahouse.Thetermverticallyisnecessarytoclarifythefactthathorizontalstructuresthatconnectamasonryheaterorotherappliancetoachimneyare,indeed,connectors,butnotchimneysthemselves.Gentlyangledportionsofchimneysarestillvertical,inthesensethattheyserveonlytomodifythelocationoftheverticalchimneyslightly,anddolittletorestricttheoverallverticalmovementofexhaust.Inordertounderstandgoodchimneyfunction,itisnecessarytorevisitthe

commonstatementthat“heatrises.”Asdiscussedinchapter3,heatitselfdoesnotrise.Itismoreaccuratetosaythathotorwarmairrises.Inaproperlyoperatingchimney,then,warmexhaustgoesupthechimneyandoutofthe

house;theapplianceworksproperlyandnodusty,objectionable,potentiallyharmfulgasesenterthelivingspace.It’stimetoexaminemorecloselythestatementthatwarmairrises.

DoesWarmAirAlwaysGoUpaChimney?

Fewpeople,savephysicistsandengineers,everponderthisquestion.Mostofussimplyacceptthatwarmairrises,justasweacceptthatobjectsfalltothegroundwhendropped.Anyone,however,contemplatingtheuseofawood-burningmasonryheatershouldbefullyawareofthecompleteanswertothisquestion,becauseitwillleadtoanunderstandingofhowtoplaceamasonryheatersothatitattainsmaximumperformanceandprovidesmaximumenjoymentfordecadestocome.Somewillquicklyanswerthequestion,sayingthatofcoursewarmair

(exhaust)willalwaysriseupachimneybecauseitislighterthancoolerair.Warmairismorebuoyantthancold.Whenairgetswarmed,itexpands—itsmoleculesspreadout—makingitlighter(lessdense)thancoolerair;soindeedwarmairdoesrise.Manyfireplaceusersneverthelesshavebeenfrustratedandaggravatedoverexhaust(smoke)thatdidnotgoupthechimney,butrathercameintothehome,stainedthefrontofthefireplace,ormuchworse.Ifthechimneyiswideopenandtheexhaustofthefireiswarmerthanroomair,whyisn’titrisingupthechimney?Youmayrecallthesecondlawofthermodynamics(seechapters1and3),

whichstatedthatheatalwaystravelsfromthewarmerareatothecoolerareaandnottheotherwayaround(withoutanenergyinput).Inasimilarfashion,air(oranyotherfluid,liquid,orgas)willalwaystravelfromanareaofhigherpressuretoanareaoflowerpressure.Thisadditionalunderstandingcombining“hotairbeinglighter”and“airunderhigherpressuremovingtoanareaoflowerpressure”iscrucial.Ifallweneedtoknowisthathotairislighter,thentherewouldbenosatisfactoryanswerastowhymanycommonfireplaces,whicharejustfireboxeswithopenchimneysabovethem,frequentlyspillsmokeintothehouse.Thelighterwarmairshouldreadilyjustgoupthechimneyprovided.Obviously,there’smoretothisthanmeetstheeye.Thinkaboutwateringplantsinthegarden.Ifyouuseacommonhosenozzle

—thekindthatcansprayastreamorfanorvariousotherpatterns—andwhenyou’redonespraying,youshutthenozzleandgotothespigotonthehouseandturnoffthewatersupply,thehosewillbepressurized.Withthewatersupplyoff,youcouldagainpickupthehoseandopenthenozzle.Forabrieftime,

waterwillbeforcedoutofthehose,thoughthewaterspigotisoff.Thewaterinthehosehadbeenunderhigherpressurethanthesurroundingenvironment.

FIGURE5.6.Likemanymasonryheaters,thisoneappearstohavenochimneybecausethechimneyisbuiltintothewall.Itusesterra-cottatilestocontrastwithstucco,aswellasnichesanddecorativeshapesforgreatappeal.Noticethattheblackloadingdoordoesnothaveglass.Sinceamasonryheaterisusedonlyforpartoftheyearinmostlocations,manyfolksdon’twanttolookintoanemptyfireboxduringthosewarmseasons.Otherswouldnevergiveuptheoptionofseeingthefire.PhotocourtesyofBiofire,Inc.

Orthinkofthepainfulexperienceofgettingaflattireonabike,car,ormower,andhearingtheair,onceundercontainedpressureinthetire,whistlingoutofthepunctureuntiltheairpressureinsidethetirematchestheairpressuresurroundingit.Thesecommonoccurrencesaredemonstrationsofthegeneralideabehind

chimneyperformanceaswell.Exhaustfromanappliancewillgoupthechimneyandoutofthehouseonlyiftheeasiestwayforairunderhigherpressuretoleavethehouseisupthechimney.Itmattersnothowexpensivethechimneywas,howbigorsmallitsdiameter,whetherit’sbrick,claytile,refractory,ormetal.Theonlyrealfactoriswhetherthechimneywasdesignedtobethebestplaceinthehouseforpressurizedairtoescape.Insimplerterms,thechimneyneedstobethe

bestleakinthehouseenvelope,theconditionedlivingspace.

StackEffect

Thinksmokestack.Sinceitisknownthathotairtypicallyrisesoutofachimney(a“stack”),stackeffectisthenamegiventothisphenomenon.Itcanbedefinedmoreaccuratelyas“thedifferenceinpressurecreatedbythedifferencebetweentheairtemperatureinacontainercomparedwiththeairtemperatureoutsidethatcontainer.”Thisdefinitionrecognizesthatbothtemperatureandpressureplayaroleinaproperlyoperatingchimney.Stackeffectisn’tpresentonlyinchimneys,however.Stackeffectrelatestoanycontainer.Ahouse,likeachimney,isacontainerofairandit,too,isasortofchimney.

Afterall,inthewinter,it(hopefully)containsairthatiswarmerthanoutsideair.Justasinatruechimney,thewarmairinahousewillwanttorise.Sincemosthomesarenotairtightplasticbags,theygenerallyhavetinyleaksthroughwhichoutsideaircanenter,andinside(warm)aircanleave.Ingeneral,outsideairwillleakintothehomeinalowerlevelandwarmairwillleakoutofthehouseatanupperlevel.Thehouseisthusperformingthesamewayachimneydoes,funnelingwarmerairoutits“top.”

ThePressureIsOn

Thisconditionofairenteringlowandexitinghighgivesacluetothegeneralairpressureconditionsexistinginthehome.Ifairisenteringthehouseonthefirstfloor,theairpressuretherehastobenegativeorlowerthantheoutdooratmosphericpressure.Ifthewarmairisbeingforcedoutoftheleaksonthesecondfloor,forexample,thenthesecond-floorareamustbeunderpositivepressure(higherpressurethantheatmospheric,outdoorairpressure).Thisisknown,again,becauseairalwaysmovesfromanareaofhigherpressuretoanareaoflower.Airatatmosphericpressurerushestotheareawherethepressureislow,andairatapressurehigherthanatmosphericrushestowardtheoutsideofthehouse,wherethepressureislower.Theair-temperaturedifferenceiscreatingthedifferentpressureregions.Somewherebetweenthenegativepressureareaandthepositivepressurearea

isanelevationwherethepressureisneitherpositivenornegative.Thisiscalledtheneutralpressureplaneorneutralpressurezone.Attheneutralpressureplane,theairpressureisthesameasoutdooratmosphericpressure.Hereairwillneitherbedrawninnorexpelledfromthehouse.Belowtheneutralpressureplaneisthevolumeofthehousewithpressureslowerthanatmospheric

(negativepressure),andaboveitisthevolumeofthehousewithpositivepressure.Thelocationoftheneutralpressurezonevariesfromhousetohouse,butin

mostmodern,reasonablywell-builthomes,theneutralpressureplaneissomewhatabovetheverticalmidpointoftheheatedenvelopeofthehouse.Inacommontwo-storyhouse,forexample,builtoveracrawlspace,theneutralpressureplaneislikelytobeatorabovetheactualfloorlevelofthesecondstory.Likewise,ahomewithafullbasementandtwofullfloorswilllikelyhavetheneutralpressureplaneabovethemidlineofthefirstmainfloorabovethebasement.

ConnectingAirPressurewithChimneyFunction

Sinceboththeentirehomeandthechimneyofanoperatingmasonryheateraresubjecttothestackeffect,thinkofthechimneyasbeingachimneyinsideachimney.Boththehouseanditschimneyaresystemsthatcontainairathigherpressurethatwantstoescapetoanareaoflowerpressure.Botharesystemscontainingairthatiswarmerthantheairoutsidethem.Thechimneyinoperationcontainsexhaustthatiswarmerthantheairinthehouse,whilethehouseconfinesairthatiswarmerthanoutside.Stackeffectoperatesinbothstructures,andit’sthepressureconditionsthatdeterminewhichsystemisthebetterchimney.Inotherwords,ifthepressuredrivingwarmairtotheupperpartsofthehouseisstrongerthanthepressureattemptingtodriveexhaustupthechimney,theexhaustwillcomeoutofthemasonryheaterandintothehouseratherthangoingupthechimney.

FIGURE5.7.Byproperlylocatingachimney,youcanmakesurethesmokealwaysgoesupandawhitestuccoedheateralwaysstayswhite.Thisgranite-trimmedheaterhasanupper-chamber“black”bakeoven.Throughthearchedbakeovendoorglass,youcanseethefountainofflamethathasjustcomethroughthethroatfromthemainfireboxbelow.Noticewoodstoragetotheleftandthemasonrychimneytransitioningtostainlesssteelontheright.PhotocourtesyofMaineWoodHeatCompany.

Asnotedabove,theneutralpressureplaneofatypicalhouseisaboveitsverticalmiddleplane.Theprimarylivingspaceofmosthomestendstobeonthefirstlevel,andthemasonryheaterisusuallyintheprimarylivingspace.Themasonryheater,then,isusuallyinthepartofthehousebelowtheneutralpressureplane,intheareawithapressurelowerthanoutsideatmosphericpressure(negativepressure).Thisisthepartofthehousethatwantstodrawairintothehousefromoutside.Ifthepressurecreatedinthechimneyisnotgreaterthanthisnegativepressure,thenegativepressurewillpullair(andmasonryheaterexhaust)intothelivingspacethroughthechimney—whichfunctionsthenasadirectconnectiontooutdooratmosphericpressure.Ingooddesign,thereversehappens:Thetemperaturedifferencethatwantsto

drivetheflowofexhaustupthechimney(calledthedraft)isreliablystrongerthanthehousestackeffect.Inthiscase,thechimneyandapplianceworkproperly;alltheexhaustgoesupthechimneyeverytimetheheaterisused.

TheChimneyRules

Ofcourse,theeffecteveryonewantsisforthesmoketogoupthechimneyandnotintotheroom.Amasonryheaterisalifetime,maybeevenamulti-lifetimefireplace.Itstandstoreason,then,thatwisdomwouldhaveeverymasonryheaterequippedwithachimneythatwillreliablysenditsexhaustupthechimneyandnowhereelse.Sincemostmasonryheatersarelikelytobeinstalledbelowtheneutralpressureplaneofthehouse,everyattemptshouldbemadetoinstallachimneythatwillalwaysovercomethenegativepressureinherenttothatlocation.Fortunately,therulesformakingthishappenarefewandsimple.Anyonewhohasamasonryheaterinstalledandfollowstheseruleswillbeblessedwithmaximumperformanceoftheappliance:

1.Planforthechimneytobelocatedwithintheheatedconfinesofthehome.

Thebasisforthisruleissimple:Ifthechimney(andtheairinit)isalreadyatroomtemperature,itisreadyatalltimestobecomethebestplaceforexhaustto

leavethehouse.Thechimney,inessence,isthebest“leak”inthehouseenvelope,justwaitingforthemasonryheaterdoororchimneydampertobeopened,atwhichpointimmediatedraftwillbeginbecauseofstackeffect.Achimneyoutsidetheheatedspace,ontheotherhand,will,inthewinter,

containcoldair.Thisairiscolderthanroomairand,dependingonchangingweatherconditionsandmass-storagefactors,couldalsobecolderthanambientoutdoortemperatures.Thisisnearlyasurefirewaytomakethehouseabetterchimneythanthechimneyitself.Thehouse,operatingundernaturalstackeffect,willpullmasonryheaterexhaustintothehouse.Theheatofthefiresimplywillnoteasilyovercomethestackeffect,thedraft,ofthehouseitself.FIGURE5.8.Thechimneyhereiscompletelyinsidethehouseandexitstheroomveryclosetotheridgeline.Thiswhitestuccoheaterutilizesthesystemoffreegasmovementdescribedinchapter8andfeaturesheatedseatingandwoodstorageaswellasa“white”bakeoven.DesignedandbuiltbyStovemaster;photocourtesyofAlexChernov.

CHIMNEYSTHATCAUSEPROBLEMS

Thechimneyrulestendtokeepthechimneyinlocationswhereitwillexittheroofofthehouserelativelyclosetotheridge—thehighestpointoftheroof.Anotherverygoodreasonnottohavethechimneyclosetothelowestpointoftheroofisthatitcanbecomeamorelikelyplacetogenerateroofleaks.Achimneycomesthroughaholeintheroof.Thoughgoodroofingandflashingpracticeswillusuallypreventleaksaroundachimney,whenachimneyisdownstreamfrommostoftheprecipitation(andanythingelse)thatfallsontheroof,itismuchmorelikelytoaccumulatedirtorcatchtreebranchesandotherdebristhatcandegradethewatertightnessovertime.Ahole(chimneylocation)atthehighestpartoftheroofwillbesubjecttomuchlesswearandmuchlesswater—anadditionalprecautionagainsteventualleaks.

2.Ensurethatthechimneypassesthroughthetallestheatedpartofthehouse.

Stackeffectispoweredbythedifferencesintemperaturesandtheresultingdifferencesinpressures.Theheightofthestack(eitherthehouseitselforthechimney)alsoinfluencesthepressure.Atallerhousewillhavehigherpositiveairpressureintheuppermostfloorthanashorterhouse.Similarly,atallerchimneywillhavebetterdraft.Aslongasthechimneyservingamasonryheaterispassingthroughheatedspace(asperRule1above)allthewaythroughthe

tallest,heatedareaofthehouse,itwillcontinuetohavesuperiorstackeffectandprovidethebestventing.Ithassuperiordraftbecauseitisaswarmas,yettallerthan,thetallestheatedpartofthehouse;thepositivepressuresinitarealwayshigherthanthoseinthehouse.Itshouldbenotedthatthisruleautomaticallydiscourageshavingchimneys

anywherealongtheeavewallofaroomwithaslopedcathedralceiling.Thechimneydoesnothavetoberightattheapexofsucharoom,butitshouldbeveryclose.Thisrulealsodiscouragestheplacementofthechimneyinaone-storyadditiontoatwo-storyhouse.Additionally,followingthisrulekeepschimneys,particularlylargemasonrychimneys,frombeinglocatedatthelowpointsofaroofwheretheywillcollectmoreleavesandsnow,andbewashedbymorerain.Inotherwords,they’relesssubjecttocausingroofleaksormaintenanceproblemsastimepasses.

FIGURE5.9.Anexampleofachimneyoffsetfromaheatertoadesiredlocationfortravelthroughtherestofthehouseandthroughtheroof.HeaterbyNewEnglandHearthandSoapstone.

3.Avoidtheuseofpowerfulexhaustdevices.

Kitchenstoveexhausts,bathroomexhaustfans,andevenfurnaceswithassisteddraftfansventingtotheoutsidecansometimesbepowerfulenoughtodepressurizethehouse.Althoughnaturalstackeffectofthehousewillbeovercomebyachimneythatfollowsthefirsttworules,anexhaustfanisanotherstory.Bearinmindthattheactualairpressurethatachievespositivedraft—thepressuredrivingexhaustupthechimney—isstillveryweak.Thinkofhow

slowlyahot-airballoonrisesintothesky;itdoesn’trepresentalotofpower.Anelectricfan,ontheotherhand,maymovemanycubicfeetofairperminute,farsurpassingthemodestairpressuresofthedraftingchimney.Suchadevicecaneasilypullair(andexhaust)downthechimneyastheairpressurestryinvaintoneutralizethenegativepressurescreated.Intheconstructionphaseofahouse,it’spossibletoinstallamake-upair

devicethatautomaticallycompensatesfortheairbeingdrawnoutbytheexhaustfanwhenit’sactivated.Inexistinghomeswherethisautomaticfeaturehasnotbeeninstalled,beawarethatsuchappliancescanreversetheflowofexhaustinachimney.Simplyrefrainingfromusingthesehigh-volumefansduringthelimitedtimethatamasonryheaterisfiredwillassurethatreverseddraftsdonothappen.

4.Followtheadviceofthemasonryheaterprofessionalormanufacturerregardingchimneyheight.

Mostmasonryheaterprofessionalswillencourageminimumchimneyheightsfortheheaterstheyinstall.Asageneralrule,theyshouldsuggestachimneyatleast15feettall,andmanyheaterprofessionalswanttoseenolessthan20feet.Acommon,single-storyhomethatis24feetwideandhasan8-footceilingandshallowroofpitchwillhavearidgeheightofatleast12feet.Sincemostconstructioncodespertainingtochimneyswillrequirethechimneytobe2to3feetabovetheridge,evenamasonryheaterinthishousecouldhave15feetoftotalheight.Thegreatertheheight,themorepressurethatisdevelopedinthechimneyand,thus,thebetterthedraft.

Oflesserimportance,butfrequentlymentionedbystoveandfireplaceprofessionals,isageneralwarningnottoinstalloffsetsinthechimney.Offsetsareslightlyangledportionsofchimneythatareusedtomeetthelocationfromwhichthechimneyexitstheceilingorroof.Buildingcodes(seechapter9)and/ormanufacturer’sinstructions(forfactory-madechimneys)maylimittheangleandtotaldistanceoftheseoffsets.Becauseoffsetsinterrupttherapidverticalmovementofexhaustupachimney,theycantipthebalancetowardpossiblereverseflowofexhaustundersomeconditions.Ifthefourrulesabovearefollowed,thengradual,shortoffsetsarerarelyanissueformasonryheaters.Itiswise,however,toconsultwithaprofessionaltoseeifthere’sanyreasonoffsetscannotbeusedinagivenproject.Masonryheaterdesignersshouldfactoroffsetsintothedesignoftheheatertobebuiltbecauseanyoffsetwillchangethedynamicsandspeedofdraft,ifonlyalittle.

Sometimestheabove-mentionedoffsetsareusedtorelocateachimneyeitherbeforeorasitgoesthroughasecond-floorspace.Obviously,theprimelocationoftheheaterandchimneyonthefirstfloorormainlevelofthehomeoftennecessitatesthatthechimneytravelthroughthesecond-floorspace,ifthehomehasone.Innewconstruction,thelocationofthechimneymustbetakenintoaccountwhendesigningthehome’ssecondfloor.Thiswillbejustasimportantasthemain-leveldesign,inordertoassurethatthechimneycanbeproperlybuiltwithoutinterferingwiththespacedirectlyabovethemasonryheater.Thisisoneofthechiefreasonswhyamasonryheaterprofessionalshouldbeinvolvedduringthedesignprocess.Therearemanypossibilitiesthattheprofessionalwillbereadytosuggestforanysuchdilemmas.Inadvanceofhiringaprofessional,readthesection“MultistoryRetrofits”laterinthischapterregardingchimneyandheaterplacement.Therulesforchimneyplacementgoalongwaytowarddeterminingthebest

locationforamasonryheater.Withthelocationalreadynarrowedtotheprimarylivingspace,thechimney’sfunctionalrequirementsshouldbegintoarticulateazoneinthatspacethatwouldassuregoodchimneyperformance.Nowit’stimetogetreallyspecific.Amasonryheaterisjustaspermanentasthehomeitself,ifnotmoreso.Thefinaldecisionswillshapehowspacesareusedfordecadestocome.

FunctionalRequirementsofRadiantHeatAsIpointedoutpreviously,radiantheatiselectromagneticradiation.Inotherwords,itbehavesjustlikelightineveryway,exceptthatitisnotvisibletothehumaneye.Ifyouturnonalightinacloset,thenshutthedoor,anyoneoutsidetheclosetwillnotgettoexperiencethelightfromthebulb.Similarly,ifaheaterisconfinedtoasmallspaceboundedbywalls,youwon’tgettoexperienceitsradiantheatoutsidethosefourwalls.Asdiscussedinchapter3,thewallsofahousearetheultimateshadowmakersforamasonryheater’sgentleradiance.Ifyourintentioninhavingamasonryheaterisonlytoheatasingleroom,then

thislimitationisnotahindranceatall.Infact,thewell-definedspacewillenhancethecomfortyouexperiencethere.Assumingtheheaterisproperlysizedtothatspace,itwillgentlyheateveryoneandeverythinginthatroom.Itwillnot,asmanywouldconclude,overheatthatspaceandmakeituncomfortablystuffyandunbearable—unlessthemasonryheaterwasnotproperlyusedorwas

improperlydesignedforthespace.Seechapters7and8formoreonproperdesign.Intheprimarylivingspace,whichmightincludeakitchen,livingarea,dining

area,andmore,theuniquenessofradiantheatrequiressomeconsideration.Therearetwooverridingqualitiesofamasonryheatertokeepconstantlyinmind.First,asdescribedearlier,itisagatheringpoint.Second,itheatslivingspaceprimarilywithradiantheatthattravelsoverdistancetothingsandpeople.Ifyouputoneofthesequalitiestoofaroutofmind,theotherwilldominatethewaytheheaterisusedandenjoyed.Forexample,oneofmyclientsdecided,againstmyadvice,tolocatehis

heaterinacornerformedbyanL-shapedstaircase.Althoughthislocationisstillintheprimarylivingspace(whichincludesthekitchen,diningarea,andlivingroom),itisremovedfromthelivingroomandontheedgeofthekitchen.Theownerisgenerallyhappywiththeperformanceofthemasonryheatertoheattheprimarylivingspace;however,whenhehasguestsinthewinter,theygravitateandstayclosetotheheaterratherthanstrayingintothelivingroom.Althoughhislivingroomislargeandsetuptoaccommodatemany,hisguestsremainonthefringeofbothkitchenandlivingroom.

FIGURE5.10.Thoughthismasonryheateriscentraltotheprimarylivingspace,awallseparatesitfromthediningarea.Makingthebenchtotherightheatedwouldhaveamelioratedthis.Instead,itismainlysittingareawithstoragebelow.Noticealotofprovisionforfirewoodandtheuseofsoapstonetilestocarrythecoloroftheheaterintoitsaccessories.PhotocourtesyofTulikiviCorporation.

Otherclientshaveplacedthemasonryheaterinthecenterofalivingroomarea,buthaveseparateditfromtheotherfrequent-useareasbywallsorstaircases.Thustheheaterisperfectasthegatheringpoint,butdoesmuchlesstocontributegentleradiantheattootherpartsoftheprimarylivingarea.Mostpeoplewhoareinvestinginthisdegreeofcomfortwillwanttoexperienceitoveralloftheprimarylivingspaceandlocatetheheaterinthebestgatheringplaceoftheprimarylivingarea.

TheCentralHearthintheOpenFloorPlan

Followingthe“chimneyrules”andpayingattentiontotheactualfunctionofthe

heaterservetoputthehearth—theplaceforafire—initsrightfullocation.Thereisnomoreappropriateplaceforamasonryheaterthanthecenterofactivityandenjoymentofahome.Thesacredfirehasalwaysbeenthethingaroundwhichhumanlifeunfolds.Thenaturalbenefitsoftheheaterarebeggingtobemaximizedbysuchalocation.Therequirementsforgoodchimneyoperationlikewiseservetoforcetheissue,dictatingthatthemasonryheaterbesomewhereclosetothecenterofthehome.Gettingthemaximumfunctionfromachimneyandcombiningitwiththemaximumcomfortpossibilitiespresentedbytheradiantheat—agatheringpointandradiantcomfortthroughouttheprimarylivingspace—demandsthatamasonryheaterbelocatedcentrally.Putsimply,thesinglemosteffectivewaytogetthemaximumenjoymentfrom

amasonryheateristohaveitcentrallylocatedinthemainlivingareaofthehomewithnowallspresenttoimpedeitswavesofheat.Inacentrallocation,theexhaustisvirtuallyguaranteedalwaystogoupthechimney,peoplecaneasilygatheraround,andradiantheatcanreadilyfinditswayintoeverycornerofeverypartoftheprimarylivingspace.Theprimarylivingspaceisnotprivatespacetowhichpeoplegotoseek

solitude.Itisalwaysthehubofactivity.Walls,thus,areunnecessaryobstructions,notonlytothegentleradiantheat,butalsotoincludingeveryone.Withoutwalls,someonecookinginthekitchencanstilleffectivelycommunicatewithsomeoneinthelivingroom.Asmile,agesture,afire,andcomfortableheatallcombineandmixinapleasant,unrestrictedway.Withoutwalls,furnitureplacement,area-specificfunctions,andthemasonryheateritselfdefinespaces.Withoutwalls,guestsandfamilymembersalikecaneasilymingle,explore,andfindapersonalspotwhilestillbeinginvolvedinthefestivities.Timber-framehomes,loghomes,geodesicdomes,andhousesutilizingfree-

spantrussesallencourageopenfloorplans.Evenconventionallyframedhomes,withcarefuldesign,cancertainlybebuilttoprovideoptimumconditionsforagatheringareaandradiantheat.Anopen,unrestrictedfloorplansurroundingthemasonryheaterwillforeverallowresidentstofullyenjoyeverythingtheheaterhastooffer.

FIGURE5.11.Thisfinelysculptedstuccoheaterhasnowallsaroundittohinderitsheatingability.Asimplebutcurvedwoodenbenchfollowsthecontoursoftheheater,anddelicatetileaccentsaddjustalittlecolor.Everycurvedsurfaceherewillradiateheatlikethesun.PhotocourtesyofBiofire,Inc.

LocationsinaRetrofitorClosedFloorPlan

Althoughthereisnochangetotheparametersyou’dusetofindagoodmasonryheaterlocationinanexistinghouse,thereareadditionalchallengesthatcanthreatentheviabilityofsuchaproject.Obviously,thisislesstrueifthemasonryheaterwillbepartofasubstantialremodelingprojectinwhichevenstructuralchangestothehomemaytakeplace.Inarenovationinwhichwallsmightberemovedandthefloorplancompletelyredone,locatingamasonryheaterrequiresnomoreconsiderationsthanalreadymentioned.Thosewhoareaddingaheaterwithoutothermajorchanges,however,willhavemoretothinkabout.Formanyolderhomeswithfireplaces,itseemslikeusingtheexisting

fireplacelocation—anexistingchimney—isasensible,no-braineroptionforthemasonryheater.Unfortunately,somanysuchhomeshavetheexistingfireplacethroughanoutsidewall.Somewillevenhaveadouble-whammyviolationofthe“chimneyrules”—theexistingchimneyisnotonlyoutsidethewarmenvelopeofthehousebutalsoinasingle-storyadditiontoanotherwisetwo-storyhouse.

Thisscenarioisavirtualguaranteeofpoorchimneyperformanceandthereforepoormasonryheaterperformance.Itispossibletorelineanexistingchimneythatisotherwiseanoutdoor,cold

chimney.Iftheoutdoorlocationistheonlyproblem(theonlyviolationofthechimneyrules),reliningtheoldchimneywithaninsulatedlinermayleadtosatisfactoryresults.Itisstillquestionable,however,andisworthcarefulconsiderationbeforemovingaheadwithplansforalifelong,heirloommasonryheaterinstallation.Theinputofaprofessionalmasonryheaterdesignerisinvaluableundertheseconditions.Again,considerthefunctionalrequirementsofmasonryheatasdescribedearlier,aswellasthepracticalityofthelocationasagatheringpoint.Suchcompromisedscenariosareoftenno-winsituations;youmaybebetter

offinsteadabandoningfireplacesandchimneysthatsoflagrantlyviolatethemostbasicrulesforgoodperformance.Thinkofthatwallwhereanoldineffectivefireplacewassitedasanopportunitytoaddfurnitureonceyouclosethefireplacepermanently.Itisworthwhiletothendoacarefulanalysisoftheprimarylivingspacenearthecenterlineofthehouseandcompletelywithintheheatedregionsofthehouse.Abetterlocationexistssomewhereinthatlivingspace.

Single-StoryRetrofits

Inmostsingle-storyhomes,aretrofitisnotallthatchallenging.Themasonryheaterwilllikelydisplaceorchangecurrentfurniturearrangements.Theexistingfloorplanalsomaynotbe“open”atall.Itgoeswithoutsayingthataretrofitintoanexistinghomewithadesireforminimalremodelingwillrarelyresultintheidealmasonryheatersituation.ThefactisthatmosthomesintheUnitedStateswerenotandarenotdesignedaroundafunctionalcentralhearth.Compromisewillhavetobemade,butmostofthesameconsiderationsapply.Goodchimneyfunctionandalocationinthemost-usedareaofthehomewillstillprovidegreatenjoyment.The“closed”floorplan—whereeveryroomisdistinctlyseparatedbywalls

fromeveryotherroom—necessarilydecreasesthedegreetowhichradiantheatcanbeenjoyedthroughoutthehome.Thisdoesn’tmeanamasonryheatermustberejected,butitmayalterthestrategyyouusetoheatthelivingspace.Radiantheatsimplydoesnotpenetratewalls(thoughitcanwarmthemthroughandthrough).Especiallyinsmallerhouses,orhousesinwhichtheprimarylivingspacereallyisjustoneroom,theclosedfloorplancanactuallymagnifythe

enjoymentofthemasonryheaterinthatspace.Asalways,it’scriticalto“knowthyself”andplantheheaterforthewayyourfamilylives.Sizingaheatertothespaceisdiscussedindetailinchapter7.Sincethereisnoupperfloor,chimneyplacementisn’tmuchofanissue;it

willnotaffectotherlivingspacesofthehouse.Infact,onceasuitablelocationisdetermined,theonlychallengingaspectinasingle-storyhomeisthesupportstructureforthemasonryheater.Seechapter9formoreonthistopic.

MultistoryRetrofitsAsinasingle-storyexistinghome,thesupportstructureandtheproperplacementoftheheaterinthespaceneedscarefulthought.Themultistoryhome,however,hastheadditionalcomplicationofoneormorefloorsoflivingspaceabovethelocationofthemasonryheater,unless,ofcourse,you’regoingtoplacetheheateritselfontheuppermostfloor.(Inthiscase,supportstructurethroughlivingspacebelowtheheaterwillneedalotofplanning.)FIGURE5.12.Thechimneyofthissoapstoneheatergoesthroughtothesecondfloor.Carefulplanningkeepsitoutofthewayupstairs.Thisone-of-a-kindsoapstonecreationisshowninfigure1.10aswell.PhotocourtesyofWarmStoneFireplacesandDesigns;photocopyrightMikelCoveyPhotography.

Thefirststepistolocateoneormorereasonablesitesfortheheaterandchimney.Youcantemporarilymarkthefloorwithapotentialchimneylocation.Theeventualchimneysizeisoflittleconsequenceatfirst;rightnowyou’rejust

determiningacenterpoint.Thentakecarefulmeasurementsfromreliablereferenceobjects.Exteriorwallsarebestasreferencesaslongasthewallsremaininthesameplaneallthewaythroughtheotherupperstories(thisisnotthecaseinsomedesignswithcantileveredsecondfloors).Forexample,iftheproposedchimneycenterpointonthemainlevelis12feet

fromthesouthwalland15feetfromthewestwall,youcangotothenextfloorlevelandmakethesamemeasurementstolocatewherethechimneywouldbe.(Besureyoutakethosemeasurementswiththemeasuringtapeperpendiculartothereferencewall.)Ifadditionalobstaclesexistupstairs,likeinteriorwalls,thethicknessofthatwallmustbetakenintoaccountasthemeasuringproceeds.Mostinteriorwallsofconventionalhomesare4½inchesthick.Thus,youmaymeasure10feetwithinabedroom,add4½inchesforthethicknessoftheinteriorwall,thenmeasureanother1footand7½inchesoutsidethatwalltogetthefull12-footmeasurement.Thistypeofmeasurementwillrevealwherethechimneywouldpassthrough

thesecondfloorgiventhechosenlocationbelow.Ifthelocationfallssquarelyinthemiddleofahallway,forexample,it’sobviouslyunsound.Ifitfallsinacloset,thecornerofaroom,orreasonablyclosetooneoftheserelativelyout-of-the-waylocations,agoodsolutiontochimneyplacementmaybeathand.It’simportanttonoteherethatmasonryheaters,ingeneral,areveryversatileinhowtheycanconnecttoachimney.Iftheproposedchimneylocationdownstairswouldbringthechimneycenterpointreasonablyclosetoausablespaceupstairs,itcouldverywellbethataminormovementofthechimneyorthemasonryheaterorbothwillbringthechimneysquarelythroughaplacethatdoesnotadverselyaffectlivingspaceontheupperfloor.Itisunderstoodherethatasyou’remakingtheseinitialinvestigations,you

maynotreallyknowhowbigthechimneyforthemasonryheaterneedstobe.Youalsomaynotknowwhetheritwillevenbeametalflueofsomekindoramasonrychimney.Inmostcases,amasonrychimneywillbethetypethatwilltakeupthemosttotalspace.Evensomeofthelargestmasonryheaterscommonlyusedinhomesrequirenomorethanan8-by-12-inchclay-linedmasonrychimneythathasoutsidemeasurementsapproaching17by21inches.Youcanusethissizeasaguideforestimatinghowthechimneywillfitthroughthesecond-floorspace.Ifthecenter-pointmeasurement,forexample,was8inchesfromonewalland10inchesfromtheother(atthecornerofabedroom,perhaps),aslightadjustmentinactualplacementcouldhavethefluefittingrightintothatcorneroftheroom.

Ifyou’reuncomfortablewithdoingthissortofinitialstudy,consultwithamasonryheaterprofessional,whowillbemoreconfidentaboutwhatcanbedone,whatsizechimneymightbeused,andotherdetailsaboutapotentialinstallation.I’veoutlinedtheprocedureheretohelpyoudiscoverforyourselftheviabilityoftheproject,perhapsbeforeyouhireaprofessionalforamorecompleteanalysis.Somepeoplewill,however,insistthereisnowaytomakeamasonryheaterandchimneyworkinsidetheirhomes.Theymaybesurprisedtofindthatanexperiencedeyecansometimesfindagoodlocationthatsatisfiesmostdesignparametersandrunsrightthroughthecenterofthehouse.Ionceretrofittedalargemasonrychimneyintothemiddleofanexistinghome,findingapaththatsuccessfullytraveledthroughtwoadditionalfloorsoflivingspace.Ididthiswithoutalteringwalllocationsortakingthechimneyrightthroughthemiddleofprimeactivityspace.

LocationReduxLikeahigh-performancesportscar,amasonryheaterisnotmeanttobehiddenawayinacloset,basement,orotherrarelyvisitedspace.Byidentifyingtheprimarylivingspace,youlikewiseidentifythebestgeneralareatolocatethishigh-performanceheatingappliance.Byfurtherfollowingthebestrulesformaximumchimneyperformance,youassurethatamasonryheaterperformsatitsbestandneverasphyxiatesresidentswhenbeingfired.Thesame“chimneyrules”furtherdefinehowtolocatethemasonryheaterintheprimarylivingspace.Similarly,understandingtheroleoftheheaterasagatheringpointorcenterofattention,aswellasitsvastheatingpotential,refinesthesearchforthebestfinallocation.Retrofitsareanevengreaterchallengebecausealltheusualconsiderations

shouldbefollowed,yetyoumustalsocompensateforexistingconditionsthatprobablyaren’tidealformasonryheaters.Nevertheless,retrofitsarecommonandcanbesuccessfulifyoutakecaretofindagoodlocation.Inthefinalanalysis,thebestsiteforamasonryheaterisalmostalwaysasa

centralheartharoundwhichactivitywillflourish.Wheneverpossible,thiscentrallocationalsooffersopenspacearounditsothatsoothing,placidradiantheatcanbeexperiencedthroughouttheprimarylivingspace.

FIGURE6.1.Thisheaterfeaturesgraniteandmarblestoneslaidasamosaic,creatingartworkwithintheartwork.Stuccosculptsaswirlaroundthechimneyasitrisestotheceiling.Asimpleblackdoorreinforcesthatthebeautyhereisthestove,regardlessofwhetherafireisburning.PhotocourtesyofStuartDavies.

CHAPTERSIX

DesignOptions

Givenwhatwehavelearnedsofar,itisclearthatmasonryheatersarenot,inthecommonuseoftheterm,fireplaces.Masonryheatersneedtobeclassifieddifferently.Thewordfireplaceconjuresdefinitestereotypicalvisionsandexpectations.FormostofusintheUnitedStates,forexample,itimmediatelytriggersapictureofafireburninginalargerectangularopening—oftenaround3feetwideandacoupleoffeethigh—withsomekindofmantelabove.Italsoconjuresthoughtsaboutunpleasantfeatures,mostofwhichdon’texistwithaproperlydesignedmasonryheater:Slow,smolderingfires,frequentaddingofmorewood,thesmellofunburnedwood,andsootandashinthehouseallcoalescearoundvisionsofa“fireplace.”Amasonryheaterwillneverbeafireplace,iftheaboveisanaccurate

depictionofone.Forpurposesofdiscussion,thetermtraditionalfireplacereferstothisoldideaofanopenfireboxwithalargeopeningandcharacteristicsurroundsandmantel.Atraditionalfireplaceisnothingbutalargefireboxwithaflueopeningdirectlyaboveit.Bydefinition,amasonryheaterisnotatraditionalfireplace.Inreality,thereareveryfewsimilaritiesbetweenmasonryheatersand

traditionalfireplaces.Onesimilarityisthatbothhaveahearth—literally,theplaceonwhichtobuildafire—andfireboxasacontainerforthefire.Second,both(traditionally)arebuiltwithmasonrymaterialsofsomekind,likebricks,stone,andmortar.Intoday’sworld,eventhatisbecomingrarer;commonfireplacesarenowbuiltwiththetraditionalfireplacelookbutametalfireboxandasurroundofcommonbuildingmaterialslikewoodframinganddrywall.Tosaytheyarevirtuallythesameislikesayingaviolinistandanorchestraarevirtuallythesamethingbecausetheybothplaymusic.Theviolinistmaybeverytalentedandplaybeautifulsolos,butshewillneverbeabletoaccomplish,onherown,whattheentireorchestradoestogether.Traditionalfireplacesandmasonryheaterseachcontainafire,butonlythemasonryheateroffersasymphonyoffeaturesandbenefitsinadditiontothesoloenjoymentofafire.

MeetingExpectations

WhenpeopleinNorthAmericadecidetheywantafireplaceintheirhome,theygenerallyhaveinmindthetraditionalfireplace.Thisismerelybecausethisiswhattheyhavealwaysseen.Itmaybewhattheyhaveexperiencedthroughoutchildhoodandwithfriendsandneighbors.Historicalbuildingshavethetraditionalfireplace,andthetraditionalfireplaceappearsintextsdocumentingthesettlingofAmerica.Theconceptofamasonryheaterhassimplynevercrossedtheirpaths.Untilyoutakethetimetolearnaboutit,amasonryheaterseemslikean

inadequatefireplace.Whywouldanyonewantamasonryheater?Itdoesn’thavethefeaturethatwemostexpectfromafireplace—abig,openfireboxforfireviewing.It’sbulkyandtakesupfloorspace.Itisnothinglikewhatyou’reaccustomedto.It’stimetoforgenewexpectations.Ratherthanexpectingaparticular

appearance,youshouldbeexpectingversatilityandperformance.Todayautomobiles,forexample,comeineveryshape,size,andcategory.Fewwouldrelishthethoughtofahorse-drawncarriagetogetthemtotheafternoonmeetingfortymilesaway.Peoplehaverealizedthefreedomoftransportationofferedbyautos.Theycanlikewiseexperiencethefreedomoffireandwarmthdivorcedfromanoutdated,inefficienttraditionalfireplacedesign.

FIGURE6.2.Abrick,Finnish-stylemasonryheateroftenhasthestandardfireplacelookthatmanyhomeownersdesire.Noticethedeepbrickraisedhearthandtheornatebrickworkandarcharoundasquaredoor,givingtheappearanceofalargeropening.PhotocourtesyofMaineWoodHeatCompany.

Thereare,infact,somemasonryheatersthatroughlymimicwhattypicalNorthAmericancitizenspicturetobea“fireplace.”MostnotableistheFinnish-stylecontraflowmasonryheater.Althoughitstilldoesnothavethelargeopenfireboxofatraditionalfireplace,itdoeshavea(usually)symmetricaldesignthatpeoplecanrecognizeasfireplace-ish.Frequentlytheseheaterswillhavemantelscenteredabovetheloadingdoorandwillbefacedincommonbrickornaturalstone.Ifsuchaheaterisbuiltaspartofandthroughawallseparatingtwospaces,itcanfurthertheconventionalfireplacelook.Theserecognizableaspectscanbridgethechasmbetweentraditionalfireplacesandmasonryheatersforthosewhojustcannotletgoofthefireplaceideaandexpectacertain“fireplace”look.

NewPossibilities

Ifyoucangiveupyourexpectationsforwhataplaceforfiremustbe,masonryheatersareabsolutelythemostexcitinghearthproductsinexistence.Inaveryrealsense,ifyourmindcanimagineaheaterdesign,anditdoesn’tdefythelawsofphysics,itcanbebuiltasamasonryheater;itcanbeatrulyuniqueplaceforfirethatwillalwaysbewarm.Masonryheaterscanbeandhavebeenround,square,oblong,cylindrical,free-form,short,tall,multitiered,domed,arched,asymmetrical,andmore.Forexample,manytraditionalSwedishkakelugnsaretallcylinders,whileAustriansandGermanshaveoftenembracedkachelofenswithnosymmetryatall.Thefactthatstuccocansmoothlycoveranyshapedsurfacemeansafree-flowingorganicformcanbeused.FIGURE6.3.Thesymmetryofamassofstonewithacenteredfireboxagainstagreatroomwalllooksmuchlikeatraditionalfireplace.Well-executedstoneworkheretaperstoachimneythatexitsrightthroughtheridge.Noticethemassivestoneusedasamantel.PhotocourtesyofTemp-CastEnviroheat.

FIGURE6.4.Asimpleasymmetricalheaterdesign.Herethesmooth,honedsoapstoneofthelowerpartoftheheaterseguesartfullyintosplit-facedstoneatthetop.Woodstorageoffsettotheleftcompletestheresistancetosymmetry.PhotocourtesyofTulikiviCorporation.

APlacetoStart

Designstartswiththethreemajordesignaspectsofamasonryheater.(Thereisafourthaspect—thesupportstructure—butwewon’tconsideritrightnow,becauseitisdictatedinlargemeasurebythedesignofthemassabove.)Thesethreemajordesignaspectsarethefirebox,theflues(oftencalledheat-exchangechannels),andthechimney.Ofthese,thefireboxandflues,together,trulyarethemasonryheater,whilethechimneyisanoptionalelementintheoveralldesign.BythisIdon’tmeanthatyoucanexcludeachimney;everymasonryheaterneedstobeconnectedtoachimney.Rather,notallmasonryheatersneedtoincorporatethechimneyintotheoverallappearance.Sometimesthechimneywillbeavisible,commandingdesignaspectasittowersthroughahomeand

exitsacathedralceiling.Othertimesitwillbecompletelyhiddenfromview.Themasonryheateritselfconsistsofthefireboxandwhatevermasscontainstheflues,whicharetheprimaryaestheticaspectsoftheheater.Theyareconnectedtotheoft-invisiblechimney.

FIGURE6.5.Thetallcylindricalstyleofatraditionalkakelugn.Notetheintricatebraidsandtexturescastintothetile,especiallyatthetop.PhotocourtesyofNewEnglandHearthandSoapstone.

Whilethechimneyitselfmaynotbeamajordesignelement,itisthecrucialstartingpointfortherestofthedesign.Inmanycases,thechimneyis,indeed,completelyhiddeninwallsandchasesuntilitreachestheatticand/orrooftofinallyexitthehouse.Yetitisvitallynecessaryandneedstobelocatedproperlyinthehomeforproperfunctioning,asdescribedinchapter5.Oncelocated,thechimneyisthefirstparameterofdesignaroundwhichtowork.Onewayoranother,thedesignhastogetexhaustfromthefirebox,throughtheflues,tothechimney.

FIGURE6.6.Free-formshapescanbemadewiththeuseofstucco.Delicatesplashesofcolordotthisheater,whichalmostlookslikeicecreaminacone.Nichesandcontinuouschangesinsizeaddyetmoreinterest.PhotocourtesyofBiofire,Inc.

ChimneyHigh,ChimneyLow;ChimneyHere,ChimneyThereThoughthechimneyitselfisentirelyvertical,withamasonryheaterthereis

nodefinitestartingpointforit.Thechimneystartingpoint,theplaceatwhichthemasonryheaterconnectstothechimney,ishighlyvariable.Amasonryheatercanattachtothechimneyhigh—perhapsclosetothe8-footceilingofaconventionalhome—oritcanconnectlow.Manyheaterswillhaveanexittoachimneyclosetofloorlevel.Everylocationinbetweenthesealternativesispossibleaswell.Theplaceatwhichtheheaterisattachedtothechimneywillbedeterminedbytherestofthedesignatthesametimethattherestofthedesignispartiallydependentonthephysical(floorplan)locationofthechimney.Manywillbeconfusedbytheattentionplacedonchimneylocation.Itis

difficultforthosenewtomasonryheaterstoletgooftheideathatthechimneyandthe“fireplace”arethesamething.Thetraditionalfireplaceis,really,justachimneywithalargespaceatitsbaseinwhichtobuildafire.Thechimneyforamasonryheaterisjustachimney—justtheescapehatchforexhaust.Itnolongerdictatesthelocationofthefireboxasitdoesinatraditionalfireplace.Thechimneycanbesomewhereabovethefirebox,nexttothefirebox,behindthefirebox,ormanyfeetawayfromthefirebox.Presumably,thechimneyhasbeenlocatedusingthechimneyrulesfromchapter5.Ifso,thechimneyhasasetlocation.Theremainingdesignmustalwaysworktowardlinkingtothatfixedlocation.Thebeautyandversatilityofmasonryheatersisthatthereisnearlyan

infiniterangeofwaystogetfromthefireboxlocationtothechimney.Itisthereforeclearthatthemasonryheateristhemostversatilewood-burningapplianceeverconceived.

FIGURE6.8.Youmightthinktheheaterpicturedherehasnochimney,becausethefluehasbeenartfullyhiddeninthewallbehind.ThisisoneofTulikivi’snewest,moremoderndesignsfeaturinganewfireboxdesign(seechapter8)andsootdoorshiddeninsidetheashdraweraccessareabelowthefirebox.Thismakesforclean,unbrokenlines.PhotocourtesyofTulikiviCorporation.FIGURE6.7.Herethemassivechimneystructureisacommandingaspectoftheinteriorarchitecture.Thisenormousstructurewillallbevisibleinthislargespacewithhighceilings.Thebrickiscomplementedbymassivegranitebeamsandtrimpieces.Thebeamsspanfromonecolumntothenextabovetheheater.Oneofthecolumnscontainstheactualchimneyflue.PhotocourtesyofMaineWoodHeatCompany.

Asinglemasonryheaterrequiresasinglechimneystructure—andusuallyasmallerstructure,incrosssection,thanisrequiredforanopenfireplace.(Thechimneysizeinopenfireplacesisdictatedbythesizeofthefireboxopening,whichisusuallyquitelarge.)Inahomewithtallcathedralceilings,asingle-fluechimneycanhaveaskyscraperlooktoitbecauseitisverytall,butverysmall.Thosewhowantanexposedchimneystructure,foraestheticreasons,maywanttoconsiderifthereisawaytoincorporateanotherflueintothestructure.Exhaustfromagaswaterheater,abackupfurnace,orevenaventforarangehoodcanbedirectedintoasecondorthirdflueinonechimneystructure.Youcanalsoconsiderthepossibilitythatonedayyoumaywanttoaddanothermasonryheater(inabasementlivingspaceoranupperlevel),andsimplysupply

aflueforthisfutureadditionattheoutset.Theadditionalflue(s)willgivethechimneywidthandbreadthtoaccompanyitsheight,therebydecreasingitspotentiallyspindlyappearance.

FIGURE6.9.Thischimneyattachestothemasonryheateratitstop.Thechimneyfortheheaterispartiallysupportedbytheunheated“leg”totheleftoftheheater.Thestuccohashorizontalinsetlinestobreakupthelarge,flatsurface.Thisphotoreinforcesthatstucco,liketile,offersunendingcolorchoices.PhotocourtesyofEnvirotechMasonryHeaters.

Iftheinstallationdoesnotinvolveexposingthechimneyatsuchheights,itcanbemorereadilyincorporatedintothedesignofthemasonryheaterandmayevenbedifficulttoidentify,atfirstglance,asachimney.Howwellitblendswiththerestoftheheaterwillinlargepartbedeterminedbytherestofthedesignandlayoutofthehouse.Somemaynotwantthechimneytoblendatallintothemass,preferringthatitbeclearlywhatitis.Otherswilloptforgivingthemasonryheaterafurniturequality;themasonryheaterbecomesanaestheticpiecethatwouldbeunachievablewithanobviouschimney.

TheSourceofPower—TheFirebox

Mosthomesareconnectedto“thegrid”—shortforthepowergrid—theinfrastructurethatenablesthedistributionofelectricityandotherenergyservicestoresidences.Insuchascenario,thehome(or,morespecifically,thoselivinginthehome)istheenduseroftheenergythatcomestothehome.Ifnaturalgasis

pipedin,itisn’texpendeduntilsomeapplianceinthehomeisignitedandburnsthegas.Ifelectricityiswiredtothehome,itisnotconsumeduntillightsareilluminated,motorsareactivated,orappliancesareswitchedon.Everyoneknows,however,thatthepowerwasnotgeneratedatthehome.Somewhere,manymilesawayperhaps,thereisapower-generatingstation.

Forexample,acoal-burningpowerplantburnsthefuelandtransformstheheatenergytoelectricity.Theelectricityisthentransmittedthroughthewiresandsubstationstotheresidence.Inthehome,theelectricityisused.Mostpeoplearetherefore,thoughperhapsunconsciouslyuntilnow,familiarwiththeconceptofgeneratingenergyinoneplaceandusingitelsewhere.Itisnoleaptounderstandthatthesourceofthepowerisonlythesource,nottheend.Inthemasonryheater,thepowersource,the“generatingplant,”isthefirebox.

Theelectricity-generatingplantusescoal,ormaybeuranium;themasonryheateruseswood.Thehotgases,then,arethevehiclethroughwhichheatgetstotherestofthemasonryheaterviatheflues.Thefluesarelikethewiresin“thegrid.”Theycarrythepower(heat)toallpartsofthemasonryheaterthesamewaywirescarryelectricitytoaneighborhood.Theheatitselfisconductedthroughthemasonrymaterialstothelivingspacejustassmallerwiresconductelectricitytoalightsocket.FIGURE6.10.Thechimneyfluecanconnecttomanymasonryheatersnearfloorlevel.Hereitconnectsatthelowerleftside.

FIGURE6.11.ThefireboxisintegralwiththemassofthisheaterbuiltusingthecorekitsoldbyEnvirotechRadiantFireplaces.PhotocourtesyofEnvirotechMasonryHeaters.

Thisanalogyservestodemonstrateandamplifythefactthatthefireboxofthemasonryheateristhepowersource,butitdoesnotdirectlydeterminetheshapeoftherestofthemass.Thefireboxis,however,responsibleforsupplyingapproximatelyhalfoftheheatoutputoftheentireheater.Itssizeandcapacitydoverydirectlydeterminehowmuchmasssitsbetweenitandthechimney.(Fireboxdesignisdiscussedingreaterdetailinchapter8.)Thefireboxcanbeintegralwiththerestofthemass,oritcanbeaseparateelementofthewholemasonryheaterdesign.Masonryheatersthathavebecomestandardized,asinthecaseofmanykit-basedheaters,oftenhavethefireboxintegraltothewholemass.Thesestandardizeddesigns,onceagain,oftenappealtothosewhoareintentonsomethingapproachingthetraditionalfireplacelook.Thosewhohavefullygraspedtheunlimitedpossibilitiesofmasonryheaterswilloften,ontheotherhand,haveafireboxstandingalmostcompletelyindependentoftheremainingmass;thetwoareconnectedonlyasneededtoprovidethepassageofexhaustintotheheat-exchange(flue)elements.Thewordfireboxseemstoimply,indeed,abox.Usuallywethinkofboxesas

beingsquareorrectangular.Theimaginationissetfree,however,whenfireboxisreplacedwithcontainer.Thefireboxis,afterall,thecontaineroffire.Itholdsthefireandpreventsthewood,coals,embers,andgasesfromgoingwhere

they’renotsupposedto.Thefreedomofcontaineristhateveryoneknowsofcontainersofallsortsofshapesandsizes.Thereareroundcontainerslikecylinders,spheres,andovals.Therearemultisidedcontainersthatareoctagonalorpentagonalinshape.Itisevenpossibletohaveacontainer—afirebox—thatisnotsymmetricalinallrespects.Andthereis,indeed,theever-practicalcubeorrectangularboxformthatmostofusexpectinourrectilinearsurroundings.Thereare,ofcourse,variousstructuralandfunctionalrequirementsthatneed

tobemettohaveaneffectivefireboxdesignforamasonryheater.Ifthegoalistocontainthefireandheat,thefireboxshapemustbeconducivetocontaining,ratherthandispersing,theheatandotherelementsofafire.Aslongasthefireboxfunctionsasacontainer,anyoftheaforementionedshapesarerealisticandpossible.Aswithanyproject,therearealsobudgetaryconsiderations.Buildinga

fireboxthatliterallyisaboxofrectangularshape,usingbricksandothermaterialsofrectangularshape,willbemorecost-effectivethan,say,tryingtobuildacylinderwithrectangularmaterials.Theeffortneededtoproperlycutandfitvirtuallyeverypiecetomakesomeoddshapesissubstantial.InEurope,wherethemasonryheaterconcepthasundergonehundredsofyearsofdevelopmentandneverfallenentirelyoutoffavor,therearespeciallyshapedmaterialsreadilyavailablethatpermitodd-shapedconstructionswithmuchlesslaborintensity.AsmasonryheatersbecomemoremainstreaminNorthAmerica,nodoubtindependentmanufacturersofspecialtypartswillfulfillthesamepurposehere.Thiswilleventuallymaketheunusualshapesmorebudget-friendly.Theresultsofliterally“outofthefirebox”thinkingcanbestunning.FIGURE6.12.Thefireboxforthisheaterisastand-aloneelementwiththemassitpowersbehindit.Handmadetilesandthecurvesofthemassbeyondthefireboxareperfectexamplesoftheendlesspossibilities.Anotherviewofthisheaterisinfigure4.2.Kachelofendesigned,built,andphotographedbyErnstKiesling,CanadianKachelofen.

FIGURE6.13.Aone-of-a-kindmasonryheaterdesignedtofitacustomer’staste,decor,andlivingspace.Thisconcepthasbeenapproved,withslightmodifications,bytheclientandwillbeconstructedofstructuraltilesforaresidenceinsouthernOhio.

FIGURE6.14.Theplanviewshowstheunusualshapespossibleinmasonryheaterdesign.

TheMassforHeatExchange—TheHeatingElements

Everypartofamasonryheater,includingthefirebox,isbuiltwithdensematerialsthatradiateheat.Ifthefireboxisincorporatedintothemassthatincludesalltheflues,thenobviouslyallofitistheprimaryheatingelement.Somewouldthereforearguethat“themass”istheentiremasonryheater.Thisistrue.Forthepurposesofdiscussion,however,themassoftheheat-exchange

areawillbeseparatedfromthefireboxpreciselytoexplainhowtheycanbeseparatedesignelements.Becauseit’spossibletolargelyseparatethethreemainelements—chimney,firebox,flues—themassismainlydefinedbythebodyoftheheaterthatcontainsalltheheat-exchangechannels(flues).Thismasscontainingthefluesisthenaprimaryheatingelementofthemasonryheater,eventhoughthemassthatincorporatesthefireboxalsoprovidesabouthalfofthegentle,radiantheat.

FIGURE6.15.Imaginelayingouta40-foot-longsquareflueontheground,thencuttingitintovariouslengths.Theresultisnumerous“boxes”containingflues.Theseboxescanthenbestackedorrecombinedtomakevariousdifferentshapesandarrangements.Thisdrawingshowsjustoneoftheinfinitewaysthesefluescanbecombinedtomakeanasymmetricheaterdesign.

Thesizeofthemassrequiredtomeettheheatinggoalsofthespacewillcertainlyinfluencethedesign;thiswillbediscussedmoreinchapter7.Here,however,theaimistodescribethefreedomandversatilityinherentinthemasonryheaterconcept.Freeingtheview,forthemoment,fromconstraintsanddictatesofsizeallowstheexplorationofallthepossibilitiesinstrictlydesignterms.Thefireboxelementandtheflueelement(s)connecttomakeawhole.Onecannotfunctionwithouttheotherandstillbeconsideredamasonryheater.Butinawell-designedmasonryheater,thebulkoftheavailablemasswillresideintheheat-exchangearea.

FIGURE6.16.Assuggestedinfigure6.15,thismasonryheaterisacombinationof“boxes”containingallthefluesinanasymmetricdesign.Addstucco,tile,somewoodforabench,andanicheforwoodstorageandyouhaveabeautifulmasonryheater.PhotocourtesyofBiofire,Inc.

Thefluesinevenasmallmasonryheatercanbequitelong.Forexample,afireboxwithafloorareaofjust1.5squarefeetmayhaveatotalfluelengthofaround40linearfeet!Ifyouimaginea40-footchimney,8inchessquare,turnedhorizontally,thepicturebecomesclear.Suchafluecouldrunthefulllengthofmanyhouses.Dividedinto3-or4-footlengths,thisfluehasadozenorsopiecesthatcanberuninvariousdirections.Therecouldbeonerectangularbox4feetlongand5feettallcontainingmorethanhalfofthosefluepieces,coupledwithtwoorthreesmallerboxeseachcontainingtwoorthreeofthosefluelengths,makingasculpturedsetofboxesconnectingthefirebox—anotherboxperhaps2feetwideand4feettall—tothechimney.Withthebasicideainplace,youcangetcreative.Supposethatsinglelarger

elementwasturnedintoaroundedshape,thefireboxisturnedintoacylinder,andtherestbecomescurvedbenches.Youmightendupwithaheaterthatlooksliketheoneinfigure6.17.Suddenlyaheaterwiththesamegeneralsizeparametershasacompletelydifferentappearancewhilemaintainingthesameheatingpotential.Oryoucouldretainalltheoriginalshapesandsimplymovethemaroundintoadifferentarrangement.Ofcourse,theseelementscouldalsosimplyberedrawnindifferentsizesandshapesbutcontainingthesamelengthofflues.Thepossibilitiesareendless,andthisisjustoneparticularsize!Alargermasonryheaterwouldrequiremorefluelengthandmoreoverallvolumeand/orsurfacearea.Thereisnoexhaustingthepotentialrangeofoptionsforagivensetofsizeparameters.

FIGURE6.17.Insteadofthinkingintermsofboxes,curvesandcylinderscanbeused.PhotocourtesyofBiofire,Inc.

AdditionalElements

Manypeoplewhoinvestinmasonryheatersrealizetheinherentopportunities.Whowouldnothaveanattractiontoawarmseatinthedeadofacoldwinter?Sincethefluesofthemasonryheatercanbepartofnearlyanyshapeandsize,anobviouschoiceistohavethemformsittingareas—benches,seats,orplatforms.Alowplatformcouldbelargeenoughtolieon;itcouldevenbeanappendageintoabedroom,makingitabed.Sinceamasonryheaterisagatheringpoint,it’sjustlogicaltoconsiderincorporatingsittingareasintothemass.Thosecominginfromthecoldwillforeverappreciateawarmplacetosit;withoutit,theyarerelegatedtostandingagainsttheheater.Seatsorbenchesdonothavetobeheated.Itisalsopossibletomakeabench

independentoftheflues,yetprovidingaplacetositandleanbackagainstthewarmbodyoftheheater.Awoodenbench,thoughnotheated,willfeelcomfortable,whereasamasonrybenchoftenfeelscoolifit’snotdirectlyheatedbytheflues.Forthisreason,woodenbenchesarealsoanattractiveoption.

FIGURE6.18.Thisentiremasonryheaterisasittingareamadewithstructuraltilesorkacheln.Thefireboxisinthefarrightofthephoto,thebox-likeshortstructurefacinganotherpartoftheroom.PhotocourtesyofNewEnglandHearthandSoapstone.

Masonryheatersprovidegentlewarmthtoahomeusingstoredsolarenergy,intheformoffirewood,toheatlivingspace.It’sabonusthatyoucanalsobakeartisanal,brick-ovenbreadwiththatsamerenewableenergy.Becauseaheaterismeanttostoreheatforsuchlongperiodsoftime,creatingandusingabakingovenisalogicalsteptowardgreaterenergyindependence.Amasonryheaterwithbakeovenisanoventhatis“alwayson”intheheatingseason.Temperaturesremainrelativelyconstantforsuchextendedperiodsthatdependablecookingofeverythingfrombreakfastporridgetostewstopizzasandbreadispossibleinabuilt-inoven.Tolearnmoreaboutbakinginamasonry

heaterbakeoven,seechapter11;alsoseethesectioninthischapteronbakingovensasstand-alonecompanionstomasonryheaters.Ifyoucanhaveawarmseat,it’snotastretchtohaveavarietyof“seats”for

otherpurposesaswell.Smallnichesorshelvesfacinganentrycanbeawarminganddryingplaceforglovesandhats.Shelvesorcompartmentsfacingthekitchencankeepfoodwarmbeforeamealorprovideaplaceforproofingbread.Asmall,secludedalcovecouldbeaplaceforapettosleep.Inthissamelineofreasoning,hookscanbeincorporatedintothemassforhangingcoats.Rodscanbesituatedoverthetopoftheheateroroveraplatformfordryingwetclothes.Smallcompartmentsorshelvescanbecreatedforshoesorboots.Apopularcompartmentinmasonryheatersisforfirewoodstorage;it’shandytohaveanalcovelargeenoughtoholdfirewoodforoneortwofireboxloadsoffuel.Thewarmthofsuchacompartmentkeepsfirewooddryandprewarmedforeasyfirestarting.

FIGURE6.19.Thisbrickheaterboastsabakeoven,shelves,nooks,aworkingsurface,andsittingareas.HeaterdesignedandbuiltbyStovemaster;photocourtesyofAlexChernov.

Thewood-storagecompartmentcanalsoincorporateawoodwaiter,whichisaspin-offfromtheveryoldideaofadumbwaiter.Today,however,awoodwaiterisoperatedwithelectricmotorsratherthanamanualpulleysystem.Itis,

essentially,anelevatorforthewoodsupplyasseeninfigure6.20.Ifwoodiseitherkeptinorbroughtintothehousethroughabasement,youcanloadaquantityintothewoodwaiter,whichwilltransportthefueluptothenextfloor,reducingboththeeffortrequiredandthepotentialmessthatsometimesaccompaniesthetransferofwoodfromoneplacetoanother.Thewoodwaitercanbelocatedrightnexttothemasonryheater,oritcanbesitedelsewhereifspaceisanissue.Youcanevenconcealitinacabinet.

Alwaysbearinmindthatadditionsorappendagestoamasonryheaterthatdonotcontaininternalfluescanactuallyimpedeheattransferandradiantheating.Forexample,alargewood-storagecavitybuiltrightnexttoaradiantwalloftheheaterwillgreatlyaffecthowmuchradiantheatyoureceivefromthatwall,justasbuildingaheateragainstawallwillreduceitsradianteffect.

FIGURE6.20.Awoodwaiterletsmotorsdotheheavyliftingwhenfuelneedstobeonthenextfloorup.|FIGURE6.21.Ahingedcoveroverthewoodwaitercanmatchthefloorsoitbecomesalmostinvisible.|FIGURE6.22.Whenthewaitermustbesomedistancefromthemasonryheater,awheeledcarteffortlesslygetswoodfromoneplacetotheotherwithnomess.PhotoscourtesyofW.B.FowlerIndustries,Inc.

HeaterCompanions

Mostpeoplewouldenjoybeingacompaniontoawarm,invitingmasonryheater,butthetypeofcompanionI’mdiscussinghereisasecondfunctioningheatertogowiththeprimarymasonryheater.Thissecondmasonryheatercouldbeabove,below,orontheothersideofawallfromtheprimaryheater.Itcouldalsobeamasonrycookstove,sometimescalledacooker.Anditcouldalsobeastand-alonemasonrybakeoven,functioningcompletelyseparatelyfromtheprimaryheater.Alltheseoptionsaredifferentiatedfromthepreviousamenitiesbythefactthattheyare,bythemselves,appliancesthatoperateseparately,yetcomplementarily,totheoriginalmasonryheater.

ASecondHeater?

Thosewhoappreciatetheuniqueradiantheatavailablefromamasonryheatermaywanttoconsiderasecondheater(ormore)intheirhouseplans.Sometimesitjustmakessensetohavemorethanonemasonryheater,especiallyinalarger,multilevelhouseorahousewithalotofareaspreadoutonasinglelevel.Thefloorplanofagivenhousemaynotbeconducivetooropenenoughforsomeimportantareastoreceivethegentlewarmthofradiantheatfromonemasonryheater.Along,narrowhome,likesomeranchstyles,willbenefitgreatlyfromradiantmasonryheatersinmorethanoneareaifyou’reintentonenergyindependenceandpenetratingradiantheatthroughout.Twoormoresmallerheatersarrangedstrategicallyinahomeprovideevengreaterheatingversatility,particularlyinpartsoftheyearwhenonlyalittleheatingisneeded,likeearlyautumnorlatespring.Theideaofacompanionheateristhat,thoughithasitsownchimneyflue,it

sharesthechimneymasswiththeprimaryheater.Itcouldverywellbeamasonryheaterjusttotheothersideofamajordividingwallofahome.Forexample,themasonryheaterfortheprimarylivingspacemaybeagainstaninteriorwallseparatingthegreatroomfromamasterbedroomsuite.Asmallroomheatercouldbesituatedinthemasterbedroomandtiedintothesamechimneymassthatservesthelargerheater.Alltheaforementioneddesignconsiderationsapplywithaddingasecond

heater.Youstillneedtofigureouthowtogettheexhaustfromthefireboxtothechimney.Theproximityofthetwoappliancescanrendersomeinterestingcreativeopportunitiesthat,again,canincorporateoptionslikeheatedsittingareas,niches,andadditional,stand-aloneheatingelements.It’sentirelypossibletohaveoneormoreheatingelementsthathavefluesfrombothappliancesrunningthroughthem.

StackedHeatersAsthenameimplies,stackedheatersarebuiltoneatoptheother;theonebelowsupportstheoneabove.Thisdesignisawaytogetallthebenefitsofradiantheatontwofloorsdistinctlyseparatefromeachother.Inaclosed-floor-plantwo-storyhouse,thesecondfloor(orafirstflooraboveabasementthathaswell-usedlivingspace)willnotbenefitatallfromtheradiantheatofamasonryheater,thoughitwillreceiveconvectionheat.Buildingoneheaterabovetheotherisonewaytogetradiantheatonbothfloorlevelsandstillmakeuseofthe

samechimneystructureorchase.Thechimney,ofcourse,wouldhavetonowcontaintwoseparateflues(seechapter9).Ifoneheaterisliterallybuiltontopofanother,thebottomheateristhe

foundationfortheupperheater.Beawarethatmasonryheatersaredesignedtoefficientlystoreandtransferheatfromtheirveryhotinteriorstothelivingspace.Thisgenerallymeansthattheheaterwallsarenotdesignedtosupportalotofweight.Inaddition,amasonryheaterissubjecttoexpansionandcontractionasitheatsandcools.Thisisonereasonit’sgenerallyunwisetomakeamasonryheaterasupportstructureforotherelementsofthehouse.Therearesomeheaterdesigns,however,particularlythosethatarebuiltfrom

premanufacturedcorekits,thataremeanttohavetwoindividual,disconnectedcomponents.Theinnerlife,orcore,isdistinctlyseparatedfromtheouterveneerbyanairgaporsomekindofthermalexpansionmaterial.Inthesedesigns,themajorityofexpansionforcesarepresentintheindependentinnerlife.Whiletheoutershell(veneer)doesgetwarm,itisn’tsubjecttoasmuchmovementasthecore.Thistypeofdesignisthereforemoresuitableasthefoundationforanotherheaterabove.

FIGURE6.23.Thissoapstoneheaterextendsthroughtheceilingintothesecondfloor.It’soneversionofatwo-storyheater.|FIGURE6.24.Hereisthesecond-floorportionoftheheatershowninfigure6.23.Havingtheheaterextendintoanotherlevelofthehouseprovidesradiantheattothatupperlevel.Inthiscaseit’sasimpleseat,thoughitcouldhavebeendesignedtobelargerortallerwithmoreheatingcapacity.PhotocourtesyofNewEnglandHearthandSoapstone.

Thisisnotmeanttosuggestthateverysuchveneerisadequatetoserveasafoundationforanotherstructure.Ifyou’recontemplatingthisarrangement,talkwithaqualifiedstructuralengineeraboutthepossibilities.Everyhomeisdifferent.Ceilingheightsaredifferent,seismicrequirementsaredifferent,materialsaredifferent,andloadsaredifferentfromoneprojecttothenext.Isimplycan’taddressalloftheseconsiderationsadequatelyinthistext.Similarinnature,buthavinglesscomplexityfromthestructuralengineering

standpoint,istheideaofatwo-storymasonryheater.Sincesuchastructureonlyneedstosupportitself,onlyitsparticularself-imposedstresses(alongwith,again,anyseismicconcerns)needtobetakenintoconsiderationinitsdesign.Thetwo-storyheaterotherwiseaccomplishesthesamegoalsasthestackedheaters.Havingheatingmassontwolevelsofthehouseassuresradiantheatineach.Unlikestackedheaters,asingle,tallmasonryheaterhasonlyonefirebox(thoughit,too,couldbedesignedwithmorethanone).Thismeansthat,likeanysinglemasonryheater,itneedstobefiredonlyonceortwiceeachday.Thefireboxwouldbeonthelowerlevel;woodonlyneedstobesuppliedatthatlevel.Inotherwords,thetwo-storyheaterincorporatesfluesthattravelfromthe

fireboxthroughmassonthefirstlevelandthesecondlevelbeforeemptyingintoachimney.You’veseenastretchlimo;inessence,atwo-storyheaterisastretchedversionofasingle-storyheater.Insummary,thismeansthatheatingwithatwo-storyheaterissomewhat

simplerthanheatingwithtwo.Theflipsideisthattheideaoftwoseparateheatersactuallylendsmoreversatilityinhowthelivingspaceisheated.Likeanyothermasonryheater,thetwo-storyheatercanbecustom-designedforthespacejustassurelyastwocouldbe.

Cookstoves(Cookers)

Anotherstand-alonemasonryheatercompanionisamasonrycookstove.Thesecookstovesworkonthesameprincipleasmasonryheatersthemselves—withoneimportantdifference:Themetal(usuallycast-iron)cooktopisoneoftheprimaryheat-transfermaterials.Usuallytheexhaustoftherelativelysmallfireboxloadofwoodcontactsthecookingsurfacesfirst,thencontinuesthroughthemasonrymass.Inthisway,highsurfacetemperaturesareachievedonthecookingsurfacesandresidualheatnotcapturedthereistransferredtothemasonrymassofthestovestructure.Themasonrycookstove,then,issimplyasmallmasonryheaterwithaspecializedfunction—cooking.

Obtainingcompletecookingandheatingcapabilitieswithamasonryheatercomplexprovidesthepotentialfornearlycompleteenergyindependenceformanypeople.Justahundredyearsago,cookingandheatingwithwoodwascommonplaceinNorthAmerica.Withtheintroductionoftheheat-retainingcapabilitiesofmasonryheaters,doingsotodayentailsfarlessworkthanitdidinthosedays.Italsoinvolvesmuchmorecomfortableheat.Acookerwithbakingovencombinedwithamasonryheater(alsowithoptionalbakingchamber)givesownersfreedomfromfossilfuelsfortwoeverydayneeds.

FIGURE6.25.Amasonryheatercomplex.Heater,oven,andattachedcookstovemakegreatcompanionsandprovideheatingandcookingself-sufficiency.Notethewood-storageareaandsoapstoneheatedbenchtopsandtrim.PhotocourtesyofMaineWoodHeatCompany.

Acookercanbebuiltinavarietyofways.Amasonrycookstovemayprimarilybeamasonrystructurewithappropriateaccommodationmadeforaforged-metalovencomponent,therequiredfirebox,cleanoutdoors,and,ofcourse,themetalcooktopitself.Alternatively,theentireassembly(savethecooktop),includinganoven,couldbebuiltentirelywithmasonry—asisthecasewithmostheaters.Also,anappliancelikethismayhavenoovenatall;itmaybedesignedstrictlyforacooktop.Ametalovenobtainsheatfromacombinationoftheimmediateexhaustfrom

anexistingfire,andthestoredheatinthemasonry,thoughthelatterwillbemostimportantforlong-termcookingoverthecourseofaday.Indesignsincorporatinganall-masonryovenchamber,theovenitselfisanotherfirebox.Thiscooktop-and-ovencombinationunitthenmayrequiretwochimneyflues;oneisforthecooktopfireboxandtheotherforfiringtheoven.It’salsopossibletohaveanapplianceequippedwithanovenandacooktopusingonlyoneflue,thoughoftenthesedesignswillrequireyoutochoosewhichfireboxtouseatanygiventime;youcan’tusebothatthesametimeononechimneyflue.

FIGURE6.26.Thiscookstovefeaturesametaloven.Theoveniswarmedbythemassofbricks,notbyafiredirectlyintheovenchamber.PhotocourtesyofEnvirotechMasonryHeaters.

FIGURE6.27.Acookstovewithnobakingoption.Theupperdoorisforthefirebox;thesmallerlowerone,forashremoval.PhotocourtesyofTulikiviCorporation.

Whenacookerapplianceismatedwithamasonryheater,itcanofcoursebetreatedthesameasyoumaytreatanyothersecondmasonryheaterjoinedwiththefirst.Amajordifferenceis,ofcourse,thatacookerhasadditionallimitationsonitsdesign.Thefactthatametalheat-transfersurfaceisinvolvedreducesthetotallengthoffluesthatcanservicetheappliance.Metalcooktopsquicklyabsorbheatfromafire,drasticallycoolingtheexhaustimmediately.Therefore,thereisnotasmuchresidualheatremainingthatcanberoutedthroughlongflues.Thedesignmustbesuretogettheexhausttothechimneywithsufficientheatforgoodchimneydraft.Thisconsiderationmeansthatamenitieslikeheatedbenches,platforms,orotherheatingelementsaregreatlyrestrictedforcookstoves,justastheywouldbeforquitesmallmasonryheatersingeneral.

FIGURE6.28.Acookstove/bakeovencombinationinwhichtheovenisamasonrycombustionchamber.PhotocourtesyofTulikiviCorporation.

BakingOvens

Bakeovenchambersaregenerallypopularoptionsforamasonryheater.However,noteveryonewillwantabakingoventhatisalwaystiedtoamasonryheaterusedforheatinglivingspace.Oncethemasonryheaterisidledforwarmermonths,thebakingovenbecomesoflittlevalue.Fewwillwanttofireamasonryheaterinwarm(orhot)weatherjusttobakesomebread.Formanyprospectivehomeowners,inmilderclimates,thiscouldmeansixmonthsoftheyearinwhichbakinginthebrickovenwouldnotbeareasonableoption.Thosewhowanttobakethroughouttheyearwillwantotherchoices.Thereare,ofcourse,masonrybakeovensthatdoubleasprimaryheaters.In

otherwords,thesearemasonryheatersthathaveabakeovenchamberastheprimaryfirebox.Woodburnedinthebakingchamberproducestheheattowarmthemassoftheheaterforwarmingthelivingspace.Atthesametime,thebakeovenchamberischargedwithalotofheatforlong-termcookingandbaking.(Seechapter11forphotosandmoreinformationaboutthese.)This,ofcourse,isnodifferentineffectfromhavingamasonryheaterwithaprimaryfireboxandaccessorybakeoven.Eitherway,theovenisfunctionalonlywhenyouintendtoheatyourlivingspacewiththeheater.

FIGURE6.29.Thebakeoven,insidethelowarcheddoor,isstrictlyforbakingandnotforheating.PhotocourtesyofMaineWoodHeatCompany.

Amoreattractivechoice,forthosewhowantthebenefitsofbrick-ovenbakingallyearround,istohaveabakingoventhatisonlyacookingapplianceanddoesnotaimtoheatlivingspace(seefigure6.29).Suchanovenretainsheatinitsmassivestructure,butisinsulatedtopreventtheheatfrommigratingoutofthemass.Inasense,itisamasonryheateroperatinginreverse:Thewoodfirewarmsallthemasonrymaterials;thestoredheatisusedtopromotelong-term,continuousheatingoftheovenchamber.Everyeffortismadetolimittheamountofheatescapingtotheexteriorofthestructure—intothelivingspace.Usingabrickovenlikethis,youcanbakeallsummerlongwithwoodfuelwithoutundulywarmingtheinsideofthehouse.Abakingovenisatremendousadditiontoamasonryheater.Usingstored

solarenergyintheformofwood,storingitagainasheatinamassofmasonry,thenmakinguseofthatheatoverextendedperiodsforheatingandcookingistheultimatestatementoffreedom,independence,andwiseuseofresources.Thereisnomoreimmediatewayofcreatingsecurityinahomethantoprovideawaytoheatandcookthatdoesn’trequireconstantfire-tendinganduseslocallyharvestedfuel.

MaterialOptions

Theversatilityofthedesignofmasonryheatersismatchedbythetypesofmaterialsthatcanbeusedintheirconstruction.Masonrymaterialsusedforthevisible,aestheticlookoftheheaterrangefromthesimple,likeplainstucco,throughvariousbricks,coloredrefractoryconcrete,anyspeciesofstone,andstructuraltile.Inaddition,thesematerialscanandhavebeencombinedininnumerableways.Havingsaidthis,Ishouldnotethatallmasonrymaterialsarenotcreatedequal.Therearedefiniteadvantagesanddisadvantagestosomeoverothers.Amasonryheaterisamultigenerational,heirloom-qualityadditiontoanyhome.Considerallthepossibilitieswithultimatecare,foritwillbearoundvirtuallyforever.Drapesgetchangedtwiceperyear,carpeteverytenyears.Aroofmightbereplacedintwentyyears.Amasonryheater?It’smeanttobethereforalifetime(orlonger).

ThermalBehaviorofVeneerMasonry

Amasonryheaterisanentirelyfunctionalheater.Virtuallyeveryoneofitsvisiblesurfacesismeanttoaidintheworkofheating.Thoughyouwillwanttochoosesomethingaestheticallypleasing,thethermalcharacteristicsandthicknessesofthosematerialswillaffecttheperformanceoftheheater.Thechoiceofveneermaterials,inaveryrealway,willdeterminehowwarmthemasonryheaterwillmakeyouandyourspaceatanygiventime.High-qualitymasonryheaterstodayconsistofmainlytwocomponents,the

innerlife(alsocalledthecore)andtheveneer.Theinnerlifeofthemasonryheater(seechapter8),whichincludesthefireboxandalltheflues,mustbeconstructedwithhigh-qualityheat-tolerantmasonrycalledrefractorybricks,plates,tiles,orconcrete.Thehighcombustiontemperaturesandthermalcycling—beingexposedtohighheatfollowedbylongperiodsofgradualcoolingfollowedbyintenseheatagain—necessitatealimitedrangeofhigh-qualitymaterials.Theexteriorveneer,however,isn’texposedtothesamepunishingenvironment.Theveneeriswherepleasingappearancemustbebalancedwellwithcost,reliablelongevityunderhotconditions,easeofmaintenance,and,asoutlinedhere,thermalperformance.Thefactorsthataffecthowwellaveneermaterialissuitedtothemasonry

heaterprojectarecalleditsthermalproperties.Thepropertiesofconcernarethematerial’sdensity,conductivity,specificheatcapacity,diffusivity,andemissivity.Thethicknessofthematerialisalsoofconcern.Seetheaccompanyingtable6.1forquickreferencetothevaryingcapacitiesofeachmaterialdiscussedbelow.

Density

Thoughsomewouldclaimthistobeadescriptivetermforayoungersibling,thedensityofatypeofbrickorstoneishowmuchitweighsperunitofvolume.Frequently,densityismeasuredinpoundspercubicfootorkilogramspercubicmeter.Youcangetanideaofdensitybylooselycrumplingasheetofnewspaper.Theballofpapermightbefairlylarge.Ifyoufurthercompressthepaperbetweenyourhands,youcanmakeitquitesmall.Itisstillthesamesheetofpaper;itstillweighsthesameamount.Thedensity,however,haschanged.Ithasbecomedenser—heavierperunitofvolume.Ifyoutrytocomparearocktoabrickofthesamesize,itmaynotbeobviouswhichoneisdenser.You’dhavetotakecarefulmeasurementsofboth.Ingeneral,adensermasonrymaterialcanholdmoreheatthanalessdensematerial.Sincestoringheatissomethingdesiredinmasonryheaters,densityisaplus.

Conductivity

Justassomematerialsaregoodatconductingelectricity,andsomepeoplearegoodatconductingorchestras,thermalconductivityisameasurementofamaterial’sabilitytoconduct,ortransmit,heat.ItisoftenmeasuredinBTUs(BritishThermalUnits)perfootperhourperdegreeFahrenheit(BTU/[fthr°F])orinwattspermeterperdegreeKelvin(W/[m°K]).Thehigherthisnumberis,thequickerthematerialtransmitsheat.Theideaofthemasonryheateristogettheheatofthefireintothelivingspaceoveracertainperiodoftime.Thosefamiliarwithacast-ironstoveknowthatheattransferthroughmetalisalmostinstantaneous.Indeed,metalconductsheataboutasfastasitconductselectricity.Thisfastconductivityisthereasonsomeonegetsburnedalmostimmediatelyupontouchingahotmetalstove.Allmasonrymaterials,ontheotherhand,aremanytimesslowerthanmetalattransferringheat,whichiswhyyoudon’tgetburnedbymasonrythatis200°F.

SpecificHeatCapacity

Thespecificheatcapacityistheamountofenergyrequiredtoraisethetemperatureofagivenamountofmaterialbyacertaintemperatureunit.This

necessarilymeansthatamaterialthatrequiresalotofenergytoincreaseitstemperatureby1°holdsitstemperaturewell.Thus,thespecificheatcapacityofamaterialistheamountofheatameasuredamountofmaterialcanholdwhenitstemperatureisincreasedincrementally.Inessence,thespecificheatistrulythemeasureofhowmuchheatasubstancecanhold.ThismeasurementisoftengiveninBTUsperpoundperdegreeFahrenheit(BTU/[lb°F])orinkilojoulesperkilogramperdegreeKelvin(kJ/[kg°K]).Since,unlikedensity,thisistheactualmeasureofheat-storagecapacityofa

material,itplaysaveryimportantroleintheabilityofamasonryheatertostoreheatforlongperiodsoftime.Combinethiswiththedensity(actually,multiplyitbythedensity),andyougetamaterial’sactualheatcapacity—howmuchheatitholdsperunitvolume,calledthevolumetricheatcapacity.

Diffusivity

Theverbdiffusemeans“tospread.”Aglobofpeanutbuttercouldbespreadwithaknifeoverbreadinacertainamountoftime.Inthermodynamics,diffusivityistherateofspeedatwhichheatspreadsthroughamaterial.Inatelevisioncommercialforpapertowels,atowelisplacedontopofapuddleofliquid.Rapidly,theliquidspreadsintothetowelinalldirections.Thisisrapiddiffusionofliquidintotheporesofthetowel.Youcanthinkofheatactingthesamewayinamasonrymaterial.Ifagivenmaterialhasahighrateofdiffusivity,theheattravelsquicklytoallitsregions,likewaterinapapertowel.Ifthematerialhasalowrateofdiffusivity,itislikewatchingthepapertowelcommercialplayedinslowmotion;theheatdiffusesslowly.Diffusivityismeasured,usually,inmeterssquaredpersecond(m2/s).This

rateisdeterminedbyusingthepreviouslymentionedthermalproperties;diffusivityisequaltotheconductivitydividedbythematerial’svolumetricheatcapacity.Thus,itisameasureoftheratiobetweenhowwelltheproducttransfersheatandhowwellitstoresheat.Masonrymaterials,withfewexceptions,aregoodheat-storagemediums.Thediffusivityvalueclarifiesfurtherhowquicklyagivenmaterialwillgetheatintoalivingspaceandhowevenlywarmthebodyoftheheaterwillbe.Thosematerialsthatconductheatmorequicklyhavehigherdiffusivityandmorerapidlylendheattothesurroundingareawhilestillstoringenoughforthedesignedheatingperiod.Diffusivityisanimportantmeasureinmaterialsformasonryheaters.Ideally,

amasonryheatersurfaceachieveshighenoughtemperaturesforqualityradiantheat,retainshighenoughtemperaturesforthedesignedperiodoftime,yetis

neverhotenoughtobeatouching/safetyhazard.Highdiffusivityamongmasonrymaterialsindicatesamorecompleteuseoftheheatgeneratedbyeachfire,assumingthematerialisofappropriatethickness.Materialswithlowerdiffusivitieswillstillbegoodatlong-termheatstorage,butlesseffectiveattheactualjobofheatingfromfiringtofiring,whencomparedwiththesameheater(ofthesametotalmass)builtwithmorediffusivematerials.

Emissivity

Mostpeoplebuildingorremodelinghaveheardoflow-ewindows.Theestandsforemissivity.Thesewindowsaredesignedtopreventheatfromradiatingoutofthehouseor,inthesummer,heatradiatingintothehome.Withmasonryheaters,thegoalistohaveexcellentradiantproperties,soamasonryheatershouldbebuiltusinghigh-emissivitymaterials.Fortunately,mostmasonrymaterialsarebothgoodabsorbersandemittersofheatenergy.Alas,therearestillmeasurabledifferencesbetweenmaterials.Emissivityisadimensionlesscoefficient.Itisactuallyacomparisonnumber

betweenthematerialinquestionandablackbody.Inscienceterminology,aperfectblackbodyisaperfectabsorberandemitterofradiantenergy.Suchaperfectbodyemitsallenergyavailabletobeemittedandabsorbsallradiantenergythatcontactsitssurface.Thisperfectblackbodyisgivenanemissivitycoefficientof1.Mostsolidbuildingmaterialsarerelativelygoodemitters.Masonrymaterials

asasetusuallyhaveemissivitycoefficientsrangingfromabout0.85to0.95.Thismeansthattheyhaveradiantproperties85to95percentasgoodasaperfectradiantemitter,theblackbody.Interestingly,castiron,typicallyusedformetalstoves,isarelativelypoorradiantmaterial,havinganemissivitycoefficientofabout0.24.Thereare,however,someimportantdifferencesamongmasonryoptions.

Thickness

Thethicknessofamaterialalsoplaysanimportantthermalroleinhowamasonryheaterworks.Asyoucanimagine,thethickeradensematerialis,thelongerittakestogetheatfromoneside(theinsideofthemasonryheater)totheother(theoutside),whereitradiatesintothelivingspace.Givenaspecificamountofheatproducedbyafire,awallthatis4inchesthickwillbemuchslowertogettheheattothelivingspacethanwillawallofthesamematerialbutonly2inchesthick.Athickermasonryheaterwall,then,ismoresuitablefor

heatstoragethanforheatdispersion.Awallthatisthinnerintroduceslessheatstorage,butgetsheatintothelivingspacequicker.Athickerwallofaparticularmaterial,givenconsistentapplicationofheatoverconsistentperiodsoftime,willprovideamoresteadysurfacetemperaturethanathinnerwallofthesamematerial.Simultaneously,thatmoreconstanttemperaturewillalwaysbelowerthanwouldbeexperiencedwithathinnerveneer.TABLE6.1.ThermalPropertiesofCommonMasonryHeaterMaterials

Asyoucansee,thevariousthermalqualitiesofthesedensemasonrymaterialshaveasynergisticeffectontheheater’sperformance.Ifaveneermaterialhasveryhighconductivity,butisnotgreatatstoringheat,thesurfacetemperatureswillbehigherbuttheheatwon’tlastverylong.Ifthematerialusedhaslowconductivityandisverythick,thesurfacetemperatureswillbemuchlowerandtheheatwillberetainedforaverylongtime.Ifthatsurfacetemperatureistoolow,thespaceisn’theatedaswellasitmighthavebeen.Everycombinationinbetweenispossible.Thequestionbecomes,therefore,“Overwhattimeperiodwilltheheaterbeexpectedtoheatandhowmuchheatisrequired(inthelivingspace)inthattimeperiod,beforethemasonryheaterisfiredagain?”Thisquestionisfurtheraddressedinchapter7.Allofthisiscomplicatedalsobytheamountoffuel(andthereforetotal

amountofheat)thatisexpectedtobeusedateveryfiring.Inagivenheaterdesign,afewcrumplednewspapersheetsburnedinthefireboxwillneverwarmallthemass.Attheotherextreme,ifinappropriatematerialswereusedforthedesign,anappropriateloadofcordwoodmayproducemoreheatthanthemasscanaccommodate,resultinginexcesslossesupthechimney.Agoodheaterdesignisgearedtothespacetobeheated;itproducestherightamountofheatwithaspecificamountoffuel,resultinginhighenoughsurfacetemperaturesto

heatthelivingspaceforthetimeperiodoverwhichitwasdesignedtoheat.Anyoneproposingtophysicallydesignandbuildamasonryheatershouldbefamiliarwiththesecomplexissuesandunderstandtheramificationsofthesedetailsbeforeproceedingwithaproject.Homeownerslookingtohaveaheaterbuiltdon’tnecessarilyneedtoknowallthesedetails.Theycan,however,usetheinformationinthischapterandthenexttoscreenwould-bebuildersandtounderstandthebasicsofwhycertainmaterialsandmethodsmayormaynotbethebestchoice.Table6.1,“ThermalPropertiesofCommonMasonryHeaterMaterials,”isaninvaluableaidtounderstandingthephysicalreasonsforchoosingamongthefollowingmaterials.

CommonBricksCommon,solidredbrickhasfrequentlybeenseenasafinishmaterialformasonryheaters.It’samaterialwellunderstoodandquicklyhandledbyexperiencedmasons.Asmasonrymaterialsgo,itisfairlyinexpensiveandreadilyobtainable,usuallyatanymasonrysupplyhouseinalmostanyareaofNorthAmerica.Askilledmasoncanofferspecialcoursingstyles,specialpatterns,andvariousarchesusingbricksofcommonsize,jumbosize,orevenRomanstyle.Sincebricksalsoareavailableinvaryingcolorranges,thelikelihoodisthatanyonewhogenerallylikesbrickcanchooseanappearanceandthemeusinglocallypurchasedcommonredbrick.Astable6.1shows,however,commonbrickratesthelowestofallcommonmasonrymaterialsinitsthermalproperties.Inaddition,commonbricksarequitethick.Atanominal4-inchthickness,theirperformanceasaveneermaterialonamasonryheaterispoorerthansomeothermaterialswhenitcomestoresponsiveness—theabilitytogetheatintotheroomquickly.

FIGURE6.30.Commonbrickisanoft-usedmaterialformasonryheaters.PhotocourtesyofEnvirotechMasonryHeaters.

Anotherconsiderationisthatbrick’srough,poroustexturemakescleaningalittlemorechallenging.Itcannotbesimplywipedwithaclothordustedwithafeatherduster—dirtreadily“sticks”totheporous,coarsesurface.

Stucco

Itisalittlemisleadingtoliststuccoasadifferentfinishbecausestuccorequiresasubstrateonwhichtobeapplied.Mostcommonly,stuccoisappliedoverbricks—preferablyfirebricks.Itcouldalsobeappliedoverconcreteblocks,thoughconcreteblocks,notbeingfired-claymaterials,arenot,intheleast,arefractory(heat-resistant)material.Stuccoaffordsavastnumberofsurface-finishoptions.Therearevarioustexturesandcolorsavailable.Somestuccoscanevenberepaintedwhenyourepaintaroomtochangeitscolors.Stuccocanbeswirled,brushed,andstippledinmyriadways.Ofcourse,itcanalsobeappliedverysmoothlyforaveryrefinedlookasinfigure6.33,orpossiblyasouthwesternlook.

FIGURE6.31.Thechimney(farright)ofthissandstoneheaterwasbuiltusinglong,thinRomanbrick.ProjectbyMarenCookeandKenMatesz;photobyMarenCooke.

Anotheradvantageofstuccoisthatyou’renotlimitedtousingbricksintheirthickestdimensionfortheunderlyingsubstrate.Infact,asuperiorheat-transferandheat-storagecombinationisobtainedbyusingfirebricks,laidasshiners,forthestuccosubstrate.(Shinersaresimplybrickslaidontheirnarrowedge,insteadofthetypicalbroadedge.)Thefirebrickwallhasadiffusivity15percentimprovedoverthered-brickconstructionaswellasgreatervolumetricheatcapacity.Althoughstuccoitselfhasfiguresroughlycomparabletoredbrick,itisnottheprimaryheat-storageandheat-transfermedium,soyoubenefitdirectlyfromafirebrickveneercoveredinstuccoversusthered-brickveneer.

RESPONSIVENESS

Responsivenessreferstohowreadilytheheatoutputofthemasonryheaterrespondstotheheatintroducedbyburningthefirewood.It’smuchlikethewayyoumightrefertoasportscarhavingresponsivesteering.Inacarwithgoodsteeringresponse,asmallmovementofthesteeringwheelimmediatelytranslatestoachangeinthedirectionofthecar.Aresponsiveheaterstartsradiatingheatrelativelyrapidlyafterafireandcanachievehigher

surfacetemperatures.Amasonryheaterthatisnotveryresponsivetakeslongertoget

warmer,andanincreaseinwoodusesometimesaffectsthedurationofheatstoragemorethanitinfluencessurfacetemperatureandimmediateheatoutput.Amasonryheaterwithtoomuchmassisconsideredsluggish.Asluggishheaterusuallyhaslowersurfacetemperaturesoverallbecausetheheatismovingsoslowlythattheexteriorcoolsalmostasfastasnewheatreachesit.Thoughallmasonryheatershavesomelevelofresponsiveness

andsomelevelofheatstorage,theidealmasonryheaterisveryresponsiveoverthetimeperiodinwhichitismeanttoheat;ithastherightamountofheatstoragetoassuretheheaterwillbeevenlywarmuntilthenextfiringcycle.Inwinter,onedaymaybecloseto32°F,andthenightmightdropto0°.Withasluggish(slow-response)heater,thereisnorealwaytoaccommodatesuchdrasticweatherchanges.Witharesponsiveheater,achangeintheamountoffuelusedresultsinmoreimmediateadjustmenttothechangingoutdoorclimate(andresultingdemandovertheshortterm)formoreheatoutput.Thickerveneerslikecommonbricksandmanynaturalstones

oftencombinelessimpressiveconductivityanddiffusivitywithexcessivemass.Thiscombinationcansometimesmakeaheaterthatisverysluggishindeed.Inhomesthatmayusemorethanonemasonryheater,onestrategyistouseamassive,sluggishheaterforprimarybulkheating,buthaveoneormoreheatersthataremoreresponsivetoadjustforrelativelyrapidchangesinheatingrequirements.Ifyou’regoingtobeusingonlyonemasonryheater,you’dbewisetokeepresponsivenessinmind.

Anotherplustostucco,forthosewhoparticularlywanttouseall-natural,mainlylocalmaterialsintheirproject,isthatnaturalclay-basedstuccosareavailable.Withthisidea,youcanliterallybuildahigh-outputmasonryheaterthatisalmost100percentclaywithnoPortland-basedmortars—thatis,claybricks,claymortars,andclaystucco!seechapter8formoreinformationaboutmaterialsusedinsidethemasonryheater.Stuccoshareswithbrickthecharacteristicofarelativelycoarsesurface,

especiallyifitisdeeplytextured.Ifthestuccoisappliedsmoothly,itisalittle

moreeasilycleanedthanabrickheater,sinceithasfewornomortarjointsthatcancollectdustanddirt.

NaturalStoneStoneremainsprobablythemostsought-aftersurfacematerialformasonryheaters.Onceuponatime,peoplegatheredaroundanoutdoorfirecontainedbyaringofstones.NorthAmericanpioneers,withoutaccesstomanufacturedbricksorothermasonryproducts,laiduptheiropenfireplaceswithriverrocksorstonesgatheredwhileclearinglandforfarming.Stone’slong-standinguseasafireplacematerialoverthecourseofhistoryhasalreadymadeitsmarkinthemasonryheaterworld.Fireandrocksaresuchbasicattractionsforhumansthatitisnowonderthatmorepeoplerequeststonefortheirmasonryheaterthanalltheothermaterialoptionscombined.Manypeopleevenhavedistantchildhoodmemoriesofawarmrockinthesunnexttoafavoriteswimmingorfishinghole.Itseemsquiteobviousthatwarmth,fire,stone,andpeoplearemeantforoneanother.

FIGURE6.32.Thisoneheaterdemonstratesseveralofthedifferentbrickcoursingandpatternoptionsthatarepossible.PhotocourtesyofMaineWoodHeatCompany.

Naturalstonecanbefoundinsuchavastarrayofstyles,colors,patterns,andtexturesthatvirtuallyanyaesthetictastecanbemetaswell.Randomstone,ashlarpattern,dry-stack,andlargeslabsallhavebeenandcanbeusedformasonryheaters.Granitehashuesrangingfrompureblack,throughvariousbluesandgreens,andontowhite.Marbleislikewiseavailableinmanyshades.There’sbluestone,limestone,sandstone,onyx,dolomite,slate,travertine,soapstone,andmore.Thereislittledoubtthatstoneoffersimmensedesignappeal.Somestoneveneerswillbesmooth,honed,orpolishedforeasycleaning,whileothershaveaveryroughtexturethatrequiresmoreefforttomaintain.Forallitsvariety,however,mostnaturalstonesposesomelimitationstothe

masonryheaterconcept.Usually,thoughnotalways,stoneisoneofthemostexpensivematerialstouseforconstruction,evenifyouhaveit“forfree”onyourproperty.Thecare,time,andphysicaleffortrequiredtoproduceexcellentstoneworkdemandsthatitcostmore,onbalance,thanotheroptions.Amasonlayingbrickscanworkalongatarapidpace,sinceeachpieceis

relativelyuniform,square,andstraight.Comparethiswith,say,arandom-patternstonefinish,inwhichamasonmayeitherspendconsiderabletimejustfindingastonethatfitsinagivenlocation,orspendsimilartimemakingthestonefitthatspace(orboth!).Eventhoughonesinglestonemaytakeupthesamespaceassixoreightbricks,theeightbrickscanbelaidinminuteswhilethesinglestonemaytakeanhourtofind,chisel,andfinallysetinplace.Ofcourse,thereare“stonemasons”whopridethemselvesmoreonspeedthanotherconsiderationsandcanlaystone,“swimming”inmortar,inveryshortorder,forlittleattemptismadetofitonestonetothenext.Thosewhoappreciatethisappearancemayfindamasonryheaterlaidinstonetobequiteeconomical.Anotherconsiderationwithnaturalstoneisitsthickness.Stoneis,bynature,

oftenveryirregularinsizeandthickness.Oftenappearancewilldemandthattheoverallwallthicknessoftheprojectwillbedeterminedbytheaveragethicknessofthethickestmaterialavailable.Forexample,ifthematerialathandis3to5inchesthick,andasignificantamountofitiscloseto5inchesthick,thentheprojectwillbelaidupasa5-inch-thickveneer.Likewise,stonesthataremuchthinnerthan3inchesaremoredifficulttolaystructurally.Therefore,itisverycommonforstoneveneersformasonryheaterstobeatleast3inchesthick—andmorelikely4to6intotalthickness.Asdescribedearlier,athickerveneerresultsingreaterheatstoragebut,

generally,lowersurfacetemperatures.Ifsurfacetemperaturesaretoolow,theheaterwillbeincapableofheatingthespaceforwhichitwasdesigned.Attheveryleast,ifthetemperaturesaretoolow,itcouldmeanthattheheatercouldhaveperformedbetterwithanothermaterial(orthesameone,butnotasthick).Ingeneral,moststoneveneersaretoothick,consideringthethermalpropertiesofthematerial,tomakeaveryresponsiveheater.Astable6.1shows,therearesomeimportantexceptionstothis.Thermalperformancevariesfromstonetypetostonetype.

FIGURE6.33.Ahighlyrefinedlookachievedwithstucco,aversatilematerial.It’susedinasimple,compactdesignwithclippedcornersandasmall“cupola”ontop.Notethesmallloadingdoorontheleftandtheabundantwoodstorage.PhotocourtesyofBiofire,Inc.

Thoughthereareconsiderablymorestonetypesthanarediscussedhere,thesearesomeofthestonesmostcommonlyavailableandusedformasonryheaters.You’llfindthatmanyoftheotherstonetypesarecloselyrelatedtogranite,limestone,orsandstonebycategory(igneous,sedimentary,ormetamorphic)andarethereforesimilarinperformance,ifnotincostandworkability.

Granite

Granitehasmadeahugecomebackrecentlyas,particularly,achoicematerialforcountertopapplications.Itsnearindestructibilityundernormalhouseholduseaswellasitscolorvarietymakeithighlydesirableforcounters.Inaddition,itcanbepolishedtoahighlusterthathighlightsitscrystallinestructureandcoloring,givingitatrulyexoticappeal.Graniteis,however,oneofthehardeststonesincommonuse.Itismuch

hardertoworkandshapethanthesofterstonesmentionedbelow.Thissimplymeansthatlaborcostsforinstallingitwillbeamongthehighestwithinacategorythatisalreadyofahighercost.Inaddition,graniteitselfisanexpensivestone.Ifit’snotalreadyavailableonsite,itwillbeexpensivetopurchaseandshiptothesite.Figure6.34isagoodexampleofagranitemasonryheater.

FIGURE6.34.Hereisawonderfulexampleofafinelycraftedstonemasonryheater.Thedarkgraniteheatedbenchesandheatercapcontrastwiththelighterstoneusedonthemainbodyoftheheater.PhotocourtesyofMaineWoodHeatCompany.

Limestone

Anotherverycommonstone,limestone,likegranite,hasbeenusedinconstructionforthousandsofyearsandisstillacommonfeatureinmasonryworkofmanykinds.Limestone,owingtoitsnamesake,lime—whichreadilytakesonthetintofoxidizedmineralsthatmayhaveaccumulatedinit—canrangeincolorasfullyasgranite.Therearewhite,gray,black,orange,andredstonesinthisfamily.Travertineiscloselyrelatedtolimestonebecauseofitscarbonateingredients.Ingeneral,limestoneiseasiertowork,becauseofitssoftness,thangraniteandcanevenbe“polished”withgoodsandpaper.Simple

steelchiselsthatwouldbeineffectiveongranitewillsplitlimestoneeasily.Limestonealsoiseasiertoquarryandcutthangraniteormarbleandsotendstobealesscostlystone.Somelimestonevarietiesareeventoosoftforcommonstructuraluse.Well-knownlimestoneproductslikeIndianalimestone,ontheotherhand,areexcellentstructuralstonesthathavebeenusedextensivelyforbuildingforcenturies.

FIGURE6.35.Anowner-veneeredlimestonemasonryheater.Thesandstoneslabsusedovertheheatedbenchesandasthecappingstonesatthetopoftheheaterarefromanoldsidewalk.

Sandstone

Asitsnameimplies,sandstoneisasedimentaryrockcomposedlargelyofsandparticlesfromvarioustypesofrocksandminerals.Likemanystones,itisavailableinmanycolorsrangingfromsimplewhitesandtanstodeeplystriatedorcoloredstonesofred,brown,andyellow.Also,likemoststructuralstonetypes,sandstonehasbeenusedforcenturiesthroughouttheworldforconstructionprojectsofeverykind.Sandstoneisoftenthematerialyouseeinpatiofloorsfeaturinglargeflatstones,calledflagstones.ItisveryplentifulandfoundingreatquantitiesintheUnitedStatesandabroad,makingitalower-coststonetobuyanduseforvariousprojects.Sandstoneisalsorelativelyeasytoworkandshape.Likelimestone,commonsteelchiselsandotherstoneworking

toolsareeffectiveforshapingsandstone.Figure6.36showsaheaterbuiltwith5-to6-inch-thickslabsofsandstone.FIGURE6.36.Amassiveheaterincorporatingthickfree-formslabsofsandstone.Themainfrontbenchslabaloneweighsnearly1,200pounds.Thissameheater,viewedfromtheoppositeside,isshowninfigure3.1.ProjectbyMarenCookeandKenMatesz;photobyMarenCooke.

FIGURE6.37.Thisisamassivesplit-soapstone-facedmasonryheatermadewithstonefromFinland.Noticethecarvedsceneinthestoneabovethefirebox,asmallwarmingcompartmentwithawoodendoor,andalargewood-storageniche.PhotocourtesyofTulikiviCorporation.

Soapstone

Therearegoodmaterialsformasonryheaters,andthereissoapstone.Thedifferencesinthermalperformanceamongthevariousmaterialscanseemimportant,untilallofthemarecomparedwithsoapstone.Addtothisfacttheinformationthatsoapstoneisveryeasytocutandotherwisemodify,polish,andcarveandIbelievethatsoapstoneis,byfar,asclosetobeingtheperfectmaterialformasonryheatersashumankindwilleverfind.Soapstoneisacompletelynaturalstonethatisfoundallovertheworld.Some

depositsareverysoft.Theseareconsideredthecarvinggradesandareusedforallmannerofartwork.Otherdepositsaremuchharderandyieldsoapstonethatisappropriateforarchitecturaluseincludingconstructionofwalls,floortiles,andmasonryheaters.SomeofthehardersoapstonecomesfromFinlandandisusedforheatersliketheoneshowninfigure6.37.

Soapstone,alsocalledsteatite,isametamorphicrockformedunderheatandpressurefromolivineandothermineralcomponents.Oneofitsprincipalmineralcomponentsistalc,whichisfamiliarastalcumpowder.Itisthetalccontent,makingupmorethanone-thirdofsoapstone,thatgivesthestonea“soapy”feel.Thetalccontentalsoisresponsibleformakingsoapstoneeasytotoolandcut.Soapstone’shardnessandstrengthcomeprimarilyfromitsmagnesitecontent,alsomorethanone-thirdofitscomposition.Soapstone,likegranite,hasreceivedmoreattentioninrecentyearsasa

kitchencountertopmaterial.Longbeforethat,however,itwasusedascountertopmaterialinchemistrylabsallovertheworld.Thereasonforthisisthatsoapstoneisnotdamagedbymostextremechemicals.Forexample,strongacidswillnotdamagesoapstone,andonlyverypowerfulalkaliswillcorrodeit.Inotherwords,soapstoneisnotsubjecttostaininganddamagefromcommonhouseholdfoodsandchemicals.Unlikegranite,soapstonecanbeeasilydamagedbysharp,hardobjects;atthesametime,scratchesinsoapstonecanbeeasilyrepaired,whichisnottruewithgranite.Distinctfrommostothernaturalstones,thestructuralvarietiesofsoapstone

arenotaseasilyfoundinabroadspectrumofcolors.Thoughredsandothercolorsexist,moststructuralgradesofsoapstonehaveagrayishhue,thoughtheirunderlyingcolorscanrangefromgreentodarkblue.Allofthese,ifhonedbymachine,leavealightgrayappearance.Althoughthiscolorisneutralandcomplementsmanyothercommonbuildingmaterials,includingmostwoodsandmostotherstonetypes,thereareindividualswhosimplyarenotdrawntothisgrayappearance.Othersfinditssofthuesandmarble-likeveiningtobeincrediblybeautiful.Whatevertheaestheticpreference,soapstoneis,likegranite,amoreexpensive

stone.ThestructuralsoapstoneneededformasonryheatersisnotreadilyavailableinalllocationsofNorthAmerica.SomeofitisimportedfromCanada,Finland,Brazil,India,andevenAfrica.Becauseitisnotlikelytobefoundjustlyingabouttheproperty,itwillhaveahighercostthanthemanymorecommonstoneslikesandstone,limestone,andevengranite.Theeasewithwhichitcanbeworked,however,candecreasethelaborcostassociatedwithusingitinamasonryheaterproject.Becauseofthisanditsthermalperformance,soapstonedeservestheattentionofanyoneconsideringamasonryheater.

FIGURE6.38.Soapstonealmostalwayshasagrayappearanceonmasonryheaters,butitoftenhasmarble-likegrainingthatgivesitgreatcharacterandenduringbeauty.Thewingbenchesherearenotheated.Noticecylindricalstonesencasingthechimney.Thiswouldbedifficulttodowithmostotherstones.TulikivistovebyMasonryHeaterStore.

Astable6.1illustrates,soapstoneeasilyqualifiesasthepremiermaterialforheat-storagefireplaces.Inmostcases,asoapstoneheaterisn’tfourtosixtimesmoreexpensivethanbrickorotherstonemasonryheaters,thoughitsthermalperformancecharacteristicscanbeatleastfourtimesmoresuperior;itdeservescarefulconsiderationasaveneermaterial.

FIGURE6.39.Lotsofsoapstonetranslatesintolotsofheatstorage.Thisheaterisalsoseenfromanotherangleinfigure4.16.PhotocourtesyofNewEnglandHearthandSoapstone.

Tile

InGermany,Austria,Hungary,andotherEuropeancountries,thetilestove,orkachelofen,hasbeenubiquitousforcenturies.Ofcourse,akachelofen,asmentionedbefore,isamasonryheater.Figure6.40showsaclassictilemasonryheaterfromtheoldcountry.IntheUnitedStates,whenthewordtileisused,italwaysconjurespicturesoftheceramictilesusedonbathroomorkitchenfloors,counters,orwalls.ThisistheNorthAmericanexposure,usually,totile.Itisnosurprisethatwhentileismentionedasamasonryheatersurfaceoption,peopleenvisiongoingtotheflooringoutlettopickouttherightmaterialforthejob.Therealityisthat,althoughfloortilescanbeconsideredforuseonmasonryheaters,realmasonryheatertilesarejustlikethoseusedonEuropeanheaters.

Kacheln(tiles)dosharewiththeirfloorandcounterrelativesabasicallyimperviousglazedsurface.Tilemasonryheatersareamongtheeasiesttokeepcleanandlookingnewbecausetheycannotbestainedordiscoloredandhavesuchasmoothsurface.Likeanytile,kachelnareavailableinawholerainbowofcolorsfromearthytonestopastelstobright,almostfluorescent,shades.Thenearlyunlimitedcolorrange,goodthermalperformance,andappropriatethicknessofmasonryheatertiles,aswellasthefactthattheycanbehandmadeinvirtuallyanyshapeandsize,makesthetiledmasonryheateroneofthemostpromisingandversatileoptions.

FIGURE6.40.Thisisafineexampleofamasonryheaterwithanexteriormadeentirelyoftiles.PhotocourtesyofNewEnglandHearthandSoapstone.

FIGURE6.41.ThebacksofheaterkachelnrevealtherumpfthatmakesthesetilesdifferentfromtheflooringandwalltilesmostAmericansknow.ProjectbyNewEnglandHearthandSoapstone;photobyKenMatesz.

Amasonryheatertiledifferssignificantlyfromacommonfloororwalltileinthatitisamuchmorethree-dimensionalandstructuralcomponent.Whileflattilesneedtobeadheredtoaflatsubstrate(usuallybrickifusedinamasonryheaterapplication),aregularkachel(stovetile)isdesignedtobetheactualstructureofthemasonryheaterexterior.Inappearance,suchatile,onthefinished,glazedexterior,mayindeedlook

likesomecommontiles.Ontheback,however,ithasanappendagecalledarumpf.Theback(seefigure6.41)lookslikeatilethathashadabowlordeepdishattachedtoit.(Suchatile,thougharound2inchesthick,isprincipallyhollowonthebackside.)Therumpfisnecessarytoconnectneighboringtilestogether,whichisdonewithwireclampsmadeofsteel.Kachelnarenotsimplygluedtoasubstratethewayfloortilesare;rathertheyaresetinclaymortarandmechanicallyfastenedtooneanother.Flattilescementedtoasubstratemayormaynot,inthelongrun,survivetheexpandingandcontractingofthemasonryheater.Seefigure6.42foranexampleofamoderntileheater;anotherrecenttileheatercanbeseeninfigure2.1.

FIGURE6.42.Arealkachelofen;it’samasonryheaterbuiltwithstructuraltiles.PhotocourtesyofBiofire,Inc.

PressedEarthorAdobe

Thoseinterestedinlow-embodiedenergy,localmaterials,andsustainableconstructionmethodswillbeparticularlyinterestedincombiningamasonryheater’sbenefitswithavailable,on-sitematerialslikeclayandearth.Buildingwithearthisasoldasconstructionitself,andbuildingswithearthenwallscanbefoundallovertheworld.Perhapsoneofthemostcommonlyknownearth-constructionmaterialsistheadobebrick.Adobeislittlemorethanclay,sand,andwatercombined,setinbrickforms,andallowedtodryinthesun.Similarly,pressed-earthblocksareoftenapredominantlyclaysoil,sand,alittlecement,andsomewatercompactedmechanicallyintoadensebrick.Allsuchbricksmayhavesomeplantfibersaddedasreinforcementinamannersimilartoaddingsteelorfiberstoconcreteforaddedstrength.Inessence,adobeandotherearth-basedconstructionmethodsaretheprecursorsofmodernbrickconstruction.Bricks,afterall,areprimarilyclayalso.Amajordifferenceisthatcommonbricksorfirebricksarealsofiredatveryhightemperatures,whileadobeor

pressed-earthblocksgenerallyarenotsubjectedtomorethannaturalsunlight.Theoreticallyspeaking,youcouldconstructamasonryheaterentirelyfrom

handmadebricksofthisnature.Evenfirebrick,theusualchoicefortheinnerlifeofthemasonryheater,isafired-claybrick.Theideaofusingentirelylocal,on-siteearthandsimplehumanenergytomakebricksandbuildamasonryheatercouldexcitemanyavidenvironmentallymindedbuilderswithenoughtimetodevotetotheproject.However,itisvitaltounderstandthatthereare,indeed,reasonswhymodern

refractoryfirebricksandcommonbricksarethenorm,andpressed-earthandadobebricksarenot.Atleastoneofthosereasonsisthatfirebricksarespecificallyandcarefullydesignedtowithstandtheabusesofdailyhotfireswithoutdeteriorationformany,manyyears.Thesamecannotbesaidforhand-pressedorsun-driedearthbricks,whichwilldeterioraterelativelyrapidlyunderthevariousforcesatworkinmasonryheaters.Thereismechanicalabuse(fromfirewoodloading),thermalshock(periodsofsignificantcoolingfollowedbyrapidheating),andtheabrasionanddeterioratingeffectsoftheexhaustsofwoodfires.Whileit’sgrandtohavevisionsofminimumenvironmentalimpactbyusinginexpensive,self-madebricksandmortar,youneedtoconsidertheimmensetimelossofbuildingthiswayonlytohavetorebuildthestructureinthenot-so-distantfuture.Itisthereforemorereasonabletoconsiderusinghandmadebricksonlyforthe

exteriorveneer.Evenhere,though,youmustbeawarethatadobebricksarelikelytohaveevenlowerthermalperformancecharacteristicsthancommonbricks,whicharealreadylowonthescale.Thefactthatmanypressedorhand-formedbrickscontainplantfibersandsuchmeansthattheyhavelowerconductivity,lowermass,andcorrespondinglylowheat-storagecapacity,diffusivity,andsoforth.Althoughlittleactualdataexistsforadobebricks’thermalperformance,theircloserelationshiptostandardbricksmeanstheyarenotgoingtoperformanybetterthanthemanufacturedvariety,andlikelysomewhatworse.

WhatAretheOptions?

Masonryheatersarethemostversatilewood-burningdevicesintheworld.Becausetheydonotdependonachimneyfromthetopofafirebox,the

arrangementofthedesignelementsislimitedonlybyimagination.Fireboxes,heat-storagemass,andchimneyscanbeseparateelementsofvirtuallyanyshape.Additionalfeaturessuchassittingareas,warmingnooks,andwood-storagenichescanbeaddedtothedesign.Inadditiontothisamazingflexibility,masonryheaterscanbeveneeredwithanymasonrymaterialimaginable,fromcommonbrickstohandmadetilestonaturalstone,eachwithuniquethermalproperties.Nowthattheseuniqueelementshavebeendiscussed,it’stimetoexplorehowtoknowwhatsizemasonryheaterisneededinagivenlivingspace.

DESIGNINGFUNCTIONALARTWORK

Foraslongaswe’vecontemplatedbuildingahouse,we’veknownthatwewantedamasonryheater.Theyareclean,efficient,beautiful,andtheyutilizemoderncarbonratherthanthefossilcarbonusedtoheatmosthomes,akeydifferenceforglobalclimatechange.Asitturnsout,wedidn’tbuildanewhouse;we’vespentthelastsixyears(andcounting)expandingandrenovatingahousedatingfrom1950.ThoughIgrewupinthewoods,andvaluebeingclosetonature,wechoseto

liveinthecitywheremyspouse,Neil,cancommutebybicycle(he’sanatmosphericchemistonthefacultyofCarnegieMellonUniversity).Butwearelivingmoreorlessinthewoods,aswe’reontheedgeofa600-acreurbanforest.Ispendmostofmytimeworkingonthehouseandonvariousgardensinourlittlepermacultureoasis,aswellassometeaching,consulting,andvolunteeringonissuesofurbansustainability:airquality,landuse,andlocalandurbanagriculture.Wehavetwodaughters(whousuallybikeorwalkuptothelocalpublicschool),whohaveenjoyedbeingnestledintothewoodsasweare—andseeing(andsometimeshelping)thehousecometogether.Asanartist,itwasajoytodesignandbuildtheheaterandsurrounding

structuralmemberstogetherwithacoupleofexpertsintheirrespectivefields.Onthestructuraldesign,wecollaboratedwithanarchitectbutalsohaddefiniteideasofourown.Thearchitectdeterminedtheengineeringrequirements,butwefeltfreetoalterthematerials,layout,andotheraspectsofthebuildinginacontinuousconversationwithhim.Themainroom(showninfigure6.31)woundupbeingremarkably

reminiscentofthehousemyparentsbuiltfromscratchinthewoodsoftheHudsonValley,withtree-pillarssupportingradiatingoakbeamsandagreatmanywindowsconnectinguswiththeoutdoors.Ratherthanaheaterand

supportpillarsofbrickasfirstenvisionedbythearchitect,wehavebranchingtreesrisingoutofastonehearth,andabrickchimneybesidethestoneheater.(Oneofthebeamsheldupbythetreeswaslongerandwiderthanstructurallynecessary,soIsettocarving;nowwehaveoakleaves,acorns,Celticbraiding,andadragonoverlookingthelivingroom.)WewereabletosalvageenoughRomanbrickfromtheoldexteriorwallofthehouseandanonfunctionalchimneytobuildthenewchimney.Thechimneybeingrectangular,itseemednaturaltouseamediumlikebrick,butforthehexagonalheaterIfeltthatmoreorganicformsandnaturalmaterialswereinorder(andwewouldbeunabletomatchtheexteriorofthehouse,asRomanbrickisnolongergenerallyavailable).Thesandstonewechosecamefromonly50and100milesaway.Ahugeslab

ofMarylandRedsandstonewascutintosectionsforthefree-formhearth,partlytomakethesectionssupportingtheroofstructureseparatetoallowforexpansionandcontraction.Thelargestsectionisabroad,raised,heatedhearth.Thisparticularchunkofstoneweighedcloseto1,200pounds,sowesetitintoplaceusingablockandtacklesuspendedfromthestoutoakbeamsabove.Thenaturalweatherededgeofthesandstoneslabgoesallaroundtheoutsideofthewraparoundhearth.Sincetheoriginalslabwaslargerthanthefootprintofthehearth,however,Ken[Matesz]andIwereabletocuttheremainingmaterialsothatthefirst31.2feetoffacingabovethebenchesallcamefromthesameslab—somepiecesaslargeas2by3feet,othersintheformofstripsthatweplacededge-onbeneaththemantels.Abovethatlevel,thestoneismostlyglacialtillfromjustnorthofPittsburgh.Thestoneveneeronourheaterrangesfrom4to6inchesthick.Kenbuiltthe

coreandhelpedmedothestoneworkuptothemantels.Ifinishedthestoneworkastimepermittedandincorporatedergonomicallyshaped“backstones”wherethechimneymeetsthehearth.Fortheratherheftycapstone,wehadfriendsoverforastone-raisingparty.

FIGURE6.43.MarenCookerelaxesontheheatedbenchofherartisticcreation.ProjectbyMarenCookeandKenMatesz;photobyMarenCooke.

Adecisionmadeduringthecoreconstructionphasekeptusfromburningtheheaterforseveralyears.Tryingtogetthemostenergypossibleoutofthewoodweburn,wehadKeninstallahot-waterjacket,astainless-steelpipepassingthroughthestonefacingandthefirebrickcorewall,whereithugsonesideofthefireboxbeforeloopingbackout.Ifthehousehadbeendesignedaroundthemasonryheater,wewouldhavemadethehousemorecompact;thehot-watertankwouldbeonthesecondfloor,andnaturalconvectionwouldcirculatethewater.Wehavenosecondfloor,though,andourhouseholdplumbingfeedsfromtheareabelowtheheater.Inaddition,thenecessarypumps,valves,andheatexchangersarefairlycomplicatedandexpensive,especiallyincombinationwithareasofradiantfloorinthebasementandfuturesolarthermalpanelsontheroof.Thewaterjacketremainedunconnectedandwecouldnotfiretheheaterwithoutriskingdamagetothepipe(sincetherewasnothingcirculatingtokeepitcool).Intheinterim,wewentwithouthotwaterforalmostfourmonthsonewinterwhileItriedtoeco-optimizethereplacementforadeadwaterheater.Recentlyafriendwhoisanexpertonsteelhelpedusdeviseaworkaroundby

circulatingairthroughthepipeinsteadofwater.Now,insteadofamulti-thousand-dollarsysteminthebasement,wehaveaforty-dollarventilationfanandsomecopperfittings.AndIhavebegunthinkingaboutareallyniftyheateddryingrack...Becausethestoneworkdriedunderaroofforyearsandtheconcretehadso

longtocure,weacceleratedtheinitialbreak-inprocesssomewhat,burningtwosmallfiresadayforaweek(firstjustkindling,workinguptofullloads).Severaldayswentbybeforetheexteriorstartedgettingwarm.Kenhadforewarnedusthatwewouldgetlittleheatfromtheinitialsmall“break-in”fires.Ittakessometimeforheatfromalittlefirewoodtoinitiallywarmthatmuchmass.Thelargerfireswarmeditnicely.Thefirebox,afterwebeganusingfullloads,wassoonscouredcleanbytheheat.Thesecondarycombustionchambertooklongertoself-cleanandliveduptoitsnameblackovenforawhile.Itwasslowtoheatup,withthemassivestonesurroundingit,butdidanicejobearlyonroastingsomepumpkinsforpie—andhasbakedsomefineloavesofbread!Nowwecanbreakbread(aswellassharelovelyfires)withfamilyandfriends,withoutfeelingguiltyaboutwood-burningemissions—anotableconcernforanair-qualityactivistandanatmosphericscientistinaregionwithseriouspollutionissues.

byMarenLeylaCooke,Pittsburgh,Pennsylvania

FIGURE7.1.Thisisaverystraightforward,elegant,andwell-placedbrickmasonryheater.Noticetheinsetherringbonebrickpatternabovethemantel.Theheaterwasbuiltallthewaytotheceiling,givingtheimpressionofthehugemasscontinuingon,thoughtheworkingsofthisheaterendabout1footbelowtheceiling.PhotocourtesyofEnvirotechMasonryHeaters.

CHAPTERSEVEN

HeatingRequirementsoftheHouse

Wouldanyonebakecookieswithoutknowinghowmuchflourtouse?Doesatravelersetoffonatripwithoutknowingadestination?Shouldyoubuyahouseifyoudon’tknowtheprice?Youcouldansweryestoanyofthesequestions;yetmostofuswouldratherhaveaplanofaction.It’ssensibletoknowtherecipebeforestartingtocook.Itcertainlyiswisertoknowwhereyou’reheadedbeforesettingoff.It’sreasonabletocheckpricesbeforecommittingtoasale.Itislikewiseagoodideatoknowhowmuchheatisrequiredforaspacebeforehavingamasonryheaterinstalled.Inmostnewhomeconstruction,aheating,ventilating,andair-conditioning

(HVAC)specialistexaminestheplansforthehouseanddoesacarefulanalysistodeterminewhatsizefurnaceand/orairconditionerisneededforthespace.All2,000-square-foothomesarenotcreatedequally.Differentroofpitches,differentframingsizesorspacing,differentkindsandnumbersofwindowsanddoors,anddifferentkindsandamountsofinsulationallinfluencehowmuchheatisrequiredforaparticularlivingspace.Evenasingle200-square-footroominonehousewillnotrequirethesameheatingasthesameroominanother.Onemighthavewoodfloors,theothercarpet.Onemighthavefivewindows,theothertwo.Youmustlookatallthepertinentfactorstodecidewhatkindofheaterisneededforeachlivingspace.Theothersideofthiscoinisthatallmasonryheatersarenotcreatedequally,

either.Aschapter6described,differentconfigurationsandmaterialswillperformdifferently.Evenasingledesignbuiltwithdifferingmaterialswillperformdifferently.OnerelativelysimpledesignisbasedonatraditionalFinnishcontraflowheater.(Youcanreadmoreaboutthisinchapter8.)Thereareseveralcorekitmanufacturersofheatersofthisgeneraldesign.Thoughoneofthesekitsmaybeassembledthesamewaywiththesametypeofrefractorymaterials,theexteriorsmaybefacedverydifferentlybydifferentmasons,withdifferentbricks,stones,mortar,andotheroptions.Alloftheseseeminglyinsignificantdifferencescanmakeaheaterthatfunctionsinsignificantlydifferentways.Cookie-cutterheatersdon’tnecessarilygivecookie-cutterresults.

Inaddition,eachhomeownerhasindividualpreferencesandgoalstobeachievedwithamasonryheater.Youmaybelookingforwardtobeingentirelyenergy-independent.Notonlythat,butyoumaywanttoenjoyafirethreetimesperday.Anotherindividualmaybelookingtosimplyheattheprimarylivingspacethroughmostoftheheatingseason,butmaybeunconcernediftheheaterwillnotheatthewholespaceonthecoldestdaysoftheyear.Thispersonmaywanttoknowthatthiscanbeachievedbyheatingtheapplianceonlyonceperday.Yetanotherpersonmaybelookingatthemasonryheaterasbeingonlyabackupsourceofheatinemergencysituationsandmayhavelessconcernabouthowoftentheheaterneedstobefired,solongasitwillbeadependablesourceofemergencyheating.Eachhomeownerneedstobeshownawaytoachievehisorherheatinggoals.Thischaptertakesasitsstartingplacethisbasicquestion:“Overwhattime

periodwilltheheaterbeexpectedtoheatandhowmuchheatisrequired(inthelivingspace)inthattimeperiod,beforethemasonryheaterisfiredagain?”Thisquestionmustbeadequatelyansweredwithintheframeworkofwhateverotherphysical,budgetary,andaestheticdemandsyouoryoursiteconditionsmayplaceontheproject.Thereisnoone-size-fits-allanswertoeverysimilarproject.Somethingassimpleasachimneythatis10feettallercancompletelychangetheoutcome.

FIGURE7.2.Theheaterpicturedhereisthesametypetheauthorsometimestakestohomeshows.

It’samedium-sizedsoapstoneheaterwithabakeovenoption.PhotocourtesyofTulikiviCorporation.

Thoughthistypeofspecificityissoundadvice,itdoesnotmeanthatmasonryheaterdesignissorigidthatoneheaterdesigncanonlyworkinoneparticularhouse.Infact,thoughtheprecedingstatementsstemfromdesigningaheatertofitaparticularlivingspace,itisalsoperfectlypossibletodothingsanotherway:Youcan,instead,startwithaheaterdesignandbuildahomeorlivingspacearoundit.Agivenheater,facedwithspecificmaterials,willimpartspecificamountsofheatoveraspecificperiodoftime.Knowingthis,aprimarylivingspace,or,indeed,awholehouse,canbedesignedsuchthatitiscertainthattheproposedheaterwillfulfillalltheneedsofheatingthatspace.Similarly,ifyouhavemoreflexibledesiresastohowmuchspacemustbeheatedwithamasonryheater,youmaybeabletouseoneofmanydifferentdesignstoachievetheseends,thoughit’sstillworthwhiletounderstandtheramificationsofthechoiceofadefiniteheatingdevice.Masonryheatershavebuilt-inversatility,butsomeofthatcomeswithaprice.

TheVersatilityofMassItiscommonforpeopleseeingmasonryheatersforthefirsttimetothinkofthemasovergrownwood-burningstoves.I’veownedaportable,lightweightmasonryheatertotaketohomeandgardenshowsforyears.Invariably,someonerecognizesitassomekindofheatingstovethatisatleastdoublethesizeofmanytypicalmetalwood-burningstoves.Theycommenttotheircompanions,“Youhavetohaveareallybighouseforastovelikethat!”Theirassumption,basedonthepropensityofmetalstovestooverheatbecausetheirheatisunfetteredbyanysubstantialmass,isthatallwood-burningappliancesarelikewiseuncontrolledheatproducers.Inreality,theactualmasonryheaterofwhichtheyareseeingareplicaisdesignedforliterallyjustthemainlivingareaofacommonhome—perhaps1,000squarefeetofspacewith8-foot-highceilings.What’smoresignificantisthatamasonryheaterofthissizecouldbeputinto

asmallerspace,likeasinglefamilyroomofjust400or500squarefeet,andstillbeusedeffectivelyandwithoutoverheatingthespace.Thereasonforthisisthatit’sthewarmmassthatheatsthelivingspace,notthefireitself.Theamountoffirewoodused,orhowoftenafireisburned,determineshowwarmthemassgets.Theheaterthatcouldheat1,000squarefeet,usingaloadoffirewoodonce

perday,mayverywellheatthesmallerspaceusingafirewoodloadeverythirty-sixhoursoreveneverytwodays.Quitesimply,morefirewoodwarmsthemassmoresignificantly(makesitwarmer)sothatitcanthenheatalargerspace.Lessfirewoodchargesthemasswithlessheat,whichthenprovidesmilderheattothearea.Thisflexibilitydoesnotcomewithoutacost,however.Thereareatleasttwo

hiddencoststotheplanofusinganoversizedmasonryheater.First,installingaheaterthatislargerthannecessaryforagivenspacewillusuallycostmoremoneythanamoreappropriatelysizedmasonryheater.Thisiseasilyforeseenandunderstood.Thereisalsoariskofgreaterinefficiencyinactualeverydayuse.Theinefficiencymaynotbequitesoobvious—atleastnotatfirst.Sincesuchaheaterwillprovidethegentleradiantheatyoudesireforaspace,itmayseemjustfine.Therearetelltalesignsofinefficiency,however.Amasonryheaterismeanttobeaclean-burning,efficientwayofusing

firewood.Theprincipalmeansofachievingefficiencyandcleanlinessistoburndryfirewoodatveryhightemperatures.Theabove-mentionedheater,designedfor1,000squarefeetoflivingspace,hasafireboxandmasscreatedtoabsorbtheheatfromenoughfirewoodtowarmthatmasssufficientlytowarma1,000-square-footarea.Ifsaidheaterisgoingtobeusedtoheatonlyhalfthatspace,itwillneedmuchlesswood.Theresultofburningsignificantlylesswoodthanthatforwhichitwasdesignedisthatachievingthehightemperaturesforclean,efficientcombustionissimplynotpossibleinthatfirebox.Asmallerpercentageoftheavailablefuelisthereforeactuallyconsumed,andmoreofitescapesoutthechimney.Morethanlikelyyou’llnoticethatthefireboxalwayshasacoatingofblacksoot.Sootwilllikewisecondenseondoorglassand,verylikely,creosotedepositswilloccurthroughoutthefluesandinthechimney.Suchascenariointroducesgreatermaintenanceissuescombinedwithgreaterenvironmentalissuesbecausetheoversizedmasonryheaterisnotoperatingwithinanoptimumrangethatpromotesclean,efficientcombustion.Theversatilityofahigh-massheat-storagedevicelikethisis,then,agood

thingtoapoint.Itiswisetohaveaheaterwithsomeexcesscapacitysothatduringlongspellsofunusuallycoldweather,theheatercanmeetthechallenge.Likewise,itisgoodtoknowthatwhentheweatherturnsmilder,youcanfireitlessfrequentlyorwithlesswoodandstillexperienceitssubtle,radiantheat.Aswithanyengineereddevice,therearelimitswithinwhichyoushouldstrivetoremain.Thegoalshouldbetomeetmaximumheatdemand,accommodateminimumdemand,andallthewhileassurecleanandefficientcombustion.This

goalismetbyproperlysizingeitherthelivingspacetotheproposedheaterorbydesigningorspecifyingaparticularheaterfortheexistingspacerequirements.

HeatingRequirementsThefirststepindesigningamasonryheateristoknowhowmuchheatisrequiredforthegivenspaceoveraparticulartimeperiod.Intermsofahomeinacoldclimate,theheatingrequirementsofthatspaceareequaltotheamountofheatthatthebuildinglosesoveraperiodoftimeataspecifictargetindoortemperature.Thisheatingrequirementcalculationisoftenreferredtoastheheat-losscalculation.Obviously,ifastructureneverlostanyheatthatwasproducedorcollectedwithinitsconfines,itwouldforeverstayatornearthetemperaturesproducedbythatheat.Practicallyspeaking,zeroheatlossisimpossible.Everybuildingmaterial,

includinginsulation,hassomecombinationofporosity,conductivity,andadegreeofleak-proneness.Inaddition,thickinsulationrequiresthickwallsthathavetypicallyhighlaborandmaterialcosts.Windowanddooropeningsarepronetotinyleaks,whileglassitselfisapoorinsulator.Andofcourse,peoplegoinandoutofhouses,exposingtheindoorstothecoldoutdoors.Thus,therearetwoprimarywaysinwhichheatislostfromabuilding.Eitheritislostbecauseheatconductsthroughmaterialstotheoutside,oritislostbecauseofsomekindofleak,oftencalledinfiltration.Therereallyisnowaytocompletelypreventheatlossfromadwellingfromtimetotime.Thiscontinuouswinterheatlossisthewholereasonforheating.

WHATAREBTUSANDKILOWATTS?

BTUstandsfor“BritishThermalUnit,”whichissimplytheamountofenergyrequiredtoraisethetemperatureof1poundofwaterby1°F.(Thisdefinitionassumesliquidwaterandstandardatmosphericpressure.)Whenspeakingaboutmasonryheaters,BTUsareusedtorefertothepowerproducedbytheheater.Powerisenergy(orwork)deliveredoveraperiodoftime.Youmightsay,forexample,thataparticularmasonryheateroutputs10,000BTUsperhour.Inthiscontext,you’lloftensimplyseethemeasurein“BTUs”;thehourunitsarepresumed.

Akilowatt(kW)is1,000watts.Again,awattisaunitofpower.Mostpeopleknowthata100-wattlightbulbgivesoffmorelightthana40-wattbulb—theoneismorepowerfulthantheother.Similarly,amasonryheaterthatthrowsmorekWsofheatisamorepowerfulheater.SincebothunitsareoftenusedinNorthAmericaasmeasuresof

power,theyalsorelatedirectlytoeachother.Onekilowattisequalto3,412BTU/hr.OneBTU/hrequalsabout0.293watts(.000293kilowatts).Afairlylargemasonryheaterwouldoutput6kW,whichisthen20,472BTUs/hr(6×3,412=20,472).

Masonryheaterheatoutputwillbecalculatedonaper-hourbasis.Inotherwords,agivenheaterproducesacertainamountofheateveryhour,onaverage,basedonatotaldailyheatoutput.Althoughyoucouldsimplycalculateadailytotal,thehourlyaverageisamoremanageablenumberthanthatrequiredforthewholetwenty-four-hourperiod.Likewise,calculatingheatlossforthewholehousecaninvolvequitecumbersome,largenumbersifthetimeperiodislong.So,moreasamatterofconveniencethananythingelse,heatlossandmasonryheateroutputwillbecalculatedinBTUsperhourorkilowatts,unitsthatarebothusedregularlyinNorthAmerica.Muchofthischapter,then,willfocusoncalculatingtheheatingrequirements

(heatloss)ofasimplehouse.Usingtheseprocedures,andwithcarefulmathandrecordkeeping,youcandiscoverthebasicheatingneedsofaroom,severalrooms,orawholehouse.Armedwiththisinformation,youcan,withconfidence,bereadytomoveontothenextstepofdeterminingwhatkindofmasonryheaterwillmeetthoseheatingrequirements.Ifdonewell,thesecalculationswillallowanyonetoascertainwhetherornotaproposedheaterislikelytobeadequateforaspecificproject.Thelastsectionofthischapterwillprovideparametersbywhichyoucan

knowapproximatelyhowmuchheatwillbeavailablefromagivenmasonryheater.Designingamasonryheatercanbeaveryexactingscience,andthepropercalculationofeveryaspectofsuchworkisfarbeyondthescopeofthistext.Chapter8willcoverthebasicdesignparametersforagood-qualitymasonryheater.However,thereisbasicinformationyouneedinordertohaveagoodsenseofthelimitsandcapabilitiesofmasonryheaters;thesearecoveredattheendofthischapter.

BasicHeat-LossCalculations

Inordertomakethiscalculationprocesseasytofollow,we’lltakea1,000-square-foothomeofrectangularshapeasourexample.Itis25feetwideand40feetlong;itsfloorplanisshowninfigure7.3.Itswallsare10feettall,andithasaninsulatedatticandcrawlspace.I’vecreatedthisdesignwithroundnumbersandsimpledimensionstomakefollowingtheprocedureaseasyaspossible.Atthisstage,there’snoreasontogetboggeddownincalculatingwallsizeswithfractionsofafootorafewextrainches.Learningtheprocessiswhatiscrucialhere.Still,donotbedeceivedintothinkingalarger,morecomplicateddwellingisenormouslymoredifficulttoanalyze.

FIGURE7.3.Floorplanofasamplehomeforwhichaheaterwillbedesigned.

Theimportantpointistocarefullymovestepbystepthrougheachprocedureregardlessofthesizeorcomplexityofthehouse.Nomatterhowcomplexahouselooks,itstillhasallthesameingredients.Everyhousehaswalls,aroof,andafloor.Youshouldplantotackleasubjecthouseoneaspectatatime,just

asinthefollowingexample.It’salwayshelpfultonumbertheoutsidewalls.Thissamplehasjustfour.Yoursmayhavesix,eight,ten,ormore.Thenumberisirrelevantaslongasyousystematicallyanalyzeeachwallandcancompilethatdatainaneasy-to-readformat.Intheend,yousimplyaddtotalsfromeachwall,eachsquarefootoffloor,eachsquarefootofceiling,andsoontogettoatotalnumberthatwillbetheheatlossfromthehome.Alargehomewithcomplicatedlayout,oddangles,andmanyturnswilltakemoretime,butis,inreality,nomorecomplicatedtocalculate.Inaddition,somepeoplemaybeplanningonlytoheatoneorjustafew

rooms.Ifthelivingareasofthehousebeyondthoseroomsareheatedwithsomeothersource,theninteriorwallsconfiningtheareaheatedbythemasonryheaterarenotconsideredareasofheatloss.Inotherwords,ifyourgoalistohavearoomheatedtoaround68°Fandtheroomontheothersideofthewallisalready68°ormoreintemperature,it’snotpossibletoloseheattothatotherarea.(Rememberthesecondlawofthermodynamicsfromchapter3.)Forexample,supposetheplanistoheata30-foot-by-30-footgreatroomwithamasonryheater.Iftwooutofthefourwallsconfiningthatgreatroomareinteriorwallsseparatingthegreatroomfromotherroomsheatedinsomeotherway,thenthosetwowallsrepresentwallareahavingzeroheatloss.Singleroomsabuttingotherheatedareas,then,areevensimplersubjectsforheat-losscalculations.

FIGURE7.4.Oursamplehome.Itwouldbeeasytocalculateheatlossifhousesdidn’thavewindowsanddoors.

FirstPart:HeatLossbyConduction

Calculatingtheamountofheatthatislostfromahomewouldbeextremelyeasyinmosthousesifitwerenotforthefactthatwallsalsohaveopeningsinthemforwindowsanddoors.Forthemostpart,heatlossthroughthewallsthemselvesisbyconduction.Aschapter3discussed,conductionisthetransferofheat

directlythroughamaterialratherthanheattransferredbyconvection(airflow)orradiation.Whenheatlossfromahomeisduetolossofwarmair,itiscalledinfiltration.Essentially,infiltrationmeansleaks.Exteriorwallsofahomedon’tgenerallyhavesignificantinfiltration(leak)potentialunlesstheyhaveopeningscutinthemforwindowsordoors.Becausemostwallsdohavetheseopenings,itwillbenecessarytoalsocalculateorestimatelossesbyinfiltration,whichwillbedoneasaseparateoperationlaterinthischapter.Theeasiestmethod,assumingallwallshavethesamethickness,materials,

andinsulationqualities,istosimplyaddupthetotalareaofallwallsfirst,thenusethissinglenumbertocalculateheatloss.Intheprocessofdeterminingtotalarea,youmustsubtractbothwindowanddoorareasfromeachwallarea.Windowsanddoorshaveaverydifferentlevelofheattransmissionthansolid,insulatedwalls,andtheirconductiveheatlossmustbecomputedseparately.So,atthesametimethatyou’recomputingarea,youcanbeginalistofthewindowsanddoors.Asinthewall-areacalculations,ifallthewindowsareofthesamequality,oncealistismade,atotalareaofwindowcanalsobemadeforonesimplewindow-heat-losscalculation.Thissame“divideandconquer”classificationtechniqueisusefulthroughoutthewholeheat-losscalculationprocedure.

FIGURE7.5.Thecompositionofaconventionallyframedwall.IllustrationreprintedwithpermissionfromASHRAE.

Forthosewhomayperformthisanalysisonnewhomeplans,itmaybethatthedrawingsalreadyincorporatewindowanddoorscheduleslistingquantities,sizes,andqualities(ormanufacturer)ofallthewindowsanddoors.Thismakesthejobeveneasiersinceyounowonlyhavetocalculatewallareasandrefertothewindowordoorscheduletoknowhowmuchareatosubtractforeachopening.

Step1:ConductionHeatLossThroughWalls

Thebasiccalculationistofindthetotalarea(squarefeet)ofwallsurfaceandthetotalR-valueofthewall.TheR-valueissimplytheresistance(R)toheatflowthroughamaterialorassemblyofmaterials(seeappendixBforR-valuesofcommonbuildingmaterials).Itismeasuredinhr-ft2-°F/BTUs.Thearea(A)isdividedbytheR-value(R)toobtainatotaltransmissionvalueofheatthroughthatwallinBTUs/hr-°F.

A÷R=BTU/hr-°FThewallsofthesamplestructureareconventionallyframed(seefigure7.5).

Thismeanstheyarebuiltwith2-by-4studsandthewallcavitiesarefilledwithfiberglassinsulation.Theinsideofthewallsarecoveredwith½-inchSheetrock.Theoutsideissheathedwith½-inchplywood.Overthesheathingisa½-inchlayerofStyrofoaminsulationandwoodsiding.Thestructurehasfourwalls.Walls1and3areeach40feetlongand10feet

high(seefigures7.6and7.7).

40ft×10ft=400ft2×2=800ft2

However,wall1hasthreewindowsandonedoorwithatotalareaof61ft2.Wall3hasa21ft2doorandthreewindowstotaling32ft2.Thisleaves686ft2ofrealwallsurface(totalwallarea–totalwindow/doorarea=realwallsurface):

800ft2–114ft2=686ft2

FIGURE7.6.Wall1.

FIGURE7.7.Wall3.

FIGURE7.8.Walls2and4areidenticalinsize.Wall2hasnowindowsordoors,however.

Walls2and4areeach25feetlongand10feethigh(seefigure7.8):

25ft×10ft=250ft2×2=500ft2

Wall2hasnowindowsordoorsbutwall4hasoneslidingglassdoorof42ft2

andonewindowof16ft2.

Thesesidesthenhavearealareaof442ft2:

686ft2+442ft2=1,128ft2

Therefore,thetotalrealwallsurfacearea(A)is1,128ft2.

TheR-valuesforthesamplewallareasfollows:

½inchSheetrock...................00.45

3.5inchfiberglassinsulation.....12.00

½inchplywood........................00.63

½inchStyrofoam......................02.50

Woodsiding.............................01.02

Total........................................16.60ThetotalR-valueofthiswallassemblyisthetotalofallthese;(R)=16.60.Thetotalheat-losstransmissioniscalculatedbydividingrealwallsurfaceareabyR-value:

1,128ft2÷16.60hr-ft2-°F/BTU=67.95BTU/hr-°F

Therefore,thetotalconductionheatlossthroughthesewallsis67.95BTU/hr-°F.

Step2:ConductionHeatLossThroughWindowsandDoors

Therearethreedoors;oneisasolid-corewooddoorandtheothersareglassdoors.Therearesevenwindows.Inthiscase,sincethetwoglassdoorsaretheequivalentoflargewindows,thecalculationwillbebasedonninewindowswithatotalarea(A)of148squarefeet.Theremainingdooris21squarefeet.TheR-valueforthewindowsandglassdoorsis3.13(thesearedouble-pane

insulatedglassunitswithalow-ecoatingasseeninappendixB),resultinginthefollowingcalculationoftotalconductionheatloss:

148ft2/3.13hr-ft2-°F/BTU=47.28BTU/hr-°F

TheR-valueforthe1¾/.-inch-thicksolid-corewooddooris3.03,sotheequationforconductionheatlossofthisdooris:

21ft2/3.03hr-ft2-°F/BTU=6.93BTU/hr-°F

Itissignificanttonoticethatthetotalwallsurface,beingnearly1,200squarefeet,losesonlyoneandone-quarterasmuchheatasthewindowsanddoorsthatonlyoccupy169squarefeet.Inotherwords,evenmodestlyinsulatedwallsliketheselosenearlyfiveandone-halftimeslessheatpersquarefootthandohigh-quality,low-emissivitywoodwindows!Thisisafantasticargumentforonlyhavingwindowsofthehighestqualityandinasfewplacesasareneededforenjoyment,light,andvisibility.Oneoftheeasiestandleastexpensivewaystosaveenergyistoeliminateawindowinfavorofinsulatedwallwheneverpractical.Awallwithoutopeningscostslesstobuild,hasmuchlesschanceofinfiltratingair,andeliminatesanitemsubjecttobreakage,failureofoperation,andeventualcostlyreplacement.Certainlyyoudonotwishtohaveahousewithnowindows,butahousewithappropriate,carefullyconsideredglazingwillbebothmoreeconomicaltobuildandeasiertoheat.

FIGURE7.9.Thisstuccoheaterwithtiletrimfeaturesaheated“couch.”Noticethewoodstorageunderthefireboxandspecialtypicturetilesasymmetricallylocated.PhotocourtesyofBiofire,Inc.

Step3:ConductionHeatLossThroughtheCeiling

Inoursamplehome,likemanyhomes,theatticisaventedspace.Therefore,thecalculationsforheatlossdependsolelyonthethicknessandtypeofinsulationandthetypeofceilingmaterial.OtherconstructionsmayhaveacathedralceilingwithaconstructionmorecloselyrelatedtowallconstructionwithinsideSheetrock,insulation,outsidesheathing,roofingpaper,andtheroofitself.Regardless,theoverallanalysisoftheceilingis,inmostcases,simplerthanforwallsbecausetheceilingisusuallycontinuous,withnoopeningslikedoorsandwindows.Obviously,skylightsandatticaccessesshouldalsobe

considerediftheyinanywaycompromisetheoverallthermalprotectionoffered.Themodelhomeinthissamplehasaceilingspacemeasuring25feetwide

and40feetlong.Itis1,000squarefeetofuninterrupted,insulatedceiling.Itsonlymaterialsare½-inch-thickSheetrockand12inchesofloose-fillfiberglassinsulation.Sincethehousehasaventilatedattic,thespaceabovetheinsulation,althoughprotectedfromthedeleterious,heat-drainingeffectsofwind,isneverthelessatoutdoortemperatures.TheR-valuesforthecomponentmaterialsareasfollows:

½inchSheetrock......................00.45

12inchesfiberglassinsulation....42.00

Total........................................42.45

WithatotalR-valueof42.45hr-ft2-°F/BTU,andatotalareaof1,000squarefeet,theequationfortransmittedheatlossoftheceilingsystemis(A/R):

1,000ft2÷42.45hr-ft2-°F/BTU=23.56BTU/hr-°F

Step4:ConductionHeatLossThroughtheFloor

Themodelhomeinthissamplehasafloorspacethesameastheceiling,measuring25feetwideand40feetlong.Again,itis1,000squarefeetofuninterrupted,insulatedfloor.Itsmaterialsare¾-inch-thickplywoodsubfloor,¾-inch-thickhardwoodflooring,and10inchesoffiberglassbattinsulationinthecrawlspace.Liketheceiling,thecrawlspaceisventilated.Thecrawlspaceis,forallpracticalpurposes,thesameasoutdoorsminusthewind.Thereforeitisnecessarytocalculatetheresistancetoheatflowthroughthematerialsthatmakeupthefloor.Again,werefertoappendixB.TheR-valuesforthecomponentmaterialsareasfollows:

¾inchplywood.......................00.93

¾inchhardwood......................00.68

10inchesfiberglassinsulation....35.00

Total.......................................36.61

WithatotalR-valueof36.61hr-ft2-°F/BTU,andatotalareaof1,000squarefeet,thecalculationforthetransmittedheatlossthroughthefloorofthishouseis:

1,000ft2÷36.61hr-ft2-°F/BTU=27.29BTU/hr-°F

Step5:TotalHeatTransmission

Nowthattheentireenvelopeofthehousehasbeenexamined,wecandeterminethetotalamountofheatlossthroughallsurfacesofthehomeatanygiventimebyaddingalltheabovetotalstogether,anumberrepresentingalltheheatbeinglostatoncethroughthewalls,ceiling,doors,windows,andfloor.Inthiscase,

Walls+Windows+Doors+Ceiling+Floor=67.95+47.28+6.93+23.56+27.29=173.01BTU/hr-°F

Ifthisweretheendoftheprocedure,itwouldnowbeknownthat,inordertomaintaineach1-degreetemperatureaboveoutsidetemperature,youwouldneedtoinputnearly175BTUsperhourtomaintainthattemperature.Morewillbesaidaboutthislater;butnowitisnecessarytomoveontothenextmeansofheatloss—airinfiltration.

SecondPart:HeatLossbyInfiltration

The“science”ofexaminingheatlossduetoinfiltrationorleakageforayet-to-be-builthomeorroomadditionisonlysciencetoacertainextent.Itisalsoalargepartconjectureandassumption.Whenyousitdownwithasetofblueprintsforahome,therereallyisnocertaintyatallastohowwellsealedthehomewillbefromleakage.Intheend,whatwilldetermineleakageishowcarefulthebuilderiswhenitcomestocriticalleakageareasofthehome.Evenverycarefulbuildersaresubjecttomistakesoroversights.Likewise,anexistinghome’sinfiltrationlevelisoneofsuppositionandconjecture.Withallsiding,insulation,windows,doors,trim,andsoforthinplace,thereisnoobviouswaytocalculatetheheatlossbyleakage.

Itispossible,withanexistingstructure,tohaveareliabletestdonetodeterminehow“tight”ahouseis.Therearebusinessesandbuilderswhoperformwhatisoftencalleda“blowerdoortest.”Theblowerdoorisapowerfulfanassemblythatistemporarilymountedintheframeofanexteriordoorofaresidence(seefigure7.10).Theideaistohavetheentirehouseclosedinthefashionitwouldbeforwinterweather,withtheblowerdoor,whichsealscompletely,takingtheplaceofoneoftheexteriordoors.Acalibratedblowerdoortestassemblypermitsthetestertoreliablyandaccuratelymeasuretheairpressuredifferencesbetweentheinsideandoutsideofthehouseaswellasthetotalquantityofairdrawnfromthehouse.Withthehousesealed,theblowerisactivatedandthehomeisdepressurized(becausethefanisblowingoutfromthehouse).Themeasuringdevicesmonitorthepressureasitstabilizesbacktonaturalpressureconditions.Withthedatafromthistest,howmuchairleaksintothehomeinagivenperiodoftimecanbedeterminedexactly.

FIGURE7.10.Ablowerdoorassemblyinplacetochecktheleakiness(infiltration)ofahouse.PhotobyAlexandraStewart,Portland,OR.

Theoverallgoalofeitheranexactingblowerdoortestoranestimationprocedureistodeterminehowmanyairchangesperhour(ACH)occurthroughleaksintheenvelopeofthehouse.Theanalysisallowsyoutopicturetheentire

leakinessofthehomeasifitwereoneleak.Inotherwords,thetotalnumberofthevariouscracksandcrevicesthroughwhichairmightleakareaddedtogether.Forexample,astudymightshowthatthetotalleakageinahomeisequaltohavingaperfectlyairtighthomewithasingle3-inch-squareholethroughoneoftheexteriorwallstotheoutdoors.Knowingthesizeofthatholeandtheinfiltrationandexfiltrationpressuresrelatedtostackeffectpermitsthecalculationofhowmuchaircomesinandleavesthehomeeveryhourthroughthatleak.Themoretimesthatthevolumeofairinthehomeischangedorreplacedwithfreshairduetoleakage,themoreheatthatislostbecauseofthatleakage.Conversely,ahomethatis“tighter”andhaslessairchangesperhour(ACH)willbeeasiertoheat.Fortunately,asdiscussedatlengthinchapter3,sincemasonryheatersarenot

designedprimarilytoheatair,heatlossbyinfiltrationisnotasmuchofaproblem.Ingeneral,withradiantheat,you’recomfortableatlowerairtemperatures.Giventwoidenticalhomes,theonemaintaininglowerairtemperatureswillhavelesstotalheatloss.Thisisbecausethetemperaturedifferencebetweenoutsideandinsidedrivesstackeffect(seechapter5).Stackeffectisthedrivingforcebringingcoldairintothehome.Sinceairheatingisnottheprimaryobjectivewiththemasonryheater,theextraloadfrominfiltratedcolderairisoflessersignificanceintheprimarylivingspace.Thedifferenceissubtle,butevident.Thereareanumberofwaystocalculateorestimatetheinfiltrationinagiven

home.Somegivetheappearanceofbeingmoreaccuratebecausetheyinvolveminutecalculationofthelengthsofthesupposedcracksaroundvariousopeningslikewindowsanddoors.Thecracks—theexpectedpaper-thin(orsmaller)spacesthataresusceptibletoairleakage—aremeasuredandaddedtogethertogive,again,atotalsizeoftheimagined“hole”intheenvelopeofthehome.Thecalculationisfurthercomplicatedbytheneedtoexaminesupposedwindconditionsaroundthebuilding,determinewhichwallswillencounterthemostwindandhavethemost“cracks,”aswellas,additionally,theactualspeedofthewind.Ifindthiscalculationtediousatbest,andwildlyerroneousatworst,sinceitisbasedonconjectureanyway.Notall“cracks”areactuallyleaks,andthewindandweatherconditions,aswellaslocallandscaping,canchangealltheresults.

FIGURE7.11.Thismassivesoapstonemasonryheaterhassplit-rock-facedstoneaccentsandagreenserpentinearch.Noticetheshallownicheabovethewraparoundmantelandcylindricalstonewrappingthechimneyflue.Theheaterisperfectlyplacedinthemiddleoftheprimarylivingspace.PhotocourtesyofTulikiviCorporation.

Othersmaydisagree,butasuitableaccuracyanddependabilitycanbeachievedbyotherestimatingprocedures.Mostnotably,therearenowsignificantrecordsonfileoftheairtightnessofmodernhomes.EnoughcontemporaryhomeshavebeenblowerdoortestedtoprovideadatabaseofreliableinformationaboutthenumberofACHthatagivenstructureislikelytohave.Forexample,theASHRAEHandbookofFundamentalsoffersdatasuggestingthathalfofallhousesbuiltrecentlyhave0.5ACHorlessandthatthevastmajorityofthemhavearateof1orlessACH.Themoretightlyconstructedhomeshaveaslowas0.2ACH,thoughlooselyconstructedhomescanhavearatetentimesthatat2ACH.Obviously,whatisneededisforanyonedoingthisanalysistoknowwhatmakesonehousehavethemaximumtightnessandanothertheminimum.Thedatareferencedaboveindicatethatthemajorityofhomesbuiltby

reputablebuilderswhohaveknowledgeofandputintousebestpracticeswillhave1orlessACH.Thosewhoarebuildinganewhomecaninquirewiththebuilderastowhateffortstheywillbemakingtoreduceairinfiltration.Those

whoarecontemplatingamasonryheaterinanexistingbutfairlynewhomecanberelativelyconfidentthattheirsislikelythisgoodaswell.Thosewithhomesmorethantwentyyearsoldshouldbelessconfidentandbeespeciallycarefulinjudgingtheairtightnessofthehome.ArelativelyreliableestimateofACHformosthomescanbeobtainedbyusingtable7.1.TABLE7.1WinterAirExchangeRates(ACH)asaFunctionof

Airtightness

Note:Valuesarefor15mphwindandindoortemperatureof68°F.TablereprintedwithpermissionfromASHRAE.Animportantpieceofinformationnowneededistheoutsidedesign

temperature(ODT)atthelocationofthehousebeinganalyzed.TheODTistheminimumtemperatureusuallyexperiencedinthelocalewherethehouseistobebuiltorwhereitrestsifexisting.Thisinformationisusuallyavailablefromthelocalweatherservice,orseeappendixCtofindacomparablecityclosetoyourbuildingsite.TheheadingsoftheACHtablerelatetoguidelinesofhowtightthehouseis

orisexpectedtobeusingthefollowinginformation:

•Tight:Newhouseswithfullvaporretardant,nofireplace,well-fittedwindows,weatherstrippeddoors,onestory,andlessthan1,500squarefeetoffloorareafallintothiscategory.

•Medium:Mediumstructuresincludenew,two-storyframehousesorone-storyhousesmorethantenyearsoldwithaveragemaintenance,afloorareagreaterthan1,500squarefeet,averagefitwindowsanddoors,andafireplacewithdamperandglassclosure.

•Loose:Loosestructuresarepoorlyconstructedresidenceswithpoorlyfittedwindowsanddoors.Examplesincludehousesmorethantwentyyearsold,ofaveragemaintenance,havingafireplacewithoutdamperorglassclosure,orhavingmorethananaveragenumberofventedappliances.Averagemanufacturedhomesareinthiscategory.

Armedwiththisdataandunderstanding,itisnowpossibletocalculatetheinfiltrationrateofoursamplehome.Inthiscase,thesampleislessthan1,500squarefeetinfloorarea.Itisalsoanew,well-builthomewithhigh-qualitywindowsanddoors.Itisnotedherethattheaboveguidelineslistahomeas“tight”ifithasnofireplace.Keepingwithstrictterminologyandrecognizingthatamasonryheaterisnotafireplaceperse,itispossibletostillfitthisexampleintothe“tight”category.Theconcernintheguidelinesisthatastandardfireplace—anopenfirebox

thatexhaustsimmediatelyintoachimneyabove—issimplyalargeholeintheenvelopeofthehouse.Thissingle,oft-chosenamenityissowidelyrecognizedasaheatingliabilitythatithelpsdetermineifahomeis“tight”or“medium.”Owners-to-beshouldrealizethatitispossibletohaveamasonryheaterbuiltthatlikewiseleaksifthedoorsarenotgasketedanddonotclosetightlyandifthechimneyhasno100percentclosuredamper(seesidebarandfigures7.12–7.14).Consultwiththebuilderofthemasonryheatertoverifyhowtheheaterwillbe

builtinrelationtothisconcern.Thosemasonryheaterswithouttightlyclosinggasketeddoorsand/or100percentclosuredamperscanswaythehomeintothe“medium”or,possibly,the“loose”category.ThissamplehomeislocatedintheCleveland,Ohio,area.Referringto

appendixC,weseethatClevelandexperiencesawinterseasonlowof0°F.Thechartiscompiledwithhistoricalweatherdata,andtheexpressedlowsindicatethat,onaverage,thegeographicregionexperiencestemperaturesabovethattemperature99.6percentoftheyear.Inotherwords,onaverage,theregionofClevelandonlyexperiencestemperatureslessthan0°Fonlyabout0.4percentofacalendaryear.Thatrepresentsaboutthirty-fivehours;itislessthantwofulldays.Ofcourse,thisishistorical,averageddataanddoesnotmeanthatClevelandneverhad(orneverwillhave)periodscolderthanthatforanextendedperiod.However,historyshowsthatmorethanafewdaysinwhichitgetscolderthan0°Farerelativelyunlikely.

WHATISADAMPER?

Adamper,withinthecontextofmasonryheaters,isadeviceusedtodampenorreducetheflowofexhaustinaflue.Mostoftenitisinstalledinachimneyflue—though,theoretically,onecouldbeinstalledinthefluesoftheheatertoredirecttheflowofexhaustforspecificpurposes.Oftenadamperisoneoftwotypes:Sometimesit

isaslidingplateofsteelwithahandleontheendthatyoucanpushin(toclose)orpullout(toopen).Othertypesaresteelplatesthatswivelwithintheflue.Youturnthehandle90degreesonewaytoopenitandtheoppositewaytoclose.Mostdampersusedwithmasonryheatersarenot“fullclosure”

dampers.Inotherwords,bydesign,theycannotclosetheflue100percent.Oftentheyonlyclosetoabout95percent.Thisisasafetymeasure.Ifsomeoneinadvertentlyclosesthedamperbeforethefireisactuallyextinguishedinthefirebox,thepartialopeningassuresthatpotentiallylethalgaseslikecarbonmonoxidewillstillmaketheirwayupthechimney.

FIGURE7.12.Anexampleofaguillotinedamperpulledouttoopentheflue.

FIGURE7.13.Aroundstainless-steeldamperintheopenposition.Thedamperplateswivelsoutoftheway—controlledbyahandleontheshafttotheright.

FIGURE7.14.Thedamperintheclosedposition.Slotsandaloosefitmakethisa95percentclosuredamper.

Ifthedesignerusesthisdataanddesignsamasonryheaterforthislow,itisofgreatcertaintythattheheaterwillproducetheheatthehomeneedsformorethan99percentoftheyear.Shouldthataveragelowbebreached,itisunlikelythatthehomeownerswillexperiencediscomfortunlessthetemperaturefallssignificantlylowerforanextendedperiodoftime.Likewise,youcouldopttodesigntoahigherseasonalaverage,forexamplebychoosinganoutsidedesigntemperaturethatisonlybreached10percentoftheyear(aboutfiveweeks).Inthisway,thedesignedheaterwouldaccommodateallbutthecoldestmonthoftheyear.Thisisawayofdesigningtosaveexpenseontheconstructionofaheater(becauseasmallerheaterisneeded),butrecognizingthatthemasonryheaterisnecessarilysupplementalheatoranemergencybackup,notthesolesourceofheatforthespace.Thesamplehome,then,mostcloselyrelatestoahomeintable7.1thathasan

outdoordesigntemperatureof0°Fandisof“tight”description.Thehomethereforehasanexpectedinfiltrationrate,describedinairchangesperhour,of0.51.Thismeansthevolumeofairinthehomeischanged0.51timeseveryhour;thehousereceivesacompletefreshairinfusioneverytwohours.Finally,withtheACHnumberinhand,itispossibletocalculatetheamount

ofenergyrequiredtocompensateforinfiltratingairandtherebyhelpmaintainachosentargetindoordesigntemperature(IDT).ThisnumberisachievedbymultiplyingthevolumeofthelivingspacebytheACHandthespecificheatofairatstandardairpressure.(Youwillrecallthat,inchapter6,specificheatrepresentstheamountofheatthatamaterial—inthiscaseair—canhold.)Forthissampledwelling,theequationlookslikethis:

HeatLoss(byinfiltration)=SpecificHeatofAir×AirPressure×VolumeofHouse×ACH

Therefore:

HeatLoss=(.018BTU/lb-°F)(.075lb/ft3)(10,000ft3)(.51ft3/hr)=91.8BTU/hr-°F

ThirdPart:TotalHeatLoss

Nowthatafigureforinfiltrationheatlossandconductiveheatlosshasbeenobtained,itisasimplemattertoaddthemtogethertogetaquantityrepresentingtotalheatlossfromthehomedescribed:

TotalHeatLoss=InfiltrationHeatLoss+ConductiveHeatLoss

TotalHeatLoss=91.8BTU/hr-°F+173.01BTU/hr-°F=264.81BTU/hr-°F.

ThetotalheatlossisexpressedinBTUsperhourperdegreeFahrenheit.ThetermperdegreeFahrenheitreferstothedifferencebetweenthetemperaturetobemaintainedinsidethelivingspaceandtheoutsidedesigntemperaturementionedintheprevioussection.Thetemperatureinside,orIDT,isoftennamedinlocalbuildingcodes,commonlyat68°F.Absentsuchcodesorauthoritiesattemptingtoenforcethem,youshouldrelatetoexperience,bearinginmindthatradiantheatingisusuallyquitecomfortableevenwhenairtemperaturesarelowerthanusualinthevicinityoftheheater.Asageneralrule,itispracticaltousethe68°Ffigureforthesecalculations.Veryfewwouldevercomplainifthedesignedmasonryheaterwarmsbetterthanexpected,butthereverseisnottrue.Thehouseinquestion,intheCleveland,Ohio,area,experiences0°FODTand

hasanIDTof68°F.Thedifferencebetweenthetwois68°F.Tofindtheamountofheatneededperhourinthisparticularhouse,then,itismerelyataskofmultiplying68°Fbythetotalheatloss(THL):

(68°F)×(264.81BTU/hr-°F)=18,007.08BTU/hr.

FourthPart:AdditionalFactors

Thetotalheat-lossnumberpurportstoexpresshowmuchheatmustbeaddedtothelivingspaceeveryhourbyaheatingsystem.However,housesarenotdesolatespacesdevoidofallotherinputs.Theheatingsystemaloneisnottheonlysourceofheatinatypicalhouse.Electricalappliancesofallkindsalsoproduceheat,asdothepeoplewholiveinthehouse.Somemoderncomputer

andentertainmentsystemscangeneratetremendousamountsofheat,asdorefrigerators,freezers,lights,andanyotherappliancesthatrunautomatically.Inaddition,agivenhomemayhavesouth-facingwindowsthatallowwintersunshinetopenetrateandaidinwarmingthehouse.Alloftheseadditionalfactorscanbeconsideredinthecalculationprocess.

Occupants

Theamountofheatproducedbyhumanmetabolismissurprisinglyhighandshouldnotbeignoredinheatingcalculations.Ahomeownerdoingthesecalculationswillknowhowmanypeoplewillbelivinginthehome.Likewise,adesignercanestimatebasedonthedesignofthelivingspaceandnumberofbedrooms.Ingeneralitisassumedthatamasterbedroomwillusuallyhavetwooccupantsandeachadditionalbedroomwillhaveone.SincetheminimumODTexpressedearliernormallyhappensatnightwheneveryoneinthefamilyishome,itcanbeassumedthatthemaximumhumanheatinputispresentforthesecalculations.Forpurposesofheatingcalculations,itisassumedthateachpersonwillbeoutputtingatleast230BTU/hourintothelivingspace.Intheexamplehere,thetwo-bedroomhomehousesthreepeoplewhocontributeatotalof690BTU/hr.

FIGURE7.15.Eventhetelevisionandsoundequipmentinahomecontributeheat.Thisunusualplasteredheaterservesasanalmostnondescriptroomdividerbutstilloffersheatedsittingandsculpted“steps”abovethefirebox.PhotocourtesyofBiofire,Inc.

Appliances

Ifyouknowforsureofspecificheat-producingappliancesoraccessoriesthatwillalmostalwaysbeinthehome,youcanaddtheheatingcontributionofthoseitems.Inparticular,computersandhigh-amperageentertainmentsystemsandtelevisionscancontributeagreatdealofadditionalheat.Lightsthatmaybedesignedtobe“alwayson,”likeaccentlighting,canalsobereliablecontributorsofadditionalheat.Ingeneral,however,itisassumedthatdailycooking,laundry,

andarunningrefrigeratorwillcontributeapproximately1,600BTU/hr.Thisisthefigurethatisusedhereinthesamplehome.

SolarGain

Becarefulhowyouconsidersolar-heatinggainsinahome.Ifthehomeisspecificallydesignedtocollectandstoresolarenergy,itdefinitelyneedstobeconsidered.Otherhomes,however,mayreceivesomesolargainthroughwindowsduringtheday,butmaynothaveenoughthermalmassinthehometoreliablystoreanysignificantportionofthatgain.Ifparticulareffortsarenotbeingmadetostoresolargain,itisbesttodisregardthesolarinfluence.Thisistruebecauseminimumtemperaturestypicallyareexperiencedlongafterthesolargainoccurred;thecoldesttemperaturesgenerallyoccurasdaybreakapproaches—perhapstwelvetosixteenhoursafterthelastvaluablesolarinputintothehome.Thistextisinsufficienttoproperlycoverallthenecessaryinformation

regardingsolargain.However,adesignershouldbecognizantofthefactthatglass,particularlysouth-facingglass,willresultinheatgaininahouseinwinter.Ingeneral,evenincold,northernclimates,itispossibleonsunnydaystoreceiveacouplethousandBTUspersquarefootofdouble-panedglasswindows.Bearinmindthatthesewindowsdon’thavetobesouth-facing.Good-qualitywindowscantransmitevenreflectedsunlightintoahomeandresultinheatgain.Inoursamplehome,forexample,thathas130squarefeetofwindows,there

couldbesolargainofasmuchas(130ft2)×(1,000BTU/day-ft2)=130,000BTU/dayinthemonthofJanuary—thecoldestmonthinCleveland.Thereisalways,however,anabsorptionfactorgoverninghowmuchofthatenteringheatenergyisabsorbedbythesurfacesinthehouse.Ceramictilesandlight-paintedwallsmightonlyabsorb40percentofthatenergy.Inthiscase,thetotalenergyabsorbedinthewholedayis40percentofthat130,000BTUsor52,000BTUs.Dividingthattotalbytwenty-fourhoursinaday,thetotalheatgainedbysolarabsorptionthroughwindowsis2,167BTU/hr.Thereismuchmoreinformationneededtofullyunderstandandreliably

discoverthegainsassociatedwithsunthroughthewindows.Eachlocalityhasitsaveragemonthlyamountsofsolargainbasedonweatherconditions.Everyhouseissituateddifferentlyinrelationtothesun’sapparentpaththroughthesky.Differentmaterialsandsurfacesinthehomeabsorbdifferentpercentagesofthesolarenergythatstrikesthem.Allthesefactorsandmoreinfluencetotal

gains,orlackthereof,frominsolation.Thisinformationisavailablefromsourcesrelatedtopassivesolarheating,andyoushouldconsultthosesourcesformorein-depthstudy.1Ifyou’recalculatingheatlossforpurposesofinstallingamasonryheater,youmayforgothisamountofdetailunless,again,yourhomeispurposelybeingdesignedaswellforsolargain.Rarelyisoversizingamasonryheateraliability.Asalways,amorethoroughexaminationcanbeachievedbyconsultingamasonryheaterprofessionalwithmorespecificknowledgeabouthowtoproceed.

FifthPart:GrandTotalHeatingRequirements

Havingconsideredalltheforcesactingonincreasingordecreasingtheamountofheatthismodelhomerequires,itisasimplematterofadditionandsubtractiontofindthegrandtotalofheatingenergyitneedsperhour.Thestartingpointisthetotalheatlosscalculatedearlier:

(18,007.08BTU/hr)–690(occupants)–1,600(appliances)–2,167(solargain)=

GrandTotalHeatLoss(GTHL)

GTHL=13550.08BTU/hrThisgrandtotalheatlossnumberrepresentsalltheheatthatmustbe

generated,onaverage,everyhourofthedayinordertoheatthissamplehomeinCleveland,Ohio,onthecoldestdaysoftheyear.Onthedayswhenitiswarmer,whichwasdiscoveredtobe99.6percentoftheyear,thismuchheatdoesnothavetobegenerated.Again,thecalculationcouldhavebeendonetofindtheamountofheatneededtoaccommodateconditionsunderwhichonly99.0percentofthedaysarewarmer.Asomewhatsmallermasonryheaterwouldbeneededandsomewhatlesswoodconsumed.I,however,recommendthat,ifyouaspiretouseamasonryheaterasthesolesourceofheatinahome,itisalwaysbettertohavecalculatedfortheworst-casescenariothantofindyourselfdisappointedinanunusualseasoninwhichsevereweatherdropsoutdoortemperatureswellbelownormaloraverageforanextendedperiodoftime.

AWordofCautionSomereadersmaydecidethattheforegoingexamplecalculationisastrong

enoughbasisforestimatinganotherproject.Inotherwords,youcoulddecidethatsincethisexamplecalculatedtheneedsfora1,000-square-foothome,ahouseexactlydoubleinsizewithsimilarinsulationwillhavesimplydoubletheheatingrequirements.Thisisanerroneousassumption,especiallyifthegeographiclocationisdifferent.Rememberthatwinterweatherisdifferentfromplacetoplace,anddifferenthousesarebuiltdifferently.Evenwallsofthesamethicknessmayhavedifferentkindsofinsulation,subtlydifferentmaterialthicknessesormakeup,andsoforth.Itisalwaysbettertoknowthantoguess!

CalculatingHeaterSize—APreludetoChapter8

Onceyou’reawareoftheheatingrequirementsforagivenspace,itispossibletodiscoverwhatsizemasonryheateryouneedtoheatthatspace.Thatprocessstartsbysimplyanalyzingthefuel.Ifahomerequires13,600BTU/hr,asdoesthemodelexaminedintheprevioussection,itisclearthatyouneedtoknowhowmuchfuelneedstobeburnedtoproducethatmuchheat.Thenitneedstobeclearhowoftenfuelisexpectedtobeburnedinthemasonryheater.Ifaheaterisgoingtobefiredonceeveryday,itwillneedafireboxofadifferentsizethanaheaterthatisgoingtogetfiredtwice,oranotherheaterthatisgoingtogetfiredthreetimes.Finally,youneedathoroughunderstandingofthematerialsandtechnicaldesignparametersformakingagoodmasonryheater.

TheEnergyContentofWoodAnytypicalair-driedwoodcontainsapproximately6,400BTUperpound.(Air-driedwoodgenerallyhasamoisturecontentof15to20percent.)Continuingwiththescenariodevelopedintheprevioussection,theheaterbeingdesignedforthe1,000-square-foothomeinClevelandneedstoburnenoughwoodtogenerate13,600BTUperhour.Youmightjumptotheconclusionthatthiscalculationisimmediatelyverysimple.Twopoundsofwoodproducenearly13,000BTU,soyouneedtheequivalentofabout2poundsofwoodperhour,or48poundsperday.Actually,50poundsofwoodcontains320,000BTU,which,dividedby24,is13,333BTUperhour—nearlytheexactamountapparentlyneeded.However,it’snotquitethatsimple.

Efficiency

Apoundofwoodburnedatnear100percentcombustionefficiency—meaningthateveryavailablecombustibleelementinthewoodisconsumed—willreleaseabout6,400BTU.Masonryheatersgenerallydohavecombustionefficienciesapproaching100percent.Verylittlewoodiswastedwhenburnedinamasonryheater.However,thereisanotherkindofefficiencymeasurethatismorerelevantto

thequestionofhowmuchwoodyouneedtoburntoheataspecificspace:heatingefficiency.Asmentionedinchapter1,thisistheratiobetweenhowmuchheatisavailablefromtheconsumedwoodandhowmuchofthatheatactuallymakesitintothelivingspace.Thismeasureisexactlywhatseparatesagoodmasonryheaterfromasuperbone.Virtuallyallmasonryheaterswillliberatenearly6,400BTUfromapoundofwood.Somewillonlygetalittlemorethanhalfofthatheatintothelivingspace,though,whileotherswillgetconsiderablymore.FIGURE7.16.Anheirloomheaterbuiltwithwhitetiles.Soapstonetrimpieceslendsomecontrasttothiscleanlineddesign.Noticethethreeprotrudingtilesabovethefirebox.Thesearesootcleanoutdoorsheldinplacebyclaymortar.PhotocourtesyofNewEnglandHearthandSoapstone.

FIGURE7.17.Theauthorwith34poundsofoak—halftherequiredfuelforheatingthesamplehomeinClevelandonthecoldestdayoftheyear.PhotobyAaronMatesz.

Thebestmasonryheaterswillreadilyachieveheatingefficienciesof80to90percent;thevastmajorityoftheheatliberatedbycombustionremainsinthelivingspace.Medium-gradeheaterswillbeachievingefficienciesinthe70to80percentrange.Averageheaterswillproduceheatingefficiencynumbersofroughly55to70percent.Youmustrecognizethat100percentefficiencyisneverapossibilitywithawood-firedappliance.Asdiscussedinchapter6,itischimneydraft—thetemperaturedifferencebetweentheexhaustofthemasonryheaterandoutdoortemperature—thatdrivestheoperationoftheappliance.Someheatmustbeallowedupthechimneyorthesystemcannotoperate.Therefore,masonryheatersachieving80to90percentheatingefficiencyareastoundinglyhigh-efficiencyappliances.Itisnotnecessarilyapoordecisiontoinstallaheaterthathassomewhatlower

efficiency.Thinkaboutpurchasingotherrelativelydurableitems—eventhehouseitself.Veryoftenthebetterdesigns,products,andworkmanshipwillcostsubstantiallymore.Inreturn,theresultissomethingthatperformsbetter,lasts

longer,andneedslessattentionoveritslifetime.Someonewholikesmasonryheatersandwantstoinstallone,butisrelativelycertainthatthishomeisatransitionresidence—onethattheywilloccupyforseveralyearsbeforemovingontosomethingelse—mayoptforamoremoderateinvestmentinthemasonryheater.Likewise,someonewhoismainlylookingforbackupheatoranemergencyhedgemaynotbeasconcernedaboutultimateheatingefficiency.Thosewhoarebuildinganheirloomhomefortherestoftheirlives,however,maywanttoindulgeinthemasonryheaterthatwillprovideseverallifetimesofhigh-efficiencyperformance.Theywillwantonlythebest.Whatseparatesthebestmasonryheatersfromtheaverageisentirelyintherealmoftechnicaldesign.Youwillfindmorein-depthdiscussionoftechnicalaspectsofinteriorheaterdesigninthenextchapter.

HowMuchWood...Really?

Thischapterintroducedaproposedproject.Theheatingrequirementsofthatsamplehomewerefoundtobe13,550.08BTUperhouronthecoldestdayoftheyearinCleveland.Anditisnowknownthatdry,seasonedfirewoodofvirtuallyanyspeciescontainsabout6,400BTUofstoredsolarenergy.Finally,itisrealizedthateventhebestmasonryheaterwillnotgetallofthat6,400BTUperpoundintothelivingspace.Varyingefficiencylevelswillchangethat.Inthenextchapter,thisexaminationwillbeusedtocomeupwitha

completedmasonryheaterdesign.Itwilllikelyhaveanefficiencyratinginthemediumrange.Amasonryheaterthatachievesabout75percentefficiencydelivers4,800BTUofenergyfromapoundofwoodintothehome.Thereforethisparticularheaterwillrequiretheequivalentof13,550.08BTU/hr÷4,800BTU=2.82poundsofwoodperhour.Inotherwords,thismasonryheatermustconsumejust68poundsofwoodtoheatthishomeonthecoldestdayoftheyear!Formoreinformationaboutquantitiesofwood,refertochapter10.Theheatingdemandsofthehousehavebeenanalyzedandthequantityofwoodneededisunderstood.Nowitistimetocreateaheaterthatusesthatwoodandheatsthatspace.

ONTHEEDGEOFTHEGREATPLAINS

InnorthwesternIndiana,inasmalltownclosetoLafayette,homeofPurdueUniversity,therelivesafamilyoffourthatistotallyself-sufficientwhenitcomestoheat.EllenGundlach,wholecturesonstatisticsatPurdue,andErichGundlach,achemistatanearbypharmaceuticalcompany,builtamodesttimber-

framehomethere.Astheyweregettingreadytobuild,theysoughtawaytoheatthe2,000-square-foothomeusinglittlefossilfuelbutgreatsimplicity.Theylookedatgeothermalheatpumps,solarhydronics,and,ofcourse,woodheating.Afteralltheirinvestigation,theydecidedtouseamasonryheaterastheprimaryheatsourceinthehome.Erichsayshedelightsnowin“thumbingmynoseatfossilfuels!We’reveryhappywithourmasonryheater.”Althoughitwastemptingforthemtoconsidersomeofthenewer,high-tech

waysofheating,theyfinallyoptedforthemasonryheaterconceptatleastpartiallybecause,saysEllen,“therearenohigh-techgadgetstobreakdown.Withthemasonryheater,it’sjuststoneandwood.There’snothingtofail.”SuchisthesecuritysomeoneseekswhentheyplantolivetherestoftheirlivesinahomeontheedgeoftheGreatPlainswhere“itgetsquitecoldandthewindneverstops,”accordingtoErich.Hisstatementaboutthewindissupportedbythefactthat,recently,amulti-unitwindfarmwasbuiltnotfaraway.BothEllenandErichagreethattheyshareoneregretwhenitcomestothe

masonryheater:Theybothwishtheyhadhadmoremoneysothattheycouldhaveputinabiggerunitwithmoreheatedbench.TheirsoapstoneheatercomplexincludesaTulikiviTU2200withheatedbenchesthatstartonthefrontoftheheater,wraparoundtherightside,thenturntogobehinditbeforeendingatthemassive,two-fluemasonrychimney.ThesectionofheatedbenchbehindtheTulikiviseparatesthemasonryheaterfromasoapstonecookstove/bakeovencombinationinthekitchen.Thatheatedbenchbetweenthecookstoveandmasonryheatertheycallthe“heatcave.”Ellenexplainsthatitderiveditsnamebecauseitisjustbigenoughforone

person(withnarrowhips)tosit.There,theluckyonegetsheatfrombelowfromthebench,frombothsidesviathecookstoveandthemasonryheater,andfromthebackbecausethelowerpartofthechimneyiswarm.Erichsaystheyfrequently“fightforbenchspace,”thoughheconcedesthatheusuallyletsthekids,elevenandeightyearsofage,sitthere.“Moreheatedbenchwouldhavesolvedthatproblem,butourbudgetatthetimejustwouldn’tpermitit.”Ellenaddsthateverymemberofthefamily,atonetimeoranother,hasfallenasleeponthewarmbench.Inadditiontotheirdayjobs,ErichandEllenoperateafamilyfarmselling

milk,eggs,andmeat.Theyalsoplantagardeneveryyearfromwhichtheygettheirvegetables.Erichexplainsthat,withthebakeovenavailable,theyhavenowestablishedapizza-makingtraditiononmostweekends.Theirhomemadepizzas

areaboutashomemadeastheycanget.Erichmilksthecowandimmediatelytransformsitintohomemademozzarellacheese;it’saprocesshesaystakesabouthalfanhour.Meanwhile,Ellenandthekidsgathervegetablesfromtheirowngardenandchopthem.Theymakepizzasaucefromtheirowntomatoes.Whenthepizzapiesareallassembled,theybaketheminthemasonrybakeoven.Erichlaughs,“Ihavetoadmit,Iamstillguiltyofgoingtothestoretobuytheflourforthecrust!EllenkeepstellingmeIneedtostartgrowingwheat,too.”Obviously,though,withfull-timejobsandafarmtorunbesides,theyhavetheirhandsfull.Otherthantheirpizzatraditionandweekendcooking,theysaythecookstovegetsrelativelylittleusebecauseoftheirbusyscheduleandbecausetheprimarymasonryheaterdoesmostoftheyear’sheating.Erichadvisesthatanyoneconsideringheatingwithamasonryheaterdoes

havetobeawarethat,unlikemoderntechnologicalheatingsolutions,amasonryheaterdemandsthatyoustartfireseveryday.Hetakesitinstride,though.Heexplainsthatkeepingfarmanimalsmeansheisalreadywellaccustomedtojustdoingdailytaskslikefeedingtheanimalsandfiringthemasonryheater.“Onceyoustartdoingit,”hesays,“itjustbecomespartofthedailyroutineandIneverreallythinkaboutit.Ijustdoit.”Hisrewardisthathecancomeinfromdoingchoresandfindawarmplacetosit.

FIGURE7.18.Thecookstove/bakeovenunitintheforegroundgets

occasionalusewhilethemainheater,centerleft—facingthelivingroom—istheprimaryheatsourceforthis2,000squarefoothome.TulikivibyMasonryHeaterStore.PhotobyErichGundlach.

SincetheGundlachpropertyisnotheavilywooded,theyfrequentlypurchasefirewoodfortheirmasonryheater.Theydogetsomefromfriendscuttingdowntreesorotherscroungedsources,buttheystillpurchasesomeportionofwoodinmostyears.Incredibly,however,Erichrevealsthattheyheattheirhomeallyearon,“atmost,”2fullcordsofwood.“Evenwhenwebuyitall,inourareawecanheatourhomeforawholeseasonforabout$250,”heremarks.Thecookstove/bakeovenpartofthecomplexisn’tevenneededforheatmuchoftheseason,untilitreallygetscold.HecreditsthehighefficiencyofthemasonryheatercombinedwiththeexcellentinsulationofferedbyhisSIP(structuralinsulatedpanels)insulation.Ellenpointsoutthat,unlikeafossilfuelsystem,whichrequiresalifetime

commitmenttopayingwhateverfuelcostsoccur,themasonryheatercostisalmostentirelyupfront.“Weunderstoodthatweeitherpaynowforagood-qualitysystem,orwepayahighertotal[heating]costovertherestofourlives.”Obviously,theychosethemethodthatgivesthemmoretotalcontrolovertheirhomeheating.EllenandErichsuggestthatanyoneconsideringamasonryheatershould

definitelydoonething:“Getheatedbenchesnomatterwhat!Andlotsofthem!”Likesomanyowners,thefamilymakesabeelineforthemasonryheaterfirstthingonwintermornings.Theyalsoadvisethathomeownersreallyshouldputinabackupheatingsystemincasetheyhavetoleavetheirhomeforalongperiodoftimeduringtheheatingseason.TheGundlachschosetouseinexpensiveelectricwallheatersforthispurpose,butstillhavenotinstalledthem,thoughthey’velivedintheirhousesince2005.Theyalsoappreciatehavinganashdumpfromtheheaterintothebasementfoundation;itneedscleaningjustonceeveryfewyears.(ErichcleansitoutinabouthalfanhourwithaShop-Vacrepeatedlyemptied—aprocesshesaysismuchfasterandcleanerthanshovelingbyhand.)TheGundlachfamilyislivingproofthatmasonryheatersprovideasimplewaytobecomeenergyself-sufficient—evenontheedgeoftheblusteryGreatPlains.

PhotocourtesyofNewEnglandHearthandSoapstone.

W

PARTTHREE

BuildingaPieceoftheSun

ithcarefulconsiderationforlocatingapieceofthesunintheperfectspotforalifetimeofenjoyment,thedesignproceeds.Masonryheaterscanbe

virtuallyanyshape,anysize,anycolor,andanytextureimaginable.Somemasonrymaterialshaveobviousadvantages,buttheyallcanbeusedeffectively.Withthechoicesmadeformaterials,shape,andlocation,itispossibletomoveontoconsideringtheactualconstructionoftheheater.Masonryheatershavealifeoftheirown,oncetheyareputintoservice.The

lifetheyleadisentirelydependentonhowtheyarebuilt.Mostpeoplereadilyunderstandtheversatilityoftheveneer—theoutsideappearanceoftheheater.Butfewpeoplehaveanyawarenessofthework,designeffort,andintricacythatcanbepartoftheinnerlife,theengine,ofthemasonryheater.Newownersareoftenbewilderedbythequantityandscopeofmaterialsaswellasthecustomcraftingnecessaryontheinsideofamasonryheaterinordertoassurethatallthebeautifulsurfacesoutsidebecomeradiantdelights.Buildingamasonryheaterisnosmallundertaking.Whilecommon

woodstovesandnewmetalboxfireplacescanbesetinplaceinadayandfiredthenext,custom-designedmasonryheaterscantakeweekstoconstruct.Manufacturedmasonryheatersarealsoavailablethatreducethistimesubstantially—eventooneortwodaysinsomecases—butthedesignandappearancechoicesmaybemorelimited.Asalways,aprospectiveownermustconsideralltheoptionsandmakeadecisionbasedonexactlywhatitisthatwilloccupyaprominentplaceinthehouseforgenerationstocome.Itcanbeawhollyunique,one-of-a-kind,heirloomheater,oritcanbean“out-of-the-box,”manufacturedheaterwithonlytheouterskincustomizedtothehomeowners’wishes.Chapter8providesanoverviewoftheknowledgenecessarytomakethesedecisionsintelligently.Designersorbuildersofheatersneedtobealwaysrefiningskillsand

knowledgeandexpandingtherepertoireofmaterialsandtechniquestheyuseineverynewproject.Suchpersonaldevelopmentassuresthateveryheaterisbetter

thanthelastandthattheycanconfidentlyplananewprojecttoproperlyfulfillboththedesiresofthehomeownerandtherequirementsofgentleradiantheating.Withinthescopeofthatknowledge,theymustbeawareofvariouscoderequirementsateverylevelandhaveacompletegraspofpossiblewaystosupportamasonryheaterwithanadequatefoundationstructure.Homeownerslikewiseneedtobegenerallyinformedaboutwhatlimitationsexistinthisregard.Thesetopicsarecoveredinchapter9.

FIGURE8.1.Thisisthebacksideoftheheaterseeninfigures3.6and4.8.Thehandmadetilesformingthebackrestofthewoodenseatcreateapictureofspiressimilartotheactualonesthatexistoverthefirebox.Combininghandmadetileswithhandcraftedheatersmeansaninfiniterangeofpossibledesigns.Kachelofendesigned,built,andphotographedbyErnstKiesling,CanadianKachelofen.

CHAPTEREIGHT

TheInnerLife—CoresandFlues

Theterminnerlifeisaperfectdescriptionoftheinternalstructureandfunctionofamasonryheater.Manyheaterbuilderssimplycallthisthecoreoftheheater.Awell-designed,high-efficiencymasonryheateris,however,aheatermason’sattempttocreatealiving,breathing,heat-producingentitythatmimicstheveryhumansitismeanttowarm.Thehumanbodyhasaninnerlifeaswell.Theinnerlifeofahumanconsists

ofallthefunctionalelementscontainedwithintheskinofthebody.Principallytherearethreerealmsinthehumanbody:themetabolicrealm,thephysicalcirculation(rhythmic)realm,andthenervousandsenserealm.Inthebiologicalsystem,thereisnoseparationbetweenthecontainer—theskin—andtheinnerlife.Afunctioningmasonryheaterdoesnothavethemultipleintricaciesofa

biologicalsystem,butitdoesmoveandbreathe.Likealivingbeing,ittakesinfuelandusesitprimarilytoproduceheat.Whiledoingso,itnaturallymoves;itexpandsasitgetshotterandcontractsasitgetscooler.Likethehumanskin,thefacingmaterialofthemasonryheatermustbeabletomovewiththisbreathingmotionoftheinnerlife.Ifthehumanskindidnotmovewiththein-andout-breathsofthelungs,thebodywouldnotfunctionproperly;norwouldthecontainersurvive.Eventually,theskin—thecontainer—wouldbeunabletocontaintheconstant,rhythmicpressureandwouldrupture.Similarly,themasonryheaterskin(finishmaterial)canrupture(crack)ifitcannotmovewiththebreathoftheheater.Someheaterbuildersaddressthisproblembyseparatingtheinnerlifefrom

thefacing.Thisisusuallydonewitheitheraninsulation/expansionmaterialorsmall(lessthan½inch)airspace.Yetthisseemstodefeattheverypurposeofthemasonryheater,whichistoefficientlytransferheatfromtheinnerlifetotheveneerforreleaseintothelivingspace.High-efficiencywindows,forexample,useanairspacebetweentwopanesofglasstoincreaseinsulationvalue.Thequestionwemustaskis,“Whywouldwewanttodecreasetheabilityofheattomovefromtheinsideoftheheatertotheoutsidesurfaceswhereitneedstobeto

heatlivingspace?”Simultaneously,ifthereisnocontaineractuallyholdingtheinnerlife,thenit

canexpandatwillandtheretrulyisnothingtocontainit.Abiologicalsystemwithoutanintegratedcontainerofskinisnotaprettysight.Likewise,aheatercorethatisnotdirectlycontainedbytheveneercandegenerate.Sometimesthismanifestsitselfasever-wideningcracksoninteriorcomponentsoftheinnerlifeorsimplyasthegradualopeningofjoints—aslow,methodicaldeteriorationovertime.

FIGURE8.2.Theinnerlifeofthismodularheateriswrapped,permanufacturer’sinstructions,withcardboard.Veneermaterialistherebyseparatedfromtheinnerlifebya1.4-inchgap.Whentheunitisused,thecardboardwilldisintegrate,leavinga1.4-inchairgap.PhotobyWendellShort.

WHATISAFLUE?

TheAmericanHeritageDictionarydefinesflueinjusttherightway:“apipe,tube,orchannelthroughwhichhotair,gas,steam,orsmokemaypass.”Indeed,inamasonryheater,thefluesarethepassages(channels)builtintotheheaterthroughwhichallofthe

aboveexhaustcomponentstravelontheirwaytothechimneyflue.Thechimneyflue,ofcourse,isthe“pipe,tube,orchannel”throughwhichthosegasespasstofinallyexitthehouse.

Thiscomparisonofgeneralphilosophyofhowtohandletheinnerlifeisjustonedistinctionbetweenmasonryheatersbuiltwithanintegratedapproachthataskstheinnerlifeandveneertofunctionasonecohesiveunitandothersbuiltcreatingaseparationbetweenthetwo.BothtypesareviableandeffectivemasonryheatersandhavetheirplaceintheNorthAmericanmarket.Justasyoucandrivetoworkinahigh-performanceFerrariorinafour-doorHyundai,youcanheatspacewithastate-of-the-artcustommasonryheaterorabasic,mass-producedheaterofsetdesign.IfindtheintegratedapproachtobemorelikeaFerrari,thoughothersmightdisagree.Regardlessofwhichavenueyoutake,theheaterwillhaveaninnerlife—acore—thatneedstobebuilt.Togetherwiththeabovetwodifferentapproachestobuildingamasonry

heateraretwototallydifferentapproachestotheentiredesignoftheheater.Foraheaterbuiltwithapredesignedinnerlife,theformoftheexteriorsizeandgenerallayoutislargelydictatedbythecore.Inthetrulycustomapproach,thefirststepisdesigningthecontainer—theskin.Thisiswhatmakesmasonryheaterdesigntrulymagical—thepossibilityofdesigningvirtuallyanykindofshape,afterwhichtheinnerlifemustconformtothoseparameters.Again,likealivingbeingthatcanmovethebodyintoallmannerofshapes—afetalballoraspread-eaglestretch—theinnerlifeconformsandfollowstheshapeoftheouterlayer.Thischapter,then,isdividedintothreedifferentsections.Firstisabasic

outlineofonewaytodesignaheaterforaspecificspaceinaparticulargeographicplacewiththeassumptionthatitistobebuiltwiththeintegrated-container/inner-lifeparadigm.Althoughthistextcannotcoverindetailalltheaspectsofsuchdesign,itseekstoenlightenthereaderaboutthepossibilitiesavailable,theparametersdictatingdesign,andhowthedesignisgenerallyconceived.Theactualdesignandconstructionrequireagreatermasteryandunderstandingofallthevariablesinherentindesigningaliving,breathingmasonryheaterforaspecificspaceandtoaparticularperson’spreferences.Thefirstsectionisaugmentedattheendbyaphotosequenceofthe

constructionofaheaterbuiltwiththeintegrated-containerandinner-lifeapproach.Eachstepoftheconstructionisdescribedindetail.Theprojectisasimple,smallmasonryheaterincomparisontowhatispossible,andtherefore

servesasagentleintroductionintothecomplexitiesthatcanbeencountered.Everycustomheaterisdifferent.Theonefeaturedhadtomeettightparameterssetbythehomeowner.Thesecondpartofthechapterexploressomeofthemostbasiccorekitson

themarketthatcanbebuiltwithamodicumofmasonryheaterunderstanding,yetproduceveryrespectableandpredictableperformancewithgoodlongevity.Aswillbeseen,asetcore(inner-life)designpurportstoproduceaone-size-fits-allsolutiontoheatingthattakeslittleaccountofthemanyvariablesthatinfluenceperformance.Yetthousandsofpeoplelivehappilywiththeseheatersaswell.Thefinalpartofthechapterbrieflyoutlinesotherentirelydifferentsolutions

toheaterdesignandconstruction—someusingcorekitsagain,somethatarenearlyoff-the-shelf,wholeheaterpackages,andanothercompletelydifferentapproachtoheaterdesign.

CalculatingaHeater’sSize

Inchapter7,asamplehomewascalculatedtoneed13,550.08BTUsofheateachhouroftheday(onthecoldestdayoftheyear),anditwasfoundthatthisamountofheatcanbesuppliedby68poundsofwoodperdayusingaheaterthatisabout75percentefficient.Nomatterwhathouseorlivingspaceistobeheated,thecalculationsalwaysstartfromthisposition.Youmustknowtheamountofheatrequiredforthegivenspace;fromthistheamountoffirewoodfuelcanbedetermined.Theamountoffirewoodisthenaguidetothesizeofthefirebox.Thesize,height,andconstructionofthechimneyfluedeterminedbyandcombinedwiththegeographiclocationandelevationofthesitehelpdeterminetheminimumandmaximumlengthofflues.Thequantityoffuelandthecharacteristicsofthechimneywillalsorelatetothecross-sectionalsizeoftheflueswithintheheatingelementsofthemasonryheater.Thelengthofflueswillthenrelatetothechimneysize,itsstructure,andthe

sizeoftheheateritself.Obviously,iftheheateriscapableofhavingaminimumof20feetofflues,butthesizeofthemassonlyaccommodates12feetofflues,theheatermassistoosmall,andexcessiveheatwillbesentupthechimney.Ontheotherextreme,iftheheaterisonlycapableofhavingamaximumof20feetoffluesbutthereisenoughmasstoaccommodate30feet,thennotallofthe

masscanbeutilized.Thetotallengthandsizeoffluesandtheirrelationshiptotheamountofmassisoneoftheprincipaldeterminationsoftheefficiencyoftheheater.Thoseheatersthathaveonlyaveragetomid-rangeefficiencyratingsof55to75percenthavetoolittlefluelengthfortheamountofwoodtobeused,whilethosewithefficienciesapproaching90percenthaveoptimizedtheamountandsizeoffluestotheamountofmassavailable.

ASampleHeaterforaSampleHouse

Buildingonchapter7’sexaminationofaparticularhouse,hereitwillbeourtasktolookatwhatcouldbebuiltforthatspace.Havingalreadydeterminedheatloss/heatingrequirementsandquantityofwood,thenextfactortolookatisgeographiclocationfollowedbychimneyheightandstructure.

GeographicLocation

Thereasongeographiclocationisimportantisthateachareahasnotonlydifferentweatherconditions,butalsoadifferentelevationabovesealevel.Thismayseemirrelevantatfirst,butitisnot.Forexample,theboilingpointofwaterathigherelevationsislower—roughly1degreeper500feetofaltitudechange.Inotherwords,waterwillboilat212°Fatsealevel,butat1,000feetabovesealevel,itwillboilat210°.Thisisbecausetheairpressureislowerasaltitudeincreases,asseeninfigure8.3.Chimneydraftisentirelyaresultofdifferencesinairpressure.Andchimneydraftisaveryweakforce.Infact,typicalchimneydraftpressureiscomparabletothepressureasheetofpaperexertsonatable.Asgeographiclocationchanges,thedraftwillchange—aswill,correspondingly,theair-flowratetothecombustionchamber.

FIGURE8.3.Thischartclearlyshowshowairpressuredeclinesasaltitudeincreases.

Inaddition,asaltitudeincreases,theamountofoxygenavailableforcombustiondecreases.Thedesignoftheheatermustaccountforthistoassurethatthefirehasthenecessaryamountofoxygenforcompletecombustion.Insufficientairwillleadtoinefficientburnsandpoorperformance.Evensmallchangesinelevationmustbeaddressed.Forexample,Cleveland,Ohio,isat777feetabovesealevel.Clevelandisonlyabout500feetlowerinelevationthanAkron,butthedifferenceinairsupplytoamasonryheaterismeasurable.Akron,Ohioisat1,210feetabovesealevel.Generallyspeaking,thehigher

theelevation,theweakerthestrengthofdraftandtheslowertheflowofcombustionairgivensimilartemperatureconditions.Thiscombustionair-flowrateiscalculatedwithafactordeterminedbytheelevationfigure.InthecaseofAkron,withanelevationclosetozero(geodeticallyspeaking),thefactorisjustbelow1andthecombustionair-flowrateisabout78ft3/min.Atasignificantlyhigherelevation,like3,100feetabovesealevel,thisratewouldbeslower,at69.6ft3/min.Inotherwords,thecombustionair-flowrateisslowedby10percentbychangingjusttheonevariable—geographicelevation.UsingCleveland’selevation,thedifferenceismoresubtle.Thecalculatedair-flowrateinClevelandiscloseto75.9ft3/min,a3percentchangefromAkron.Thedesigneroftheheatermustcompensateforanydifferencesandintroduceacalculatedmeansofassuringthatadequateoxygenwillreachthecombustionchambergiventheslowerair-flowrateandweakerdraft.

Suchisthenatureofthistypeofcustommasonryheaterdesignprocess.Whenonevariablechanges,allothersmustchangealso,orperformance,output,andenjoymentarenotkeptatamaximum.Havingtherightheaterforaspaceismoreakintogettingacustom-tailoredsuitthanitistopickingoneupataclearancesale.Ifyoujustbuyasuitofftherackatthestore,itmayservethegeneralpurposeofclothing,butitdoesn’treallyfitright.Atailor,however,willmakesurethewaistsizeisperfectandthepantlength,necksize,shouldercut,andsoforthmakeyoulooknaturalintheclothes.Likewise,acustom-tailoredmasonryheaterfitsthesurroundingsinshape,size,andfunction.

ChimneyHeightandStructure

Ifidenticalmasonryheatersarebuiltintwoidenticalneighboringhouseswithtwodifferentchimneysystems,theheaterswillnotfunctionequallyinbothhouses,evenifthechimneysarebothlocatedinthesameroomandhavethesameheight.Forexample,astainless-steel,insulated,8-inch-diameterchimneyflueandan8-by-12clay-linedfluedon’thavethesamecross-sectionalarea.Theyalsodonothavethesamecapacitytoinsulatefluegasesorthesamefrictionaleffectongasesmovingthroughthem.Thesteelchimneywillfacilitatemorerapidmovementofhotgaseswhiletheclaywillbeslower.Thegoalistohavetheappropriaterateofmovementsuchthatthereissufficienttimefortherightamountofheattobeextractedfromtheexhaustwithinthemasonryheaterbeforeitgetstothechimney.Then,oncetheexhaustdoesmakeittothechimney,itmustbesufficientlywarmtomakeitallthewayupandoutofthechimneyfluewithoutcoolingtothedewpoint—thepointatwhichthegasescancondenseonthesurfacesofthechimneyfluewalls(above113°F).Theheightofthechimneyalsoplaysahugeroleinthecalculationofthe

heateritself.Giventwochimneysofidenticalconstruction(forexample,6-inch-diameter,double-wallinsulatedstainlesssteel),theonethatistallerwillhavestrongerdraftpressure.Iftwoidenticalmasonryheatersareput,respectively,inonehousethathasan18-footchimneyandanotherhousethathasa30-footchimney,theonewiththetallerchimneywilllikelylosemoreheatupthechimney.Somemasonryheatersarebuiltwithchimneydampersthatcanbeusedtorestrictthedraft—animperfectwaytoadjustforaheaternotreallydesignedforthesituation.Similarly,airsuppliescansometimesberestricted.Again,suchmanual“adjustments”amounttoguessesastohowtogetthebestperformanceasopposedtodesigningtheheaterspecificallyfortheon-siteconditions,includingtheactualheightandconstructionofthechimney.

FIGURE8.4.Theheightofthechimneymustbedeterminedbasedontheheightatwhichitconnectstothemasonryheater.

Asaruleofthumb,aheaterwillneeda6-inch-diameter(inside)chimneyifitsfuelloadisabout34pounds,asinoursampleheater.Alargerheaterthatusesaround40poundsoffuelperloadwillneeda7-inch-diameterchimney,andlargerheatersthatuseabout45poundsoffuelwillneedan8-inch-diameterflue.Inthesamplehomeforwhichthisdesignisintended,thechimneywillbea6-inch-diameter,double-wallstainless-steelflue.Thefluewillconnecttothemasonryheater4feetabovethefloor.Thereaderwillrecallthatthishousehas10-foot-highceilings.Italsohasasteep,12/12roofpitch,meaningtheangleoftheroofis45degrees.Thegableendwallsare25feetlong,sothelegsofthe45-degreetrianglecreatedbytheroofpitchareeach12½feetlong.Thismeansthetotalheightofthehousefromthefloortotheridgeoftheroofis22½feet.Sincethechimneyconnectionoccurs4feetoffthefloor,thetotalheightofthischimney(abovetheconnectiontotheheater)willbe21feet,6inches.(Thechimneyfluewillrise3feetabovetheridge.)

FireboxSize

Thefireboxofamasonryheaterneedstoaccommodateboththequantityoffueltobeusedandtheexpanding,hotgasesthatresultfromcombustion.Thefuelloadistheprincipalfactor.Intheexamplehere,thedesignisbasedonhavingaheaterthatgetsfired,atmaximum,twiceperday—onceeverytwelvehoursduringthecoldestweather.Itwasdeterminedthatthiswouldrequire68pounds(30kilograms)ofwoodeverydayor34pounds(15kg)everytwelvehours.Thefireboxneedstobedesignedtoaccommodate34pounds(15kg)ofwood.Thesurfaceareaofthefireboxiscalculatedbymultiplyingtheweightofthe

woodinkilogramsbyaconstantof900.(SofarIhaveusedonlystandardunitsratherthanburdenthetextwithreferencetobothmetricandstandard.However,theseheatercalculationsoriginatedinEurope,andnocurrentequivalentexistsusingstandardAmericanmeasurements.Sothecalculationsinthischapterarebestdoneinmetricunits,thoughtheanswerscanbereadilyconvertedtofeet,inches,pounds,andsoforthasneeded.)Inthiscase,900×15kgprovidesafireboxsurfaceareaof13,500cm2(2,093in2).Thisnumberrepresentsabox—acontainer—thatdisregardsanyopeningsinthefireboxlikethedooropeningortheexitforfluegases.Inaddition,itisknownthattheminimumfireboxfloorareais100cm2(15.5in2)offloorareaforeverykg(2.2lb)offuelused.Inthisexample,itmeansthattheminimumfireboxfloorsizeis1,500cm2(232.5in2).Notethat,asdescribedinchapter6,thefireboxdoesnothavetobesquareorrectangular.Forthisheater,itcouldbealmostanyshapeaslongasitkeepstothesesizeparameters.

TheThreeT’s—Time,Temperature,andTurbulence

Thefireboxisthepowerplantfortherestofthemasonryheater(andthelivingspaceitself).Itmustbesizedproperlytoachievetheresultsofclean,completecombustion.Ifitdoesn’thappeninthefirebox,itisn’tgoingtohappen!ThethreeT’softime,temperature,andturbulencearethekeytosuccesshere.Thefireboxmustalwaysbeneithertoolargenortoosmall.Ifitistoosmall,

theneededfirewoodmaynotfitand/ortherewillnotbeenoughroomfortheexpansionofhotgases.Thiswouldcausethegasestorushoutofthefireboxtooquickly—compromisingtheneedforadequatetimeforthegasestobeexposedtothehightemperaturesneeded,thoughturbulence—themixingofgasesduringcombustion—maybegood.Ifitistoolarge,thefireboxgaseswillmovetooslowlyanditmaybedifficult

toachievehighenoughtemperatures.Likewise,alarge,cavernousfirebox,asinthetraditionalfireplace,providesnoconditionsofturbulenceforthefuelandoxygentomixthoroughlyforcompletecombustion.Ingeneral,atoolargefireboxprovidestoomuchtimeandnotenoughtemperatureandturbulence.Overall,thegoalistohavethecombustiongasespresentinthefireboxforone

second.Thatisjusttherighttime.Thebesttemperaturesare1,400°to1,800°F.Turbulenceisnaturallycreatedbyhavingtheright-sizedfireboxandtherightamountofairsupplied.Therightamountofairismadeavailablethroughairinletsthatopento10to12cm2(1.5to1.9in2)perkilogram(2.2pounds)offuel

load.Thesampleheater,withafuelloadof15kg(34lb)perfiring,willneedatleast150cm2(22.5in2)ofair-supplyopening.Aholethatis3incheswideand8incheslongwouldbejustaboutright.Mostpeoplearesurprisedathowmuchairisreallyrequiredforclean

combustion.Thesefactsmakeitclearwhyitisthatbothtraditionalopenfireplacesandmetalwoodstovesrarelyburncleanly.Theformerreceiveswaytoomuchairandhasalmostnoturbulence,whilethelattergetsdampedsotightlythatithaswaytoolittleairandconsequentlynoturbulence.Inbothcases,theconditionsarenotprovidedforhigh-temperature,cleancombustion.

TheFlues

Designingthefluesisoneofthemostchallengingpartsofthedesignprocess.AsImentionedearlier,theshapeoftheoutsideoftheheaterisalreadydesignedaccordingtothetastesanddesiresoftheowner-to-be.Thedesigneroftheheatermusthavestartedsuchdesignwithabasicunderstandingofhowmuchheatcanbeprovidedtoalivingspacebyagivensurfaceareaofwarmmasonry.Nowafireboxsizeisinplace.Whatisleftistofilloutthe“body”oftheheaterwithfluesthatoccupyall(orasmuchaspossible)ofthevolumewithinthedesignedskin.Thesimplestruleforbeginningthedesignofthefluesisthattheminimum

lengthofthefluesisexpressedasafunctionof,onceagain,theweightofaloadoffuelwood.(Minimumlength=1.3ãweightofwoodinkg.)Inthecaseofthisexample,whichuses15kgofwoodperfiring,theminimumlengthofthefluesisjustover5meters(morethan16feet)offlue.Thisis,again,theminimumlengthofheat-exchangingfluesthatshouldbeusedinthisheater.Frequentlytheactualamountofflueusedismuchlongerthantheminimum—evenbyafactoroftwo!Therearemanyvariablesthataffectthisoutcome.Notonlydothesevariablesaffectthelengthoftheflues,buttheyalsoaffecttheoverallperformanceandefficiencyoftheheater.

Temperature,Speed,Distance,Volume,Friction,andAbsorption

Theprimaryfactorsaffectingtheheatingefficiencyofanymasonryheaterarethetemperatureandspeedoftheexhaust,thedistancetheexhaustmusttravel,thevolumeofspaceprovidedforthetravelingexhaust,thefrictionofthematerialsofwhichthefluesaremade,andhowwelltheheatfromthatexhaustisabsorbed(conducted)intothemasonrymass.Althoughtheseareindividualcharacteristics,theyworktogetherseamlesslyinanefficientmasonryheater

design.Anerrorindesigningforonewillinfluenceatleastoneoftheotherfactorsandthusresultinlowerheatingefficiency.Forexample,ifthehotexhausttravelstoofastthroughthefluesoftheheater,

thereisn’tadequatetimeforheattobeabsorbedbythemass.Itiscomparabletodrivingtoofastdownastreetwhilelookingforaparticularaddress;youcouldeasilymissit.Fluegasestravelingtoorapidlybypasstheabsorptioncapabilitiesoftheflueliningmaterialandcanendupleavingtown(goingupthechimney)beforetheirheatisdissipated.Thisexcessheatgoesupthechimneyandreducestheheatingcapabilityofthemasonryheater.Conversely,iftheexhaustistravelingtooslowlyinrelationtohowwellthe

masonrymaterialsabsorbheat,theexhaustiscooledtoothoroughly,tooquickly.Justasdrivingtooslowlywillmeanyoucan’tgeteverywhereyouneedtogo,exhaustthatgoestooslowlywillcooltoosoonandnotmakeitthroughalltheflues.Someofthemassjustwon’tgetwarmedmuchorenough,andtheremaynotbeenoughheatremainingtodrivechimneydraft.Thelattercaseleadstocondensationwithintheheateritselforinthechimneyflue;itmayalsoresultinaheaterthatbelchessmokeintothehouse.Theheaterinthiscasemaynevergetwarmenoughforadequateheating.Thissameeffectisachievedifthefluesaretoolong,toovoluminous,ormadeofmaterialsoffriction,thickness,orconductivityadversetoadequateabsorptioninrelationtotheamountofheatavailable.Fluesthatareinadequatelysizedinrelationtothespeedofthegaseswillnotbewarmedadequately.Ofcourse,thespeedoftheexhaustthroughthefluesisinfluencednotonlyby

thevolumeandfrictionalpropertiesoftheflue,butalsobydirectionandchangeofdirection.Warmfluegasesgoingupaverticalfluewilltravelmuchfasterthanthesame-temperaturegasesgoingdownaverticalflue.Inhorizontalrunsofflues,astraightrunoffersgreaterspeedthanarunwithmanyturns,especiallycomplete-reversal(180-degree)turns.Alltheseconsiderationsarefurthercomplicatedbythedesignoftheheater

itself.Inodd-shaped,specialheaters,theremaybeareaswhereitiseasytouseaflueofsizecomparabletoachimneycrosssection,whileotherplaceswithintheheatermaydemandheightorwidthrestrictions—orevenoddshapes.Itmaybethatacertainareamustconstrictthefluesizeinorderforeverythingtofit.Thiscanbedone,but,asalways,itchangesthedynamicsofthewholesystem;otherfluesmayhavetobeincreasedinsizetoaccommodatethechangedparametersintheconstrictedarea.

Asyoumaynowunderstand,thereisnosimplesolutiontoacustomdesign.Youmustseekanelegantsolutionthatpermitstheinnerlifetohavesuperbcontactwiththeskinandstillprovidesthecorrectspeedofexhaustforgoodabsorptionofheat,allthewhileassuringthatwhenthegasesfinallygettothechimneyflue,thereisjustenoughheatfortheexhausttomakeitallthewaytothetopwithouthittingthedewpoint.Atrulycustom-calculatedmasonryheaterisaremarkablyfunctionalworkofartandanengineeringandmathematicschallenge.Yetitsoperationissimpleandwillrequirenochimneydampers.Allitneedsintermsofhardwareisagood(properlysized)airsupplyandatight-closing,gasketeddoor.

TheDesignoftheSampleHeater

Severaltextbookswouldneedtobewrittentoencompassallthatthepreviousoutlinecovers.Indeed,tounderstandtheminutedetails,anengineeringorphysicsdegreeisprobablyafirststep.Fortunatelyforheaterbuilders,therearealreadyindividualswhoknowtheengineeringbehindtheworkingsofasuperbmasonryheaterandarewillingtoeithereducateothersorsellcomputersoftwarewithnecessaryspreadsheetsandcomputationprogramstohelpthedesignersolvethemanydilemmasthatpresentthemselveseveninsomeoftheapparentlysimplestdesigns.SomeoftheseresourcesarefoundinappendixA.

TheDesignProcessContinues

Inchapter7,wedeterminedthesizeofheaterrequiredforoursamplehouse.Usinginformationfromchapters5and6,thehomeownershadaprettygoodideaastowhatoptionsareavailablefordesigningandlocatingamasonryheater.TheheaterdesignedfortheClevelandhomehasafireboxfloorareaof1,500squarecentimeters,atotalfireboxsurfaceareaof13,500cm2(2,093in2),andspecifiedfluelengthofnolessthan5meters(morethan16feet).Itschimneyis21½feettallfromwhereitconnectstotheheaterandisa6-inch-diameterinsulatedpipe.Thechimneywillgothroughtheroofneartheridge,followingallthechimneyrules.Thehomeownerswereconcernedthatamasonryheatermighttakeupalotof

floorspaceinthismodest-sizedhouse.Witha1,000-square-foothome,thereisn’tmuchspacetospare.Theyweredelightedtorealizethatthemasonryheatercouldbeasmuchfurnitureasitisheater.Thekitchenwasdesignedwithadinettearea.Withnootherdiningroom,itwasclearthattheownerswouldalwaysneedatableandchairsinthediningareaofthekitchen.Therefore,this

heaterwillconsistofafireboxconnectedtoaflueruninabenchthatdefinesthekitcheneatingarea.Itistrulyfunctionalheatedartwork(seefigures8.5–8.7).

Thisisrealmasonryheaterdesigning.Theowners-to-beandthemasonryheaterprofessionalmustconversecarefullyaboutthedesires,needs,lifestyle,anddesignpreferences.Dotheclientslikesymmetryorasymmetry?Eveniftheythinktheylikesymmetry,aretheywillingtoexploreasymmetricaloptionsaswell?Whatspacelimitationsexist?Whatshapesandcolorsdoeseachpersonlike?Curves?Geometricalshapes?Tallandthin?Fatandsquat?Istheheatergoinginasleepingarea?Ifso,maybeitcanhaveasleepingplatform.Isitgoinginalivingorgreatroom?Maybeitshouldhavealotofheatedseating.

FIGURE8.5(left,top).Functionalart:amasonryheaterthatservesastheseatingaroundthekitchentable.|FIGURE8.6(left).Makingtheheaterfunctionasfurniturecanchangetheperspectiveofsomeonewhosays,“Ihavenowheretoputamasonryheaterinmyhouse.”|FIGURE8.7(above).Aviewofthefireboxelementthatpowersthisunusualmasonryheater.

Alwaysrememberthat,aboveallelse,amasonryheateristhewarmestspotinthehouse.Mosthomeshavenowarmspot,justblandsamenesseverywhere.Ahomewithamasonryheaterhasaplacethatinvitespeopletobewarm.Nooneeverneedfeelchillyinahomewithamasonryheater.Thedesignprocessmustdiscoverwherepeoplewillwanttobetofeelthatwarmthwhentheyneeditthemost.Thisturnedouttobeeasyforthehomeownersinthissamplecase.Thehouse

issmallandtheliving,dinette,andkitchenareasareclosetogether.Puttingamasonryheatervirtuallyanywhereinthosethreeroomswouldprovidegreatradiantwarmththroughallthemainlivingarea.Theownersrealize,however,thateverythingtheydo,theydoatthekitchentable.Whentheypaythemonthlybills,theysitatthekitchentabletodoso.Whenthekidsworkonbuildingamodelordoingartwork,theydoitatthekitchentable.Dittoforhomework.And,ofcourse,whereelsewouldthefamilymemberseattheirmeals?Theyreadthemorningpaperatthetable;theysnapgreenbeansthere;theyreadthemailthere,too.Tothem,thesolutionwasnatural:Havethemasonryheaterlocatedwhereatableandchairswouldhavetobeanyway.

FIGURE8.8.Asimpleandelegantflue-gaspatterncompletesthedesign.

Fromthatdecisioncomerepeatedsketchesanddrawingstoproduceideas—springboardsformoreideasandchoices—untilafinishedshapeisinplace.Forsomepeople,thiswillnottakelongatall.Othersstruggletofindtheshapestheylike.Thisistheeasypart.Onceashapeisinplace,thehardestpartensues:Findingtherightcolorsandtexturesmatedtothebestperformanceoptions.Peopleareamazedathowharditistoselectcolorsforsuchapermanentadditiontothehome.Ittakessometalentandcarefulobservationtodiscernwhatthebestcolorswillbeforindividuals.Then,ifthepeopleinvolvedhavevaryingopinionsaboutcolors,theywillhavetoreconciledifferencestogetafinalresult.Itcanbeapainstakingprocessandinvolvesnoticingwhatcolorstheownerschooseforotherimportantitemsintheirlives.

FromConcepttoReality

Thelastpartofthedesignprocessissolelyinthehandsofthemasonryheaterprofessional.Thechosendesignhastobetranslatedfromdrawingboardtoafunctionalheater,usingalltheconsiderationsoutlinedearlier.Oftenthiswillinvolvesometweakingoftheouterdesignaswellasaccommodatingthevariousflues.Iftheprocesshasbeendonecarefully,however,thechangesarerelativelyminorinthescopeoftheproject.

Inthissample,the13,500cm2(2,093in2)fireboxwillfitintoasmallcontainerwithaglassdoorfacingthelivingroomofthehome.Forpurposesofthefollowingdescriptions,thisglassdoorrepresentsthe“front”oftheheater;“left”and“right”or“forward”and“backward”assumethatyou’refacingthe“front”ofthemasonryheater.Theexhaustwilltakeajourneyofapproximately

24feetthroughtheflues.Thecoursebeginswithaleftanddownwardflow,followedbyanabruptmovementbackwardtoenterthebaseofthedinetteseatsupports.Fromthere,theflowfollowstheseats,justabovefloorlevel,allthewaytothepointfarthestfromthefirebox.Thenthefluegasesgoslightlyupandthencomeforwardtofollowtheseatsagainallthewaybackaroundtheradiustothechimneyarea.Thenthepathisupintotheareaabovethefireboxandthenexitingintothechimneyitself.It’sasimple,elegantdesign.Figure8.8showstheexhaust-flowpattern.

TheConstructionofaCustom-DesignedHeater

Uptothispoint,atheoreticalsimplehousehasbeenusedasamodeltoaidinunderstandingthegeneraldesignprocess—includingtheheatingneedsofthehousethroughtoacompletedheaterdesign.Now,forathoroughunderstandingoftheconstructionprocess,itistimeto

segueintorealitywithanactualproject.Noteveryprojectstartswithjustafloorplanandinfinitepossibilitiesasportrayedthroughchapter7anduptohere.Ahomeownermaywanttosetasidemeetingspecificheatingrequirementstoachieveotheraims,likeaspecificsize,style,orappearanceoftheheateritself.Thisisthecasewiththeprojectshownonthefollowingpages.Theparametersofthisprojectwereindeeddeterminednotbythesizeofthe

spaceanditsheatingneeds,butbythedesiresofthehomeowners.Ratherthanwantingaspecificheatingcapacity,thehomeownerswantedthemasonryheatertooccupyacertainamountofspaceandnomore.Iwasgivenamaximumheight,amaximumwidth,andamaximumdepthtoworkwithin.Theownersdidnotwantthisheatertobe“toobigfortheroom,”whichisapproximately15by20feet.Thislivingroomopensviaanarchwayintoalargekitchen,viaadoorwayintothediningroom,andanotherdoorleadstothefoyer.

FIGURE8.9.Thiswasthestartingpointforthemasonryheaterproject.Theheatermustfitinthespacedefinedbytheexistingstoneworkandmustnot“overpower”theroom.PhotobyPeggyBrown.

Originally,theownersheatedpartofthehousewithalittlemetalwoodstove,asseeninfigure8.9.Theclients(initially)didnotwanttoentirelygiveupthestonebaseorthestonewallbehind.Thesestonestructures,then,werethelength,width,andheightlimitations.Thefootprintisapproximately5feetwide,4feetdeep,and4feettall.Thehomeownersrequestedthatthemasonryheaterneverbehigherthantheexistingstonemantel.Similarly,theylikedthe“clipped”cornersofthestonebaseandrequestedthatthisshapebeincorporatedintothenewmasonryheater.Further,theyalsowishedthattheflueexitlocationbeunchangedfromwhatexistedforthemetalwoodstove.Andfinally,thehomeownersrequiredsymmetryinappearance;noasymmetricaldesignswouldbeconsidered.Myjobbecamemeetingtheirdesignwishesandputtingitintoapackagethatwouldprovideasmuchheataspossible.

FIGURE8.10.Thefinaldesign.Theowner,however,rejectedtheuseofwhitestuccoinfavorofsoapstoneforthebenchsupports.

Asdescribedearlier,thestartingpointforthedesignofthewholeheateristhecontainer:Whatwillitlooklike?Alltheinnerlifewillthenconformtotheshapecreated.Aftersometimeandsurprisinglyfewrevisions,anappearancewasinplace.Adrawingwasprovidedtothehomeownersandwasaccepted.Figure8.10isthedesigntheyapproved.Theprojectoutlinedwasasmallheaterwithwraparoundheatedbenches.The

bodyoftheheaterwouldbeallsoapstonewithallhorizontalsurfacesinblackgranite.Afewgraniteverticaltrimpiecesandsootdoorswouldprovidesomeadditionalcharacter.Alittle“cupola”ontopkeepstheheaterfromlookinglikejustabigbox.Originally,theverticalbenchsupports,showninfigure8.10inwhite,weretobestucco.Thehomeownerslaterdecidedtohavethesedoneinsoapstoneaswell.Withadesignfirmlyinplace,theon-siteconstructionwasstartedassoonas

allthenecessarymaterialsbecameavailable.Thefirstorderofbusinessnormallyisbuildingafoundationfortheheater(thissubjectiscoveredindetailinchapter9).Ingeneral,thesupportstructureisdesignedtofullysupportaslabofconcreteonwhichtheheaterisbuilt.Thatslabgenerallyfollowstheshapeofthefootprintofthemasonryheater,togetherwithanyextendedhearthsoradditionalmasonrytrimthatmaybedesired.Forthisproject,thesupportwasalreadyinplaceastherewasaconcreteblockstructureundertheflooralready.Thehomeownerswereunsureofitsoriginalpurpose,thoughitlookedlikethefoundationforafireplace.Floorjoistsweredoubledandextrajoistsaddedto

carrytheweightoftheheater.

FIGURE8.11.Aclose-upoftheair-intakecontrolhandle,whichwillbecarefullysetintothesoapstoneveneer.Theknobpullsoutabout1inchtoopen.

Thisheateristohaveoutsideairfedtoitthrougha6-inch-diameterduct,similartothegalvanizedductworkusedforconventionalfurnaceinstallations.ThoughIdon’tgenerallyfindoutsideairtobenecessary(seechapter9),localbuildingofficialsoftendo.Sometimesahomeownerwillrequestitaswell,despitemyrecommendations.Theairsupplywasinstalledbetweenfloorjoistsinthebasementleadingto

theoutside,whereitisscreenedtokeepanimalsout.Inlineofthatductisapivotingair-supplydamperwitharubber-gasketedsealtoguaranteenointakeofcoldairwhenthemasonryheaterisnotinuse.Theductworkelbowsupintoandnearthecenterofthemasonryheaterlocation.Theair-supplydamperisoperatedwithacablethathasbeencarefullyboltedtothewallbehindthemasonryheater.Theoperatingknobissituatedinarelativelyout-of-sightlocationnearthefloorandtowardthebackofthebench,asseeninfigure8.11.

FIGURE8.12.Theprojectunderway.Visibleisa6-inch-diameterair-supplyductatleftmiddle.Thecableattachedtothestonewallisthecontroltoopenandclosethegasketedair-intakedamper.TheworkingsurfaceiscementboardoverFoamglasinsulationtominimizeheattransfertothefloorbelow.

Thereisawood-framedfloordirectlyundertheheater,andIhadsevereheightrestrictionsasoutlinedearlier.Sotheoldstonestovebasewasremoved.Thisprovidedtheverticalspaceneededtoinstallalayerofnoncombustibleinsulationcoveredbycementboard.Thesematerialswillprotectthewoodfloorfromtheheatofthemasonryheaterforitslifetime(seefigure8.12).Thebuildingofthemasonryheater’sinnerlifeisentirelydependentonthe

constructionofthecontainerfortheinnerlife.Justasyouwouldnotpouroutwaterfirst,thenlookforacontainerinwhichtoputit,theskin—oftencalledveneer—ofthemasonryheateriswhatholdsthecoreinplace.Thisisthecasewithanymasonryheaterbuiltwiththeintegrated“no-airgap”methodinwhichtheinnerlifeisbondeddirectlytotheouterfacingmaterialforsuperiorheatconductance.Manyothercoresarebuiltwithinsulationoranairgap,anditisthenpossibletobuildthecorefirstandbuildaskinsecond,becausethetwoareessentiallyindependentofeachother.Ourprojectusestheformerapproach.(Thebondingoftheinnerlifetothestructuralveneerisbestseeninfigures8.20,8.21,and8.38.)

FIGURE8.13.Thefirstcourseofsoapstoneiscustom-shapedtofittheexistingstonewall.Thestonewallisaveneeronawood-framedwallandshouldbeinsulatedfromtheinnerlifeoftheheater.Visibleisthecircularcleanoutopeningforaccesstotheheatedbenchandtheheater’sfirstflue—adownfluefromthefirebox.

Therefore,thefirststepofactualheaterconstructionistopermanentlybuildinplacetheouterstructuralveneerwalltoaheightthatwillallowtheconstructionofinner-lifecomponentsagainstit.Howhightobuildtheexteriorbeforeworkcommencesontheinnerlifewillvaryfromjobtojobandfromonematerialanddesigntothenext.Thefirstcourseonthisprojectenclosesallthefluesoccupyingtheheated

benchesaswellasthesupportforthefireboxandmainbodyoftheheater.Theentirefirstcourseisseeninfigures8.13–8.24.Thefirebox-supportstructurealsoformsapathwayforcombustionaircomingfromoutdoorstothefireboxoftheheater.Sincetheinnerlifeoccupiesspacebelowwheretherestoftheveneerwillbebuilt,itwasnotpossibletobuildmoreoftheexterioruntiltheinner-lifecomponentswereinplace.Inadifferentdesign,2or3feetofthe“container”mightbebuiltbeforetheinnerlifeisadded.

FIGURE8.14.Skamolexinsulationcreatesthebackwall“veneer”ofthisheater,limitingheattransfertothecombustiblewallbehindthestone.Theinsulationboardissetinclaymortar.

Sincetheownerswantedtoretainthestoneonthewall,thesoapstonepieceswerecarefullyshapedtofitsnuglytotheunevenstonewall,asseeninfigure8.13.Sootdoors(cleanouts)arestrategicallylocatedtoprovideaccesstoallfluepassages.Oneofthesecleanoutsisdetailedinfigures8.15and8.16.Inaddition,becausetheexistingstoneisbuiltagainstawood-framed(combustible)wall,theheaterwill,fromstarttofinish,havestructuralinsulationboardandanairspacebetweenitandthestonewall,asseeninfigure8.14.Thesoapstoneelementsarewiredtooneanotherandtotheinsulationboard;thenthebenchfluerunsandthe

restoftheinnerlifeareconstructed.Whethertheouterfacingissoapstone,kacheln,orstucco-coatedbricks,this

generalprocedureisthesame.Thefacingpiecesarefullymortaredtogetherwithanappropriatematerialsuchasaclaymortarfortilesandbricks.Thesoapstoneinthisprojectwasmortaredtogetherwithacalcium-aluminamortar.Afterthemortarhasadequatelysolidified,thebricks,tiles,orstonesaremechanicallyfastenedtooneanotherside-to-sideandtop-to-bottom(seefigures8.17and8.28).Thesemechanicalfasteningsarethe“tendons”thatwillallowtheheatertomoveandexpandwithincreasedheat,yetwillforceitalwaysbacktoitsoriginallocationasitcools.Withsoapstone,stucco,orbrickheaters,theworkonthecoreproceedsassoonastheouterskinhasbeenmechanicallyreinforced.Withkacheln,anextrastepisneeded—therumpf(asseeninfigure6.41)onthebackofthetilewouldbefilledwithbricksandclaybeforethetilesarepinnedtogetherandtheinnerlifeisbuilt.(Seefigure8.18.)

FIGURE8.15.Theinnerlifeisbegunwithalayerof11.2-inchrefractoryplates.Thelittlesquareisacleanoutaccesscutintotheplate.Behindthesquareisthecircularopeninginthesoapstoneseeninfigure8.16.Thesquarecleanoutpiecehasashapedwirehandle,seenbentagainsttheinsidehere.

FIGURE8.16.Aviewofthesamecleanoutseeninfigure8.15,thistimethroughthesoapstoneopeningasyouwouldseeitaftertheheaterisdone(minustheeventualsootdoor).

FIGURE8.17.Alltheplatesandbricksoftheinnerlifearesetinclaymortar.Piecesareconnectedwithrigid,spring-steel,U-shapedclips,servingastendonsholdingeverythingtogether.Heatwillmakethepiecesexpandandwanttopushoneanotherapart.Theclipsassurethattheyremainintheiroriginalpositionastheycool.Mechanicallyjoinedpiecescanneverfalloutofplaceevenafteryearsofexpansionandcontraction.

FIGURE8.18.Heretherumpfsofstructuralheatertiles(kacheln)fromadifferentprojecthavebeenfilledwithlargepiecesofrefractoryplatesandclaymortarpriortosettingtheinnerlife.Fillingthis

wayaddsmassandcontinuestheuninterruptedmeansofheatconductionfromtheinnerlifeoutward.Theunfilledrumpfofthesesametilescanbeseeninfigure6.41.

Theinnerlifeisbuiltentirelywithhigh-qualityrefractorymaterials(firebricksandsimilarresources;acollectionofbrickscanbeseeninfigure8.19).Amasonryheaterismeanttolastlifetimes,soyoushouldnotscrimponqualityforthesepiecesthatwillconstantlycyclebetweenhotandwarmfor,potentially,alifetimeormore.Inthisproject,alltheinnerrefractorycomponentssubjectedtoexhaustaremadeforhigh-heatuse,ratherthanthecommonfirebrickoftenfoundinbrickyards.Commonfirebricksareusedonlyinlow-stressareasawayfromexhaust.Thesematerialswerepurchasedatrefractorysupplyhousesorfirmsspecializinginrefractoryconstruction.Figures8.20–8.23showthe“filling”ofthisshortcontainerwiththeinnerlife.

FIGURE8.19.Apartialpalletofheatermaterials.Standingontopisthesoapstoneandalltherefractoriesusedtobuildthischapter’sproject.Fromlefttoright:23.8-inchsoapstone;11.4-inchrefractoryplate;11.2-inchrefractoryplate;21.2-inchrefractoryplate;21.2-inchfirebrick;and2-inchfirebrick.Thethinnerplatesare12inchessquarewhilethe21.2-inchplateis12by24inches.

FIGURE8.20.Thebasecourseofsoapstoneisinplace,asisthefirstcourseoftheinnerlife.Thisfirst

courseoutlinestheheatedbenchandflues3through9oftheheater—approximately12linearfeetofflues.Theexhaustwilltravelfromtheupperleftofthepicturecounterclockwisetotheupperrightthroughthisbench.

FIGURE8.21.Thesupportstructurefortherestoftheheaterisbuiltinsidethecontainer.Theinnermostrectangleroughlyoutlinesthefireboxfloortobebuiltaboveit.TheL-shapedpiecesbegintooutlinetheair-supplyslottothefirebox.Noticethatallplatesliningthebenchfluesare“backedup”byadditionalbricksorplates.Inexpensivetilewasusedtolinetheflooroftheflues.Everythingwassetinclaymortarandpinnedtogether(thoughsomepiecesarenotyetpinnedinthisandthefollowingfigure).

FIGURE8.22.Aperspectiveviewofthebasecourseoftheinnerlife.Thetwoparallelplatesbehindthesupportstructuremarkthebeginningofthetwoverticalfluesthatarelocatedbehindthefirebox.

FIGURE8.23.Twolayersofplatesoverthebasecoursefurtheroutlinetheinnerlifeandformastructureonwhichtobuildtherest.ThebenchfluesarebeingcappedwithSkamolextoreducethetemperatureofthebenchslabs.Notetheskewcutsonthefirstlayerofhorizontalplates.TheskewsupportstheSkamolexwhileprovidingasurfacethatispartiallycantileveredoverthebenchfluestocatchboththegranitebenchstonesandthesoapstoneveneeroftherestoftheheater.

Noticethatthesizeoftherefractoryelementsusedtolinetheflueschangesastheflueproceeds.Forexample,infigure8.21,therefractoryplatesbondedtothesoapstoneontheleftare1½inchesthickwhiletheonesonthefarrightare1¼inchesthick.Asmentionedearlier,acarefullycalculatedheaterwilltakeintoconsiderationchangesinpressureandtemperatureasexhaustgasesmaketheirwaythroughthesystem.Sincealltherefractoryelementshaveroughlythesameheat-transferproperties,andoneofthegoalsofgoodheaterdesignistohaveexteriorsurfacetemperaturesasuniformaspossible,thinnermaterialsareusedasyouworkfartheralongthefluelength.Thisis,ofcourse,somewhatlimitedbywhatmaterialsareavailableintheNorthAmericanmarket.InEurope,wherethereisamany-centuries-oldmasonryheatertradition,manymoreshapesandsizesofrefractorycomponentsareavailabletothosewhobuildmasonryheaters.Theinnerrefractorybricksarebondedtotheinsidefaceoftheveneermaterial

withclay,then,likethefacingitself,aremechanicallyfastenedtogether.Theinnerlifelinesthewholeskinoftheheater,butworkonthecorealwaysstopsbeforeitisashighastheouterveneer.Thisisbecausethenextlayerorcourseoftheveneerwillhavetobemechanicallyjoinedtothecoursebelow;thiscannotbedoneifconstructionoftheinnerlifehasproceededtoofar(seefigure8.28).

FIGURE8.24.Theentiresetofbenchfluesiscapped,andthefirstcourseofmain-bodysoapstoneisbuilt.Theshorterpieceatfrontcenteristhebaseofthedooropening.Thesoapstoneoverhangsthepiecesonwhichitrests,forminganotchforinsertingthegranite,whichwasnotyetavailableasthisstagewasreached.

Sincethebenchesareonlyonecoursetall,theinner-lifeconstructionproceedstothetopofthebenchcourseandfirebox-floorlevel.Normally,thebenchslabswouldbeinstalledatthispoint,butadelayintheirproductionmeanttheconstructionproceededwithoutthem.Anotchatthebaseofthefirstshortcourseofsoapstonewillaccommodatethegraniteslabswhentheybecomeavailable(seefigure8.24).Completed,theheatedbenchesofthislittleheaterhaveapproximately11linearfeetofhorizontalflues.Thewholeheater,whendone,willhavemorethan20feetofinternalfluesandisdesignedtoconsumeamaximumofonly28poundsofwoodperfiring.Next,itistimeforthesoapstoneskinoutsidethefireboxtobeconstructed,as

seenstep-by-stepinfigures8.25–8.27.Onceagain,thesoapstoneisinstalledfirstandreinforcedasbeforewithmetalfastenings.Inthislittleheater,theupperpartoftheheatermainlyhousesthefireboxandjustacoupleoffluesaboveandbehindit.Figure8.27showsasignificantairgap(about2inches)betweenthesidewallsofthefireboxandthesoapstoneveneer.

FIGURE8.25.Followingtherulethatthecontainerisbuiltfirst,thenextcourseofsoapstoneiserected.Notethecontinuingbackwallofinsulationboard.

FIGURE8.26.Aviewintothecontainer.Thecleanerplatesformingasquareinthemiddlearedry-setfireboxfloorelements.Thefloorwillbetwolayersthatarebothsetdry.Theseremovablepiecesallowaccesstocleantheair-supplyareathatwill,overthecourseofayear,accumulatesomeash.Thetworearfluesarewelldefinedhere.

Unlikethesmall(½inchorless)airgapmentionedearlierinregardtomanymanufacturedcores,thisgapisabout2inches.Thisspaceislargeenoughtobecomeasourceofconvectionheattohelpwarmtheoutersoapstone.Airisheatedbythefireboxmaterialsandrises,thencoolsasitexchangesitsheatwiththemuchcoolersoapstone.Simultaneously,thehotfireboxcomponentswillsendradiantheatdirectlytothesoapstone.Whilemostoftheheaterconstructionhasnoairgapandoutermaterialsareheatedbyconduction,inthisregionthesoapstoneisheatedbyconvectionandradiation.Thedeparturefromtheruleofhavingnoairgapatallistrumpedherebytheneedtokeepthefireboxatitsoptimumsize.Ontheotherhand,makingthefireboxwallsverythicksothattheydid,indeed,contacttheoutersoapstonewouldcreatetoomuchmassfor

good,responsiveheattransfer.

FIGURE8.27.Alargeairgapbetweenthecontainerofsoapstoneandthefireboxwalls(orfluewalls)permitsconvectiveinadditiontoradiantheatingoftheexterior.Asmallairgapof1.4to1.2inchwould,instead,serveasinsulationagainstheattransfer.

FIGURE8.28.Thebackside(inner-lifeside)ofthesoapstone,showingmetalclipsbindingthestonetogetherbothhorizontallyandvertically.

FIGURE8.29.Thestartofthe“outburn”fromthefirebox,whichistheexitfromthefireboxintothefirstverticalflue.Theskewcutsdirecttheexhaustofthefiretothefluethatissnuglybuiltintothebackleftcorneroftheheater.

Oncetheuppercontainerofsoapstoneandinsulationboardiscompleted,thefireboxitselfandthefluesbehinditareconstructed.Inthebackofthefirebox(combustionchamber)youcansee,infigure8.29,the“outburn”orexitfromthefireboxleadingtothefirstflue—adownwardpassageconnectingtothealready-constructedbenchflueruns.Alsoinevidenceinfigures8.32and8.36,isthegasslot,whichisasmallbutdirectconnectionofthecombustionchambertothechimneyconnector.Thegasslotassuresthattherecanneverbeanaccumulationofcarbonmonoxideintheheatershouldsomeoneshutdowntheairsupplybeforethefireiscompletelyfinishedburning.Thegasslot,likemostotheraspectsoftheheater,issizedaccordingtotheamountoffueltobeusedintheheater.

FIGURE8.30.Theinsulationboardiscutaroundthestainless-steelflue.Inthisproject,an

uninsulatedmetal8-inchfluewasrelinedwithaninsulated6-inchflue.

FIGURE8.31.Anotchatthecorneroftheoutburnwillaccepttheliningofthefirstflue,yettobeplaced.Thenotchguaranteesthattherefractoryliningcanneverfalloutofplace.

Thefireboxceilingconsistsoftwolayersofmaterial,asseeninfigures8.35and8.37.Firsttogoonisasheetof“hotface”insulation—noncombustibleinsulationmaterialthatcanbeexposeddirectlytofire.Theapplicationofinsulationhereisdesignedtomaximizefireboxtemperatures.Sincehighcombustiontemperaturesarethekeytocleancombustion,thisistheoneplacewithinamasonryheaterthatreallybenefitsfromthismaterial.Theinsulationherewillguaranteerapidincreaseinfireboxtemperaturesatstart-upandconsistentlyhightemperaturesthroughoutthecombustioncycle.Oncetheinsulationboardisinplace,asolidrefractorycap,2½inchesthick,isinstalledaboveit.

FIGURE8.32.Thecompletedfirebox.Visiblejustinsidethedooropeningistheair-intakeslotthatlaterwillhaveacover/deflectorbuiltoverittokeepoutashandcoals.Inthemiddlebackofthepictureisthelittlegasslot—adirectconnectiontothefluetoguaranteenocollectionofflammable

gases.Theoutburniscomplete,andthedooropeningisbeinglinedwithrefractorytoprotectthesoapstonefromdirectheatfromflames.Notethatallinnerandouterfireboxslabsarepinnedtogethertocreateafullyintegratedassemblythatwillstaytogetherunderexpansionandcontraction.

FIGURE8.33.Aviewoftheupdraftverticalchannelcomingfromtheheatedbench.Notethecornersofthemiteredrefractoryplatesvisiblejustundertheopeningofthesteelflue.Again,miteredjointsassurethatthepartsofthefluecannotfallinwardduringexpansionandcontraction.Pinsorclipsareunnecessarywheresuchamechanicalpreventivemeasureistaken.

FIGURE8.34.Afull-planviewofthecompletedfirebox,tworearverticalflues,theoutburn,thegasslot,andflueexit.Notethe2-inchairspaceoneithersideofthefirebox.Thislargespaceprovidesenoughvolumethataconvectiveheattransferwilltakeplacebetweenthehotfireboxwallsandthesoapstoneveneer.

FIGURE8.35.Thefireboxandfirstfluearecoveredwith“hotface”Skamolexinsulation.Insulatingtheceilingofthefireboxensuresthathighcombustiontemperaturesaremaintainedformaximumcombustionefficiencyand,therefore,cleanemissions.

FIGURE8.36.Aviewthroughthefireboxdooropening.Visiblearetheinsulationboard,thegasslotandfluebehind,andtheoutburntotheleft.Notehowthesoapstoneatthedooropeningisfullyprotectedfromintenselyhotfiresbyrefractoryplatesthatcreateanopeningslightlysmallerthanthesoapstoneopening.

FIGURE8.37.Thick21.2-by-12-by-24-inchrefractoryslabscovertheinsulationboardandwillcreatethesurfaceonwhichtheupperfluesarebuilt.Theseslabsdonotrestontheinsulationboard,whichissetdry(withoutmortar).Theslabsspantheinsulationandrestontheotherfirebrickpiecespinnedtogetheroneithersideoftheinsulationboard.

Figures8.30–8.40showthedetailsoftheinnerlifeasitprogressesalongsidethefirebox,whichisshownfullycappedoffinfigure8.40.Figure8.37alsoshowsthelastmajorcourseofsoapstoneinplace.Thesmaller“cupola”shownintheoriginaldesign(figure8.10)containsnoactivefluesandisonlydecorative.Atthispointallthatisleftistocompletetheinnerlifeabovethefirebox.Thesoapstoneskinisonceagainlinedwithrefractoryplatessetinclaymortarandpinnedtogetherasseeninfigure8.43.

FIGURE8.38.Theentireinnerlife,wheneverpossible,isbuiltdirectlyagainsttheexterior“container”ofsoapstone,assuringidealheattransfer.

FIGURE8.39.Notepinsholdingsoapstonetosoapstone,insulationboardtosoapstone,anda(difficult-to-see)miteredcorner—allprecautionstokeeptheinnerlifeandthecontaineroperatingtogetherlikeonelivingbeing.

FIGURE8.40.Thecompletedcapoverfireboxandflues.Clayjointsthroughout.Noteanothernotchatmiddlerighttocaptureaplatefromthatverticalflue.

FIGURE8.41.Therightrearcorner(verticalflue).Moreinsulationboardprotectsthestone-coveredcombustiblewallbehind.Asawnnotchwillcaptureanotherplate.Notealsotheskewcutonthelowerrightofthepicturetoaidtheflowofexhaustintotheupperflues.

Theremainingfewfluesareassembledontopofthesolidcap,asseeninfigures8.45–8.48.Theyformthefinalconnectiontothechimneyconnector.Youcanseethewaysomepiecesarecutwithaskeworangletobenefittheflowofgasesaroundcornersontheirwaytotheheaterexit.Thelastfluepassagesarecappedwithsolidrefractory.Thefinalexteriorcaps

ofgraniteandsoapstonewillbebondedtothislayerofclaypargedrefractorythatisshowninfigures8.49and8.50.Theclayservesasextrabondingandasealagainstexhaustleakageovertheheater’slifetime.Onceagain,thereisnoinsulationorairspace(airgap)separatingexteriorstonefrominteriorcomponentswheneverpossiblesothatidealheattransferoccurs.Airspaces,whentheymustoccurforspecificreasons(astheydidoneithersideofthefireboxinthisheater),aremadelargeenoughforconvectiveheattransfer.Here

atthetop,theinnerlifecanagainbeintegralwiththeskin.Thisallowsthetoptobeyetanotherradiatingsurfaceofthismasonryheater.

FIGURE8.42.Anotherskewcutaidsthefinalexhausttriptothechimneyconnector.Thechimneyconnectorhasbeencarefullyinsulatedtosealtightly.

FIGURE8.43.Thecontainerhasbeenlinedwithmorerefractoryplatespinnedtogetherandclaymortareddirectlytothesoapstone.Visiblepencilmarkingsindicatecentersofflueandlocationsofremaininglinings.

FIGURE8.44.Aviewoftheheaterinprogress.Thesoapstone“container”iscompletehere.Alloftheinnerlifeiswithinwhatisshownhere.Thecleanoutopeningswillhavecustom-madegranitecovers,andtheskewedcornersarepreparedforthickgraniteinlays.Granitebenchslabswillslidepartiallyunderthefirstcourseofsoapstone.

FIGURE8.45.Thelastfluesareinplace.Theexhaustcomesupthebackright(afterexitingthebenchflues).Thegasestravelclockwisetogettotheflueexit.Thediagonallyplacedplateintheupperleftwasnecessarytomaintainappropriatefluegasspeedbymaintainingasmallerfluecrosssection.

FIGURE8.46.Adetailviewshowsthefinalpiecesmortaredandpinnedtogether.Moredifficulttoseeisthehalf-lappedjointintheupperrightlockingpiecestogethermechanically.

FIGURE8.47.Anotherviewoftheupdraftflueshowinginsulationboard,half-lappedjoint(lowerleft),andskewcut.

Sincethisparticularheaterisshortandthetopiseasytoreach,thefinal,topmostcapofgraniteonthecupolawillberemovabletoaccessthecleanoutdoorscutintothetopoftherefractoryslabsaswellastoaccessthecleaningofthechimneyconnector.Thetopcleanoutdoorsmortaredinplacewithclaybutnotpargedcanbeseeninfigure8.50.Theyhavearingofsteelasahandleforremovalandreplacementwhentheinsideoftheheateriseventuallycleaned.Withinnerconstructioncomplete,thedoorisinstalledasseeninfigure8.51,

andcustom-madesootdoorsarefabricatedandputinplace.When,atlast,thegranitebecameavailable,thebenchesandtheotherhorizontalsurfaceswerelaidinabedofclaymortar.Theconstructionsiteiscleanedandthecustomersmovebackintothelivingspace.Thismasonryheater,asshowninfigures8.52and8.53,isfinishedandreadyforgenerationsofwarmth.

FIGURE8.48.Anexhaust-gasviewofthefinaltriptothechimneyconnector.Intotal,thislittleheaterthatisnoteven4feettallcontainsmorethan19feet,6inchesoflinearflues.

FIGURE8.49.Theinnerlifeiscappedwith11.4-inchrefractoryslabs.Themiddleslabisfullysupportedfrombelow,buttheothersarenot.Theskewcutswillprovidestructuralsupportasneeded.Attopisacleanoutaccess.Again,skewcutswillguaranteethatthecleanout“door”canneverfallintotheheater.Gravityandclaymortarwillguarantee,aswell,agas-tightseal.

FIGURE8.50.Onceallthecapsareinstalled,theentire“lid”ispargedwithclaymortarreinforcedwithfiberglassmesh.Themeshisagaincoatedwithclaytomakeasolidclaysealatthetopofthemasonryheater.Themeshisareinforcementtoaddstrengthtotheassembly.Twocleanoutdoorsaresetinplacewithclaymortarbutleftfreeofclayovertheirtopsforfutureaccess.

FIGURE8.51.Adoorisinstalled,andtheheaterisreadyforgranitebenches,trim,caps,accents,andfinalcleanup.FIGURE8.52(right).Thecompletedsoapstonemasonryheater.Notethegranitebenches,cleanoutdoors,inlays,andcaps.Thetopmostcapissetwithoutmortartoprovidelifetimeaccesstothecleanoutsontopoftheheater.

FIGURE8.53.Theheaterinitsfinalsetting.Whenthisphotowastaken,theheaterhadbeeninregularuseforslightlymorethanaweek.Justpriortolightingasmallfireforphotos,theheaterwascheckedfortemperature.Thebenchsides,benchtops,andverticalsidesofthemainbodyoftheheaterwereuniformlyabout135°F;theleftrear(wheretheexhaustfirstexitsthefirebox)washigherbyabout25°.Allthetophorizontalpieces,bothsoapstoneandgranite,wereuniformlyatabout110°.Thesemeasurementsweretakenaboutthreehoursafterthemorningfire,whichconsumedjust28poundsoffuel.

PremanufacturedMasonryHeatersandCoreKits

InhisautobiographyMyLifeandWork,HenryFordwrote,“Iwillbuildacarforthegreatmultitude.Itwillbelargeenoughforthefamily,butsmallenoughfortheindividualtorunandcarefor.Itwillbeconstructedofthebestmaterials,bythebestmentobehired,afterthesimplestdesignsthatmodernengineeringcandevise.Butitwillbelowinpricethatnomanmakingagoodsalarywillbeunabletoownone—andenjoywithhisfamilytheblessingofhoursofpleasure....”1Hisideawastoproduceamodeoftransportationthatcouldsuitablybeusedbybothindividualsandfamilies—asinglesolutiontoeveryone’s

transportationneedsatapriceeveryonecouldafford.ItwouldseemthatthoseinNorthAmericawhoareproducingmanufactured

coresformasonryheatersmayhaveasimilardream.Byproducingasingledesignofmasonryheater,therearenocomplexcalculationstodooncethefirstisdesigned.Theheaterisbigenoughforfairlylargespacesyetnottoobigformanysmallerones.Iftheproducerofthecoreisalsothebuilder,hebecomesadeptandhighlyefficientatbuildingthesameheatertimeandagain.Thecomplexitiesarediminishedasthesame“problems”areencounteredeverytimethesameheaterisbuilt,tothepointthateveryproblemisforeseeableand,thus,nolongeraproblem.It’sasinglesolutiontotheheatingneedsofmanypeople.Likewise,anaccomplishedcoredesignerwithmuchconstructionexperience

canwriteamanualalertingfirst-timebuilderstoallthepotentialdifficultiesandprovidingstep-by-stepinstructions.Withstep-by-stepinstructionsandproblemspre-solved,virtuallyanyonewithamodicumofmasonryexperiencecanbuildtheModelTofmasonryheaters—aone-size-fits-allheat-storagefireplace.HenryFordalsosaid,“Anycustomercanhaveacarpaintedanycolourthathewantssolongasitisblack.”2CurrentlyintheNorthAmericanmarket,therevisedquotemightread,“AnycustomercanhaveanykindofmasonryheaterhewantsaslongasitisofFinnishdesign.”CurrentlytheFinnishdesignpredominatesinthepremanufacturedcoreandheatermarket.TheFinnishdesign,oftencalledtheFinnishcontraflow,isbasicallya

downdraftfireplace.Thismeansthat,likeatraditionalAmericanfireplace,theexhaustinitiallyleavesthefireboxandgoesthroughathroat.Inaconventionalfireplace,thesmokethenencountersalargercavityatthesmokeshelfbeforeitcontinuesupwardtoexitoutthechimney.InaFinnishcontraflow,whatmighthavebeenthesmokeshelfareaisoftencalledthesecondarycombustionchamberand,insomeversions,doublesasabakeoven.TheFinnishdesigndoesnotallowthesmoketothenescapeupthechimney.Instead,itmustfirsttakeadownwardpath(adowndraft)alongbothsidesofthecombustionchamber,toaboutfloorlevel,beforeitentersachimneyandactuallyexitsthesystem,asseeninfigure8.54.Thus,thisdesignisbasicallyasimplemodificationofaconventionalfireplace,incorporatingdowndraftsoneithersideofthefirebox.Hotairrises.TheFinnishdesignseekstocapitalizeonthisfactbyintroducing

adownwardpaththathotairdoesnotwanttotake.Theideaistotraphottergasesintheupperpartoftheheaterwhilecoolergaseswillmoreeasilybecarriedbydraftoutofthesystem.Asthegasesmovethroughthechannels,their

heatistakenupbythewallsofthedowndraftfluessothattheexhaustissignificantlycooledbythetimeitreachesthechimney.Thewholemassbecomesaneffective,warmradiantfireplace.

FIGURE8.54.InaFinnishcontraflowdesign,theexhausttravelsupthroughathroatintoasecondarycombustionchamberthenflowsdownward,typicallyonbothsidesoftheheater.Thenthesmokeexitstoachimneyconnectoratthebase.Inthiscutawayphoto,onlyonesidecanbeseen.PhotocourtesyofTulikiviCorporation.

TheFinnishcontraflowconceptholdsanattractionformanyforthesimplefactthatitseemstojibewithAmericansensibilitiesaboutwhatafireplaceshouldbe.Ittendstohaveadoorcenteredonthemassandanuprightappearance.Itisoftenoutfittedwiththelargestdoorpossible,coincidingwithmanypeople’sdesiretohavealarge,cavernousfirebox.Manymasonsveneerthepredesignedcorewithcommonbrickorwithvariouskindsofnaturalstoneyoumightseeontraditionalfireplaces.Oftentheheaterisalsooutfittedwithamantelabovethedoor.AlltheserecognizablefeaturesmakethiskindofmasonryheaterattractiveintheNorthAmericanmarket.

FinnishContraflowKits

Owingtoitspopularity,itisnosurprisethatseveralmanufacturersofcoresofthisdesignexist.Followingarethreewell-establishedproducersofsuchcores.Thereareothersaswell.Somecoreproducersdidnotwishtobementionedinthistext;otherindividualsorcompaniesmaketheircoresmainlyfortheirownuse.

TheAlbie-Core

AlbieBarden,coauthorofFinnishFireplaces:HeartoftheHome,isoftencreditedwithbringingtheFinnishcontraflowheaterdesigntotheNorthAmericanmarketdecadesago.Formanyyears,hefacilitatedworkshopsbuildingsuchheatersstrictlywithfirebricks,clay,refractorymortar,andcommonmortar.Ashemovedfirmlyintothemasonryheaterbusiness,Mr.BardendevelopedasimplebutelegantcorekitthatpermitstheconstructionoftheinnerlifeofaFinnishcontraflowheaterwithaminimumofbrickcuttingandaminimumoftime.AlbiefoundthenameAlbie-Coreamemorableandhumorousplayonthenameofawell-recognizedtunavariety.TheAlbie-Corefeaturesseveralelementscastoutofrefractoryconcrete,as

seeninfigure8.55.Mainly,Mr.Bardensoughttocastpiecesthatotherwiseinvolveagreatdealoftimeatabricksawduetomanyanglesandspecialshapes.Notablearethefirebox-floorelementsthataredesignedtoslopetowardacentralgrate—aidingtheconsolidationofembersandcoalsintoapileovertheprimaryairsupplyforrapid,cleancombustionasthefiringprocessconcludes.Thiscoredesignalsofeaturesasetofdry-set,removable/replaceablethroatelementsabovethefirebox(seefigure8.56).Onceagain,theseangledelementsreplacelaboriousanglecutsandmortaredbricks.Andsincesomanypeopleinterestedinthisdesignalsoliketheideaofthebakeoven,thecorekitincludesarchedelementsforanovenceilingaswellasalinteloveranarch-topovendoor.

FIGURE8.55.TheAlbie-Corecompleted(left)anditscomponentcastpiecesingray.IllustrationcourtesyofMaineWoodHeatCompany.

Thebasicversionofthiscorekitcreatesaready-to-veneerinnerlifethatis27inchessquare.Thekitintentionallydoesnotincludeprecastheat-exchangechannelsforseveralreasons,includingthefactthatveneerbricksareavailableinmanysizes.Bybuildingthefluesonsite,youcanaccommodatepreciselywhateversizebrickshavebeenchosenfortheexterior.Thiskitisavailableorcapableofbeingmodifiedtomakeasee-throughfireboxunit,adouble-downdraft“supersized”Albie-Core(4½inchesdeeperandmuchwider),acornerunit,and(ofcourse)both—withorwithoutabakeoven.TheAlbie-Coreinstructionscallforusingstandardfirebrickfortheflueson

eithersideofthecentralcore,providingsignificantmassforheatstorageinthisdesign.Theseheat-exchangechannelsareseparatedfromthecentralcorebyanexpansiongapfilledwithmineralwoolinsulation.Theinstructionsfurtherdelineateafullmineralwoolseparationofthefinishedinnerlifeandflueassemblyfromthefinaloutsideveneermaterials.

FIGURE8.56.Thisviewrevealstheslopingfirebox-floorpieces.Intheforegroundaretwotrapezoid-shapedelementsoftheAlbie-Corethatsupportthelarge,slopeddry-setthroatpiecesyettocome.PhotocourtesyofMaineWoodHeatCompany.

TheTemp-Cast

TheTemp-Castisnotablydifferentfromtheprecedingcorekit.Thoughit,too,producesaFinnishcontraflowdesign,thiscorepackageismadeentirelyofcastrefractoryconcretepieces.Nofirebricksarenecessary,andthecompanymarketsthiskitasonethatcanbebuiltbyanyone—eventhosewithnopreviousmasonryexperience.TheTemp-Castcoreconsistsofjustthirty-sevenlargeblocksofpreciselycastpiecesthatmatetooneanotherwithatongue-and-groovearrangement(seefigure8.57).Withagoodunderstandingoftheinstructions,evenafirst-timebuildercanassembletheentireinnerlifeinjustamatterofhours,notdays.

FIGURE8.57.AcutawayviewoftheTemp-Castheatershowsthelargetongue-and-grooveblocksofcastrefractorycomponentsinlightgray.IllustrationcourtesyofTemp-CastEnviroheat.

Thewaytheindividualpiecesarekeyedtooneanothercontrolsmovementofpiecesastheinnerlifeexpandsandcontractswithheatingandcooling.Thecompanyalsostatesthatthesekeysassurethatthereisnoleakageofexhaustgasesfromonepartofthesystemtoanother;such“shortcircuits”couldbe

unsafeorsimplymakeaninefficientunit.Theindividualtonguesandgroovesalsoservetomakeassemblynearlyfoolproof.TheTemp-Castbasicdesignproducesacompletedcorethatis22½inches

deep,36incheswide(includingcastflueelements),and77inchestall.Likeothercontraflowkits,thereareavailableadditionalfeaturessuchasasee-throughfirebox,acornermodel,andaversionwithabakeoven.AfinishedTemp-Castheaterisshowninfigure8.58.

FIGURE8.58.AcompletedTemp-Castmasonryheater.PhotocourtesyofTemp-CastEnviroheat.

TheCrossfire

TheCrossfireisanotherFinnishcontraflowdesignwithdifferentproportions.Thecompanytoutsitsmodelsashavingthelargestfireboxdoorintheindustry.LiketheTemp-Cast,theCrossfireisfactorymadeoflarge,interlockingblocks.This,thesimplestcoreoffered,hasjusttwenty-sixpiecesreadytobeassembledinjusthours—evenbyinexperiencedbuilders.Aneasy-to-followmanualandthefactthatthecorecanonlygotogetheronewaymakeinstallationalmostimpossibletomessup.Still,Iwouldrecommendanexperiencedmasonforanycoreproject.Onemistakeisliterallysetinstone.Likeallthekitsmentionedthusfar,theCrossfireisbuiltfirstandseparated

fromtheexteriorveneerwithanexpansiongapcreatedbywrappingtheentireinnerlifewithcardboardpriortofinishwork(asseenpreviouslyinfigure8.2).Thecardboardeventuallydisintegrates,leavingasmallairgaparoundthewholeheatercore.

FIGURE8.59.ACrossfiremasonryheaterjustaftercompletion.Noticehownarrowitis.Nootherstandardkitmakesaheaterthisnarrow.PhotocourtesyofCrossfireFireplaces.

Likemostcontraflowkits,theCrossfireoffersoptionssuchasabakeovenandsee-throughfirebox.Italsooffersthreedifferentsizesforheatingdifferentlivingspaces.Eachcorehasthesamefootprintdimensionsof16inchesby46inches.Thesmallestmodelisonly56inchestallwhilethemediumis76inchestallandthelarge,afull8feet.Byfar,amongmanufacturedcorekits,theCrossfireisthewidestandsimultaneouslytheshallowest.Theextrawidthiswhatmakestheverylargedoorpossible.Thecombinationofthewide,largedoorandtheoverallwideappearanceof

thefullyassembledandveneeredcoremakesthiskitheaterlookthemostlikeatraditionalAmericanopenfireplace,while,ofcourse,functioningasamasonryheater,withacompany-statedheatingefficiencyof78percent.

OtherCoresandSolutions

AlthoughFinnishcontraflowdesignsseemtodominatethemanufactured-corefieldinNorthAmericaasofthiswriting,thereareotheroptionsaswell.TheserangefromcorekitsdevelopedfromotherEuropeantraditionstocompletemanufacturedmasonryheaters,andevensomethatcomeveryclosetoduplicatingthecustom-designprocessoutlinedearlier.Thefollowingdoesnotpurporttobeacomprehensivelistofallpossiblemanufacturers’productsthatmaybeavailableintheUnitedStatesandCanada.However,itisrepresentativeofsomeofthegreatestvolumeofheaterssoldinNorthAmericaoutsidetheFinnishcontraflowkitsalreadyoutlined.Hereyouwillalsofindsomenewerinnovations.

TheBiofire

Ofallthekit-typeheaters,theBiofireistheonethatperhapsmostcloselyresemblesatrulycustom-designedmasonryheater.Ratherthanonesetmodularcoredesign,theBiofireisconstructedusingmodularpiecesthatcanberearrangedinaninfinitenumberofwaystoproduceverydifferentlysizedandshapedmasonryheaters.Figure8.60showsacutawayviewofaBiofiredesign,illustratingtheexhaustflow.AswiththeEnvirotechRadiantFireplace(laterinthissection)andtheTemp-Cast,thesemodularpieceshavetongue-and-groovejointstoassureproperalignmentandstructuralintegrity.

FIGURE8.60.AninternalviewrevealssomeoftheinnerlifeofastuccoBiofire.Thissameheaterin

operationisinfigure4.18.ImagecourtesyofBiofire,Inc.

Aswithatruecustomdesign,manyimportantfactorsaretakenintoconsiderationtoproduceaBiofire.Thecompanyaimstodesigneachnewheaterspecificallyforagivenhomeorlivingspace.Biofire’sengineersconsiderwhatkind,size,andheightthechimneyisorwillbefortheprojectbeforecreatingadesign.Biofirealsowantstoknowthegeographicelevationofthebuildingsite.Allthisinformationisusedtocalculatetheeventualspeedofthegasestravelingthroughthesystemaswellasflueandfireboxsizes.Toaugmentthisdesignprocessandtoaidthebuilder(whomustbespecially

trainedbythecompany),awoodenmodelismadeshowingtheentireconstructionandhoweachpiecewillbeassembledintotheunit.Aswithsomeoftheothercorekitsthathaveinterlockingpiecesthatcangointotheprojectonlyoneway,thewoodenmodelseekstoguaranteethateachpieceofaBiofirepuzzlewillbeinstalledcorrectlytoachievetheaimsofthecarefuldesignandengineering.Themodelissmall,asseeninfigure8.61,buteachflueisshownandeachpiecedefiningaflueisnumbered.

FIGURE8.61.Biofirecreatesawoodenmodelofeachprojecttonumberandshowtheplacementofeachpieceintheinnerlife.

FIGURE8.62.ABiofireinstuccowithjustafewtileaccents.PhotocourtesyofBiofire,Inc.

NoothermodularsysteminNorthAmericaconsiderschimneyheight,type,andsizeaswellashomeelevationinitsdesign.Asdiscussedearlierinthischapter,theseconsiderationsarecrucialtoformingthebestheaterpossible.Biofiremasonryheatersareprincipallyfinishedwitheitherstuccoorhigh-

qualityheatertilesfromAustria.Thecompanyoffersawidevarietyofcolorsandshapesofkachelnaswellasabroadselectionofsuperbdoors(seefigure8.62).Theexteriortiles,thecoremodulesthemselves,andthedoorsareimportedfromEuropewheretheselectionofmasonryheatermaterialsismuchmoredevelopedandcompletethaninNorthAmerica.

TheDouble-BellHeater

Thedouble-bellheaterdesignisbasednotontheuseofflues,ashasbeenoutlinedearlierinthischapter,butonwhatiscalledthesystemoffreegasmovement.Thegeneralideaofthesedesignsisthatgases,likewater,willfillanyvolume(“bell”orchamber)completelyandwillnaturallystratifybytemperature.Thehottestgaseswillnaturallypushtheirwaytothetopofthechamber.Thecoolestgaseswillnaturallybedisplacedtothelowestpartofthechamber.Itiscalled“freegasmovement”becausenoexternalforceisrequired

todrivethisstratification;thestratificationhappensfreelyinthepresenceofgravity.Chimneydraft,thedrivingforceinallothermasonryheaterdesigns,hasonly

onepurposeinthesystemoffreegasmovement:Chimneydraftpullsthecooledby-productsofcombustionoutofthesystem.Thefinalchimneyconnectionalwaysoccursinalocationlowinagivenvolumesothattheexhaustisalwayscoolerthanwhatremainsintheheater.Whileadraft-poweredsystemmovesallthegases,hottestandcoolestmixedtogether,throughthewholesystem,thedouble-bellsystemnaturallyassuresthatthecoolestgasesalwaysremainseparatefromthehottestgases.Onlythecoolestgasesatthebottomofanygivenbell(volumeorchamber)areabletomovetoanexitsuchasachimneyoranentranceintoanotherchamber.Becauseofthisseparation,andtheinherentfactthatonlythecoolestgasesmoveontothechimney,proponentsofthedouble-bellsystembelieveitissuperiorinoverallefficiencyandheatretention.Thenamedouble-bellstemsfromthefactthatmosttypicalresidential

installationsofthiskindofheaterhavetwochambersor“bells.”Inreality,aheaterbasedonthesystemoffreegasmovementcouldhaveanynumberofchambers.Thereareheaterswithonlyone“bell”andotherswithmany“bells.”Thenumberofchambersisdeterminedbytheplanoftheentireheaterconcept,ratherthananysetcoredesign.Thedrawinginfigure8.63showsthebasicconceptofthedouble-bellheater.

FIGURE8.63.Anuppercompartment(bell)andalowercompartmenteachcollecthotgases.Sincegasesnaturallystratifybytemperature,thecoolestgasesfalltothebottomandeventuallymoveontowardthechimney.ImagebyIgorKuznetsov.FIGURE8.64.Thisheater,builtusingthesystemoffreegasmovement,isagoodexampleoftheversatilityofthissystem.Thebenchesandalltheothershapesaredefinedbycontainersfornaturallystratifyinghotgases.DesignedandbuiltbyStovemaster;photocourtesyofAlexChernov.

Asyoucanimagine,giventhefactthatcombustiongaseswillfullyoccupyavolumeofanyshapeorsize,thesystemoffreegasmovementoffersunendingdesignpossibilities.Unusualshapesandlayoutsarepossiblewiththismethod.

Heatedbenches,compartments,ovens,stovetops,andmorearepotentialfeaturesandwillbeveryfunctional.Thenaturaltemperaturestratificationofhotterandcoolergaseswithinanyprovidedspaceassuresevenlyheatedsurfacesregardlessoftheconfiguration.Thesystemoffreegasmovementhasmostnotablybeenpopularizedin

RussiabyIgorKuznetsov,whoissaidtoberesponsibleforseveralthousandsuchheatersinhiscountry.Thedouble-bellconcepthasarrivedinNorthAmerica,thoughveryfewareproperlyeducatedondesigningsuchheaters.AlexChernovhasstudiedunderMr.Kuznetsovandhasyearsofexperiencebuildingheaterswiththismethodofdesign.Figure8.64isoneexampleofsuchaheater,andseveralothersarepicturedinthisbook,includingfigures1.1,3.9,3.10,5.8,6.19,and11.2.

EnvirotechRadiantFireplace

TheEnvirotechRadiantFireplaceisamodularcorekitcreatedmoreinlinewiththeGermanmasonryheatertradition.UnliketheFinnishcontraflow,whichjusthastwodowndraftchannelsoneithersideofthefirebox,theEnvirotechRadiantFireplacecorehasfiveupdraftandfourdowndraftfluesinitsbasicdesignasseeninthecutawayviewinfigure8.65.Itsmanufacturertoutsthisheateras“thecleanestburning(lowestemissions)ofanymasonryheateryettestedinNorthAmericabyanEPAcertifiedlaboratory”withtotalemissionsof0.8g/kgoffuelburned.ItmeetsstrictregulatoryrequirementsinthestatesofWashingtonandColorado—requirementsthatsomeothermasonryheatershavenotmet.

FIGURE8.65.AcutawayviewoftheEnvirotechRadiantFireplacerevealsitsintricateworkings.ImagecourtesyofEnvirotechMasonryHeaters.

TheEnvirotechRadiantFireplaceinnerlifeis,liketheTemp-Castoutlinedearlier,madeentirelyofcastrefractoryconcretecomponentsasseeninfigure8.66.Everypieceisnumbered/labeledforquickassemblyperthemanufacturer’sinstructions.Alltheseparateblocksarematedtooneanotherwithatongue-and-groovesystemthatassuresstructuralintegrityandproperassemblyandfit.Abuilderfamiliarwiththisproductcanassemblethismodularcorekitinlessthanoneday.

FIGURE8.66.AcompletedEnvirotechRadiantFireplacecorekit.Theentireinnerlifeiscastblocksofrefractoryconcrete.ProjectbyMasonryHeaterStore;photobyWendellShort.

TheEnvirotechRadiantFireplace“Classic”(seefigure8.67)isthestandard-sizedheaterand,whenfacedwitha4-inchveneerlikecommonbrick,resultsinaheaterthatis2feet,8inchesdeepand5feet,8incheslong.Itisalsoavailableinasmaller“Compact”versionthatisonly4feet,8incheslong.Aswithotherheaters,thissystemoffersasee-throughandbakeovenoptionaswell.Whenveneered,itmakesaheaterapproximately8feettall.Aswithothercorekits,theEnvirotechRadiantFireplacecorekitisassembled

first.Itisthenwrappedincorrugatedcardboard,aswasseeninfigure8.2,toformanexpansiongapbetweencoreandveneer.Theinnerlifeofthisdesignisthenenclosedbytheveneeroftheowner/builder’schoice.Asthisbookgoestopress,thecompanyisgettingreadytoofferpremadeveneersofeithercoloredconcreteorgranite.

FIGURE8.67.TheEnvirotechRadiantFireplace“Classic”veneeredinbrick.PhotobyWendellShort.

TheHelios

Debutingin2010isanewmodularmasonryheatercalledtheHelios.Theoriginatorandmanufacturer,NewEnglandHearthandSoapstone,introducedthistestedwood-burningapplianceasonethatcanberetrofittedintoanexistinghouse(orbuiltintoanewhouse)inamatterofafewdaysbytrainedtechnicians.Itisbuiltoneightlevelinglegstoaccommodateimperfectsiteconditionsoftenpresentinolderhomes.TheHelios’sintroductionatthe2010HPBAExpowonitafinalistplacingintheorganization’sannualVestaAwards.Theheateritselfismodern-lookingrectangularcubemeasuring40½inches

wide,35½inchesdeep,and73inchestall.TheHelioscomeswithmanyoutsideveneeroptionssupplied.Thestandardouterfinishisastuccofinish,appliedoverfireclayplatesandmesh.Asmentionedinchapter6,stuccooffersmanytextureandcoloroptions.Itisalsoavailablewithapremade,large-formatsoapstonefinishusingsoapstoneslabsmeasuring32by40inches.Anotheroptioniseightstandardcolorsoflarge-formatclay-basedtiles,withmorecolorsavailableasspecialorders.Yetanotheroptionbeingofferedisanewproductcalledbottlestone,arecycledceramicproductmadewith80percentrecycledglass

mixedwithclayandfired.Ofcourse,thesesurfacefinishescanalsobemixedandmatched.

FIGURE8.68.TheHeliosisthenewestmodularheateravailableinNorthAmerica.PhotocourtesyofNewEnglandHearthandSoapstone.

TheHelioswasdesignedtousethe“no-air-gap”methodofconstructionandwasdesignedwithcarefulcalculationoftheflues.Theheaterisconnectedtoanappropriatelysizedchimney,whichisdeterminedbyusingachartsuppliedwiththeproductthatrelatesavailablechimneyheighttothesite’sgeographicelevation.Inthisway,theHeliosmanufacturercombinesmanyofthecustomdesignfactorsdescribedinthistextinamodularheater.AcutawayviewoftheHeliosisinfigure8.69.

FIGURE8.69.AcutawayviewoftheHelios.ImagecourtesyofNewEnglandHearthandSoapstone.

Thismasonryheaterweighsalittleunder4,000poundswithmostoftheveneeroptionsandoutputsapproximately13,000BTUsperhour.LimitedemissionstestingsofaronitsperformanceshowsthelowestparticulateemissionsofanymasonryheateryettestedinNorthAmerica,at0.384g/kgoffuel.Themanufacturercreditsmuchofthecleanperformancetotheair-deliverymethodused.About50percentoftheairwashesthedouble-panedoorglass,andtheotherhalfisdeliveredthroughthefireboxwalls.(Youcanseeasimilarfireboxwithairsupplyinfigure11.6.)

TulikiviSoapstoneFireplacesandBakeovens

TheFinnishcompanyTulikiviisresponsibleforasignificantpercentageofallmasonryheaterssoldinthe

FIGURE8.70.Tulikiviisknowntoproducehigh-quality,uniformlyfinishedsoapstonemasonryheaters.Thisstovehassomeincredibledetailslikethecarvedlizards,acustombrass-and-irondoor,andataperedupperbodyabovethedeeplyshapedmantel.Noticehowthestonessurroundingthedoorarelikeradiansofthecircle.PhotocourtesyofTulikiviCorporation.

FIGURE8.71.Ceramic-linedTulikivifireboxeswillburnhotterandcleanerthantheall-soapstoneversion.PhotocourtesyofTulikiviCorporation.

NorthAmericanmarkettoday.Tulikivicreatesmasonryheatersthatareentirelysoapstoneinsideandout.Thefireboxandinnerlifearemadeofsoapstone,creatinganimmensemassofheat-storagecapability.Asyoumaysurmise,thisFinnishcompanymainlyproducesacontraflowmasonryheater,withfewexceptions.SomealtertheFinnishdowndraftdesignbyincorporatingoneormore“up”fluessothatachimneycanconnecttothetopoftheheater.TheTulikiviCorporationmanufacturesaveryfinelyproduced,expertly

craftedproductwithextremelytighttolerancesonthefitofallstonecomponents.Doorsandotherhardwareareveryhighquality,asistheuniformityofstonefinish.Thesoapstoneisalwayshighqualityandsuperblyanduniformlyfinished.Inrecentyears,Tulikivihasdevelopedimprovedair-supplyandfirebox

designs,calledthe“whirlbox,”forhotterandmorecompletecombustion.Byliningtheotherwise-soapstonefireboxwithaceramicliner,asseeninfigure8.71,whichalsoservesaspartoftheair-deliverysystem,combustiontemperaturesarehigherthanthemoreclassicdesignwiththeall-soapstonefirebox.Aswesawinchapter6,soapstonetransfersheatquicklycomparedwithothermasonryand,whenusedinafirebox,caneventransfertoomuchheatfromthefire,loweringcombustiontemperatures.Changingtothenewerfireboxdesignnotonlyimprovesperformancebutalsointroducesaneasilyreplaceablesysteminthepartoftheheaterthatgetsthemoststress—thefirebox.Whilethecustom-designprocessoutlinedearlierproducesaheaterfora

specifichomeorlivingspace,TulikiviCorporationproducesliterallydozensofstandardmodels,suggestsminimumfluerequirements,andpromotestheirheatersforheatingspecificsizerangesofspaces.Theirslantistooffermany

optionsforagivenspaceinaready-to-deliverand-installpackage.ThemanufacturingfacilityinFinlandcutsallthepiecessothatbuildersinNorthAmericaneedonlyunpackthecratesandbeginbuilding.MostTulikiviheaterscanbebuiltonsiteinjustafewdays.Inasense,Tulikivimodelsareaboutascloseasyoucangettoamasonryheaterequivalentofametalwoodstove:Itistakentoahome,builtbyfactory-authorizedtechnicians,hasachimneyattached,andisreadytouse.Tulikividoesalsooffercompletecustomheaterdesigns,butusuallythebesteconomyisaccomplishedbymodifyingexistingstandardmodels.

TheInnerLifeLivesOnAmasonryheatercanbealmostanythingtheownerwouldlike.Theinnerlifeiswhatmakesitallfunctionandproduceitswonderfulheat.Itmustbecarefullydesignedtoachievethebestresults,maximumefficiency,andcleanlinessofburn.Everythingfromtheelevationofthebuildingsitetothesizeandheightofthechimneyinfluencehowtheheaterwillperformandhowthecoreshouldbedesigned.Thefireboxsizemustrelatetotheamountofheatyouwanttoproduce(quantityoffuel);thatonefactwillinfluenceallotheraspectsoftheheater.Forthosewithouttheskillstoproperlydesignaheater,numerouscorekitsare

availableintheNorthAmericanmarket.Thesemanufacturedheatercorestakethehead-scratchingoutofbuildingamasonryheaterandoffersimpleconstruction,predictableresults,reasonableprices,and,invariably,happycustomers.Thoughmostkitsoffersomewhatlimitedshapeoptions,thefactthatamasonryheatercanbeveneeredwithanymasonrymaterialmeansthereisamasonryheatersolutioninNorthAmericaforeveryone.Withouttheinnerlife,amasonryheaterhasnolifeatall.Whenfedgoodfuel,

amasonryheaterpuffsoutitschestand,likeahardworkinglaborer,producesvolumesofheat.Asitcools,itrelaxesandexhales,shrinkingbacktoitsoriginalsize.Goodcoredesignletstheheaterbreathelikethisfordecades:Working,relaxing,working,relaxing.Theheaterisalivingbeingintheheartofthehouse,providingrealwarmthtothehumanbeingsfortunateenoughtoliveandbreathewithit.

FIGURE9.1.ATulikiviboulderheateristhefocalpointinthecenterofthishome.Notethebroadraisedhearthwithnatural,free-formedge.Thebacksideofthisheaterisshowninfigure11.11.PhotocourtesyofWarmStoneFireplacesandDesigns.

CHAPTERNINE

Codes,Clearances,Footers,andFoundations

FewpeoplehaveheardoftheTowerofSuurhusen.ItwasbuiltintheMiddleAgesinSuurhusen,EastFrisia,Germany,asanadditiontothetownchurch.Thetowerstandsnearly90feettall.Accordingtothechurch’sWebsite,1thechurchhasservedmanyimportantfunctionsoveritsmulticenturyexistence,including(ofcourse)itsreligiousfunctions,asasafehavenduringwarsandseverestorms,andevenasaLatinschoolrunbyDutchmeninthesixteenthcentury.Likemanyoldbuildings,ithashaditsshareofrepairsoverthemanyyears.Noone,however,hasattemptedtocorrecttheleanthatputsthistoweroffcenter,atthetop,bynearly8feet.ItholdstheGuinnessworldrecordasthemosttiltedtowerintheworld.Itleansatanangleofmorethan5degrees,thusexceedingtheleanofthemorefamousTowerofPisabymorethanadegree.Apparently,thechurchandaccompanyingtowerwerebuiltonmarshy

ground.Themassivemasonrystructuresabovegroundwerelaidonafoundationofoakplanks.Thepresumedstoryisthattheoakplanksweresufficientwhilethegroundremainedwetandthewoodremainedsoaked.Then,whenthegroundwasdrainedinthenineteenthcentury,thewetwoodsimplyrottedandthetowerbegansinkingintothesoftmushbelow.Theleaningofthetowerwasfirstnoticedanddocumentedin1885.Sincethen,remedialactionhasbeentakentopreventitstotalcollapse,andthebuildinghasbeenusedasrecentlyasthemid-1980s.Themoralofthestoryseemstobe,“Donotsupportyourmassivemasonry

structureonoakplanksinmarshyground,thensubsequentlydraintheland.”Okay,maybethat’salittlefacetious,butitiscertainlythecasethataheavymasonrystructurelikeamasonryheater,whichcouldeasilyweighseveraltons,needsadependablefoundationthatcanbeexpectedtolastaslongastheheateritself.Theleaningtowerexamplealsointroducestheroleofcodes.BuildingcodesthroughoutNorthAmericahaveastheirprimarypurposetoaidinbuildingsafestructures—onesthatarenotgoingtoleanorotherwisebecomeapotentialhazard.Codeandclearanceissueswillbeaddressedinthelatterpartofthis

chapter.Masonryconstruction,byitself,isthemostdurablewaytobuildastructure,

since,unlikewood,itisnotreadilybiodegradable.Whenmasonryisprotectedcompletelyfromweatherand,particularly,water,ithasanear-endlesslongevity.Amasonryheaterisdestinedforaverylonglife.It’swisetosupportitwithcomplementarytechniques.

SupportYourLocalMasonryHeaterThereareafewbasicchoicesastothetypeoffoundationorsupportstructuretoputunderamasonryheater.Allofthemwork,havebeenused,andwilllastifdesignedproperly.Whatisbestinagivenprojectgenerallydependsonthezoningoftheareaandtheexacttypeofheatertobeinstalled.Itispossibletosupportsomemasonryheaterswithwoodframing,withsteelframing,orwithmasonryconstruction.Allhavecertainadvantagesanddisadvantages,dependingonthesituation.Onewayortheother,allsupportmethods(foundations)ultimatelytransfertheweightofthemasonryheatertotheearthitself,spreadingtheloadoveralargeareaviafooters.

Footers

Afooter,asthenamesuggests,istheactualthingthatcontactstheearth.Likehumanfeet,afooter’spurposeistoprovideadequatestabilityandtoabsorbandspreadtheweightofeverythingontopofitoverthegroundsuchthattheleaningtowerdescribedpreviouslycannothappen.Usually,inmodernconstruction,thefootersofbuildingsoranyotherpermanentstructurearemadeofreinforcedconcrete—concretewithreinforcingfibersorsteelrodsembeddedpermanentlyinthemix.Theprincipalideaoffootersistohaveenoughsurfaceareacontactingthegroundinproportiontotheamountoftotalweightbeingbornethatthestructurewillalwaysbestableandnotsinkintotheground—ever.Inthecaseofhumanbeings,theweightandpressures(fromwalking,running,

orjumping)canbeseveralthousandpoundspersquareinch(psi).Ifallthatpressurewasterminatedintheanklebones,ajointhavingacross-sectionalareaofperhaps6or7squareinches,apersonwouldsinkintoevensomeveryhardground.Agrownman,however,mayhaveafootthatistrulyclosetoafootlong

andaveraging3to4inchesinwidth.Thismeansthepressuresarespreadoveranareaofabout36squareinches—fivetimestheareaoftheankleitself.Inthisway,3,000poundsofpressure,createdfromagrownmanjumping,isdispersedwithanaveragepressureofjustover80poundspersquareinch.Sincemostsoilscanreadilysupportsuchweightwithoutsubstantiallydeforming,themancanjumpupanddownonthegroundandleavelittleornofootprint.Ofcourse,mostofusareawarethatthesamepressureappliedonloose,sandysoilwouldhaveadifferent,highlyvisibleresult.Suchisthecasewiththestructuralfootersofhomesandmasonryheaters.The

footermustbedesignedtospreadoutthatweightsothatthewholeassembly—footer,foundation,andmasonryheater—willneverbeunstable.ThroughouttheNorthAmericancontinent,soiltypesvaryconsiderably.Eveninonelocality,differencescanbesubstantial.InmyareaofOhio,soilthatresemblesbeachsand(whichitapparentlyoncewasthousandsofyearsago)isfoundjust20milesfromhardclaysoiland20milesinanotherdirectionfromveryloamysoil.Everysoiltypehasadifferentcapacitytoabsorbweight.Afooterdesignedforoneareamaynotbegoodenoughforanother.Forthisreason,localbuildingcodes,codeofficials,or,morereliably,astructuralengineerorarchitectshouldbeconsultedifthereisanydoubtastohowtodesignafooterforaspecificsoilcondition.NowthatI’vedispensedwithsuchwarningsandalarms,youshouldbeaware

that,forthemostpart,masonryheaters,thoughverydense,stillexertrelativelysmallamountsofpressure.Forexample,a7-foot-tallheater—withrelativelynarrowdimensionsof4feetby3feet—hasatotalfootprintof12squarefeet.Twelvesquarefeetis1,728squareinches.Iftheheaterismadewithalotofverydensematerials,likesoapstone,forexample,itcouldweighcloseto8,000pounds.Ifitweresittingonafooterexactlythesizeofitsfootprint,12squarefeet,itwouldexertapressureofabout4pounds,10ouncespersquareinch.Mostofuscanvisualizethatmostsoilsonwhichahomemightbebuiltwillreadilyhandle5psiwithoutdeformingorfailing—withoutallowingthemasonryheatertobecomealeaningtowerofheat.Thisisasimplification,forsure,sincenoconsiderationwasgivento,perhaps,

atallmasonrychimneyaswellasthefoundationitselfonwhichtheheatermaysit.Alloftheseaddweightandpressure.Itshouldbeclear,though,thattheoverallpressuresarenotimmense.Andamasonryheaterthathasalargerfootprintwillhaveevensmallertotalpressure.Toputthisinperspective,considera250-poundmanstandingononefoot.Ifhisfoothasanareaof35

squareinches,asproposedabove,heexertsabout7psi—morepsithanour4-by-3-by-7masonryheater—ontheearth!Thoughlocalbuildingofficialscanoverruleawrittenguideline,ingeneral,

footerthicknessis12inches.Ofcourse,itshouldalwaysbebelowfrostlevelandpouredonundisturbedormechanicallycompactedsoil.Inaddition,thefooterusuallyisspecifiedtobelargerthanwhatevermassmayberestingonit;oftenthefootermustbelargerbyatleast6inches,oneveryside,thanthefoundation.Themixofconcretefromwhichafooterispouredisalsosometimesdictatedbycodeorspecifiedbyanengineerorarchitect.Frequently,a3,000psimixisused.Inaddition,reinforcementshouldbeaddedtotheformwork.Reinforcingsteelbars(rebar)orreinforcingfibersinthemixservetopreventconcretefromfailing.Itissaidthattheonecertainthingaboutconcreteisthatitwillcrack.Reinforcementassuresthateveniftheconcretedoescrack,itwillnotcomeapartthankstothemechanicalconnectionscreatedbythereinforcement.Additionalrequirementsmaybenecessaryinareasconsideredseismiczones.Thereisnosubstituteherefordoingresearchonlocalrequirementsandmethods;thisisthetruebasisofanheirloom,many-lifetimeappliance.

FoundationsWhilethefooterislikethehumanfoot,ultimatelyabsorbingalltheshocksorweightfromeverythingaboveit,thefoundationorsupportstructureunderamasonryheaterislikethehumanlegs.Thefoundation,thelegsoftheconstruction,carriestheloadofthemasonryheateraboveandtransfersitdowntothefooter.

Itis,ofcourse,possibletohavenofoundationatallandjustafooter.Suchwouldbethecasewithahousethathasapouredconcreteslabandnocrawlspaceorbasement.Herethemiddlemanhasbeencutoutoftheequationbecausetheloadoftheheaterrestsdirectlyonthefooter,oftenpouredcontiguouslywiththeslabitself.Mosthomes,however,haveeitheracrawlspaceorabasementbelowthe

mainlivingareas.Sincethemainlivingareaisalmostalwaystheprimeplaceforamasonryheater,itwillneedafoundation.

MasonryFoundations

Thereisnoequaltothestrength,permanence,andeconomyofasimplemasonryfoundationunderamasonryheater.Thispointcannotberepeatedenough:Everymasonryheaterisaunique,potentiallyheirloominstallationthatwilloutlivetheoriginalownersandtheirchildrenalike.Themasonryfoundationcompletesapackageofnearlyindestructiblequalityandendurance.Amasonryfoundationcannotburn,willnotdeterioratefromweathersinceitiswithinthehome,willnotbeeatenbybugs,farexceedsstrengthrequirementsforamasonryheater,andrarelyrequiressubstantialengineering—astheotheroptionsmay—toassureproperloadtolerance.Itspermanencematchesthatofthemasonryheater.Theyaremeantforeachother.Masonry,inthiscase,referstoeitherpouredconcreteoraconcreteblock

structureunderneaththemasonryheater.Obviously,brickandstonecouldalsobeused,butrarelyareforthisutilitarianpurposebecausetheyaddunnecessaryexpense,unlessthebasementdecorwillrequiresuchalookanyway.Masonrymaterialsareextremelyinexpensiveforthisapplication,especiallywhenfactoredovertheexpectedlifetimeoftheappliance.Goodmasonscanbuildatypicalsupportforamasonryheaterinveryshortorder.Inbrief,theonlytwodownsidesIcanthinktoattributetomasonryfoundationsisthattheytakeupspaceandarenotpretty.Eventhespaceissue,however,canbeaddressedincreativeways,asshallbeseen.Oneofthebestfeaturesoftheall-masonryfoundationstructureisthatit

entirelyliberatesthewholemasonryheaterconstructionfromthewood-framedstructureofthehouse.InzonedareaswithstrictadherencetobuildingandfirecodessuchasthoseoftheInternationalResidentialCodeandtheNationalFireProtectionAssociation,therewillbenootheracceptablesupportstructureforawood-burningmasonryheater.Everyaspectofsuchaninstallationhastobeseparatedbyuninsulatedairspacesthatguaranteenoheatcanaccumulateandtransfertowoodenframingmembersofthehouse.Thisassuresthatthewood-burningheatercanneverbethecauseofafireinahouse,exceptbyutternegligenceoftheuser.Builderswilloftenlookatamasonryheaterfoundationasanothersupport

theycanuse.Tothem,itmayseemaconvenientstructureonwhichtorestamajorwoodenbeamorpartofthefloorsystem.Strictlyfollowedfirecodewillnotallowthisuse;itshouldonlybedonewiththeblessingsofthelocalcodeofficialoranarchitect.

MasonryFoundationAnatomy

Itiseasytopicturethefoundationandfooterofaconstructionasalegandfootsupportingeverythingabove.Amoreaccuratecomparison,however,isseenbylookingatthewayatypicalhouseisbuilt,becauseamasonryheateranditsfoundationareamicrocosmofthatmoreextensiveconstruction.Thehouseitselfhasitsownfooter.Onthatfooterrestsafoundationwall.Onthatfoundationwallrestsawood-framedplatform.Finally,onthatplatform—thefirst-floordeckasitiscalled—therestofthehouseisconstructed,includingexteriorwalls,interiorwalls,additionalfloorlevels,andtheroof.

FIGURE9.2(left).Concreteispouredintotheformedcavityforafoundationcappingslab.Noticesteelrebartiedtogetheron6-inchcenters.Theprotrudinginsulation-wrappedwoodintheforegroundistoformapassagewaythroughthepouredslabfordumpingashintothefoundationcavitybelow.|FIGURE9.3(right).Theconcretepouriscomplete.PhotosbyJulieCline.

Themasonryheaterassemblyisconstructedinthesameway.Afooterispouredandfoundationwallsconstructeduponit.Atthetopofthefoundationacappingslab—literallyaslabthatcapsthetopofthefoundation—ispoured.Thecappingslabisthe“deck”onwhichtherestofthemasonryheaterisbuilt.Usually,thecappingslabislargerthanthefoundationstructureitselfandcantileversoveritsedgesononeormoresides.Oftenthisisforpurposesofextendedhearthsoradditionalsittingbenches.However,aslabalsomaybecantileveredpurposelytominimizehowmuchspaceistakenupinthebasementbythefoundation.Forexample,iftheheateritselfistobe6feetlongbuta6-foot-longfoundationinthebasementwouldimpedemechanicalsystemsorotheruseofthespace,a4-foot-6-inch-longfoundationmaybebuiltwiththecappingslabcantileveredtheextra18inches(seefigure9.4).Sometimesthefirstthingonthe“deck”createdbythecappingslabisa

structuralinsulatedbasethatpreventsheatfromthemasonryheaterwickingintothefoundationstructureand,byconduction,totheearth.Anumberofmaterialscanbeusedforthispurpose,includingSkamolex,Foamglas,andinsulated

firebricks.Notethatsometimesthisinsulationlayerisomittedbecauseotherprovisionsaretakentopreventlossofheatintotheslab.Forexample,aheatermightbebuiltonlegs;oritmayhavebeendesignedtohaveinsulationinternallydothesamejob.

FIGURE9.4.Acantileveredslabcanbridgeoverobstructionsbeloworsimplycanbemadetosupportanextendedhearth.Eitherway,itreducesthetotalfootprintsizeofthefoundation.

Ontopofthestructuralinsulationisoftenacementboardproductorsimplyabasecourseor“subfloor”ofbricks.This“subfloor”isoftenatthesamelevelorjustslightlybelowthewoodensubfloorofthehome,thoughattimesitwillbehigher.Fromthatpointbeginstheactualconstructionofthemasonryheater.

AUtilitarianFoundation

Asdescribed,themasonryheaterfoundationisverymuchafoundationwithinthefoundationofthehouse.Justasthefoundationofahousemaycreateausablespacecommonlycalledabasement,thefoundationofamasonryheaterlikewisecreatesapotentiallyusablespace.Howthatspaceisuseddependsonthedesiresofthehomeownerand,possibly,onthedesignofthemasonryheater.

FIGURE9.5.Foamglas,thecharcoal-coloredmaterial,waslaidonthefoundationcappingslab.CementboardwasthenbondedtotheFoamglas.PhotobyJulieCline.

AshCollectionOneverycommonuseofthislittlefoundationcavityisforashcollection.Evenoldtraditionalfireplaceswereoftenfittedwithanashdoorinthefloorofthefireboxthatallowedthehomeownertosweepashesdownintothefoundationcavity.Thiscansometimesbedonewithamasonryheateraswell,dependingonitsdesign.Inthebasement,thefoundationitselfmusthaveacleanoutdoorsothat,ultimately,ashescanberemovedatthebasementlevel.Thishelpspreventthespillageofashesinthemainlivingarea.Amasonryheaterfoundationmayhaveenoughspaceforseveralseasonsofashcollection(thoughmostownerscleanouttheashatleastannually).

FIGURE9.6.Anashdumpfromthefireboxdeliversashtothefoundationcavity.An8-by-8-inchcleanoutdoorinthefoundationallowsaccessforashremovalinthebasement.PhotobyJulieCline.

AshCollectionPlus!Basementssometimeshaveadoortotheoutside.The“walk-out”basementisparticularlypopularwithhomesbuiltonhillsides.Well,thefoundationforthemasonryheatercanbea“walk-in”foundation.Ifthemasonryheatercomplexthatitissupportingislargeenough,itmaybefeasible

toinstalladooropeningintothiscavityanduseitforstorageorsomeotherpurpose.Itisstillpossibletomountametalashcollectionboxorcanistertothe“ceiling”ofthislittleroom,sothatyoucanenjoytheconvenienceofasmallclosetinthebasementwhilestillbeingabletoremoveashesthere.

TheWalk-ThroughandMoreThoughthebasementofahouseusuallyhasasmany(exterior)wallsasthehouseitself,amasonryheaterfoundationdoesn’tnecessarilyhavetobeanenclosedfoundation.Whatisnecessaryisthatthefoundationprovideadequatesupportforthecappingslabandthemasonryheateritself.SometimesthiscanbeachievedwithaU-shapedfoundation,twoparallelfoundationwalls,ormaybeonefoundationwallandacoupleofcolumns(seefigures9.7–9.9).Theseideascancomeinparticularlyhandydependingonthesituation.For

example,somepeoplefinishabasementtobeacompletelyself-sufficientapartment.Perhapsinthemiddleofthisapartmentisahallway.Butwait,inthemiddleofthemainfloorofthehouseissupposedtobeamasonryheater!Solution?Awalk-throughfoundationcanbecomeapartofthathallwayatthesametimeitfulfillsitsstructuralfunction.AU-shapedfoundationcouldbetransformedintoanentertainmentcenterfor

afinishedbasementrecreationarea,areflectivewallforadownstairsconventionalmetalstoveinaninfrequentlyusedworkshop,orasawood-storagecontainerperhapsrightnexttoawoodwaiter(describedinchapter6).Itcanalsosimplybeaspacedivider.Anytimetheplanistoactuallyusethebasement,whetheritisasaworkarea,playorlivingarea,orsomecombination,itisusuallypossibletocomeupwithideasastohowtomakethemasonryheaterfoundationanassetandnotjustaspaceoccupier.Inallcases,alternativefoundationdesignsshouldbereviewedbyastructural

engineertobecertaintheywillwithstandtheweightofthemassaboveandthetestoftime.Everyheaterandsituationisdifferentandmaycallfordifferentconcretethicknesses,differentamountsofsteelreinforcement,andsoon.It’sworthhavingaprofessionalreviewthedetails.

FIGURE9.7.(left)Amasonryheatersitsonacappingslabbridgingtwoparallelfoundationwalls,makingawalk-throughfoundation.|FIGURE9.8.(center)AheateronaslabbridgingaU-shapedfoundationstructure.Thecavitycreatedcanbeusedforstorage,shelves,anentertainmentcenter,orthelikeinthebasement.|FIGURE9.9.(right)Amasonryheateronaslabsupportedbyonefoundationwallandtwoconcrete-filledsteelcolumns.

Amasonryfoundationcanbebuiltinavarietyofwaysandyetprovidesultimatestrengthandlongevity—likethemasonryheateritself.Innewconstruction,itiseasilythebestchoiceforsupportingamasonryheater.Yetmasonryheatersofmanyshapes,sizes,andweightshavebeenconstructedonalternativesupportstructuresorfoundationsandprobablywillbeinthefuture.Wood-andsteel-framedstructuresareheretostay,soitisworthlookingathowtheyaredoneaswell.Wood-FramedFoundation

Mostmasonswillcringeatthethoughtofsupportingamasonrystructurelikeamasonryheateronsometypeofwoodframing.Itcertainlycanbearguedthatwooddoesnothavetheguaranteedlifeexpectancythatthemasonryhas,sowhywouldyouwanttojeopardizetheonefortheother?Forexample,ahousefirenormallywouldnotnecessarilydestroyamasonryheater,butitcertainlycoulddestroyawoodenfoundationandthustoppleamasonryheater.Woodisalsosubjecttorotanddecayifnottreated.Theflipsideofthisargument,however,isthat,again,themasonryheateris

entirelyinsidetheprotectiveconfinesofthehome.Thesupportstructurewillnotbeexposedtoweatherelementssuchaswaterthatwillrotit.Andwhilewoodiscombustible,itisworthaskingthequestion,“Ifthehouseburnstotheground,ofwhatvalueisthemasonryheateranyway?”Inotherwords,assumingthehouseismaintainedingoodconditionandused

asdesigned,itislikelythatawoodsupportstructureorfoundationforamasonryheaterisfeasibleandcanendure.Ingeneral,thereareacoupleofwaysinwhichwoodframingmightbeusedtosupportamasonryheater.Thefirstistosimplyusethewoodframingthatotherwisesupportsthemainlivinglevelfloorandmodifyittosupportthemasonryheater.Thismethodwouldlikelybechoseninordertoavoidtakingupspacedirectlyunderthemasonryheaterwithafoundation.Theothermethodwouldbetobuildastructuredirectlyunderthemasonryheateritself,throughthebasementorcrawlspace,toafooterbelow.

LOCALREQUIREMENTS

SomejurisdictionsandbuildingdepartmentsstrictlyfollowInternationalResidentialCodeandnationalfiresafetycodesandregulations,whichspecificallyrequireanymasonrysolid-fuel-burningappliancetobebuiltonlyonamasonryfoundation.Consultlocalauthoritiesbeforeconsideringalternatives.Ideassuggestedhereshouldbethoroughlyreviewedbythearchitectorengineeronthejoband/orallapplicablebuilding-codeofficials.Theappearanceofthesenonmasonrysolutionsinthisbookinnowayconstitutesarecommendationfortheiruseinanyparticularproject.SomeUnderwriter’sLaboratories(UL)listedmanufacturedbrandsofmasonryheatershavebeentestedandapprovedtobebuiltoncombustiblefloorstructures.Thosemasonryheaterswithoutsimilarcredentialsmayhavetobesupportedonamasonryfoundation.

UsingCommonFloorFraming

Mostwood-framedfloorsinhousesarenotengineeredtosupportaheavyitemwithasmallfootprintlikeamasonryheater.Sure,theymaysupportagrandpiano,butthatisstilllessthanaton,whilemasonryheatersgenerallyareatonormore.Thetruthis,acommonwood-framedfloorsystemmightsupportatonofweight.Whatitwilldo,however,isshowalotofdeflection.Inotherwords,amasonryheaterwouldbendthefloor-framingmembers—showingthatitismassivelystressingthewood.(Considerthataconventionalwood-framedfloorisdesignedtocarryloadsofabout65poundspersquarefoot.Asmallmasonryheaterthatweighs2,000poundsandcovers6squarefeetoffloorexerts333poundspersquarefoot.Thereisnoreconciliationhere,onlytheoptiontoredesign.)Undertheseconditions,thefloorwouldbebouncyandnotallthatfar

fromphysicalfailure.Anormallyframedfloorneedsmodificationtoitsdesignandconstructionifitistosupportsuchunusualweights.Sinceeveryhomedesignisdifferentandeveryfloorspanisdifferent,itis

impracticalinthistexttoattemptdetailedanalysisofeverypossiblesituation.Sufficeittosaythatarelativelyconventionalwoodenfloorsystemwillhavetoincorporateeithermorefloorjoists(spacedclosertogetherthannormal),largerframingmembers(intheverticaldimension;forexample,2by12sinsteadof2by10s),orsomecombinationofthese.Inaddition,today’sbuilderandarchitecthasadditionalspecialwoodproductsavailablesuchaslaminatedwoodbeams,truss-shapedjoists,andsoonthatcanbeusedforspecialloadingsituationslikethis.Thebestadviceistohaveanengineerorarchitectproperlydesignforsuchaspecialcircumstance.

UsingaWoodenSubstructure

Whilethefirstoptiondependsondesigningwood-framingmembersthatarerunninghorizontally(floorjoists)tosupportaheavyload,theideaofawoodenstructuredirectlyunderthemasonryheatermassdoesnot.Instead,itmakesuseofwood’sconsiderablecompressivestrength.Woodstandingonend,asintheverticalwoodframingmembersintypicalhouseconstruction,isverysuitabletocarryingheavyloads.Evensoftwoodslikepinecantakemorethan5,000poundspersquareinchofpressurewithoutcrushing.Thisispreciselywhytheconventionallyframedhouseworkssowell:tremendousfloorloadsareevenlydistributedovernumerousverticalstudsthattransferalltheloadstothefoundationandfooterbelow.Thesimplestapplicationofthisprincipleisachievedbymimickingthewall

structureofthehouse.Oncethefootprintsizeofthemasonryheaterisknown,aplancanbedrawnfora“room”madeofstudwallsthesizeoftheheater.Forcompactheaters,thismightbemorelikeacloset.Forlargecomplexes,itcouldindeedbeasmallroom.This“room”couldbebuiltunderthefloorjoistsofthemainfloor,whichhavebeen,perhaps,doubledortripledasperanengineer’sinstructions(seefigure9.10).Alternatively,thelittleroomwallscanbeusedtosupportaconcreteslabonwhichtheheaterwillbebuilt.Ifso,thewoodmembersshouldbeseparatedfromtheslabwithamoisturebarrier.Eitherway,thisarrangementprovidesanenclosedspaceinthebasementlevelthatcanhaveadoorwayandbecomeusefulasstorage,anentertainmentcenter,orachildren’shideout.

FIGURE9.10.Apossiblesupport-structurescenarioutilizingstudwallsanddoubledjoistsonnarrowcenters.

Amoreopenconfigurationofwoodensupportwouldmakeuseofheavytimbercolumnsandbeamsperformingthesamefunctionasthestudwallsdescribedabove(seefigure9.11).Inthiscase,thewoodframingmaybepermanentlyexposed.Thoughitobviouslyoccupiesspaceinthebasement,thefactthatyoucanseepastalltheframingmembersmeansitleavesanappearanceofopennessthatcannotbeachievedbybuildingasmallroomthere.Thisisalsoamorelikelyandsimpleoptionforacrawlspacewhereitisobviousthereisnovaluetoasmall“room.”Asalways,checkwithanarchitectorengineertoascertaintheappropriatedimensionforthetimbersusedinthissolution.Animportantnoteforanysituationinwhichamasonryheaterwillbebuilton

awoodflooristhatappropriatemethodsneedtobeusedtoseparatethemasonryheater,whichmaygetquitewarmnearfloorlevel,andthewoodenfloor.Astructuralinsulationmaterial—onethatwillnotcompressundertheweightoftheheater—mustbeused.Dependingonthedesignoftheheateritself,youmayneedtotakeadditionalprecautionstoguaranteethatthereisnofirehazardfromhotmasonrynearwoodstructures.Formoreonclearancetocombustiblematerials,seethatsectionlaterinthischapter.

FIGURE9.11.Amasonryheaterwithheavytimbersupportsunderdoubledfloorjoists.Theheaterrestsonathicksteelplate,cementboard,andstructuralinsulation.Thestructuralinsulationprotectsthewoodenfloorfromheat.

SteelFraming

Likeitsnaturalequivalent,wood,steel-framingsolutionscomeintwogeneralconfigurations.Eitherhorizontalbeamsareusedtocarrytheloadofthemasonryheater,oraverticalsteelsubstructureisbuiltunderit.Thereareacoupleofadvantagestousingsteelratherthanwood.First,steelisfireproof,rot-proof,andnotatargetofanyinsects.Inthisway,steelframingismoreforgivingofunexpectedoccurrencesinthelifespanofahome.Shouldthebasementorcrawlspaceturnouttobedamperthanexpected,forexample,youneedn’tfearthatthesteelwillrot,whileuntreatedwoodmight.Iftherehappenedtobeafirelocalizedneartheheater,thesubstructureoftheheaterislikelysafe.Also,steelbeamsandcolumnsarevastlystrongerthanwoodencounterpartsofthesamesize.Inthecaseofalongfreespanandaheavyload,woodenbeamsmayneedtobequitelarge,particularlyintheverticaldimension,comparedwithsteelbeams.

FIGURE9.12(top).Thehome’scentralI-beamsupportstwoadditionalsteelbeamsthatcarrytheloadoftheheater.Insteadofthedoubledwoodenfloorjoistsshown,thesteelbeamscouldbespannedbyreinforcedconcrete.|FIGURE9.13(bottom).Parallelsteelbeamsjoinedtothehome’scentralI-beam.Doubledjoistsrestonthebeams;somewoodenmembersnotshownforsakeofclarity.

FIGURE9.14.Concrete-filledsteelcolumnssupportasteelpaninwhichaconcretepadispoured.Theheaterisbuiltonthatreinforcedpad.Notice12-inch-thick(orthicker,perengineering)concretefooterundereverything,includingthebasementfloor.

UsingSteelBeams

Manyhomesbuilttodayarealreadydesignedwithoneormoresteelbeams,oftensupportedbysteelposts,runningthelengthofthehouseandsupportingthewoodenfloorjoistsabove.Aparallelbeamalongsideoracoupleofperpendicularsteelbeamsattachedtothatcentralonecouldcreateaframeworkonwhichtopouraconcreteslabthatwouldthenholdthemasonryheater.Likewise,acoupleofparallelbeamscansupportdoubledortripledwoodenfloorjoistsintheareaoftheheater,providingenoughsupportfortheheavyweight(seefigures9.12and9.13).

UsingaSteelSubstructure

Likeitswoodencounterpart,asteelfoundationcouldbemadewithsteelstudsandfinishedtobearoom,oritcouldbesimplerassembliesofbeamsandsteelposts.Onceagain,thisstructurecansupportaslabonwhichthemasonryheaterrests,oritcandirectlysupportthewoodenframingofthefloor,asshowninfigure9.14.

BuildingCodesandClearancetoCombustibleFraming

Safetyistheprincipalconcernofbuildingcodes.Somebuildersandhomeownersdislikeoraresuspiciousofthebureaucracyinherentinbuilding-coderegulationsandenforcement.Nevertheless,theintentistoprovidegreaterassurancethatstructuresthatarebuiltwillbesafefortheinhabitantsbothnowandlongintothefuture.Ifyouadopttheoutlookthatsafetyistheprimaryobjective,youcaneffectivelydeveloprapportwithcodeofficials.Whentheyandtheirdepartmentknowthataprojectisbeingapproachedwiththeintentofdoingqualityworkandcarefullyconsideringsafety,mostcodeofficialsarehappytodiscussdetailsandhelpfindsolutionsthatmaynotappearinawrittencodebook.Inregardtomasonryheaters,theprincipalsafetyconcernswillalwaysbe

structuralintegrityandfiresafety.Iftheheaterisintendedtobethesolesourceofheatforahome,heatingoutputandefficiencywillalsobeaconsideration,becausemanycodesrequireassurancethataheatingsystemwillmaintainatemperatureofatleast68°Fthroughoutthewinterseasoninthezonedarea.Thisisthepurposeofhavingacompletegraspoftheinformationpresentedinchapters7and8.Structuralintegritymainlyrelatestosoundconstructionpracticesofthefoundation,theheateritself,andamasonrychimney(ifequipped).Itisnottheintentofthistexttoteachordescribecorrectstructuralmasonry

constructiontechniques.Sufficeittosaythatamasonryheaterprojectshouldbeperformedbysomeonefullyawareofsuchpropermasonrymethodsandwillingtofollowdetailsgeneratedbycodeofficialsorengineersinvolvedinaproject.Inseismiczones,inparticular,greatcareshouldbetakentofollowappropriateseismicreinforcingrequirementsofthebuildingcode.Forexample,theInternationalResidentialCode,whichincludesmasonryheatersandhasbeenadoptedateitherthestateorlocallevelinforty-eightoftheUnitedStates,dictatesthatamasonryheatermustbeanchoredtothemasonryfoundationinSeismicDesignCategoriesD0,D1,andD2.Inaddition,ifthemasonryheaterismorethanthreeandahalftimestallerthanitswidth,itmustbeseismicallyreinforced,asitmustifitsupportsamasonrychimney.Thechimneyitselfmustbereinforcedifitsharesafacingwallofthemasonryheateritself.Masonsintheseparticularregionsofthecontinentmustknowhowtoadequatelyperform

thesereinforcements.Thereareadditionalcodeconsiderationsregardingfiresafetyandclearanceto

combustiblematerials.Asnotedelsewhere,themasonryheaterisuniqueinthesolid-fuel-heatingworldwithregardtothewayitburnsandthetemperaturesitachieves.Yetineveryproperlydesignedcase,amasonryheaterhasoutersurfacetemperaturesunder230°Fandusuallyoperatesatexteriortemperaturesmuchlowerthaneventhis.Asmentionedinchapter4,theflashpointofwoodis572°F.Inotherwords,thisisthetemperaturetowhichwoodmustbebroughtinorderforittoburstintoflames.Althoughthenormalaverageoperatingexteriortemperatureofamasonryheaterisonlyaboutone-thirdofwood’sflashpoint,thatdoesnotmeantheheatfromamasonryheater’ssurfacecanneverresultinafire.Whenanobject,likeamasonryheater,iscontinuouslyoutputtingandthereissomeregionintheheaterfromwhichthatheatcannotdissipate,highertemperaturescandeveloptothedangerpoint.Thisisthepurposeofclearanceguidelines.MostclearanceguidelinesappearintheInternationalResidentialCodeas

referencedabove.ThetextoftheInternationalResidentialCode(IRC)referencesthelanguageofASTMInternational’sspecificationE1602,“StandardGuideforConstructionofSolidFuelBurningMasonryHeaters.”Itshouldbenotedbyhomeownersandmasonsalikethatthisisa“standardguide”ratherthananunbreakablesetofrules.Throughoutthetextofthisguideandthebuildingcodearetermssuchas“orasacceptedbytheauthorityhavingjurisdiction.”TheASTMspecificationitselfbeginsbystatingthat,“Itisnotrestrictedtoaspecificmethodofconstruction,nordoesitprovideallspecificdetailsofconstructionofmasonryheaters.”Further,itsays,“Constructionofmasonryheatersiscomplex,andinordertoensuretheirsafetyandperformance,constructionshallbedonebyorunderthesupervisionofaskilledandexperiencedmasonryheaterbuilder.”

WHATISACOMBUSTIBLEMATERIAL?

Topeoplewhoworkwiththetermcombustiblematerialonadailybasis,thisseemslikeasillyquestion.Thetermisnotalwayscleartothelayman,however.Thesurestwaytounderstandthewordcombustibleistotakeitasliterallyaspossible.Verysimply,ifaproductusedforconstructionhas,asoneofitscomponents,amaterialthatwillignite,burn,smolder,smoke,orotherwise

encourageorsupportaliveflame,itisacombustiblematerial.Forexample,manypeoplethinkofdrywall,aproductthatismainlymadefromgypsum,asanoncombustiblematerial.However,mostcommonlyusedgypsum-boardmaterialshaveapaperfacing.Therefore,thisisanexampleofacombustiblematerialthatcannotbeclosertoamasonryheaterthancodeallows.

Nowhere,ofcourse,doesitdefinethispersoncalleda“skilledandexperiencedmasonryheaterbuilder.”Inotherwords,a“skilledandexperiencedmasonryheaterbuilder”canconvincethe“authorityhavingjurisdiction”thatheknowsabetterwaythanwhatisstatedinthecodeorstandard.Indeed,therearewaysofdoingthingsthatarenotmentionedinthesecodesthatarelegitimatewaysofproducingsafeand,perhaps,evensuperiormasonryheaters.Atthesametime,theremaybe“skilledandexperiencedmasonryheaterbuilders”whoreallydon’thavemuchexperiencewithdesigningmasonryheaterswhocanleadbothhomeownersandbuildingofficialsastray.Asalways,laissezl’acheteurprennegardelet—letthebuyerbeware!

ClearancesattheFloorSincemosthomestodayarewood-framedandhavetheirmainfloorsconstructedofaplatformassemblyconsistingofwoodenjoistsorbeams,asubfloorofplywoodororientedstrandboard,andafinishedfloorofthecustomer’schoice(morewood,carpet,orsheetgoods),thisdiscussionassumesafloormadeofentirelycombustiblematerials.Obviously,ifthefloorismadeentirelyofconcreteandfinishedwithceramictile,thereisnocombustibilityissue.Thefirstcriticalintersectionbetweenthemasonryheaterassemblyandthe

combustiblematerialsofthehomeiswherethefoundationpassesthroughthewoodenplatformofthefloorsystem.Asnotedearlier,anall-masonryproject,bybothfireandbuildingcode,iscompletelyseparatedfromthewoodenstructureofthehome.TheIRCrequires2inchesofspacebetweencombustibleframingandthemasonryheaterfoundation.Itispermittedthatthewood-basedsubfloororsheathingextendallthewaytothestructure.Presumably,the2-inchairspaceprovidesenoughaircirculationtopreventthebuildupofheat,whilethesheathingisthinenoughthatitwillnoteasilyaccumulateheat.Thenextmajorconcernatthefloorlevelisthedangeroflivesparks,coals,or

burningwoodlandingonthewoodenfloorandignitingafire.Oneofthesafety

featuresofamasonryheateristhatvirtuallyalldesignsincorporateasolidmetalorglassdoor.Theheaterisnotoperatedwiththedooropen,andthereisnoreasontoopenthedoorinthemiddleofafiringcycle.Therefore,thedangeroflogsrollingoutorsparksjumpingonthefloorisverylow,thoughnotentirelynonexistent.Certainlytherearetimeswhenanownercannotresistrearrangingburninglogsorperhapsopensthedoorbrieflyjusttothrowascrapofwoodonthevigorousfire.Anytimethedoorisopenedtheriskexists,thoughitistemperedbythefactthattheuseristhere,payingattentiontothefire.

FIGURE9.15.Minimumdistancesforhearthextensions.

Regardless,thebuildingcodeseekstofurtherminimizetherisksinvolvedbyestablishingguidelinesforthefloorsurfaceitself.Infrontofthedoorandextendingadistancetoeithersideofthedooropening,theflooringmaterialmustbenoncombustiblematerials.Thisspaceinfrontoftheloadingdooriscalledthehearthextension.The“hearth”isgenerallydefinedastheslabonwhichtheheaterisbuilt,occupyingatleastthesamefootprintastheheater.Thehearthextensionisthepartthatextendsinfrontoftheheater;itisassumedthatthesidewiththeloadingdooristhe“front.”Aheaterwithtwodoors—asee-throughmodel—forpurposesofcodehastwo“fronts”andshouldhavetwohearthextensions.Thisalsoholdstrueforaheaterwithaloadingdoorononesideandabakingchamberonanothersideifthebakingchambercanalsobeusedasacombustionchamber.Morespecifically,formasonryheatersthataredesignedtobeoperatedwith

thedoorsclosed(orwhicharenotoperatedthatway,buthavelargeopeningsgreaterthan0.6squaremetersinsize),thehearthextensionshouldbe20inches

deepandalsoextend12inchestoeithersideofthedooropening(seefigure9.15).Amasonryheaterthatisdesignedtohaveanopenfirebox(unusual)thatislessthan0.6m2insizeshouldhaveahearthextensionatleast16inchesdeepandatleast8inchestoeithersideofthedooropening.Likewise,ifthemasonryheaterincorporatesaraisedhearthorbenchthatisatleast8incheshighandisdirectlyunderthedooropening,theextensiondepthneedonlybe16inches.Insummary,theprincipalclearanceandcodeconcernsatthefloorlevelwith

masonryheatersaretwo:thefoundationoftheheatershouldbeseparatedfromthecombustiblefloorframingbya2-inchspace;andthereshouldbeanextendedhearthofnoncombustiblematerial20inchesinfrontofand12inchestoeithersideofthemasonryheaterdooropening.

ClearancesattheMainBodyoftheMasonryHeater

Bydefinition,masonryheatersaretobedesignedsothatthesurfacetemperatureoftheexteriormasonrydoesnotexceed230°Fundernormaloperatingconditions.Thisdesignparameterdoesnot,however,applytotheloadingdooroftheheater.Consideringthatthefirebox,enclosedpartiallybythemetaland/orglassdoor,containsafirethatmayachievetemperaturesof1,500°to2,000°,itcanbeexpectedthatthedooritselfgetsveryhotandthattemperaturesradiatingfromthedooropeningareawillbeveryhigh.Thereare,then,requirementsforclearancestocombustiblematerialsformostoftheheateranddistinctrequirementsfortheloadingdoor/fireboxareaoftheheater.

ClearancesfromLoadingDoors

Thecoderestrictionsforclearancesdirectlyinfrontofthedoorsstemfromtwoconcerns:firesafetyandpracticality.Sincetheloadingdoorsneedtobeaccessedonatleastadailybasisduringtheheatingseason,itisimpracticaltohavepermanentobstructionsrightinfrontofthedoors.Theguiderequiresthataspaceof4feetalwaysbemaintainedintheareadirectlyinfrontofthedoors.Thisamountofspacemakescarryingwoodtothefireboxpossible.Apersonhasenoughroomundertheseconditionstostandorkneel,openthedoors,andputwoodintothefirebox.Fromthesafetystandpoint,the4-footdistanceislikewiselegitimate.The

glassandmetaltemperaturesinthemiddleofaveryhotfirecanexceed600°F—theequivalentofthebodyofanall-metalwood-burningstove.Obviously,manypeopleoperatesuchstoveswithouthazard.Safetycodeslikethis,however,arenotjustforthiseventuality,butalsoforthefactthatsomeonecouldabusethe

masonryheater.Someonewhodidn’tproperlyunderstandthewayamasonryheaterisoperatedmaycontinuallystokethefireboxwithmorefuel,andtheheatradiatingfrommetalandglasssurfacescouldskyrockettotemperaturesthatcouldignitecombustiblematerialsnearby.ForthisreasonnoprovisionsaregivenintheInternationalResidentialCodeguidelinesfor,inanycase,decreasingthis4-footclearancerequirementinfrontofthedoors.Clearancesfromthedoortocombustiblematerialsinotherdirectionsalso

havea4-footrequirement.However,thereareprovisionsforreducingthatdistance“ifthecombustiblematerialisprotectedbyanengineeredprotectionsystemacceptabletotheauthorityhavingjurisdiction.”Inotherwords,thedoorsofthemasonryheatermaybecloserthan4feettoacombustiblewalltothesideofthedoors,forexample,ifthewallisprotectedinafashionthatsatisfiesthesafetyrequirementsofthelocalcodeofficial.Suchprotectioncouldcomeintheformofasite-constructedheatshielddesignedorapprovedbyanarchitect,engineer,thebuilderofthemasonryheater,orthebuildingofficialsthemselves.

ClearancesfromtheOtherVerticalSidesoftheHeater

Theremainderofthebodyofamasonryheaternevergetsnearlyashotasthedoorsandglass.Nevertheless,the2006versionoftheInternationalResidentialCoderequiresthatclearancesmeettherequirementsoftheNationalFireProtectionAssociationguidelinesknownasNFPA211,Section8–7.Thisisageneralcodeforsolid-fuel-burningappliancesandmakes(asof2006)nodistinctionfortheparticularqualitiesofmasonryheaters.Masonryheaters,then,pertheIRC,mustbeinstalled36inchesfrom

combustiblematerialsexceptwhentheoverallwallthicknessofthemasonryheaterisatleast8inchesthickofsolidmasonryandthetotalthicknessoftheheat-exchangewallsisatleast5inchesofsolidmasonry.The8-inchspecificationappliesmainlytothethicknessofthematerialsthatmakeupthefireboxofthemasonryheater.Ifthefireboxitselfismadewithbricksorrefractoryslabsthatare4inchesthickandtheexteriorsurfaceoftheheaterismadewithmaterialsthatare4inchesthick,thentheheaterisconsideredtohave8-inch-thickwalls.Likewise,ifthefacingmaterialis2½inchesthickandsoisthematerialusedtomaketheheat-exchangechannels,thentheheat-exchangechannelswillhave5inchesofsolidmasonry.Iftheseconditionsaremet,combustiblematerialsmaybeplacedascloseas4inchesfromthebodyoftheheater.Alwaysbearinmind,however,thatinalmostallcases,thelocalbuilding-

codeofficialshavethelastsayinanycodeapplication.Therearethosewhowilllookatwhatisbeingbuiltandsay,“Sorry,thewallisonly7inchesthick.I’mafraidyou’llhavetokeepthatthing36inchesfromanycombustibles.”Thentherearecodeofficialswhowillconsultwiththemasonryheaterdesignerand/orbuilder.Awell-educatedheatermasonordesignerwillknowhowtobuildaheaterthatissafearoundcombustiblematerialsevenifthevariouswallthicknessesdonotmeetthewrittencriteria.Ifsuchabuildercanconveyhisdesignsandshowthathisintentionsandplanswillbequitesafe,thelocalofficialswillusuallybeverycooperative.Likewise—andtheIRCmentionsthis—ifaparticularmasonryheaterhasbeentestedorUL-listedwithreducedclearances,thecodeofficialsmustacceptsuchcertificationsaslongastheheaterisinstalledaccordingtothelisteddirections.Inaddition,somepeoplemaywanttouseamasonryheateraspartofawall

suchthatitcompletelyclosesoneroomfromanother—athrough-the-walldesignsuchaswasmentionedinchapter6.Inthiscase,youwantnoseparationbetweenwallandheater.Thiscanbedone,butnotusuallyinconjunctionwithawallmadewithcombustiblematerials.Forexample,ifyou’dlikethefrontfaceofaheatertobecompletelyflushwiththefaceofthewall(sothatitappearstobepartofthewall),atleastthefirst4inchesofthatwallcomingofftheheatercornersmustbemadecompletelywithnoncombustiblematerialswithathicknessnottoexceed4inches.Ifthewallistocomeoffasideoftheheaterandmorethan8inchesfromacorneroftheheater,itneedstobeatleast8inchesofnoncombustiblematerialandnomorethan4inchesthick.

ClearancestoCeilingsandBeams

Althoughitseemscounterintuitive,thetopsurfaceofmosttallmasonryheatersisoftenoneofthecoolestspotsonthewholeheater.Mostwouldassumethat—sincetheyholdtheideathat“heatrises”—thetopisoneofthehottestparts.Thereasonthatthetopmaynotbeallthathotisthatmostmasonryheatersaredesignedtohavewarm,radiant,verticalsides.Thedesignerachievesthisbydirectinghotexhaustthroughthevariousfluesjustwithinthefacadewallsoftheheater.Whenthetopoftheheaterisrelativelyclosetotheceiling,it’softennotconsideredadvantageoustohaveitbeparticularlywarm.Manymasonryheaters,then,haveinsulationjustunderthefinishingmaterialthatassuresthetopoftheheateriscoolerthanthesides.(Manycustomdesignsdousethetopasanotherhot,radiatingsurface—aswasthecasewiththelittlesoapstoneheaterintheconstructionsequenceofchapter8.Thedecisioninthisregardisbasedon

desiredtotalheatoutputandpracticality.)Regardlessofwhichmethodismostcommon,theInternationalResidential

Codeincludesthetopoftheheaterasapartofthemainbodyofthemasonryheateranddictatesthe36-inchclearancetocombustiblesforthattopsurfaceaswell.Obviously,withcommon8-foot-highceilings,thiswouldrequirethatnomasonryheaterover5feettallcouldbeinstalled.However,asintheprevioussectionrelatingtothemainwallsofamasonryheater,itisrecognizedthatifthereisatleast5inchesofsolidmasonryseparatingtheheat-exchangechannels(flues)fromtheexterior,theclearancedistancetocombustibleceilingmaterialscanbereducedto8inches.This8-inchdistanceisactuallymeasuredfromtheceiling(orbeamor

whatevermaterialisclosest)tothetopsurfaceofwhateverslabs(calledcappingslabs)areusedto“cap”thetopoftheheat-exchangechannels.Somecommonheaterconstructionswillhaveafewinchesofnoncombustibleinsulation,likemineralwool,ontopofthecappingslab,anairspace,thenthefinalheater-topcoveringorslabs.Therefore,basedonthesecoderestrictions,itispossibletohavetheactualtopoftheheaterjustafewinchesfromtheceiling.

FIGURE9.16.Thisheaterisbuilttighttotheceiling.Squareopeningsneartheceilingprovideventilationofthespace.Withoutsuchprovisions,heataccumulatesaroundcombustibleframingmembersoftheceiling.DesignedandbuiltbyStovemaster;photocourtesyofAlexChernov.

Asmentionedpreviously,rulesandcodescanbemanipulatedaslongastheauthorityhavingjurisdictioncanunderstandandbeconfidentthatsafeconditionsarepresent.Itisevenpossibletohavethemasonryheaterbuilttightlytotheceiling.Thisisaccomplishedbytheappropriateuseofinsulatingmaterialsand,also,byventingthecavityabovethecappingslaboftheheatersothatnohotairisevertrappedagainsttheceiling.Ventingisoftenaccomplishedbyleavingoutbricks(orwhateverveneermaterialisused)toasizematchingadecorativegratingmaterial;seetheexampleinfigure9.16.Byhavingatleastoneopenventonoppositesidesofaheater,forexample,freeairflowis

encouraged,minimizingtheamountofhotairthatcanaccumulate.

ChimneyClearancestoCombustibleMaterials

Codeauthoritiesmakenodistinctionbetweenachimneyforamasonryheaterandachimneyforanyotherwood-burningstoveorfireplace.Thefactthatmasonryheatersburncleanlyandproducenocreosoteifproperlyfueledandthefactthattheexhaustfromamasonryheaterenteringachimneyisattemperaturestoolowtoigniteanythingmakesnodifferenceinthefireandsafetyrulesappliedtochimneysthatservicemasonryheaters.Asinmanycodes,therulesappliedtospacebetweenchimneysandcombustiblematerialsaregearedtowardworst-casescenarios:ifcreosoteweretoaccumulateandifthechimneydoesgetsparksorflameinit,thentheremightbeachimneyfire;therefore,therearerestrictionsonhowclosecombustiblematerialscanbetoachimney.Theserulesareoutlinedinthefollowingtwosections.Masonryheatersareconnectedtooneoftwogeneralcategoriesofchimneys.

Eithertheyareconnectedtometal,manufacturedchimneysectionsortheyareconnectedtoamasonrychimney.Sincethetwotypesofchimneyoperateandperformincompletelydifferentways,therearelikewisecompletelydifferentrulesforeachfamilyofflues.

ManufacturedChimneysFactory-manufacturedchimneys,accordingtotheInternationalResidentialCode,shouldbeinstalledaspermanufacturer’sdirections.MostsuchchimneysystemshavebeentestedtooneoranotherUnderwriter’sLaboratorieslistingstandards.Suchtestingisspecifictothewaythechimneyismadewithwhatevercomponentpartsithas.Whenithasachievedtheappropriatelisting,ithasdonesowithallthecomponentpartsassembledasdirectedbythemanufacturer.Theonlywaythesesystems,then,arewarrantedbythemanufacturer(andacceptedbycodeorbuildingofficials)iswhentheyhavebeenproperlyassembledonsiteaccordingtothosesamedirections.Thesedirectionswillspecifyappropriateclearancestocombustiblematerialsgiventheproperinstallation.

MasonryChimneys

Likethemasonryheateritself,amasonrychimney(whichisoftenbuiltrightnexttooraspartofamasonryheater)istohaveapropermasonrysupportstructurewiththesameclearancesandotherparametersasthesupportstructureofthemasonryheater.Therulesgoverningclearancesthroughtherestofthehouse,however,areuniquetothechimneyandcoveredseparatelybytheInternationalResidentialCodeor,usually,anyotherstateormunicipallyacceptedbuildingcode.SincetheIRCistheonlycodestructureincludingmasonryheaters,IRCmasonrychimneyclearanceguidelinesarecoveredhere.Onceagain,youshouldbeawarethatseismicareaswillrequireadditional

reinforcementofmasonrychimneys.TherearespecificanchorageandreinforcementguidelinesinSeismicDesignCategoriesD0,D1,andD2,buttherearenotforSeismicDesignCategoriesA,B,andC.Thesedetailsareparticularlyimportantforatall,massivestructurelikeamasonrychimney.Indoormasonrychimneys,asisalwaysrecommendedforawood-burning

appliance,areexpectedtobekept2inchesfromcombustiblematerialsthroughouttheirheight.Theassumptionhereisthatthisisamasonrychimneywithaclayfluelinerinsideit.Likewise,codewilldictatethatthechimneyitselfwillhaveamasonrywallthicknessof(nominally)4inches.Clay-linedmasonrychimneysarethemostcommon,thoughthereareothermanufacturedoptionsthat,likemetalflues,generallywillrequirefollowingmanufacturer’sdirectionsforproperclearancesandinstallations.Asaclay-linedmasonrychimneypassesthrough,forexample,asecond-floor

level,itwilllikewiseneedtomaintaina2-inchdistancefromthecombustiblematerials.Itisgenerallynotpermittedtosupportwoodframingmembersandotherstructuralaspectsofthehousewiththechimneyunlessithasbeenspecificallydesignedforthatpurpose.Note,however,thatwoodsheathing—liketheplywoodsubflooratthesecondfloor—ispermittedtoabutthemasonryaslongasitremainsatleast6inchesfromtheinsideofthenearestclayflueliner.Thissameruleappliestowoodentrimaroundthechimney.Theactualairspacecreatedbyseparatingachimneyfromaceilingorfloor

structureisalwaystobefireblocked.Fireblockingismaterialinstalledwithinortocoverthespacesoastopreventfirefromhavingeasypassagefromonefloororleveltothenext.Intheeventofafire,anopenaircavityisaninvitationforthefiretorapidlyspreadfromonefloortothenext.Fireblockingseekstominimizethatrisk.TheIRCdoesnotdictateexactlywhatmaterialisusedbutonlysaysthatthesespaces“shallbefireblockedwithnoncombustiblematerial.”

Suchmaterialmightbemetal,cementboard,oranoncombustibleinsulationmaterialsuchasmineralwoolorceramicwool.Itiswisetoconsulttheauthorityhavingjurisdictiontoclarifywhichoftheseisconsideredacceptable.Thissamefireblockingstrategymustbeusedateveryfloororceilingpenetration.

AdditionalCodeRequirementsofNoteThoughthewholeIRCcannotbeexplainedinthischapter,itisusefultolookatissuespertinenttomostmasonryheaterinstallations.Forexample,thoughtherequiredclearancesfromcombustiblematerialshavebeencovered,notyetdiscussedisaverycommonquestion:Howhighabovetheroofmustthechimneygo?Frequently,ifyouweretoasktenmasonsthesamequestion,youjustmightreceivetendifferentanswers.TheIRCmakesitplainandclear.

ExteriorChimneyHeight

Achimneymustbe2feettallerthananypartofthebuildingthatiswithin10feetofit.Atthesametime,thechimneymustbenolessthan3feettallerthanthehighestpartoftheroofthroughwhichitpenetrates.If,say,adormer,orotherpartofthehouseiswithin10feetofthechimneyandhappenstobetallerthanthatchimney,thenthechimneymustbebuilttobeatleast2feettallerthanthatdormer.Likewise,iftheridgeoftheroof,forexample,iswithin10feetofthechimney,thechimneymustbebuiltatleast2feettallerthantheridge.And,finally,ifthechimneyhappenstopassthroughtherooffarfromtheridge(morethan10feet),thechimneystillmustbeatleast2feettallerthanthetallestpartoftheroofplanethatis10feetaway.Seefigures9.17and9.18.Asyoucanimagine,withasteep-pitchedroof,thiscouldmeanthatthe

chimneyabovetheroofcanbequitetall—andmaybespindlylooking—ifitdoesnotpenetratetheplaneoftheroofneartheridge.Thisisyetanotherreasontostriveforpositioningamasonryheaterclosetothemiddleofthehouse.Thechimneywillpassthroughtheroofclosetotheridgeandbeanattractivearchitecturalpiece,ratherthananout-of-placeskyscrapingstructure.

FIGURE9.17.Thischimneyiswithin10feetoftheridgeandsomustbeatleast2feethigherthantheridge.

FIGURE9.18.Achimneylowontheroofmustbe2feethigherthanthehighestpointontheroofplanewithin10feet.Noticehowtallandspindlythechimneycanbecome.

CleanoutAccesses

Chimneysalsoneedtobecleanedfromtimetotime.Buildingcodesrecognizethisneed,andtheIRCdictatesthateverymasonrychimneyshallhaveacleanoutdoororportwithin6inchesofthebaseofeveryflueinthechimney.Themasonryheateritselfshouldalsobedesignedwithsuitablecleanoutaccesses.Whilebuildingcodesdonotspecifylocationsforthesecleanoutsonthemasonryheater,ASTME1602,the“StandardGuideforConstructionofSolidFuelBurningMasonryHeaters,”says,“Ifthedesignlimitsnaturalaccess,installcleanoutopeningsorameansforcleaningallchimneyfluesandheatexchangeareas.”Thisisratherunspecificlanguage.Sufficeittosaythatapersondesigningandbuildingamasonryheatermustcarefullyconsiderhoweveryinternalfluemightbeaccessedforinspectionandcleaning.You’dhatetothinkofamasonryheateronedaybecominginoperablebecauseashaccumulated

somewherethatcan’tbecleaned!

FIGURE9.19.Threecleanoutsarevisibleonthelowerpartofthisbeautifulbrickheater;oneisoneithersideoftheashboxdoor,andoneisatthebaseofthechimneyontheleft.PhotocourtesyofMaineWoodHeatCompany.

OutsideCombustionAir

ThewordingoftheInternationalResidentialCodeinregardtorequirementsforprovidingcombustionairfromoutsidethebuildingformasonryheatersisvagueatbest.TheIRClanguageaddressesoutsideairfor“factory-builtormasonryfireplacesinthischapter[ofthecode].”Itdoesnotmentionmasonryheaters.MasonryheatersarelistedwithinthesameIRCchapterwithmasonryfireplacesandfactory-builtfireplacesbutareclearlyrecognizedasacategorydifferentfrommasonryfireplaces.You’reledtobelievebythecodelanguage,therefore,thatoutsideairrequirementsdonotexist,atleastintheIRC,formasonryheaters.Thebottomlineonthistopicisthattheauthorityhavingjurisdictionin

whatevermunicipalityorlocationatwhichtheheaterisbeingbuiltcandictatewhetheroutsidecombustionairisanecessity.Ihaveseennocompellingevidencesuggestingthatoutsideairiseithernecessaryorbeneficialtotheoperationorsafetyofamasonryheater.Outsidecombustionair,thoughsoundinglikeahighlytechnicalterm,often

simplymeansmanufacturingaleakinthehouse.Manytimesthese“systems”aresimplyair-ventedfromoutsidetoanoutletclosetotheair-intakeareaofthemasonryheater.Asdiscussedinchapter7,theheatingrequirementsforahousearepartiallycalculatedbasedonhow“tight”thehouseis—howmuchhotairislostbyinfiltration.Forallpracticalpurposes,ventsbringingoutsideairintothehousetofeedamasonryheaterarejustholesinthehouseenvelope,intentionallymakingthehouseleakier.Therearehousesthataresocarefullyconstructedandso“tight”thattheydo

notevenprovideenoughairinfiltrationforbasichumanlifesupport.Suchhomesrequiremechanicaldevicestorefreshtheair—typicallyair-to-airheatexchangers.Ithinkthatsuchadesigniscounterproductive.Ahouse,afterall,ismeanttobeaplaceinwhichpeoplelive,rejuvenate,andrecharge.Buildingahomethat,byitself,cannotsustainthatbasicfunctionisfaulty,notsuccessful.Itisasignthatthewayweheatbuildingsnormallyisnotsustainableandbasedonabundant,free,orrenewableenergy,butonfuelsandconditionsthatmustbemeteredandtightlycontrolled.Masonryheatersuseafractionoftheairthatanopenconventionalfireplace

woulduse.Still,amasonryheatermayusearoomfulofairinafiring.Atypicallivingroomvolumemightbeabout2,000cubicfeet.Sothemasonryheateruses2,000cubicfeetofairinatwo-hourcombustionsession.(Youmayrecallthatthesamplehousefromchapter7hadatotalvolumeof10,000cubicfeet.)Well,howmuchairentersahomewhenanexteriordoorisopenedforsomeonetogooutside?Howmuchairdoeseachpersonneedeachday?Mostadultswillneedslightlylessthan400cubicfeetofaireachday.A

familyoffouradultswouldthusrequirenomorethan1,600cubicfeetoffreshaireachday.Together,fourpeopleandalargemasonryheater(iffiredtwiceperday)wouldneed5,600cubicfeetoftotalaireachday.Thesamplehousehadanair-changerateofabout0.5airchangesperhour(ACH).Itisclearthatthe10,000-cubic-foothomegetsnearlyenoughairnaturallyeveryhourforthefresh-airrequirementsforalltheinhabitantsandthemasonryheaterevenifnooneeveropensadoortogooutside!Whowouldwanttoaddanintentionalair

leak(outsidecombustionair)tosuchascenario?Atightlybuilthousemayneedaninterlockedsystemtocompensatefor

excessivedepressurization.Forexample,atighthomewithseveralbathroomexhausts,apowerfulrangehoodexhaust,andperhapsapoweredwaterheaterexhaustcouldbecomeseverelydepressurizedifallormanyofthosefansarerunningsimultaneously.Thiscouldreversethedraftinanotherwiseproperlydesignedandsituatedmasonryheater.Amechanicallyinterlockedsystemherewouldcompensatewithanintakeofairtopreventdepressurization.Thisisintelligentuseofmeteredandcontrolledincomingairtriggeredbytheuseofexhaustfanstoaddressatrue,specific,potentialprobleminsteadofsimplymakinganextraholeinthehouseformoreairtoenter.Onemorepointaboutoutsideairformasonryheatersisthat,obviously,

masonryheatersareusedincoldweather.Theiroperationdependsonhighcombustiontemperatures.Thisgoodoperationisaugmentedbyusingwarm,indoorair.Deliberatelyfeedingcold,outsidewinterairintothefireboxofamasonryheaterservestodecreasecombustiontemperatures—underminingmanyaspectsofthefunctionoftheheaterlikecleancombustionandmaximumheatstorage.Ifgeneraloutdoorcombustionairisaquestionableidea,feedingcoldairdirectlytothefireofamasonryheaterissomethingmuchworse.Unfortunately,thebestsolution,ifoutsideairisrequiredbythebuilding

inspectororthehomeowner,istodirectoutsideairspecificallytothefireboxandnotjustintotheroom.Thiscanbedoneusingatightlyclosing,rubber-gasketeddamperasoutlinedintheconstructionprojectinchapter8.Inthisway,coldairisneverintroducedintothelivingspaceitself,justtothefire.Thesegasketedairsuppliesarealsoavailablewithacomputerizedmechanismthatsensesthedemandforairatthefireandautomaticallyoperatestheairintakeaccordingtotheneedsofcleancombustion.Withthehigh-techaircontrol,theuserneedonlyloadthefuelandlightthefire.Thecomputermonitorsairneedsfornear-perfectcombustionconditionsandautomaticallyclosestheairsupplywhendemandforairdropslowenough.Whetherwithamanualorautomaticcontrol,makingsureanoutsideairsupplyisclosedassoonasitisnolongernecessary(seechapter11)willmaximizetheperformanceundertheseconditions.

CodeFinale

Theentirebuilding-codestructureisdaunting,complex,andoftennotunderstoodevenbycompetentbuilders,letalonethecommonhomeowner.Althoughitisn’tpossible—orevenworthwhile—toquoteandexplaineverypossibleaspectpresentincodesrelatingtomasonryheaters,thischapterhasoutlinedmanyimportantpartsofsafetyandfireissuesthatmostcodeorbuildingofficialswillwanttoknowaredone“right.”Buildingcodesareforsafety.Whenyoukeepinmindthesafetyofyourself,

yourchildren,andfuturepossibleinhabitantsofahouse,itbecomeseasiertopleasethebuildinginspector.Itisalwaysimportanttorememberthatmanybuildingcodesareunspecificandthatspecialcircumstancesorbuildingmethodsoftenarenotspecificallyaddressedinthewrittendocumentation.Thoughmasonryheaters,asacategory,nowappearinthecodesofmanyjurisdictions,eachunique,one-of-a-kindheaterhasitsownspecialattributesandislocatedinonespecificroominonespecifichouse.Thereisnosubstituteforcarefullyconsideringhowamasonryheaterismeanttoperforminaspecificsettingandapproachingthe“authorityhavingjurisdiction”withwell-reasonedwaysofhandlinganysafetyconcernsthatmightexist.

ASTEPBACKINTIME

AccordingtoRitaShort,“Thebestpumpkinpiewehavemadewasmadeinthemasonryheater’sbakeoven.”Shepausesamomentandadds,“Ithadaperfectcrustandwasevenbakedwithoutfoilonthecrust.”Now,ifthatisn’tareasontoaddabakeovenfeaturetoamasonryheater,whatreasoncouldtherebe?Ofcourse,noteveryonelikestobake;or,atleasttheythinktheydon’tuntiltheytastepizzaorbreadorcookiesoutofarealstoneorbrickoven.Suddenlytheydevelopadesiretomix,knead,roll,proof,andbake.RitaandWendellShortlivewiththeirtwochildrenoutsidethelittletownof

Archbold,innorthwestOhio.Archboldisknownforitsquaintnessandforitshistoricattraction,SauderVillage—afarmsteadwhereyoucangotoseehowlifewaslivedinthe1800s.SauderVillageisnamedforErieSauder,awoodworkerwhostarteda(then)littlecompanycalledSauderWoodworking,nowaleadingproducerofready-to-assemblefurnitureintheUnitedStates.WendellShortisdirectorofnewproductdevelopmentatSauderWoodworking.Insomerespects,itseemslikesteppingbackintimetovisittheShorts’

homesteadinthecountry.Onthehillisabigoldbarn.Chickensrunaroundtheyardandunderthepeartreesjustinfrontofthehouse.Thehouseitself,though

justcompletedtenyearsago,looksoldaswell,atleastindesign.Ifyoulookclose,youseethehomeboastshigh-efficiencywindowsandcementboardsidingandmanyotherqualityfeaturestoguaranteedurabilityandlongevity.Whenyoustepintothefrontporch,youfindhundred-year-oldbarntimberssupportingtheroofofthefour-seasonroom.Openonemoredoorintothemainhouseandthefirstthinginviewisamassivebrickmasonryheaterwithanarch-topdoorandwide,inviting,raisedbrickhearth.WhenWendellandRitahadtheheaterbuilt,theyorderedrecycledbricksandwanteditto“looklikeithadbeenthereahundredyears.”That’sjustthewayitlooks.Thelookisperfectforthehome,halfofwhichisawarmandinvitingtimber-

framemadewithrecycledDouglasfirtimbers.Overthelargetimberfloorjoistsisaceiling(whichdoublesastheupstairsfloor)ofpinebarnsidingpaintedalusciousdarkgreen.Thepinkishorangeoiledwoodgoeswellwiththeoldredbricksoftheheater.Theotherhalfofthehouseisactuallyan1800sloghomethattheShortsrelocatedfromanotherpartofthepropertyandaddedontotocreatetheiruniqueresidence.Thedecisiontohaveamasonryheaterstartedforthemwhentheywere

perusinghome-buildingmagazinesandspottedanadvertisementforamasonryheater.Wendellexplains,“Thethingthatsoldusontheconceptwastheefficientcombustionwithverycleanemissions—thuskeepingthechimneycleanandeliminatingtheriskofchimneyfires.Wehadachimneyfireinanolderhomewithawoodstoveinsertinanoldfireplace.Itwasnotagoodexperienceotherthanwegottomeetthefiredepartmentandacoupleneighbors.”Thecouplehadjustmovedintotheneighborhoodafewmonthsearlier;thechimneyfirewasnotexactlythehousewarmingtheyhadanticipated.

FIGURE9.20.Thisheaterwasbuilttolooklikeithasbeenusedforahundredyears.PhotobyWendellShort.

Andsoitisthatmanymasonryheaterownersappreciatetheirinvestmentforitssecuritybenefits.TheShortshadverylittleexperiencewithwoodheatingotherthanthemishapwiththestoveinsert.Theirprevioushomeshadforced-airorconventionalradiators.Ritarelates,“Wefound,fromourpriorhomes,thatwelikedthewarmthofradiantheat,butwantedsomethingmoreefficientandthatworkedwithoutelectricity.Itisgreattonothavetoworrywhenthepowergoesoutonacold,wintrynight!”Chalkupanotherpointforsecurity.It’snotjustsecuritythattheyenjoy,however.Norjustthepumpkinpiesthat

comefromtheoven.Rita,whohomeschoolshertwoboys,relatesthatthehillonwhichtheirbarnsitsisalsoanattractioninthewinterforkidsandtheirsleds.“Theneighbor’schildrenliketocomeandsleddownourbarnhill.Afterwardtheycomeintoplayandwelinetheheaterwithsnow-coveredsnowbibs,coats,scarves,mittens,andboots.Bythetimetheyarereadytogohometheirclothesandbootsarewarmanddry.”Soisitanoven,afireplace,aheater,oraclothesdryer?Apparently,it’salloftheabove.Bothagreethat,thoughhauling,splitting,andstackingwoodisstrenuous

work,ithastheother-side-of-the-coinbenefitofjustplaingettingthemoutof

thehouseandgettingsomefreshairandexercise.Wendellcomments,“Thisisagreatwaytoworkoffthestressoflonghoursintheofficeduringtheweek.”It’sclearthatbothofthemcanseeasilverliningineverycloud.Therestofthestoryofusingwoodinamasonryheater,however,isthat“Weusealotlesswoodthanothersweknowwhohavearegularfireplaceorawoodstove.”Imaginesplitting,hauling,andstackingeightcordsofwoodinsteadofthefourorsothatWendellandRitagothrough!TheShortsneverdidinstallabackupheatingsystem.Theydependentirelyon

themasonryheater.Theycommentthatthislimitstheirabilitytotravelinthewintertime,buttheyadmitthatwastheirdecisionandthatitisnotforeveryone.ButlikethesettlersofnorthwestOhiointhe1800s,WendellandRitahavemadethemselves100percentresponsibleforhavingheatinthehouse.Intheirownway,theyarepioneers,too.

W

PARTFOUR

LivingwithaPieceoftheSun

ell,it’sdone!Thecarefuldesignwasexecutedintheperfectlocation.Materialswereselectedandpurchased.Codeswereconsulted.Theinner

lifewasdesignedandputinplace.Themasonryheaterwasbuilt.Nowwhat?Ifyourandomlyaskedpeopleonthestreethowtodriveandcareforacar,

theycouldprobablygivedetailedinstructionsonhowtodoeverythingfrominsertingthekeyintheignition,toreplacingwindshieldwipers,tochangingtheoileveryfewthousandmiles.Ifthesesamefolkswereaskedhowtooperateandmaintainamasonryheater,however,theywouldlikelyask,“Awhat?”MasonryheatersarenotyetcommonenoughinNorthAmericathatpeopleknowhowtousethemtobestadvantageandwiththeleasteffort.Easilythesinglemostimportantfactoringoodoperationofamasonryheater

istherightfuel.Chapter10coversinsignificantdetailhowtoobtainwood,howtostoreit,andhowmuchofittosetaside.Chapter11isaguidetousingatypicalmasonryheater,includingcookstovesandheaterswithbakingovens.Thisincludesinformationaboutbreakinginanewlyconstructedheater,andthesimpletaskofburningdailychargesoffuel.Thefinalchapterexplainshowtomaintainamasonryheater.Livingwithamasonryheateristheeasiestpartofthewholerangeoftopics

coveredinthisbook.Thework,theplanninganddesigning,thelocating,theselectingofmaterials,shapes,andoptionsarethehead-scratching,time-consumingpartofgettingtothepointoffirstuse.Owners-to-besometimeswillspendweeksormonthsselectingthecolorsforamasonryheater.Butlivingwithoneisprimarilyasimpleactofenjoyingfireandwarmthwithfamilyandfriends.Noneoftheenjoyment,however,ispossiblewithoutfuel.

FIGURE10.1.Astuccoheatercentrallylocatedinthehome.Theloadingdooratlowerleftisatwaistlevelforeasyloadingwithoutbendingover.Niches,shelves,andcurvedelementsaddvisualinterestandaplacetosetdecorations.PhotocourtesyofBiofire,Inc.

CHAPTERTEN

FueltoBurn

Realenergyisfree.Itisfreeforthosewhoplan,prepare,andareaware.Eachday,412BTU/hrpersquarefoot(1.36kW/m2)ofenergyreachestheearthfromthesun.Inchapter7,ourhypotheticalhouserequired13,600BTU/hrforheatingpurposes.Thesun,therefore,freelysendstoearthenoughenergy,ina33-square-footarea,toheatthathome.Inotherwords,thereisenoughpowerreachingtheearthfromthesuneveryhouronanareathesizeofasheetofplywoodtoheatawell-insulated,1,000-square-foothomeinnorthernOhioforonehour.Despitethiswell-documentedfact,weliveinasocietythatcallsanatural-gas-burningfurnaceamoderntechnologicalwonder.Asasociety,wehavenotyetadvancedenoughtoknowthatrealenergyisfree.Thegasfurnacerequiresyoutobeconnectedviapipelines,trucks,refineries,

andwellsatvastexpenseforconstruction,maintenance,andcontinuedexploration.Allthesecostlydependenciesappearinamonthlybillforservicesandproduct.Ifapipelinebreaks,thereisnofuel.Ifawellgoesdry,thereisnofuel.Iftheelectriclinesbreak,thefurnacewon’twork.Ifafusebreaksinthehome,thefurnacewon’twork.Myriadothertechnologically“advanced”partsbreak,wearout,andfail.Allthisexpense,dependency,andriskrevolvearoundthemosttechnologicalsolutionsdevelopedinthemodernworldforheatinghomes.Whilehumandependencylingers,thesuncontinuestosenditsfreeenergytotheearth,justbeggingustouseit.Ofcourse,solarenergyitselfremainslikewiseelusiveandundependable.Itis

likelythatifyoucouldalwaysdependonthesuntoshineinaclearskyeverydaythroughouteverywinter,bynoweveryonewouldhavesomekindofsolar-poweredhome.Thatisobviouslynotthecase.(Infact,eveninsouthernclimateswherethesundoesdependablyshinevirtuallyeveryday,solarenergyisstillusedmuchlessthanitcouldbe.)InthecoldnorthernareasofNorthAmerica,wintersunshinecanbeveryfleeting.Daysofglorious,clearskiesaresometimesfollowedbymanydaysorevenweekswhenyou’dthinkcloudcoverispermanent.Asgreataspuresunshinecanbe,itisnotthefinalsolutionuntilagoodwayisfoundtostorethatabundantenergyforarainy(orsnowy)day.

WheneverIgoouttomywoodshed,Imarvelthatnaturenotonlysendsallthefreeenergytotheearth,butalsoprovidesthefreebatteriesforitssnowy-daystorage.Eachair-driedpoundofwoodstores6,400BTUsofsolarenergy.Asingleoaklogcontainsover30,000BTUs.Holdinga5-poundoaklogislikeholding60squarefeetofsunshineinhand(becausethatonelog,whenburnedefficiently,willreleaseabout1,000BTUsperhourthroughanefficientmasonryheater).Thusfreedfromconcernoverthepresenceornotofthesun,anownerofamasonryheaterenjoysthesun’sradiantheatevenonthoseinnumerable,cloudydaysofwinter.Itwouldbenaive,however,topretendthereisnodependenceatall.Even

whenfoodisacquired,cooked,andplacedonatableinfrontofyou,youstillneedtoliftaforkandknife,cutthefood,andputitinyourmouth.Youneedenergytokeepthehousewarmandsomustaccumulatethebatteriesofheatjustasothersaccumulatethedollarstopayforgasorfueloil.Thedependencenow,however,isonyourself.Whoismoredependablethanyourself?Asfreeastheenergymaybe,youstillneedtogooutandgatherit,prepareit,andhouseitsothatitisreadyforwintertimeuse.

HowMuchWood?

Chapter7discussedhowtocalculatetheheatneededinagivenhouseorroombeingheatedbyamasonryheater.TheresultsdevelopedasatotalnumberofBTUsperhourneededinanyparticularlivingspace.Thistotal,however,wasatotalforthecoldestdayoftheheatingseasonforagivenlocationinahomewithspecificconstructionattributes.Thissinglefigure,thoughcrucialfordeterminingwhatsizemasonryheatertobuild,doeslittletoexplainhowmuchheatthehomeneedsthroughthewholeheatingseason.EspeciallyinthenorthernpartsoftheUnitedStatesandintoCanada,the

heatingseasonwilleasilylastsevenmonthsormore.Thatcoldestday,whichoftenoccursinJanuary,ismonthsawayfromboththebeginningandendoftheheatingseason.Ifyou’vetakenthetimetodiscoverhowmuchheatyouneedonthecoldestdayanddevelopedthedesignforamasonryheater,itstandstoreasonthatoneofthenextquestionstoanswerwillbehowmuchfirewoodyouneedfortheentireheatingseason.Infact,it’sagoodideatobeginaccumulatingheatingfuelassoonasyouknowthehousewillbeheatedwithwood.Thatway

itwillhavemaximumtimetoseasonproperlybeforeyouuseitinthenewlyconstructedmasonryheater.Thebestwaytogetagoodestimateofthetotalamountoffuelyou’llneedis

torefertoachartofthetotalheatingdegreedaysforthetownormunicipalityclosesttothehouse.Aheatingdegreedayisthenumberofdegreesthataday’saveragetemperatureisbelowthetemperatureatwhichbuildingsneedtobeheated.Usually,itisassumedthatyoubeginheatinganytimetheoutdoortemperatureisbelow65°F.Forexample,ifageographiclocationaverages35°onDecember1,thenitsheatingdegreedays(HDD)forDecember1are30.Ifthatareaaverages35°forthewholemonth(thirty-onedays),thenthetotalHDDforDecemberare930.TotalheatingdegreedaysforawholeseasonarefoundformanyareasinappendixD.Continuingthesampleprojectbeguninchapter7,thetotalfirewoodneedsfor

the1,000-square-foothomeinClevelandcanbeestimatedasfollows:first,itwasestimatedthatthetotalheatloss(THL)ofthishouseis269.26BTU/hr-°F.Multiplyingthisnumberby24givestheTHLforawholeday(per°F)insteadofperhour.(Notethatthiscalculationisnottakingintoaccountpossiblesolargain,heatgainfromlivinginhabitantsandappliances,andsoforth.Thepurposehereistohaveagoodminimumestimateofhowmuchfirewoodislikelytobeneeded.Itisneverabadideatooverestimateinthisregard,forit’smuchbettertohavemorewoodthannotenoughastheheatingseasonprogresses.)Thecalculationis:

24hr×269.26BTU/hr-°For6,462.24BTU/day-°F

ConsultingappendixD,wefindthatthetotalheatingdegreedaysforClevelandis5,717inthewholeheatingseason.BysimplymultiplyingtheTHLbythetotalHDD,anumberrepresentingtotalseasonBTUsisobtained.Inthiscase

6,462.24BTU/day-°F×5,717°F-day=36,944,626BTU

If1poundofair-driedwoodcontains6,400BTUs,thishousewillneed

36,944,626BTU÷6,400BTU/lb=5,773poundsofwoodforoneyear

Table10.1indicatesthateverycordofair-driedsilvermaplefirewoodweighs2,970pounds.Simplydividingthetotalpoundsneededbytheweightofacordprovidesthetotalestimatednumberofcordsneeded.

5,773lbs÷2,970lb/cord=1.94cordsofsilvermaple.

Inthiscase,you’dbewisetohave2cordsofmapleonhandfortheheatingseason.Ifyouareplanningtostockpileoak,adenserfirewood,lesstotalcordageofwoodwilldothesamejob.Acordofwhiteoakweighs3,863pounds.Theheatingforthishousewilllikelyrequire

5,773÷3,863=1.5cordsofwhiteoak

Althoughthesecalculationspurporttodeterminehowmuchwoodisneededforagivenlivingspace,rememberthatthenumbers—especiallytheheatingdegreedays—arebasedonhistoricalaverages.Bothhistoryandaveragesare,bynature,notindicativeofwhatmayhappeninagivenyear.Additionally,theHDDfigure,intheUnitedStates,iscommonlybasedonapresumedindoorairtemperatureof65°F.Ifthehomeorlivingspacewillbekeptwarmerthanthat,theactualamountoffuelusedmayincrease.Whenyouaresolelyresponsibleforaccumulatingheatingfuel,itisalwaysbettertoplanfortheunexpectedandhaveextraonhand.Anyextra,ifstoredproperly,isneverwastedandcanbethesafetynetforthenextheatingseason.

Table10.1.Approximateweightperstandardcord(80cubicfeetofsolidwoodcontent)ofvariouswoods(greenandair-driedto20-percentmoisturecontent)andpotentialheatofair-driedwood.

Approximateweightofstandardcord(occupying128cubicfeetofspaceandcontaining80cubicfeetofsolidwood),forthefirsttwocolumnsoffigures.*To20%moisturecontent***Potentialavailableheatfromstandardcordwith100%unitefficiency.Heatat20%moisturecontent.Reprintedfrom“WoodFuelforHeating”byJohnP.Slusher,SchoolofNaturalResources,UniversityofMissouri-Columbia,1995(1985).

AcquiringFirewood

Knowinghowmuchwoodyouneedeachyearisjustastart.Thetaskistogetthatamountofwoodinstoragelongbeforeyouneedit.Thereisnojoyinhavingabeautifulmasonryheaterinstalledbutnofuel,oronlyinadequatelyseasonedfuelwithwhichtowarmit.It’slikesalivatingforaporterhousesteak,thenhavingthewaitresstellyoutherestaurantjustcookeditslastonefortheguyacrosstheroom.Beingresponsibleforyourownfuelsupplyisverydifferentfromthedependency-inducedcomaofjustsettingthethermostatto

“auto”whentheweatherturnscool.Youmustthinkahead.Aslongasyoudothat,thetaskitselfisn’ttoohardforanyonetohandle.Everyonefrompetiteladiestohuskymencansecureaseason’sfirewoodusingtoday’smodernconvenienceslikechainsawsandpickuptrucks,thoughyouneednotowneithertoeffectivelyandinexpensivelyheatwithwood.

OwntheLandThereisnobetterguaranteeofhavingfreefuelthanhavingwoodedproperty.Thosewhoareplanningandareawareofthepossibilitiescan,indeed,havefirewoodfreeforthetaking.Whilegeologistsmustspeculate,test,andeventuallydrillinthehopeoffindingadequatesuppliesofgasandoil,anownerofrealpropertyonlyneedstolooktoseeboththeforestandthetrees.Thepropertyownerwitheyesknowsinaninstantifthereisfuelontheland.Awoodedpropertyofjust10acrescankeepyousuppliedwithwoodonasustainable,lifelongbasis.Anacreofwoodedpropertywillgrowaboutone-thirdofacordofwoodperyear.Ifwellmanaged,10acreswilladequatelyyieldbetween3and4cordsofwoodeachseason.Usingoursamplehome,wedeterminedthatabout2cordsofmaplewouldbe

anadequatesupplyofwoodforthishouse.Inthiscase,a6-acrewoodedlotbrimmingwithmapletreeswillsupplyyouwithalifetimeofsolarbatteries.Woodsthathaveneverbeenmanagedatallmaycontainseveralyears’worthofdeadtreesorstandsthatdesperatelyneedthinning.A10-acre,previouslyunmanagedparcelcouldhaveasmuchas6cordsofwoodthatcanberemovedwithoutaffectingtheabilityofthatwoodlottoproduceathirdofacordofwoodperacreeachyear.Inthisway,thepersonwhoonlyneeds2cordsperyearcouldsecureathree-yearsupplyjustbythinningandcleaningoutthewoodsthefirsttime.Bythetimethisownerhasconsumedhisfirst6cords,the10-acrewoodswillhavealreadygrownanother10ormorecordsofwood.

FIGURE10.2.Althoughonlythesoapstoneheaterinthemiddleofthepictureretainsheat,theuseofsoapstoneslabsforseatsandsoapstonetilepiecesforaccentscreatestheimageofamuchlargerheater.Noticethesoapstonetileclockandsoapstonegobletsattopcenter.Thewingbencheshavewoodendoorstoopentoaccessfirewoodorotherstoreditems.PhotocourtesyofTulikiviCorporation.

Eventhosewithsmallerparcelsofwoodedlandcansupplementheatingwiththewoodthereon.Asingleacre,wellwooded,willannuallydropbranchesandtwigsthatareusefulforfirestarting,prewarmingamasonryheater,orevenfiringsmallmasonryheatersandcookstovesformuchoftheseason.Likewise,neighborswhodonotburnwoodmaybethrilledtohavesomeonetakefallenbranches,twigs,andevenunwantedtreesofftheirland.Ofcourse,plentyofmasonryheaterownerswillhavesmallerlotswithonlyafewtrees.Theywillnotbefuelself-sufficient.Anotherwayto“owntheland,”however,istobecomeawareofpublicly

ownedforestinthevicinity.Taxdollarspaytomaintainandsupportthesepublicforests,sowhynotmakeuseofthelandofwhichyou’repartowner?Varyingfromstatetostateorprovincetoprovince,manypublicforestsdoallowlimited

removalofwoodforfuel.Sometimestherewillbealicenserequirement.Thinkofthisasbeingtheequivalentofahuntinglicense,exceptthatinsteadofhuntinganimals,itistreesthatyou’restalking.Justlikethehuntingequivalent,suchanarrangementfrequentlywillallowonlyacertainamountofwoodtoberemovedperpermitholder.Youneednotfretifthese“owntheland”optionsdon’tworkinaparticular

area,however.Therearestillmanyotherwaystofindandacquirewoodforamasonryheater.

LandscapeandTreeServicesInmanyways,localandregionallandscapeandtree-servicebusinessesarebetterthanowningyourownwoodlot.Withinacity,inparticular,thosehiredtoremovetreesfromhomesitesaresometimesdesperatetofindplacestodumpallthewood.Althoughitisnottrueinallcases,someofthesebusinessesdonothavethenecessaryspaceandinfrastructureforkeepingthecutwood,splittingit,andstoringitwhileitisadvertisedtosell.Suchoperationswillbehappytoknowofplacestheycantakethewoodanddumpit,andtheywilldoitatnochargetotherecipient.What’smore,theyoftenwillcutmostofthelargerpartsofthetrunkintoshort,commonfireboxlengthsof16to20inches.Likewise,ifsuchacompanyisseeninaneighborhoodworkingattree

removal,itisalwaysworthwhiletostopandtalktotheforemanaboutthepossibilityofgettingthewood.Especiallyifthetripisshort,theymaybequitehappytoknowofaplacetotakeit.Inaddition,manyoftheseserviceswillmulchevenlargebranchesof3to4inchesindiameter.Suchtimberisperfectfuelformostmasonryheaters.It’spossiblethetreeservicewillgladlyskiphandlingallthatextrawoodandjustsenditalongwiththeprimarylogsuponrequest.Thedownsideofthisoptionisthat,already,moreandmorepeopleare

burningwoodandaremakingthesamearrangements.Theremayactuallybeawaitinglistofpeoplewhowanttogetwoodfromatreeservice.Inthiscase,thelikelihoodofgettingthisfreefuelmaybesmall.Theservicemaybegindeliveringonlytothosewhoareonthelistandwhoarewithincloseproximitytotheplacefromwhichthetreeisremoved.Thebesthedgeagainstthisistomakesurefriends,relatives,andacquaintancesknowthat,iftheydon’twantthewoodfromatreetheyarehavingremoved,youdo.Usually,peoplewhohirea

servicetocutatreecanrequestthatitbetakentoaspecificplace.Afterall,it’stheirtree!Theownerofthetreecanmakesurethatspecificplaceisyourhouse.Finally,somelandscapeandtree-servicecompanieswillactuallysellwhat

theycall“limbwood.”Becauseveryfewwoodstoveownershaveaninterestinsmalllogsandlimbs,theseservices,iftheydonotmulchallthesepieces,willsometimessellapickuptruckloadofperfectlygoodmasonryheaterfuelataverylowcost.

SawmillsandCabinetmakersOneoftheabsolutebestvaluesinfirewoodformasonryheatersisthesawmillslabsatlocalsawmills.Small,regionalsawmillsoftenprocesshardwoodsforlocalandregionalindustrieslikewindow,door,andcabinetmakingcompanies.Everytimeasawmillprocessesarawlog,oneofthefirstoperationsisto“slab”it.Thismeansthatthenaturallyroundlogissawnonfoursidestomakethelogsquare.Inoneoperation,thisprocessremovesbark,wane,andsapwood—allthe“undesirable”partsofanotherwisevaluablelengthofwood.Sincetheseslabsareuselesstothemillformakingboardsthatmaybecomeflooring,window,door,orcabinetlumber,themillwilloftenbundlelargequantitieswithbandingandsetthemasideasjunkwoodforsale.Ofcourse,this“junk”woodburnsjustaswellasanyotherfirewoodina

masonryheater.Nonetheless,thosewhoownmetalwoodstovesandconventionalfireplacesaregenerallynotattractedtotheseslabsbecausetheyarethinboardsratherthanthicklogs.Inanyapplianceinwhichthegoalistokeepafirealwaysburning,suchthinpiecesofscraparenotatopchoice.Theirlossisthemasonryheaterowner’sgain.Ihavepurchasedhugebundlesofthesesawmillslabs—roughlytheequivalentofacordofwood—foraslittleas$15!Somemillswillevendeliverthesebundlesatanominalcostifmorethanacouplearepurchased.

FIGURE10.3.Thistile-and-stuccoheaterhashandmadeandhand-paintedtiles.Boththeseatandthemassbehindthetiledfireboxareforheatstorage.Kachelofendesigned,built,andphotographedbyErnstKiesling,CanadianKachelofen.

Thesebundlesofslabsaresometimes8,10,or12feetlongand4or5feetindiameter.Frequentlytheyareheldtogetherbymetalstrapping.Thismakespreparingthewoodforstorageveryeasy.Yousawthroughthebundleofwoodwhileitisstilltogether,makingthepieceswhateverlengthyoulike.Someslabsmightbequitewide—10or12inches—andcanbeeasilysplitonceifdesired.Otherwise,thesethinslabswilldryrelativelyquicklyifproperlystackedandstored,andmakeexcellentmasonryheaterfuel.Inasimilarfashion,companiesthatactuallymakefinalwoodproductslike

cabinets,doors,windows,orfurniturewilloftenhaveascrappileofrejectedwoodandvariouscutoffsorrippedlengths.Forexample,afurnituremakermayneedboardsthatareexactly4incheswide.Theymayorderlumberthatis10incheswide(ormore)sothatthewoodcanberippedintotwoboardsatthedesired4inches.Theremaining“rippings,”ofjust1or2inches,maybecompletelyuselessandrelegatedtothescrappile.Veryoftenthesescrappilesareavailableforthetakingforanyonewhoinquiresfirst.

PalletandConstructionScraps

Oneofthesimplestwaystogetfreewoodistofindalocalbusinessthatreceivesshipmentsonwoodenpalletsorinwoodencrates.Palletsandcratesareeasytobreak,pry,orcutapartandusuallyofferdrywoodthatisreadytoburn.Alocalestablishmentthathasnousefor(oranexpenserelatedto)suchpalletsisoftenlookingforwaystogetridoftheexcessmaterialandmayevensavethem

specificallyforsomeonewhoofferstocomeonaregularbasisandtakethemaway.Evenplacesthatnormallyrecycleorreusecratesandpalletswillhavesomethataredamagedandnotworththeirtimetorepair.Ioncesuppliedmywholeheatingneedsforanentireseasonusingwood

scroungedinthisway.Alocalsteelplant,onadailybasis,wasdiscardinghundredsof8-foot-long2-by-4sthathadbeenusedasshippingmaterialforitsproducts.Theplant’spersonnelhauledalltheseperfectlygood(forfirewood)piecesofwoodtothedumpsterwhenceIretrievedthembythedozen.InveryshortorderIhadaccumulatedseveralcordsofwood.Theonlypreparationthiswoodneededwastobecuttolength.OnlyveryrarelydidIfindnailsorotherfastenersinit.Itshouldbeclearthatonlysolid-woodcratingshouldbeviewedaspotential

firewood.Plywood,particleboard,andorientedstrandboardcontainersshouldnotbeusedforfirewoodbecausethevariousgluesandadditivesintheadhesivesusedintheseproductscanbehighlytoxicwhenburned.Alsoavoidpressure-treatedwood,whichlikewisecontainsharmfulchemicals.Mostpallets,however,aremadewithsimple,sawnwood.Somewillevenbeoakorotherhardwoods.FIGURE10.4.Afloor-to-ceilingandwindow-to-windowstonemasonryheater.Tightjointsonthestoneworkareahallmarkofgoodcraftsmanship.PhotocourtesyofEmpireMasonryHeaters,Inc.

Likewise,constructionscrapsareperfectlysuitableforfuelingamasonryheater.Mostlumberusedtodayinhomeconstructionisdimensionalsoftwoodlumbersuchas2-by-4s,2-by-6s,andthelike.Ontheotherhand,youcanalso

stumbleuponscrapsfromhardwoodflooringandtrimtoaddtothehardwoodcollectionoffirewood.Asinpalletsandcrating,youshouldavoidplywood,laminatedbeams,andothermanufacturedwoodproductsthatwillhaveapreponderanceofadhesives.Alsobeveryconsciousofthehazardthatnailspresentwhengatheringthesescraps.Bothconstructionscrapsandpalletsorcratingareexcellentfuelsformasonry

heatersbecausethelumberisgenerallysmall-dimensionedanddry.Suchwoodisperfectforthehot,relativelyfastfireinproperlydesignedandoperatedheaters.Ownersofmetalwoodstovesandregularopenfireplacesarenotsointerestedintheseoptions,normally,becausethissmallwoodisnotlonglastinginafireandcanthereforeaddtothenuisanceofconstantreloadingoffuel.Again,theefficient,fast-burningmasonryheateroffersanadvantagewhenitcomestogettingthisdiscardedfirewood.Therearesomeadditionalcautions,and,perhaps,disadvantagestosuch

material.Oneisthatpallets,inparticular,areloadedwithnailsorstaples(whichareoftenpresent,asnoted,inconstructionscrapsaswell).Veryindustriouspeoplemaygotothetroubleofcompletelydismantlingpalletsandremovingallnailsintheprocess.Thosewhowishtosalvagetheirfirewoodwithoutusingpowertoolsmayfindthisworthwhile.Thosewhowanttomakethejobquick,however,willsimplysawthepalletsapartwitheitherachainsaworanelectriccircularsaw.Inthelattercases,allthenailswillgothroughthecombustionprocessofthe

masonryheaterandendupintheashes.Thisisnoproblemiftheashesaregoingtobeeventuallybaggedanddiscarded.(Caution!Hotashesshouldalwaysbecooledinametalcontainerbeforebeingbaggedfordisposalviagarbagepickup.)However,ifyouwishtousetheashesinthegarden,orspreadthemonanicydriveway,you’llhavetoremovethenailseitherbyscreeningorwithamagnet.Otherwise,theywillbeaconstantsafetyhazard.Theothercaveatwithconstructionandcratingmaterialsistowatchoutfor

chemicallytreatedwood.Mostpallet-makingoperationsaremeanttobelow-budget.Afterall,themakersofpalletsandcratingknowthattheirproductisgoingtobeused,perhapsreused,eventuallywillbreak,andthenwillbediscarded.Thereisnoincentiveinthisbusinesstousespeciallytreatedwoodinmostcases,thoughit’snotimpossibletofindpalletsmadefromtreatedwood.Forexample,palletsthatareusedforinternationalshippingarerequiredtomeetInternationalPlantProtectionConvention(IPPC)rulesthataimtoprotect

againstthemovementofinvasiveinsectorplantspeciesfromoneinternationalregiontoanother.Someofthesepalletsarethereforetreatedspecially;anysuchtreatmentismarkedonthepalletitself.Onewaythesepalletsaretreatediswithheat.Thepalletitselforthematerials

usedtomakeitaresubjectedtotemperatureshighenoughtokillanyinsects,insecteggs,orseedsfrominvasiveplantspecies.Ifacratingmaterialissoheat-treated,itwillbestampedwithanIPPClabelwithanHTdesignation.IftheIPPClabelcontainstheMBdesignation,ontheotherhand,ithasbeentreatedwithmethylbromide,apesticideofrelativelyhightoxicity.Methylbromideisagasusedasafumigant,notasapenetratingliquid.As

suchitdissipatesquicklyandsubstantiallyandisthoughttoposenotoxicriskviathematerialssotreated.Infact,methylbromideoccursnaturally;theoceansoftheworldarethemajorsourceofthisgas.However,peopleconsideringburningpalletstreatedthiswayshouldbeawareofitsexistenceanduse.CratingtreatedwiththischemicalhasnodistinguishingcolorsormarkingsotherthantheIPPClabel.Ifitislocallymadeandjustlookslikecleanwood,itprobablyis.However,thereisnosubstituteforinvestigationifyouhaveanyreasontobelievewoodhasbeenchemicallycontaminated.FIGURE10.5.Alargesoapstoneheatersitswellcenteredbetweenadiningandlivingroom.Thestone-wrappedchimneyrisesneartheridgeofthecathedralceiling.Theheaterfeaturesrock-facedsoapstone“bricks,”wraparoundmantelandbenches,andagreenserpentinearchoverthedoor.PhotocourtesyofTulikiviCorporation.

Otherlumberthatischemicallytreated,asinconstructionscraps,usuallybearsanobviousunnaturalcolorsuchasthegreenishtintofwhatiscommonlyreferredtoas“treatedlumber.”Thistypeoflumbermaycontainahostof

chemicalsthatalsoshouldnotbeburned.Thedistinctiveappearanceofthiswoodwhendiscardedatabuildingsiteishardtomiss,sowoodscroungersshouldsimplyavoidit.

TheOld-FashionedWay:BuyIt

Therearemanypeoplewhosimplywillnotbeinclinedtodotheworkofsecuringtheirownfirewood.Timeconstraints,physicalrestrictions,familycommitments,anddozensofotherreasonsexistforapersontochoosethe“easy”wayout—justbuythefuel.Thelandscapeandtree-servicecontractorsmentionedearlierinthischapter,if

theyhavethespaceandpersonnel,willoftensellfirewoodthey’veretrievedfromtheirservices.Likewise,thereareentrepreneurswhoalreadyhaveaconnectioninonewayoranotherwithsuchservicesandregularlycut,split,andmakeavailablewoodforsale.Ofcourse,therearealsothosewhoownalotoflandorhavepermitstoaccesspubliclandsforacquiringfirewood.Ingeneral,inanyareaofNorthAmericainwhichtherearetrees,thereislikelytobesomeonewhowillsellfirewood.Likely,youcanlookinthephonebookorlocalnewspaperandfindsomeonesellingwood.Oneoftheattractiveaspectsofbuyingwoodisthatmanyentrepreneurstruly

runafull-servicefirewoodbusiness.Theywill(inparticularwithregular,returncustomers)askhowsmalltosplitthewood,askwhatlengthsofwoodaredesired,deliverit,andevenstackitinthelocationofyourchoice.Inareaswithalotofwoodandalotoffirewoodbusinesses,pricesfortheseservicescanbeveryattractiveandcompetitive.Consideringthat,atleastatthetimeofthiswriting,firewoodpricesstillaverage$150to$200percord(orless)inmostpartsoftheUnitedStates,evenmasonryheaterownersreceivingthesedeluxefullserviceswillstillbepayingafractionofthecostofmostfossilfueloptionsforheatingalivingspaceorhome.OursamplehomeinCleveland,forexample,wouldatthesepricesonlyneed$300to$400worthofoakfirewoodforawholeheatingseason.Thosewhoaregoingtobuyallthefirewoodtheyneedshould,indeed,seek

outsupplierswhowillprovidefirewoodcutproperlyfortheparticularmasonryheater(s)tobefiredwithit.Don’tbeshyaboutrequestingtheappropriatefuel.Thereislittlepointinpurchasingfirewoodthatyouneedtocutorsplitagainonceitisdelivered(unless,ofcourse,thereissubstantialsavingsindoingso).Thisis,again,oneofthebeautifulaspectsofwoodasfuel.Itcanbecustom-cuttowhateversizeisperfectforthefireboxoftheheaterbeingused.

Finally,therearesomepeoplewhofeelthatfirewoodisjustamessyfuelandthatisreasonenoughtonotuseamasonryheater.Acleanandeasilymanagedsolutionispurchasingmanufacturedfirewood.Somelumber,flooring,andothercompaniesnowusecollectedsawdustandcompressitunderheatandpressuretomakeblocksof“hardwood”fuelsuitableformasonryheaters.Thefuelisneatlypackagedandstackedonpalletsforstorageinagarageorbarn.Becauseitisdenselycompacted,ittakesless(involume)oftheseblockstodothesameheatingasregularcordwood.Somemanufacturersclaimthatonepallet(approximately4feetsquare)istheequivalentof1cordoffirewood.Thisoptionoffersafuelsolutionthatisorderly,clean,andfreefrommoisture,rot,andbugsforthosewhojustdon’twanttodealwithcordwood.YoucanfindsomesourcesforthistypeoffuelinappendixA.

FirewoodSpeciesforMasonryHeatersAllwood-burningfireplaces,stoves,andfurnacesrequirequalityfueltoprovidequalityheat.Oneofthegreatadvantagesofamasonryheateristhatitisn’taspickyasotherstoveswhenitcomestofuel.Iencouragetheuseofanywoodspeciesinmyheaters.Ontheotherhand,manystovemanufacturersandretailerswillbequicktoinformcustomersthattherearespecificspeciesofwoodthatwillgivethebestperformancefromawood-burningdevice.Becauseofthistrend,manypeoplenowbelievethatmoreheatisproducedfromwoodslikeoak,maple,andcherrythanfromanyothertypeofwood.Inparticular,itisbelievedthatsoftwoodslikepineandfirhaveverylittleheatvalue.It’struethatpine,fir,hemlock,andcedarsarenotthebestfuelsfora

conventionalwoodstove,butnotbecausetheyarepoorfuels.Infact,ameasuredpoundofdrypinewillhavevirtuallytheidenticalenergycontentasameasuredpoundofoak.Pine,larch,cedar,fir,hemlock,andallothersoftwoodsareonparwithanyhardwoodwhenitcomestoheatcontentonaper-poundbasis.Conventionalmetalwoodstovesandfireplaces,inordertosupplyconstantheat,needaconstantsupplyofwoodduringallhoursofeveryday.Softwoodslikepineburnquickly,soifafireneedstobeburningalldayanditisbeingfueledwithpine,you’llhavetoaddfuelmuchmorefrequentlythanyouwouldtoanappliancefueledwithlonger-burninghardwoodspecies.Softwoodsalsocontainalotofresinoussap.Conventionalstovesburnwood

inanoxygen-starvedenvironment,andthoseresinsoftendon’tcompletelyburn

undersuchconditions.Indeed,suchanenvironmentresultsinincompletecombustionofanywood.Resinoussoftwoodscontributegreatlytotheaccumulationofunburnedresidue(creosote)insideastoveandchimney.Toputitplainly,softwoodsdrawattentiontothedeficienciesofthewoodstoveitself.Anappliancethatburnswoodcorrectlycanburnanydrywoodwithoutcreatingacreosote-accumulationproblem.Masonryheatersburnwoodcorrectly.Correctlyburningwoodsimplymeans

thefiringprocessisgivenenoughairforcompletecombustion.Inaddition,themasonryheaterfireboxdesignfacilitateshightemperatures—theotherrequisiteofcompletecombustion.Masonryheatersburneverythingcombustibleinwood.Pitch,sap,andotheroilsinsoftwoodsarejustmorefuelforamasonryheater.Themasonryheaterdoesnotneedconstantstokingtoheatalivingspaceallday,soitdoesn’tmatterifpineorsomeotherwoodburnsquickly.Theheatstillaccumulatesintheheaterandislaterreleasedintothehome.

FIGURE10.6.Agoodruleofthumbforjudgingifapieceofsplitwoodisthepropersizeistoseeifa3-inch-diametercirclewillfitinsidethetriangularcrosssection.Ifalargercirclewouldfit,thatpiecemaybeworthsplittingoncemore.

Theappropriate,qualityfuelforamasonryheaterissimplyanydrycordwoodsplitto3or4inchesindiameter,orlimbsandbranchesoftherightlengthandsmallerthan3or4inchesindiameter.Whencontemplatingsplitwoodthatmighthaveatriangularcrosssection,thinkaboutwhethera3-inch-diametercirclewouldtouchthethreesidesofthattriangle.Ifitwouldn’t,youmayneedtosplitthepieceofwoodoncemore(seefigure10.6).MypersonalruleofthumbisthatifI’munsureifitissmallenough,Isplititagain.Thespeciesofwoodjustdoesnotmatter.Themoreimportantconsiderationforfirewoodisitsseasoning.

FirewoodSeasoning

Ifthereisonepartofthisbookthatmustbereadbyeverypersonwhoburnswood,itisthisone.Nearly100percentofallnewmasonryheaterownerswhothinktheirinvestmentmayhavebeenapooronehavetriedtooperatetheirhigh-performancemasonryheaterusinglow-octanefuel;inotherwords,theyusedwoodthatwasnotproperlyseasonedandcontainedalotofwater.Almostevery“problem”thatcustomershavewithamasonryheaterhaslittletodowiththedesignorconstructionoftheheaterandmostlyhastodowithnothavingseasonedwood.Thecomparisontogasolineisveryapropos.Ifthefueltankofacaraccumulatesevenarelativelysmallamountofwater,theenginewillsputter,hesitate,andperhapsnotevenrun.Inshort,thecarwillnotperformasdesigned.Thesamecanbesaidofamasonryheater.Waterdoesnotburn.Thisstatementissoridiculouslyobvious,yeteveryyear

tonsofwoodisfedtoallmannerofwood-burningdeviceswhenitisfreshlycut,ornearlyso.Usingwetwoodistheequivalentofburningwell-driedwoodbutsprayingwateronthefireatfrequentintervals.Itisdifficulttogetheatoutofawoodfireifitiscontinuouslydousedwithwater.Trees,likeallplants,containvastamountsofwater.Manyhaveheardthe

statementthathumanbeingsare95percentwater.Well,treesarethoughttobeabout50percentwater.Atharvest,freshlyfelledhardwoodsholdapproximately60percentoftheirdryweightinwater.Softwoodscancontainmorethan120percentoftheirdryweightinwater.Ihopethecasehasbeenmade:Woodcontainsalotofwaterthatwillnotburn.Tomakewoodsuitableforanywood-burningappliance,itmustbeseasoned.

Thewordseasonedderivesspecificallyfromtheideathatcutandsplitwoodmustdryovermanyseasonsbeforeitwillbesuitablefuel.Thequestionbecomes,“Howmanyseasonsandunderwhatconditions?”Or,moresimply,“Howisfirewooddried?”

WoodMoisture

Therearetwotypesofmoistureinwood.Thereis“free”moistureandthereischemicallyboundmoisture.Asthetermimplies,freemoistureissimplywaterwithinthevariouscapillariesofthewood.Likewaterspilledonthefloor,free

moistureinalogsimplyneedstoevaporate—mostconvenientlybymakingitswaybycapillaryactiontotheendsofthelogwhereitwillmeettheopenair,whichwhisksitaway.Chemicallyboundmoisture,ontheotherhand,ispartofthestructureofthe

wooditself.Thismoisture,againasthenameimplies,isboundtothemoleculesoftheotherconstituentsofthematerial.Thedryingprocessforwatersoenslavedismoretimeconsuming.Thewatermustfirst,ofcourse,beliberated—freed—sothatit,too,canmakethetripoutofthelogandintotheair.Avisitortothecountyjailcansimplywalkdownthehallandoutthedoorintothebrightsunshine.Aprisoner,boundtohiscellbybarsandacourtsentence,requiresmoretimeandadditionalmechanismsbeforehewillbeabletowalkoutthedoortofreedom.Inotherwords,ittakesmoreenergyandtimetoremovechemicallyboundmoisture.

WaterLiberationThetwomechanismsmostadvantageousfordryingwood—freeingallmoistureandlettingitevaporate—areairmovementandwarmtemperatures.Airmovementalonewillnotnecessarilydrywoodquickly,andneitherwillwarmtemperaturesalone.Forexample,wetwoodexposedtowindonafreezing-colddaywilldrymuchslowerthanthesamewoodexposedtowindonawarmday.Andwoodexposedtohottemperatureswhenthereislittleairmovementwillnotdryasfastaswoodexposedtohightemperaturesandwind.Bothwarmtemperaturesandgoodairmovementarenecessaryforrapidwooddrying.Thisshouldhelptoexplainwhyittakesmanyseasonsforwoodtodry.

Dependingonthegeographiclocation,everyseasonisdifferent,andonlyarelativelysmallfractionofagivencalendaryearofseasonsprovidestheidealconditionsfordryingwood.Somelocationswillhaveveryhumid,nearlywindlesssummers,whichslowthedryingtime.Others,especiallymorenorthernclimates,wheremasonryheatersaremuchmoreprevalent,haveveryshortsummersandlong,coldwinters.TherearenoplacesinNorthAmericawhereidealwood-dryingconditionspersistthroughouttheyear.Thisiswhyitisnecessarytohavemostwooddryforclosetotwoyears—eightseasons—beforeitwillbereadyasfuel.Thekeytogoodfirewoodseasoningisgoodcoverandgoodventilationovera

two-yearperiod.Outinthecountryyouwillsometimesseewoodstackedonthe

groundbetweentreesoutintheopen.Thismakesforgreatventilation,butnotgoodcover.Astackofwoodthatisnotcoveredontopwillcontinuetobewetandwillfrequentlygrowmosses,molds,andevenmushrooms.Rainandmeltingsnowpenetrateintothecenterofthestackandkeepitcontinuallymoist.Thisdoesnotproducegoodfuelforanyfireplace.Infact,storingwoodfortwoyearsundertheseconditionswilllikelyproducefirewoodthatisspongyandnearlyimpossibletoburn.

FIGURE10.7.Acombinationtile-and-stuccomasonryheateroccupiesonewholewallofthisroom.Organic,curvedshapesandmultiplelayersprovidemaximumsurfaceareaforheatradiation.Notethewoodstorageontheleftandplentifulseatingonthewoodenbench.PhotocourtesyofBiofire,Inc.

Likewise,somepeoplewillstorewoodinaclosedgarageorshed.Thisisexcellentcover,butpoorventilation.Thewoodisalwaysprotectedfromprecipitation,yetthereislittleopportunityfortheexcessmoisturetoescapetheconfinesoftheenclosure.Onceagaintheresultisoftenimproperlyseasonedfirewood.Woodstoredinaclosedshedorgaragewilltakemuchlongertodry.

Additionally,storinggreen(freshlycut)woodindoorscaninviteotherunattractiveproblems.Itistrulyincrediblehowmuchmoistureispresentinnewwood.Inanindoor,warmenvironment,likeanattachedheatedgarage,thehumiditylevelcanincreasedramaticallyinashortperiodoftime.Havingnowhereelsetogo(ifthebuildingisnotventilated),themoisturecancondenseonwalls,windows,cars,andanythingelsepresent.Thiscanleadtooxidationofmetalsandmoldandmildewgrowthonwood,drywall,andothersurfaces.Inshortordermanythingscanbethusruined.Tomakemattersworse,thehighmoistureenvironmentattractseverymannerofinsect;insectswillthriveinthewood,thewalls,andthroughoutthearea.Eventually,thesebugsarebroughtintothehomewiththefirewood.Thisishowtheideawasformedthatwoodburninginvolvesalotofmessandbugs;spongy,insect-infestedwoodisalwayswoodthathasnotbeenproperlystored.

ProperWoodStorageTherearemanywaysofstackingandstoringwood.Somearepermanentconstructionsandsomearebuiltfromthefirewooditself.Thereisno“right”firewood-seasoningvenueotherthanfollowingtherulesofallowingaircirculationandexposuretowarmthwhenpossible.Hereareseveralviablewaysofstoringsunbatteriesinabackyard.

TheLow-CostWay

Properwoodstoragecanbeverysimpleandwithoutexpense.Agoodstarterwood-storagemethodbeginswithobtainingsomegoodpalletsfromalocalbusinessthatmaybehappytohavethemhauledaway.Thesearesituatedone-after-the-otherinarowonthegroundasa“floor.”Sinceacordofwoodis4feetwideand8feetlongby4feethigh(4'×4'×8')andatypicalpalletiscloseto4feetsquare,everytwopalletscanrepresentacordofwoodifstacked4feethighwithfirewood.It’salsoagoodideatoputsomebricksorconcreteblocksunderthecornersandcenterofeachpallettoelevatebothpalletandwoodofftheground.Thisway,thepalletswillnotrotorsinkintotheearth.Thepalletsthemselves,owingtotheirmethodofconstruction,willpermitaircirculationunderneathallthewoodthatisstackedonthem,furtheraidingthedryingprocess.Thewoodisthenstackedcrisscross-orlog-cabin-style,leavingalittlespace

betweenthepieces(seefigure10.8).Presumably,ifyouhaveasinglecordofwood,you’llusejusttwopallets;for2cords,fourpalletsareused,andsoon.It’sgenerallyeasiesttoworkfromoneend,stackingroughlyathirdofapalletatatimesothatitisnevernecessarytoreachoveratallstackofwoodtofilloutapallet.Thelog-cabinstyleofstackingmakeseachstackonapalletstable,ifyoutakecarethatitisnotleaningsubstantiallyonewayoranother.Inthisway,noadditionalconstructionisnecessarytosecureandholdthewoodinplace.Asthelastofthewoodisplaced,youcanlookoverthewholestackandaddthelastamountofwoodstrategicallytomakesureallthestacksarethesameheight.

FIGURE10.8.Firewoodstackedinacrisscrossorlog-cabinstyle.Onerowisturnedperpendiculartothenext,makingastablestack.

Thosewhoaredetail-orientedmaywanttoattempttomakeonewholeedgeoftheresultingrectangularsolidofstackedwoodhigherthantheoppositeend.Thiswillaidindrainingwateroffthemassofwoodonceacoverhasbeenplaced.Simplecoversforwoodstackedinthismannercanbeplastictarpsoverplywoodoroldpiecesofcorrugatedmetalroofing.Anythingthatwillshedwatercanbeusedasa“roof”overthewood.Thepointistocovertheentiretopofthestacksofwoodbutleaveallthesidesopen.The4-foot-tallstacksofwoodwillgetwetonthesidesfromdrivingrains,butsuchwaterwillnotpenetratethestacksdeeplyenoughtobeaconcern.The“roof”canbeheldinplacewithbricksorotherheavymaterials,oritcanbestrappeddownwithropeorbungeecords.Otherwise,strongwindswillblowitoffthewoodpile.

TheHolzmiete

TheGermanwordholzmietetranslatesliterallyas“woodclamp.”AlthoughthewordclampinEnglishusuallymakesusthinkofadeviceforsqueezingtwothingsorsurfacestightlytogether,what“woodclamp”reallymeansinthiscaseisastructureforholdingwood.SotheGermanholzmieteissimplyawoodholder.Morespecifically,itisatraditionalwayofstoringalotofwoodinarelativelysmallspaceandinamannerinwhichitwillstilldryeffectivelyinatwo-yearperiod.Thestructureisessentiallyashortsiloofwoodasopposedtotherectangularblockdescribedintheprevioussection.Itcanbefunandchallengingtobuildandiseasiesttodowithseveralpeopleworkingonittogether.Thefirstconsiderationwhenbuildingaholzmieteisknowinghowmuchwood

youhave.Agood,stableholzmieteshouldbeatleast2to3yardsindiametertobestableandwellconstructed.Suchastructure,ifbuilt3yardstall,whichisnotuncommon,willholdcloseto4cordsofwood.Thusastructurelikethiswillholdalotofwoodinarelativelysmallarea.Throughoutthefollowinginstructions,plantocontinuouslysetasideina

separatepileanylargepiecesofbarkorpiecesoffirewoodwithbarkstilladhering.You’llusethemattheveryendoftheconstruction:Findaflat,well-drainedareathatwillaccommodatetheholzmietesize

desired.Beginbynailingastakeorpeginthecenterofthelocationandusingalengthofstringequaltotheradiusoftheholzmiete.Usethestringasaguidetomakearingofwoodtothatdesiredsize,layingwoodpiecesend-to-endallthewayaroundthecircle.Preferably,thisringoflogsismadewithpiecesofsmall-diameterwood,perhaps3inches.Thenyoucanremovethestringandstake,astheywillnolongerbeneeded.Next,placepiecesofwoodperpendiculartoandontopofthefirstringsothat

theycreateacircleoflogsleaninglengthwiseintowardthecenterofthecircle.(Inotherwords,amarblelaidonthehighsideofoneoftheselogsshouldrolldownthelogtowardthecenterofthecircle.)Onlyoneendofthesepiecesshouldbeontopoftheinitialring.Theotherendrestsontheground.(Notethatthisstructurecouldalsobebuiltonafoundationofpallets.)Fromhere,youbeginmerelyplacingmorewoodontopofthisleaningring.

Caremustbetakentofitpiecestogetherwellenoughthattheydonotbecomeunstable,yetremainlooseenoughthatthereissomeroomforaircirculation.Itwillnotbelongbeforeyou’llhavetofillinthespaceinsidethisbigcirclelest

piecesslideofftheirneighborsintothecenter.Thecenterareaisfilledbyplacinglogsverticallyagainstoneanotherand

againsttheouterringofwood.Thispartoftheconstructioniswherehelpismostneeded:Onepersonstandsinsidetheringplacingwood,whileoneormorestandoutsidefeedinginthewood.Somebuildersofholzmietearenotsofussyandjusttosswoodintothecenterareaandletitfallwhereitmay.Theconstructionmethodcontinuesuntiltheouterringisbuiltandtheinsides

arefilled.Asitbecomesclearthatthefirewoodsupplyforconstructionisdwindling,itistimetobegintransitioningtowardcompletion.Todothis,theconstructionoftheouterringceasesandwoodgetspiledupinthecentersothatitistallerthantheheightoftheoutside“wall.”Someeffortshouldbemadetomakeauniformslope,sothatitlooksliketheconicalroofofayurt.Theverytoplayersofthis“roof”willbemadewiththesavedpiecesofwood

withbarkstillattached,aswellaswithloosebarkbyitself,forminganaturalshakerooftoshedwaterfromtheconstruction.Startatthe“eave”oftheholzmiete,justaswhenroofingahouse.Barkandwoodareoverlappedbotharoundtheperimeterandeavetotheridge.Envisionthepathofastreamofwaterandattempttoassurethatsaidstreamwillalwaysmakeitfromtheridgeoftheconeallthewaytothe“eave”withoutpenetratingthecentermassoffirewood.Inthiswayawater-imperviousstructureiscompletedentirelywiththefirewooditself(seefigure10.9).

FIGURE10.9.Theholzmieteisacreativewaytostoreandseasonfirewood.Photocourtesyofwww.holzmiete.de.

Ofcourse,itisalsopossibletocoverthetopwithtarps,plywood,metalroofing,oranyotherwater-sheddingmaterial.Theoriginalandtraditionalmethodusesonlythebarkandbark-coveredwoodasprotection.Theideaistomaintainairspacethatwillallowmoisturetobewickedoutoftheholzmiete.Theoretically,theouterringofwoodwillnaturallygiveupitsmoisturetotheoutsideair.Theinnerwood,standingvertically,willpresumablyfosterverticalmovementofairthroughitsmass,helpingittodry.Tarpsorotherimpermeableroofswillinhibitthisaction,thoughmetalroofingorwoodenboardswouldstillallowsuchairmovement.Theresultingstructurelookslikeawoodenhutoryurtandhousesagreat

quantityofwoodinasmallspace.The“walls”oftenslopeslightlyintowardthecenterasaresultofthewayfirewoodwasslopedfromtheverybeginning.Somepeople,however,buildthewallsvertically.Forthosewithacoupleofyears’supplyofwood,severalsuchstructurescan

bebuiltonenexttotheother.Therehavebeenclaimsmadethattheholzmietewilldrywoodfasterthanmoreconventionalmethods—likestackingthewoodonpallets—butevenGermanswhousetheholzmietesaythatyoushouldstorewoodlikethisforabouttwoyearsbeforeusingit.

ThePermanentWoodshedForatotalfirewoodconnoisseur,considerafirewoodshedwithapermanent,wide,overhangingroof,andanelevated,ventilatedfloor.Wallscanbenonexistentormostlyopentoagainallowthedryingbreezestopass.Thistypeofsheltercanbewellworththeefforttobuildbecausethecoversoverlesspermanentwoodstoragecanbecomeanobstaclewhentheybecomesnow-coveredorwhenstrongwindsblow.Ifthestackofwooditselfiswhatsupportstheprotectiveweathercover,thenasfirewoodisused,thesupportfortheroofbecomesunevenorunstable.Theresultcanbesnow-coveredwoodatthetimeofyearwhendrywoodisneededmost.Investinginabuildingdevotedspecificallytofirewoodcreatesalifetimeofsimplifiedwoodstorage.Therearemanypossiblestructuresthatcanbeusedorconvertedtousefor

thispurpose.Asimplelargeshedwithafootprintofabout12feetby16feetandhavingan8-footceilingheightcanhouse8cordsofwoodandstillhaveawalkway/aircorridordownthemiddle.Bykeepingsoffitsandoverhangsuncovered,ormakingwallswithwoodenslatsratherthancompletesiding,good

aircirculationisachieved.Onceagain,palletsonthefloorpromoteaircirculationunderthestackedwood,promotingthebestdryingconditions.Someruralmasonryheaterownersuseretiredcorncribsandairybarnstostoreandseasontheirfirewood.OnesimpledesignpromotedbytheWashingtonStateUniversityDepartment

ofEcologyisshowninfigures10.11and10.12.Thissimplestructurecanbebuiltinaweekend,yetwillprovidemanyyearsofabundantprotectionforfirewood.Thebeststrategytouseinconjunctionwiththisdesignistomakesurethelargeopeningisfacingawayfromtheprevailingwinds,and,onceagain,usepalletsorsometreatedwoodenmembersonthefloortoelevatethewoodofftheground.

FIGURE10.10.Awell-built,roofedwoodshelter.Thisshelterhassolidsidesonallbutoneside,othersheltersuselatticeworksomorewoodisexposedtothedryingeffectsofthewind.

FIGURE10.11.Asimple,easy-to-buildwood-storageshelter.DesignbyWashingtonStateUniversityDepartmentofEcology.

FIGURE10.12.Notethatwoodissupportedoffthegroundtokeepitasdryaspossible.DesignbyWashingtonStateUniversityDepartmentofEcology.

SparksofInsight

Thereisnosubstituteforproperlydriedwoodforamasonryheater.Icannotstressenoughthatthisisthesinglemostimportantaspectofproperlyoperatingaheater.Thebestwaytomakesureplentyofdrywoodisavailableistobeginbysecuringatleastatwo-yearsupplyfromtheoutsetandplanningalwaystomaintainthatcushionofextrawood.Itiscommon,however,forownerstoencountertimeswhentheyrunoutofwoodforavarietyofreasons.Ifthemasonryheateristhesolesourceofheatforalivingspace,thisisahugedilemma.Somehow,qualitywoodmustbeobtainedinshortorder.Thismaybeharderthanitseems.Becautiousaboutsimplyopeningthephonebookorrespondingtoadstofind

“seasoned”firewood.Rememberthatthewordseasonedmeansthewoodhasbeencutandstoredfor,itishoped,morethanoneseason(say,summerandfall).Thewordseasonedinnowayassuresanyonethatthewoodhasbeenstoredproperlyundercoverformorethanayear.Tosomedealers,seasonedcanmeanthewoodwascutandthrowninapileforafewmonths.Thewoodattheinsidebaseofthatpilecanliterallybesittinginpuddlesofwaterforthedurationofthat“seasoning.”Thevendormaybeentirelyhonestinhisstatementsthatheisselling“seasoned”wood,basedonhisunderstandingoftheterm,butthatdoesnotguaranteethatthewoodisdryatall.Askatleastthefollowingquestions:

•Howlonghasthewoodbeenstored?

•Hasthewoodbeenstackedneatlyfordrying?

•Hasthewoodbeencoveredduringthewholeseasoningperiod?

•Howsmallhasthewoodbeensplit?

•Whatlengtharethewoodpieces?(Willtheyfitmyfirebox?)

Byaskingthesefivesimplequestions,youcandetermineimmediatelyhowwellpreparedthiswoodreallyis.Ifithasbeenstoredforlessthanayear,uncovered,inarandompileandmanylogshavebeensplitonlyinhalf,youcansafelyassumethewoodwon’tbereadyforuseinamasonryheaterforaslongastwoyears.Ifyouneedwoodimmediately,findanothersource.Thereisnomagicsolutiontothisquest.Finally,alasttipthatisgoodforallwoodburningisthatproperlyseasoned

woodwillbeatitsabsolutebestifyoubringitintoyourhomeatleastafewhoursbeforeyouactuallyburnit.Residualsurfacemoistureonthewood,fromhumidweatherconditions,willevaporateinthatperiodoftimewithinthedrierconfinesofthehome.Inaddition,thewoodwillbewarmedtoroomtemperature,thusjump-startingtheheatingprocessoftheactualfire.Noenergywillbeconsumedinthefireboxtowarmthewoodby,perhaps,70°F.Thislastdetailmakesgoodwoodsuperbandpromisesawarmmasonryheaterwithwhichtosnuggleonthoseterriblycoldwinternights.

THEJOHNHENRYOFMASONRYHEATERS

LindsayandKathyGrahamlive,asLindsayputsit,“inGod’scountry,”onanarrowfarmlaneinnorthwestOhio.Lindsay,ajack-of-all-trades,buildscustom

furnitureusinggreatslabsofwoodwithliveedgesorwithbook-matchedpairs.Healsoraisesgrass-fedbeefcattleandfree-rangechickenswhenhe’snothelpingpeoplewithalternativehealingtechniques.Kathyisaregisterednurseandrunsakidneydialysisunitatalocalmedicalcenter.Theirhomeisarecycledbarnwithallthebeamsandjoistsexposed,wideplankfloors,barnsidingforwalls,andstuccohereandthere.Rightnexttothestairway,closetothekitchen,sitsamassivelimestonemasonryheaterwithheatedbenchesonthefrontandoneside,abakingoven,andalargeglassdoubledoor.KathyandLindsayhavelivedwiththeirmasonryheaterforaboutsevenyears

now,buttheyarenotnewtoheatingwithwood.Priortoinstallingthemasonryheater,theirhomewasheatedwithawood-firedboiler.Lindsayremembersthatwhathedidlikeaboutthatboilerwasthatitwasn’tpickyaboutwoodsize;hecould“chuckjustaboutanypieceofatreeintothatthing.”Theyalsooccasionallyusedanantiquewood-firedcast-ironstove,thoughthatwasmainlyanoveltyitem.(ItdidsavetheirbehindsoneThanksgivingwhentheelectricrangediedandtheyneededawaytocooktheturkey!)Lindsaylikesthemasonryheater,though,becauseitprovideswhatnoother

heatingsystemdoes.“Itsbigadvantageisthatitisaconcentratedsourceofheat.It’saplacethatIcangoandsitagainstaftergoingoutinthecoldtodochores,”saysLindsay.Hefirstheardofmasonryheatersinthelate1980s,buthedidn’treallyunderstandwhattheydiduntilIdemonstratedtheoneinmyhouse.Hewasimpressedbythefactthatitwasgivingoffsomuchheatthoughithadnofireinit.Healsolikedthefactthatitwasan“electricity-proof”waytoheat.Whilehiswood-firedboilerneededelectricitytopumpwaterthroughthehouse,themasonryheateriscompletelyself-sufficientandoffthegrid.

FIGURE10.13.LindsayGrahamandhissonZachveneeredthisheaterwithlocallimestoneandsandstone.It’snowtheprimaryheatsourcefortheGrahamhousehold.Thisheaterisalsopicturedinfigure6.35.

Lindsaychucklesinawaythatmakesanyonelaugh,andhedoessowhenhedescribesthelaboriouswood-processingprocedurehewentthroughforthefirstfewyearsofmasonryheaterownership.“It’swhatyoumightcall‘recreationalwood-moving,’”hesayswithasmile.“I’dsplititandstackitintheyardundermetalroofing.Then,afterithadsatformonthslikethat,I’dmoveitagainintothepermanentlyroofedwoodshed.Then,ofcourse,fromthere,I’dmoveitathirdtimeintothehousetoburnit.Aguyhastobenuts!”Forallhiswork,hefoundthatthewoodwasstillnotdry,evenafterayearof

enduringhisprocess.Nowhesplitsitandstacksitonceoutsideundersheet-metalcoverings.Whatismakingtherealdifferenceindrying,hesays,isthathenolongerstacks4-foot-widepiles.Hemakesallhisstacksnarrowersothattheygetmaximumexposuretothedryingeffectsofwind.Inhisoldermethod,thewoodthatwasstuckinthemiddleofa4-foot-widestackjustneverdriedright.

“Anotherthing,”Lindsayadds.“Peoplethinkthosehydraulicwoodsplittersareatimesaver.Iknowforafactthattheyaren’t.Icansplitmywoodbyhandwithamaulmuchfasterthanthatmachinecan.Bythetimeyouwaitforthehydraulicsplittertoresetitsstrokefromonepass,I’vealreadysplitacouplemorepieces.”Heownedasplitterforseveralyearsandfoundthatstoringit,movingitaround,andusingitweremoreofaproblemthanitwasworth.Sohesoldit“for$50morethanIpaidforit,”helaughs.“Peopleneedtoknowthatamasonryheaterisacommitment,”Lindsayadds.

ThisJohnHenryofthetwenty-firstcenturyisnotdeterredbytheeffortrequired.Healreadyhaswoodsplitatleastayearinadvanceandworksonitalittleatatimeallthroughthecoolerseasons.Muchofthefuelcomesfrom3acresofhiswoodedland.HeandKathyappreciateknowingthattheyarenotdependentonanyoneforenergyandtheyalwayshaveawarmspotinthehousenomatterwhatitdoesoutside.

FIGURE11.1.Abrickheater,oven,andcookstovecombinationintheheartofthehome.Thecookerhasitsownmetalovenwhilethemasonryheaterhasablackoven.Inthisphotoflamesfromthefireinthemainfireboxcanbeseenintheoven.Noticethegraniteovenshelfandbacksplashontheheatersidetoprotectthebrickfromcooktopsplatters.PhotocourtesyofMaineWoodHeatCompany.

CHAPTERELEVEN

UsingaMasonryHeater,Bakeoven,andCookstove

Forpeoplewho’veneverlivedwithamasonryheaterbuthaveonlyheardgreatthingsaboutthem,thereisagreatdealofexcitementaboutthisparticularpartofanewhouseorroomaddition.Sometimestheheatermasonistreatedlikeaking(tothedismayofotherworkersonthesite)becauseheisbringingsomethingsounique,sorevolutionary,andsospecialintothemix.Heorshegetswinedanddined,treatedwithkidgloves,andspokentowithsomethingnearreverence.Thisdoesnothappenallthetime.Forsomehomeowners,however,themasonryheateristhecrownjewelofthehome,andtheycan’twaittoseeitbuilt.Onceitisbuilt,theanticipationhitsanall-timehigh.Thehomeownerwas

partofthedesignprocess.Maybethehouseplanswerealteredoradjustedtomakethemasonryheaterfillaspaceinjusttherightway.Maybesomeamenitiesoftheproposedhousewereeliminatedtoaccommodatethemasonryheater.Theownerhasheardaboutthepleasureofradiantheatbutnotyetexperienceditfully.Intruth,theconvolutedfluepathoftheheaterstillamazes,andmaybeevenconcernsthehomeowner.Willitactuallywork?Willthesmokeactuallymakeittothechimneyinsteadofcomingintothehouse?Whatwillthisheaterreallyfeellike?Isitreallyasgoodaswe’veheard?Manyanewmasonryheaterownerhassaid,“Ican’twaitforcoldweathersoIcanfinallyusethisthing!”

UsingaMasonryHeaterEventually,theweatherdoesturncolderandtheopportunitypresentsitself.Sohereitis,somethingthatisn’tquiteafireplaceandisn’tquiteawoodstove.Howintheworlddoesitwork?Howdoesthewoodgetloaded?Howdoyoustartthefire?Howdoyouknowhowmuchairitneeds?Thequestionscanbenumerousandeachoneanswered,liketheHydra’sdecapitation,spawnstwomoreinitsplace.Fortunately,amasonryheaterisquiteeasytouse.Homeownersquicklyfindthatamasonryheaterisreallythelazyman’swaytoheatwithwood.

TheBreak-InPeriod

Perhapsthemostcriticalpointinthelonglifeofamasonryheaterisitsinfancy.Likeanewbornbaby,itiswetbehindtheearsinthemostliteralway.Afreshlycompletedmasonryheatermayactuallycontaingallonsofwaterinallitsmass.Themasonmayhavesoakedfirebrickstoimprovemortarbondingasheproceeded.Claymortarsholdanimmenseamountofwater,andevencommonmortar,ifusedontheexterior,containsagreatdealofmoisture.Whenamasonryheaterisnew,itiswet.Allofthismoisturemustbecarefullydrivenoutofthemasonryheater.Wood

ignitesat572°F,morethantwicetheboilingpointofwater.Drywoodburninginthefireboxofamasonryheaterwillrapidlyescalateintemperature,reachingsixormoretimestheboilingpointofwater.Ifanysignificantamountofwaterremainsinthemassofthemasonrywhentemperaturesrapidlyclimb,itwillbeturnedtosteam.Watermolecules,whenheatedrapidly,startmovingviolentlyandtakeupmoreandmorespaceasthemoistureturnsfromliquidtogas.Needingmoreandmorespace,thehotwatermoleculeswillcreatespacewheretherewasnone.Inotherwords,moisturetrappedinmasonry,thenheatedtosteam,willcrackthemasonryaseasilyasIcanbreakatoothpick.Thesoundisasickeningpop,orperhapsathudthatremindsyouofhearing,inthedistance,thescreechoftires,thenaquickcrashwhentwocarshiteachother.Withoutevenseeingit,youknowthatdamagehasbeendone.

TWODAMPERS?

Oneproudnewownerfoundthathedidnothavedraftdespiteotherwiseperfectconditions.Whenitbecameobviousthatsomethinghadtobewrongwiththechimney,buthecouldseenothingbylookingintoitfromabove,hedecidedtolowerabrickdownthefluetoverifythatitwasclear.Itwasnot!Hediscoveredthatthemasonwhohadbuiltthechimneyhadleftthechimneydamperclosedduringhischimneywork.Apparentlyhewasalittlecarelesswithmortar,whichfelldowntheflueandlandedonthedamper.Thedamper—inthiscaseaguillotine-likeplateofsteel—operatedbysimplypushingitintocloseitacrosstheopeningorpullingitouttoopentheflue(seefigure7.12).Enoughmortaraccumulatedonthedamperandsplasheduponthefluetilesthatwhenitcured,itbecameathin“damper”ofmortar.Theowner

couldopenthemetaldamper,andthemortar“damper”stayedinplacejustaboveit.Fortunately,thiscapablehomeownerwasabletousethatbrick-on-a-ropeasabatteringramtoknockthemortaroutoftheflue.Afterthat,hehadgooddraft.

Thefirststeptodryingtheheaterissimplytoletitrest.Allopenings,doors,oraccessesshouldbeleftopen.Thisincludesloadingdoors,bakeovendoors,soot(cleanout)doorsorplugs,air-supplydampersorcontrols,chimneydampers,andashboxdoors.Ifitwouldhelptoexposetheinsideoftheheatertocirculatingair,itshouldbeopened.Notallmasonryheatershavealloftheitemslisted.Somewilljusthavealoadingdoor,airinlet,andafewcleanoutopenings.Thepointistoprovideeverymeansformoisturetopassivelywickoutofthemasonry.Preferably,thisrestingperiodlaststwoorthreeweeks.Ifitwasaprofessionalheatermasonwhoinstalledtheheater,youshouldcarefullyfollowwhateverinstructionsheorsheprovided,thoughit’shardtogowrongwiththegentleapproachoutlinedhere.Thisdesiccationperiodcanbeaugmentedbytheuseofsmallelectricheaters

orevenlights.Thetiny,1,500-wattelectricroomheatersworkwell,eitherthepassiveradianttypeorthekindwithblowers.High-intensityworklightsoreventhecommon“trouble”lightscanbepositionedshiningonorintofluesandfireboxes.Anylow-levelsourceofheatlikethiswilleffectivelyevaporatealotofmoisturefromtheheater,thoughbynomeansisthisarequirement.Aftertherestingperiodoftwotothreeweeks(orasperthebuilder’s

directions),thenextstepistobeginhavingsmallfiresintheheater.Itiseasytogetimpatientatthispoint.Afterall,theheaterlooksgood,anditlooksdry.Thetemptationcanbegreattofillthefireboxwithanarmloadoffirewoodandfinallygetdowntobusiness.Youmustsummonyourlastreservesofforbearance,however,becauseitonlytakesalittlebitofwatertodoawholelotofdamage.Avastamountofwaterhasbeendissipatedbytherestingperiodandelectricheaters,ifused.Chancesaregoodtoexcellent,however,thatsomepocketsofmoistureremain.Theywillbedrivenoutbytheseundersizedfires.

DraftCheckBeforeyoulightamatch,it’swisetoverifythatthereisactuallychimneydraftsuitabletocarrytheexhaustupthechimney.Thereisnojoyinlightingthefirstfireinamasonryheateronlytohaveitpuffsmokebackoutthedoor!Evenifthe

chimneyistall,it’sproperlyplacedcentrallyinthehouse,andalltheother“chimneyrules”arefollowed,theremaybeunexpectedconditions.Seethesidebarforanexampleofsuchasurprise.Initially,youcheckfordraftwithamatchorlighter.Openthechimney

damper(ifequipped)andtheair-supplyvent,air-supplydoor,orslides.Alitmatchorlighterflameheldclosetotheairinletshouldnoticeablygetpulledintoortowardtheheater.Thisiswhatyouwant;itmeansthereispositivedraft.Iftheflamedoesnotgetpulledtowardtheheater,thereisextremelyweakornonexistentdraft.If,instead,theflameispushedoutawayfromtheheater,thereisabackdraft,andsuccessfullystartingafirewillbealmostimpossible.FIGURE11.2.Dry-stackedstonecontrastswithverticallinesinaheaterfeaturingheatedseatingandabakeoven.HeaterdesignedandbuiltbyStovemaster;photocourtesyofAlexChernov.

FIGURE11.3.Noticehowtheflameofthecandleispulledhorizontallyintotheheater—asuresignofgoodpositivedraft.It’swisetodothistestbeforelightingalargeloadofwood.

Inthefirstofthesepossibilities,draftexists,anditisdefinitelyokaytoproceedwithafire.Inthesecondcase,thereapparentlyisnodraft,butthereisgoodlikelihoodthatdraftcanbeestablished.Theheater(andprobablythechimney,too)is,afterall,stillcoldandwetinside—conditionsnotconducivetoencouragingstackeffect.Inheatersequippedwithagasslotorabypassdamper,it’slikelythatdraftwillbeeasilyestablished.Abypassdamperisamechanicalcontrolthatcircumventsthelongfluepathofthemasonryheateranddirectsexhaustimmediatelytothechimney.Agoodwaytoproceedistoburnfiveorsixcrumpledpiecesofnewspaperinthefireboxwithchimneyandbypassdampers(ifsoequipped)andairintakesopen,andthefuel-loadingdoorclosed.Thepapershouldburnbrisklywithtallflames.Afterthisburn,performthematchflametestimmediately;itshouldnowshowtherequisitedraft.Repeatifnecessaryuntilitisclearthereischimneydraft.Inheaterswithoutagasslotorbypass,onestrategyistoremovethesoot

cleanoutplugordooratthebaseofthechimneyandburnthecrumplednewspaperthere.Again,ifthechimneyisequippedwithadamperofsomekind,itmustbeintheopenposition.Alternatively,youcanuseahairdryertoprimethechimneyinlieuofthenewspapers.Somehomeownersuseapropanetorchforthispurpose.Repeatthisprocedureasnecessarytoassurethereisdraft.Alwayscheckusingthesimpleflametestratherthanassumingdraftisestablished.Iftheinitialflametestshowedtheflamebeingpushedawayfromtheheater,

thereisasignificantdowndraftcondition.Exceptunderverypeculiarweatherconditions(someofthesemightincludeanoutdoortemperaturethat’squite

closetotheindoortemperature,rain,orhighhumidity),thisonlyhappensifthe“chimneyrules”weren’tallfollowed.Dependingonhowseverethebackdraftreallyis,youmaystillbeabletoreverseit—especiallyifthereversalisminimal.First,checkthatnobathroomorkitchenexhaustfansarerunning.Itisagoodideatothentryaheater,blowdryer,orhotlighttowarmthechimneyorfireboxandestablishadraft.Lightingevenatinyfireofnewspaperswhenthereisreverseddraftisjustaskingforsmokeinthehouse.Iftheinitialflametestdrovethelittleflamestronglyhorizontallyawayfrom

theheater—particularlyifitdidsoinharmonywithastrongwindoutside—youhavevirtuallynohopeofestablishingdraft.Thisislikelyaharbingeroffuturedraftproblemsaswell,andagain,it’salmostalwaysrelatedtohavingachimneythatisshorterthanthetallestheatedpartofthehouseorachimneythatisentirelyormostlyoutsidethehouse.Itispossiblethebackdraftiscausedbyvariousexhaustdevicesinthehouseifanumberofthemarerunningduringthistest,soit’salwaysworthcheckingthosebeforethrowinginthetowel.Barringthat,ifabackdraftisquitestrong,it’sagoodideatoconsultaprofessionalheatermasonorchimneyspecialistatonce.

SmallBreak-InFires

Onceyou’recertainthatthemasonryheaterhasadequatedraft,it’stimetoproceedwithsmallbreak-infires.Asmallfiremainlyconsistsofseveralcrumpledpiecesofnewspapercombinedwithkindlingandsmallpiecesofwood(1to3inchesindiameter)totalingapproximatelyone-tenth(byweight)ofthefullloadrecommendedbythebuilderormanufacturer.Forexample,ifthedesignerofthemasonryheatersaysafullloadis35poundsofwood,thenusenomorethanabout3to4poundsoftotalkindlinganddrywood.Itwillbebesttousejustkindlingforthesesmallfiressincethedurationoftheburnwillbequiteshortandtemperaturesmaynotrisehighenoughtocompletelyconsumeanythingapproachingthesizeofregularcordwood.And,yes,thefactthatthesemeasurementsaregiveninpoundsdoesmeanthatyoushouldweighthewoodonascale—atleastuntilyoucanaccuratelyestimatewithoutone.

FIGURE11.4.Handmadetilesandstuccocoverthemassandfireboxelementsofthisheater.Plentyofwoodstorageisprovidedunderboththefireboxandtheunheatedbench.Designed,built,andphotographedbyErnstKiesling,CanadianKachelofen.

Agoodruleofthumbistoplanonhavingabouttensmallfiresbeforefullyloadingtheheater.Eachsubsequentsmallfireisslightlylargerthantheonethatprecededit.Plantoincreasetheweightofwoodusedbyabout5andnomorethan10percent(ofthefullloadweight)eachtime.Forexample,theheaterthattakes35poundsofwoodwilluseabout3poundsofwoodthefirsttime,about5poundsthenexttime,7thenext,andsoon.Bythetenthfire,thetotalweightwillbeasignificantpercentageofthemaximumsuggestedloadofwood.Asthefiresgrowinquantityofwood(byweight)andduration,thesizeofthepiecesusedcanbeincreasedaswell.Onceyou’reusingmorethan10poundsofwood,itisreasonabletoincludemoreregularcordwoodandlesskindlingandscraps.Animportantpartofthisslowbreak-inperiodistoleavetheair-supplyinlet

(andthechimneydamper,ifsoequipped)opencontinuouslyevenafterthefireisout.Theideaistoslowlywarmthemassandmakeuseofcontinuousdraft

conditionstocarrymoistureoutofthesystem.Ifyouclosedtheheateraftereveryoneofthesefires,themoistureliberatedbywarmthwouldremainintheheater,defeatingthepurposeofthisprocess.Anopenairsupplyandopenchimneyensuresthatexcessmoistureiscarriedupandoutofthesystem.Also,thesesmallfiresshouldhavearestingtimeofatleasteighthours;

preferablythereshouldbetwelvehoursbetweenthem.Firesspacedtooclosetoeachotherintimewillresultinheatingthemasstooquickly.Providinghalfadayofrestbetweenfiresallowstheheatofthefireandthecontinuousdrafttoslowlywarmeverypartoftheinnerlifeoftheheater.Thistimingtendstoworkwellwithmostpeople’sschedulesanyway.Lightasmallfireinthemorningbeforeyougoofftoworkandanotherintheeveningafterwork.Finally,itiswisetobrieflylookovertheheater’sexteriorandfireboxpriorto

eachlittlefire.Ifthereisevidenceofalotofmoistureorcondensationatanytime—especiallyinsidetheheater—itisbesttomissafireandlettheheaterrestanothereightormorehours.Thisisagoodopportunitytosubstitutethegentleheatofanelectricheaterorlamptoevaporatethatexcesswater,yetstillintroducesomeheatintotheprocess.Whenwaterisvisible,thereisnoreasontoriskturningwatertosteamandforfeitingalltheprogresstothatpoint.Likethetortoiseracingthehare,slowandsteadywinstherace.Newownersmayopentheirloadingdoortolookinsideandseeawhite,

crystalline“growth”onthesurfaceofthefirebox.Sometakeonelookatthisfuzzywhitestuffandthinkthereismoldgrowingonthefirebricks.Indeed,itdoeslook,atfirstglance,likewhitemold,butitismorelikeapowderthanalivinggrowth.Thereisnoneedforalarm:thewhitematerialissimplyefflorescence.Thisisadepositofmineralsonthesurfaceofthebricksthatoccursastheyandthecementdry.Ithappensasthewater,ladenwithsalts,wickstothesurfaceanddries;themineralsaltsareleftonthesurfaceofthebricks.Figure11.5isaclose-upofcrystallinemineralbuilduponmasonry.Ifthemasonsoakedthefirebricksinwaterbeforesettingthem,theremayhavebeensaltsinthesoakwaterthatthenappearlaterasefflorescence.Othermineralsmayhavebeeninthemortarorclaythatwasused.Theappearanceoftheefflorescenceisinnowayasignofpoorinstallationorthatpropermortarbondingdidnotoccur.Itissimplyabenigndepositofmineralsalts.Noactionneedstobetaken,thoughtheefflorescencecansimplybewipedaway.

FIGURE11.5.Itmaylooklikemold,butit’sjustastructureofminerals,calledefflorescence,“growing”onthebricksastheydry.PhotocourtesyofCharlesBuellInspections,Inc.

Otherwise,bythetimeyou’velityourtenthfireandareusingagoodpercentageofthemaximumloadofwood,youwillinalllikelihoodfeelsomeheatontheexteriorsurfaceoftheheater.Thismaybebarelyperceptibleonsomeheaters;othersmightbenoticeablywarm.Aneasycheckistoplaceahandpalm-downonatableorotherfurnitureneartheheater,thenimmediatelymovethesamepalmtothemasonryheater.Ifyoucandetectmorewarmthontheheater,it’sgettingwarm.Ifit’snot,makeafewmoreincrementallylargerfires.Whenyou’veusedthesmallbreak-infiresreligiouslyandyoufeelsomewarmth,it’stimetomoveontoafull-scalefire.

UNDERFIRE/OVERFIREAIR?

Underfireairandoverfireairrefertothewaycombustionairisfedtothefireofamasonryheaterinthefirebox.Underfireaircomesintotheburningfuelfromunderneath,usuallythroughagrateinthefloorofthefirebox.Overfireairfeedsthefirefromsomewhereabovethecoalbedofthefire(abovethefireboxfloor).Overfireaircantakemanyforms.Inmanycases,theairis

broughtintothefireboxalongthefront(thesidewiththedoor)andmayevenwashoverthedoorglassbeforebeingpulledintothecombustionprocess.Othersystemswillhavenumerousoutletsalongallthewallsofthefireboxtoprovideairfromvirtuallyeverypartofthewall(seefigure11.6).Theideaisalwaystosendjustenoughairtothecombustionprocess,andtodosoinsuchawaythateverypartofthefiregetsitsshareofoxygen.Repeatedinvestigationshaveshownthatoverfireairsuppliesreliablyresult

incleaner,morecompletecombustionthanunderfireair.

FIGURE11.6.Agoodexampleofafireboxwithprovisionforairsuppliedtothefireatalllevels.WhatlooklikecolumnsoftheletterAareholeseverycoupleofinchesuptheheightofthefireboxwalls.Also,thecorrugatednatureofthewallmeansthatfuelfallingagainstitwillnotrestricttheairsupply.ProjectbyNewEnglandHearthandSoapstone.

ARealFireatLastWhenamasonryheaterhasbeengentlywarmeddayafterdayuntilit’sfinallywarm,itisalsodry.Aproperlydesignedandconstructedmasonryheaterissupposedtoevenlywarmtheverticalsurfacesoftheheater.Ifthesesurfacesareonlymildlywarm,theinteriorismuchwarmer.Justasthehumanbodyhasacoretemperatureof98.6°Fwhileouterskintemperaturesare10°to15°cooler,themasonryheaterwillalwaysbewarmerinsidethanout.Iftheoutsideoftheheaterhasgottendryenoughtofeelwarm,theinnerlifehaslikewisedriedsufficiently.Atlast,itistimeforarealfire.Bythetimeyoureachthisstage,you’requiteaccustomedtotheprocedurefor

operatingtheheater.Airsupply,dampers,doors,andsoonhavebeenusedrepeatedly.Kindlingorfirestartersandfirewoodhavebeenweighed,placed,andlit.Theprocedureforafull-sizedfireisreallynodifferentthanwithallthebreak-infiresexceptthatnowthequantityofactualcordwoodisatitsmaximum.

Therearesomepeoplewholiterallyhavenoexperiencewithbuildingfires.Whatmustbeemphasizedwithamasonryheateristhat,inordertoachievehighcombustiontemperatures,theremustbesomespacebetweenpiecesofwood.Theideaistomakesureeachburningpieceoffirewoodcangetenoughairforvigorousburning.Thosewithlittleexperiencemaybeinclinedtosimplyplacepiecesofwoodrandomlyoneatopthenextandsidebysidewithnoairspaceatall.Youcangetawaywiththiswithareallyhotheater,butitisn’tagoodideaforonethat’sbarelywarm.Thefirststepbeforeanyfireislaidistoverifythatthechimneydamper(if

equipped)isopen,asisanyairsupply.Notethatsomecontraflowheaterdesignsinparticularmayhavetwodifferentair-supplylocations.Iftheheaterisequippedwithametalgrateinthefireboxfloor,thereisagoodchanceitwasdesignedtohaveanairintakebelowthelevelofthefireboxprovidingairthattravelsthroughthegrateandunderthefire.Thisiscalledunderfireair.Thesameheatermayhaveairintakeataboutthelevelofthefireboxfloorthroughairslidesinthedooritself.

FIGURE11.7.Afirewoodloadbuiltinthe“crib”style.Noticethatpaperisontopforstartinga“top-down”fire.

Mostotherheaterswillhaveonlyoneairintake.Thismaybelocatedatfireboxlevel,butitactuallyfeedsairtothefireatorslightlyabovefirebox-floorlevel—thoughsomeadvanceddesignsfeedtheairtothefirethroughpassagesinthefireboxwalls.Combustionairsuppliedtothefireatorabovefireboxleveliscalledoverfireair.Again,overfireairintakemaybethroughslidesoranopeningatthebottomoftheloadingdoor,orpossiblythroughacomputer-controlledventdesignedtopreciselygaugethecorrectamountofairthefireneedsthroughouttheburn.Unlessthebuilder,designer,ormanufacturer

specifiedotherwise,simplyopeningtheair-ventslidesshouldbeallthatisnecessary.Oncethesesettingsaremade,itistimetoloadthefuel.

TheBasicCribFireAswithbreak-infires,youshoulduseascaletoweighthequantityofwoodtobeplacedinthemasonryheater.Theeasiestwaytodothisistoweighyourselfonabathroomscalewithoutandwithanarmloadofwood.Thedifferencebetweenthetwoweightsistheweightofthefirewood.Itiswisetomakenoteofhowmanypiecesofcordwoodyouneedtohavetherightamountofwood.Forexample,ifthemasonryheaterrequires35poundsofwoodandtenpiecesofwoodweigh35pounds,youcansimplygathertenpiecesofwoodeverytimeafullloadistobeburned(assumingthat,overall,thefirewoodisuniformlysplit).Usingthescaleseveraltimesatfirstisagoodideatoverifythatthefirewoodis,indeed,uniform.Themostbasicwaytostartaneffective,hotfireinamasonryheateristo

crumplehalfadozensheetsofnewspaperonthefloorofthefirebox.Onthepaper,placeverydrykindlingwood—piecesnolargerthanyourlittlefinger.Avoidscrimpingonthekindling.Halfadozenpiecesofkindlingmaynotbeenough.Usekindlingsuchthatyoucan’tquiteholdallthepiecesinonehand.Afewmorethanthatcan’thurt,either.Thisisallfuelthatwillheatthelivingspace!Oneofthebigreasonspeoplegrowtodislikewoodburningistheideathatitishardtostartfires.Usingplentyofgood,drykindlingtogetherwithgood,drycordwoodmakesitverysimple.It’salsookaytoforgothenewspaperandkindlinginfavorofmanufacturedfirestarters.Ontopofthekindling—orjustinfrontofthekindling—closetotheloading

door,placeasinglepieceofcordwoodparalleltothefrontoftheheater.Thenplacearowofcordwoodpiecessidebysideperpendiculartoandontopofthesinglepieceinthefront.Thereshouldbesomespace—just½inchisfine—betweenpieces.Ontopofthatrow,setanotherrowperpendiculartothefirstwithsimilarspacing.Continuethismethodrowbyrowuntilyou’veloadedtheentirequantityoffuel.Thiswayofloadingwoodcanbecalled“cribstyle,”andisshowninfigure11.7.Withthewoodloaded,it’softenagoodideatocheckonemoretimethatair

supplyandchimneydamper(ifequipped)arereadyforoperation.Onceeverythingisappropriatelyset,lightamatchandignitenewspaperorfirestarter.

Shutthedoorandstartenjoyingabrisk,wonderfulfire.

TheTop-DownCrib

Theconstructionofa“top-down”cribisprimarilythesameasthebasiccrib.Thepaperandkindling(orfirestarter)arenotplacedatthebaseofthecrib;theywillbegoingnearthetop.Insteadofstartingwithasinglepieceofcordwoodparalleltothefrontofthefirebox,layacompletefirstrowofwoodatthebaseandthenfollowthesameconstructionmethodasthebasiccribuntilyou’veloadedalltheprimarywood.Then,ontopofthelastrowoffirewood,insertthekindlingandpaperatopthecribyou’vesofarconstructed.Inthiscase,larger,finger-sizedpiecesofkindlinggoontopofthemainfuelload,followedbysmallkindlingpieces,thennewspaper(and,perhaps,alittlemorekindling).Itisvitalinthistypeoffirebuildingtouseplentyofkindling.Otherwiseyou

maymeetwithaggravationwhenthekindlingisconsumedbutdoesnotignitethemainfirewoodload,andyouhavetorepeattheprocess.Mostpeople,again,arenotinterestedinwoodburningwhenitbecomesdifficulttostartfires.Withgood,dryfirewood,thisshouldnothappen,butitcan.Forthisreasonit’salsoperfectlyacceptabletoputsomecordwoodabovethekindlingload—particularlysomesmaller,verydrypieces.Thereasonthatthistop-downmethodisusefulandbeneficialisthatitalters

thephysicsofthefireitselfasitprogressesfromignitiontoconflagration.Inthebasiccribfire,theinitialfireprogressesrelativelyrapidlythroughtheentireloadofwood.However,thebeginningofthisprocesscreatesmoresmokeasalltheunburnedwoodrobsheatfromthefledglingfire.Temperatureshaven’tyetrisenenoughforcleancombustion,sothatsmokecontainswastefuelthatdepartsthesystem.Inotherwords,itisnotuntilallthewoodisinflamesthatcombustiontemperaturerisesquicklytoacleanburninglevel.Asthetop-downfireburns,itsnot-yet-fully-consumedcoalsarethestarterfor

thewoodbelow.Whenthatlowerwoodbeginsburning,itsintensecombustionwillfullyconsumethosecoals,whichinabottom-upfiremaynothappenquiteaswell.Also,asthewoodinthelowerpartofthecribgetsheatedtonearignitionandbeginsreleasingvolatilegases(thesmokecontainsalotofunburnedhydrocarbons),thatsmokeisforcedtoriseupthroughthealready-superheatedflamesaboveit,wherethosegasescanbeconsumedratherthanleavethesystemunburnedassmoke.Inthisway,thetop-downfireburnscleanerasitmethodicallymovesdownthestackofwood,ignitingonelayeratatime—thesmokegeneratedbeingdevouredbythehotcombustionaboveitand

coalsbeingcompletelyconsumedaswell.Ifthebuilderormanufacturerofthemasonryheaterhasgivenspecific

instructionastohowtofiretheappliance,andthoseinstructionsdonotincludeatop-downwayofburning,itisworthfindingoutwhy.Theremaybegoodreason;perhapsthespecificwaytheheaterisdesignedtogetairtothefiremakesthetop-downapproachunnecessaryorirrelevant.Otherwise,itisagoodapproachtofiringamasonryheateroranyotherwood-burningfireplaceorstove.

TheTepeeFireAnotherwayofbuildinganeffectivefireiswhatisknownasthetepeefire.Asthenameimplies,thefirewoodissimplystoodonendinthefireboxinthemanneroftheframeworkoftheNativeAmericanmobilehome.Typically,youleanthefirstfewpiecesofwoodagainstthebackorsidewallofthefirebox.Addpiecesleaningagainstthefirstfew.Leaveaspace,likeatepeedoor,atthebaseofthestructure.Inthis“door”youinsertthepaperandkindlingorthefirestarter.(Alternatively,youcanplacethepaperandkindlingfirstandbuildthetepeearoundthem.)Thetepeefireisanotherclean-burningmethodthatproducesrelativelylittle

smoke.Itdevelopsheatfastasalltheflamesfunneltogethertowardthetopoftheconstruction,producingagooddealofheatandburningtheingredientsofthesmoke.Somewillfinditmoredifficulttousetherecommendedfullchargeofwoodinatepeestylesince,tocreatestability,thecordwoodpiecestendtohavemorespacebetweenthematthebase,wheretheysitonthefireboxfloor.Someownershavefoundthequickdevelopmentofheatfromthetepeefireisanaidtoestablishingstrongdraftunderpoorpressureconditions.

EnjoyingaFire

Noinstructionsarenecessaryforenjoyingafire.Thisisoneofthemostpleasantaspectsofoperatingamasonryheater.Oncethefireisgoing,theloadingdoorisclosedandthefireviewingbegins.There’snoneedtopokeorprodthefire,addmorewood,changedraftsettings(formostheaters),orinanyotherwaytinkerwiththefire.Oneofthegreatestthingsaboutmasonryheatersisthatthefireis

easytostartand,onceitisgoing,itjustgoesandgoesandgoes.Anexperiencedownercangotothewoodshedforfuel,bringitinthehouse,

loadthewood,andstartthefireinamatterofabouttenminutes.Ifthewoodisalreadyinthehouse,thetimecanbelessthanfiveminutes.Thatfive-minuteinvestmentwillgenerallyrewardyouwithtwelveorperhapstwenty-fourhoursofwarmthfromtheheateralongwithabouttwohoursoffire-viewingenjoyment.Themostdifficultpartofthetaskispullingthecorkonabottleofwineorpoppingthecaponabeer—maybebrewingacupofteaorcoffee.Itisagoodideatoatleastcheckonthefireoccasionally,justincasesomethingunusualdoeshappen.Sincemostpeoplewanttowatchthefireanyway,thisisnobigcommitment.Thefireofamasonryheaterisdifferentfrommostfiresyou’veseenina

fireplaceorwoodstove.Mostmetalwoodstovesaredesignedtooperatewiththefireseverelydamped.Thismeansthefireprimarilyburnswiththeoxygenpresentinthewooditselfplusasmallamountfromoutsidethefirebox.Theresultisalazy,slowlymovingfire.Ontheotherhand,openfireplaces(withnodoorsorsimple,ungasketedglassdoors)burnwithsomuchexcessoxygenthattheyaremuchcoolerthanafireinamasonryheater.Themasonryheaterfireismorerobustandpowerful.Somehomeowners,upontheirfirstexperiencewithsuchalarge,vigorous

fire,areactuallyfrightened!Itisaremarkablesighttosee40poundsofdrywoodallblazingvigorously.Theflameswillbebrightyellow—perhapsevenwhiteasthefireburnsatitsmaximumefficiencyandtemperature.Newusersmayneedtochecktheairanddamper(ifequipped)settingstomakesurethefireisburningoptimally.Thefireshouldalwaysbevigorous,butcertainlynotoutofcontrol.Anout-of-controlvigorousfiremayhavevariouscharacteristics:Itmaypuffloudlylikealocomotiveengine,oritmayswirlinanuncontrolledfashioninthefirebox—firstcomingtowardthedoorglass,thenmovingaway.Thelarge,energeticflamesshouldmoveuniformlyinthedirectionoftheexit

fromthefirebox,whichmayeitherbeup,tooneside,ortotheback.Ideally,itisalongcolumnofflameratherthanaseeminglydisorganizedburn.Ifit’shuffingandpuffingordoingotherstrangethings,itcouldbethatitisactuallygettingtoomuchairtooquickly—ormaybenotenoughair,dependingonthedesignoftheheater.Sometimesthiscanbecausedbywindconditionsoutsidethehouse.Experimentwithcarefullyadjustingtheairsupplyand/orthechimneydampersettingtoseeifyoucanbringthefireintoamorecontrolledburn.Inthose

heatersthatsupplybothunderfireandoverfireair,oneortheothermayneedmoreadjustment.Thefireshouldneverbeseverelydampenedsuchthattheflamesadopttheslow-moving,lazylookthattypifiesametalwoodstovefire.Suchaburnisinefficient;itwasteswoodandproduceslessheatforstorageinthemassoftheheater.Notethatheaterscarefullydesignedaccordingtogeographiclocation,

chimneyheightandsize,andheatoutputrarelyexperiencethesetemperamentalconditionsbecausetheywerecustom-madeforthehouse.Withflues,fireboxsize,airsupply,andmassallspecificallydesignedforaparticularproject,itisraretoencounteranuncontrolledburn—though,again,strangeweatherconditionscouldcreateone.Usuallyitispremanufacturedheatersorheatercoresthatproduceunexpectedresultsduringchangingenvironmentalconditions—thesefireswillneedmorehumanintervention.Thefactthatthefiremay,indeed,roarisnotnecessarilyasignthatitisoutof

control.Ahotfireneedsadequateairand,again,40ormorepoundsofwoodblazingallatoncewillproduceadefinitelyaudibleroarorhumalongwiththemorefamiliarcracklesandpops.Ontheotherhand,withheatersthatareequippedwithachimneybarelymeetingthechimneyrules,thegreatroarmaybemuchmoresubdued.Itshouldstillburnvigorously,buttheflamesmaynotbequitesolong.Likewise,custom-calculatedheaterswillburnvigorously,butusuallynotasbrisklyasothers.FIGURE11.8.Afireinamasonryheaterismuchmorevigorousthanthatinanopenfireplaceormetalwoodstove.Thisheaterisalsofeaturedattheopeningofpart4andinfigure5.3.

Insummary,thefireshouldbestrongandbright.Ifatanytimethereisaquestionaboutwhetheritisreallyburningcorrectly,thebuilderormanufactureroftheheatershouldbewillingtoconsultand,ifpossible,makeanon-sitecallto

helpassessperformance.Mostownersquicklygrowaccustomedtotheenergyofthefireandsimplybecomeentrancedwhilewatchingtheflames.Yougetusedtotheair-controlsettingsforagivenamountoffuelandwillautomaticallysetthemintheappropriaterange.Suchisthestateofbeingincontrolofyourownheating.Youquicklylearnnewskillsthatbeforelongbecomesecondnature.

TheShutdownProcedureEventually,ofcourse,thefireburnstothepointatwhichtherearenoflames.Giventhelargeamountoffuelconsumed,thereisarelativelylargeaccumulationofred-hotcoalsonthefireboxfloor.Dependingonthetypeofmasonryheater,theshutdownproceduremayvary.Formanyheaters,itiscustomaryatthisstagetodotheonly“poking”thatiseverdoneinamasonryheater.(Andsomeheatersmaynotrequireeventhisintervention.Consultwiththebuilderormanufacturerifyouhaveanydoubt.)Atthispoint,theairsupplyforunderfireairshouldbetemporarilyclosed.In

fact,anyairsupplycanbeclosed.Thentheloadingdoorshouldbecarefullyopenedjustacrackandheldthereforacountoften.Thisactionpermitsthefiretoadjusttogettingairfromthedoorratherthanfrombelow.Ifthereisstillaircomingthroughagratebelowthefire,andthedoorisopenedquickly,thatactioncandrawexhaustgasesoutofthedoorintotheroom.Closingthatairsupplyandopeningthedoorcarefullyassuresthattheremainingcoalswanttodrawairinthroughthedoorinstead.Theten-secondcountisusuallyadequate,afterwhichthedoorcanbeopened.Withthedooropen,thecoalscanberakedintoaconsolidatedpilethatwill

encouragetheirrapidfinalcombustion.(Certainlytheycouldbelefttodiewithoutsuchstirring.Openingthedoortostirthecoalsintroducesroom-temperatureairenmassetothefireboxandwholesystemofflues,whichmaybecounterproductive.Consultthedesignerorbuilderofyourheaterforrecommendationsinthisregard.)Thepointofrakingthecoalstogetheristhateachcoalcontributesheattotheothersandthelastremnantsarecompletelyconsumedmorequickly.Youcanalsousetherakeorpokertobreaklargercoalsdowntothesizeofmostotherssothat,again,allofthemwilluniformlybediminishedinthislaststageoftheburn.Whenthisrakingisdone,closetheloadingdoorandopentheunderfireair(if

equipped).Ifthemasonryheaterhasnounderfireair,thenyoushouldopen

whateverprincipalairsupplyitdoeshave.Inthoseheatersthathavebothunderfireandoverfireairintakes,onlytheunderfireairshouldbeopenatthisstageasitdirectsairpointedlythroughthecoalbed.Theideahereistoquicklyconsumethecoals,drawingeverylastounceofheatenergyoutoftheremainingcoalsforstorageinthemass.Theactionofrakingthecoalstogether,closingthedoor,andopeningtheairsupplyusuallyresultsinthecoalsburstingonceagainintoashort-livedbutrobustfire.Thistime,insteadofbrightyellowflames,you’relikelytoseepaleblueflamesthatlastonlyforafewminutes.Theblueisthecombustionofcarbonmonoxide—producedfromtheincompletecombustionthatoccursasthefiretemperaturedecreases.Thecoalsafterthispointwillbegreatlyreducedinsizeandonceagainwillturndeepred.Oncethereisnomoresignofflame,youcanclosetheheater’schimney

damper(ifequipped).Mostofthedangerouscarbonmonoxidehasnowbeenconsumedordissipated.Additionally,mostdampersformasonryheatersonlyhave95percentclosuresothatifthereareanyremaininggases,theycanstillescapeupthechimney.Awhilelater,thecoalswillturnmainlyblackandthefinalairsuppliescanbeclosed.Thefireisfinished.Forthoseheaterswithoutdampers,butequippedwithtight-fitting,gasketed

doors,thisentireprocessisusuallydifferent:youmerelywaituntiltherearenomoreflames;atthispointyoucanclosetheairsupply.Therewillbenomoreflamesandnodraftupthechimney.Theremaininghotcoalswillcontributeadditionalheattothemass,andnoexcessroomairisintroducedintothehotinnerlife.

FIGURE11.9.TulikiviCorporationoftensuggestsback-to-backfiringsinheaterslikethis.Noticehowsoapstonegoeswellwithotherstoneandthetilefloor.Thisheaterfeaturesapanorama(multisided)door,large,rock-faced“bricks”thatarecarefullymiteredatthecorners,andsandblastedcarvingsinthestonecenteredabovethefirebox.PhotocourtesyofTulikiviCorporation.

ANoteAboutBack-to-BackFirings

Somemasonryheaterbuildersormanufacturerswillprovidefororevenencourageaback-to-backfiringmethod.Bythisitismeantthatyoucouldhavetheequivalentoftwofull-sizedfiresoneaftertheother—perhapsallinoneevening.Theideaoftheback-to-backmethodisthatyouchargethemasonryheaterwithenoughheatenergytolastalongerperiodoftime—usuallytwenty-fourhours.Notallheatersaredesignedforaback-to-backburn,soitisbestnottodosowithoutconsultingyourbuilderormanufacturer.Thekeyelementsherearetheabilitiesoftheheatertobothwithstandtheextra-hightemperaturesthatwillresultfromtwoconsecutivefiresandtheabilityoftheheatertostoresomuchheatenergyinsuchashortperiodoftime.Thereisnopointinburninganimmediatesecondfireifmostofthatheatcannotbestored(becausetheheateris“fullycharged”)andisjustsentupthechimney.Ingeneral,theproceduretofollowisthatwhenthefirstloadofwoodhas

burnedtoacoalbed,insteadofopeningthedoortorakethecoalsyoufillthefireboxwithasecondloadofwood.Thedoorisclosed,thewoodquicklyburstsintoflames,andthefiringprocessessentiallybeginsalloveragain.

FIGURE11.10.Thisisamasonryheaterandbakeovenandcookstove—fromnineteenth-centuryGermany!PhotocourtesyofVintageElements,Greenwood,SouthCarolina.

Forthoseheatersinwhichsuccessionfiringsareencouraged(oratleastprovidedasanoption),thepointtoemphasizeisthateverymasonryheaterisdesignedtoburnacertainamountoffueleverytwenty-four-hourperiod.Instructionsforback-to-backfiringarenotlicensebythebuilderormanufacturertoburntwiceasmuchfuel!Iftheheaterisdesignedtoconsume40poundsofwoodeachday,thentheback-to-backfiringshouldnotusemorethan40poundsofwood—perhaps20poundsintwoloads.Back-to-backfirescanbeusefulandconvenient.Ifyouknowthatyou’llbe

especiallybusythenextday,orifyou’regoingoutoftownforatwenty-four-hourperiod(ormore),thenyoumaywanttochargethemasswithasmuchheat

aspossibleallatonce.Ifyou’llhavenoopportunitytofiretheheateragainbeforetwenty-fourhoursisover,thiscanbeawaytokeepheatinthespace.Theothersideofthisissueisthatyou’llalwaysgetmoreevenheatingofthe

spacefromamasonryheaterthatisfiredonashorterinterval.Firingaday’sworthoffuelallatoncechargesthemasswithatremendousamountofheatenergy.Mostofthatheatwillbereleasedfromthemassinthefirsttwelvetosixteenhoursaftertheburn.Althoughtheheaterwillindeedstillbereleasingalotofheataftertwenty-fourhours,itwillbeconsiderablylessthanwhatwasreleasedinthefirsttwelvehours.Inthismanner,agreatertemperaturegradientwilloccurinthelivingspacebetweenthefirsttwelvehoursandthelastfewhoursofthetwenty-four-hourperiod.Ifyouwishtousethismethodonadailybasis,itisprobablybesttohavethe“doubleburn”inthemorning.Thisway,youenjoymaximumheatinthelivingspaceduringtheactivetimeoftheday;thereducedoutputoccurswhenthefamilyistuckedwarmlyinbed.(Ofcourse,thismaymeantheheaterisn’tathighoutputwhenthefamilygathersforbreakfast,butthatmaynotbeanissueformanypeople.)Forheatersgenerallydesignedformaximumoutputwithtwofiringsperday,

thereisaverysmalldifferenceintemperaturesoverthecourseofthedaywhenthosetwofiresoccurabouttwelvehoursapart.Themasonryheaterstaysmoreuniformintemperatureoveralland,thus,sodoesthelivingspace.Twofiresspacedequallyapartintimealsokeeptheinnerlifeoftheheatermorestableintemperature.Thecomponentsaren’tsubjectedtoquiteasmuchthermalshocksincetheinnerbricksareregularlyatahighertemperatureeachtimeafireisbuilt.Forthesereasons,Irecommendthattheback-to-backfiringmethodonlybeusedinunusualcircumstancesand,again,onlyiftheheaterisdesignedtobeusedthisway.

UsingaBakeovenManymasonryheatersintheUnitedStateshavebuilt-inbakingovens.Abakeoveninamasonryheaterisanaccessoryoroptionandisnotusuallytheprincipalreasonfortheheater’sexistence.Themasonryheaterismeanttoheatlivingspacefirst.Cookingfoodisasecondarypurpose.Therearethosewhobuildmasonrybakingovensthatarenotmasonryheaters.Certainlyanyonewhowantsbothamasonryheaterforheatingthespaceandawood-firedbakeovenspecificallyforbakingshouldconsultwiththeheatermason,whomayalsobe

versedinbakeovenconstruction,tocreateacomplexthatincludesallthedesiredelements.Inthissection,I’lldiscussusingthebakeovenaccessoryofamasonryheater.Inmostcases,thebakingchamberofamasonryheaterissubstantiallysmaller

thanitsmainfireboxchamber.Oneofthehallmarksofabakingchamber,inparticular,isthatitsceilingisquitelow,whereasthatisrarelyadescriptionofthefirebox.Thelowceilinggivesmanypeopletheimpressionthattheovenissmallandhaslimiteduse.Inthismodernage,peopleareaccustomedtothecavernousovenchamberofthetypicalfossil-fuel-firedorelectricoven.Insuchanoven,youcanputseveraltraysoffoodatonceonthevariousracks.Obviously,youwon’thaveseveralracksoffoodinanoventhatis,perhaps,lessthan12inchestallatitshighestpoint.Aswitheveryotheraspectofamasonryheater,thelowceilingofabakeoven

isentirelyfunctionalinnatureandrelatestothesuperiorbakingqualitiesofaheat-retainingbakingchamber.Whileaconventionalgasorelectricovencooksfoodentirelywithhotairgeneratedbytheburningfuelorhotelement,abrickorstoneovencooksfoodusingalltheavailabletypesofheat:thehotovensurfacesdoheattheairwithintheoveninamannersimilartoaconventionaloven.Also,however,everysurfaceoftheovenchamber—walls,floor,andceiling—isahotradiator,sendingdirectradiantheatatthefood.Foodisoftencookeddirectlyonthebrickorstoneovenfloor,exposingittodirectconductedheataswell.Noothertypeofovenwillcookfoodwithallthreemethodsatoncethewaythisovenwill.Thelowceilingisspecificallymeanttoaidinevenlyexposingthefoodtothe

finesthigh-intensityradiantheatandkeepsthewholeovenchamberataveryevenairtemperature.Ahigherceilingwouldreducetheradianteffectandintroducetemperaturestratificationintheovenchamber.Somemasonryheaterbakeovenswillalsohaveanarchedceiling.Again,thisisafunctionalelementthatmakestheovenceilingsimulateaparabolicreflectorthatconstantlydirectsitsheatataspecificpoint—thefoodonthecenteroftheflooroftheoven.Althoughyousacrificethequantityoffoodthatcanbeputintoabrickovenwhencomparedwithamodernconventionaloven,thesubstantialgainintasteandqualityofthecookedfoodiswellworththetrade-offtomostowners.

FIGURE11.11.Theshapeofthedoorisoftenahintastothegeneralsizeoftheovenoptioninamasonryheater.ThisisthebacksideoftheTulikivi“boulder”heatershowninfigure9.1.Thedoorisroughly16incheswideby10inchestall.Theovenisonlyalittlelargerthanthis.PhotocourtesyofWarmStoneFireplacesandDesigns.

It’simportanttonotethatthebakeovenaccessoryofmostmasonryheatersisonlyusableduringtheheatingseasonandprincipallyduringthecoldestpartoftheseasonwhentheheaterisalwaysathigherlevelsofoutput.Althoughsuchanovencanbeusedinsomewaysintheearlyfallandlatespring—asawarmingoven,forexample—generallyitisnothotenoughforseriousbakinguntiltheheateritselfisfiredregularlywithasignificantquantityofwood.Obviously,theoverallnumberofdaystheovencanbeenjoyedeachyearisdirectlyrelatedtothenumberofdaysthattheheaterneedstobefired.Someovens,asdescribedinthenextsection,maybeusableoveraslightlylongerperiodeachyearjustbecauseofthewaytheyarefired.FormosttemperatezonesoftheUnitedStates,thisstillmeanstheovenwillbefullyfunctionalsixmonthsoftheyearormore.MorenorthernareasoftheUnitedStatesandmostofCanadawillhaveabouttwo-thirdsoftheyearinwhichtobake.

ABlackandWhiteIssue

Therearethreetypesofbakingovensthatareinstalledasaccessoryitemsinmasonryheaters.Goodargumentsexistfororagainstallofthem,andyou’llhavetodecidewhichisbestforyoursituation.Therearewhiteovens,blackovens,andhybridversionsthatcanserveaseitherawhiteorblackoven.

BlackOvens

Ablackovenissimplyanoventhatactually“sees”thefireandsmokewithinitsconfines.It’scalleda“black”ovenforthesimplefactthat,likeanyfirebox,

blacksootwillsometimesaccumulatewithinit.Thesootdoesn’tgenerallysurvivelonginaproperlyfiredmasonryheater,sothenameissomewhatofamisnomer,butitconveysthefactthatsmoke,flames,andsometimesthefuelitselfarepresentintheoveninordertowarmittobakingtemperatures.Ablackovenonsomemasonryheatersistheprimaryfirebox(seefigure

11.12),butthisistheexceptionratherthantherule.Mostblackovensarechambersthataresomewheredownstreamfromtheactualmasonryheaterfirebox.ManyFinnishcontraflowdesignsincorporatethisfeaturebyplacingthebakingovenwheretheupperchamberoftheinnerlifeislocated.Sinceasecondaryburningchamberistypicalinthistraditionaldesign,turningitintoausefulbakeovenisacommonoccurrence.InthecaseoftheseFinnishdesigns,theflamesandexhaustofthefireoften

entertheoventhroughanarrowthroatsomewhereinthefloorofthebakeoven—ofteninthecenter.Inotherdesigns,theexhaustpathmayentertheovenfromasideorthebackandleaveeitherthroughanothersideorouttheovenceiling.IntheFinnishcontraflow,theexitisusuallyintheovenceiling.Someownersobjecttothe“hole”intheovenfloorcreatedbythethroat,and

othersthinktheycanjustcoverthethroatwithabakingstone—permanently!Thiswillnotwork,becausethethroat“hole”isessentialtotheflowofexhaustandflamesinthemasonryheater.However,whenthereisnolongeranyfireinthemasonryheater,anovenstonecanbesetintomakeacompleteovenfloorforbakingpurposes.Anownerwhodecidestodothismustremembertoremovethatstonebeforestartinganotherfireinthefireboxorberewardedwithsmokefillingthehouseinsteadofgoingupthechimney.Otherwise,panscanbeusedthatspantheopeningor,inthecaseofbread,loavescanbesetontheovenfloornexttothethroat.

FIGURE11.12.Thebakingchamberinthismasonryheateristheprimaryfireboxforwarmingthewholemass.Acookstoveisaddedtothesideofthebakeoven,turningthisintoacompletecookingcomplex.PhotocourtesyofTulikiviCorporation.

Anotherobjectionraisedaboutblackovensistheashitself.Sincethefireandexhausttravelthroughtheovenateveryfiring,ashwillaccumulateontheflooroftheovenonaregularbasis.Inawood-firedovenusedspecificallyforbaking,thebakernormallyswabstheovenfloorwithanovenmopbeforebaking.Thisnotonlycleanstheovenfloorbutalsointroducesadditionalmoistureintotheoven,whichcomplementsthebakingprocess.Masonryheaterownerswoulddowelltoimitatethisbehavior.Forthoseheaterswithanopenthroatintheovenfloor,thebulkoftheashcanbesweptoutoftheovendownthatthroattothefireboxbelow.Inotherdesigns,aspecialashdumpmayhavebeenprovided.Ifnot,anythingbutadustingofashwillhavetobescoopedoutbeforeswabbingtheovenfloor.

Despitethelevelofmaintenancerequired,theblackovenhaspeculiaradvantages:becauseitisdirectlyexposedtothefireandexhaust,itgenerallyheatsquicklyandachievesveryhightemperatures.Also,thewaitingtimeforuseofthenewlyintroducedheatisgenerallyprettyshort.Oncethefireinthe

masonryheaterisout,usuallyawaitisrequiredtoallowtheoventemperaturestostabilize.Immediatelyafterthefire,somepartsoftheovenmaybedramaticallyhotterthanothers.Awaitingperiodofapproximatelyanhourallowsthosetemperaturestobecomemoreeventhroughouttheoven.Yetthosetemperaturesareveryhighandwillprovide,inthehoursfollowing,thefullrangeofbakingoptions.Youcanstartwithpizzasorunleavenedcrackerswithhightemperaturesof600°Formoreandproceedthroughthedaywithbreadsat450°,piesorcookiesorcakeat350°,andstews,soups,orporridgeatlowertemperatures.

FIGURE11.13.BetweenthebakingloavesofbreadisthethroatofthisFinnishmasonryheater.ProjectbyMarenCookeandKenMatesz;photobyMarenCooke.

Althoughsomeblackovenchamberscanserveastheplacetoloadandburnfuel,thisusuallyisnotdonesincetheovenisdirectlyexposedtothefluegasesanyway.Forinformationaboutburningfiresdirectlyinabakeovenchamber,seethe“White/BlackHybrids”section.

WhiteOvens

Thetermwhiteovenstemsfromthefactthatitiscleanor“white”;fuel,smoke,orflamesneverseetheinsideofthebakingchamber.Awhiteoveniswarmedfromtheoutsidein.Inmostinstallations,themasonryheaterfluesaredesignedto,insomeway,surroundorcontactthesides,top,andbottomoftheoven.Theovenfloororsidesmayactuallybestructuralwallsofsomeoftheseflues,ortheovenmaybea“box”setintooramongtheflues.Eitherway,theovenisalwaysfreeofsootandash.Itisanovenmorecomparableinoperationtoaconventionaloveninthattheheatsourceisoutsidetheoven.Likeaconventionaloven,awhiteoveninamasonryheaterisusableanytime

sincethereisnofireorsmokeinit.However,likeablackoven,itisusuallyonlyatevenandpredictabletemperaturesduringtheperiodafterafirehasbeenburnedratherthanduringafire.Youcouldputfoodinawhiteovenwhilethemasonryheaterisbeingfired,butbeawarethatthetemperaturesintheovenwilllikelyberisingthroughoutthattime.Aswithablackoven,particularsidesoftheovenmaygetwarmerduringthefireorimmediatelyafterthefiregoesout.Lettingtheovenrestforaperiodoftimeallowsthetemperaturestostabilizeformorepredictablebakingresults.Thoughawhiteovenoptionisalwaysclean,itmayhaveitsowndrawbacks

dependingentirelyonthedesign,knowledge,andskillofthebuilder.Itshouldbeemphasizedthattheprimarypurposeofamasonryheateristoheatlivingspace,nottocookfood.Goodheaterdesignshouldfirstaccomplishthisgoalwhilethebakingchamberperformanceshouldbeasecondaryobject.Ifcookingisyourprincipalgoal,itisnotamasonryheaterthatyounecessarilywant.Twoofthepotentialweaknessesofawhiteovenarelowerachievabletemperaturesandshortertotalbakingtime.Thefartheralongthefluepaththeovenisfromtheprimaryfirebox,theless

hottheovenwillget.Anovenexposedtofluegasesdirectlycomingoutofthefireboxwillgetmuchwarmerthanonethatdoesnotencounterexhaustuntilithastraveledmanyfeet.Someoftheheatofthefirewillhavebeenabsorbedintheprecedingfluesandwillnotbeabletochargetheoven.Likewise,someovensmayhaveonesurface—thefloor,forexample—exposedtothehottestpartofthefire,likeanovendirectlyabovethefirebox.Yetifthewallsandceilingofsuchanovendonot“see”anyexhaustuntilseveralfeetoffluehavebeentraveled,theovenstillmaynotgetashotasyou’dexpect.Oftenthedesiredlocationoftheoven,thedesignoftheheaterandflues,and

thedemandsofcreatingthebestheaterpossiblemaynecessitatethecreationofalessperfectoven.Trade-offsmaybenecessarydependingonwhatismostimportanttoyou.Ifyouwanttheoventofacethekitchen,yetthatsideofthemasonryheaterisfarfromthefirebox,you’llmakeasacrificeinovenperformance,whilelocatingtheovenclosertothehottestpartoffiremaymakeitlessconvenienttothekitchen.

FIGURE11.14.Awhiteoveninaheaterunderconstruction.Theopeninginthebackisacleanoutaccesstofluesbeyond.PhotobyJulieCline.

Thewhiteovenalsomaynotofferasmuchtimeforbakingbecauseitdependsentirelyonthetimedelayofheattravelingthroughthemasonrymaterialstogettotheinnerovenenvironment.Thisdelayisunliketheblackoven,whichisincrediblyhotimmediatelyafterthefiredies.Thelengthofthedelaywilldependonthethicknessofthematerialsaswellastheircharacteristics(seechapter6).Withthinnermaterials,theovenmaygethotquitefast,butitwillalsocoolquicker,whilewiththickermaterialsitwilltakelongerfortheoventogetwarmandthethicknessmayresultinloweroveralltemperaturesoncetheheatdoestransfer.

White/BlackHybrids

Anoventhatisusableasbothawhiteovenandablackovenismoreversatilethaneitheronebyitself.However,noteveryheaterdesigncanaccommodatesuchahybrid.Thewhite/blackhybridisdesigneddifferentlythanatypicalblackoven.Itisitsownfireboxanditneverseesfire,flame,orsmokeunlessyouintentionallybuildafireinit.Thusitisusuallywarmedbythefireoftheprimaryfireboxofthemasonryheater.Itsversatilitystemsfromthefactthatinwarmerweather,whenyoumaynotwanttofirethemasonryheaterhotenoughtofullychargeawhiteoven,theovenitselfcanbefiredspecificallyforbaking.Youcanseetheinsideofsuchahybridoveninfigure11.15.

FIGURE11.15.Awhite/blackhybridovencanbeusedeitherasacombustionchamberorasawhiteoven.Inthecenterbackoftheovenisanashdumpdoor.Intheupperbackisadampertoopentheoventothefluesoftheheaterwhenusedasacombustionchamber.

Awhite/blackovenusuallyhasadoorordamperofsomekindconnectingittothefluepathofthemasonryheater.Thisconnectionneedstobeopenedinordertousetheovenasafirebox,andsuchausegenerallyprecludesthesimultaneoususeofthemainmasonryheaterfirebox.Ontheotherhand,somecleverdesignsprovideseparatefluepathsforthemasonryheaterandthebakeovensotheycanbeusedatthesametime.Themasonryheaterandoveninthiscaseareessentiallyseparateappliancesmeldedtogether.Dependingonthetotalconfiguration,thebakeovenpartmayormaynotbeconsideredamasonryheater.Itmaysimplyhaveaflueexitthatfeedsdirectlyintoachimneyratherthanadditionalfluestowarmthemasonrymass.

FiringandRegulatingaBlack(orWhite/Black)Bakeoven

Overall,themethodoffiringablackbakeovenissimilartofiringthemasonryheateritself.However,asnotedearlier,thebakeovendoesnothavethevolumeofthemainfireboxofamasonryheater.Itisunlikelythatyoucanloadafullcomplementoffirewoodinabakeovenallatonce.Inmostcases,thebakeovenisanaccessoryforbaking,notafireboxdesignedtochargethewholemasonryheatermasswithheat.Thebakeovenisfired,therefore,inasomewhatmoreintermittentmannertoachievethedesiredbakingtemperatures.Ifyou’replanningadayofbakinginablackoven,itisagoodideatostarta

dayinadvance.Inasolelywhiteoven,thewarmthanduseoftheovenareentirelycontrolledbyburningwoodinthemasonryheaterfirebox.Thewhiteoventemperaturesareentirelyrestrictedbyhowmuchfuelcanbeusedinthemasonryheater.Withawhite/blackoption,youcanfirethemasonryheaterthe

eveningbeforebakingdaytogettheoventosomeincreasedtemperature.Then,earlyonbakingday,firethebakeovenitselftoachievethetemperaturesatwhichyou’dliketostart.Sincethebakeovenisprewarmedfromthepreviousevening,theprocessdoesnottakelong.

FIGURE11.16.AcutawayviewshowsthesmokepathfromablackoveninaFinnishcontraflowdesign.Theexhaustgoesbrieflyup,thendownbothsidesbeforeexitingintoachimneyconnector.IllustrationcourtesyofTulikiviCorporation.

Likethemasonryheaterfirebox,theblack/whiteovenwillhaveanairintake—oftenaspartofthedoor—whichmustbeopened.Asmentionedearlier,thereislikelyadoorordamperthatmustbeopenedbeforeloadingandburningwoodintheovenaswell.Likewise,ofcourse,thechimneydamper(ifequipped)mustbeopen.Inthebakeovenfirebox,itisagoodideatousesmaller-diameterwoodthan

yougenerallydointhemasonryheater’sprimaryfirebox.Sincethevolumeissmaller,thetotalquantityofwoodusedallatonceisless.Smallerpieces—perhaps2to3inchesindiameter—willmorereadilyachievethehightemperaturesneededforcleancombustioninthislimited-spaceenvironment.Thereisnoroomforatepeefireinthebakeoven,sothewoodshouldbeloaded

inacribfashionasdescribedpreviously.Ingeneral,top-downorbottom-upisirrelevantinthiscompressedenvironment.Startthefireburningwithnewspaperandkindlingorfirestartermaterial.Somemasonryheaterbakeovenswillbeequippedwithalong-stem

thermometerthatreachesintothestonesorbricksoftheovenchamber(seefigure11.17).Ifsoequipped,youcanmonitorthetemperatureasitrisesduringfiring.Youmayneedtoreloadtheovenwithfueloneormoretimestoachievethedesiredtemperatures.(Aswiththemasonryheateritself,ifthebuilderormanufacturerprovidedinformationaboutthemaximumamountofwoodtobeburned,thislimitshouldnotbeexceededintheoveneither.)Unlikeaconventionaloventhermometer,thisembeddedthermometerismeasuringthetemperatureinsidethemassofthestructureratherthantheairtemperatureintheoven.Atemperatureof350°Finthemassisnotthesameasa350°airtemperatureinaconventionaloven.Itislikelythatiftheinnermassis350°,thetemperaturewithintheovenchamberishigherduringafireorjustafterafirehasbeenburned.(Itisnotpossibletoinsertanormaloventhermometerinthebakingchamberwhilethefireisburning.Manyathermometerhasbeendestroyedbybeingforgotteninthebakingchamberwhenablackovenwasfired!)Learningtobakeinamasonryheaterbakeovenisamatterofdevelopingnew

skillsandawareness.Youmayhavenoexperiencewithdrivingacarwithastandardtransmission.Yetdrivingthatcarisn’tallthatdifferentfromdrivingonewithanautomatictransmission.Afewnewskillshavetobemastered,andbeforelongtheybecomesecondnature.Apersonwholovestobakewillfindthatmostbakingskillsreadilytransfertousingawood-firedoven,butitmaytakealittletimeandafewerrors.Itdoesnottakelongforexperiencedcookstomasterthepeculiaritiesofawood-firedoven.Likelearningtodriveastickshift,itjusttakesalittletimeandattention.Whenthedesiredtemperatureisnearlyreached—itiswithin,say,25°F—no

morewoodshouldbeaddedtothefire.Youcancheckthetargettemperatureusingthebuilt-inthermometer,apoint-and-shootinfraredthermometer(seeappendixA),orbyexperientialmethodssuchasthrowingcornmealonthehearthtoseehowquicklyitbrownsorblackens.Eventually,ardentbakersbecomeintimatelyfamiliarwithhowmuchwoodproduceswhatbakingrangeoftemperatures.Youcanalwaysinsertastandardoventhermometerafterthefireisout.Still,abrickorstoneovenatagiventemperaturegenerallyperformslikeahotterstandardovenbecauseitcookswithradiant,convection,andconduction

heatsimultaneously.Thereisnoescapingtheneedtorelearntheartofbakinginaheat-retainingoven.Cookingpizzaandotherflatbreadsontheovenfloorisoftendonewithred

hotcoalsstillintheovenchamber,pushedtotheedgestomakeroomforthefood.Formostotherfoods,thecoalsareremovedfirstbeforebaking.Some,butnotall,masonryheaterblackovenswillhavesomekindofhatchorothermeanstopushcoalsoutoftheovenchamber—usuallytofallintoeitheranashpanorintothemasonryheaterfirebox,wheretheywillfinallyextinguish.Inthelattercase,bemindfulofhavingsomeairsupplytothoserejectedcoalsaswellasaroutefortheescapeoftheremainingexhaust.Thisisusuallyaccomplishedbyresettingthebakeovendampertotheplacethatisrequiredwhenthemasonryheaterisoperatednormally.Inanovenwithoutahatchtodumpcoals,youmayneedtoshovelcoalsout—puttingthemintoametalcontainerandremovingthemfromthehouse.Thelatterisgoodreasontospecifywiththemasonryheaterbuilderthatacoalhatchmustbesupplied.

FIGURE11.17.Along-stemmedthermometerregistersthetemperatureofthemasonryabovetheoven.ThisonereadsindegreesCelsius.

Thenextstepafterremovingcoalsistolettheovenrestforawhiletoallowthetemperaturestostabilize.Foraperiodoftimeafterthecoalsarefirstremoved,theovenmaystillriseintemperatureslightlybeforesettling.Afterahalftoonehour,theovenshouldbereadyforbaking.Ifit’sstilltoohotforyourrecipe,allyoucandoiswaitwhilethebakeovenslowlycoolstothetargettemperature.Again,experiencewillmakethiskindofwaitlesslikelyinthefuture.Awell-constructedwhite/blackovenfiredasoutlinedherewillprovidemany

hoursofcookingtimewithtemperaturesstartingquitehighforpizzasorbreadandeventuallycoolingtoasteadyheatjustrightforcookingstewsorsoups.Whenitfinallycoolstoboilingtemperature,thebakeovenisjustrightforcookingporridgeovernightforawonderfulhotcerealinthemorning.Therereallyareveryfewthingsthatcannotbecookedinamasonryheater’sbakeovenonceyou’vetakensometimetoobserveandexperimentwithit.

FIGURE11.18.Awell-designedmasonrycookstoveaddstremendousversatilitytoheatingwithwood.Thismodelhasbothafunctionalcooktopandabakeoventhatcanbefiredseparately.PhotocourtesyofTulikiviCorporation.

TheMasonryCookstoveAmasonrycookstoveisusuallyaseparatelystanding,peculiarmasonryheaterthathappenstohaveacast-ironcooktop.Althoughacooktopcanbeintegraltoalargermasonryheater,thisisnotoftenthecase.Andwhileamasonrycookstoveisamasonryheaterhavingflueswithinitsmassfortransferringheatforretentionandlaterradiation,italsoactsinsomewayslikeametalwoodstove.Mostmasonrycookstovesaredesignedtohavetheflamesandexhaustofthefire

contactthemetaltopfirst,providingheatto“burners”onwhichyoucanthencookfoodorheatwater.Thismetalcooktop,then,becomesaquitehotradiatingsurface.Yetbecause

oftheinternalfluedesign,themasonrywillstoresignificantamountsofheatforlateruse.Inthisway,themasonrycookstoveisaversatileappliance.Itcanproduceexceptionallyquickheatalmostimmediatelytothelivingareaalongwithstoredheatforlonger-termheating.Itdoesthiswhilealsofryingeggs,boilingwater,andsimmeringsoup!Somecookers,ascookstovesarefrequentlycalled,alsoincorporateeitherawhiteorablackoven(seefigure11.18).Thecookerthenbecomesanamazingdevicethatcanbeusedtocookanydishafamilymaywantwhilecontributingtotheheatingrequirementsofthehouseaswell.

FIGURE11.19.Abetterviewofthecookstoveintheheaterseeninfigure11.1.Theovenevenhasaglassdoor.PhotocourtesyofMaineWoodHeatCompany.

FiringaCookstoveAllthesamebreak-inproceduresusedforanewmasonryheaterapplyequallytoanewcookstove.Liketheblackbakeoven,amasonrycookstoveisbestoperated

usingsmallerpiecesofwood.Thefireboxforacookerisevensmallerthanthatofanovenanddoesnotreadilyacceptlargepiecesofcordwood.Firewoodpieces1to2inchesindiameterareexcellentforthispurpose.Becauseofitssmallfireboxsize,whichmaybeasnarrowasabout7inches,thecookstovewillneedtobefiredinamorecontinuousfashionthanatruemasonryheater,especiallyifthecooktopistobeusedforanextendedtime,tobothheatthecooktopandchargethemasswithheat.Again,likeitslargerandheaviercounterparts(full-sizedmasonryheaters),itshouldnotbefiredwithmoretotalfirewoodthanisrecommendedbythebuilderormanufacturer.Thefirststeptofiringistoopenthechimneydamper(ifequipped)andto

makesurethecookstovehasadequatedraft.It’salsoagoodideatoremoveexcessashfromthefireboxandtomakesuretheashpan(ifequipped)isnotfull.Dependingonthedesign,thecookstovemayhaveaspecificair-supplyvent,slidesforairinthedoor(s),oritmaybefedbycrackingopenthefireboxorashboxdooritself.Theairsupplyshouldbeopenedbeforelightingthefire.Loadthefireboxwithkindling,newspaper,andoneortwopiecesofthemainfuelload.Thenlightthefireandmonitoritregularly,becauseyou’llneedtoaddmorefuelatfairlyregularintervalsuntilthemaximumweightoffuelhasbeenconsumed.Usually,nomorethanabout5poundsofwoodcanbeburnedatonetimeinthesmallfireboxofacookstove.Asinanymasonryheater,thefireshouldburnbrisklyandwithlittlesmoke.

Dry,smallpiecesoffirewoodshouldburnwithbrightyelloworevenwhiteflamesandproducequickheattothemetalcooktop.Adjusttheairintaketoguaranteeplentyofairtothefire.Cookstoves,likeallmasonryheaters,arenotmeanttobeoperatedinadampenedfashion,starvingthefuelofoxygen.Dependingonthesizeandspeciesofwoodused,you’llneedtofeedthefireagaineveryhalfhourorsountilyou’redoneusingthecooktoporyou’veusedtherecommendedweightoffuel.

FIGURE11.20.Auniqueandfunctionalcookstoveandheaterinhandmadetiles.Itisn’toftenthatweseearoundcookstove.Kachelofendesigned,built,andphotographedbyErnstKiesling,CanadianKachelofen.

Atthispoint,youcanletthefuelloadburntocoals.Whenthereisnomoreflame,evenwithalightstirring,closethechimneydamper(ifequipped).Whenthecoalsareallconsumedandturnblack,indicatingnomorefire,closetheairsupplyaswell.

UsingtheCooktop

Thecast-ironcooktopofamasonrycookstoveisusuallycoatedwithaprotectiveoiltopreventrustingduringstorageandshipment.Theoilisharmlessandwillburnoffwhentheapplianceisfired.Itmay,however,produceanacridodor.Ifoneisavailable,useanexhaustventwhenyoufirethecooktopthefirsttime.Otherwise,itisadvisabletobreakinthecooktopduringweatherinwhichyoucanopenawindowordoortoreleasethis.Otherwise,thefirstuseofacookstoveistheequivalentofthefirstuseofmostmasonryheaters.

Likethebakeovenaccessoryofamasonryheater,amasonrycookstoverequiressomebasicretrainingofcookinghabits.Unlikeamodernrange,itisnotpossibletosimplysetaburnerat“high”or“low.”Thestovetoplocationsclosesttothefireboxwillalwaysbethehottestandareidealforboilingwaterandothertasksthatrequirethehighesttemperatures.The“burners”orhobs,astheyarecalled,farthestfromthefireboxwillbemoresuitableforthemediumandlowertemperaturesneededforsimmering.Ateakettleorpanofwatercanbeaneffectivegaugeofthetemperatureatfirst,butwithexperienceyou’llgetafeelforthecorrecttimetousethevariousstovepositionsbasedonthequantityoffuelusedandthetimethathaspassed.Cookinghasalwaysbeenanart,andwood-firedcookingraisesthatartformtoanewlevel.You’llgetthebestuseofawood-firedcookstovebyusingcast-iron

cookware,thoughthisisnotarequirement.Likethecooktopitself,cast-ironcookwarestoresmoreheatthanthinnersteeloraluminumpansandwillhelptomoderatetemperaturefluctuationsasafireburnsthroughitscycleofignition,fullcombustion,andcoalstages.Thismoderationoftemperaturescanbeaugmentedfurtherbyalwayskeepingalargepotofwateronthestovetop.Thinsteelpanswillhavetheirplace,andtheaccomplishedcookwillhaveaninnatesenseaboutwhentousewhichpansforwhichpurposes.Aswiththemasonryheaterbakeoven,thereisnosubstituteforexperimentationandexperience,whichwillservetohonetheskillsofeverycook.Itisbestnottofirethestovecontinuouslywithoutactuallyheatingsomethingonthetop.Thecastirontop,subjectedtotheintenseheatwithnothingtomoderateit,canbestructurallydamaged.Themetalcooktopcanbeeasilycleanedwithtypicalkitchendishwashing

soapandwater.Stubbornspillsorruststainscanbedressedwithfinesteelwoolaswell.Thoughthisisn’tnecessary,itisbestthatyoucoatthecast-irontoplightlywithvegetableoilwhenyouwon’tbeusingitforalongperiodoftimetopreventrusting.Aswiththeoriginalcoating,thiswillharmlesslyburnoffthemetalwhenyouusethecookstoveagain.

ConclusionAmasonryheaterisveryeasytouse,andlearningtoheatwithamasonryheater,useitsbakeoven,andcookonacookstoveisrewardingandquick.Itwasnotthatlongagothateveryoneheatedandcookedwithwood.Manywhohave

grownupwithmodernappliancesare,atfirst,overwhelmedbywhatmustbedonetoheatandcookwithwoodusingheat-storagetechnologies.Oncetheskillsarelearned,however,theybecomesecondnature.What’smore,theprocessisn’ttimeconsumingconsideringalltherewardsofgentle,healthy,radiantheatandtheuniqueflavorsoffoodcookedinawood-fired,heat-retainingoven.Masonryheaters,blackbakeovens,andcookstovesalloperateonthesame

basicprinciples.Eachneedstobegentlybroughtuptotemperaturewhennewlyconstructedorafteralongperiodofdisuse.Oncewarmedandusedregularly,amasonryheaterfireboxisalwayswarmandconducivetoquickfirestarting.Thechimneymustbeclearandopen,airsuppliesmustbeopen,andthefireboxand/orashpansmustbefreefromexcessash.Kindling,newspaper,andmainfuelchargesareloadedinquantitiesrecommendedbythedesigner,builder,ormanufacturer.Oncethefireislit,youcansitbackandenjoyuntilitnaturallyextinguishesitself.Aslongasthefireburnsbrisklyandbrightly,thereisnothingmoreyouneedtodo.Afewminutesoffirebuildingresultsinmanyhoursofradiantheat.Amasonryheatercouldbecalledthelazyman’swaytoheatwithwoodsinceitrequiresnopokingorprodding,continualadditionoffuel,orotherconstantattention.

FIGURE11.21.Anall-tileheater,oven,andcookstovedesigned,built,andphotographedbyErnstKiesling,CanadianKachelofen.

FIGURE12.1.Amassivefive-sidedstonemasonryheateroccupiesthecornerofthiscentralspace.Thegiantchimneyhugsthecornerallthewaytothetallcathedralceiling.PhotocourtesyofTemp-CastEnviroheat.

CHAPTERTWELVE

MasonryHeaterMaintenance

Igrewupinabrickranchhouse.Myparentsraisedmewithagoodworkethic.Myfather,whileIwasayoungster,almostneverhiredanyonetofixanything.Herepairedcars,dishwashers,dryers,furnaces,andrefrigerators.Everythinghefixed,hecleanedthoroughlysoitlookedlikenewagainwhenhewasdone.MymothercleanedthewholehousereligiouslyeveryThursday.Thekitchenwasalwaysspotless.Sheneverwenttobedwithadirtydishinthesink.Outside,mymotherwasusuallytheonetopainttheoverhangs,paintthefrontdoor,andwashthewindows.MybrotherandIhelpedwiththesetasks.Iwasoftenthe“gopher”forDad.Iwould“gopher”thescrewdriver,then“gopher”thewrench,and“gopher”thepaint.WhenIthinkbacktoallthehomemaintenanceandrepairprojectsmyparents

andIgotinto,allthecleaning,allthescrubbing,allthemeticulouscareofeveryaspect,IcannotrecallonesingletimethatanythingwaseverdonetomaintainthebrickfacadeofthehouseinthetwentyorsoyearsIlivedthere.Ineversawitwashed,scrubbed,orrepaired.Theystillliveinthatsamehouse.Afterfortyyears,thatbrickonthehousestilllookslikenew.That’swhatit’sliketomaintainmasonry.Ofcourse,amasonryheaterisdifferentfromjustabrickwall.Ontheother

hand,myparents’brickwallshavebeenexposedtodrivingrains,wind,freezingtemperatures,heatwaves,sunshine,andeveryothermannerofweathersincethehousewasconstructedinthe1950s.Masonryveneersinsidethehousehavetheeasylife,incomparison.Butthemasonryheater,asawhole,isaworkhorsethattoilssixoreightmonthsoftheyear,thengetsasummerbreak.Whenitgoesonbreak,itbehoovesyoutopamperitsome—giveitaspatreatmentifyouwill—sothatitwillbewellrestedandrejuvenatedwhentheweatheragainturnscold.

After-SeasonMaintenance

Whenitisclearthatthemasonryheaterwillnotbeusedforheatinguntilthenextheatingseasonarrives,therearesimplemaintenancetasksthatarebestdonerightawaytokeeptheheaterinthebestcondition.Throughouttheheatingseason,timedevotedeachdaytoretrievingfirewoodandloadingitintotheheaterwasminimal.Abouttenminutes—fifteenminutestops—isrequiredtostartafireandsubsequentlyshutdowntheheater.Theyear-endtasksaren’tmuchmoredemanding.

GeneralAshRemovalIt’sagoodideatoremoveallaccumulatedashfromthefirebox,ashpan,orotherashcollectionarea,andablackbakeoven.Ashesarehygroscopic,meaningtheyreadilyabsorbmoisture.Sincemoistureisthenumberonethingnotdesiredinamasonryheater,it’sagoodideatoremovealltheashes.Ashmixedwithmoisturebecomeslye—acorrosivealkalinesubstancethatisthebasisoflyesoap.Wetashescanburntheskin,andlyeitselfhasbeenobservedcorrodingevenglass.Thisiswhyitshouldberemovedascompletelyaspossible.Thefireboxcaninitiallybescoopedwithafireplaceshoveloragardening

trowel,ascantheotherareas.Somemasonryheaterswillhaveashdumpsthatdirectashesdownintothefoundationcavity.Otherswillhaveremovablemetalboxestocollectandremovemostoftheash(seefigures12.2and12.3).Oncethevastmajorityoftheasheshavebeenremovedwithashovelorabox,useashopvacuumfittedwithaqualitydustbagtoremovetheremainder.Itisalsopossibletobuy,throughahearthretailer,specialvacuumsdesignedspecificallyforcleaningashes.SeeappendixAformoreonashvacuums.

FIGURE12.2.Ifequipped,theashboxdoorisusuallyrightbelowthefirebox.

FIGURE12.3.Anashboxreadytobeemptied.

Theashanddustremainingfromburningwoodinamasonryheatercanbefineenoughtosliprightthroughconventionaldustbagsonregularsweepers.Youcanendupusingthevacuumasablower,spreadingfinedustalloverthelivingarea,unlessyouusetherightvacuumandbags.Ifyou’reindoubtabouthowwellavacuumwillcontaintheash,takeitoutsideanduseittovacuumashoutofacontainerinwhichmostoftheashwascollected.Ifthevacuumsuckstheashinanddoesnotspewdustoutitsblowerports,itwillprobablybeallright.Otherwiseitwillbebettertoobtainbetterbags,getadifferentvacuum,orjustsweepouttheheaterbyhandasthoroughlyaspossible.Iftheheaterwasbuiltsothatashcouldbedumpedregularlydownintoa

foundationcavity,springisalsoagoodtimetoemptythis.Thereshouldbea

cleanoutdooreasilyaccessibleinthebasementorcrawlspace.Usuallythisisahatchabout8inchessquare,aswasseeninfigure9.6,thoughbigger(andsmaller)onesaresometimesused.Liketheheateritself,thiscanbeprimarilyemptiedwithashovel,thenvacuumedclean.

ChimneyCleaningThosewhoownandthosewhobuildmasonryheaterswillgivevariedanswersastohowoftentohavethechimneyinspectedandcleaned.Twoofthemostfrequentlyaskedquestionsaboutmasonryheatersandtheiroperationarehowmuchcreosotecollectsinthechimneyandhowisitremoved.Chapter4addressedcreosoteinmoredetail,butaproperlyconstructed,well-designed,andproperlyfiredmasonryheaterwillnotdevelopcreosoteinthechimneylining.Ifanappliancedoesnotdevelopcreosote,therereallyisnothingtocleanfromthechimney,thoughsomeflyashmayaccumulateatitsbase.Itisbesttoerronthesideofcaution,however,withanewheater.Novice

operatorsmaynothaveproperlyfiredthemasonryheater.Thereisachancethatgreenorwetwoodwasused.Somepeoplehaveburnedthingsnotrecommendedasfuelinamasonryheater.Perhapsthemasonryheater,ifpartofaremodelingjob,wasconnectedtoachimneythatwasalreadylinedwithcreosote.Thesepossibilitiesaregoodenoughreasontohavethechimneyofanewmasonryheatercheckedafterthefirstseasonofuse.Ifthereareundesirabledepositsontheinsideofthechimney,itisamessagetothehomeownerthatsomethingisnotright;themostlikelyculpritiswoodthatwasnotsufficientlydry.Aprofessionalchimneysweepshouldbeabletodetermine,basedonthisfirst

inspection,howoftenthechimneyreallywillneedcleaning.Onewhofindsachimneythatstilllookslikeit’snewwithjustasmallaccumulationofflyashatthebasemaysuggestthatthechimneyneednotbeinspectedeveryyear.Youcandoasimplecheckaswellbyopeninganearbycleanoutandusingamirrorpositionedtolookupthechimney.Indaylight,youshouldbeabletoseeifthewallsofthechimneylooksmoothandcleanorroughwithacoatingonthem.Aproperlyoperatingchimneywillhavetheformerappearanceyearafteryear.Mymasonryheaterchimneyhasbeenusedforfifteenyearswithnoaccumulationinit.

AshRemovalThroughSootPlugs/Doors/Cleanouts

Ifthechimneysweepdoesbrushthechimney(fromupontheroof),thedebriswillfalltothebase.Thereshouldbeacleanoutaccesstogettotheareabelowthechimney.Oftenitisaccessedthroughoneofthesootplugsordoorsinthesideofeithertheheaterorthechimneyitself(seefigure12.4).Theheateritselfshouldhaveanumberofcleanoutopeningsandaccompanyingsootdoorsatallthecruciallocations.Usually,ateveryplacethattheinternalflueschangedirection,therearesootplugs.Ifachimneysweepisonsitetocleanthechimney,there’sapossibilityheorsheisalsoknowledgeableenoughtocleanthefluesoftheheaterthroughthevariouscleanoutaccesses.Thedesignerorbuilderofthemasonryheatershouldbeabletogive

suggestionsastohowoftenyoumustopenthesedoorsorremovethesootplugstoclean.Somewillsaythisneedstobedoneannually,whileothersfeelthatseveralyearscanpass.Thereisno“right”answertothisexceptwhatisrecommendedbythemakerofthemasonryheaterandwhatyoulearnbyuseandexperience.Aswiththechimneyitself,ifyoucheckinsidetheheater’scleanoutopenings

andfindalotofashafteroneyear,itmaybeamessagethattheheaterdoesneedthisserviceannually.Ifinspectionafterthreeyearsfindsalmostnoashaccumulation,thenitisclearthatseveralyearscanpasswithoutcleaningthroughthesootplugs.Generally,themoreaccuratelyandpainstakinglyamasonryheaterwasdesigned,thelessoftenthechimneywillneedtobecleaned,simplybecausetheheaterburnsthewoodmorecompletely.Bearinmindthatachangeinthespeciesofwoodyou’reburningcaninfluenceashbuildupaswell.

FIGURE12.4.Sootplugsareremovedannuallytoaccessthefluesofthemasonryheater.Theaccessholeisusuallylargeenoughforashopvacuumhose.

FIGURE12.5.Someofthecleanout(soot)doorsavailable.Bothoftheblackdoorsareheldintotheirframesbygravity.Thesoapstoneplugfitsbyfrictionofthefiberglassropeinsideasawn-outcircle.Seefigures2.1and7.16forsquaretilecleanoutcoversthatareheldinbyclaymortar.

Theactualcleaningthroughthesootdoorsissimpleandnotverytimeconsuming.Onmanyheaters,thesootdoorsaremetalandheldinplacebygravitylockingeitherapinorcastingbehindamanufacturedcatch.Othersareplugsthatfitsnuglyintoaholeandareheldinplacebythefrictionofabandoffiberglassropeortapeagainsttheinsideofthehole.Yetothersareheldinplacebyaclay-basedmortar.Somewillhavethemetaldoorontheoutsidebutaninnerplugheldinplacewithaclaymortar.Somewillhaveboththeinnerandouterdoorsheldinplacewithclay.Inthecaseofsootdoorsheldbyclaymortar,youmaywishtohavetheheatermasonreturntoreinstalltheplugaftercleaning(orhavethemasondotheactualservice).Oncethesootdoorisremoved,youcanlookinsidetheopeningorfeelinside

withahandtoseetowhatdepththeashhasaccumulated.Thebuilderordesigneroftheheatermayhaveprovidedbasicinstructionsordrawingsshowingthecleanoutsandwhatareasyoushouldbeabletoreachandcleanthroughthosecleanouts.Ifthereisalotofashandtheaccessislargeenough,itispossibletouseasmallshovelortroweltoremovethebulkoftheash.Otherwise,useagoodvacuumwithadustbag(andonlyiftheheaterhasbeenunusedlongenoughthatnothingiswarmanymore!)toreachalltheaccessibleareas.Onceagain,asmallmirrorisahandydevicetolookinsidethevarioussoot

doorstoverifythatcleaninghasbeenthorough.Somehardwarestorescarrymirrorswithauniversaljointonalongrodsothatyoucanadjustthemirror,insertitintosuchacavity,andseeinvariousdirections.Notbeingequipped

withoneoftheseisnoliability.Attheveryleast,insertthevacuumhoseintothecleanoutandmoveitinalldirectionstogetasmuchdebrisaspossible.Cleaningthroughthesootdoorswithavacuumshouldonlytakeanhouror

lessformostmasonryheaters.Ifyouplantodothis,it’swisetowearoldworkclothesandlayatarp,blanket,sheet,orevennewspapersundertheareaofthecleanoutstocatchanyashthatmayescape.Ifthebuilderordesignerofthemasonryheatersupplieda“map”oftheflues,itwillbeeasytoknowwhichdirectionstosendavacuumhose.Thissimpleinvestmentoftimeattheendofaheatingseasonassuresmaximumperformanceoftheheaterinthefall.

DoorGlassCleaningTherearemanydifferenttypesofdoorsavailableformasonryheaters,andsomestaycleanerthanothers.Forexample,somehavedoubleglazing—twopanesofceramicglassseparatedbyairspace.Thisarrangementmeanstheinnerpaneofglassgetshotterthanasinglepanewould;itismuchmorelikelytostaycleansincesootthatmightgetonit(likefromalogfallingagainstit)willburnofftheglassbecauseofthesuperiortemperatures.Double-panedglass,bytheway,alsoresultsincleanerandhottercombustionoverallsincelessheatistransferredandlostthroughthedoorglass.Moreheatissentthroughthefluesoftheheaterforlong-termstorage.Inaddition,manymasonryheatersincorporateanair-washsysteminwhichcombustionairisdirectedacrosstheinsideofthedoor,keepingitmostlyclean.Eventhebestglassdoorsmayneedsomecleaningonoccasion,however.This

ismorelikelytrueduringthebreak-inorinitialwarmingperiodatthebeginningoftheseason.Sinceyoudon’tusemuchwoodduringthesetimesandthemassisnotyetwarm,sootcanaccumulateonjustabouteverythingintheheater,includingtheglassofthedoor.Oncetheheaterisuptotemperature,thisshouldnotoccurifyou’reusingtheproperamountofdrywoodateachfiring,unless,ofcourse,alogdoesfallagainsttheglass.Ingeneral,therearethreetypesofmaterialthatmayneedtobecleanedoff

masonryheaterdoorglass:ash,soot,andhardenedminerals.Thefirstofthese,simplefineash,isveryeasilyremovedwithjustawetpapertowelorothersoftdampcloth.Iftheglassisquitehot,itisbesttowaitforittocoolbeforewipingwithsomethingwet.However,theinteriorglasswillalmostalwaysbewarmtohot,soitmakessensetowipetheglasswithhotwatertoavoidsubjectingitto

thethermalshockofcoldwateragainsthotglass.Ashwilleasilyberemovedandtheglassshouldbedried,ifneeded,withasoftdrytowel.Blacksootandlightcoatingsofbrowncreosote(thatcancondenseonglassif

wetwoodwasburned)canbothbecleanedfromglasswithalittlemoreelbowgrease,twowetclothsortowels,onedrycloth,andsomewhiteashfromthefirebox.Asmentionedpreviously,ashmixedwithwatermakesaharshalkalinesubstancecalledlye,thebasisforsoap.Awetragdippedinashwilleffectivelycleansootandlightcreosoteoffglassjustaspowderedcleanserisusedonakitchencountertopstain.Itisbesttowearrubberglovesforthiscleaningoperation,thoughthisisn’tabsolutelynecessaryifyouavoidthewetashontheclothandwashyourhandsimmediatelyaftercleaning.

FIGURE12.6.Thefineashandsmallamountofsootaccumulatedonthisdooroveratwo-weekperiod.Anairwashkeepsitmostlyclean.Theglasscanbeeasilycleanedwithawetclothdippedinash.

Theash/lye“soap”willcutthroughthedepositsquicklyifyouuseacircularscrubbingmotion.Onceallthesoothasbeentherebyloosened,useasecondclean,dampclothtorinseandathirddrytoweltodryandpolishtheglassuntilitisperfectlyclearagain.Mineraldepositsarealittlemoredifficulttoremoveandsoarebestaddressed

assoonasyounoticethem.Thesedepositscanoccurfromburningwoodthatistoowet;themineral-ladenwatercondensesonthecoolerglassandevaporates,leavingtheminerals.Itcanalsobepartiallyaresultoftheverycleaningdiscussedabove.Cleaningoftenusinghardwateronhotglasscanaidincreatingabuildupofminerals.Oneofthewaystorecognizethisproblemisiftheglassorsomepartofitjustlooksalittlehazy,butwhenitiswipedwithawetclothitlooksperfectlyclean.Theglassthendrieswiththesamehazyappearance.

Youcanfindcleanersforthismineralbuildupatfireplaceandbarbecuestores,butitisalsopossibletoremoveitwithwhitevinegarandsalt.Dipabarelydampclothinstraightvinegar,thenintosomecommontablesalt.Scrubtheproblemareathoroughlyuntilyou’veremovedalltheminerals.Thesalt,inthiscase,ismainlyservingasanabrasive,andmayormaynotbenecessary,dependingontheseverityofthebuildup.Ifthemineralaccumulationhasgoneonforalongtime,thiscanbeatime-consumingcleaningjob;thisiswhyit’sbesttocleanitassoonasitisnoticed.Oneownerwaitedyears,thinkingthemineralbuildupwasapermanentetchingintheglass.Ittookmorethananhourofscrubbingtorestoreclaritytotheglass.Fireviewingisajoytomostpeople.Keepingtheglassofamasonryheater

cleanandclearisasimpletaskthatcanbeaccomplishedinjustafewminuteseithereverydayoratleastonceperweek.Ifitisnotdoneasregularmaintenance,itwilltakelonger.Likeanyotherhomemaintenancetask,alittlebitdoneregularlyreapsthemostrewardfortheleasttimespent.

MasonryHeaterBathAstructureofmasonrymaterialsisnearlyindestructibleinthehomeenvironment.Itwill,however,collectdust,cobwebs,andothernormalhouseholddirtand,likehomefurnishings,shouldbecleanedandregularlymaintainedforbestappearanceandenjoyment.Asdiscussedinchapter6,thechoiceofmaterialsusedforaheatershouldincludeconsiderationoftheeaseofmaintenance.Thoughaweeklyquickcleaningisrecommended,adeepercleaningshouldonlybenecessaryonceperyearwhentheheaterisnotbeingused.Themethodofcleaningdiffersdependingonthesurfacematerials.Forthoseheaterswithverysmoothorsemi-smoothsurfaceslikepolishedor

honedstone,kacheln(tiles),orplainstucco,thesurfacecanbedustedregularlywithafeatherdusterorsoftcloth.Ifadeepercleaningisrequired,allthesesurfacesrespondwelltowarm,soapywater.Typicaldishwashingsoapworksverywellforthispurpose.Tilesinparticulararevirtuallyimpossibletostainandwillalwayslookbrandnewifregularlywipedwithaclean,dampcloth.Polishedgraniteisaboutthesame,thoughsomegranitescanbestainedpermanently—notagoodthingforapermanentinstallationlikeamasonryheater.Honedsoapstonecannotbestainedpermanently.However,itwillacceptbodyoilsthatcanaccumulateonthesurface,makingthestonelookdarker.Again,warmsoapy

waterwillreadilycleansoapstone.Youcanalsopurchasecleanersmadespecificallyforstonesurfacesatahardwarestore,homecenter,orstonecountertopsupplier.

FIGURE12.7.Thissymmetricalstuccoheaterfeaturesmatchingsittingareasforenjoyingnotonlythefirebuttheensuingheataswell.Cushions,niches,andcompartmentsmakethewholestoveaninterestinggatheringpoint.PhotocourtesyofBiofire,Inc.

Brickandnatural(split)stoneveneersaremoreofachallengeforregularmaintenance.Sometimesafeatherdusterdepositsmoredirtonabricksurfacethanitremoves!Amorepracticalstrategyforbrickandroughstoneistobrushthesurfacewithafairlycoarsebristlebrush,allowingthedirttofallonthefloorwhereitcanbesweptorvacuumed.Italsoworkstouseavacuumwithabrush

attachmentonsucharoughsurface.Fordeepercleaning,theonlyrealoptionistowashtheheaterwithlotsofwaterandabrush.Obviously,thiscanonlybedoneifthefloorwillnotbeharmedbywaterorsomemethodisusedtokeepwateroffthefloor.Inadditiontothemasonrysurface,themetalpartslikedoorframesorsoot

doorsandashboxdoorswillneedsomeinfrequentcleaning.Aswiththeentireheater,quicklywipingthesepartseachweekwhentheashesareremovedorthedoorglassiscleanedisusuallysufficient,andaonce-per-yeargoodcleaningwithsoapywaterisrecommended.Thesepartscanbesimplywashedandrinsedandshouldbethoroughlydriedtopreventrusting.Ifthismaintenanceisdonerightattheendoftheheatingseason,it’salsoagoodideatolightlycoatthesesurfaceswithsomevegetableoil.Thisisaparticularlygoodideaforstovetopsandformasonryheatersinhomesthatmaybevacatedforthewholesummerseason(likeavacationhome).Thevegetableoilpreventsrustandwillburnawaywhentheheaterisusedagaininthefall.

MasonryHeaterCracksTheconstantexpansionandcontractionofamasonryheaterfromdailyheatingandsubsequentslowcoolingputsalotofstressonthedense,hardmasonrycomponents.Bricksandstonesjustdon’tflexlikearubberband.Thoughgreateffortsareoftenmadetoaccommodatesuchmovement(asshowninchapter8),itisalwayspossiblethatanymasonrypiececouldcrack.Thefireboxinparticulartakesarealbeatingandisthemostlikelyplaceforcrackstooccur.Buthairlinecracksontheoutsideofamasonryheaterarealwaysapossibility,too.Suchcracksarenotnecessarilyasignofpoorcraftsmanship.Inwell-built

heaters,infact,themorelikelyreasonforcrackingisthattherewasalreadyaninternalweaknessinthetile,brick,orstonethatcouldnotwithstandthepressuresofitsenvironment.Inthevastmajorityofcases,hairlinecracksintheexteriorarecompletelysuperficialtotheveneerandwillnotaffecttheoperationandenjoymentofthemasonryheater.

FIGURE12.8.Abrickmasonryheatercanbeeasilycleanedwiththebrushattachmentonavacuumcleaner.Thebrickanddark,oiledsoapstonecomplementtherusticinteriorofthisloghome.Noticethesmallseatwithwoodstoragebelowandanironrackattachedtothebricksideforhangingfireplaceimplements.PhotocourtesyofNewEnglandHearthandSoapstone.

Ifcrackshavedevelopedinternallyinamasonryheater,it’sbesttoarrangeforitsbuildertoassessthesituation.Inmanycases,nothingneedstobedone.If,however,thecrackissomethingthatisconstantlygrowing,itmayneedattentionsoonerratherthanlater.Reconstructionofsomeortheentirefireboxmaybenecessaryinthosethathavelargeandgrowingcracks.Anolderheaterthathasdeterioratingbricksmayneedsimilarattention.Generally,fireboxesshouldlastdecadeswithoutneedingserviceifproperlybuiltandproperlyused.Iftheheaterhasjointsbetweenstonesorbricksontheveneerthatkeep

openinglarger,thenclosingastheheaterisusedandcooled,itmaybethattheheaterwasnotbuiltwithmechanicalconnectionsanddependsonlyoncommonmortartobondelementstogether.Onesolutionistohaveamasonservicethesejointswhiletheheaterisstillinuseandhotasfollows:

1.Thejointsareheldattheirlargestwithawedge.

2.Oldmortarisremoved.

3.Newmortaristuckedintotheopenedcracks.

4.Theheaterisallowedtocoolcompletely.

5.Thewedgesareremovedandanyholescreatedbythempatched.

Forsimilaropeningandclosingjointsbetweenlargestonesofabenchorotherhorizontalsurface,aworkingsolutionistouseaflexiblesiliconecaulkinthejointsothejointcanfreelymove.Thecaulkwillmovewiththestone.Ifyoucan’tfindsuchacaulkofacolorcomplementarytothestonework,sometimesyoucancarefullymixclearorcoloredcaulkwithdustfromcuttingthestonetomakeacaulkthatprettywellmatches.MasonryheatersbuiltinNorthAmerica,ifbuiltbywell-trainedprofessionals,

alwayshaveaninnerlifeandanouterveneer.Smallcracksintheouterveneerarenotgenerallyofconcern,thoughitneverhurtstocheckwiththebuilderoranotherpersonfamiliarwithmasonryheaters.Likewise,mostheaterswillnotdevelopanycracksatallontheexterior,buteventheoriginalbuilderormanufacturerisnotlikelytoguaranteethatnonewilleveroccur.Thebestadviceinthisregardistoalwayshirethemostreputableandbest-trainedmasonsforamasonryheaterprojectformaximumdurabilityandlifelongenjoyment.

LivingwithaMasonryHeaterAmasonryheaterismorelikeapieceoffurniturethanitisafireplaceorwoodstove.(Someofmycustomershavesaidit’smorelikealivingbeing.)Youcanalwayssitonornearit,evenwhenitisatmaximumoutputofheat.Becauseitisonlyfueledonceortwiceadayduringtheheatingseason,debrisfromfirewoodcanberemovedandtheareakeptcleanthroughouttheday,incontrastwithopenfireplacesormetalwoodstovesthatneedregularfeeding.Sincethefireboxisalwayswarm,firesareeasilystartedandchimneydraftisimmediate.Yougetusedtothecycleofheatoutputfromtheheaterandcangaugehowmuchfueltousebasedonweatherpredictions.Bykeepinganeyeopenforopportunities,youcanoftengetfreefirewood

fromavarietyofsources,andatypicalfamilycansecureaone-yearsupplyofsplitfirewoodindrystorageinoneweekend.Regularcleaningandmaintenancetakelessthananhourperweek.Morethoroughcleaningattheendoftheseasoncanusuallybedoneinlessthanhalfaday.Heatingwithamasonryheaterrequiresyoutothinkaheadandplanandpayattentiontothesurroundings,theweather,andthefutureneedsofthefamily.Thephysicaleffortrequiredisminimalconsideringthereturninenjoymentoffireviewing,gentleradiantheat,

theuseofaforeverrenewablefuel,andalltheotheradvantagesinherentinmasonryheaters.Livingwithamasonryheateriseasyanddelightful.Thereisnodoubtthat

securingyourownfuelandphysicallymaintainingheatinahometakessometimeandeffort.Butthereisnootherreliablewaytoheatlivingspacewithrenewablefuelthatdemandssolittleattentionandyetaddssomuchtothehealth,comfort,andwell-beingoftheinhabitantsatthesametimeitbeautifiestheinteriorofthehome.Mostsignificantly,amasonryheaterguaranteesthat,withminimaleffort,thereisactuallysomethinginthehousethatistrulywarm.Itisnotpossibletosnuggleupagainstthehotaircomingoutofthefurnaceregistersofahouse.It’scrazytothinkaboutsnugglingagainstawarmfloor.Ametalwoodstoveistoohottogetnear.Butyoucansnuggleupagainstalover—oramasonryheater.FIGURE12.9.Anheirloommasonryheaterwillprovidealifetimeofenjoyment.Thissoapstonecustom“Lohi”modelproducedbyTulikivihasbuilt-inshelvesandseating.Thepartialdomeshapeandcarvedfisharealwaysconversationpieces.CourtesyofWarmStoneFireplacesandDesigns;photocourtesyofImpactPhotography.

APPENDICES

AppendixA:Resources

AntiqueMasonryHeatersVintageElementsEuropeanFlooringandDesignElements216BrookfieldDriveGreenwood,SC29646864-344-0529www.vintageelements.com

AshVacuumsTheLoveLessAshCompany1285East650SouthPrice,UT84501800-568-3949435-637-5885www.lovelessash.com

CompressedSawdustFuelEco-energyFuelPOBox458679JohnsonLaneSouthShore,KY41175606-932-3117linda@eco-energyfuel.comwww.eco-energyfuel.com

Ecolog1081,rueIndustrielleC.P.4Mont-Joli,QuebecCanadaG5H3K8418-775-5370866-549-9428

info@ecologcanada.comwww.ecologcanada.com

O’HaraCorporation120TillsonRockland,ME04841207-594-4444info@gogreenwithoharas.comwww.gogreenwithoharas.com

GasketedAir-SupplyDampers

ArzelZoningTechnology,Inc.4801CommerceParkwayCleveland,OH44128800-611-8312216-831-6068www.arzelzoning.com

NewEnglandHearthandSoapstone,LLC127NorthStreetGoshen,CT06756860-491-3091www.rodzander.com

HandheldInfraredThermometersExtechInstrumentsCorporation285BearHillRoadWaltham,MA02451781-890-7440,ext.220www.extech.com

InstrumartPOBox10738LeroyRoadWilliston,VT05495800-884-4967802-863-0085www.instrumart.com

OmegaEngineering,Inc.POBox40471OmegaDriveStamford,CT06907203-359-7700www.omega.com

RaytekCorporation800-866-5478www.raytek.com

MasonryHeaterCompaniesFeatured(Chapter8)

Albie-CoreMaineWoodHeatCompany,Inc.254FatherRasleRoadNorridgewock,ME04957207-696-5442info@mainewoodheat.comwww.mainewoodheat.com

Biofire,USBiofire,Inc.3220MelbourneSaltLakeCity,UT84106801-486-0266biofire@aol.comwww.biofireinc.com

Kuznetsov’sStovesIgorKuznetsovwww.stove.ruDouble-bellorsystemoffreegasmovement.

Stovemaster20655ShawsCreekRoadCaledon,OntarioCanadaL7K1L7519-938-9166alex_stovemaster@yahoo.cawww.stovemaster.com

EnvirotechRadiantFireplacesandEnvirotechMasonryHeatersByEmpireMasonryHeaters245ReedRoadScottsville,NY14546585-889-2002jsteele@empiremasonryheaters.comwww.empiremasonryheaters.com

TheHeliosNewEnglandHearthandSoapstone,LLC127NorthStreetGoshen,CT06756

860-491-3091rod@rodzander.comwww.rodzander.com

CrossfireFireplaces249BridgeStreetWestPOBox121Campbellford,OntarioCanadaK0L1L0800-865-8784sheaff@trytel.netwww.crossfirefireplaces.com

TempCastEnviroheatPOBox940593409YongeStreetToronto,OntarioCanadaM4N3R1800-561-8594staywarm@tempcast.comwww.tempcast.com

TulikiviTulikiviUS,Inc.c/oDrayerandCompanyPC195RiverbendDrive,Suite3Charlottesville,VA229111-800-843-3473www.tulikivi.com

MasonryHeaterOrganizationsAllianceofMasonryHeaterandOvenProfessionals,Inc.www.masonryheaters.org

MasonryHeaterAssociationofNorthAmericawww.mha-net.org

MasonryHeaterWorkshopsandEducationThoughmanycraftsmenofferworkshopsfromtimetotime,theindividualsorgroupslistedherehavemadeaconcertedeffortoveryearstoregularlyhostandadvertisetraining.Thislistmaynotbeexhaustive,butrepresentsreputablesourcesofeducationandtraining.Alsosee“MasonryHeaterOrganizations,”above.KachelofenMasonryHeaterSchoolofCanada(KMSC)405Langille’sLakeRoadBlockhouse,NovaScotiaCanadaB0J1E0

902-624-9583www.kachelofenschool.comOffersacomprehensiveprogramintraditionalkachelofenandgrundofendesign,construction,andsales.

MaineWoodHeatCompany254FatherRasleRoadNorridgewock,ME04957207-696-5442info@mainewoodheat.comwww.mainewoodheat.comMaineWoodHeatCompanyhasbeenadvertisingandhostingworkshopsformorethan30years.

RelatedIndustryOrganizationsASTMInternationalPOBoxC700100BarrHarborDriveWestConshohocken,PA19428www.astm.org

ChimneySafetyInstituteofAmerica(CSIA)2155CommercialDrivePlainfield,IN46168317-837-5362www.csia.org

HearthPatioandBarbecueAssociation1901NorthMooreStreet,Suite600Arlington,VA22209703-522-0086www.hpba.org

InternationalCodeCouncil500NewJerseyAvenue,NW,6thFloorWashington,DC20001888-ICC-SAFE(422-7233)www.iccsafe.org

Kachelofenverband(TheAustrianStoveAssociation)Contact:ThomasSchiffertDassanowskyweg81220Wien+43125658850Fax+431256588520office@kachelofenverband.atwww.kachelofenverband.at

NationalFireplaceInstitute

1901NorthMooreStreet,Suite600Arlington,VA22209703-524-8030www.nficertified.org

WoodwaitersButler’sBuddy,Inc.423East10thStreetBerwick,PA18603888-441-9810570-759-0550www.butlersbuddy.com

W.B.FowlerIndustries,Inc.4665NicholRoadWaterville,QuebecCanada,J0B3H0800-290-8510819-562-8510www.woodwaiter.comwww.wbfowler.com

AppendixB:R-ValuesofCommonBuildingMaterials

AdaptedandselectedfromAmericanSocietyofHeating,Refridgerating,andAir-ConditioningEngineers,(ASHRAE),1993HandbookofFundamentalsandwithpermissionfromR.L.MartinandAssociates,Inc.,Windsor,CO

AppendixC:ElevationandOutsideDesignTemperaturesforVariousCities

AdaptedandreprintedfromtheCoolingandHeatingManual,U.S.DepartmentofHousingandUrbanDevelopmentOfficeofPolicyDevelopmentandResearch.

AppendixD:HeatingDegreeDaysofVariousCities

ReprintedwithpermissionoftheAmericanSocietyofHeating,Refrigerating,andAir-ConditioningEngineersfromthe1981ASHRAEHandbookofFundamentals.

ENDNOTES

Introduction:WhatIsaMasonryHeater?

1.ASTMInternational,E1602-03:StandardGuideforConstructionofSolidFuelBurningMasonryHeaters,2003.

1.TheHearthIstheReasonfortheHouse

1.ChristopherAlexander,etal.,APatternLanguage(NewYork:OxfordUniversityPress,1977),p.839.2.HPBAPressRelease,“NewDataShowIncreasingConsumerDemandforFireplaces,Stoves,Insertsand

OtherHearthProducts,”March7,2006.

2.ABriefHistoryofFireandHotRocksinNorthAmerica

1.JohannaSpyri,Heidi(NewYork:JulianMessner,1945),p.229.2.OliveBeaupréMiller,editor,OvertheHillofMyBookHouse(LakeBluff,IL:BookHousefor

Children,1965),pp.163,165.3.KateSeredy,TheGoodMaster(NewYork:VikingPress,1935),p.36.4.Miller,OvertheHill,p.163.5.CharlesNeider,editor,TheCompleteEssaysofMarkTwain(Cambridge,MA:DaCapoPress,1991),

pp.103–4,658–60.6.PeterClegg,NewLow-CostSourcesofEnergyfortheHome(Charlotte,VT:GardenWayPublishing,

1975).7.HeikkiHyytiainenandAlbertBardenIII,FinnishFireplaces:HeartoftheHome(Hanko,Finland:

BuildingBookLimited,1988),p.7.8.“RussianFireplace:DemonstrationsandWorkshop,”NewMexicoEnergyInstitute,UniversityofNew

Mexico,Albuquerque,1981.

3.ThermalComfort:TheVerticalRadiantAdvantage

1.JohnSiegenthaler,RadiantArchitecture:ABasicCourseinRadiantPanelHeatingSystemsforArchitectsandBuilders(Loveland,CO:TealInternationalCorporation,2002),p.3.

2.Ibid.3.BenedictFrederickRaberandFrancisWilliamsHutchinson,PanelHeatingandCoolingAnalysis(New

York:JohnWileyandSons,1947),p.10.

4.BenefitsofMasonryHeaters1.Ziehe,Helmut,interviewbyDebraLynnDadd(October2005).Thearticlestemmingfromthisinterview

istitled“AboutBaubiologie”byDebraLynnDaddandcanbefoundatwww.debralynndadd.com.

2.InstituteforBaubiologieandEcology(2008).http://buildingbiology.net/terms.php(accessedApril1,2010).

3.AntonSchneider,CorrespondenceCourseBaubiologie,translatedbyHelmutZiehe(Clearwater,FL:InternationalInstituteforBaubiologieandEcology,Inc.1988),p.31.

4.RobertO.Becker,TheBodyElectric:ElectromagnetismandtheFoundationofLife(NewYork:WilliamMorrow,1985),p.284.

5.USCongress,OfficeofTechnologyAssessment,BiologicalEffectsofPowerFrequencyElectric&MagneticFields.BackgroundPaper,OTA-BP-E-53.(Washington,DC:USGovernmentPrintingOffice,May1989).

6.JohnR.HallJr.,“HomeFiresInvolvingHeatingEquipment,”NationalFireProtectionAssociation,January2010,p.i.

7.Ibid.,p.ix.

7.HeatingRequirementsoftheHouse

1.YoucanfindmoreinformationaboutsolargaininbookssuchasEdwardMazria’sThePassiveSolarEnergyBookaswellasJamesKachadorian’sThePassiveSolarHouse.Completeinformationisinthebibliography.

8.TheInnerLife—CoresandFlues

1.HenryFord,MyLifeandWork(GardenCity,NY:Doubleday,1922),p.73.2.Ibid.,p.72.

9.Codes,Clearances,Footers,andFoundations

1.www.kirche-suurhusen.de/turm/kirche.htm,(accessedNovember15,2009).

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ACKNOWLEDGMENTS

Ilovethisbook.HowcouldInot?Itwasameretwinkleinmyeyeaboutsixyearsago.FouryearsagoIstartedgettingreallyseriousaboutit,writingnotesanddisconnectedpages;twoyearsagoIwroteacoherentchapter.IhandedittoJudyLudwig,afriend,fellowhomeschooler,experiencededitor,andmasonryheaterowner.ShewasexcitedbutdelightfullyunforgivingandaskedmetocutthingsthatIknewcouldn’tpossiblybecutfromthetext.Thatchapterwasrewritten,revised,andreexaminedmoretimesthanIcaretoadmit.Itwasthatchapter,moldedunderherguidance,thatwassenttoChelseaGreenasoneoftwosamplechaptersthat,togetherwithmyformalproposal,landedthebookcontract.JudyhadlittletimeformybookwhenIwrotetheotherelevenchapters.YetIoftenfeltshewaslookingovermyshoulder.AsItypedeachchapter,Icouldhearhersaying,“Cut;thencutagain!”Forthis,JudyLudwiggetsspecialrecognitionandadmiration.InConnecticutlivesoneofthemosttalented,knowledgeable,anddevoted

heatermasonsaround.Whenitcomestomasonryheaters,RodZandermeansbusiness,andheknowsnocompromisetogivinghisbesttoaproject.Heexpectsthesamefromthosewhoworkwithhim.RodandElisabethZanderinvitedmeintotheirlivesandhomebrieflyasIwaswritingthelastcouplechapters.Ihadthehonorofhelpingtobuildthekachelofenthatappearsasfigure2.1.RodandElisabethZanderprovedtobethemostgenerousandhelpfulpairIencounteredinthisauthorshipodyssey.Thelittlesoapstoneheatershowcasedinchapter8,aswellasmuchoftheknowledgeimpartedthere,wouldnotexistwithoutRod’stutelageandgenerousmanner.ItwasRodwhoawakenedmetotheendlesspossibilitiesinherentinmasonryheaters.YetbeforeRodorJudyortheseedofanideaforabooktherewasAlbie

Barden.Likesomanyothers,I’veattendedAlbieBardenmasonryheaterworkshopsandprofitedfromhiskindnessandthree-plusdecadesofexperienceintheheaterworld.IthankAlbieforhisdeepcommitmenttomattersoftheheartandthehearth,andforwritingasplendidforeword.TomStroudgenerouslygaveofhishard-earnedknowledgetoshowmeand

otherstheoldGermanwaytodesignheaters.IthankTomforhoursonthephoneandathoroughreviewbeforethebookwasprinted.TimothySeaton,

CherylBarden,JoeParris,andJerryFrischandmanyunnamedothershaveallhelpedmeinonewayoranothertogetmewhereIamtoday.IthankStanSackettforhisloveofsoapstoneandhisfaithinmeoverthelastnineyearsorso.IthankRonPihl,JohnLaGamba,ErnstKiesling,EdithKiesling,Albie

Barden,ScottBarden,AmyClark,HeinzFlurer,TimothySeaton,JonathonSteele,WendellShort,ErichGundlach,TomTuer,MadySalyer,andRodZanderforputtingupwithmyfrequentandpersistentrequestsforphotographsforthisbook.JeremyJohnsonandTulikiviprovidedimmediatesupportandloadsoffinepictures.StefanHartung,MattFowleratW.B.FowlerIndustries,TimMotzattheToledoMuseumofArt,andStuartDavieswereimmediatelyresponsive,andtheirphotocontributionsinvaluable.ThanksalsotoJonSheaffatCrossfireFireplaces.SpecialmentiongoestoAlexChernovatStovemaster,whonotonlysentwonderfulphotos,buttookthetimetolearndetailsofwhatthisbookwasreallyaboutbeforeparticipating.Thepicture-fetchingprizegoestoLizAntonelliatYariFilmGroup,whosecuredaphotoofoneofthekachelofensfromthemovieTheIllusionistinrecord-breakingtime.IthankJulieCline,BarbaraFelton,LindsayandKathyGraham,PeggyandBenBrown,DavidandKerivanWingerden,andJimandDianeSchoenforeithersendingphotosorlettingmeinvadetheirhomesandescapewithimages.ParticularrecognitiongoestoJulieRustforlettingmerearrangeherlivingroomforphotosonChristmasEvewhileshebusily,andsingle-handedly,preparedhersonforaChristmaspageantbecauseherhusband,John,wasworkingyetmorelonghoursatthehospital.MarenLeylaCookenotonlytookfantasticphotosofherbeautifulsandstoneheatercreation,butalsotookthetimetowriteherowntestimonial.(Sorry,thecoverdoesn’thaveyourheater—orthegirls!Itried!)Thisbookcouldneverhavehappenedwithoutthemanypeoplewhohaveentrustedmewiththeirprojects.Thepicturesprovidedmakethisbookveryspecial;Iamdeeplyindebtedforallthehelpandcooperationwithimages.Thosewhoknowmethinkofmeasamanoffewwords,aprettyquietguy.

ButifI’mhandedapen(orlaptop),Icanwriteandwriteandwrite.Iwouldnotbepublishedtoday,however,ifnotforthewisdomandguidanceofElizabethLyon,afellownativeofnorthwestOhio,whosebookgavemethetoolsandlastshoveIneededtomakeithappen.BlessingstoMs.Lyon.Ofcourse,thewholestaffatChelseaGreenhasbeenfantastic.Iespecially

appreciatetheeffortsofCannonLabriewho,likeJudyLudwigbeforehim,artfullyblendedpraiseforthebookwiththeknowledgeofwhat’ssuperfluous.

ThankstoJoni,Makenna,andPati.IwillneverforgetMarcRoss,ProfessorEmeritusinthephysicsdepartmentat

theUniversityofMichigan.Inhiscollegeoffice,crammedwithbooksaboutthermodynamicsandefficiency,Marcpatientlyspentamorningdiscussingsecond-lawefficiency,combustion,andheatpumpswithmeasifIwerehisacademicequal.Thankyou,Marc.Finally,Igivemywarmestanddeepestappreciation,admiration,andloveto

mywife,Nancy,whotoldmetotreatwritingthisbooklikeafull-timejob(whichitwasanyway).OverandovershetoldmeshewantedthebookdonebeforeChristmas2009soitwouldn’ttarnishourholidays.Yetshesorted,read,andeditedrightbesidemeaswepreparedtosendthemanuscriptonDecember30.Iamhumbled,eternallygrateful,andtrulyblessedwithherlove,devotion,andconfidenceinme.

AbouttheAuthor

KENMATESZfirstlearnedaboutmasonryheatersintheearly1980s,builthisfirstoneintheearly1990s,andopenedtheMasonryHeaterStore,LLC,aftertheturnofthenewcentury.Matesz’sfirstsoloheaterprojectin1994,aFinnish-styleheaterinhisownhome,gavehisfamilyheating-energyindependence.Now,withhisnewbook,MasonryHeaters,hehopestoshowmanyothershowtheycanachievethesamefreedomandabetterstandardoflivingusingthissimplebutelegantwayofheating.HeliveswithhisfamilyinSwanton,Ohio.

AbouttheForewordAuthorALBIEBARDENisthefounderofMaineWoodHeatCompany.Hehasbeendesigningandbuildingmasonryheatersformorethanthirtyyears.

ChelseaGreenPublishingiscommittedtopreservingancientforestsandnaturalresources.Weelectedtoprintthistitleon10-percentpostconsumerrecycledpaper,processedchlorine-free.Asaresult,forthisprinting,wehavesaved:21Trees(40'talland6-8"diameter)9,621GallonsofWastewater7millionBTUsTotalEnergy584PoundsofSolidWaste1,998PoundsofGreenhouseGases

ChelseaGreenPublishingmadethispaperchoicebecauseweareamemberoftheGreenPressInitiative,anonprofitprogramdedicatedtosupportingauthors,publishers,andsuppliersintheireffortstoreducetheiruseoffiberobtainedfromendangeredforests.Formoreinformation,visitwww.greenpressinitiative.org.

EnvironmentalimpactestimatesweremadeusingtheEnvironmentalDefensePaperCalculator.Formoreinformationvisit:www.papercalculator.org.

thepoliticsandpracticeofsustainableliving

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thepoliticsandpracticeofsustainableliving

CHELSEAGREENPUBLISHING

ChelseaGreenPublishingseesbooksastoolsforeffectingculturalchangeandseekstoempowercitizenstoparticipateinreclaimingourglobalcommonsandbecomeitsimpassionedstewards.IfyouenjoyedMasonryHeaters,please

considertheseothergreatbooksrelatedtogreenbuildingandrenewableenergy.

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