heating solutions

Heating Solutions

Technical Advisory Service Tel: 0870 4435551 Fax: 0870 4435552 E-mail: info@hepworthterracotta.co.uk Section 2a Page 1

Fireplaces, Chimneys, Flues and TerminalsIntroduction

Burning solid fuel, gas and oil produces a number of corrosive orpotentially corrosive products such as chlorine compounds, sulphurdioxide and oxides of nitrogen. This is especially so if the gases mixwith moisture from condensation or rain to form an acidic flueenvironment. In addition, the combustion products from anyhydrocarbon fuel can contain the poisonous gas carbon monoxide.

To ensure the long-term durability,structural integrity and properfunctioning of a chimney, the internalcomponents used to build the chimneymust therefore withstand the effects ofcorrosive combustion products andprevent rainwater penetration. Thecomponents must also be impervious tothese poisonous gases so that they aresafely vented to the outside of a buildingand do not pass into habitable spaces.

In addition, the external componentsof a chimney or flue must not onlyresist the assault of acids and hightemperatures but also resist the effectsof weather and atmospheric pollution.To ensure the correct choice of flueterminal is made, local wind conditionsshould be assessed to see if strongdowndraughts will affect the efficientdispersal of flue gases.

To ensure the safe and efficientperformance, and structural integrity,of heating systems with fluedappliances and open fires, BuildingRegulations Approved Document Jstates that adequate provision must bemade for the following:

■ A permanent air supply.

■ Unimpeded discharge of theproducts of combustion to theoutside air.

■ Protection of people from burns,and buildings from fire, whilst aheating system is in use.

■ A durable, permanent notice platedescribing the performance of thehearth, fireplace, flue and chimney,thus ensuring that the flue is correctlyused with an appropriate appliance

Hepworth fireplace components, flueliners, terminals and chimney pots aredesigned and manufactured to operate within these clearly defined parametersof safety, efficiency, fire resistance andstructural integrity.

This part of the ‘Heating Solutions’section, with frequent reference to theBuilding Regulations, outlines theessential methods of fireplace andchimney construction to ensure thesafe functioning of open fires, heatingappliances, flues and terminals.

The advice is based on heating systemsthat use:

■ Solid fuel, and oil openfires/heaters/appliances with a ratedheat output up to 50 kW.

■ Gas open fire decorative fuel-effect(DFE) appliance with a rated inputup to 50 kW.

■ Gas appliances with a heat input upto 70 kW.

■ Oil appliances with a heat output upto 45 kW.

The types of construction required fordifferent fuels and appliances are shownas overview illustrations in ‘TypicalApplications’ and discussed more fully in‘Design Considerations’.

The ability of terracotta as a material towithstand the onerous conditions thatexist in chimneys and flues is given inthe ‘Product Performance Data’ section.

Heating Solutions

Section 2a Page 2 Technical Advisory Service Tel: 0870 4435551 Fax: 0870 4435552 E-mail: info@hepworthterracotta.co.uk

Fireplaces, Chimneys, Flues and TerminalsTypical Application

Chimney stack

Saddle flashing

Terracotta ridge tile (Two Hole Crested)

Ridge board

Sarking felt

Lightweight insulating infill

Chimney breast

Superimposed quarry tile hearth

Constructional hearth

Milner Scored Fireback

Chimney pot or flue terminal e.g. Louvre Pot

Front flashing and apron

Weathered cement mortarflaunching

Projected brickwork corbelling

Lightweight insulating infill in void betweenflue liner and chimney stack

Roof tiles

Flue Liners jointed with Flue LinerJointing Compound Y108

Chimney stack

Fireplace Lintel 600(Y181 – front section)

Fireplace Lintel 600(Y182 – back section)

Flue Adaptor

Airbrick

Cavity Liner

Rafter

Decorative fireplacesurround

A fireplace opening up to 600mm wide

Heating Solutions

Chimney stack

Saddle flashing

Terracotta ridge tile

Ridge board

Sarking felt

Chimney breast

Rafter

Firebrick-linedfireplacerecess

Weathered cement mortar flaunching

Roof tiles

Chimney stack

Flue Adaptor

Airbrick

Cavity Liner

Corbel Unit Y110

Fireplace Lintel 1000Decorative fireplacesurround

A fireplace opening between 600mmand 800mm wide

Heating Solutions

Chimney stack

Saddle flashing

Ridge board

Sarking felt

Chimney breast

Rafter

Roof tiles

Chimney stack

Flue Adaptor

Airbrick

Cavity Liner

Corbel Unit Y110

Fireplace Lintel 1000

Corbel Unit Y111

A fireplace opening between 800mmand 1000mm wide

Heating Solutions

Fireplaces, Chimneys, Flues and TerminalsProduct Characteristics

Flue liners

Fireplace opening components

General description

A range of concrete components usedto form a fireplace opening and throat,and also to support a flue lining above.

Applications

The complete range of components(lintels, flue adaptors, firebacks, firebricks,throat restrictor and otty hood) provideseffective solutions for building all sizes ofdomestic, recessed fireplace openings.

Benefits

■ Components are suitable for newbuild and refurbishment projects.

■ Flexible combination of componentsoffers varied constructionopportunities.

■ Fully compatible with flue liner range.

Materials

Loadbearing lintels, corbel units and flueadaptors are made from reinforcedrefractory concrete.

Firebacks, throat restrictors and ottyhoods are made from refractory fireclay.

Firebricks are made from low aluminafireclay (32.5% alumina content).

Specification standards

Firebacks, lintels, corbel units and flueadaptors are manufactured to BS 1251:1987 ‘Specification for open-fireplacecomponents’.

Firebricks are manufactured to BS 1902:‘Methods of testing refractory materials’.

Regulations

Constructing an open recessed fireplacewith Hepworth Terracotta fireplacecomponents will meet the requirementsof The Building Regulations 2002,Approved Document J: Combustionappliances and fuel storage systems.

‘Design Considerations’ includesdetailed aspects of Building Regulationsrequirements.

Flue liners

General description

A range of terracotta components thatline a flue way and protect the enclosingbrickwork/masonry from the corrosiveaction of flue gases and moisture.

Applications

Terracotta flue liners are designed toserve all types of open coal fire,decorative fuel effect gas fires or closedheating appliances fuelled by solid fuel,gas or oil.

Benefits

■ Manufactured to tight tolerances for easy and accurate assembly.

■ Suitable for conveying flue gasesfrom all types of heating appliance.

■ Smooth internal surfaces resist thebuild-up of soot and tar deposits.

■ A range of internal flue sizes suitablefor conveying flue gases from mosttypes of heating appliance.

Materials

The flue liners are made from terracottaformed from specially selected clays forlong-term in-use stability and durability.

The flue liners are tested to BS EN1457: 1999 ‘Clay/ceramic flue liners –Requirements and test methods’ tosatisfy compressive strength criteria,resistance to acid attack and airpermeability, and ability to withstandhigh temperatures.

Regulations

Hepworth Terracotta flue liners meet the requirements of The BuildingRegulations 2002, Approved DocumentJ: Combustion appliances and fuelstorage systems.

Heating Solutions

Chimney pots

Flue liner terminals

General description

A range of terracotta components usedto terminate a flue lining above roof level.

Applications

Terracotta flue liner terminals are usedas an alternative to chimney pots whereaesthetic considerations or local traditionare not important.

Benefits

■ Terracotta flue liner terminals areresistant to frost and the freeze/thaw cycle.

■ Chemically treated to preventefflorescence.

■ Available in red, buff and blue/black.

■ Smooth internal surfaces resist thebuild-up of soot and tar deposits.

■ A range of internal sizes suitable for conveying flue gases from mosttypes of heating appliance.

Materials

The flue liner terminals are made of terracotta formed from specially selected clays for long-term in-usestability and durability.

The flue liners terminals are tested to BS 1181: 1999 ‘Specification for clayflue linings and flue terminals’ to satisfycompressive strength criteria, resistanceto acid attack and air permeability, andability to withstand high temperatures.

Regulations

Hepworth Terracotta flue liner terminalsmeet the requirements of The BuildingRegulations 2002, Approved DocumentJ: Combustion appliances and fuelstorage systems.

Chimney pots

General description

A range of terracotta components thatperform the same function as flue linerterminals but offer a wider aestheticchoice and more flexible response tolocal airflow conditions. (See note below)

Applications

Terracotta chimney pots are usedwhere the termination of a chimney is subject to aesthetic considerationsor to local tradition. (See note below)

Benefits

■ A wide variety of designs to suitmost aesthetic requirements.

■ Colours will not fade.

■ Anti-downdraught types are alsoavailable to counter locally difficultwind conditions, although expertadvice should always be taken.

■ Terracotta chimney pots are resistant to frost and the freeze/thaw cycle.

Materials

Chimney pots are made of terracottaformed from specially selected clays forlong-term in-use stability and durability.

The chimney pots are tested to BS 1181: 1999 ‘Specification for clayflue linings and flue terminals’ to satisfycompressive strength criteria, resistanceto acid attack and air permeability, andability to withstand high temperatures.

Regulations

Hepworth Terracotta chimney pots meetthe requirements of The BuildingRegulations 2002, Approved DocumentJ: Combustion appliances and fuelstorage systems.

Note: See ‘Gas Flue Block System’ for adescription of Gas Flue Terminals

Heating Solutions

Purpose-made chimney potsGeneral description

A technical service is available thatenables any design to be made to order.

Applications

Purpose-made chimney pots are usedwhere the termination of a chimney issubject to aesthetic considerations or tolocal tradition.

Benefits

■ Enables a very flexible andappropriate response to be made tothe context of a building, whether fornew-build or refurbishment projects.

■ Terracotta purpose made chimneypots are resistant to frost and thefreeze/thaw cycle.

Materials

Purpose-made chimney pots are madeof terracotta formed from speciallyselected clays for long-term in-usestability and durability.

Specification Standard

The purpose-made chimney pots aretested to, and satisfy, BS 1181: 1989‘Specification for clay flue linings andflue terminals’. The tests covercompressive strength criteria, resistanceto acid attack and air permeability, andthe ability to withstand hightemperatures.

Regulations

Hepworth Terracotta chimney pots meetthe requirements of The BuildingRegulations 2002, Approved DocumentJ: Combustion appliances and fuelstorage systems.

Ventilation terminals

General description

A range of terracotta fittings used tocap off flues or chimneys that are nolonger in use. These terminals must bereplaced with appropriate flue terminalsor chimney pots when/if the flues orchimneys are brought back into use.

Applications

The terminals prevent rain penetrationand, used in conjunction with internalventilation grille(s), also provide through-ventilation to prevent condensation.

Benefits

■ An effective and simple method,requiring minimal alteration work,for maintaining the structuralintegrity of an un-used chimneyover an extended period.

■ Ventilation terminals are resistant to frost and the freeze/thaw cycle.

Materials

Ventilation terminals are made ofterracotta formed from specially selectedclays for long-term in-use stability anddurability.

Specification standard

The ventilation terminals are tested to,and satisfy, BS 1181: 1989‘Specification for clay flue linings andflue terminals’. The tests covercompressive strength criteria, resistanceto acid attack and air permeability.

Purpose-made chimney pots

Ventilation terminals

Heating Solutions

Fireplaces, Chimneys, Flues and TerminalsDesign Considerations:Introduction

General

Solid fuel

GasOil

Design Considerations is intended to provide architects, specifiersand builders with an understanding of how to design and constructcombustion installations for the safe and efficient performance ofsolid fuel, gas or oil heating systems.

Chimney design will vary for differenttypes of appliance and whether the fuelburned is solid fuel, gas or oil. There arealso regional variations in the buildingregulations and standards covering eacharea of the UK.

Design factors that need to beconsidered include:

■ Type of fuel

■ Type of heating appliance

■ Chimney location in a building

■ Chimney height

■ Roof pitch and openings

Throughout ‘Design Considerations’, the use of Hepworth products isunderpinned by the requirements ofApproved Document J of the BuildingRegulations 2002.

To aid the understanding of a complexsubject and to ensure an appropriateheating solution is achieved, ‘DesignConsiderations’ is divided into 4 sub-sections.

General requirements of heatingsystems (pages 9-13)

■ General air supply requirements toan appliance.

■ Free area measurement methods.

■ Permanent air vent locations

■ Chimney locations, offsets.

■ Flue sizes.

■ Height of chimney and chimneystack.

■ Roof pitch, openings and chimneyperformance.

■ Notice plate requirements.

Specific requirements of heatingsystems burning solid fuel (pages 14-23)

■ Permanent air supply requirements.

■ Hearths.

■ Fireplace recesses.

■ Flue sizes.

■ Wall thickness around flues.

■ Flue outlet positions and heights.

■ Flammable clearances.

Specific requirements of heatingsystems burning gas (pages 24-25)

■ Gas fire types.

■ Hearths.

■ Flue sizes.

■ Distance from roof windows.

Specific requirements of heatingsystems burning oil (pages 26-27)

■ Flue sizes.

Heating Solutions

Fireplaces, Chimneys, Flues and TerminalsDesign Considerations: General requirements of heating systems

Figure 1

Figure 2

Total free area of each air-vent type = a1 + a2 + a3 + a4 + a5 + a6 + a7 (mm2)(Note: The area height dimension is always measured at right angles to the slope of each vent slot/hole)

Well ventilated roof void space

Habitable space

Combustionappliance

Suspended floorWell ventilated floorvoid space

Permanent air-vent locations

Measuring free area of permanent air-vents (showing two alternatively configured vents)

Areas of air-vent type 1

Areas of air-vent type 2

General air supply requirements to an applianceThe provision of a permanent air supplyto combustion appliances is crucial to:

a) Ensure the safe and efficient burningof solid fuel, oil or gas.

b) Ensure the products of burning areproperly drawn through flues andsafely discharged to the outside air.

It is dangerous to ignore thisessential requirement as set out in theBuilding Regulations 2002, ApprovedDocument J: Combustion appliancesand fuel storage systems. It is notsufficient to rely on air leakage arounddoors and windows, particularly with theneed to conform to increasinglystringent legislation for reducing heatloss and the consequent requirement fordouble glazing and draught proofing.

Free area measurement method for air-ventsTo ensure that the required free area ofa permanent air-vent is correctlymeasured refer to the method shownin Figure 1. See pages 14, 24 and 26for the correct amount of ventilationrequired for various types of heatingappliance and fuel use.

Permanent air-vent locationsPermanently open air-vents should belocated where they are unlikely tobecome blocked. Uncomfortably colddraughts can be avoided if the vents areplaced close to heating appliances ortake air from other internal spaces suchas hallways. Air-vents should also not beset within fire resisting walls (other thanexternal walls) thereby allowing thepassage of smoke in the event of a fire.In addition, to prevent dust particles orashes from being disturbed by draughts,air vents should not be located withinfireplace recesses or near hearths.

Refer to Figure 2 for the preferredlocations of permanent air vents tocombustion appliances.

Design Considerations: General requirements of heating systems

Heating Solutions

Fireplaces, Chimneys, Flues and Terminals

Flue sizesFlue size is a critical design feature and should always be at least equal to, and never less than, the size of theflue outlet on an appliance likely to beinstalled. Where an offset is included in a flue then the flue size should beincreased by 25mm on each of thestatutory minimum dimensions (i.e.diameter or the sides of a square).Guidance on the minimum flue sizes to be used with each type of fuel andheating appliance is given in the relevant‘Design Considerations’ sections.

Figure 4

Figure 3

Figure 5

Angle should not be morethan 45º

Bend 1

Bend 2

Offset calculation table 1

Measuring offsets (read with table 1 below)

Preferred chimney location

Other chimney locations (less favourable for optimum all-round performance)

The tables apply to both round and square flue liners

Offset calculation table 2

Chimney locations and offsetsThe best position for a chimney is in the centre of the building. Maximumadvantage can then be gained from its heat storage and ventilationcharacteristics. Refer to Figure 3.

The most effective chimney is one that is straight and terminates with astraight-sided, hooded pot. Contrary to popular belief, an offset does nothave any anti-downdraught effect nordoes it prevent rain penetration. It does,however, encourage the build-up of soot that may lead to chimney fires andrestricts the evacuation of combustionproducts. An offset is therefore notrecommended unless it is unavoidable – such as another fireplace directlyabove, or the stack must penetrate theroof in a particular location for structuralor visual reasons.

Refer to Figure 4 for measuring offsetswhere used. In addition, refer to theflue offset calculation tables 1 and 2,and also to ‘Flue sizes’ below for theeffect of offsets on flue size.

Other locations that may offer scope fora straight chimney (but do not maximisethe potential gains from heat storage)are shown in Figure 5.

For the relationship of a fireplaceopening to an external or internal wallsee ‘Specific requirements of heatingsystems burning solid fuel’.

Offset provided by straightswhen used with bends (Refer to figure 4)Angle Length Offset Verticalof unit of straight A height B

180 66 159

22.5º300 112 270450 169 401600 227 540180 86 150

30º300 146 244450 221 377600 296 507180 105 137

37.5º300 178 232450 270 344600 361 463

Total offset provided by use of 2 bends only, without straightsAngle Total Combinedof unit offset height22.5º 81 41430º 144 54337.5º 223 664

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Figure 6

Figure 7

Level of highest point of intersection

4m mineffectiveflue height

Appliancewith directconnection

Appliance with flue pipeconnection

Open fire (and DFE) with throat and gather

unit connection

Chimney stack height

Minimum chimney height

Height of chimney and chimney stackTo ensure a flue efficiently drawscombustion gases away from anappliance, a general rule is for theminimum chimney height to be not less than 4 metres vertically from theappliance outlet (or top of fireplaceopening) to the top of the flueenclosure (but not the chimney pot or flue terminal). See Figure 6.

To ensure structural stability ismaintained, the height (H) of thechimney stack above its intersectionwith the roof should not exceed 4.5times its minimum horizontal width (W).See Figure 7.

Design Considerations: General requirements of heating systems

Heating Solutions

Figure 8

Figure 9

Figure 10

Wind direction

Low pressure suction zone

High pressure

Roof pitch over 30º

Roof pitch over 30º – effect of openings in the leeward (suction) zone

Preferred location

Roof pitch below 30º

Roof pitch, openings and chimney performanceWhen a building interrupts wind flow,high-pressure zones and low-pressure(suction) zones are created. These will affect the efficiency with which achimney discharges combustion gases.

For a high-pitched roof (>30º), thepressure on the windward slope isgreater than that on the leeward side. A flue outlet located in this high-pressurezone may cause fume emission from anappliance it serves unless the outlet israised above the high-pressure zone orplaced on the leeward slope in thesuction zone. See Figure 8.

In addition, if the room in which theflue originates has apertures that openinto the suction zone, the possibility ofappliance fume emission will beincreased. Therefore, for a high-pitched roof it is desirable that achimney placed on the windwardslope is located as near to the ridge aspossible where a reduced air pressureexists. See Figure 9.

For a low-pitched (<30º) or flat roof, the positioning of the chimney is not so critical and the wind effect may belargely ignored. Refer to Figure 10.

Despite these precautions, the windpressure and suction patterns formedby the building may affect chimneyperformance adversely, depending onthe proximity of other openings in thebuilding and of adjacent structures.

Building Regulation requirements for thelocations and heights of flue outletsare shown in the following figures:

■ Figure 13, page 22, for solid fuelappliances

■ Figure 3, page 25, for gasappliances

■ Figure 2, page 27, for oilappliances

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IMPORTANT SAFETY INFORMATIONThis label must not be removed or covered

Property address 123 West StreetLower Wyevale

The hearth and chimney installed in the living roomare suitable for decorative fuel effect gas fireChimney liner terracotta round straight ,

210mm diameterSuitable for condensing appliance noInstalled on (date)

(Essential information is listed above)

Other information (optional) Designation of stainless steel liner stated by manufacturer to be ................

Including for example, installer’s name, product trade names, installation and maintenanceadvice, European chimney product designations, warnings on the performance limitationsof imitation elements e.g. false hearths.

(Optional additional information is listed below)

Figure 11

Example notice plate for hearths and flues

Notice plate requirementsEach chimney and flue system installedmust have a robust, indelibly marked,permanent notice describing theperformance capabilities of the hearth,fireplace, flue and/or chimney. Thenotice ensures that the installation of aparticular heating appliance will becompatible with these elements.

The notice plate should contain thefollowing information:

■ Location of hearth and fireplace, orthe location of the beginning of theflue

■ Flue category and compatiblegeneric types of heating appliances

■ Type and size of flue and themanufacturer’s name

■ Installation date.

The notice could be securely fixed andlocated in any of the following positionsso that it is unobtrusive yet clearly seen:

■ Next to electric consumer unit

■ Next to water supply stopcock

■ Next to the chimney or hearthdescribed on the notice.

See Figure 11 for an example of atypical notice plate for hearths and flues,indicating essential and optionaladditional information.

Heating Solutions

Fireplaces, Chimneys, Flues and TerminalsDesign Considerations: Specific requirements of heating systems burning solid fuel

Notes:

1. Divide the area given in mm2 by 100 to find the corresponding area in cm2

2. For simple open fires as depicted in Figure 6. the requirement can be met with room ventilatIon areas as follows:

Nominal fire size (fireplace opening size) 500mm 450mm 400mm 350mm

Total free area of permanently open air vents 20,500mm2 18,500mm2 16,500mm2 14,500mm2

3. Example: an appliance with a flue draught stabiliser and a rated output of 7 kW would require a free area of: (5 x 300) + (2 x 850) = 3200mm2

Air supply to solid fuel appliances

Permanent air supply requirementsThe table below indicates the type andamount of ventilation required for openfires and various types of solid fuelburning appliance.

Type of appliance Type and amount of ventilation (1)

Open appliance, such as an open fire with no Permanently open air vent(s) with a total free area of at leastthroat, e.g. a fire under a canopy. 50% of the cross sectional area of the flue.

Open appliance, such as an open fire with a throat. Permanently open air vent(s) with a total free area of at least 50% of the throat opening area. (2)

Open appliance, such as a stove, cooker or boiler, with Permanently open air vent(s) as below: (3)a flue draught stabiliser.

Total free areaFirst 5kW of appliance rated output 300mm2/kWBalance of rated output 850mm2/kW

Other appliance, such as a stove, cooker or boiler, with A Permanent air entry opening or openings with a total no flue draught stabiliser. free area of at least 550mm2 per kW of appliance rated output

above 5kW.

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Figure 1

Not less than 150mm

Figure 2

b) Plan of freestanding constructional hearth

a) Plan of constructional hearth with fireplace recess (See also Figure 5, page 17)

Front of hearth not lessthan 500mm from jambof fireplace recess

Not less than 840mm

Not less than250mm

Combustible material

Top surface of hearth

Not less than 125mm

Airspace not less than 50mm

Not less than 500mm

Section through constructional hearth with fireplace recess

Constructional hearths A solid fuel appliance or open fire mustbe safely isolated from people andcombustible parts of the building fabric.A common method is to provide aconstructional hearth for the applianceto stand on, such as a substantial, non-combustible base that is part ofthe building structure. Refer to Figures1 and 2 showing the minimum planand section requirements for aconstructional hearth.

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Figure 3

Figure 4

Perimeter of superimposedhearth must be clearly

marked

Not less than 150mm

Heatingappliance

Opening to firebed

Perimeter of superimposedhearth must be clearly marked

Notes for Figure 3*Dimension A to be not less than:1) 225mm for a closed appliance2) 300mm for an open appliance or a closed appliance

that can be used with its front open

** See Figure 7, page 18, for wall requirements closer than150mm

b) Plan of freestanding superimposed hearth

a) Plan of superimposed hearth/fireplace recess

Wall**

150mm +

Constructional hearthoutline

Constructional hearth outline

Not less than 150mm

b) Section: Appliance standing directly on constructional hearth

Not less than 150mm

c) Section: Appliance in a fireplace recess with superimposed hearth

a) Section: Appliance that does not cause hearth temperature to exceed 100ºC

Heatingappliance

Combustiblematerial

For dimension see Figure 1 (page 15)

For dimensions see Figure 3 (this page)

Change in level to indicatesafe perimeter

Non-combustible material

At least 12mm

Superimposedhearth

Not lessthan 150mm

Not morethan 150mm

Superimposed decorativehearthsAs well as standing an appliancedirectly on the constructional hearth(with combustible flooring kept at asafe distance), an appliance may alsostand on a non-combustibledecorative hearth that has beensuperimposed on the constructionalhearth. Whichever method is adopted,a change of level is used to indicatethe safest distance that combustiblefloor finishes may be laid from anappliance. Refer to Figures 3 and 4 formethods of providing a hearth with asafe perimeter around an appliance.

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Figure 5

Figure 6

a) Solid wall recess

Not less than200mm

Not less than 200mm

Not less than100mm

Each masonryleaf not less than200mm

b) Cavity wall recess

c) Internal wall recess (in same dwelling)

a) Elevation showing Hepworthfireplace opening components only

b) Section showing Hepworth fireplace openingcomponents built in

Flue Liners

Fireplace Lintel

Flue Adaptor

Fireback

c) Plan showing Hepworth fireplace opening components built in

Fireback

Flue Liners over

Decorative hearth

Fireplace recess

Insulating infill

Enclosing masonry

Insulating infill

Throat 110 ±10mm

Sand/cement benching

Insulating infill

Constructional hearth outline

Fireplace recessIn addition to the non-combustibleconstructional hearth, a non-combustible surround such as afireplace recess must also be providedto protect the building fabric from theheating appliance or open fire. Figure 5shows the minimum plan requirementsfor a fireplace recess, whilst Figure 6(using a 600mm max wide fireplace asan example) shows a plan and sectionthrough a fireplace recess indicating theHepworth complementary fire-resistingcomponents required. The throat profileenables the flue to function efficiently.

For various methods of formingfireplaces with different opening sizes,see ‘Installation Details’, pages 28-33.

Design Considerations: Specific requirements of heating systems burning solid fuel

Heating Solutions

Solid masonry or concrete wall

Heatingappliance

Not less than 150mm

For dimensions see Figure 3, page 16

For thickness (T) of wall,see table below

Figure 7 (Read with table below)

Walls adjacent to hearths – plan

For height (H) of wall above appliance/hearth,see table below

Not less than 150mm

Superimposed hearth

Dimensional requirements for walls adjacent to hearths

Walls adjacent to hearthsIf a fireplace recess is not used toenclose a heating appliance, otherwalls nearby must be capable ofprotecting the building from a potentialfire hazard. Figure 7 indicates the non-combustible elements and minimumsafe distances required.

Location of hearth or appliance Solid, non-combustible materialThickness (T) Height (H)

Where the hearth abuts a wall and the appliance is not more than 200mm at least 300mm above the appliance50mm from the wall and 1.2m above the hearth

Where the hearth abuts a wall and the appliance is more than 75mm at least 300mm above the appliance50mm but not more than 300mm from the wall and 1.2m above the hearth

Where the hearth does not abut a wall and is no more than 75mm at least 1.2m above the hearth150mm from the wall (See note below)

*Note: There is no requirement for protection of the wall where W is more than 150mm

Establishing the correct internal flue sizefor heating applications with a rated out-put of up to 45 kW

Heating Solutions

Area of fireplace opening (A x B)mm2

437,500 500,000 562,500375,000312,500250,000

31,250

37,500

43,750

50,000

56,250

62,500

68,750

75,000

81,250

87,500

93,750

Bungalow

Two storey

Graphical method procedure

The required terracotta flue liner can be sized byreading off the cross-sectional flue area valuesfrom the graph above (after first establishing thefireplace opening area A x B) and finding theequivalent internal flue size from the table.

The selection from the table should be to the nextstandard size corresponding to C.

Flue sizesFor a masonry chimney built with afireplace recess into which an open fire,room heater or stove may be fitted, aflue size of 225mm diameter or 200mmsquare is recommended. BuildingRegulations require an absoluteminimum diameter for circular flues of200mm. These flue sizes are alsosuitable for closed appliances and foropen fires with a front opening up to500mm wide by 550mm high.

Similarly, a chimney pot should havethe same cross-sectional area as theflue and not less than 200mm diameteror 185mm square.

For larger open fires or for openableroom heaters, the recommended cross-sectional area of the flue should be atleast 15% of the free unobstructed areaof the fireplace opening.

The flue sizing guide, using either thegraphical method (opposite) orformula method (page 20), will ensurethe correct size of Hepworth flue lineris used with a particular fireplaceopening area and chimney height. Thesizing guide methods are suitable forheating applications with a rated outputof up to 46 kW.

For a freestanding boiler, cooker, or acoal burning stove, not housed in afireplace recess, the minimum flue sizerecommended is 150mm diameter (orsquare equivalent) or according to theappliance manufacturer’s instructions.In practice, a minimum flue diameter of150mm is always recommended andunder no circumstances should aflue size be less than 125mmdiameter.

Internal flue size Area of flue (C)(mm) (mm2)

Circular

210 34,640

225 39,766

250 49,094

300 70,695

Square

185 34,255

200 40,000

225 50,625

250 62,500

300 90,000

Flue sizing guide:Graphical method

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Flue sizing guide:Formula method

The Building Regulations 2002,Approved Document J, specifies that forfireplaces with openings larger than500mm x 550mm the correct flue linersize is based on a cross sectional areaequal to 15% of the total face area ofthe fireplace opening.

Specialist advice should be sought whenproposing to construct flues having anarea of: a) more than 15% of the total face area

of the fireplace openingb) more than 120,000mm2

For offset restrictions to all fluesirrespective of fireplace opening sizeand type of fuel used, refer to page 10.

See page 34 for the correct procedurefor building a lined chimney flue.

See pages 28 to 33 for for the correctprocedures for building various sizes offireplace opening. A

Table 1B

Table 1A

Hepworth Hepworth DescriptionFlue Size Class A1 Specification

(mm) Flue Liners* (mm)YC10C1 300 straightYC11C1 450 straight

125 Round YC12C1 600 straight(int dia) YC13C1 22.5º bend

YC14C1 30º bendYC16C1 300 straightYC17C1 450 straight

150 Round YC18C1 600 straight(int dia) YC19C1 22.5º bend

YC20C1 30º bendYD10C1 180 straightYD11C1 300 straightYD12C1 450 straight

185 Round YD13C1 600 straight(int dia) YD14C1 22.5º bend

YD15C1 30º bendYD16C1 37.5º bendYG10C1 180 straightYG11C1 300 straightYG12C1 450 straight

185 Square YG13C1 600 straightYG14C1 22.5º bendYG15C1 30º bendYG16C1 37.5º bendYD17C1 180 straightYD18C1 300 straightYD19C1 450 straight

210 Round YD20C1 600 straight(int dia) YD21C1 22.5º bend

YD22C1 30º bendYH10C1 180 straightYH11C1 300 straightYH12C1 450 straight

200 Square YH13C1 600 straightYH14C1 22.5º bendYH15C1 30º bendYE10C1 180 straightYE11C1 300 straightYE12C1 450 straight

225 Round YE13C1 600 straight(int dia) YE14C1 22.5º bend

YE15C1 30º bendYE16C1 37.5º bendYH17C1 180 straightYH18C1 300 straightYH19C1 450 straight

225 Square YH20C1 600 straightYH21C1 22.5º bendYH22C1 30º bendYH23C1 37.5º bendYF10C1 180 straight

250 Round YF11C1 300 straight(int dia) YF12C1 22.5º bend

YF13C1 30º bendYJ10C1 180 straightYJ11C1 300 straight

250 Square YJ12C1 22.5º bendYJ13C1 30º bendYF15C1 180 straightYF16C1 300 straight

300 Round YF17C1 22.5º bend(int dia) YF18C1 30º bend

YF19C1 37.5º bendYJ15C1 180 straightYJ16C1 300 straight

300 Square YJ17C1 22.5º bendYJ18C1 30º bend

Flue Size:Nominal cross Recommended Technicalsectional area flue size notes

(mm2) (mm)12260 125 Round (int dia) Suitable for closed oil/gas appliances only.

Not suitable for any solid fuel open fire or DFE gas fire17660 150 Round (int dia) Suitable for closed oil/gas appliances only.

Not suitable for any solid fuel open fire or DFE gas fire26870 185 Round (int dia) Meets the minimum flue requirement for use with a

DFE gas fire. Not suitable for use with a solid fuel open fire31600 185 Square Suitable for all multi-fuel applications34620 210 Round (int dia) Suitable for all multi-fuel applications37400 200 Square Suitable for all multi-fuel applications39740 225 Round (int dia) Suitable for all multi-fuel applications48000 225 Square Suitable for all multi-fuel applications49060 250 Round (int dia) Suitable for all multi-fuel applications59900 250 Square Suitable for all multi-fuel applications70650 300 Round (int dia) Suitable for all multi-fuel applications87400 300 Square Suitable for all multi-fuel applications

Formula method procedure

The required terracotta flue liner can be sized byworking through the calculation procedurebelow to establish the cross-sectional flue areavalues and finding the equivalent internal fluesize from the selector tables.

The formula method is in 3 steps.

Step 1

Establish the fireplace opening area A(width) x B (height), then multiply by 15%.

A worked example:

A(550mm) x B(550mm) = 302,500mm2 (area offireplace opening)

302,500 x 15% = 45,375mm2 (recommendedflue size, i.e nominal cross sectional area)

Step 2

Select the correct flue size from Table 1A, usingthe nominal cross sectional area obtained inStep 1.

The selection from the table should be to thenext standard size up. This gives 225mm square.

Step 3

Select the correct Hepworth clay flue liner fromthe range shown in Table 1B.

A choice of different lengths and bends is available for each flue size.

Notes for Table 1B

Hepworth Flue Liners are manufactured to BS EN 1457: 1999

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Figure 8

Flue enclosure and separation

Figure 9

Separation distances from combustible material and a flue way

Figure 10

Figure 11

Figure 12

Inside

Outside

Dwelling

Combustible material on metal fixingor support

Metal fixing or supportThe following materials maybe set directly against amasonry chimney or fireplacerecess: Floorboards, skirting boards,dado rails, picture rails, mantel-piece, architraves

For other combustiblematerials:Where a masonry enclosureis less than 200mm theseparation distance shouldnot be less than 40mm

Not less than 50mm

Not less than 200mmLess than 200mm

Straight-sidedpot

Tapered pot

Precast concreteor stone capping

Flue linerextended

Flue liner

Cementmortar

flaunching

Cementmortar

flaunching

Flue liner

Chimney stack with concrete/stone capping

Extended flue liner

Chimney pot support

Flue liner

Wall thickness around fluesA flue in a chimney should be enclosedby, or separated from another flue by,solid non-combustible material not lessthan 100mm thick. In addition, minimumseparation distances should bemaintained between a flue way (A) andany combustible material, to ensure thedissipation of heat through the wallsfrom flues or fireplaces does not ignitethe material. See Figures 8 and 9.

Chimney pot or terminal supportThe pot or terminal should be built intothe chimney stack to give anembedment of not less than 125mm orone quarter of its length. This isparticularly important to ensure that thepot or terminal does not become asafety hazard during periods of highwinds. See Figure 10 for the installationof straight-sided and tapered pots or terminals.

Alternatively, a flue terminal may beformed by extending a Hepworth flueliner to project not less than 150mmabove the head of the chimney stack.See Figure 11.

The surface of the masonry throughwhich the flue projects above thechimney stack should be finished off bya weathered cement mortar flaunchingas shown in Figure 10 above.Alternatively, a precast concrete or stonecapping may be used. See Figure 12.

Where the flue serves a fireplace recess,the chimney pot or terminal should havethe same cross-sectional area as theflue and be not less than 200mmdiameter or 185mm square.

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Figure 13

Flue outlet positions and heights

Situation 1

At the ridge, if A is 600mm or less, then Bmust be not less than 600mm

Situation 3

Near openings, if A is 2300mm orless, then B must be not less than1000mm above top of opening.Situation 1 also applies as appropriate

Situation 2

At other positions on the roof, A must be not less than2300mm from the nearest point on the roof surface. B must be not less than 1000mm above the intersectionof the chimney stack and the roof surface, or at least ashigh as the ridge.

Situation 4

Near other buildings,if A is 2300mm orless, then B must benot less than 600mm. Situation 1 alsoapplies as appropriate

Adjoining building,within or outside

of boundary

Flue outlet positions and heightsFigure 13 shows the correct flueoutlet positions in 4 different roofsituations that ensure the products ofcombustion, in most wind conditions,are properly discharged and do notpresent a fire hazard. However,chimney heights and separationdistances may need to be increased ifsurrounding high buildings, high treesor ground could adversely affect fluedraught.

Read with ‘Roof pitch, openings andchimney performance’ in ‘Generalrequirements of heating systems’,page 12.

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Figure 14

Flue outlet positions from flammable roof coverings

Not less than 2300mm

1800mm

Flue outlets should be above the shaded area

Not less than

1800mm

Flammable clearancesWhere flues discharge close to readilycombustible roof coverings such asthatch or shingles, the distance betweenthese materials and flues should beincreased as shown in Figure 14. Read with Figure 13, page 22 for flueoutlet positions.

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Fireplaces, Chimneys, Flues and TerminalsDesign Considerations:Specific requirements of heating systems burning gas

Figure 1

Radiant convector fireTo BS 5871: Part 1

Decorative Fuel Effect (DFE) fireTo BS 5871: Part 3

Figure 2

Freestanding hearth

Ventilation for flued gas-fired appliances

Hearth projecting beyond fireplace recess

Hearth entirely within fireplace recess

Can be less than 300mmif hearth extends to a wall

Inset Live Fuel Effect (ILFE) fireTo BS 5871: Part 2

Flue size: 200mm minacross flue axis as forsolid fuel fire

Location: Fireplacerecess or undercanopy

Flue size: 175mm minacross flue axis

Location: Fully orpartially inset intofireplace recess

Flue size: 125mm minacross flue axis

Location: In front ofclosure plate fitted tofireplace opening

Open-flued appliancein a room/space

Open-flued appliance in a compartment ventilated via an adjoining room/space

A = 500mm2 per kW input in excess of 7 kW

A = 500mm2 per kW input in excess of 7 kWB = 1000mm2 per kW inputC = 2000mm2 per kW input

Open-flued appliance in a compartment ventilated direct to outside

D = 500mm2 per kW inputE = 1000mm2 per kW input

Permanent air supply requirements

1. Radiant convector fires andboilers, inset live fuel effect (ILFE) fires

The table below shows the type andamount of ventilation required forvarious types of flued gas burningappliance, but not including decorativefuel effect (DFE) fires.

These requirements should be read inconjunction with general air supplylocations, page 9 of ‘Generalrequirements of heating systems’.

2. Decorative fuel effect (DFE) fires

For a DFE fire in a fireplace recess with athroat, the permanent vent area shouldbe at least 10,000mm2.

For a DFE fire in a fireplace with nothroat, such as under a canopy, thepermanent air vent should be sized asfor a solid fuel open fire. (See ‘Specificrequirements of heating systemsburning solid fuel’, page 14)

Gas fire typesFigure 1 below shows some typicalarrangements for flued gas appliances.

Hearthsa) For the hearth requirements of

radiant convector gas fires andgas boilers, refer to ‘Specificrequirements of heating systemsburning solid fuel’, Figures 1 to 4,pages 15 to 16.

b) For the hearth requirements ofdecorative fuel effect (DFE) and insetlive fuel effect (ILFE) fires, refer toFigure 2 below.

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Fireplaces, Chimneys, Flues and TerminalsDesign Considerations: Specific requirements of heating systems burning gas

Figure 3

600mm min 600mm min

600mmmin

2000mm min

Flue/stack must not be within shaded area

Gas ridge terminal

1500mm min

For height relative toroof surface refer to BS 5440-1:2000

Stell gas terminal

Flue sizes for gas appliances

Flue sizesThe table below gives the minimum fluesizes for the safe, efficient performanceof all types of gas appliance.

Wall thickness around fluesA flue in a chimney should be enclosedby, or separated from another flue by,solid non-combustible material not lessthan 100mm thick. In addition, minimumseparation distances should bemaintained between a flue way and anycombustible material. Refer to ‘Specificrequirements of heating systemsburning solid fuel’, Figure 8, page 21.

Chimney pot or terminal supportFor the basic support of terminals forgas heating appliances, refer to ‘Specificrequirements of heating systemsburning solid fuel’, Figures 10 to 12,page 21.

However, for gas fires, special conditionsapply that limit actual flue terminaldesigns to one basic louvre type – Stellgas terminal inserts developed byHepworth and certified by British Gas.

Flue outlet positions andheightsFigure 3 below shows the correct flueoutlet positions that ensure the productsof combustion, in any wind conditions,are properly discharged and do notpresent a fire hazard.

Distance of flue outlets fromroof windowsTo ensure that fumes do not enter abuilding through roof windows, Figure 3below indicates the preferred location offlue outlets.

Type of installation Minimum flue sizeRadiant/convector fire New flue:

Circular, 125mm dia

Rectangular, 16,500mm2

cross sectional area with min dimension of 90mm

Radiant/convector fire Existing flue:

Circular, 125mm dia

Rectangular, 12,000mm2

cross sectional area with min dimension of 63mm

ILFE fire/DFE fire within Circular/rectangular flue,a fireplace opening up min dimension of 175mm(1)

to 500mm x 550mmDFE fire within a Circular/rectangular flue,fireplace opening more cross sectional area 15%than 500mm x 550mm of fireplace opening area

If proposals require morethan 15%, or more than120,000mm2, seek specialist advice

Note 1:Some ILFE and DFE appliances require a circular flue of atleast 125mm diameter

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Fireplaces, Chimneys, Flues and TerminalsDesign Considerations: Specific requirements of heating systems burning oil

Ventilation for flued oil-fired appliances

Figure 1

Hearth requirements – plan

Heatingapplance

Constructionalhearth outline

Perimeter of superimposedhearth must be clearly

marked

Front face

Not less than 150mm(225mm for an appliancewith visible flames orradiating elements)

Not less than 150mmto hearth perimeter orto heat resistant wall

Not less than 150mmto hearth perimeter or

to heat resistant wall

Open-flued appliancein a room/space

Open-flued appliance in a compartment ventilated via an adjoining room/space

A = 550mm2 per kW input in excess of 5 kW(1)

B = 1100mm2 per kW inputC = 1650mm2 per kW input

Open-flued appliance in a compartment ventilated direct to outside

D = 550mm2 per kW inputE = 1100mm2 per kW input

Note 1:If the appliance is fitted with a draught break, vent A shouldbe increased by a further 550mm2 per kW output

Permanent air supply requirementsThe table below shows the type andamount of ventilation required forvarious types of flued oil burningappliance. These requirements shouldbe read in conjunction with general airsupply locations, page 9 of ‘Generalrequirements of heating systems’.

HearthsFor the hearth requirements of oilburning appliances, refer to Figure 1.

Flue sizesA flue should be the correct size for aparticular heating appliance. Thismeans a flue must ensure an adequatedischarge velocity is achieved thatprevents flow reversal problems butdoes not result in excessive flowresistances.

The following options will meet theseobjectives:

a) Make the flue the same cross-sectional area as the appliance flueoutlet.

b) Make the flue larger so that at a laterdate, a flexible liner can be insertedthat matches the appliance oulet.

c) Make the flue larger where aplliancemanufacturer’s dictate this.

Chimney pot or terminal supportFor the basic support of terminals forgas heating appliances, refer to‘Specific requirements of heatingsystems burning solid fuel’, Figures 10to 12, page 21.

Heating Solutions

Fireplaces, Chimneys, Flues and TerminalsDesign Considerations: Specific requirements of heating systems burning oil

Figure 2

Gas ridge terminal(Not used with

vaporising burner

appliance)

Flue outlet used for:

(A) Appliance with pressure jet burner

(B) Appliance with vaporising burner

(A) 750mm min

(B) 2300mm min

(A) 600mm min

(B) 1000mm min

1500mm min

(Only relevant forpressure jet burnerappliance)

(A) 600mm min

(B) 1000mm min

Flue outlet positions andheightsFigure 2 below shows the correct flueoutlet positions that ensure the productsof combustion, in any wind conditions,are properly discharged and do notpresent a fire hazard. However, chimneyheights and separation distances mayneed to be increased if surrounding highbuildings, high trees or ground couldadversely affect flue draught.

Refer to ‘Specific requirements ofheating systems burning solid fuel’ forthe following requirements:

■ Hearths

■ Fireplace recess

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Fireplaces, Chimneys, Flues and TerminalsInstallation Details

Figure 1a

(The required numberof Flue Liners will be

determined by thenecessary minimum

chimney height of 4m– see page 11)

Flue Liners

Flue Adaptor

Chimney Pot

Components grouped together

Fitting the correct fireplace componentsA fireplace opening may be gathered invarious ways to receive a flue lining(including forming a throat if required).The size of the fireplace opening alsodetermines which Hepworth fireplacecomponents to use and the method ofinstallation. Different sizes of fireplaceopening are illustrated on pages 28 to 33.

How to build a fireplace opening up to 600mm wideAn opening up to 600mm wideincorporating a Milner Scored Firebackand Fireclay mortar also requires aFireplace Lintel 600 combined with anappropriate Flue Adaptor for round orsquare lined flues. Refer to Figures 1aand 1b.

This complete construction will form afireplace with a throat.

Adopt the following installation procedure:

■ Hepworth’s 2-piece Milner ScoredFireback is supplied in one sectionand should be separated along thehorizontal score line beforeinstallation.

■ The upper section should notoverhang the lower section andshould be set back from the lowersection by between 1.5mm and2mm. This is to prevent flamesfrom playing on the edge of the topsection, which can lead to earlydevelopment of cracks.

■ Fill the gap between the bottomand top section with a suitablesized non-combustible rope andpoint up with Fireclay mortar(Y137) to mix instructions.

■ The fireback may be subjected totemperatures in excess of 1000ºCduring operation, and the installationshould allow for expansion andcontraction particularly at the rearand sides of the fireback.

■ Thin strawboard, corrugatedcardboard or other expansionmaterials should be positionedimmediately behind the fireback.These materials are intended tochar in use and leave a space forexpansion purposes.

■ The space behind the firebackshould be filled and flaunched toensure a smooth passage forcombustion products into the flue.

■ The in-fill behind the fireback couldbe either vermiculite 6:1 Portlandcement or expanded perlite 8:1Portland cement. During filling,these compositions are wetted withjust sufficient water to enable themixture to bind together whenlightly compressed.

■ A fireback taken from open storageshould not be used for at least 48hours after installation to enable it toachieve room temperature. Thefireback should also be allowed todry out gradually by lighting a smallfire at the front of the grate. The fuelshould not directly touch thefireback. Over a further period of 48hours, the fire should be increaseduntil it is of normal size. Failure tofollow this could result in the firebackcracking almost immediately

■ Build in the back section (Y182) ofFireplace Lintel 600 and bed ontop of the fireback with Fireclaymortar (Y137).

■ Form a sloping infill, of fine concreteor brick, to continue the top line ofthe fireback into the back section(Y182) of Fireplace Lintel 600.

■ Build in the front section (Y181) ofFireplace Lintel 600, and bed upagainst Y182 with Fireclay mortar(Y137).

■ Build in the appropriate FlueAdaptor for either round or squareflue liners and bed on FireplaceLintel 600 with Fireclay mortar.

■ See page 34 for building a linedchimney flue. Hepworth recommendFlue Liner Jointing Compound (Y108).(Fireclay mortar must not be used forjointing flue liners)

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Figure 1b

Fireplace opening components installed

Chimney stack

Saddle flashing

Terracotta ridge tile (Two Hole Crested)

Ridge board

Sarking felt

Chimney breast

Roof tiles

Chimney stack

Flue Adaptor

Airbrick

Cavity Liner

Rafter

NoteFor forming or reconstructing 600mm wide fireplace

openings with throats in refurbishment projects, either ofthe following component methods may be used:

1. Otty Hood (plus structural lintel by others)

2. Throat Restrictor (plus structural lintel by others)

Contact Technical Advisory Service for further information

See note above for formingfireplace openings in

refurbishment projects

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Figure 2a

(The required number of Flue

Liners will be determined by the

necessary minimum chimney

height of 4m – see page 11)

Flue Liners

Chimney Pot

Corbel Unit Y110

Flue Adaptor

How to build a fireplace opening between 600mm and800mm wideAn opening between 600mm and800mm wide incorporating a firebackconstructed of Firebricks and Fireclaymortar also requires a Corbel Unit(Y110) and Fireplace Lintel (Y109)combined with an appropriate FlueAdaptor for round or square lined flues.Refer to Figures 2a and 2b.

This complete construction will form afireplace with or without a throat asrequired.

Adopt the following installation procedure:

■ EITHERTo accommodate a freestandingfire basket, line the fireplace recesswith Firebricks bedded and pointedin Fireclay mortar (Y137) to mixinstructions.ORTo accommodate an inset openfire, line the fireplace recess withFirebricks to form the sides (splayedif required) and back, ensuring thecorrect throat width is achieved atthe junction with Corbel Unit (Y110).Bed and point Firebricks withFireclay mortar (Y137) to mixinstructions.

■ Build in Corbel Unit (Y110).

■ Build in Fireplace Lintel 1000 andbed on top of the Corbel Unit withFireclay mortar.

■ Build in the appropriate Flue Adaptorfor round or square flue liners andbed on top of the Fireplace Lintelwith Fireclay mortar.

■ See page 34 for building a linedchimney flue. Hepworth recommendFlue Liner Jointing Compound (Y108).(Fireclay mortar must not be usedfor jointing flue liners)

Firebrick recess

(splayed sidesif required)

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Figure 2b

Chimney stack

Saddle flashing

Ridge board

Sarking felt

Chimney breast

Rafter

Roof tiles

Chimney stack

Flue Adaptor

Airbrick

Cavity Liner

Corbel Unit Y110

Fireplace Lintel 1000Decorative fireplacesurround

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Figure 3a

Flue Liners

Chimney Pot

Corbel Unit Y110

Flue Adaptor

Corbel Unit Y111

(The required number of Flue

Liners will be determined by the

necessary minimum chimney

height of 4m – see page 11)

How to build a fireplace opening between 800mm and1000mm wideAn opening between 800mm and1000mm wide incorporating a firebackconstructed of Firebricks and Fireclaymortar also requires:

Two Corbel Units (Y111 and Y110) andFireplace Lintel (Y109) combined with anappropriate Flue Adaptor for round orsquare lined flues. Refer to Figures 3aand 3b.

This complete construction will form afireplace with or without a throat asrequired.

■ The installation procedure is thesame as for a fireplace opening600mm to 800mm except forbuilding in an additional Corbel Unit(Y111) between the Firebrick linedfireplace recess and Corbel Unit(Y110).

■ See page 34 for building a linedchimney flue. Hepworth recommendFlue Liner Jointing Compound (Y108).(Fireclay mortar must not be usedfor jointing flue liners)

Firebrick recess

(splayed sidesif required)

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Figure 3b

Chimney stack

Saddle flashing

Ridge board

Sarking felt

Chimney breast

Rafter

Roof tiles

Chimney stack

Flue Adaptor

Airbrick

Cavity Liner

Corbel Unit Y110

Corbel Unit Y111

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Figure 5

Removing obstructions in the flue

Coring ball

Flue Linerscorrectly

Flue Linersincorrectly

Figure 4

Jointing flue liners

Rain or condensate may penetratean incorrectly, or badly, made jointinto the chimney constructioncausing failure

Excess jointing compound

Flue Liner

Void between liners and chimneyconstruction to be filled withightweight insulating infill

Flue liners to be laid with socketfacing upwards

How to build a lined chimneyflueThe Flue Liners (square or round)should be laid with the socket of eachsection uppermost and jointed withFlue Liner Jointing Compound (Y108)to prevent rainwater or condensatefrom penetrating the chimneystructure. See Figure 4.

Bed the first Flue Liner on the FlueAdaptor with Flue Liner JointingCompound, and continue beddingeach Flue Liner one above the otheruntil the desired height is achieved.Where offsets are unavoidable, see‘General requirements for heatingsystems’, page 10, and the offsetcalculation tables for configurationoptions available.

Any voids between the flue liners andchimney construction should be filledwith a weak lime mortar or lightweightinsulating concrete. Recommendedmixes are 10:1 perlite/cement or 6:1vermiculate/cement.

During construction, the chimneyshould be cored to remove all mortardroppings and obstructions that mightadhere to the inner surface of theliners. Coring, using a coring ball,should not be delayed untilconstruction is complete as mortardroppings may have hardened and bedifficult to remove. Alternatively, asimple method used by contractors isto pull an appropriately sized sack ofstraw up through the flue from itsbase as work proceeds. See Figure 5and also ‘Flue testing’ on page 35.

Following the completion of thechimney, a minimum period of 2weeks should elapse before it is usedto serve any fire or heating appliance.This is to allow an adequate drying outtime for the mortar to fully develop itsdesigned strength.

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Commissioning the heatingsystemTo prevent cracking, it is important thatthe first firing of the fireplacecomponents is taken up to a workingtemperature slowly. Initially a small fireshould be lit that is of relatively shortduration and only slowly built up tohigher temperatures.

Refer to page 28 for fireback dryingout procedure, and page 34 for mortardrying out procedure.

How to fit a chimney pot orterminalBed the base of the chimney pot orterminal into the masonry chimney stack:

■ Not less than 125mm, or

■ One quarter of the length of thepot or terminal.

Use whichever is the largest dimension,and refer to Figure 6 below for typicalbedding techniques for tapered andstraight-sided pots.

Form a weathered sand and cement(3:1) flaunching around the chimneypot or terminal above the corbelledbrickwork. Alternatively, bed a denseprecast concrete capping on thestack, and point around the chimneypot or terminal.

Flue testingNew chimney constructions should bechecked and tested for blockage andsoundness prior to use. These qualitiescan be assessed from a coring ball test(if a visual test cannot be carried out)followed by a smoke test. For thesetests the heating appliance if fitted, oropen fire, should not be alight.

The coring ball test involves gentlylowering a suitably sized metal orconcrete ball by rope from the chimneyterminal to the fireplace recess. It isonly necessary to carry out this testonce unless an obstruction is found. Inthis event, remove the blockage andrepeat the test to confirm free passagefor the ball. If mortar removal has beencarried out satisfactorily as the workproceeds, the coring ball test may notbe required. See Figure 5, page 34, forcoring procedure.

The smoke test is used to indicate thatthe flue adequately dischargescombustion products and does not leakbetween fireplace opening and terminal.

The smoke test procedure is as follows:

■ Warm the flue for about ten minutesusing a blowlamp or similar device.

■ Place 2 smoke pellets in thefireplace recess and ignite them.

■ Seal off the fireplace recess to allowthe smoke to rise through the flue.

■ The terminal should be sealedusing an inflatable rubber ball orpolythene bag.

■ Check for smoke leakage byexamining the chimney breast andadjoining walls at all levels inside thebuilding and at terminal level.Leakage can occur at somedistance from a fault because ofinfiltration into wall cavities, thereforeparticular attention should be paid atbargeboard overhangs and eaves.

■ Remember to remove the terminalseal after smoke testing has beensatisfactorily completed.Figure 6

Straight-sidedpot

Tapered pot

Flue liner

Cementmortar

flaunching

Cementmortar

flaunching

Chimney pot support

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Flue labelling A requirement of the BuildingRegulations is for a permanently fixednotice plate that gives the performancecapabilities of a hearth, fireplace, flueand/or chimney. Refer to page 10 forfurther information.

Installation Details

1. Building addressWhere work has been carried out

2. Identification of hearth, fireplace, chimney or flueE.g. open fireplace lounge, gas only, oil only

3. Firing capability: solid fuel/gas/oil/all fuelsE.g. All fuels, gas only, oil only

4. Intended type of applianceState type or make. If open fire give finished fireplace opening dimensionsE.g. open fire 480w x 580h (mm), radiant convector fire 6 kW input,

oil fired boiler 18 kW output (pressure jet)

5. Ventilation provisions for the applianceState type and area of permanently open air-ventsE.g. Hepworth clay cavity wall airbricks 10,000mm2

6. Chimney or flue constructiona) State the type or make and whether new or existing

E.g. New. Brick with Hepworth clay flue liners

b) Internal flue size e.g. 225mm dia

c) If clay or concrete flue liners are used confirm that they are correctlyjointed with socket end uppermost, and state jointing materials usedE.g. sockets uppermost Hepworth fireproof sealant Y109

d) If an existing chimney has been refurbished with a new liner, state type or make of liner fitted, e.g. Hepworth BS EN 1457 approved clay liners

e) Details of flue outlet terminalOutlet detail: e.g. Hepworth roll top 250mm internal dia, 750mm height.Complies with BS 13502 : 2002

f) Number and angle of bends e.g. 2 x 45º bends

g) Provision for cleaning and recommended frequency e.g sweep annually

7. Form of construction. New or existing?E.g. New. Tiles on concrete floor, 125mm thick

8. Inspection and testing after completionTesting carried out by: e.g. J Smith Building C..Tests (Appendix E in Approved Document J Building Regulations 2002)Flue inspection:

Visual: e.g. not possible due to bendsSweeping: e.g. OKCoring ball: e.g. OKSmoke test e.g. OK

Checklist certificate for hearths, fireplaces, flues and chimneys

been correctly installed and conform tothe requirements of ApprovedDocument J of the Building Regulations.Copies of the certificate are then issuedto all interested parties (client, buildingcontrol, subcontractor and maincontractor as appropriate).

Certification of installationA ‘checklist certificate’ must also becompleted that provides a summary ofall the constructional requirements ofhearths, fireplaces, flues andchimneys, providing certification thatall heating system components have

I/We the undersigned confirm that the above details are correct. In my opinion, these works comply with the relevant requirements ofApproved Document J of Schedule 1 to the Building Regulations.

Print name and title Profession

Capacity (e.g. proprietor of J. Smith Building Co Ltd. Tel. no.

Address Post code

Signed Date

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heating solutions

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clay flue

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fuel storage

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Documents

absorption heating & cooling solutions - … · absorption...

tank heating solutions

split system heating and cooling solutions€¦ · split...

heating with gas - tasso lake heating solutions inc

solar hot water heating solutions

welding, cladding and heating solutions

watlow heating solutions

hydronic heating and cooling solutions

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trigon xl - elco heating solutions

installation manual: radiant underfloor heating heating...

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2011 residential water heating solutions

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customer-focused and efficient. heating & cooling...

nexthermal industrial heating solutions