manual of modern hydronic heating

Manual ofModernHydronics

• Resident ia l

• Industr ia l

• Commercia l

• Snow and Ice Melt

Profess ional Radiant Heat ing Solut ions

S E C O N D E D I T I O N

MA N UA L O F MO D E R N HY D R O N I C S

This manual is published in good faith and is believed to be

reliable. Data presented is the result of laboratory tests and

field experience.

IPEX maintains a policy of ongoing product improvement. This

may result in a modification of features or specifications

without notice.

www.warmrite.com

www.ipexinc.com

© 2004 by IPEX. All rights reserved. No part of this book may

be used or reproduced in any manner whatsoever without prior

written permission. For information, address IPEX, Marketing,

2441 Royal Windsor Drive, Mississauga, Ontario L5J 4C7.

© 2004 IPEX WR003UC

INTRODUCTION

MODERN HYDRONICS

Each year, construction begins on tens of thousands of new buildings all across North America. Thousands moreundergo renovation. Whether new or remodeled, most of these buildings will require the installation or alterationof a comfort heating system. Along with hundreds of other decisions, the owners of these buildings musteventually select a heating system.

Unfortunately—and in most cases unintentionally—the choice is often based on factors that in the end, don’tprovide the comfort the owner or the occupants are expecting.

In many cases the heating system, which is often thought of as a necessary but uninspiring part of the building,is selected solely on the basis of installation cost. In other cases, the selection is based strictly on what thebuilder offers or recommends. Still other times, the choice is based on what’s customary for the type of buildingbeing constructed or its location. Such decisions often lead to years of discomfort in thermally-challengedbuildings. In retrospect, many people who have made such decisions—and lived with the consequences—wouldquickly change their mind if given the opportunity. Most would gladly spend more (if necessary) for a heatingsystem that meets their expectations.

It doesn’t have to be this way!

Few people don’t appreciate a warm, comfortable interior environment on a cold winter day. A warm home orworkplace lets them forget about the snow, ice, and wind outside. It’s an environment that encourages a senseof well being, contentment, and productivity.

Hydronic heating can provide such an environment. It can enable almost any building to deliver unsurpassedthermal comfort year after year.

Hydronics technology is unmatched in its ability to transfer precise amounts of heat where and when it’s needed.The warmth is delivered smoothly, quietly, and without objectionable drafts that cause discomfort, or carry dust

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THE IPEX MANUAL OF MODERN HYDRONICS

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and airborne pollutants through the building. Properlydesigned hydronic systems are often significantly lessexpensive to operate than other forms of heating.

A wide variety of hydronic heating options exist foreverything from a single room addition to huge industrial and commercial buildings. Knowledgeabledesigners can configure systems to the exact needs ofeach building and its occupants. The systems can thenbe installed without compromising the structure oraesthetics of the building.

In short, hydronic heating is for discriminating peoplewho expect buildings to be as comfortable to live andwork in as they are elegant to look at. Hydronic heatingsets the standard of comfort, versatility and efficiencyagainst which other forms of heating should bemeasured.

Now Is the Time

There has never been a better time for heating professionals to be involved with hydronics. Newmaterials, design tools and installation techniquesoffer unprecedented and profitable opportunities toprogressively-minded professionals.

IPEX produced this manual to assist you in deployinghydronic heating technology using the latest designand installation strategies. It is our goal to help you tomeet the exact needs of your customer using the finestmethods and materials available for modern hydronicheating. We want to inspire your thinking, and give youa “can do” attitude when faced with job requirementsthat often lead to compromise when undertakenwithout the versatility hydronics has to offer.

A Universal Piping System

Piping is obviously a crucial component in anyhydronic system. Not only must it safely contain heatedand pressurized water but it must also resist corrosion,withstand thermal cycling and be easy to install.

Kitec® XPATM pipe was launched by IPEX in 1988 as amultipurpose pressure pipe with many potential uses inhydronic heating, including potable water distribution.Kitec’s construction combines the best properties ofboth aluminum and cross-linked polyethylene (a.k.a.PEX) to create a unique composite tube that can beused in applications often beyond the limits of eithermetal or plastic alone.

The aluminum core of Kitec pipe provides strength,yet allows for easy bending. It results in a tube thatexpands and contracts far less than all plastic tubingwhen heated and cooled. It also provides an extremelyeffective barrier against oxygen penetration, which canlead to corrosion of other hydronic system components.

The outer PEX layer protects the integrity of thealuminum core, shielding it from abrasion or chemicalreactions when embedded in materials such asconcrete. The inner PEX layer provides a smoothsurface for excellent flow characteristics as well aschemical resistance.

The unique construction of Kitec tubing also providesexcellent flexibility for easy installation, especially intight situations where rigid pipe is simply out of thequestion.

Unlike most plastic tubing, Kitec retains the desiredshape when bent. It can also be easily straightened fora neat and professional appearance in exposedlocations.

Kitec pipe is truly a “universal” product suitable for alltypes of service in hydronic heating systems. Fromheated floor slabs, to heated walls and ceilings orsnowmelting systems to baseboard circuits, you’ll findthe qualities Kitec possesses will soon make it thetubing of choice for all your hydronic heating needs.

From piping to systems

In addition to Kitec tubing, IPEX also offers acomplete line of accessories such as tubingconnectors, adapter fittings, manifolds and WarmRiteFloor® Control Panels. These products are designed toallow fast and easy installation and can be used in avariety of applications.

In the sections that follow, we’ll show you how to applythese products in new ways that let you design andinstall systems that epitomize the quality and comforthydronics has long been known for. These aretechniques that let you profitably take on thechallenging jobs others stay away from while steadilybuilding your reputation as a true comfort professional.

Together with IPEX, you can successfully harness thealmost endless possibilities offered through modernhydronics technology.


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Section 1: Consider the Possibilities! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Section 2: Heat Source Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Section 3: Water Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Section 4: Radiant Floor Heating Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Section 5: Radiant Walls and Ceilings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Section 6: Manifold Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

Section 7: Pre-Assembled Control Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

Section 8: Distribution systems for Hydronic Heating . . . . . . . . . . . . . . . . . . . . . . . .87

Section 9: Designing Multiple-Load Hydronic Systems . . . . . . . . . . . . . . . . . . . . . . .99

Section 10: Radiant Pipe and Tubing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109

Section 11: Hydronic Snow and Ice Melting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115

Section 12: IPEX RadiantTM Design Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131

Appendix

TABLE OF CONTENTS

SECTION

1

CONSIDER THE POSSIBILITIES!

Question:

What kinds of heating loads can be handled using modern hydronics technology?

Answer:

Almost any load you can think of!

For years the concept of hydronic heating evoked thoughts of cast-iron radiators or fin-tube baseboards in homesand commercial buildings—and not much else.

Early hydronic systems were usually classified as being “residential” or “commercial” in nature. Residentialsystems were the domain of plumbing / heating contractors. Rule of thumb design was usually good enough giventhe limited variety of systems installed. The piping and control methods used in these systems remained essen-tially unchanged between the 1950’s and the 1980’s in North America.

Commercial hydronic systems were a world apart from their residential counterparts. Techniques such as primary/ secondary piping, multiple water temperature distribution systems, and outdoor reset control were successfullydeployed in commercial systems, but almost never considered for residential applications.

A New Era for Hydronics

Times have changed considerably, hydronically speaking. Residential and commercial systems now share somecommon piping and control strategies. Successful installation strategies first developed decades ago are being“redeployed” using modern materials and control strategies that ensure decades of reliable and energy efficientoperation.

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The days when hydronic systems consisted solely ofcast-iron radiators, copper or black iron pipe and fin-tube baseboard are gone. New hardware such as Kitecpipe and WarmRite Control Panels now make itpossible to install quality systems that serve amultitude of heating loads. Modern systems can incor-porate a variety of heat emitters. Each are selected tomatch the exact thermal, aesthetic and budgetconstraints of a project.

Today, hydronic heating contractors are being asked tofurnish heating systems for everything from smallapartments to large custom-built houses, as well as avariety of commercial buildings. Each job brings itsown particular set of requirements.

Many modern systems contain several types of heatemitters operating at different water temperatures anddivided up into a dozen or more independentlycontrolled zones.

Some contractors hesitate to take on such challengingsystems. Others recognize that with the right materialsand design methods, these systems are not onlypossible, but also offer excellent profit potential as wellas the likelihood of future referrals.

Contractors who recognize what modern hydronicstechnology has to offer, and who take the time to learnhow to apply new design techniques and hardware, areenjoying unprecedented business growth.Discriminating clients seek out these hydronicspecialists because they offer what their competitioncannot—the ability to pull together modern materialsand design methods to create heating systems specifi-cally tailored to their client’s needs.

To take advantage of such opportunities, you need toknow how to use these modern piping and controltechniques. That’s what this manual is all about. It willshow you how to use Kitec pipe, WarmRite ControlPanels, and other hardware to assemble state-of-the-art hydronic systems that deliver comfort, economicaland reliable operation and most importantly, satisfiedcustomers. Armed with this knowledge you’ll findmodern hydronic heating to be among the most satis-fying and profitable niches in the HVAC industry.

IPEX Incorporated is ready, willing, and able to helpyou achieve the many benefits offered to those whoknow how to apply modern hydronics technology.

One System that Does It All

The concept that best describes modern hydronicheating is:

One heat source serving multiple loads

Those loads include:

• Radiant heating of floors, walls and ceilings• Baseboard heating• Panel radiators• Hydro-air subsystems• Indirect domestic water heating • Intermittent garage heating• Pool and spa heating• Snow melting• “District heating” of several adjacent buildings• Agricultural / horticultural loads such as

animal enclosures, greenhouse heating, and turf warming

Many projects may have several of these loads, eachrequiring heat in different amounts, at different timesand at different temperatures.

For example, the space heating loads of a givenbuilding might best be served by a combination ofhydronic heat emitters. Some areas might be perfectfor radiant floor heating while others are better suitedto radiant ceiling heating. Still other areas might beideal for baseboard or even ducted forced-air throughan air handler equipped with a hot water coil.

Almost every house and commercial building alsoneeds domestic hot water. In some cases, this load canbe as large or larger than the space heating load.

Many facilities are also perfect candidates for hydronicsnow melting - if those in charge are aware of thebenefits it offers compared to traditional methods ofsnow removal.

Some designers approach situations like these byproposing a separate, isolated hydronic system for eachload. One boiler to heat the building, another to meltthe snow in the driveway, and perhaps still another toheat the pool. The same building might also use one ormore direct-fired domestic water heaters.

Although such an approach is possible, it seldom takesadvantage of the unique ability of hydronics to connectall the loads to a single heat source. The latterapproach often reduces the size and cost of the overallsystem. It also makes for easier servicing and reducesfuel consumption. Such a synergistic system is madepossible through modern hydronics technology.

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From Simple to Sophisticated

Let’s look at the versatility of modern hydronicstechnology in meeting the demands of both simple andsophisticated load requirements.

We’ll start with something basic: a floor heating systemfor a small addition to a home. Because the load issmall, a water heater will be used as the heat source.It, as well as the other system components, is shown infigure 1-1

Although the installer could purchase components(such as the manifolds, a bronze circulator, expansiontank) and all the valving separately, using a WarmRitecontrol panel can save much time and labor. All theneeded components are preassembled into a compact

and easily mounted unit. All that’s left to do is to pipe

the WarmRite control panel to the water heater,connect the floor circuits, and then route power to it.

Although this system is very simple in concept andconstruction it’s also capable of delivering comfort farsuperior to its alternatives, several of which may costmore to install as well as to operate.

A Slightly Larger Requirement

A typical home often has a design heating load greaterthan what can be supplied from a residential waterheater, especially if the same unit also has to supplydomestic hot water. In such cases a boiler is a moreappropriate heat source.

Figure 1-3 is an example of a hydronic system that

SECTION 1 CONSIDER THE POSSIBILITIES

Figure 1-1

Figure 1-2

Figure 1-3


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supplies space heating through a radiant floorsubsystem as well as domestic hot water via an indirectwater heater.

Two WarmRite control panels are used to provide thewater and electrical control functions for the spaceheating portion of the system. In this case, electricvalve actuators have been included in the WarmRitecontrol panels to allow individual temperature controlof several rooms. An external injection mixing systemhas been installed between the WarmRite controlpanels and the primary loop, to vary the water temper-ature supplied to the floor circuits based on outsidetemperature (e.g. outdoor reset control). This mixingsystem also protects the boiler from flue gas conden-sation that can be caused by low return water temper-atures.

Multiple Water Temperatures...No Problem

Some buildings may require (or some customers mayprefer) different types of hydronic heat emitters thatoperate at different water temperatures. For example, aportion of a building may use radiant floor heating. Thetubing circuits in the heated floor slab might operate at105 deg. F. water temperature at design conditions.

Another part of the building may be heated with fin-tube baseboard that needs 180 deg. F. water at thesame time. Providing these multiple water tempera-tures is relatively straightforward using thepiping/control scheme depicted in figure 1-4.

Notice that the manifold supplying the baseboardcircuits is piped directly into the primary loop and thusreceives hot (180 deg. F.) water. The floor heatingcircuits are supplied with reduced water temperaturethrough use of an injection mixing system and theWarmRite control panel. Note that all componentsrelated to run the floor heating circuits are integratedinto one preassembled WarmRite control panel. Theboiler also supplies hot (180 deg. F.) water to the heatexchanger of the indirect water heater for fast recovery.

This system now serves three different heating loadsusing two water temperatures. But that’s far frompushing the limits of modern hydronics technology.

A Sophisticated System

Suppose that after discussing the above system, yourcustomer asks if you can also provide snow melting,occasional garage heating or pool heating. Maybe evenall three at the same time. This is an opportunity where

Figure 1-4

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hydronics can really come through. It is a situationwhere you can provide an efficient customized systemthat’s exactly right for your customers needs.

Figure 1-5 depicts one way such a system could beassembled.

Think of this system as a collection of subassemblies“plugged” into a common source of heated water: theprimary loop. The floor heating subassembly appearsthe same as in figure 1-4 except now there are two ofthem. It’s simply plugged into larger primary loop.Likewise, the manifold supplying the baseboard zonesis plugged into the primary loop the same as in figure1-4.

What’s new are the subassemblies that supply the heatexchanger for the snow melting and pool heatingsystems. Think of the heat exchangers as theseparating point between the hot water in the primaryloop and the fluids that carry heat to the snow meltingcircuits and the pool. The heat gets passed from onefluid to the other, but the fluids themselves never mix.

The “power plant” for this sophisticated system is a

pair of boilers controlled by a staging control. Thisconcept—called a multiple boiler system—is nowcommon in larger residential as well as commercialsystems. The multiple boiler system is sized to deliverthe proper amount of heat when all the loads that arecapable of running simultaneously are doing so. Suchan approach yields higher seasonal efficiencycompared to a single large boiler. It also adds to thesystem’s reliability since one boiler can still operateshould the other be down for service.

The system shown in figure 1-5 uses state-of-the artpiping and control techniques to serve all the heatingloads of a large house with many amenities. It alsomakes use of Kitec and WarmRite hardware to speedinstallation and ensure top quality.

The sections to follow discuss many of the keyconcepts and available options for assembling bothsimple and sophisticated hydronic systems. Learnthem, apply them, and then take pride in providingyour customers with the comfort and efficiency thatonly modern hydronics technology can deliver.

SECTION 1 CONSIDER THE POSSIBILITIES

Figure 1-5

SECTION

2

HEAT SOURCE OPTIONS

A wide variety of heat sources can be used with hydronic heating systems. They include gas- and oil-fired boilers,hydronic heat pumps and domestic water heaters to name a few. Some are better suited to higher temperaturesystems, while others are ideal for low temperature systems.

This section briefly describes the characteristics of several heat sources suitable for hydronic systems. Moredetailed information pertaining to their selection and installation is best found in manufacturer’s literature andmanuals. Relevant building / mechanical codes should also be consulted for specific installation requirement.

The information at the end of this section allows designers to compare the cost of energy provided by severalcommon fuels based on their local cost and the efficiency at which they are converted to heat.

2-1 Conventional Boilers

The most common hydronic heat source is a “conventional” gas- or oil-fired boiler. They are available with heatexchangers made of cast-iron, steel and finned copper tubing.

Although designed to operate at relatively high water temperatures, conventional boilers can be adapted to lowertemperature hydronic systems such as radiant floor heating by using a mixing device. Their ability to producehigh temperature water makes them a good choice in systems where both low temperature and high temperatureheat emitters are used.

The term “conventional” describes boilers that are intended to operate without sustained condensation of the fluegases produced during the combustion process inside the boiler. These flue gases are made up of water vapor,carbon dioxide, and trace amounts of other combustion products depending on the fuels used, and the tuning ofthe burner.

All boilers experience temporary flue gas condensation during cold starts. If the boiler is connected to a low mass

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distribution system that is designed to operate athigher water temperatures—fin-tube baseboard forexample—such flue gas condensation is short-lived. Itrapidly evaporates as the boiler warms above the dewpoint of the exhaust gases.

However, when a conventional boiler serves as the heatsource for a low temperature distribution system it isimperative to keep the inlet temperature to the boilerabove the dew point of the exhaust gases. For gas-firedboilers, the inlet water temperature during sustainedoperation should not be less than 130 deg. F. For oil-fired boilers, it should not be less than 150 deg. F.

Failure to provide such boiler inlet temperatureprotection will cause the water vapor (and othercompounds present in the exhaust gases) to contin-ually condense on the internal heat exchangersurfaces. The acidic nature of such condensate cancause swift and severe corrosion along with scaleformation inside the boiler. It can also rapidly corrodegalvanized vent piping, as well as the deterioration ofmasonry chimneys

Hydronic distribution systems with high thermal masscan also cause prolonged flue gas condensation as thesystem warms up to normal operating temperature. Acool concrete slab with embedded tubing circuits is agood example. As the slab begins to warm, its thermalmass can extract heat from the circulating waterstream 3 to 4 times faster than normal. Since the rateof heat release from the water is much higher than therate of heat production, the water temperature (in anunprotected boiler) will quickly drop well below thedew point temperature of the exhaust gases. The boilercan operate for hours with sustained flue gas conden-sation. Such a situation must be avoided.

The key to avoiding low boiler inlet water temperatureis preventing the distribution system—whatever type ithappens to be—from extracting heat from the waterfaster than the boiler can produce heat.

Modern mixing devices can automatically monitor and

adjust boiler return temperature by limiting the rate ofheat transfer allowed to pass through a mixing deviceand into the distribution system. The piping concept isshown in figure 2-1. The details involved in providingboiler return temperature protection will be discussedin section 3.

2-2 Condensing Boilers

In contrast to conventional boilers, gas-firedcondensing boilers are specifically designed to promotecondensation of the water vapor that is producedduring combustion. They use large internal heatexchanger surfaces to coax as much heat as possiblefrom the exhaust gases. The heat exchanger surfacesare made of high-grade stainless steel or other specialalloys, and are not corroded by the acidic condensatethat forms as the flue gases cool below the dew point.When properly applied in low temperature hydronicsystems, such boilers can attain efficiency of 95+ %.

Although they are more complicated and moreexpensive than most conventional boilers, condensingboilers are well suited for low temperature hydronicsystems such as slab-type floor heating, snow melting,pool heating and low- to medium- temperaturedomestic water heating. The lower the temperature ofthe water returning from the distribution system, thegreater the rate of condensate formation, and thehigher the boiler’s efficiency.

Although condensing boilers can be used as heatsources for higher temperature hydronic systems, thisis generally not advisable. The higher operating watertemperatures prevent the boiler from operating withsustained flue gas condensation. Under such condi-tions their efficiency is comparable to that of a conven-tional boiler. Again, the key to attaining high efficiencyfrom a condensing boiler is matching it with a low-temperature distribution system.

Systems with condensing boilers typically do NOT usemixing devices between the boiler and the distribution

Figure 2-1 Figure 2-2

15

system. This helps offset a portion of the boiler’s highercost. Most condensing boilers can also be side wallvented through a 2” CPVC pipe. This too lowers instal-lation cost relative to boilers vented through a chimney.Figure 2-2 shows how a condensing boiler would bepiped in a typical floor heating system.

2-3 Tank-type Water Heaters

Some hydronic systems can use tank-type domesticwater heaters as their heat source. Usually the size ofsuch systems is limited by the heating capacity of thewater heater. Residential water heaters have heatoutputs in the range of 15,000 to 40,000 Btu/hr. Thisusually limits their application to small apartments ormodest residential additions.

Because tank-type water heaters are designed tooperate at lower water temperatures, mixing devicesare not usually used between the tank and the distri-

bution system. The tank is directly piped to the distri-bution system as shown in figure 2-3. The tank’sthermostat is set for the desired supply water temper-ature.

In some systems a water heater is expected to supplyboth domestic hot water and space heating. Althoughpossible under some circumstances, the designer mustensure that the heating capacity of the water heatercan handle both the space heating and domestic waterheating loads. If these loads occur simultaneously, it isusually necessary to make the domestic water heatingload a priority over the space heating load. Temperaturecontrols can be used to temporarily suspend heatoutput to the space heating system until the domesticwater heating load subsides and the tank temperaturerecovers.

Opinions vary on the suitability of circulating potablewater through the space heating circuits. Under somecircumstances, the potable water can remain stagnantin the space heating circuits for several monthsallowing for the possibility of microbe growth. Becausepotable water is used in the space heating circuits, allmetal components must be bronze or stainless steel toresist corrosion from the oxygen-rich water. There isalso the possibility of scale or sediment in the spaceheating system due to contaminants in the potablewater.

The preferred approach to such “dual use” systems isto separate the space heating portions of the systemfrom those containing domestic water using a smallstainless steel heat exchanger as shown in figure 2-4.Because the heat exchanger isolates the space heatingcomponents the distribution system must have anexpansion tank, pressure relief valve and air separator.

SECTION 2 HEAT SOURCE OPTIONS

Figure 2-3

Figure 2-4


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2-4 Geothermal Heat Pumps

Geothermal heat pumps are one of the newest heatsources suitable for some types of hydronic heatingsystems. They extract low temperature heat from atubing circuit buried in the earth, or directly from waterwells or other sources of water such as a large pond orlake. Using a refrigeration system similar to that in acentral air conditioner, the heat captured from theearth is boosted in temperature and then transferred toa stream of water flowing to the distribution system.

As with condensing boilers, no mixing device isrequired between the heat pump and the distributioncircuits. However, if the distribution system is dividedinto several independently controlled zones, aninsulated buffer tank should be installed between theheat pump and the distribution system as shown infigure 2-5. This tank allows the heat output rate of theheat pump to be different than the heat extraction rateof the distribution system. It prevents the heat pump

from short cycling under low load conditions.

As with condensing boilers, geothermal heat pumpsattain their highest efficiency when matched to low-temperature distribution systems. Slab type radiantfloor heating systems operating at water temperaturesin the range of 100 to 115 deg. F. at design conditionsare ideal. The lower the water temperature, the higherthe heat pump efficiency the system can operate at.

Avoid geothermal heat pumps in systems requiringdesign water temperatures above 130 deg. F.

In addition to heating, geothermal heat pumps can alsosupply chilled water for hydronic cooling applications.The most common approach uses an air handlerequipped with a chilled water coil. Other terminal unitssuch as radiant ceiling panels can be used for chilledwater cooling, but such systems require accurate andreliable dew point control to avoid condensation on thechilled surfaces. A separate air handler is usuallyrequired to control humidity.

Figure 2-5

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2-5 Thermal Energy Storage Systems

Many electric utilities offer “off-peak” electrical rates.Power that is purchased during off-peak hours isusually much less expensive than during periods ofhigh demand.

A hydronic heating system is an excellent means oftaking advantage of these rates. The idea is topurchase the electricity during the off-peak period andstore the energy as heated water. This water is thenused to heat the building during the “on-peaks”periods when electrical rates are higher. A schematicshowing how this concept can be implemented isshown in figure 2-6.

The beginning of an off-peak charging cycle is initiatedby a switch contact in the electric meter. At this point,one or more electrical heating elements are turned onto heat water in the large, well-insulated storage tank.Charging continues for several hours, and the tankbecome progressively hotter. If heat is needed by the

building during the charging cycle, some of the tankwater is routed out through the distribution system thesame as any other time of day. By the end of thecharging cycle the water temperature in the tank maybe as high as 200 deg. F. When the switch contact inthe meter opens, the electrical elements are turned off.The hot water in the tank contains the heat needed formost if not all of the “on-peak” hours to follow.

Low temperature distribution systems such as radiantfloor heating are ideally suited to such a heat source.Their low operating temperature allows the tank to bedeeply discharged and thus maximizes its heat storagecapability. The heat stored in a heated floor slab alsoallows the system to “coast” through the last 2 to 4hours of the on-peak period should the energy in thetank be depleted.

A mixing device installed between the storage tank andthe distribution system automatically reduces the watertemperature supplied to the distribution system asnecessary.


Figure 2-6


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2-6 Wood-fired Boilers

When firewood is readily available and competitive incost with conventional fuels, wood-fired boilers areanother possible hydronic heat source.

In some systems, a wood-fired boiler is used in tandemwith a conventional fuel boiler. The piping concept isshown in figure 2-7. Each boiler is piped as asecondary circuit into a common primary piping loop.This arrangement allows either boiler to operatewithout circulating hot water through the other(unfired) boiler, thus reducing heat loss. Systemcontrols are usually configured so the conventional fuelboiler automatically assumes the load as the fire diesdown in the wood-fired boiler.

Heat output from a wood-fired boiler is harder tocontrol than that from a conventional boiler. A largevolume of water in the system adds to its stability. The

water volume may be contained in the wood-fired boileritself or in a separate insulated thermal storage tank.Such a tank must be well insulated so that it can storeheat for several hours with minimal losses. The conceptis also shown in figure 2-7.

Some wood-fired boilers are not pressure rated. Thewater chambers inside the boiler are vented directly tothe atmosphere. Although opinions vary on how best toconnect such “open system” boilers to hydronic distri-bution systems the conservative approach is to installa stainless steel heat exchanger to isolate the boilerwater from that in the pressurized distribution system.Not only does this allow the distribution system to bepressurized for quiet, air-free operation, but it alsoprotects the cast iron and steel components in thedistribution system from the possibility of corrosionthrough contact with boiler water that has a higherconcentration of dissolved oxygen.

Figure 2-7

19


2-7 Comparing Fuel Costs

In many cases the heat source is selected based on thetype of fuel that is available or determined to be mosteconomical over the life of the system. The commonlyused fuels are sold in different units such as kilowatt-hours for electricity, therms for natural gas, gallons forfuel oil and face cords for firewood. To perform anaccurate comparison it is necessary to express the costand energy content of each candidate fuel on a

common basis.

The formulas in figure 2-8 allow the cost of heatingenergy from each of several fuels to be expressed onthe common basis of dollars per million Btu’s ofdelivered heat. This is abbreviated as $/MMBtu. Theseformulas take into account the cost, purchase units, aswell as efficiency of the heat source in converting thefuel into useful heat.

Figure 2-8

SECTION

3

WATER TEMPERATURE CONTROL

All hydronic heating systems must control the water temperature supplied to their heat emitters. A simple systemmay only need to supply one water temperature to all the loads it serves. A more sophisticated system containingseveral types of heat emitters may need to simultaneously supply two or more water temperatures.

This section discusses several methods of water temperature control and the hardware necessary to accomplish it.

3-1 Setpoint control

The simplest method of water temperature control is called“setpoint control.” As its name implies, a single (set) watertemperature is supplied to the distribution system regardless ofwhich loads are active, or how great the demand for heat is (as longas there is a demand).

To prevent short cycling of the heat source or other equipment inthe system, setpoint controls require an operating differential. Thisrefers to the variation in temperature between which control closesor opens its electrical contacts. A contact closure is the mostcommon way to turn the heat source on and off. For example, asetpoint control with a setting of 180 deg. F. and a differential of10 deg. F. would turn the heat source off at 180 deg. F. and backon when it the temperature drops to 170 deg. F.

Some setpoint controls “center” their differential on the setpoint.A device of this type, when set to 180 deg. F. and a 10 deg. F.differential, would open its electrical contacts to turn the heat

21Figure 3-1


22

source off at 185 deg. F. and close them when thesensed temperature drops to 175 deg. F. Figure 3-1compares these two types of setpoint control.

Some setpoint controls have fixed (non-adjustable)differentials, while others provide an adjustable differ-ential. The narrower the differential, the closer thewater temperature stays to the desired setpoint.However if the differential is too narrow, the heatsource or other equipment in the system couldexperience excessively short operating cycles thatreduce their efficiency and shorten their life. Heatsource operating differentials in the range of 10 deg. F.are common in hydronic systems.

Systems using setpoint controls provide the sameaverage water temperature to the loads whenever thereis a call for heat, regardless of the rate of heat inputrequired by the load. For example, a boiler operated bya setpoint control supplying a circuit of fin-tubebaseboard would deliver hot water (perhaps averagingaround 175 deg. F.) whether the outdoor temperaturewas -10 deg. F. on a cold January night, or 50 deg. F.on a mild October afternoon. To prevent overheatingunder all but design load conditions, flow must beperiodically interrupted by turning off the circulator orclosing the zone valves. To keep room temperaturevariations to a minimum, it’s important to have athermostat with a narrow differential of perhaps 1 or 2deg. F. If the thermostat has an anticipator it should becarefully set for the electrical current flow through itduring its on-cycle.

3-2 Outdoor reset control

Rather than deliver heat in “spurts,” an ideal systemwould continually adjust its rate of heat delivery tomatch the heat loss of the building. The indoor airtemperature would remain constant, and there wouldbe no difference in comfort regardless of outside condi-tions.

Outdoor reset control (ORC) was developed for thispurpose. It enables heat to flow from the heat emittersto the space being heated at just the right rate. ORC isincreasingly recognized as the preferred method ofwater temperature control, especially for high thermalmass floor heating systems.

All outdoor reset controls use outside air temperatureto determine the ideal “target” water temperature to besupplied to the system’s heat emitters. The colder it isoutside, the higher the water temperature. The goal isto match the rate of heat delivery to the rate of heatloss from the building.

There are two methods of using reset control in ahydronic system. Each can be used by itself, or the twocan be used in combination.

They are:

1. boiler reset control

2. mixing reset control

A boiler reset control takes over operation of the burnerfrom the standard (fixed) high limit control suppliedwith most boilers. As the outside air temperaturechanges, the reset control continually recalculates howhigh the boiler water temperature will be allowed toclimb and operates the burner accordingly.

Boiler reset is well suited for systems using relativelyhigh temperature hydronic heat emitters, likebaseboard or panel radiators. However, becauseconventional boilers should not operated for prolongedperiods at temperatures below the dew point of theirexhaust gases, boiler reset is limited when used inconjunction with low temperature heat emitters. Insuch cases, boiler water temperature can only“partially reset” down to a user-selected minimumtemperature setting as shown in figure 3-2.

For the case shown, the boiler outlet temperaturewould not be reduced below 140 deg. F. This watertemperature happens to correspond to an outside airtemperature of 25 deg. F. Air temperatures of 25 deg.F. and higher represent a large percentage of theheating season in many parts of North America. Thisimplies the 140 deg. F. water temperature supplied tothe heat emitters will be higher than necessary duringmuch of the heating season. The room thermostat mustturn the circulator (or zone valve) on and off to preventoverheating under these conditions.

Figure 3-2

23

Mixing reset control requires a mixing assemblybetween the boiler loop and a separate distributioncircuit. This assembly could contain a modulating 2-way, 3-way, or 4-way valve, or a variable speed injectionpump as depicted in figure 3-3. These options arediscussed in more detail later in this section.

The mixing assembly provides the proper supply watertemperature to the distribution system. Whennecessary, it also acts as a “clutch” to prevent the coldthermal mass of a distribution system from extractingheat faster than the boiler can produce it. This latterfunction, commonly called “boiler protection,” iscrucially important when a conventional boiler providesheat to a slab-type floor heating system.

Mixing reset control allows “deep” reduction in thewater temperature supplied to the distribution systemwhile simultaneously protecting the boiler from lowinlet water temperatures.

Boiler reset can be used in combination with mixingreset in the same system. The concept is shown infigure 3-4.

The boiler reset control monitors and adjusts the watertemperature in the primary loop by varying the firingcycles of the boiler(s). The primary loop temperature isoften partially reset to prevent the boiler(s) fromoperating below dew point temperature. The mixing

reset control operates the mixing device to reduce theprimary loop water temperature as appropriate for theloads they serve. Some systems may have two or moreindependent mixing devices supplied from a commonprimary loop.

SECTION 3 WATER TEMPERATURE CONTROL

Figure 3-3

Figure 3-4


24

An example of the reset lines for a system using bothboiler reset and mixing reset is given in figure 3-5.Notice that the primary loop has a minimum supplytemperature of 140 to protect the boiler fromsustained flue gas condensation. However, the mixingreset control can reduce the temperature of the waterto the distribution system all the way down to room airtemperature.

3-3 Mixing requirements

Several types of mixing devices can be used to reducethe water temperature supplied from the heat source tothe distribution system. These include 2-way, 3-way,and 4-way valves as well as several forms of injectionmixing.

Controlling the water temperature supplied to thedistribution system is often not the only function of themixing device. In systems using a conventional boileras the heat source the mixing device must also preventlow inlet water temperatures that can cause sustainedflue gas condensation within the boiler.

This second requirement applies when any type of fuel-burning boiler—that’s not designed to operate withsustained flue gas condensation—is paired with a lowtemperature distribution system. Most “conventional”

gas- and oil-fired boilers fall into this category. Failureto provide this protection can result in severe corrosionand scaling within the boiler. This not only shortensboiler life, but it can also lead to failure of vent pipingand spillage of combustion products into the building.Unfortunately, the need to protect the boiler inlettemperature is often viewed as secondary to providingthe proper supply temperature to the distributionsystem. This is an oversight with potentially deadlyconsequences.

It is generally recognized that maintaining returntemperatures of 130 deg. F. or higher for gas-firedboilers, and 150 deg. F. or higher for oil-fired boilerswill eliminate the damaging effects of flue-gas conden-sation. There are exceptions, and boiler manufacturersshould be consulted regarding the minimum operatingtemperature of their equipment.

Condensing boilers, discussed in section 5, are specif-ically designed to withstand sustained flue gas conden-sation and don’t need return temperature protection.The cooler the return water temperature the highertheir efficiency. In most cases a mixing device is notneeded when a condensing boiler is used to supplyheat to a low temperature hydronic distribution systemas long as the supply temperature matches the designcriteria.

Figure 3-5

25

Hydronic heat sources that don’t produce flue gasesdon’t need to be protected against flue gas conden-sation. These include electric boilers, hydronic heatpumps, thermal storage tanks, and heat exchangers.

3-4 3-way thermostatic mixing valves

One of the most common mixing devices used in lowtemperature hydronic systems is a 3-way thermostaticvalve. It has two inlet ports—one for hot water, theother for cold—and a single outlet port for the mixedstream. Inside the valve is a shuttle mechanism thatdetermines the proportions of hot and cold waterallowed into the valve. The shuttle is moved up anddown inside the valve body by the expansion andcontraction of a wax-filled actuator. The sealed waxassembly is heated by the mixed flow across it. If themixing stream is slightly too hot, the wax assemblyexpands, forcing the shuttle to partially close the hotinlet port and simultaneously open the cold inlet port.

A knob on the valve sets the actuator to the desiredoutlet water temperature. As the temperatures of theincoming hot and cold streams change, the wax-filledactuator moves the shuttle to maintain the set outletwater temperature.

Some 3-way mixing valves are operated by a gas-filled

bellows actuator rather than an internal wax-filledactuator. Their sensing bulb contains a fluid thatincreases in pressure when heated. This increasedpressure causes the valve to partially close the hotwater port as it opens the cold water port. A knob onthe valve is used to set the desired mixed watertemperature.

The preferred location of the temperature-sensing bulbis downstream of the distribution loop circulator. Thisensures thorough mixing by the time the flow passes bythe sensing bulb. Improper placement of the sensingbulb can cause erratic operation. The most accuratetemperature sensing takes place with the sensing bulbis immersed in the flowing water. If this is not possiblethe bulb should be tightly strapped to the pipe andcovered with pipe insulation.

The piping schematics in figure 3-6 show one pipingarrangement for a 3-way valve. This pipingarrangement is appropriate if (and only if) low inletwater temperatures or reduced flow rates under lowload conditions do not adversely effect the heat source.

Reduced boiler flow rate is seldom a problem for highmass boilers or storage tanks. However, low massboilers, heat pumps or electric boilers may require aminimum flow rate whenever they operate. In such


Figure 3-6


26

cases, the heat source should be equipped with its ownpumped bypass circuit as shown in figure 3-7. Withthis arrangement, flow through the heat source does

not change regardless of the flow proportions throughthe 3-way valve. Connections from the bypass circuit tothe remaining piping system are made using primarysecondary tees to prevent interference between the twocirculators.

3-way thermostatic valves supply the distributionsystem with a fixed water temperature regardless of theheating load. Under partial load conditions, the system

will overheat the building unless flow through the heatemitters is interrupted when the desired room temper-ature is attained.

A single 3-way thermo-static mixing valve thatcontrols water temper-ature to the distributionsystem does NOT protecta conventional boiler fromflue gas condensation.Figure 3-7 shows that aportion of water returningfrom the distributionsystem goes directly backto the boiler. When thedistribution systemoperates at low tempera-tures, this return waterwill cause sustained fluegas condensation in theboiler. This must beavoided.

One way to protect a conventional boiler fromsustained flue gas condensation is to install a second3-way thermostatic mixing valve as shown in figure 3-8. The additional valve monitors return temperature,and if necessary, mixes hot water from the boiler withcool return water from the return side of the primaryloop to boost water temperature entering the boiler.Some manufacturers even build this thermostatic valveinto their boilers.

Figure 3-8

Figure 3-7

27

3-5 3-way motorized mixing valves

3-way valve bodies can also be paired with precisionmotorized actuators. An electronic controller regulatessuch actuators. The resulting motorized valve systemcan supply either fixed or variable water temperaturesto a radiant panel.

The valve body used for this type of mixing system isoften different from that used for a 3-way thermostaticvalve. It has a rotating (as opposed to linear motion)shaft. As the shaft rotates through approximately 90degrees of arc, the internal spool simultaneously opensone inlet port and closes the other. This regulates theproportions of hot and cold water entering the valve,and thus determines the mixed outlet temperature.

The actuating motor turns the valve shaft very slowly.Rotating the shaft through 90 degrees of arc may take2 to 3 minutes. This slow rotation is not a problemgiven the slow response of many high mass distributionsystems. It actually helps stabilize the system againstovershooting or undershooting the target water temper-ature.

A temperature sensor attached to the piping leading tothe distribution system measures the mixed watertemperature leaving the valve. It provides feedback toan electronic controller that regulates the valve motor.If the temperature is exactly where it should be, themotor does not change the valve’s stem position. If thesupply temperature is slightly low, the motor veryslowly rotates the valve stem to allow more hot water to

enter the mix and vice versa. Since the sensor isdownstream of the valve’s outlet port, it providesconstant feedback to the controller allowing it to finetune water temperature.

The piping for a 3-way motorized valve is shown infigure 3-9.

Note the use of a boiler loop with a pair of closely-spaced tees to interface to the distribution system.This accomplishes two important functions. First, itprevents the boiler loop circulator from interferingwithin the flow through the 3-way valve. Second, itprovides another mixing point (shown as point B)allowing hot water in the boiler loop to mix with coolwater returning from the distribution system beforeentering the boiler.

The controller operating the valve motor senses bothsystem supply and boiler return temperature. Whennecessary, the controller can partially close the hot portof the 3-way valve to prevent the distribution systemfrom extracting heat faster than the boiler can produceit. This allows a single 3-way motorized valve to controlboth the supply temperature, and protect the boilerform low inlet temperature.

Most controllers used for mixing valves are able toprovide either setpoint or outdoor reset control. Thelatter cannot be accomplished (automatically) with 3-way thermostatic valves. A single 3-way motorizedvalve piped and controlled as described provides moreversatility than does a pair of 3-way thermostaticvalves.


Figure 3-9


28

3-6 4-way motorized mixing valves

Another mixing device that has seen extensive usage insystems pairing a conventional boiler and low temper-ature distribution system is a 4-way motorized mixingvalve. These valves were designed to provide bothsupply temperature control and boiler return temper-ature boosting. Figure 3-10 shows a cross section of atypical 4-way valve body.

Hot water from the boiler is mixed with cool returnwater from the distribution system at two locationsinside a 4-way valve. In the upper mixing chamber, thehot and cool water streams mix to form the streamsupplied to the distribution system. At the same time,mixing also occurs in the lower valve chamber. Herethe objective is to boost the temperature of the waterreturning to the boiler. As with motorized 3-way valvesystems, a temperature sensor mounted on the supplypipe to the distribution system provides feedback tothe valve controller. Another temperature sensormounted near the boiler return allows the controller tomonitor boiler inlet temperature. When necessary, thecontroller would partially close the hot inlet port to thevalve to prevent the distribution system from extractingheat faster than the boiler can produce it.

The recommended piping for a 4-way mixing valve isshown in figure 3-11. Closely- spaced tees are used toconnect the valve to the boiler loop. This prevents flowinterference between the boiler circulator and distri-bution circulator. The valve draws hot water from theboiler loop using the momentum of the flow returningfrom the distribution system. The boiler loop alsoensures adequate flow through the boiler under allconditions.

It’s important to understand that merely using a 4-waymixing valve body in a system does NOT guarantee thatthe distribution system will receive the proper supplytemperature. Neither does it guarantee the boiler isprotected from low inlet water temperatures. For propercontrol, the valve must react to both the supply andboiler return temperatures. To do so, it must be

Figure 3-11

Figure 3-10

29

directed by a controller that senses both supply andreturn temperature. It’s pointless to install a 4-wayvalve body while omitting the actuator / controller itneeds for proper operation.

3-7 Injection Mixing (the concept)

Injection mixing is one of the simplest yet mostversatile methods of controlling the water temperaturein a hydronic distribution system. The concept isshown in figure 3-12.

Hot water from the boiler loop is pushed through a pipecalled an injection riser. It enters the side port of a teeat point (A) where it mixes with cool water returningfrom the distribution system. The blending of these twostreams determines the supply temperature to thesecondary circuit. The greater the flow rate of hot waterentering the tee, the warmer the distribution systemgets and the greater its heat output.

Injection mixing is ideal for systems pairing a conven-tional boiler to a low temperature distribution system.The large temperature difference (∆T) between theincoming hot water and the outgoing return waterallows a high rate of heat transfer using a minimalinjection flow rate.

3-8 Injection mixing using a 2-way valve

One of the devices used for injection mixing control isa modulating 2-way valve. Either a non-electric thermo-static actuator or motorized actuator operates thevalve. The piping concept is shown in figure 3-13.

Hot water from the boiler loop is drawn into the supplyinjection riser at point B. It passes through theinjection control valve and enters the side port of a teeat point C where it mixes with cool return water fromthe distribution system. The flow rate through theinjection risers depends on the stem position of theinjection control valve, as well as the flow restrictorvalve’s setting. The greater the injection flow rate, the


Figure 3-13

Figure 3-12


30

higher the water temperature supplied to the distri-bution system and the greater its heat output. In atypical low temperature floor heating system suppliedby a conventional boiler, the flow rate through theinjection control valve is about 15 to 20% of the flowrate in the distribution system. This allows a relativelysmall modulating injection valve to regulate a large rateof heat transfer.

When a motorized valve operated by an electroniccontroller is used, boiler protection is accomplished bymonitoring the boiler inlet temperature and partiallyclosing the injection valve when necessary to preventthe distribution system from absorbing heat faster thanthe boiler can produce it.

Unlike a motorized valve with a “smart” controller, asingle thermostatic 2-way modulating valve cannotcontrol both the supply temperature to the distributionsystem and the inlet temperature to the boiler. Toprotect the boiler, it is necessary to use another mixingdevice that can monitor and adjust the boiler inlettemperature when necessary. Figure 3-14 shows theuse of a 3 way thermostatic valve for this purpose.

When using a 2-way valve for injection mixing, be surethe tees at points A and B in figure 3-13 are as closeas possible. Also be sure there’s a vertical drop of atleast 18 inches between where the return injectionriser connects to the boiler loop and where it connectsto the distribution system. This drop forms a thermaltrap to reduce heat migration into the distributionsystem when no heat input is needed.

It is important to select the injection control valvebased on its Cv rating, NOT the size of the injectionriser piping. Oversized injection valves will not producesmooth heat input control under low load conditions.Undersized injection valves will cause excessive headloss and may not be able to deliver design load heattransfer rates.

Before selecting the injection control valve, calculatethe necessary injection flow rate under design loadconditions using the following formula:

Where:

fi = required design injection flow rate at designload (in gpm)

Q = Heat input to distribution at design loadconditions (in Btu/hr)

T1 = water temperature being injected (in deg. F.)

T2 = water temperature returning formdistribution system (in deg. F.)

500 = a constant for water(use 479 for 30% glycol, 450 for 50% glycol)

Select an injection control valve with a Cv factorapproximately equal to the injection flow rate justcalculated.

Figure 3-14

fi = Q500 x (T1

_T2)

Formula 3-1

31

Once the system is operational, set the flow restrictorvalve so the injection control valve remains fully openat design load conditions. This allows the valve tooperate over its full range of stem travel as heat inputto the distribution system varies from zero to fulldesign load.

3-9 Injection mixing using a variable speed pump

Another method of injection mixing uses a small wetrotor circulator operated at variable speeds as theinjection device. The piping concept is shown in figure3-15.

Hot water from the boiler loop is drawn into the supplyinjection riser at point B. It enters the side port of a teeat point C, where it mixes with cool water returningfrom the distribution system. An equal flow rate of coolreturn water flows back from the distribution system tothe primary circuit through the other riser. The flowrate of hot water passing through the supply riser iscontrolled by the speed of the injection pump. Thefaster the pump runs, the faster hot water flows intothe distribution system and the greater its heat output.In a typical low temperature floor heating systemsupplied by a conventional boiler, the flow rate throughthe injection pump is about 15 to 20% of the flow ratein the secondary circuit. This allows a relatively smallinjection pump to control a large rate of heat transfer.

The injection mixing control also protects the boiler bymonitoring the inlet temperature and reducing thespeed of the injection pump when necessary to preventthe distribution system from absorbing heat faster thanthe boiler can produce it.

When using variable speed injection mixing, be surethe tees at points A and B in figure 3-15 are as closetogether as possible. Also be sure there is a verticaldrop of at least 18 inches between the (return)injection riser connection to the primary circuit and itsconnection to the secondary circuit. This drop forms athermal trap to reduce heat migration into the distri-bution system when no heat input is needed.

In a properly balanced system, the injection pumpshould run at full speed when the system is operatingat design load conditions. Achieving this balancerequires adjustment of the balancing valve located inthe return injection riser. There are several ways to setthis valve. One of the easier ways is to use a valve thathas built-in measuring capability. Many “circuit-setter”type valves are available for this purpose.

To properly set the circuit setter valve, it’s necessary tocalculate the required injection flow rate under designload conditions using formula 3-1. With the injectionpump running at full speed, partially close the circuitsetter valve until it indicates a flow equal to the valuecalculated.


Figure 3-15

SECTION

4

RADIANT FLOOR HEATING METHODS

The availability of modern materials such as Kitec pipe has allowed the market for hydronic radiant floor heatingto increase approximately ten fold over the last decade. Installation methods have been developed for manytypes of floor constructions in residential, commercial and industrial buildings. Each year these installationtechniques allow thousands of buildings to be equipped with what many consider to be the ultimate comfortheating system.

4-1 What is radiant heating?

Before discussing the installation details of radiant floor heating, it’s important to have a clear understanding ofhow radiant heating works as well as how it differs from other forms of heating.

Nature has three means of transferring heat from objects at a given temperature to objects at lower temperatures.

Conduction is how heat moves through solid materials, or from one solid material to another when the two are incontact. If you stand barefooted on a cool basement floor slab, heat transfers from your feet to the floor byconduction.

Convection is how heat moves between a solid surface and a fluid. The fluid may be either a liquid or a gas. Hotwater flowing through a pipe transfers heat to the inside wall of the pipe by convection. Likewise, air flowingacross the heat exchanger inside a furnace absorbs heat from the hot metal surfaces.

Radiant heat transfer occurs when infrared light leaves the surface of an object and travels to the surface(s) ofother cooler objects. Unlike conduction and convection, radiant heat transfer does not require a fluid or solidmaterial between the two objects transferring heating. It only requires a space between the two objects. Solarenergy travels approximately 93 million miles from the sun to the earth, through the emptiness of space, solelyas radiant energy. The radiant energy only becomes sensible heat when absorbed by a surface.

33


34

The radiant energy emitted by the relatively lowtemperature heat emitters used in hydronic heating istechnically described as infrared electromagneticradiation. It’s simply light that the human eye can’tsee. However, other than the fact that it’s invisible,infrared light behaves just like visible light. It travels instraight lines at the speed of light (186,000 miles persecond), and can be partially reflected by polishedmetallic surfaces. Unlike warm air, radiant energytravels equally well in any direction. Up, down orsideways, direction simply doesn’t matter. This charac-teristic allows a heated ceiling to deliver radiant heatto the room below.

The radiant energy emitted by a warm floor, wall orceiling is a completely natural phenomenon that’sliterally as old as the universe itself. A surface warmedby sunlight gives off infrared radiation just like onewarmed by embedded tubing. The latter simply uses adifferent heat source and transport system to deliverheat to the surface. Most low temperature radiantpanels emit less than 1/10 the radiant flux of brightsunlight, and all of it is infrared as opposed to ultra-violet light. Even the human body gives off infraredradiation to cooler surrounding surfaces.

4-2 The Benefits of Hydronic Radiant FloorHeating

Radiant floor heating is considered by many as theultimate form of comfort heating. In addition to theadvantages of hydronic heating in general, warm floorsprovide benefits that virtually no other system canmatch. Any one of these benefits can become the “hotbutton” that convinces a discriminating customer toinstall a hydronic radiant floor heating system. Here’s asummary of these key benefits.

Unsurpassed thermal comfort:

Buildings equipped with radiant flooring have interiorenvironments that are highly favorable to humanthermal comfort. Unlike many systems that directlyheat the air, radiant floor heating gently warms thesurfaces of objects in the room as well as the air itself.The warm surfaces significantly reduce the rate of heatloss from the occupants, allowing most to feelcomfortable at room temperatures 3 to 5 deg. F. lowerthan with other methods of heating.

The air temperature at floor level is slightly higher thanthe average room temperature. This significantlyreduces the rate of heat loss from the feet and legs.Several feet above the floor, the air temperature beginsto decrease. Most people tend to feel more alert withslightly lower air temperatures at head level. The lowestair temperatures in the room typically occur just belowthe ceiling. The result is reduced heat loss through the

ceiling insulation and hence lower heating costs.

A system that’s out of sight:

Most people realize that just about every occupiedbuilding in North America needs a heating system.However, few enjoy looking at the heat emitters that area necessary part of that system. The fact that such heatemitters often restrict furniture placement further addsto their invasiveness.

With hydronic radiant floor heating, the floor surface isthe heat emitter. There’s no need to compromise theaesthetics of the space or restrict furniture placement.It’s a system that gives your clients a building interiorthat’s as thermally luxurious as it is aestheticallyelegant.

A quiet system:

One of the strengths of hydronic heating is its ability todeliver heat without delivering noise. A properlydesigned radiant floor heating system is the epitome ofsilence. The gas or oil burner on the boiler is often theonly component that makes any detectable noise, andit’s usually located in the mechanical room away fromthe occupied spaces.

A clean system:

One of the biggest complaints associated with forcedair heating is its tendency to distribute dust, odors andgerms throughout a house. In contrast to whole houseair movement, hydronic flooring heating creates verygentle (imperceptible) room air circulation. Manypeople who suffer from allergies have found thatradiant floor heating doesn’t aggravate the symptomsthe way a forced air system often does.

A durable system:

A slab type floor heating system is nearly as indestruc-tible as the slab itself. It’s the ideal way to heat garagefacilities, industrial buildings, recreation rooms orother buildings with high interior traffic.

A system that reduces fuel usage:

Hydronic floor heating systems have a proven record ofreduced energy usage relative to other forms ofheating, both in residential and commercial / industrialbuildings. The savings result from several factors suchas the ability to sustain comfort at lower indoor airtemperatures, reduced air temperature stratification,non-pressurization of rooms (which leads to higherrates of air leakage), and the ability to operate withlower water temperatures.

Savings vary from one building to the next. Althoughsome projects have shown savings in excess of 50%, amore conservative estimate is 10 to 20% in savings.

As energy costs continue to escalate, the ability to

35

reduce fuel consumption will play an increasinglyimportant role in how heating systems are selected.Hydronic radiant floor heating can keep energy costs toa minimum while also delivering exceptional comfort.It’s truly the benchmark system against which all othermethods of heating will be compared.

4-3 The History of Hydronic Radiant Floor Heating

The origins of hydronic radiant floor heating date backto the early 1900s when systems were installed usingwrought iron and steel piping. During the 1940s and50’s, many radiant floor heating systems were installedby embedding copper tubing in concrete slabs.Although the installations were somewhat crude incomparison to today, these early systems quicklyproved they could deliver unsurpassed comfort.

Some of these early systems are still in operation.However, others have long since been abandoned dueto fatigue or corrosion of the embedded metal tubing.Although the comfort they delivered was exceptional,too many of the early systems using embedded copper,steel or iron pipe eventually developed leaks. Consumerconfidence in the thought that a hydronic floor heatingsystem could provide both comfort as well as a long,trouble-free service life steadily declined. The debut ofcentral air conditioning in the late 50’s, along withstrong promotion of forced air (ducted) systems as a“preferred” means of delivering both heating andcooling all but eliminated the use of hydronic floorheating. Or so it seemed.

Ironically, as the hydronic floor heating market wasnearing extinction in North America, a new tubingmaterial was being developed in Western Europe. That

material was cross-linked polyethylene (or PEX). Itwould soon prove to be the single biggest factor under-lying the reemergence of hydronic floor heating inNorth America.

Europeans had amassed considerable experience withPEX and PEX-AL-PEX tubing in floor heating applica-tions by the time these products made their firstappearances on the North American market in the early1980’s. Slowly but surely these modern pipingmaterials demonstrated they could deliver comfort,easy installation and long life. The rest—as they say—is history.

Today consumers are learning about new methods forinstallation of hydronic floor heating as never before.They are seeking qualified professional installers andquality products. Kitec pipe and WarmRite accessorieslet you give these discriminating consumers exactlywhat they’re looking for. Read on to see all the differentways these systems can be installed.

4-4 Slab on Grade Systems

As the past has demonstrated, concrete slab-on-gradefloors are ideal for hydronic floor heating. The numberof buildings with this type of floor construction is huge.It includes a significant percentage of single familyhouses as well as a large percentage of commercialbuildings. Some of the best floor heating opportunitiesare in “garage facilities” such as automotive servicecenters, town highway garages, fire stations andaircraft hangers. These buildings almost always haveuncovered concrete floors, and benefit tremendouslyfrom the warm, dry floors that hydronic floor heatingcan provide.

SECTION 4 RADIANT FLOOR HEATING METHODS

concrete slab

pipe

wire mesh

insulation

foundation

adhesivefinished flooring

vapor barrier

compacted fill

CONCRETE SLAB ON GRADE withunder slab insulation


36

Installation Procedure:

Figure 4-1 shows a cut-away view of a modern heatedslab-on-grade floor.

The installation of a heated floor slab begins byverifying the subgrade has been properly leveled andcompacted. Although the heating system installer isprobably not responsible for this aspect of

Figure 4-1

concrete slab

pipe

wire mesh

foundation


vapor barrier

compacted fill

CONCRETE SLAB ON GRADE withno under slab insulation

"chair"

max. 2" from surface

37

construction, failing to check for proper subgradepreparation could eventually compromise theembedded tubing circuits. It could also leave theinstaller having to defend why the floor heating systemisn’t at least partly responsible for cracks in the slab orother defects.

After the subgrade has been prepared, the soil vaporbarrier and underslab insulation should be installed.Some building specifications may not call for anunderslab vapor barrier. However, its ability to resistmoisture migration from the underlying soils can beindispensable, especially when wood products are usedas the finish flooring.

Heat loss from the edge and underside of a heated slabon grade can be substantial, especially in areas withhigh water tables or where the slab rests on bedrock.Edge and underslab insulation are essential inreducing these losses. They are a necessary part of anyquality floor heating system. Not taking steps tomitigate such heat loss is like leaving the windowsopen throughout the winter.

Realistically there’s only one opportunity to installunderslab insulation—before the slab is poured.Discovering high downward heat loss after the systemis in operation is a situation that’s virtually impossibleto correct. It makes little sense to attempt the instal-lation of a high quality heating system while omittingcrucial and relatively low cost details. Do it right thefirst time.

The most commonly used material for slab edge andunderside insulation is extruded polystyrene. It’s soldin 2 by 8 foot and 4 by 8 foot sheets in several thick-nesses. It’s also available in several densities to handledifferent floor loading. Extruded polystyrene panels arehighly resistant to moisture absorption, and have awell-established record in ground contact insulationapplications.

New insulating materials are developed to promote theuse of under slab insulation. One of them is calledradiant barrier foil. It is a composite of plastic andaluminum layers. The concrete Barrier Foils consists ofan aluminum layer sandwiched between two layers of“bubble” insulation. The “insulating” effect of thisnew product is comparable with the rigid foamproducts, but its handling and resistance tomechanical damage is far superior.

The amount of underside insulation depends on severalfactors. Among them are:

• The severity of the climate: colder climates justify edge- and underside insulation of greater R-value.

• The cost of energy: higher energy costs justify

edge- and underside insulation of greater R-value.

• The thermal resistance (R-value) of the floor covering(s): high thermal resistance coveringsjustify edge- and underside insulation of greater R-value.

• The shape of the slab: slabs with high ratios ofedge length to floor area justify edge- and underside insulation of greater R-value.

In most buildings the underslab insulation should havea minimum R-value of 5. In colder climates, it is oftenrecommended that the outer 4 feet of the slab (referredto as the “outer band”) have R-10 undersideinsulation. The insulation is generally omitted understructural bearing points such as beneath interiorcolumns or bearing walls.

The edge of the slab is especially vulnerable to heatloss. It should be insulated to a minimum of R-5 inmild climates and R-10 in colder climates.

The next step on most installations is to locate andtemporarily mount the manifold station(s). If one ormore of the manifold stations will be located within astud cavity, it’s imperative to make accurate measure-ments when fixing the manifold’s location.

The manifolds can be temporarily bracketed to aplywood panel supported on wooden or steel stakesdriven into the subgrade (as shown in figure 4-2)


Figure 4-2


38

Once the insulation is in place, the steel reinforcementfor the slab is installed. Most concrete slab on gradefloors use welded wire fabric (WWF) for reinforcementand crack control. WWF comes in sheets or rolls. Itshould be placed directly on top of the underslabinsulation. Edges should be overlapped approximately6” and tied together.

Tubing installation takes place one circuit at a time.Begin by securing one end of the circuit to the supplymanifold. Roll out the coil like rolling a “tire” followingthe layout pattern. The composite pipe, because of themetal content, allows laying the pipe roughly withouttying down immediately. This allows it to run the fullloop and get the end out to the manifold. Make surethe end reaches the manifold and then tie the pipingto the wire mesh. The main difference to laying PEXtubing is that the pipe stays in place and does not wantto go back to the coil shape.

This is why there is no need to use an uncoiler. If theuncoiler is available, it is also possible to lay the pipeusing it. In this case place the tubing coil on anuncoiler and pull the tubing from the coil as needed.Keep plenty of slack ahead of you as the tubing isfastened in place.

Kitec tubing should be secured to the WWF usingeither twisted wire ties or nylon pull ties. The tubingshould be tied to the WWF reinforcing every 60 to 72”on straight runs, and two ties at the bend on each side.

When all circuits have been installed, prepare themanifold(s) for pressure testing. Install a pressuregauge in one end of either the supply or returnmanifold and a schrader air valve in the other end. Plugthe unused manifold ends.

Use an air compressor to increase the pressure in thecircuits to about 100 psi. Use a soap bubble solutionto check for leaks at the manifold connections. Leavethe circuits pressurized for at least 24 hours. If the airpressure drops double check all manifold connectionsfor possible leaks before inspecting the tubing. Asidefrom the possibility of extreme damage from otherconstruction activity, it’s very unlikely that the tubing isthe source of the air leak. Still, a pressure test ismandatory on any radiant tubing installation.

If the WWF has to be positioned in the slab, be sure theconcrete placement crew knows to lift the tubing andWWF prior to starting the pour. If the WWF has to bepositioned within the slab, it has to be lifted or“chaired” up to the final position before the concreteis poured. The WWF and attached tubing should belifted up so the pipe center is 2” below the slabsurface. This allows the slab to respond faster whenwarm water circulates through the tubing.

From the heat output point of view, the position of the

piping in the slab is not so critical if full slab insulationis used. Appropriate thermal break will direct the heatflow towards the surface. If insulation is not used thepipe position is critical and in this case the piping hasto be lifted to 2” below the surface.

As long as the pipe is kept 2” below the surface sawcut control joints will not affect the pipe. If deeper than3/4” saw cuts are planned the pipe position has to beadjusted accordingly. Anywhere where full cut controljoints are used (slabs are separated) a protective sleevehas to be used on the pipe passing through. The sleevehas to be 12” long centered on the joint and approxi-mately 1” diameter. The sleeve reduces stress on thetubing should the slab move slightly at the controljoint.

4-5 Thin Slab Systems

There are several methods of installing hydronicradiant heating over a conventional wood-framed floor.One of the most common is called a thin slab system.The concept is shown in figure 4-3.

Thin slabs consist of either a specially formulatedconcrete or poured gypsum underlayment. Both typesof slabs have installation requirements that must becarefully coordinated with the building design process.

One requirement that must be accommodated is thatthin-slabs typically add 1.25 to 1.5 inches to the floorheight. This requires adjustments in the rough openingheights of windows and doors as well as the height ofdoor thresholds. It will also affect the riser heights onstairs.

Another issue that must be addressed is the addedweight of the thin-slab. Poured gypsum thin-slabstypically add 13 to 15 pounds per square foot to the“dead loading” of a floor structure. Standard weightconcrete thin slabs add about 18 pounds per squarefoot (at 1.5” thickness). Never assume the proposedfloor structure can simply support the added weight ofeither type of thin-slab. Have a competent designer orstructural engineer verify what, if any, changes arenecessary to support the added load.

The additional floor thickness and weight are easilymanaged if planned into the building as it is designed.However they can present obstacles in retrofit situa-tions.

Poured Gypsum Thin-slab systems

Poured gypsum underlayments have been used formany years for floor leveling as well as to enhance theacoustic and fire resistance properties of wood-framedfloors. They also function well as the slab material forthin-slab floor heating systems. In most cases, the slabis installed by a subcontractor trained and equipped to

39


gypsum slabpipe

under side insulation


sealant

floorjoist

subfloor

Figure 4-3


40

concrete slabpipe

underside insulation


polyethylene sheet

THIN SLAB ON WOOD FRAMED FLOORconcrete slab

floorjoist

subfloor

Figure 4-3A

41

mix and place the materials.

Installation Procedure

Installation begins by stapling the tubing to thesubfloor. A pneumatic stapler with a specialattachment allows the staples to be quickly placedwithout damage to the tubing. It’s the preferredattachment method for all but very small thin-slabareas.

Once all tubing circuits have been installed theyshould be pressure tested as described earlier.

Next the floor is sprayed with a combinationsealant/bond enhancement coating. This minimizeswater absorption into the subfloor as well as strength-ening the bond between the slab and subfloor.

The poured gypsum underlayment consists of gypsumcement, masonry sand, admixtures and water. Theproduct is prepared is a special mixer usually placedoutside the building, and is then pumped in through ahose. As the product is poured, it self-levels withminimum floating.

Some installers prefer to install the gypsum slab in twolayers (or “lifts”). This minimizes any differentialshrinkage in the slab, resulting is a very flat finishsurface.

When poured gypsum underlayment cures, itresembles plaster and is almost as hard as standardconcrete. However, unlike concrete it is NOT intendedto serve as a permanent “wearing surface.”

With the proper preparation, a poured gypsum slab canbe covered with almost any finish flooring includingcarpet, sheet vinyl, ceramic tile and glue-down woodflooring. Always follow the gypsum underlaymentmanufacturer’s procedures to verify that the slab isadequately cured that and the surface is properlyprepared before installing finish flooring.

Poured gypsum slabs are water-resistant not water-proof. The slab will eventually soften if exposed towater for prolonged periods. They should not beinstalled under conditions where rain or other sourcesof moisture can accumulate. They should also not beinstalled in areas that are likely to experience flooding.

Concrete Thin-Slab Systems

A specially formulated concrete mix can also be usedto create a heated thin-slab floor. The mix proportionsare given in figure 4-4

The installation of a concrete thin-slab differs consid-erably from that of a poured gypsum slab. Concrete isnot self-leveling. It must be screeded flat when placed.To simplify screeding, the concrete thin-slab is bestpoured before walls are constructed.

Unlike with gypsum underlayments, it’s crucial toprevent the bottom of the slab from bonding to eitherthe subfloor or any wall framing it may contact. Thegoal is to allow the wood floor deck and concrete thin-slab to move independently of each other during curingor seasonal moisture changes. This reduces tensilestresses that can crack the slab.

It’s also important to divide large floor areas into a gridof smaller areas using plastic control joint strips. Asthe concrete cures, cracks will develop directly abovethese strips. These “controlled” cracks preemptrandom cracking of the slab.

The slab should be cured for a minimum of 3 weeksprior to being heated. This allows time for the concreteto develop strength before being exposed to thermalstresses. To drive off any residual moisture, the slabshould also be operated (heated) for several days priorto installation of the finish floor.

With either type of thin-slab it’s imperative to installunderside insulation. When the space below the heatedfloor is also heated, use a minimum of R-11 undersideinsulation. If the space below the floor is partiallyheated, install a minimum of R-19 insulation. If thespace below the heated floor is an unheated crawlspace, install a minimum of R-30 underside insulation.Although these suggested underside R-values areconservative, the installer should verify they meet orexceed local energy code requirements.


Figure 4-4


42

The concept of thin slab installation can be usedretrofitting radiant floor heating to existing concretesurfaces. A thin over pour or topping pour is created onthe existing surface. Figure 4-4a shows the layers ofthe installation.

Ideally the new layer is separated with a thin layer ofinsulation. This will drive the heat upwards where weneed it and provide quick reaction time. Generally ½”

to 1” rigid foam is used. Using a vapor barrier ensuresthat no moisture gets into the heated layer. A new typeof insulation is also now available. Two layers of“bubble” insulation with aluminum foil in between hasa comparable insulating effect to the rigid foam. It alsoacts as a vapor barrier. The most difficult part whenlaying pipe on existing concrete is how to fasten thepipe. Individual clips can be used, though it is very

Figure 4-4a

concrete slabpipe


existing concrete

TOPPING POUR ON CONCRETE FLOOR

insulation

43

time and labor consuming. Special plastic staples orclips can be used when 1” foam is used as insulation.Another effective way is to use pipe track, sometimescalled rail fix, to hold the pipe in place. This 6.5 feetlong plastic channel is mounted to the floor at 3 points.The pipe clips into the side cutouts perpendicular tothe track.

1¼”-1½” thickness of smooth regular concrete ispoured to cover the pipe and create a very effectivethermal mass. There are no structural or strengthissues—the original slab takes care of that. The doorshave to be adjusted accordingly to accommodate thelevel increase.

4-6 Tube & Plate Systems

A concrete or gypsum slab acts as a “thermal wick” tohelp spread the heat releases from the embeddedtubing across the floor surface. However, there are

situations where slab installation is not an option. Insuch cases the heat dispersion can be provided byhighly conductive aluminum plates.

Kitec PEX-AL-PEX pipe is ideal for tube and plateapplications. Its rate of thermal expansion is very closeto that of the aluminum heat dispersion plates. Thisgreatly reduces the potential for expansion sounds asthe system warms and cools.

Figure 4-5 shows the general concept of a tube andplate system. Notice how the aluminum plates areshaped to fit the perimeter of the tubing. Heat trans-ferred from the tubing to the trough portion of the plateconducts out along the “wings” of the plate. Becausealuminum is an excellent heat conductor, theserelatively thin plates can disperse across the flooralmost as well as a slab yet at a tiny fraction of theweight and only about 1/2 the added floor height of athin-slab. They are a versatile component both for floorheating systems as well as radiant walls and ceilings.


pipe

plates used in joist space heating system(below subfloor)

finished flooring

heat transfer plate

THE CONCEPT OF TUBE & PLATE SYSTEMS

subfloor

pipeplates used with sleeper system

(above subfloor)finished flooring

heat transfer plate

subfloor

spacer (sleeper)

The heat is conducted to the plate from the pipeand spreads along the flat "wings". The large contactsurface evenly conducts the heat to the floor.

Figure 4-5


44

Above Floor Tube & Plate Systems

Figure 4-6 shows the installation of an “above floor”tube and plate system.

Here the tubing and plates are located on the top sideof the floor deck. The tubing can be run in virtually anydirection. The system can be adapted to several typesof finish flooring, and is particularly well suited fornailed down wood floor installations.

Figure 4-6

spacer(sleeper) pipe


finished flooring

SLEEPER SYSTEM ON WOOD FRAMED FLOORabove floor tube and plate

floorjoist

subfloor

heat transfer plate

45

Installation Procedure:

Begin by fastening 5/8” - 3/4” plywood or orientedstrand board (OSB) “sleepers” to the floor. Thesleepers are placed to create 3/4” wide grooves intowhich the tubing and trough portion of the plates arerecessed. To minimize any squeaks, the sleepers

should be glued as well as nailed (or screwed) to thesubflooring.

Grooves for the return bends, as well as other curvedtubing paths can be formed by routering out the 3/4”plywood or OSB. Another way is to place triangularshaped spacers to support the secondary floor layer at


spacer(sleeper) pipe


finished flooring

SLEEPER SYSTEM ON WOOD FRAMED FLOORabove floor tube

floorjoist

subfloor


46

curved areas.

The plates are set into the grooves with ends spacedabout 1” apart. Pull each plate against one edge of thesleeper and tack it in place with two or three lightgauge staples on the same side (and only on this side).This allows the plate to expand as the tubing is pushedinto it as well as when the plate heats and cools.

Then tubing is laid out and pushed into the grooves inthe plates. Stepping on the tube as it aligns with thegrooves ensures it is pushed all the way into the groove.

It is NOT necessary to install silicone caulking into thetroughs of the plates when installing Kitec PEX-AL-PEXpipe.

Above floor tube and plate systems are ideal whennailed-down wood flooring will be installed. Theflooring can be placed directly over the tube and plateswithout needing an additional cover sheet. The flooringshould be installed with its long dimension perpen-dicular to the tubing. Nails can be driven through theheat transfer plates, through the sleepers and into thesubfloor. Be careful not to drive nails through thetubing on return bends or other areas when the tubingis not visible as the flooring is laid. If the tubing needsto run parallel to the flooring at times, it is best to drilla shallow hole through the subfloor and route thetubing through the floor framing where it is protectedagainst nail punctures. The tubing can also be“plunged” beneath the subfloor and then routed upthrough the bottom plate of a partition to connect tothe manifolds.

For other types of flooring, it is necessary to install athin 1/4” or 3/8” cover sheet over the tube and platesto serve as a smooth stable substrate. Plywood is oftenused as the cover sheet under vinyl flooring or carpet.Cement board has also been used under ceramic tile.All tubing circuits should be pressure tested prior toinstalling the cover sheet. The tubing should remainpressurized as the cover sheet is installed. Be carefulnot to drive fasteners through the tubing when securingthe cover sheet.

The same concept of the sleeper system can be usedin low heat load installations, but without the heattransfer plates—mostly for floor warming systems.

The wood structure is a poor conductor of heat so thereis limited heat transfer sideways. The relatively thinlayer directly above the pipe will allow a lot more heatthrough than sideways. This results in large localtemperature differences depending on the position ofthe pipe. This effect limits the amount of heat that canbe transferred without creating high temperature“lines” on the floor surface.

The spacing used should be 6”-8” and again only a

limited amount of heat output can be provided. Toovercome this limitation, some manufacturers producepre-routed plywood sheets with aluminum layerattached to it to improve sideways transfer.

Below floor tube & plate systems

It’s also possible to fasten the tubing and aluminumheat dispersion plates against the bottom of thesubfloor. Below floor tube and plate systems work wellwhen raising the floor level is not an option. Theconcept is shown in figure 4-7.

The plate cradles the tubing against the subfloor aswell as disperses the heat across the floor to avoidobjectionable variations in floor surface temperatures.

The ideal installation conditions for this system wouldbe completely unobstructed floor joist cavities.However this is often not what the installer has to dealwith. In some cases, plumbing, electrical, ducting orother utilities may already be routed through the joistcavities. This could make access to the underside ofthe subfloor difficult or even impossible. Alwaysinspect the underside of the floor deck beforecommitting to a below floor tube & plate installationmethod.

47


Figure 4-7

pipe


finished flooring

heat transfer plate

JOIST SPACE HEATINGbelow floor tube and plate

floorjoist

subfloor


48

With a below floor installation, the tubing is pulled intoone joist cavity at a time and fastened up along withthe heat dispersion plates. The suggested installationsequence is depicted in figure 4-8.

The holes in the floor framing must be large enough forthe tubing to be easily pulled through.

As with thin-slab systems, it’s imperative to installunderside insulation. When the space below the heated

floor is also heated, use a minimum of R-11 undersideinsulation. If the space below the floor is partiallyheated, install a minimum of R-19 insulation. If thespace below the heated floor is an unheated crawlspace, install a minimum of R-30 underside insulation.Although these suggested underside R-values areconservative, the installer should verify they meet orexceed local energy code requirements.

Figure 4-8

THREADING pipe IN for joist space heating systems

Preparation:

Make a sketch of the floor surface and joists through which piping will be threaded and installed. Identify themanifold location and route to the manifold for each pipe loop.

Measure the length of the floor joist and multiply the joist length by two. This defines the footage of pipe perjoist cavity when floor joists are installed on 10" through 18" centers. When floor joists are on 10" through 18"centers, two runs of pipe are installed in each joist space. Three runs of pipe are installed in a joist spacewhen joists are spaced greater than 18" apart.

Calculate the number of joist spaces you can cover with the pipe coil length you are using. For example, if thejoist is installed on 18" centers and it is 20 feet long, multiply 20 x 2 to get 40 feet of pipe per cavity.Assuming a 300 foot coil length, 7 joists cavities could be covered. BUT, remember that you need to allow forthe length of pipe running from the manifold and back again. In this example and depending on the manifoldlocation perhaps only 6 cavities can be filled.

Pre-drill holes in the floor joists through which pipes will run. Two 1/2" pipes require a 1-1/2" diameter hole,while four 1/2" pipes require a 2" diameter hole. Holes should always be straight and aligned. Holes must bedrilled in the center of the floor joist and at least one foot away from the end of the joist support point.

This sketch shows the completed installationfrom below. The following figures lead usthrough a step by step process.

49


Pull pipe from the uncoiler and thread itthrough the pipe holes making a loop in eachbay. The loops needn’t be too long, leave justenough hanging from the joist that allowsyou to handle the pipe. Leave the pipe endhanging free in the last bay.

Move the slack from the first bay over to thesecond bay, then over to the third, fourth, etc.,until the last bay has enough pipe to run back tothe manifold and complete the pipe loop insidethe bay itself.

Keep moving the slack!

Return to the first bay. Pullenough pipe from theuncoiler to create a largeloop.


50

Use the pipe from the last bay and run itback to the manifold in the same joist holesas the loops. If the slack in the last bay isnot sufficient to run back to the manifold,feed more pipe from the uncoiler through thebays until the desired length is achieved.Attach the pipe to the manifold.

Ideally, you should leave enough pipehanging from the last bay to form the firstfinished section of the floor. Lift the pipeloop up into the joist space and beginfastening the pipe to the subfloor. Alwaysstart fastening the pipe on the side of theloop that runs back to the manifold. If morepipe is needed to complete the loop, it canbe fed from the neighboring joist space.

The slack in the last bay has disap-peared and the pipe is now attachedto the subfloor. Move back to the firstbay and pull more pipe from theuncoiler until a large amount of slackexists. Transfer this slack throughadjacent bays until it arrives in thesecond to last bay. Lift the slack upand fasten the pipe in this joist spaceas before. Continue this process untilall joist spaces are complete.

This process involves a good deal of pipe threading, but it eliminates pipe kinks and reduces stress on thepipe. Two people can work very effectively together with this installation method - one feeding pipe while theother fastens pipe in the joist space.

The installation is nearlycomplete! Once all bays arefinished, measure the distancefrom the first bay to the manifold.Cut the correct length of pipefrom the uncoiler making certainto leave enough pipe to connectto the manifold.

51


For joists installed on greater than 18" centers, three runs of pipe are required in each joist space. The pipehandling and installation technique is similar in concept to that described in steps 1 through 8. Create pipeslack and transfer the slack to adjacent bays as before. Note in the following sketch however, that pipe entersthe bay at one end of the joist and exists at the opposite end in order to accommodate three runs of pipe.


52

4-7 Suspended tube systems

The ability of Kitec PEX-AL-PEX piping to handlerelatively high water temperatures makes it possible toinstall a suspended tube system as depicted in figure 4-9.

The tubing is placed within the air cavity between thefloor joists. The tubing gives off direct radiant energy tothe surfaces within the joist cavity. The outside of thetubing also gives off heat to the surrounding air, estab-lishing a gentle convective circulation within the joistcavities. The warm air flows across the underside of thesubfloor transferring more heat to it.

Suspended tube systems have some unique benefits.They don’t require heat dispersion plates and thusreduce installation cost. They operate at high watertemperatures under design load conditions and thuscan often be piped directly to a boiler without needinga mixing valve. When the tubing is suspended belowthe subfloor, it is not subject to puncture from the nail

points associated with installation of hardwoodflooring.

Kitec PEX-AL-PEX piping is ideal for suspended tubesystems. Its aluminum core provides the structure thatprevents the tubing from sagging between supportswhen operated with high water temperatures.

As with all floor heating systems, it’s imperative toinstall underside insulation.

This must be a reflective insulation system meaningthat there is a shining reflective metal surface facingthe pipe. There has to be an air gap between the pipeand the reflective layer minimum 2” or more.

Foil faced batting insulation or the aforementioned“bubble” insulation can be used. The “bubble”insulation is different from the one used with concrete.The aluminum layer is exposed on one side minimumand is always facing the piping. The insulating layercan be one or two layers of plastic “bubble” dependingon the amount of insulation required.

Figure 4-9

53


When the space below the heated floor is also heated,use a minimum of R-11 underside insulation. If thespace below the floor is partially heated, install aminimum of R-19 insulation. If the space below theheated floor is an unheated crawl space, install aminimum of R-30 underside insulation. Although thesesuggested underside R-values are conservative, theinstaller should verify they meet or exceed local energycode requirements.

Threading the pipe into the joist space is identical tothe method explained under the section discussingjoist space heating with heat transfer plates.

The fastening of the pipe is different in this case. Thereare three main ways to secure the pipe; stapling to theunderside of the subfloor; using a pipe hanger tosuspend the pipe in the joist cavity; or use a nail clipto nail the pipe directly to the side of the joist.

Stapling to the floor is very simple, however the pipe isclose to the surface and can be punctured easily fromabove. The other two overcome this problem, but an

extra item pipe hanger or nail clip is used.

In high heat load installations, the direct stapling tothe underside can result in high and low temperature“lines” on the floor.

The fastest and easiest to install is the nail clipmethod. They all have their advantages and disadvantages.

It’s possible to staple Kitec pipe directly against theunderside of the subflooring without using heatdispersion plates. As discussed above this approach isonly suggested for low heating load situations such asrooms that have minimal if any exterior exposure.Without either a slab or aluminum heat dispersionplates, the floor’s ability to spread the heat laterallyaway form the tubing is more limited. Still, when thedesign heat load of the space doesn’t exceed 15Btu/hr/sqft, this installation method can deliveradequate heat output at reasonable water temperatures.

pipe


finished flooring

JOIST SPACE HEATINGbelow floor tube stapled

floorjoist

subfloor

reflective layer min. 2" air gap

pipe in pipe hanger


finished flooring

JOIST SPACE HEATINGbelow floor tube suspended

floorjoist

subfloor

reflective layermin. 2" air gap

pipe hanger


54

pipe in pipe hanger

underside insulation stapledinside the joist cavity

finished flooring


floorjoist

subfloor

reflective layer min. 2" air gap

pipe hanger

Reflective foil insulation (aluminum-bubble)

pipe in pipe hanger

under side insulation stapledto the bottom of the joists

finished flooring


floorjoist

subfloor

reflective layer

pipe hanger

Reflective foil insulation (aluminum-bubble)

pipe mounted with nail clip


finished flooring

JOIST SPACE HEATINGbelow floor tube clipped to joist

floorjoist

subfloor

reflective layer

min. 2" air gap

1"- 2" distance from floor

55


In this chapter, we pointed out the effects of the floorconstruction method on the radiant floor heatingsystem. As a summary, it is probably fair to say thatpiping can be fitted into any floor surface and there arenumerous variations to fit the project circumstances. Itshould also be clear that there are important differ-ences between these methods and some are bettersuited than the other for effective heat transfer.

The following image (figure 4-10) illustrates the heattransfer process during joist space installation usingheat transfer plates or direct staple up.

The image speaks for itself and gives very good reasonsto consider using the heat transfer plates wherever it ispossible.

Figure 4-10

Comparison of floor surface temperatures with and without heat transfer plates for 1/2" tubing8" o.c., operated at 100ºF and 140ºF water temperatures

SECTION

5

RADIANT WALLS AND CEILINGS

Although the majority of hydronic radiant heating systems are installed in floors, the walls and ceiling of a roomcan also make excellent radiant panels. This is possible because radiant energy travels equally well in anydirection. Just as visible light travels downward and sideways from a ceiling fixture to illuminate the surfacesbelow, infrared light (e.g. radiant heat) will travel to warm the objects in the room below.

Experience with hydronic ceiling heating in North America dates back to the 1940s. Many systems were installedusing both copper and iron tubing embedded in “plaster on lathe” ceilings. These systems demonstrated thatradiant ceiling heating is not only feasible, but also able to create excellent comfort conditions. Some of thesesystems are still functioning today.

5-1 Advantages of Radiant Walls and Ceilings

Hydronically heated walls and ceilings offer several unique advantages compared to one or more of the floorheating options discussed in section 4. In circumstances where floor heating is not possible due to floor coveringselections, heating load requirement (or other considerations) a heated wall or ceiling may be an ideal alternative.Keep the following advantages in mind as you evaluate your installation options.

• The output of heated walls and ceilings is not affected by floor coverings or furniture. Even a heated floor that’s initially installed with a low resistance covering may, at some future date, get covered with ahigh resistance finish floor that could substantially reduce its heat output. Most walls, and in particular ceilings, are unlikely to get more than a few coats of paint over the life of the system.

• Rooms such as bathrooms and kitchens often have a significant portion of their floor area occupied by base cabinets, islands, appliances or other objects that prevent the underling floor from being an effective heat emitter. In contrast, the ceilings of such spaces usually provide a virtually unobstructed surface from which radiant heat can be emitted. A radiant ceiling will also warm the countertop, floor

57


58

and tub surfaces below.

• In rooms where prolonged foot contact with the floor is likely, the maximum floor surface temperature should not exceed 85 deg. F. Thislimits the heat output from a heated floor to 35 to 40 Btu/hr/sq. ft. However, this temper-ature limit does not apply to heated walls and ceilings. A heated ceiling 8 feet above can be operated at temperatures as high as 100 deg. F. A 9 ft. tall ceiling can be operatedas high as 110 deg. F. At these surface temperatures, heat outputs in excess of 70 Btu/hr/sqft are possible from either a heated wall or ceiling. Because of the higher outputs, the area of the radiant panel can often be reduced. This in turn reduces installation cost.

• Heated walls and ceilings typically have very low thermal mass and can respond quickly to changing load conditions. This is especially advantageous in rooms with significant solar gains or other sources of internal heat. This fast response is also beneficial for spaces thatneed to be quickly restored to normal comfort after prolonged setback periods.

• Heated walls and ceilings typically add very little weight to the structure and thus don’t require structural alterations.

• Heated ceilings usually require less vertical space than most types of floor heating insta-lations. This may be a significant advantage inretrofit situations, especially in basements with limited head room.

• Heated ceilings create very little air distu-bance in the room below. Approximately 95% of the output from a heated ceiling is in the form of radiant energy. Very little convection iscreated. The reduced air movement is especially desirable in rooms where dust movement and drafts need to be avoided.

• A radiant wall is an excellent addition to a walk-in shower. The warmed surface greatly improves the comfort over that of cold tile surfaces, especially if one or more walls are exposed to outdoor ambient conditions. The heated wall can be used to supplement the output of a heated floor. It also helps dry the shower walls quickly after a bath.

• Radiant walls make an excellent supplement to floor heating for indoor pool enclosures. In many cases, the amount of floor area availableis limited due to the size of the pool. A low profile radiant wall will not only supplement the heat output, but will also significantly

improve the comfort and help dry water splashed on the wall.

5-2 Radiant Wall Construction

Radiant walls can be constructed using a variation ofthe tube and plate system described in section 4.Figure 5-1 shows how the components go together.

In most rooms, it’s neither necessary nor desirable toheat an entire wall from floor to ceiling. A betterapproach is to heat a low “perimeter band” along thewall. The heated area may extend 3 to 4 feet above thefloor. This approach tends to direct the radiant energyinto the lower (occupied) portion of the room.

A perimeter band can often be planned to run beneaththe windowsill level to keep the tubing layout simple.Since the tubing is only installed in the lower portionof the wall, there’s much less chance of it being struckby a nail (such as when a picture is hung on the wall).A “chair rail” molding often provides a convenientarchitectural divider for a transition between theheated lower portion of a wall and the unheated upperportion.

Installation:

If the tube and plates will be installed on the insidesurface of an exterior wall, be sure that the wall is wellinsulated. To keep the outward heat loss comparable tothat of a non-heated wall, the R-value of the wallinsulation should be increased by about 50%. A vaporbarrier should also be installed on the warm side of theinsulation.

If the tube and plates will be installed on an insidepartition, an R-11 fiberglass batt or other insulationwith equivalent R-value should be installed behind thetube and plate system to steer the heat in the desireddirection.

Begin by ripping 3/4” plywood sheets into strappingboards. The strapping boards, shown in figure 5-1,should have width 3/4” less than the tube spacing tobe used. They can be nailed or screwed to the wallframing leaving a 3/4” gap between each adjacent row.These gaps accommodate the tube and trough portionof the heat dispersion plates.

Most walls require electrical outlets. When the wall willbe clad with a tube and plate system, the junction boxmust extend an additional 3/4” out beyond the face ofthe wall studs to accommodate the added thickness ofthe strapping. It’s usually easiest to install thenecessary junction boxes before fastening the 3/4”plywood strapping to the wall. The tubing andaluminum heat dispersion plates should be kept atleast 2” away from the junction boxes to minimize heattransfer to the box and the electrical device it contains.

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Where the tubing needs to form a return bend, hold thestrapping short of the end of the wall by a distanceapproximately equal to the radius of the tube bend. A1.5” x 3/4” plywood strip should be installed at theends of the wall as a solid surface to which the wallfinish can eventually be fastened. Be sure to planwhere the tubing will enter and exit the wall. Figure 5-2 shows these details.

After the strapping is installed, the aluminum heatdispersion plates can be set in place and tacked using2 or 3 staples through one wing of the plate. Be sureto pull the trough portion of the plate to one side of thestrapping before stapling it. This creates a slight gapon the other side of the trough allowing the plate toexpand slightly as the tube is pressed in place. Leave

a gap of approximately 1 inch between ends ofadjacent plates.

Uncoil the Kitec pipe and press it into the plates. Besure to leave enough slack at the beginning and end ofthe serpentine pattern to connect the circuit to amanifold. A rubber-faced mason’s float makes anexcellent tool for tapping the tubing into the plateswithout denting them.

After the circuits have been pressure tested, the wallcan be covered with drywall or other panels. If the wallis to be finished with ceramic tile, the tubing andplates can be covered with a layer of cement board.The tile would then be bonded to the cement boardwith thin set mortar. Be sure not to drive fastenersthrough the tubing when installing the wall covering.

SECTION 5 RADIANT WALLS AND CEILINGS

Figure 5-1


60

vapour barrier

Figure 5-1A

61

5-3 Radiant Ceilings Construction

The same tube and plate system used for a heated wallcan also be used to create a radiant ceiling. Essentiallythe whole system is simply rotated by 90 degrees. Theconcept is shown in figure 5-3.

Installation:

Again, it is suggested that any electrical boxes on theceiling be installed with an additional 3/4” projectionbelow the ceiling framing prior to installing thestrapping.

After the strapping is installed, the aluminum heatdispersion plates can be set in place and tacked using2 or 3 staples on one side of the plate. Be sure to pullthe trough portion of the plate to one side of thestrapping before stapling it. This creates a slight gapon the other side of the trough, allowing the plate toexpand slightly as the tube is pressed into place. Leavea gap of approximately 1 inch between ends of

adjacent plates.

Uncoil the Kitec pipe and press it into the plates. Arubber-faced mason’s float makes an excellent tool fortapping the tubing into place without denting theplates. The slightly overbent shape of the heatdispersion plates will hold the tubing up after it ispushed tightly into place.

After the circuits have been pressure tested the ceilingcan be drywalled. Leave some air pressure in thetubing as the drywall is installed. Because of theplywood strapping, additional screws and nails can beused if necessary to ensure the drywall is pulled tightlyagainst the tubing and plates. Snap a chalk linehalfway between the rows of piping and install thedrywall fasteners along it. Be especially careful not todrive fasteners through the tubing near the returnbends.

SECTION 5 RADIANT WALLS AND CEILINGS

Figure 5-2


62

Figure 5-3

Figure 5-3A

SECTION

6

MANIFOLD SYSTEMS

6-1 Introduction

The vast majority of new hydronic radiant heating systems use one or more manifold stations as the connectingpoints for the tubing circuits.

All manifold stations consist of a supply manifold and a return manifold. The manifold station might be equippedwith trims such as valve actuators, circuit flow meters, isolation valves and venting/draining components. Thenecessary trim is determined by how the system is intended to operate. For example, it’s possible (although notalways necessary) to operate each radiant panel circuit on the manifold station as an independent zone. A tubingcircuit that heats the floor of the master bathroom could operate while the circuit(s) serving the bedroom adjacentto it remain off.

This section discusses the various manifold systems available from IPEX and suggests where each is appropriate.

6-2 Zoning Considerations

Hydronic heating has long been known for its ability to provide heat precisely when and where it’s needed. If thebuilding occupants desire a bathroom maintained at 75 deg. F., a child’s bedroom at 65 deg. F., and an unusedguest room at 55 degree F., hydronic heating can easily accommodate their needs.

Before planning the location of manifold stations, decisions need to be made on how the areas will be zoned.

One option is to treat the entire building as a single zone. This is appropriate when the following conditions are met:

• The occupants want to keep all rooms at similar and constant (although not necessarily identical) temperatures.

• All rooms have similar internal heat gains from sunlight, equipment, people and other sources.

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• If temperature setback is used, all rooms will operate on the same setback schedule.

• There is relatively good air flow between rooms. The doors between individual rooms and interconnecting spaces are left open mostof the time.

If these conditions are met, the entire building couldbe controlled as a single zone using a single thermostat(or other type of interior air temperature sensor). Sincethe control hardware is minimized, this approach willreduce installation cost.

When the conditions described above are not met, it’sappropriate to plan the system for multiple zones.

When planning for multiple zones consider thefollowing:

• What group of areas (if any) tend to have similar temperature requirements at the same time of day. For example, a home may have two or more bedrooms that are unoccupied during the daytime and thus could be kept at a reduced temperature to reduce fuel usage.

• What areas have similar internal heat gain patterns. For example on sunny days some rooms may receive enough direct solar heat gain to offset most of their heating load, even when it’s very cold outside. A properly zoned system should allow the heat input from the hydronic system to these rooms to stop under such conditions. At the same time, other roomsthat don’t experience these heat gains should receive the necessary heat input to maintain their set temperatures.

• What areas have heat emitters with similar thermal mass. A room with a higher thermal mass system such as a heated concrete slab will not warm nor cool as fast as an otherwise identical room heated by fin-tube baseboard. If these two rooms were on the same zone, and that zone was operated with a temperaturesetback strategy, or experienced significant solar heat gain, the two rooms cannot respond comparably. The room heated by fin-tube baseboard could quickly interrupt heat input when solar heat gains occur, while the room with the heated slab would likely overheat dueto the significant amount of heat stored in theslab.

A common misconception about zoning:

Some heating system designers feel that every roomthat may, at some point, need to be at a temperaturedifferent from that of other rooms, must be operated asan independent zone with its own thermostat. This is

not true. It’s possible under the right circumstances tomaintain rooms at different air temperatures eventhough they are grouped together as a single zone andoperated by a single thermostat.

One way to accomplish this is through the heat outputcapacity of the heat emitters. Imagine two identicalrooms that have the same heating load. One has 10feet of baseboard; the other contains 12 feet of thesame baseboard. Water at the same temperature issupplied to both baseboards at the same time.Obviously there will be greater heat output into theroom with the longer baseboard and thus it will attaina higher air temperature under all load conditions.

In the case of radiant panel heating, the output of thepanel at a given water supply temperature can bealtered by changing the amount of pipe used in thefloor. The easiest way to achieve this is to vary the tubespacing. Again, imagine two identical rooms with aheated slab floor. In one room the tubing is spaced 9inches on center. In the other the tubing is spaced 12inches on center. Assuming both rooms are suppliedwith the same water temperature at the same time, theroom with the closer tube spacing will receive moreheat input and thus attain a higher air temperature.

Another method of controlling heat output, one thatcan be adjusted once the heat emitters are installed, isby varying the flow rate through individual heatemitters. Once again imagine two identical rooms withidentical heating load, and identical heat emitters.Both rooms are controlled from a single thermostat,and have the same supply water temperature whileoperating. If the flow rate through one baseboard isreduced using a balancing valve, the average watertemperature in that heat emitter will decrease as willits heat output. Thus the room operated at the lowerflow rate will stabilize at a lower air temperature.

Understanding the above concepts and applying themwhen appropriate can reduce system costs. It alsodoesn’t mandate the installation of individual roomthermostats when they are not necessary.

6-3 Type of Manifolds

Manifold stations can be constructed using eithervalved or “valveless” manifold components.

Valved manifolds are either supplied with a shut-offvalve for electrical actuator or balancing valve for eachconnected circuit. The valves allow the flow ratethrough individual tubing circuits to be adjusted, orcompletely stopped if necessary. Valveless manifolds,as their name implies, do not have this capability. Theyserve solely as a header for the attached circuits.

In situations where individual flow control of each

65

circuit is desired a valveless manifold is installed asthe supply manifold where each tubing circuit begins,and a valved manifold is installed as the returnmanifold where each circuit ends. This allows theoptimal flow direction through the manifold valves.

Figure 6-1 shows a 4-circuit valved as well as valvelessmanifold.

Valveless Manifold Systems

There are radiant panel heating applications where“valveless” manifold systems are well suited.Recognizing such situations often allows the installedcost of the system to be reduced.

An appropriate application for valveless manifolds iswhen a large building area is to be heated as a singlezone. The large area requires several tubing circuitsthat all operate at the same time with the same supplywater temperature. Provided that circuit lengths arekept within 10% of the same length, such circuits canbe connected to a single valveless manifold.

The designer should recognize that circuits connectedto valveless manifolds cannot be individually balancedor isolated. They also must be purged simultaneouslywhen the system is filled. The designer should ensurethat adequate means of high capacity purging areprovided for each valveless manifold station. In mostcases, the advantage of being able to isolate and shutdown the loops far outweigh the cost saving by usingvalveless manifolds.

A valveless manifold can also be combined with a zonevalve as shown in figure 6-2 when several circuits areto be controlled from a single thermostat. This optionis less expensive than installing several valve actuatorson individual circuits and controlling them as a group.

Valved Manifold Systems

In many hydronic systems including those supplyingradiant panels as well as other types of heat emitters,the flow resistance of each connected circuit can varyconsiderably. For example, in the case of radiant floorheating, one tubing circuit my be 60 feet long whileanother, connected on the same manifold, may be 300feet long.

If such circuits are connected to a valveless manifoldstation, the flow rates will be higher in the shortercircuits. This may not allow sufficient heat delivery inthe areas served by the longer circuits.

A manifold station with circuit balancing valves oneither the supply or return manifold allows the flowresistance of each circuit to be adjusted. This helpsensure that each circuit delivers the proper flow rate toits heat emitter.

Valved manifolds also allow the possibility of individ-ually controlling each attached circuit. The mostcommon approach is to attach an electric valveactuator to each valve bonnet on the manifold as shown

SECTION 6 MANIFOLD SYSTEMS

Figure 6-1 Figure 6-2


66

in figure 6-3. As it’s screwed onto the manifold valve,the actuator pushes the valve’s stem to its fully closedposition. When low voltage (24VAC) is applied to theactuator it retracts its stem allowing the spring insidethe valve body to open the valve’s plug.

The valve opens to its full position. The flow balancingis set on the balancing valve on the other manifold.

There are manifold types where the travel of the valvestem can be adjusted. The manifold valve only opensto its set balancing position when the actuator ispowered up. This allows the valve to provide the properbalancing for the circuit when it’s open as well as ameans of on / off flow control when an actuator isattached.

In summary, the following manifold variations are usedin hydronic systems;

Plain manifold

Manifold with plain shut off valves

Manifold with provision for electrical valve actuator

Manifold with flow rate indicator

Manifold with balancing valve

Manifold with balancing valve and flow rate indicator built-in

6-4 Locating Manifold Stations

The number and placement of manifold stations in abuilding depends on the following:

• Will all floor circuits operate at the same supply water temperature? A given manifold station can only supply one water temperature to all its circuits at one time. If the system requires more than one supply water temper-ature at a given temperature, it will need at least two manifolds (one for each water temperature).

• Can all floor circuits be routed from a single manifold without excessive “leader” lengths? Leader length is the portion of the circuit

Figure 6-3

67

between the manifold station and the room where the circuit will release most of its heat. Such lengths should be kept to a minimum.

• Is the diameter of the manifolds sufficient to handle the entire system flow? To avoid noise and possible erosion due to high flow velocities,a 1" manifold should generally be limited to 11 circuits, and a 1.25" manifold limited to 15 circuits. Projects with a high number of circuits are usually better served by designing for multiple manifold stations.

• What locations are available for manifold stations? Manifold stations can be mounted both horizontally and vertically. In either case it is imperative to provide access to the manifold station. Try to avoid locations where furniture or other heavy or difficult to move objects would block such access. Try to find locations where the manifold access panel does not detract from the interior aesthetics ofthe building. In buildings with public access, the manifold stations are generally provided with “lockable” enclosures, or are located in areas where only authorized personnel have access.

• How many floor levels does the building have?It’s often convenient to provide at least one manifold station on each floor level of a building. The reason is to minimize leader length in tubing circuits.

• Will some circuits be filled with an anti-freeze solution while others operate with water? Circuits operating with anti-freeze solutions must be supplied through different manifolds than those operating on water.

Whenever possible, manifold stations should belocated so that circuits can be routed away from themin several directions. This typically reduces the lengthof circuit leaders.

In buildings with wide, spreadout floor plans, it isusually better to install two or more manifold stations(each with circuits clustered around it) rather thanattempting to route all circuits back to a singlelocation. The latter approach tends to create situationswhere tubing is closely packed along hallways thathave very low heating requirements. Figure 6-4 showsan example of what can happen when the manifoldstation(s) are poorly placed. Note the concentration oftubing down the hallway.


Figure 6-4


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Manifold Mounting

Manifold stations are often mounted within the hollowcavity between wall studs. The lower manifold shouldbe mounted 1.5 – 2 feet. The top manifold should be2.5 – 3 feet above the floor to allow some flexibility inthe tubing from where it penetrates the floor surface towhere it connects to the manifold.

It’s important that tubing penetrates the floor surfacewithin the stud cavity. In the case of slab systems, thestud cavity doesn’t exist at the time the manifoldstation is placed. Accurate measurements are essentialto making sure the tubing penetrations remain insidewhere the wall will eventually be located.

For slab type floor heating systems, some installersmake a wooden tubing template block that aligns thetubing where it penetrates the slab surface with themanifold connections above. The template block is

supported on two driven stakes. The top of the blockshould be set at the same elevation at the top of theslab. The template block is typically the same width asthe wall framing and remains in place after the slab ispoured.

Other installers erect a temporary support for themanifold stations as shown in figure 6-5. This allowsthe tubing circuits to be connected to the manifoldstations for pressure testing prior to the pour. After thewalls are framed, the plywood backer can be removedand the manifold brackets secured to permanentframing.

All tubing should be sleeved where it enters and exitsa slab surface. The sleeving protects the tubing fromtrowel edges when the slab is finished, as well as fromother physical damage over the life of the system.

When the manifold station is to be mounted within a

Figure 6-5

69


wall framing cavity, that cavity must be suffi-ciently deep. A 2x4-framed wall with a studthickness of 3.5 inches is a bare minimum. A2x6-stud cavity 5.5 inches deep provides aneasier installation. The installer might also lookfor the opportunity to “fur out” the interior wall ofa closet to provide a deeper mounting cavity.

The manifold mounting brackets should besecured to a solid wall, or a plywood panel thatitself is secured directly to framing.

Be sure to make the access opening large enoughto install valve actuators if they are planned atthe present or may be added in the future.

Manifold stations can also be mounted horizontally. Agood example is a manifold station secured to theunderside of a framed floor deck as shown in figure 6-6.Tubing circuits from a thin-slab or tube & plate floorheating system can drop down through the sub floorand connect to the manifold station. Mounting one ormore manifold stations to the underside of a framedfloor with access from the basement eliminates theneed for access panel in the finished space above.

6-5 Manifold Piping Options

When multiple manifold stations will be operated atthe same supply temperature, they should be piped inparallel as shown in figure 6-7.

Never connect multiple manifold stations in series witheach other. The resulting pressure drop would be verylarge. The downstream manifold would also operate ata lower temperature and greatly reduced heat output.

Good hydronic piping design encourages the instal-lation of valves that can isolate major system compo-

plywood panel

manifold station

floor joist

route tubing through shallow holes in subfloor

plywood subfloor

topping pour

supply

return


Figure 6-7

Figure 6-6


70

nents from the balance of the system should theyrequire service. Installing a pair of full port ball valveson the supply and return side of each manifold stationto provide such isolation is considered good practice.IPEX offers such valves that thread directly to themanifolds.

IPEX manifolds can be configured with adaptersallowing them to be supplied using either coppertubing or large diameter Kitec pipe. Distribution pipingfor multiple manifold systems can be set up severalways depending on the flow requirements and routingrequirement. These methods include:

• Trunkline piping

• Homerun distribution piping

• Parallel primary / secondary piping

The concept of trunkline piping is shown in figure 6-8.Each manifold station taps into a common supply(trunk) pipe as well as a common return (trunk) pipe.Because this is a form of parallel piping, each manifoldstation receives the same water temperature (assumingminimal heat loss along the trunk piping).

Trunkline distribution piping can be constructed of

Figure 6-8

71

either rigid metal pipe or larger diameter Kitec pipe. Itcan be routed through the framing cavities of thebuilding, in a mechanical chase above the ceiling, oreven under the floor slab. In the latter case, flexibleKitec PEX-AL-PEX or PEX tubing is recommended.Portions of the trunkline piping may need to beinsulated to minimize heat transmission to floor areasen route to the farther manifold stations. The size ofthe supply trunkline pipe can generally be reduced asflow is removed at each manifold station. Likewise, thepiping size of the return trunkline is usually increasedas return flow is added at each trunkline. The flowvelocity at any point in the trunkline piping should not

exceed than 4 feet per second to minimize flow noise.

Another option is to pipe each manifold as a“homerun” circuit as depicted in figure 6-9. A headeris the mechanical room handling the supply and returnflow to each manifold station. Homerun systemsgenerally use small tubing than trunkline systems.Smaller diameter Kitec PEX-AL-PEX or PEX tubing iseasier to route through confined building cavitiessmaller tubing, especially in retrofit applications.Homerun systems are another form of parallel pipingand thus deliver the same water temperature to eachmanifold station.


Figure 6-9

6-6 Manifold Accessories

IPEX also offer manifolds with built-in flow indicators /balancing valves. They allow the flow in each circuit tobe read as well as adjusted. When a manifold with flowindicators / balancing valves is used, it should beinstalled as the return manifold. A valveless manifoldcan be used on the supply side. If valve actuators willalso be installed, the other manifold must be valved to

accommodate the loop valve actuator.

Manifold stations can also be equipped with air ventingoptions as well as fill/drain valves. A float type air venton the top manifold assists with air removal when thesystem is filled. When fill / drain valves are installedeach manifold station can be individually purged.These accessories are shown in figures along thischapter.


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Another method of supplying multiple manifoldsystems with the same water temperature isprimary/secondary piping. Figure 6-10 depicts theconcept.

Note that each manifold station now has its own circulator. This circulator can be smaller than a singlecirculator that provides flow to the entire distributionsystem and all manifold stations. It can also beindependently controlled if necessary.

A pair of closely spaced tees connects the manifold

riser piping to a crossover bridge in the primary loop.This detail allows any of the manifold circulators tooperate without interference with the circulator in theprimary loop.

The use of primary/secondary piping to supply multiplemanifold stations is generally not necessary inresidential and light commercial systems. However, itdoes provide an option to a large central pump andnumerous control valves in larger industrial systems.

See more details of piping systems in chapters 8 and 9.

Figure 6-10

SECTION

7

PRE-ASSEMBLED CONTROL PANELS

7-1.1 General

There is an endless variety of design options for hydronic systems. Every installation is designed as a specificproject using a combination of pipe, manifolds and individual components to construct a heating system.

Depending on the project specifications and features and factoring in individual preferences, even similarprojects can show major variations in design and components. Despite this, it is possible to find similarities andcreate "standard" assemblies that are versatile enough to cover these variations while using basic commonprinciples. This is the fundamental goal of the IPEX Pre-assembled Control Panel concept.

7-1.2 Panel Design Process

IPEX analyzed the similarities and the likely variations in design based on a series of specific heating applica-tions. The goal was to offer a number of pre-designed and pre-assembled control panels that installers canchoose from to match the project at hand. By looking at the details of the heating application, the appropriatesupply and return manifolds and controls can be selected and assembled in a professional enclosure.

The potential result would be time and money saving off-the-shelf solutions that put a professional finishing touchto almost any radiant heating application. In order to establish the final panel offering though, a number of designquestions had to be addressed.

Will the hydronic system operate as a closed loop system or an open loop system? What pressures will the pipingsystem operate under? Answering these two questions narrows the selection of components considerably. Howwill the heat input be controlled? Do we need to control every pipe loop independently? Would zone control bemore appropriate? Again, answering these questions further defines the specific components necessary for theproject.

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The IPEX WarmRite Control Panel product line wasdeveloped using this process, in combination withvaluable feedback from the North American marketplace. The result is the following eleven differentControl Panels (CP)

Injection Mixing CP

Recirculating Zone CP

Recirculating Zone CP with Expansion Tank

CP with Heat Exchanger

Floor Warming CP

Multi Zone Manifold Station

Manifold Station with Circulator

Manifold Station

Snowmelt / Industrial CP

Injection Mixing Secondary CP

Isolation Module

Each control panel is described in this section.However, because the panels have numerous commonelements, a review of their similarities is in order. Fordetailed information, application notes and installation/ operation manuals are available for each panel.

7-1.3 Operating Principles

All panels are designed to control the average floortemperature required to compensate for ongoing heatloss. Each panel does this by cycling between heatinput (on cycle) and no heat input (off cycle). Duringthe on cycle, additional heat is added to the pipe loopsto bring the floor temperature to its desired level. Theratio between the on and off cycle is proportional to theaverage heat needed in the floor. Simply put, if it iswarm outside the heat loss is low. The on cycle is shortand the off cycle is long. If the opposite is true and itis cold outside, the heat loss will be high causing theon cycle to be long and the off cycle to be short. Inprinciple, radiant floor systems are designed so that onthe coldest day of the year, the on cycle will operate100% of the time.

7-1.4 Supply Water Temperature

Most panels operate on constant supply temperature.Only the Injection Mixing Control Panel modulates-changes continuously-the supply temperature based onoutdoor reset. The Control Panel with Heat Exchangerand the Floor Warming Control Panel have a built-in

tempering valve to set the supply temperature. Thesethree panels control the floor supply temperature so noexternal supply water temperature control is needed.All other panels rely on receiving the calculated designwater temperature.

7-1.5 Space Temperature Control

Most of the panels are primarily operated as a zonecontrol mechanism. They can provide loop control ifnecessary, but one should always consider the way thebuilding is used and clarify if zone control is appro-priate, or if loop by loop control is needed. Loop byloop control always requires more hardware compo-nents than zone control.

Designers should consider how the building is used.Who is using it? What comfort level is required? Howeven and constant is the required indoor temperature?What level of accuracy is required from the controlsystem? One must first identify what is really requiredand design accordingly.

7-1.6 Why zone control?

It is fair to say that the most fundamental requirementof every heating system is to provide constant temper-ature in the heated space. There are exceptions ofcourse, but mostly a set temperature is desiredthroughout the heating season. The opposite of thisoccurs if a building needs to be heated only for a shorttime, then cooled and heated again. In most cases,high mass radiant floor may not be the best option forthis type of heating pattern. Where radiant heatingthrives is in constant temperature environments. Thisbeing the case, the fundamental requirement is to beable to set a desired temperature and allow the systemto maintain it - this is what zone control does best. Toclarify, zone control means that all pipe loops (or heatemitters) connected to a manifold are controlled by onethermostat or sensor. However, this does not mean thatthe temperature must be the same in all areas coveredby the loops from a single manifold. Different temper-atures can be set within the zone by adjusting thebalancing valve on each loop. Adjusting the flow rateloop results in different temperatures in the areascovered by the loops.

7-1.7 Setting the Temperature

All panels have a balancing valve for each pipe loopfitted on the return manifold. Most panels also haveflow rate indicators on the return manifold. The desiredtemperature relationship can be set easily and with noadditional hardware-i.e. a thermostat in every room andan actuator on every loop. This approach to temper-ature control works very well as long as the preference

75

is for a consistent temperature pattern which is notoften altered. The temperature difference between theareas will remain the same unless the balancing valvesare readjusted.

Naturally there are applications when the temperaturesetting has to be changed more frequently - such as amotel where guests change every day, and with them sodo individual comfort requirements. Perhaps in ourown home there is a guest bedroom that is only usedsporadically. In these cases, separate thermostats arerequired. The pipe loops serving these spaces will havevalve actuators connected to the appropriate roomthermostat. When the room is occupied and thatthermostat calls for heat, valves open on those loopsuntil the appropriate setting is satisfied. The provisionfor individual loop valves is available on all WarmRiteFloor control panels designed for residential or officeenvironments.

Industrial and Secondary Injection Mixing ControlPanels differ from the others in that the environmentsthey are designed for rarely require loop by loopcontrol. In large areas, the flow adjustment in a singleloop has virtually no effect on the overall heat output.There are no sophisticated balancing or actuated valvesin these panels because they are not required. All ofthe other control panels have been designed to accom-modate individual loop by loop control when required.

Every panel designed for closed loop systems has anautomatic air vent on the supply manifold and afill/drain valve on both manifolds. Each is equippedwith a pressure gauge on the return manifold and two

temperature gauges: one for supply and one for returnwater temperature. The temperature drop in the systemcharacterizes best how the unit is operating.

7-1.8 Protection from Overheating

All panels - except the manifold station - are fitted witha limit thermostat to protect the floor from over-heating. Floor surface temperature should be less than85 deg. F. for human comfort. The limit thermostatmonitors the supply water temperature which is propor-tional to the floor surface temperature. If the supplytemperature reaches the setpoint, the limit thermostatturns off the heat input. This is a factory setting basedon typical concrete slab installations. When highersupply temperatures are required, it can be readjustedaccordingly. See the Application Notes and Installation/ Operation Manual supplied with each panel for moredetails.

SECTION 7 PRE-ASSEMBLED CONTROL PANELS


76

7-2 CONTROL PANELS

Injection Mixing Control Panel

Operation:

This panel is designed to control supply fluidtemperature by injection mixing. The WarmRiteControl provides variable speed operation of aninjection circulator based on outdoor air temper-ature. This panel is ideal when supply temperaturecontrol is required. The application of this panel isextended to control the return water temperaturefor conventional boilers by installing the returnwater temperature sensor.

When the control is in the outdoor reset mode, thespeed of the injection circulator is varied tomaintain a target fluid temperature in the supplymanifold based on outdoor air temperature. Thecontrol can alternately be used as a set pointcontrol. In this mode, the speed of the injectioncirculator is varied to maintain a user adjustablesupply fluid temperature. A room thermostatmonitors the desired room temperature and turns the mixing control off when the zone(s) is satisfied.

The panel is operated as a single zone system by using the thermostat to activate the control. The secondarycirculator operates continuously providing even heat distribution during the heat up and cool down cycles. Thepanel can be operated with subzones set up on a single zone panel. The system thermostat is operating the mainheat input while the subzone thermostats operate the loops fitted with valve actuators. The sub zoning shouldnot exceed more than 50% of the loops. The panel can be operated as a multiple zone system. The on/off valveslocated on the supply manifold are fitted with optional electrical valve actuators to control individual loops in thesystem. In this application, every actuator is connected to a thermostat located in the area served by the loop.When the thermostat calls for heat, the actuator opens the loop allowing flow. When all loops are satisfied, thesecondary circulator is shut down and the injection control is disabled.

The panel operation is controlled by closure of a dry contact. An example of devices that can provide this are:two and three wire room thermostats, programmable thermostats, set point controls, integrated building controls,etc. Balancing valves with flow indicators on the return manifold allow the user to adjust and visually monitor theflow rates of each loop. A circulatorcontrol module contains a 24V trans-former, a circulator relay, a dry contactenable, and an adjustable high limitwhich prevents the supply fluid fromexceeding the desired temperature. Valveson the supply and return manifolds alloweach loop to be isolated when necessary.The optional actuators and thermostatsmust be ordered separately according tothe project specifications.

The panel operation is controlled byclosure of a dry contact. An example ofdevices that can provide this are: two andthree wire room thermostats,programmable thermostats, set pointcontrols, integrated building controls, etc.

pressure / temperaturegauges

secondary circulatorinjection circulator

isolating valves

WarmRitecontrol

return manifold

supply manifold

automatic airvent

fill/drainvalve

INJECTION MIXING CP

limit sensor

circulatorcontrolmodule

actuatormodule (3z)

RETURNSUPPLY

77

Recirculating Zone Control Panel

Operation:

This panel is designed as a manifold station that provides constant circulation in the distribution system. Thereis no supply water temperature control in the panel.

The panel operates primarily as a single zone system maintaining the average space temperature. A thermostatand a diverting valve control the heat input. It cycles the heat-input on/off to match the average heat loadrequirement in the zone. Fluid circulatesfrom the heat source to the panel andthrough the floor piping. When the zone issatisfied, the diverting valve closes thepath to the heat source and removes theexternal enable signal. The fluid continu-ously circulates in the floor piping,providing even heat distribution both onheat up and cool down cycles.

Balancing valves with flow indicators onthe return manifold allow the user toadjust and visually monitor the flow ratesof each loop. A circulator control modulecontains a 24V transformer, a circulatorrelay, a dry contact enable, and anadjustable high limit which prevents thesupply fluid from exceeding the desiredtemperature. Valves on the supply andreturn manifolds allow each loop to beisolated when necessary.

The panel operation is controlled by closure of a 24V dry contact. An example of devices that can provide thisare: two and three wire room thermostats, programmable thermostats, set point controls, indoor/outdoor resetcontrols, integrated building controls, etc.



circulator

divertingvalve

isolating valves

return manifold

supply manifold

fill/drain valve

RECIRCULATING ZONE CP

limit sensor


actuatormodule(3z)

purge valve

RETURNSUPPLY


78

Recirculating Zone Control Panel with Expansion Tank

Operation:

This panel is designed as a manifold station that provides constant circulation in the distribution system. Thereis no supply water temperature control in the panel.

The panel operates primarily as a single zone system maintaining the average space temperature. A thermostatand a diverting valve control the heat input. It cycles the heat-input on/off to match the average heat loadrequirement in the zone. Fluid circulates from the heat source to the panel and through the floor piping. Whenthe zone is satisfied, the diverting valve closes the path to the heat source and removes the external enable signal.The fluid continuously circulates in the floor piping, providing even heat distribution both on heat up and cooldown cycles.

Balancing valves with flow indicators onthe return manifold allow the user toadjust and visually monitor the flow ratesof each loop. A circulator control modulecontains a 24V transformer, a circulatorrelay, a dry contact enable, and anadjustable high limit which prevents thesupply fluid from exceeding the desiredtemperature. Valves on the supply andreturn manifolds allow each loop to beisolated when necessary.

The panel operation is controlled byclosure of a 24V dry contact. An exampleof devices that can provide this are: twoand three wire room thermostats,programmable thermostats, set pointcontrols, indoor/outdoor reset controls,integrated building controls, etc.

SUPPLY

Installed By / Installe Par

RETURN

pressure /temperature

gauges

circulatordivertingvalve

isolating valves

return manifold

supply manifold

fill/drain valve

RECIRCULATING ZONE CP with EXP. TANK

limit sensor


actuatormodule

(3z)expansion tank

shut off valve

79


Control Panel with Heat Exchanger

Operation:

This panel is designed to separate the secondary system fluid from the primary system fluid by utilizing a plateheat exchanger, and is recommended for applications that use an open loop system as the heat source or in appli-cations where a water/glycol mixture is used in the secondary heating loop.

The secondary system is filled during installation and operates as a closed loop circuit. The panel comes with anexpansion tank and relief valve for the secondary side of the system. The design supply fluid temperature in theprimary loop is set with a tempering valve.

The panel is operated as a single zonesystem by using a thermostat to activatethe primary circulator. The secondarycirculator operates continuously providingeven heat distribution during the heat upand cool down cycles.

The panel can also be operated as amultiple zone system. The on/off valveslocated on the supply manifold can befitted with optional electrical valveactuators to control individual loops in thesystem. In this application, every actuatoris connected to a thermostat located inthe area served by the loop. When thethermostat calls for heat, the actuatoropens the loop allowing flow. When allloops are satisfied, the primary andsecondary circulators are shut down.

Balancing valves with flow indicators on the return manifold allow the user to adjust and visually monitor the flowrate of each loop. The circulator control module contains a 24V transformer, a circulator relay, a dry contactenable, and an adjustable high limit which prevents the supply fluid from exceeding the desired temperature.Valves on the supply and return manifolds allow each loop to be isolated when necessary. The optional actuatorsand thermostats must be ordered separately according to project specifications.


RETURNSUPPLY

pressure / temperature gauges

secondarycirculator

primarycirculator

manual airventheat exchanger

isolating valves

shut off valve

expansion tank

return manifold

supply manifold

automatic airvent

pressurereliefvalve

purge valve

CP with HEAT EXCHANGER

actuatorcontrol(x3)


limit sensor

shut off valve temperingvalve


80

Floor Warming Control Panel

Operation:

This panel is designed to operate floor warmingand basic heating systems. This panel incorpo-rates non-ferrous components to allow use withthe domestic water supply where permitted.

The panel is supplied with a programmablethermostat to sense slab temperature or airtemperature depending on the application. In afloor warming application the thermostat isprogrammed to sense slab temperature. In aspace heating application it is programmed tosense air temperature, or optionally air and slabtemperature.

The thermostat can be programmed to circulatethe water throughout the year to preventstagnation when utilizing a domestic water heatsource. A built in tempering valve allows controlof supply water temperature.

The panel is operated as a single zone system by using the thermostat to activate the circulator. The panel canbe operated as a multiple zone system. The on/off valves located on the supply manifold can be fitted withoptional electrical valve actuators to control individual loops in the system. In this application every actuator isconnected to a thermostat located in the area served by the loop. If periodic circulation to avoid stagnation isrequired, all thermostats on the system must be programmable thermostats with timer capabilities.

Balancing valves with flow indicators on the return manifold allow the user to adjust and visually monitor the flowrate of each loop. The circulator control module contains a 24V transformer, a circulator relay, a dry contactenable, and an adjustable high limit that prevents the supply water from exceeding the desired temperature.Valves on both the supply and return manifolds allow for isolation of the loop when necessary.

The panel operation is controlled by closure of a 24V dry contact. The panel comes complete with aprogrammable thermostat, but also may be controlled by devices such as: two and three wire room thermostats,set point controls, indoor/outdoor reset controls, integrated building controls, etc.

RETURN SUPPLY

circulator

temperingvalve

isolating valves

return manifold

supply manifold

FLOOR WARMING CP

limit sensor


actuatormodule (3z)


programmable thermostat with slab sensor

purgevalve

81


Multi Zone Manifold Station

Operation:

This panel is used as multiple zone system. The on/off valves located on the supply manifold are fitted withelectrical valve actuators to control individual loops in the system. Every actuator must be connected to athermostat located in the area served by the loop(s). When the thermostat calls for heat, the actuator opens theloop allowing flow. The pressure balancing bypass valve equalizes the changing head loss conditions as variousloops open and close. When all loops are satisfied the dry contact in the circulator control module opens.

Balancing valves with flow indicators onthe return manifold allow the user toadjust and visually monitor the flowrates of each loop. A circulator controlmodule contains a 24V transformer, acirculator relay, a dry contact enable,and an adjustable high limit whichprevents the supply fluid from exceedingthe desired temperature. Valves on thesupply and return manifolds allow eachloop to be isolated when necessary. Thethermostats must be ordered separatelyaccording to the project specifications.

Each actuator's operation is controlledby closure of a 24V dry contact. Anexample of devices that can provide thisare: two and three wire roomthermostats, programmable thermostats,set point controls, integrated buildingcontrols, etc.

isolating valves

return manifold

supply manifold

automaticairvent

pressurebalancingbypass

MULTI ZONE MANIFOLD STATION


actuators

limit sensor


actuatormodule (x3)

actuatormodule (x3)

actuatormodule (x3)

actuatormodule (x3)

fill/drain valve

fill/drain valve

RETURN

SUPPLY


82

Manifold Station with Circulator

Operation:

This panel is designed as a basic manifold station.

The panel is operated as a single zone system by using a thermostat to activate the circulator.

The panel can also be used as multiple zonesystem. The on/off valves located on the supplymanifold can be fitted with optional electricalvalve actuators to control individual loops in thesystem. In this application, every actuator isconnected to a thermostat located in the areaserved by the loop. When the thermostat calls forheat, the actuator opens the loop allowing flow.When all loops are satisfied the circulator is shutdown.

Balancing valves with flow indicators on thereturn manifold allow the user to adjust andvisually monitor the flow rates of each loop. Acirculator control module contains a 24V trans-former, a circulator relay, a dry contact enable,and an adjustable high limit which prevents thesupply fluid from exceeding the desired temper-ature. Valves on the supply and return manifoldsallow each loop to be isolated when necessary.The optional actuators and thermostats must beordered separately according to the project specifications.


circulator

isolatingvalves

return manifold

supply manifold

automatic airvent

MANIFOLD STATION with CIRCULATOR

pressure / temperaturegauge

limit sensor


actuatormodule (x3)

fill/drain valve

fill/drainvalve

RETURN SUPPLY

83


Manifold Station

Operation:

This panel is designed as a basic manifold station.

The panel is operated as a single zone system by using a thermostat to activate the external zone valve or a circu-lator.

The panel can also be used with limited numberof subzones. The on/off valves located on thesupply manifold can be fitted with optionalelectrical valve actuators to control individualloops in the system. In this application, everyactuator is connected to a thermostat located inthe area served by the loop. When the thermostatcalls for heat, the actuator opens the loopallowing flow.

Balancing valves with flow indicators on thereturn manifold allow the user to adjust andvisually monitor the flow rates of each loop. Theunit has no integral zone control device. When azone valve or circulator is attached to themanifold station a Circulator Control Module hasto be fitted in the system. This controls the zonevalve or circulator and the loop valve actuatorsfor the subzones. The circulator control modulecontains a 24V transformer, a circulator relay, a dry contact enable, and an adjustable high limit which preventsthe supply fluid from exceeding the desired temperature. Valves on the supply and return manifolds allow eachloop to be isolated when necessary. The optional actuators and thermostats must be ordered separately accordingto the project specifications.

isolatingvalves

return manifold

supply manifold

automatic airvent

MANIFOLD STATION


fill/drainvalve

fill/drain valve

limit sensor

RETURN

SUPPLY


84

Snowmelt / Industrial Control Panel

Operation:

This panel is designed to operate snowmelt or industrial heating systems, which are usually designed with pipeloops of equal length.

In these circumstances individual loop flow rate adjustment is not required, nor is recirculation necessary. Anexternal control turns the circulator on when heat is required.

Valves on the supply and return manifolds are used if flow rate compensation is required. They may also be usedto isolate each loop for instal-lation and servicing ease. Acirculator control modulecontains a 24V transformer, acirculator relay, a dry contactenable, and an adjustable highlimit which prevents the supplyfluid from exceeding the desiredtemperature.

The panel operation is controlledby closure of a 24V dry contact.An example of devices that canprovide this are: two and threewire room thermostats,programmable thermostats, setpoint controls, indoor/outdoorreset controls, snow meltcontrols, integrated buildingcontrols, etc.

SUPPLY

RETURN

circulator

isolatingvalves

return manifold

supply manifold

automaticairvent

SNOWMELT / INDUSTRIAL CP


limit sensor


actuatormodule (3z)

fill/drain valve

pressurerelief valve

SECTION 12 DESIGNING MULTIPLE-LOAD HYDRONIC SYSTEMS

85

Injection Mixing Secondary Control Panel

Operation:

This panel is designed to function as a remote secondary circuit of an injection mixing system to heat largecommercial/industrial spaces. This design concept takes advantage of the high temperature drop across theinjection bridge which allows for low flow rates. The reduced flow rates in turn allow the use of smaller pipe sizesfrom the boiler room to the remotely mounted panel. Large commercial/industrial spaces often require multipleremotely mounted manifolds. Thispanel allows a single WarmRite Controland injection circulator to provide therequired temperature fluid to all panels,eliminating the need for multiplecontrols.

The secondary circuit in the panelconstantly circulates the fluid in thefloor loops. The room thermostatprovides a call for heat to the centrallylocated WarmRite control.

Balancing valves on the supply andreturn manifolds are used if flow ratecompensation is required. They mayalso be used to isolate a loop whennecessary. A circulator control modulecontains a 24V transformer, a circulatorrelay, a dry contact enable, and anadjustable high limit which prevents thesupply fluid from exceeding the desiredtemperature.


circulator

isolating valves

return manifold

supply manifold

automatic airvent

fill/drainvalve

INJECTION MIXING SECONDARY CP


actuatormodule

(x3)

limit sensor

secondarymixing tees

RETURN

SUPPLY


86

Isolation Module

Operation:

This module is designed to isolate the liquid used in the heating loop from the liquid used in the heat source.For example, a snowmelt system operating with water-glycol mixture is connected to a heat source operating withwater or separating a heating system from a domestic water heat source.

The primary side of the heat exchanger is connected to the heat source. The primary circulator and the isolatingvalves are included in the panel. The secondary side contains an expansion tank, pressure relief valve, andisolating valves. Each circuit ismonitored with a pressure /temperature gauge.

A circulator control modulecontains a 24V transformer, acirculator relay, a dry contactenable, and an adjustable highlimit that prevents the supply fluidfrom exceeding the desired temper-ature.

The panel operation is controlledby closure of a 24V dry contact. Anexample of devices that canprovide this are: two and three wireroom thermostats, programmablethermostats, set point controls,indoor/outdoor reset controls,integrated building controls, etc. primary

return supplysupply returnsecondary

limit sensor


primarycirculator

heatexchanger

exp.tank

pressurerelief valve


SUPPLY

S RETURN

P RETURNP SUPPLY

SECTION

8

DISTRIBUTION SYSTEMS FOR

HYDRONIC HEATING

There are several methods of transporting water from a hydronic heat source to one or more heat emitters. Themethod used depends on:

• How much water has to be moved?

• Can the heat emitters operate properly at different water temperatures?

• Do some portions of the piping system need to operate as different zones?

• Are there several circulators that must operate simultaneously?

• What type of pipe will be used to convey heated water to the heat emitters?

This section examines several “classic” hydronic distribution system configurations. It also discusses severalunique ways to use PEX-AL-PEX pipe to create distribution systems that are easy and fast to install, as well asefficient to operate.

8-1 Series Loop Systems

The simplest way of connecting two or more hydronic heat emitters is in a series loop. Heated water flows intothe first heat emitter, gives up some heat, exits that heat emitter and enters the next one in the loop. An exampleof a series piping loop using composite piping to connect several fin-tube baseboards together is shown in Figure8-1.

Series piping circuits, although simple to build do have a number of limitations. Chief among these limitationsis the lack of individual heat output control for each heat emitter. Series loops should be limited to a buildingarea that can be controlled as a single zone. Avoid series circuits if one or more of the heat emitters is locatedin a room with high internal heat gains compared to other rooms.

87


88

If the water temperature supplied to a series loop ischanged to increase or decrease the heat output of oneheat emitter, the output of all other heat emitters onthe loop will be effected. This also holds true if oneattempts to adjust heat output by changing the flowrate through the loop.

Another potential limitation of series loop is excessivehead loss (e.g. pressure drop). In a series loop the headlosses (pressure drops) of each heat emitter and inter-connecting piping add together. Too many heatemitters in series could lead to high pressure drops andlow flow rates. This often shows up as under heatedrooms near the end of the loop.

Series loops containing several heat emitters should bedesigned to accommodate the drop in water temper-ature from one heat emitter to the next. If the flow ratein the circuit is known, the temperature drop acrosseach heat emitter can be determined using formula 8-1:

Where:

∆T = Temperature drop across the heat emitter (deg. F)

Q = Rate of heat output by the heat emitter (Btu/hr)

f = Flow rate in the circuit (in gpm)

500 a constant for water (use 479 for 30% and 450 for 50% glycol)

For example: Assume water enters a length of fin-tubebaseboard at 170 deg. F. and 2 gpm. The baseboardreleases heat at a rate of 10,000 Btu/hr. What is theoutlet temperature from the baseboard?

Solution:

Therefor the water exits at 170-10 = 160 deg. F.

Formula 8-1 can be used sequentially to determine the∆T = Q

500 x f

∆T=Q

500 x f= 10,000

500 x 2= 10ºF

Figure 8-1

Formula 8-1

89

temperature drop from one heat emitter to the next.Remember that as the water temperature drops in thedownstream direction the size (or length) of the heatemitter needed for a given heat output increases.

8-2 Home Run Distribution Systems

The ability of PEX-AL-PEX extends far beyond radiantpanel heating systems. Its ability to handle relativelyhigh water temperatures combined with ease of instal-lation makes it ideal for piping traditional hydronicheat emitters such as fin-tube baseboard, cast-ironradiators and baseboard, and panel radiators.

The concept for a “home run” piping system is shownin figure 8-2. It employs the same piping and manifoldcomponents used for radiant panel systems.

The difference is that the tubing circuits are not part ofthe heat emitter. Instead, they carry heated water toand from individual heat emitters.

In a home run system each heat emitter has its ownsupply and return tube. This allows each heat emitterto be supplied with approximately the same watertemperature. The drop in water temperature associatedwith a series loop system is no longer an issue. Eachheat emitter connected to the manifold can be sized atthe same water temperature. Since the heat emittersdon’t have to be “up sized” to compensate for reducedwater temperature the overall cost of the heat emitters

selected may be reduced.

Homerun systems also allow each circuit to becontrolled as an independent zone. When each room isserved by its own homerun circuit the temperature ofeach room can be adjusted as desired. Unoccupiedrooms can be set at low temperatures to conserve fuel.Heat output to a room that experience solar heat gainscan be interrupted when necessary without compro-mising comfort in other rooms. The temperature inbedrooms can be reduced during sleeping hours ifdesired, while bathrooms can remain warm for showersand baths.

One way of providing room-by-room zone control is byadding low voltage electric valve actuators to the valveson the manifold. These actuators are controlled by thethermostats in each room. When the room thermostatcalls for heat it sends a 24 volt AC signal to theassociated actuator. The actuator then opens themanifold valve to which it is attached. An isolated endswitch with the valve actuator provides a contact thatis used to turn on the circulator and heat source.

Non-electric thermostatic radiator valves (TRVs) canalso be used in conjunction with a homerun distri-bution system to provide individual temperature controlin each room. TRVs adjust the flow rate of heated waterthrough the heat emitters to regulate heat output. Theydo not have the ability to signal for circulator or boileroperation. In this type of distribution system the circu-

SECTION 8 DISTRIBUTION SYSTEMS FOR HYDRONIC HEATING

Figure 8-2


90

lator runs continuously throughout the heating season.The water temperature supplied to the heat emitters isoften regulated by an outdoor reset control. The colderit is outside the warmer the water temperature.

Still another benefit of homerun distribution systems isthe reduced pressure drops they create in comparisonto a series piping loop. Lower pressure drops oftenallow a smaller, less power consuming circulator to beused. This saves not only on installation cost, but alsoon operating cost over the long life of the system.

When designing a homerun distribution system keep inmind that some hydronic heat emitters such as panelradiators and lengths of fin-tube baseboard can besized to operate with temperature drops as high as 40deg. F. under design load conditions. Such hightemperature drops allow significant reductions in theflow rate supplied to the heat emitters. This in turn canallows the use of small tubing such as 3/8” Kitec PEX-AL-PEX for the homerun circuits.

For example, a panel radiator delivering 10,000 Btu/hrwith 180 deg. F inlet, and 140 deg. F. outlet watertemperature only needs about 0.5 gpm of flow. Thiscould easily be handled by 3/8” tubing.

Such small diameter tubing is easily routed throughframing cavities, even cavities that are closed off. Ingeneral, if a piece of electrical cable can be pulledthrough the building from one location to another, socan a length of small diameter composite tubing. This

makes the homerun approach ideal for retrofit jobswhere framing cavities may have limited access.

When individual circuit control is used, a differentialbypass valve should be installed across the manifold asshown in figure 8-2. It provides a flow bypass thatprevents the circulator from “dead heading” when allthe manifold valves are closed. Adjust the knob on thedifferential pressure bypass valve so it just beginsbypassing flow when all the zone circuits are on, thenincrease the pressure setting slightly. As the individualhomerun circuits close off the bypass valve will take anincreasing percentage of the manifold flow and preventthe circulator from imposing a high pressure differ-ential on the circuits that remain active.

8-3 Parallel (“2-pipe”) Distribution Systems

Another hydronic distribution system that suppliesapproximately the same water temperature to eachheat emitter is called a parallel (or “2-pipe”) system.In this type of system, each heat emitter is piped intoa crossover bridge that crosses from a supply main to areturn main.

Direct Return Piping:

One form of a parallel (2-pipe) distribution system isspecifically called a direct return system. An exampleof the piping arrangement is shown in figure 8-3.

Figure 8-3

91

Notice that the crossover bridge closest to the supplyside of the heat source and circulator is also the closestto the return end of the system. The farther out theother crossover bridges are the longer the flow path ofthe circulating water. To obtain the proper flow ratethrough each heat emitter a flow balancing valve mustbe installed in each crossover bridge. The amount eachbalancing valve is closed depends on the intended flowrate through each heat emitter as well as its position onthe mains. Although it is possible to calculate thenecessary Cv setting of each balancing valve this isseldom done. Instead, the valves are set through a trialand error process until the heat outputs of all heatemitters are acceptable.

Parallel direct-return distribution systems can beconstructed of Kitec PEX-AL-PEX pipe. Largerdiameter composite piping can be used to create themains, while small pipe sizes can be used to create therungs. Notice how the pipe size of the mains decreasesas the distribution system expands away from themechanical room.

Reverse Return Piping:

Another variation on the parallel piping concept is

called a reverse return system. An example is shown infigure 8-4.

In a reverse return system the first crossover bridgeattached to the supply main is, in effect, the last to beattached to the return main. This arrangement helpsequalize the piping path length through each heatemitter. This in turn help naturally balance flowthrough the system, especially with the attached heatemitters have similar flow resistance. Because of itsability to be self balancing reverse return systems areoften preferred over direct return systems.

The optimal arrangement of a parallel reverse returncircuit within a building is shown in figure 8-5. Noticethat the distribution system makes a loop around thebuilding rather than a “dead end” at the farthest pointout.

8-4 Primary/Secondary Distribution Systems

The concept of primary / secondary (P/S) piping datesback to the 1950s when it was applied mostly forlarger commercial systems, especially chilled watercooling applications. However, renewed interest inradiant floor heating, combined with increasinglysophisticated residential and light commercial applica-


Figure 8-4


92

tions prompted designers to look for a piping methodmore flexible and forgiving than the standard 2-pipesystem. They soon rediscovered the elegant simplicityof primary / secondary piping, and were able tosuccessfully integrated with modern controls. Todaymethod of piping is rapidly becoming the standardsetter as the backbone upon which to build modernmulti-load / multi-temperature hydronic systems.

The fundamental concept of a P/S system is touncouple the pressure differential established by anygiven circulator, from that established by other circu-lators in the same system. P/S piping allows eachcirculator in the system to operate with virtually notendency to induce flow, or even disturb flow, incircuits other than it’s own. In effect each circulator“thinks” it’s circuit is the only circuit in the system.This allows a number of circulators with different headand flow rate characteristics to operate simultaneouslywithout interfering with each other.

The Primary Loop:

All primary /secondary systems have a primary loopthat serves as the hot water “bus bar” for one or moresecondary circuits. An example of a simple primary

circuit is shown in figure 8-6.

The function of the primary circuit is to deliver hotwater to each of the secondary circuit attached to it.

Figure 8-6

Figure 8-5

93


The primary circulator produces flow in the primaryloop only, and is NOT intended to create or even assistwith flow in any of the secondary circuits.

Each secondary circuit is attached to the primarycircuit using a pair of closely spaced tees as shown infigure 8-7.

Since the pressure drop between the closely spacedtees is almost zero, there’s virtually no tendency forflow in the primary circuit to create flow in thesecondary circuit.

When a secondary circulator is turned on, it establishesits own pressure differential in its secondary circuit.This in turn draws flow from the upstream tee in theprimary loop, sends the flow through the secondarycircuit, and returns it to the downstream tee in theprimary loop. The primary loop functions as the sourceof hot water as well as a return path, instead of directpiping connections to the heat source itself.

The primary loop also becomes the pressure referencepoint for the secondary circuits. It acts as the point ofconnection to an expansion tank for each of thesecondary circuits. Because of this, it’s important thateach secondary circulator pumps into its associatedsecondary circuit, (e.g. away from the expansion tankreference point). This allows the pressure in thesecondary circuit to increase when the secondary circu-

lator operates.

Series Primary Loops:

A series primary loop is created when two or moresecondary circuits are arranged in sequence along theprimary loop as shown in figure 8-8.

When designing a series primary loop it’s necessary toaccount for the temperature drop associated with eachoperating secondary circuit. Formula 8-1, repeatedbelow, can be used for this purpose.

Where:

∆T = Temperature drop in the primary loop acrossthe tees of an operating secondary circuit (deg.F)

Q = Rate of heat delivery to the secondary circuit(Btu/hr)

f = Flow rate in the primary circuit (in gpm)

500 a constant for water (use 479 for 30% and 450 for 50% glycol)

∆T = Q500 x f

Formula 8-1

Figure 8-7


94

The heat emitters in the various secondary circuitsneed to be sized for the water temperature available tothem based on where they connect to the primarycircuit. The farther downstream a given secondarycircuit connects to the primary loop, the lower thewater temperature it has available (assuming theupstream secondary circuits are operating).

It’s usually best to place secondary circuits with highertemperature requirements near the beginning of theprimary circuit, and those that can work with lowerwater temperatures near the end.

If a conventional boiler is used as the heat sourcealways check that the water temperature at the end ofthe primary loop (when all loads are operating) is abovethe dew point of the boiler’s exhaust gases. Minimumreturn temperatures of 130 deg. F. for gas-fired boilers,and 150 deg. F. for oil-fired boilers are oftensuggested.

Preventing Heat Migration:

It’s very important to protect secondary circuits fromoff-cycle heat migration (e.g. the undesirable flow of

hot water into a secondary circuit when its circulator isoff). This migration is causes by two factors.

First there’s the natural tendency of hot water to“thermosiphon” through an unblocked piping looplocated above the heat source. Hot water is lighter thancool water. Given an unblocked piping path that risesabove the heat source this difference in buoyancy willmaintain a weak, but persistent flow. Under suchconditions the piping loop and any heat emitter itcontains serves as a heat dissipater that could easilyoverheat spaces that simply don’t need any heat inputat the time.

Another factor that causes heat migration is the factthat the pressure drop between the closely-spaced teeswhere the secondary circuit connects to the primaryloop is not quite zero. The slightly higher pressure atthe upstream tee will try to push some hot water intothe secondary circuit.

Every secondary circuit in a P/S system must includedetailing to prevent heat migration when its circulatoris off. One method is to install a flow-check valve(which has a weighted plug) on both supply and return

Figure 8-8

95

risers of the secondary circuit. The opening pressure ofthese valves is about 1/4 psi. This is sufficient toprevent buoyancy forces from setting up athermosiphon flow pattern when the secondary circu-lator is off. A spring-loaded check valve is anacceptable alternative to a flow-check in theselocations. These details are shown in figure 8-9.

Two other options exist for the return riser of asecondary circuit. One is the under slung thermal trapshown in figure 8-9. Another is a swing check. Neitherof these can stop forward flow caused by buoyancyforces and therefore should only be used on the returnside of a secondary circuit.

Purging:

The closely spaced tees connecting a secondary circuitto the primary circuit make it difficult to purge the

secondary circuits by forcing water around the primaryloop. The solution is to install separate purging valveson the return side of each secondary circuit as shownin figure 8-9. During purging the ball valve is closedforcing pressurized make-up water in the desireddirection through the secondary circuit as air is blownout through the open hose bib.

Sizing the Primary Circulator:

Every circulator in a P/S system functions as if it wereinstalled in an isolated circuit. The primary circulatordoes not assist in moving flow through any of thesecondary circuits, or vice versa. The function of theprimary loop is simply to convey hot water from theheat source around the primary loop. In the process thewater temperature drops by some intended design ∆T.

The flow rate necessary to deliver the output of the


Figure 8-9


96

heat source using a selected temperature drop can befound using formula 8-2:

Where:

fprimary = Flow rate in the primary circuit (gpm)

Q = Heat output rate of the heat source (Btu /hr)

∆T = Intended temperature drop of the primary circuit (deg. F.)

500 = A constant for water at an average temperature of 140ºF., (use 479 for 30% glycol, 450 for 50% glycol)

For example: Assume a primary circuit is connected toa boiler having an output rating of 100,000 Btu/hr. Theintended temperature drop of the primary loop with allsecondary loads operating is 20 deg. F. What is thenecessary primary loop flow rate?

Solution:

The designer now chooses a piping size and estimatesthe head loss of the primary loop based on this flowrate. A circulator capable of providing the necessaryhead at the calculated flow rate is then selected.Notice there was no need to examine the specifics ofthe secondary circuits when selecting the primary loopcirculator.

Selecting a high temperature drop (∆T) for the primarycircuit results in lower flow rates, and often reducesprimary loop pipe size. It may also reduce the size ofthe primary loop circulator. However, selecting a largetemperature drop also implies lower supply watertemperature to secondary circuits located fartherdownstream along the primary loop. This is fine forsystems using both high temperature and lowertemperature heat emitters provided the higher temper-ature secondary circuits are located near the beginningof the primary loop, while those with lower watertemperature requirements are located near the end.

Split Primary Circuits:

When the same water temperature needs to besupplied to each of several secondary circuits, theprimary circuit can be split into several parallelcrossover bridges as shown in figure 8-10.

Each crossover bridge should have a flow-balancingvalve so flow rates can be proportioned to the loadsbeing supplied. See figure 8-11. For example, if onecrossover bridge serves a load that has twice theheating requirement of a load on another crossoverbridge, that bridge should have about twice the flowrate of the other. The pipe sizes of the crossoverbridges can even be different if necessary dependingon the flows needed. The split primary loop approachis especially helpful when several of the secondarycircuits need to operate within a narrow water temper-ature range.

Secondary Circuit Design:

The design of secondary circuits is not limited to aseries loop of heat emitters. Any piping design thatcould be connected to a boiler can also be connectedto the closely spaced tees at the P/S interface. Someexamples are shown in figure 8-12.

The secondary circuit risers can even be treated as“headers” from which two or more independentlycontrolled zone circuits can begin and end. Anotheroption is to configure the secondary circuit as a twopipe direct- or reverse-return subcircuit. The secondarycircuit can also be set up as a home run subsystem useseveral independent circuits of Kitec pipe to supplyindividual heat emitters.

Secondary circuits can also contain a mixing deviceallowing them to operate at lower water temperaturesthan the primary loop.

Examples are shown in figure 8-13.

fprimary = Q500 x ∆∆T

Formula 8-2

= 100,000500 x 20

= 10gpmfprimary = Q500 x ∆∆T

Figure 8-10

97


Figure 8-12

Figure 8-11


98

When a mixing device is used to reduce the supplytemperature in the secondary circuit the primary loopcreates a second mix point that boosts water temperature returning to the heat source. With theproper controls, this configuration can reliably protecta conventional boiler against sustained flue gascondensation.

The possibilities of what can be constructed using thepiping techniques discussed in this section are nearlyendless. The next section will show you how to applythese piping techniques when necessary to createsophisticated multi-load / multi-temperature systems.

Figure 8-13

SECTION

9

DESIGNING MULTIPLE-LOAD

HYDRONIC SYSTEMS

9-1 Introduction

There was a time when residential hydronic heating consisted of 1 to 3 zones of baseboard piped from a singleboiler. Space heating was always considered the main load. Domestic hot water was sometimes provided using atankless coil suspended in a boiler that had to remain hot 24 hours a day, 365 days a year.

Today, residential and light commercial hydronic systems are often more sophisticated than those used in largerbuildings. In addition to multiple methods of space heating, these systems almost always provided domestic hotwater heating. Many go further to provide snow-melting, intermittent garage heating and perhaps even warm thebackyard swimming pool.

This section shows how an integrated multi-load hydronic system can be assembled. It will look at ways toconfigure the heat source, pipe the system and even select control strategies that allow all the loads to operatein an optimal manner.

9-2 Benefits of an Integrated Multi-load System

Hydronic systems are unmatched in their ability to merge several loads into a single “integrated system” in whicha single “heat plant” supplies all loads. This approach increases the duty cycle of the heat plant relative to theindividual duty cycles of several direct-fired appliances. Higher duty cycle yields higher seasonal efficiency andlower fuel consumption.

A single heat plant eliminates the need for multiple dedicated heat sources, each with their own fuel supply,ventilation, exhaust, electrical, space and maintenance requirements.

Since all heat source equipment can be located in one area, service personnel do not have to move throughoutthe building to access it. The mechanical room can be properly vented. The chance of carbon monoxide spillage

99


100

is reduced. Should such spillage occur, there is abetter chance of detecting it prior to its spread throughthe building.

The heat plant used in most integrated multi-loadhydronic systems is one or more gas- or oil-firedboiler(s). Water in the temperature range of 180 to 200degrees F. is produced for loads such as fin-tubeconvectors and domestic water heating. Medium andlow temperature water for other loads is achieved byblending hot water with cooler return water using oneor more of the mixing strategies discussed in section 6.

Integrated multi-load hydronic systems can also takeadvantage of load diversity. It’s the concept that allloads in a multiple load system almost never demandfull heat input at the same time. Thus, it’s almost nevernecessary to size the heat plant equal to the total of allloads operating simultaneously at maximum output.

In the unlikely event all loads did call for maximumheating at the same time the system’s controls caninvoke prioritized load shedding. Heat input to lowerpriority loads like garage floor heating and pool heatingcan be temporarily interrupted so heat can beredirected to higher priority loads like domestic hotwater production and space heating. When the highpriority loads are satisfied, heat output is directed to

making up the heat deficits of the low priority loads.

The large thermal mass of slab-type floor heating andswimming pools make boiler sizing more a matter ofhow much energy can be delivered over a period ofseveral hours, rather than how much instantaneouscapacity is available.

9-3 Multiple Boiler Systems

In some multi-load systems, a single boiler can supplyall the loads. For larger capacity systems (or systems inwhich the load can change dramatically from oneminute to the next) a multiple boiler system is an idealsolution.

Boilers attain their highest efficiency when runningcontinuously. Multiple boiler systems in which eachboiler is individually controlled as a “stage” of heatinput encourage longer on-cycles for the individualboilers and thus higher overall heat plant efficiency.The owner is also likely to save thousands of dollarsover the life of the system because of this higherefficiency. Longer duty cycles also yield longer life andreduced maintenance for components such as hotsurface igniters, oil burners and relays.

Other benefits of multiple staged boiler systems

Figure 9-1

101

include:

• The ability to provide partial heat delivery if oneboiler is down for servicing.

• The use of smaller/lighter boilers that are easierto install, especially in retrofit situations.

• The ability to place all the heat generation in one location and thus eliminate several other dedicated heat sources distributed through thebuilding.

To achieve maximum efficiency, the multiple boilersystem should be designed so heated water is NOTcirculated through unfired boilers. Doing so uses theunfired boiler(s) as heat dissipaters. Although there areseveral possible ways to achieve this, the piping shownin figure 9-1 is considered by many to be the simplestand most efficient approach.

In this configuration, each boiler’s circulator operatesonly when that boiler is firing. The flow check valvesprevents gravity circulation or reverse flow at all othertimes.

This arrangement also supplies each boiler with the

same (lowest possible) return temperature. The coolereach boiler operates, the higher its efficiency. Systemcontrols are configured to prevent any of the boilersfrom operating at temperatures low enough to causesustained flue gas condensation.

Multiple-boiler systems are usually operated by astaging control. Such controls have the ability todetermine the appropriate water temperature for theload(s) that are active at any given time, and then steerthe water temperature supplied to the distributionsystem toward this “target” temperature.

For space heating loads the water temperature is oftenreset based on outdoor temperature as discussed insection 6. When the load is supplied through a heatexchanger (such as with snow melting, pool heating, ordomestic water heating), the control is usuallyconfigured to deliver a high (but fixed) water temper-ature regardless of the outdoor temperature.

Figure 9-2 shows how a 3-boiler system can be pipedto provide heat to both domestic water heating andspace heating loads.

Notice the closely-spaced tees that connect the boiler


Figure 9-2


102

manifold piping to the distribution system. This pipingarrangement allows the boiler system to “hand off”heat to the distribution system without interferencebetween the various circulators.

Also notice the placement of the supply temperaturesensor for the boiler staging control. This placement isnecessary because the boiler circulators will onlyoperate when the boilers are being “called for” by theboiler staging control. Do not place the supply sensoron the boiler manifold piping since there will be timeswhen the boiler circulators will be off, yet a load stillexists in the distribution system. Without flow throughthe boiler, manifold piping heat cannot be delivered tothe distribution system.

9-4 Providing Domestic Hot Water

Most integrated multi-load hydronic systems supplydomestic hot water using an indirect water heater.Upon a call for domestic water heating, hot boilerwater is circulated through a heat exchanger built intothe hot water storage tank.

One method of piping an indirect water heater is as asecondary circuit to a primary loop as shown in figure9-3A.

If this arrangement is used, the DHW tank should bethe first secondary circuit connected to the primaryloop. This provides the hottest water to the tank’s heat

exchanger for fast recovery.

Always install a flow-check valve in the supply lineleading to the tank’s heat exchanger. This prevents thepossibility of heat migration due to buoyancy forcesand/or slight pressure differentials between the closely-spaced tees connecting the tank’s heat exchanger tothe primary loop. It also prevents hot water in the tankfrom establishing a convective cooling loop when thecirculators are off.

Piping the DHW tank as a secondary circuit requireshot water to flow around the entire primary loopwhenever there’s a call for domestic water heating. Tominimize piping heat loss, this piping arrangementshould only be used for short primary loops that runwithin the mechanical room. Preferably, the primaryloop and DHW secondary loop piping will be insulatedto further reduce piping heat loss.

The system designer should also take note that if theDHW tank is not operated as a priority load, alldownstream secondary circuits will receive reducedwater temperature while the DHW load is operating.The heat emitters in the downstream secondary circuitsshould be sized to accommodate this reduced watertemperature if extended demand for domestic waterheating is likely to occur simultaneously with maximumspace heating demand.

Another piping option for connecting an indirect water

Figure 9-3A

103

heater into the system is shown in figure 9-3B.

The indirect water heater is now connected as aparallel circuit to the primary loop. It can operateindependently of the primary loop. If the water heateris located close to the boiler and the piping circuitbetween the two is short, piping heat loss during theDHW cycle is minimal. Furthermore, this arrangementdoesn’t reduce the water temperature supplied to theprimary loop should that loop be operating simultane-ously with domestic water heating. Because of theseadvantages, the parallel piping arrangement is oftenpreferred over piping the indirect water heaters as asecondary circuit.

9-5 Adding Space Heating Loads

Most modern integrated multi-load hydronic systemsare configured around a primary/secondary piping

system. The details and options available forprimary/secondary piping were discussed in section 8.

The backbone of the system is the primary loop. Itconveys hot water to one or more secondary circuitsthat, in turn, convey that water to the heat emitters.Each secondary circuit can be thought of as asubassembly that is “plugged into” the primary loop.

When the system serves several loads that operate overa wide range of water temperatures, the loads requiringthe high water temperatures should be piped in nearthe beginning of a series-type primary loop, while thoserequiring lower temperatures are connected near theend. This allows the loads to accommodate thedecreasing water temperature around the primary loop.

Designers should investigate the possibility ofoperating primary loops with temperature drops of 30to 40 degrees F. under design load conditions, (instead


Figure 9-3B


104

of the typical 20 degrees F.). The greater the temper-ature drop, the lower the primary loop flow rate can beto deliver all the output of the heat source. In manycases the size of the primary loop piping as well as theprimary circulator can be reduced when the loop isdesigned around a higher temperature drop. A smallercirculator could significantly reduce the electricalenergy used by the system over its lifetime.

When designing a series primary loop, it’s necessary toaccount for the temperature drop associated with eachoperating secondary circuit. Formula 8-1, repeatedbelow, can be used for this purpose.

Where:

∆T = Temperature drop in the primary loop acrossthe tees of an operating secondary circuit (deg. F)

Q = Rate of heat delivery to the secondary circuit (Btu/hr)

The heat emitters in the various secondary circuitsneed to be sized for the water temperature available tothem based on where they connect to the primary loop.The farther downstream a given secondary circuitconnects to the primary loop, the lower the watertemperature available to it (assuming the upstreamsecondary circuits are operating).

If a conventional boiler is used as the heat source, thedesigner should also verify that the water temperatureat the end of the primary loop (when all loads areoperating) is high enough to prevent sustained flue gascondensation within the boiler or its vent piping. Referto section 5 for a more detailed discussion of thistopic.

Figure 9-4 depicts a system using a single boiler tosupply radiant floor heating as well as an indirect waterheater. The floor heating system consists of threemanifold stations piped in parallel. This arrangementsupplies the same water temperature to each manifoldstation (as discussed in section 8). The supply watertemperature to the floor circuits is controlled by avariable speed injection mixing system.

Note that the DHW tank is connected as a parallel

∆T = Q500 x f

Formula 8-1

Figure 9-4

f = Flow rate in the primary circuit (in gpm)

500 a constant for water (use 479 for 30% , and450 for 50% glycol)

105

circuit to the primary circuit. Also note the locations ofthe temperature sensors providing feedback to theinjection controller.

Figure 9-5 expands the system of figure 9-4 by addinga series of secondary circuits supplying finned-tubebaseboard. Since the baseboards need to operate at ahigher water temperature than the floor heatingcircuits, the secondary circuit supplying them isconnected to the primary loop upstream of theinjection mixing system.

The distribution system is further expanded in figure 9-6 by adding a heat exchanger to supply heat to agarage floor heating subsystem that will be filled witha glycol solution allowing it to be completely turned offwhen desired.

The temperature of the glycol solution is controlled bya variable speed injection pump that regulates the hotwater flow through the “hot” side of the heatexchanger. The controller operating the injection pumpmonitors its own return temperature sensor locatednear the inlet of the boiler. When necessary, this

controller reduces the hot water flow through thegarage heat exchanger to prevent the cold garage floorslab from removing heat from the system faster thanthe heat plant can produce it.

The heat exchanger, like the DHW tank, is connectedas a parallel (rather than secondary) circuit. In theevent the heat exchanger and the DHW tank areallowed by the controls to operate at the same time,this arrangement makes the highest water temperaturein the system available to both loads.

When the DHW tank or garage floor heat exchanger callfor heat, (as evidenced by a contact closure of either athermostat or aquastat) the boiler staging controlreceives a “setpoint demand.” In this mode, thetarget water temperature leaving the boiler manifoldpiping is typically in the range of 200 deg. F.

When either of the space heating loads calls for heat,the boiler controller receives a “heating demand.” Inthis mode, the target water temperature is calculatedby the boiler control based on the current outdoortemperature (e.g. outdoor reset control).


Figure 9-5


106

Figure 9-7 adds one more subassembly to the system.It’s a secondary circuit consisting of a small circulatorand homerun manifold station supplying several smallheat emitters. Some of these heat emitters may betowel warmers in the building. Others may supplementthe output of a heated floor in certain high load areasof the building.

The home run approach as described in section 6allows small diameter Kitec or PEX tubing to be routedthrough the building structure much like electricalcable. It also allows for individual circuit control andsupplies the same water temperature to each circuit.

Another modification shown in figure 9-7 is using anexternal stainless steel heat exchanger between thesystem water and a conventional hot water storagetank. A stainless steel or bronze circulator must beused between the storage tank and the heat exchanger.

This arrangement can be used in situations where theheat transfer capacity of an indirect water heater (withits own internal heat exchanger) is not sufficient to

transfer the full heat output of the heat plant to thedomestic hot water load. When heat transfer betweenthe heat plant and domestic hot water load is “bottle-necked”, the boiler will climb to its high limit temper-ature before the DHW load is satisfied and shut offduring part of the cycle. As such, the heat plant is notdelivering its full potential heat output rate to the load.Ensuring that this doesn’t happen is important insystems that supply domestic hot water to homes withmultiple bathrooms, especially those equipped withhigh water usage fixtures.

9-6 Summary of Design Concepts

Here’s a summary of the concepts to remember whendesigning multi-load hydronic systems:

• Use a single “heat plant” to supply all heatingloads rather than using several “dedicated” heat sources.

• Examine load diversity when sizing the heatingplant. Consider the likely total heat needed by

Figure 9-6

107

the loads over a period of several hours. Use prioritized load shedding (when necessary) to handle unusually high load requirements.

• Use a multiple boiler system rather than a single large boiler when the system has a widerange of load requirements (such as a high intermittent demand for domestic water heating).

• When using multiple boilers, configure the piping and controls so heated water is not circulated through unfired boilers.

• When using multiple boilers, connect the boiler manifold to the distribution system witha pair of closely-spaced tees to prevent inter-ference between the boiler circulators and those in the distribution system.

• Use a series primary loop when the water supply temperatures of the secondary loads varyover a wide range.

• Connect high temperature secondary circuits near the beginning of a series primary loop, and lower temperature loads near the end.

• Use a parallel primary secondary piping when the water supply temperatures of the secondarycircuits are all similar.

• To minimize piping heat loss connect the indirect DHW tank as a parallel (rather than secondary) circuit.

• To reduce pipe size, pump size and operating cost, consider designing series-type primary loops for a temperature drop of 30 to 40 degreeF. under full load.

• For maximum recovery rate, ensure that the full output of the heat plant can be delivered tothe water heater without the boilers reaching their high limit temperature settings. Use an external heat exchanger if necessary to ensure full heat transfer to the domestic hot water storage tank.


Figure 9-7

SECTION

10

RADIANT PIPE AND TUBING

IPEX is a leading supplier of thermoplastic piping systems, providing customers with one of the world’s largestand most comprehensive product lines. Included in this offering are the two leading products for hydronic radiantheating – Kitec XPA pipe and oxygen barrier PEX tubing.

Kitec XPA and PEX tubing have each played an important role in the impressive growth of hydronic radiant systempopularity in North America. Used in radiant floor heating for residential, industrial and institutional projects,radiator and baseboard hook-up, snowmelt systems and more, XPA and PEX transport liquid from heat source, toheat zone and back again.

But why choose PEX tubing for a given radiant heating installation instead of XPA pipe? The answer is really basedon personal preference.

Some contractors prefer PEX tubing for staple-up applications between floor joists – stating that PEX tube is moreflexible and less prone to kinking than XPA pipe. Others find smaller 3/8” diameter PEX tube ideally suited fortopping pour installations where floor to ceiling height is limited or were changing the floor elevation is restricted.Some say there is no discernable difference between the two and the matter is cost. Still, others feel that XPApipe is by far the superior pipe for hydronics.

The facts show that both PEX tubing and XPA pipe are viable products with decades of proven performance in allmanner of hydronic applications. As the world’s leading supplier of thermoplastic piping systems, IPEX offersindustry the two leading options for hydronic pipe and tubing. In time, the debate over which is better – XPA orPEX – will sort itself out.

Kitec XPA Pipe

Great ideas are often born by merging the strengths of one product with those of another. Kitec XPA (X-linkedPolyethylene Aluminum) pipe is the result of one of these great ideas. It combines the strength of metal with the

109


110

longevity of plastic – and it brings some uniquebenefits to the hydronic radiant heating market.

XPA’s aluminum core is what sets it above all otherheating pipes. In combination with x-linkedpolyethylene and specialized adhesive layers that bondthe components together, this aluminum core isresponsible for most of XPA pipe’s unique features andbenefits.

Thanks to its aluminum core, XPA pipe is stronger thantypical heating PEX tubing. XPA pipe exhibits greaterlong term pressure ratings (25% higher operatingpressure than PEX tube), greater burst pressure resis-tance, greater hoop strength for resistance to crushing,greater beam strength for less sagging.

Oxygen Barrier PEX Tubing

PEX tubing is universally recognized as the most widelyused radiant heating tube. Its light weight, flexibilityand wide availability make it a natural choice forradiant heating applications.

IPEX offers a full range of oxygen barrier PEX tubingsizes to round out its industry leading offering ofWarmRite Floor hydronic radiant heating components.PEX manifold fittings are designed to quickly andeasily connect PEX tubing to the full range of standardWarmRite Floor chrome manifolds. And pre-assembledWarmRite Floor control panels accept PEX tubing aswell.

In order to facilitate a technical comparison betweenXPA pipe and PEX tubing, the following information isarranged to show XPA details along side PEX.

NominalSize

3/8

1/2

5/8

3/4

1

AverageI.D.

0.346

0.500

0.631

0.806

1.032

AverageO.D.

0.48

0.63

0.79

0.98

1.26

Weight lb / 100 ft

4.7

6.8

10.1

13.7

23.0

Volume U.S.gal / ft

0.005

0.009

0.016

0.025

0.040

NominalSize

9

12

16

20

25

AverageI.D.

8.8

12.5

16.0

20.5

26.0

AverageO.D.

12.2

16.0

20.0

25.0

32.0

Weight g / m

69

101

150

203

341

Volumel / m

0.063

0.113

0.201

0.314

0.500

NominalSize

3/8

1/2

5/8

3/4

1

AverageI.D.

0.346

0.485

0.584

0.681

0.875

AverageO.D.

0.500

0.625

0.750

0.875

1.125

Weight lb / 100 ft

4.1

5.4

8.1

10.2

16.9

Volume U.S.gal / ft

0.005

0.009

0.014

0.019

0.030

NominalSize

9

12

16

20

25

AverageI.D.

8.8

12.3

14.8

17.3

22.2

AverageO.D.

12.7

15.9

19.0

22.2

28.6

Weight g / m

61

81

121

152

252

Volumel / m

1.063

0.111

0.174

0.236

0.372

Kitec XPA Pipe

Dimensions in inches

PEX Tubing

Dimensions in inches

Dimensions in mm Dimensions in mm

111

XPA pipe is easily shaped by hand, Keeps its shape

XPA pipe loops can be easily shaped by hand to aradius of 5 times the pipe O.D. And thanks to thealuminum core XPA pipe maintains the shape that youbend it to – this is of great benefit when installingradiant heating loops especially when compared to PEXtubing. Larger pipe sizes may require a bending tool toachieve the minimum radius shown.

When uncoiled, PEX tubing tries to revert back to itssmaller coil size. This makes installation somewhatmore challenging and requires PEX tube to be securedat closer intervals in order to maintain its installedposition. As well, PEX tubing is less malleable thanXPA pipe and therefore has larger allowable bendingradii than XPA.

Oxygen permeation

Unlike barrier PEX tubing with its externally appliedoxygen barrier XPA pipe houses an aluminum oxygenbarrier permanently in between layers of plastic. Thismeans that damage due to installation andconstruction is avoided making the oxygen barrier apermanent and reliable component of your heatingsystem.

XPA pipe limits oxygen permeation to0.006g/m3/ºC/day, 25 times better than the acceptablestandard.

PEX tubing has its EVOH oxygen barrier located on theoutside of the tubing. This layer limits oxygen perme-ation to minimum acceptable amount of 0.10g/m3/ºC/day.

XPA Pipe – built in safety against ground sourcecontaminants

That same aluminum core that provides such anexcellent and permanent oxygen barrier, acts as a firstline of defense against ground source contaminationsuch as termiticide. IPEX XPA pipe can be burieddirectly below grade and in the slab without fear ofground source contamination.

PEX tubing should be treated as a thermoplastic pipingmaterial in relation to its permeability. Thermoplasticsystems including PEX should not be used if groundsource contamination is a threat.

Low Expansion and Contraction

The coefficient of linear expansion for XPA pipe is verysimilar to copper – 1.3 x 10-5 in./in./ºF(0.23mm/10m/ºC). As an example, one hundred feet ofXPA pipe with a 10ºF rise in temperature will expandonly 0.156 inches.

PEX tubing on the other hand has a linear expansion /contraction 7 times greater than XPA pipe. Onehundred feet of PEX tubing expands and contracts at arate of 1.1 inches per 10ºF change in temperature.

The following charts provide a quick reference forexpansion / contraction of 100 feet (30.5m) of KitecXPA pipe and PEX tubing.

SECTION 10 RADIANT PIPE AND TUBING

in

3/8

1/2

5/8

3/4

1

mm

9

12

16

20

25

in

2.5

3.2

4.0

5.5

6.5

mm

64

81

102

140

165

in

3.0

3.8

4.5

7.0

9.0

mm

76

97

114

178

229

Nominal PipeSize

XPA Pipe Min. Bend Radius

PEX Tubing Min. Bend Radius

ºFºC

in

mm

20ºF(-7C)

-0.80

-20

40ºF(4C)

-0.48

-12

60ºF(15C)

-0.16

-4

70ºF(21C)

100.0’

30.5m

80ºF(27C)

+0.16

+4

100ºF(38C)

+0.48

+12

120ºF(49C)

+0.80

+20

140ºF(60C)

+1.12

+28

160ºF(71C)

+1.44

+36

180ºF(82C)

+1.76

+44

200ºF(93C)

+2.08

+52

ºFºC

in

mm

20ºF(-7C)

-5.5

-140

40ºF(4C)

-3.3

-84

660ºF(15C)

-1.1

-28

70ºF(21C)

100.0’

30.5m

80ºF(27C)

+1.1

+28

100ºF(38C)

+3.3

+84

120ºF(49C)

+5.5

+140

140ºF(60C)

+7.7

+196

160ºF(71C)

+9.9

+252

180ºF(82C)

+12.1

+308

200ºF(93C)

+14.3

+364

Approximate linear expansion / contraction of 100 feet of XPA pipe

Approximate linear expansion / contraction of 100 feet of PEX Tubing


112

Less head loss than equivalent PEX tube

The following table provides a head loss comparison between Kitec XPA Pipe and PEX Tubing. The larger I.D. ofXPA is clearly evident in the following table. Detailed flow rate tables for various heating mediums and temper-atures are included in the Appendices.

0.110.450.921.522.243.083.614.585.666.849.48

12.5015.9019.6023.7035.5049.20

--

0.020.050.160.260.390.540.700.890.971.171.622.142.723.364.066.068.41

11.1014.10

0.010.020.030.090.130.170.230.291.360.430.520.690.881.081.311.962.713.584.55

0.000.010.010.010.040.060.070.090.110.140.190.240.280.340.410.610.851.121.43

0.000.000.000.010.010.020.020.030.030.040.060.080.100.120.130.190.260.340.44

0.110.450.921.522.243.083.614.585.666.849.48

12.5015.9019.6023.7035.5049.20

--

0.030.060.180.300.450.620.811.031.151.391.922.543.223.984.817.189.96

13.1016.70

0.010.030.040.130.190.260.340.420.520.630.771.021.291.601.932.883.995.276.70

0.010.010.020.060.090.120.160.200.250.300.420.490.620.760.921.381.912.523.20

0.000.010.010.010.030.040.050.060.080.090.130.170.190.230.280.410.570.760.96

XPA PipePressure Loss per 100 feet - psi

PEX TubingPressure Loss per 100 feet - psi

Flow RateGPM

3/8" 1/2" 5/8" 3/4" 1" 3/8" 1/2" 5/8" 3/4" 1"

0.10.20.30.40.50.60.70.80.91.01.21.41.61.82.02.53.03.54.0

2.4110.220.734.350.769.781.710412815521528336044

537802

1110--

0.551.113.615.978.8212.115.920.121.926.536.748.461.576.091.8137190251319

0.220.430.651.952.883.965.186.558.059.6811.915.619.924.529.644.261.481.0103

0.080.160.250.330.911.261.652.082.553.074.225.536.247.719.31

13.9019.3025.4032.30

0.030.060.090.120.150.390.510.640.790.951.311.712.162.663.194.255.897.779.87

2.4110.220.734.350.769.781.7105128155215283360444537802

1110--

0.971.932.907.7411.415.720.626.032.038.552.963.380.499.2120179248327416

0.300.590.892.854.225.87.69.6

11.814.217.523.029.236.143.665.190.3119151

0.160.320.481.382.032.803.664.635.696.849.4111.014.017.320.931.243.257.072.5

0.060.120.180.240.620.851.111.411.732.082.863.754.215.206.289.3713.017.121.8

XPA PipePressure Loss per 100 meters - kPa

PEX TubingPressure Loss per 100 meters - kPa

Flow RateL / min

9mm 12mm 16mm 20mm 25mm 9mm 12mm 16mm 20mm 25mm

0.390.781.171.561.952.332.723.113.503.894.675.456.227.007.789.73

11.7013.6015.60

113

Larger inside diameters

XPA pipe has larger inside diameters than the compa-rable nominal size PEX tubing.

Rates of Thermal Conduction

Due to its aluminum and plastic construction, XPA pipehas a greater rate of thermal conduction than does PEXtubing. The following chart defines values for both XPAand PEX.

High pressure ratings

IPEX XPA pipe provides 25% greater long termpressure rating than typical PEX tubing. XPA is ratedfor continual service of 200 psi at 73ºF and 125psi at180ºF. PEX tubing is rated for continual service of 160psi at 73ºF and 100psi at 180ºF. XPA also offersexcellent resistance to quick burst conditions as shownin the following table.

Quick Burst Pressures – XPA Pipe

Resistance to damage from freezing

Good installation practice dictates protection againstfreezing for piping systems. However, in the event thatfreezing does occur, XPA pipe does provide a level ofsafety against pipe burst when installed in open free airconditions. Tests show that IPEX XPA pipe may take upto 5 freeze thaw cycles before failing. Compared totraditional metal pipes XPA provides you with morebuilt in peace of mind.

When encased in concrete however, the extreme forcesof freezing water against cured concrete leave littlechance for any pipe including XPA to survive. Caremust always be taken to avoid freezing of hydronicpiping installed in slabs.

Flame Spread and Smoke Ratings

XPA pipe has a Flame Spread Rating of 5 and a SmokeDevelopment Rating of 5 as per third party testing toULC-S102.2. This allows it to be used in high-riseconstruction as well as in return air plenums andvertical shafts. Check with the local authority havingjurisdiction.

PEX tubing also meets certain building code guidelinesfor use in combustible construction – contact yourIPEX representative for more details.

Firestopping XPA Pipe

XPA pipe has been tested and listed with variousfirestopping materials in accordance with CAN/ULCS115-M95, ASTM E81 and UL 1479. Approved andlisted firestop materials are available from 3M (CP25WB or Silicone 2000), PFP Partners (4800 DW) andJohns Manville (Firetemp Cl).

In the event that XPA pipe must penetrate a fire ratedwall, these firestop materials may be used to maintainthe assembly rating. IPEX XPA pipe and firestopproducts must be installed in accordance with theindividual product listing to ensure proper perfor-mance. Contact IPEX for detailed instructions.

Electrical Properties

Although XPA pipe contains an aluminum core, itsjoining systems are not designed to conduct straycurrent. In consideration of electrical grounding XPApipe is considered to be a thermoplastic piping systemand should never be used to ground.

PEX tubing too should be treated as other thermo-plastic piping systems are in that it must not be usedto ground electrical systems.

SECTION 10 RADIANT PIPE AND TUBING

3/8"(9mm)

1160 psi(8004kPa)

750 psi(5175kPa)

1/2"(12mm)

1015 psi(7003kPa)

685 psi(4724kPa)

5/8"(16mm)

1005 psi(6935kPa)

655 psi(4520kPa)

3/4"(20mm)

825 psi(5693kPa)

550 psi(3795kPa)

1" (25mm)

790 psi(5451kPa)

535 psi(3692kPa)

QuickBurst73ºF

(23ºC)

QuickBurst180ºF(82ºC)

in

3/8

1/2

5/8

3/4

1

mm

9

12

16

20

25

in

0.346

0.500

0.637

0.806

1.032

mm

8.8

12.7

16.2

20.5

26.2

in

0.346

0.485

0.584

0.681

0.875

mm

8.8

12.3

14.8

17.3

22.2

Nominal Size XPA Pipe Actual I.D.

PEX Tubing Actual I.D.

in

3/8

1/2

5/8

3/4

1

mm

9

12

16

20

25

ºF

0.329

0.457

0.578

0.725

0.927

ºC

0.570

0.791

1.000

1.255

1.605

ºF

0.290

0.377

0.454

0.530

0.681

ºC

0.502

0.653

0.785

0.917

1.179

Nominal PipeSize

XPA Pipe BTU/h/ft/ºF W(m.ºC)

PEX Tubing BTU/h/ft/ºF W(m.ºC)


114

XPA Pipe and Fitting Standards

IPEX manufactures and carries third party certificationon XPA pipe to the following standards:

CAN / CSA B137.9Standard for Crosslinked Polyethylene / Aluminum /Crosslinked Polyethylene Composite Pressure PipeSystems

ANSI/ASTM F1281Standard Specification for Crosslinked Polyethylene /Aluminum / Crosslinked Polyethylene (PEX-AL-PEX)Pressure Pipe

These standards include requirements for pipe sizes,dimensions, workmanship, quality control, burst andsustained pressure performance and more.

ANSI / ASTM F1974Standard Specifications for Metal Insert Fittings forPolyethylene / Aluminum / Polyethylene andCrosslinked Polyethylene / Aluminum / CrosslinkedPolyethylene Composite Pressure Pipe

This standard includes requirements for IPEX K1compression style fittings and K2 crimp style fittings.The standard outlines acceptable fitting materials,dimensional requirements, short term burst and longterm pressure ratings, etc.

Mechanical and Building Code Compliance

XPA pipe and fittings are recognized and included inthe National Plumbing and Building Codes of Canadaas well as in the National Hydronic Standard ofCanada.

In the United States XPA pipe and fittings are includedin the Uniform Mechanical Code and the InternationalPlumbing, Mechanical and Residential Codes.

PPI TR-4PPI Listing of Hydrostatic Design Bases andMaximum Recommended Hydrostatic Design Stressesfor Thermoplastic Pipe Materials

IPEX XPA pipe is listed with PPI for the followingpressure and temperature ratings:

200psi at 73ºF 125psi at 180ºF

ANSI / NSF 14Plastics Piping System Components and RelatedMaterials Product Certification Listing

IPEX holds NSF certification on its XPA pipe forpotable water applications and radiant floor heating inresidential and commercial construction, includingmanufactured housing.

PEX Tubing Standards

IPEX offer CTS SDR-9 PEX tubing manufactured andthird party certified to the following standards:

CAN/CSA B137.5Standard for Crosslinked Polyethylene PressureTubing Systems

ASTM F876Standard Specification for Crosslinked Polyethylene(PEX) Tubing

ASTM F877Standard Specification for Crosslinked Polyethylene(PEX) Plastic Hot and Cold Water DistributionSystems

PPI TR-4PPI Listing of Hydrostatic Design Bases andMaximum Recommended Hydrostatic Design Stressesfor Thermoplastic Pipe Materials

IPEX PEX tubing is listed with PPI for the followingpressure and temperature ratings:

160psi at 73F 100psi at 180F

ANSI / NSF 14Plastics Piping System Components and RelatedMaterials Product Certification Listing

IPEX holds NSF certification on its PEX tubing forpotable water applications and radiant floor heating inresidential and commercial construction, includingmanufactured housing.

Mechanical and Building Code Compliance

PEX tubing is recognized and accepted in all modelcodes across North America including the NationalPlumbing Code of Canada, the National HydronicStandard of Canada, the Uniform Mechanical Code,the International Plumbing, Mechanical andResidential Codes, and by BOCA and SBCCI.

SECTION

11

HYDRONIC SNOW AND ICE MELTING

11-1 Introduction:

115

IPEX hydronic heating products can be used toprovide snow and ice melting on all types of exteriorareas including:

• Driveways

• Walkways

• Parking areas

• Steps

• Wheelchair access ramps

• Patios

• Decks

• Roofs

On specialized commercial and industrialproperties, hydronic snow melting has been usedfor the following applications:

• Car washes

• Hospital emergency entrances

• Toll booth areas

• Loading docks

• Helicopter landing pads

• Security gate areas

• Other areas that must be kept free of snow and ice


116

11-2 The Benefits

Hydronic snow and ice melting offers many benefitsover traditional methods of snow removal. Theyinclude:

• The capability of providing fully automatic/unattended snow removal whenever required.

• The ability to remove snow without creating banks or piles that subsequently cause drifting,and often damage surrounding landscaping.

• The elimination of sanding.

• The elimination of salting and its potential damage to landscaping and the surrounding environment.

• Less pavement damage due to frost action, chemical deterioration due to salting, and physical damage from plowing. The latter is especially important when paving bricks/tiles are used.

• Cleaner interior floors because sand and salt are not tracked in

• Because all snow and ice is removed, the possibility of slips, falls or vehicular accidents is greatly reduced, especially on sloped pavements. This reduces liability, especially inpublic areas.

• Improved property appearance during winter.

• The ability to use almost any fuel or heat sourceto provide the energy required for melting.

11-3 System Classifications

There are several possible approaches to designing ahydronic snow and ice melting system. They vary inboth the rate of heat delivery to the surface beingmelted, and the type of controls used to initiate andterminate the melting operation.

Over the last few decades the design of snow and icemelting systems has been somewhat loosely classifiedas follows:

Class 1 systems:

This class of system is generally accepted as sufficientfor most residential walkway and driveway areas. Therate of heat delivery to the surface in generally in therange of 80 to 125 Btu/hr/square foot depending onlocation. Class 1 systems often allow a layer of snow toaccumulate during a heavy snowfall, especially if thesystem is manually controlled and starts from cold.This snow layer is actually beneficial because it acts as

an insulator between the heated pavement surface andthe outside air reducing both evaporation andconvective losses. Evaporation of the melt waterrequires much higher heat input.

Class 2 systems:

Generally accepted as sufficient for most retail andcommercial paved areas that must be kept clear ofaccumulating snow during a heavy snow fall, althoughthe pavement will often remain wet. The rate of heatdelivery to the surface in typically in the range of 125to 250 Btu/hr/square foot, depending on location.

Class 3 systems:

Used for high priority areas such as helicopter pads,toll plazas, sloped pavements in parking areas,pavements adjacent to hospital emergency rooms.Class 3 systems are designed with the ability to melt allsnow as fast as it falls and quickly evaporate the meltwater from the surface. They generally require heatdelivery rates of 250 to as high as 450 Btu/hr/squarefoot.

Design Output, Btu/hr/sqft

Albuquerque, NMAmarillo, TXBoston, MABuffalo – Niagara Falls, NYBurlington, VTCaribou – Limestone, MECheyenne, WYChicago, ILColorado Springs, COColumbus, OHDetroit, MIDuluth, MNFalmouth, MAGreat Falls, MTHartford, CNLincoln, NBMemphis, TNMinneapolis – St. Paul, MNMt. Home, IDNew York, NYOgden, UTOklahoma City, OKPhiladelphia, PAPittsburgh, PAPortland, ORRapid City, SDReno, NVSt. Louis, MOSalina, KSSault Ste. Marie, MISeattle – Tacoma, WASpokane, WAWashington, D.C.

7198

1078090938389635269

11493

11211567

1349550

12198669789868698

12285789287

117

821432311921421381291656372

14020614413825420214415590

29821681

22915797

102154152120144128127121

167241255307244307425350293253255374165372260246212254140342217350263275111447155198228213133189144

City Class ISystem

Class IISystem

Class IIISystem

(Permission to use data authorized by ASHRAE)

117

The major distinction between these classes is in therate of heat delivery to the area being melted. Thefollowing table gives suggested heat delivery rates forall three class of snow melting systems in severallocations.

11-4 Tubing Installation Guidelines

This section shows suggested construction details forinstalling Kitec tubing in various snow melting appli-cations. These details have been carefully developed toensure good performance of the system. In some cases,local design practices and code requirements mayrequire them to be modified.

Drainage considerations

It is crucially important that all melted pavement areasbe detailed for proper drainage of melt water. The heatdelivery rates used with Class 1 and 2 systems assumethat most of the melt water will be drained from thesurface (as a liquid) rather than evaporated. The lattermethod of moisture removal requires considerablymore heat input.

Failure to provide proper drainage can allow melt waterto accumulate at low points in the pavement, or wherethe melted pavement adjoins non-melted areas. Whenthe system turns off, this standing water can quicklyturn to dangerous ice.

Pavements must be sloped to drains capable of routingthe melt water to a drywell, storm sewer, or otherdischarge (check local codes) without it freezing in theprocess. Drainage piping should not run through theheated thermal mass because the cold water will robheat from the system. Instead, drainage piping shouldbe routed beneath the underside insulation where it isprotected from freezing. Keep in mind that a shallowdrainpipe running through unheated soil can quicklyfill with ice and be very difficult to thaw. One methodof ensuring the drainage system does not freeze is toinstall a dedicated drain heating circuit of Kitec tubingalongside the drainage trench, receptor and piping.

Trench drain systems are often used at the lower eleva-tions in melted pavements. If the pavement slopestoward a building, be sure the melt water can becollected before it can flow into the building. Likewise,be sure melt water running down a pavement toward astreet will be collected by a drain before it contacts theunheated pavement.

Figure 11-2 shows some examples of pavementdrainage concepts.

Be sure to discuss drainage provisions with thoseresponsible for its installation as soon as possible inthe planning stages of the system.

SECTION 11 HYDRONIC SNOW AND ICE MELTING

sealantoverhead door

gratemelted pavement


trench drain at low point

to drywell

street pavement(unmelted)melted pavement


trench drain

to drywell Figure 11-2


118

Evaluating Sub-surface Conditions:

When planning a snow melting system, the designershould always evaluate the soils under the area to bemelted. Failure to address subsoil problems can lead tounanticipated conditions that will not only damage thepavement, but could also severely damage the tubing.

If the local water table is within 3 feet of the surface,it has the potential to greatly increase downward heatloss from the melted pavement. Such situations requireproper subsoil drainage to lower the water table. Aproperly detailed “French drain” constructed aroundthe perimeter of the paved area is a typical solution.

If bedrock is present under the area to be melted, it’simperative to slope or channel the rock surface so anywater percolating down from the melted surface can bedrained away. Otherwise, the bedrock may pond waterunder the melted pavement. It’s also crucial to installa minimum of 1 inch of extruded polystyrene insulationto reduce heat conduction to the bedrock.

Low percolation soils containing high amounts of clayor silt retain moisture in winter. When these (saturated)soils freeze, the expanding ice crystals create powerfulforces that can easily crack and heave pavementsupward. If such soils are present, the base layer of thepavement system should consist of 6 to 9 inches of #2size crushed stone. The soil surface beneath the stonelayer should be sloped so any water reaching the stonelayer can be collected and drained away. The stonelayer should also be tamped to form a flat surface forthe insulation board installed above it.

When pavements are to be placed over areas ofdisturbed or otherwise unstable soil, a geotextile fabricshould be incorporated into this base layer. This verystrong non-deteriorating fabric helps spread high loadsover larger areas to prevent eventual depressions in thepavement. Such depressions could eventually damageembedded tubing.

Remember—no snow melting system can make up forpoor pavement design. Be sure to involve knowl-edgeable professionals in the pavement planningprocess.

Installation Procedure for Concrete Pavements

Figure 11-3 shows the material assembly used for atypical snowmelting system in a concrete driveway orwalkway.

When the local soil has good drainage characteristics,the base layer generally consists of 6 to 9 inches ofcompacted gravel. Moisture that may eventuallypercolate down to this layer will pass through into thesubsoil below. In some cases, a geotextile fabric will beincorporated into this base layer to further stabilize it.

In cold climates or projects where the pavement will beheld at an “idling” temperature near freezing, it is costeffective to install a layer of extruded polystyreneinsulation over the compacted gravel base. Thisinsulation greatly reduces downward heat loss from thepavement. It also shortens the response time of thesystem when melting is required, especially in coldclimates where the system doesn’t idle the slab.

A thickness of 1 inch (R-5) is usually adequate. Besure the rigid board insulation lies flat against thecompacted gravel base at all locations so the pavementis fully supported when loaded.

The compressive stress rating of the insulation shouldbe selected to match loads that may be imposed on thepavement. A 25 psi rated insulation board is theminimum rating for pavements subject to lightvehicular traffic. If heavier (truck) traffic is anticipatedinsulation with a compressive load rating of 40 to 60psi should be considered. Insulation manufacturerscan provide guidance on the proper compressive stressrating for a given pavement application.

Welded wire fabric (WWF), or a grid of rebar is nowinstalled over the insulation. Be sure to overlap allsheets of WWF by at least 6” and tie them togetherwith wire twist ties.

The Kitec tubing can now be secured to the steelreinforcing using wire twist ties spaced 48 to 60 inchesapart.

Tube spacing should never exceed 12 inches. Widerspacing can result in uneven melting patterns that maynot completely clear the pavement of snow before themelting operation is shut off. Nine inch tube spacing isrecommended in most cases. In areas with high snowfall rates, high average wind speeds or situations wherea cold (non-idled) slab needs to be brought up totemperature quickly, 6 in. spacing should be used.Section 11-6 discusses tube spacing issues in moredetail.

Tubing circuits should be planned so as not to exceedthe maximum lengths given in section 11-6. Thewarmest portion of the circuit should generally berouted in the areas with the highest melting priority.For example, the tire track area of a typical drivewaywould usually have a higher melting priority than theedges of the driveway. Don’t install tubing closer than6 inches to the edge of the pavement.

119


concrete paving

pipe

wire mesh

insulation

compacted base

SNOWMELT CONCRETE SLAB

heavy duty extrudedpolystyrene

Figure 11-3A

Figure 11-3


120

Figure 11-4 shows a typical tubing layout for aresidential driveway based on use of 5/8” Kitec pipe.

It is highly recommend that the designer make anaccurate tubing layout drawing for each project beforeinstallation begins. CAD generated tubing layouts allowthe designer to check circuit lengths, determine thetotal amount of tubing needed and provide the installerwith an easy to follow plan.

Once installed, all tubing circuits should be pressuretested using compressed air at 75 psi for a minimumof 24 hours prior to placing the concrete.

Be sure to cap all circuit ends until they are connectedto the manifold to prevent construction dust andmoisture from contaminating the system.

The tubing and reinforcing steel should be supportedor lifted during the pour so the top of the tubing is 1.5to 2 inches below the finish surface of the slab. Tubing

depth is more critical in a snow melting applicationsthan in radiant floor heating. Leaving the tubing at thebottom of a typical 6” exterior slab significantlyincreases the response time of the system whenmelting is initiated. It also increases the required fluidtemperature and downward heat loss.

The tubing should be protected with sleeving whereverit crosses a full control joint location in the slab. Thetubing depth should be sufficient to ensure that sawncontrol joints will not harm the tubing, no sleevingnecessary. In locations where the tubing passes fromthe paved area through a foundation wall, the instal-lation must be detailed to prevent damage to thetubing should the pavement shift up or down.

Air entrained concrete with a minimal 28 daycompressive stress rating of 4000 psi is often specifiedfor exterior slabs.

Figure 11-4

121

Installation Procedure for Asphalt Pavements

Figure 11-5 shows the material assembly used for atypical snow melting system in asphalt paved drivewaysor walkways.

The subgrade and insulation under an asphalt drivewayor walkway is prepared the same as for a concretepavement. A mat of welded wire fabric (WWF) is thenlaid out over the insulation. All sheets of the WWF

SESECTION 11 HYDRONIC SNOW AND ICE MELTING

compacted sandpipe

wire mesh

insulation

compacted base

SNOWMELT ASPHALT PAVING

heavy duty extrudedpolystyrene

asphalt paving

Figure 11-5A

Figure 11-5


122

should be overlapped 6 inches at their edges and tiedtogether with wire twist ties. The tubing is unrolled andsecured to the WWF with wire twist ties spaced 48 to60 inches apart.

After pressure testing the circuits a 3 to 4 inch deeplayer of sand or stone dust is placed over them. Thesand/stone dust layer protects the tubing from the hotasphalt (250-350 degrees F.). After the WWF andtubing have been placed, the sand/stone dust shouldbe uniformly and thoroughly soaked with water to settlethe particles around the tubing and provide a stablebase for the asphalt.

Kitec (PEX-AL-PEX) pipe is especially well suited to thisapplication because its low coefficient of expansionminimizes dimensional changes of long tubing runs asthe system cycles between warm and cold.

When placed, asphalt paving can be as hot as 350degrees F. It should never be placed directly on Kitecor PEX tubing. However, when the tubing is embeddedin the layer of sand/stone dust as described, the hotasphalt can be placed without damaging to the tubing.

Installation Procedure for Surfaces Covered withPaving Stones

Pavements consisting of loosely laid (non-mortared)paving bricks or tiles are easily damaged by conven-tional methods of snow removal and therefor wellsuited to hydronic snow melting.

Figure 11-6 shows the material assembly used for atypical snow melting system for an area finish withpaving bricks or stone.

Unlike concrete or asphalt, paving bricks allow water toseep down between individual units. This water cannotbe allowed to accumulate under the pavers becausesubsequent freezing can cause the pavers to heaveupward.

In areas with low permeability soil, the base layerbelow the insulation should be detailed for efficientdrainage. A 6 to 9 inch deep layer of #2 crushed stoneplaced over a slightly sloping grade allows verticaldrainage of water. The crushed stone base layer mustitself be drained to either a drywell or other suitable

Figure 11-6

123

discharge area. The crushed stone layer should also betamped flat before the rigid insulation is placed over it.

Drainage detailing is still recommended since the rateof melt water (or rainwater) accumulation may at timesexceed the rate at which water can weep downwardbetween the pavers.

Extruded polystyrene insulation is impermeable towater. To allow water drainage, nominal 1/2” gapsshould be left between adjacent sheets of insulation.Alternatively, several sheets of rigid insulation can bestacked and drilled to form a grid of 1 inch diameterholes space 12 inches apart. In either case, the holesor slots must be covered with strips of water permeable“filter fabric.” This allows water to drain throughwithout carrying the fine particles of sand or stone dustwith it. Avoid creating drainage situations whereflowing water could form channels through thesand/stone dust layer beneath the pavers. Suchchannels could lead to voids that may eventually causesome pavers to sink.

A mat of welded wire fabric (WWF) is laid out over theinsulation. All sheets of the WWF should be overlapped6 inches at their edges and tied together with wire twistties. The tubing is then unrolled and secured to theWWF with wire twist ties spaced 48 to 60 inches apart.

After the tubing circuits have been pressure tested,the tubing and WWF should be covered with 3 to 4inches of sand or stone dust. After the WWF and tubinghave been layered the sand layer should be uniformlyand thoroughly soaked with water to settle the sand orstone dust around the tubing and provide a stable basefor the pavers.

11-5 Controlling Snow Melting Systems

There are several ways to control snow-meltingsystems. They differ in their ability to detect when

melting is required, as well as how they control thepavement temperature before, during and after meltingoperation. They also differ considerably in cost. Theapproach selected must be based on the expectation ofthe owner, the degree of unattended operationexpected, the size of the area being melted and theclass of system being designed.

Regardless of the control method used, some funda-mental issues must be understood before a snowmeltsystem can be properly designed:

Antifreeze Issues

Some snow melting systems use a dedicated boiler astheir heat source. The boiler and distribution piping isusually filled with an antifreeze solution (typically a 30to 50% mixture of propylene glycol and water).

In other systems snow melting as one of several loadsserved by the same boiler(s). The boiler(s) and pipingthat’s are not part of the snow melting system are filledwith water. In this case, a heat exchanger must beinstalled to isolate the antifreeze solution in the snowmelting distribution system from the remainder of thesystem. A stainless steel plate type heat exchanger isoften used for such applications.

The freezing point of the mixture is a function of the %and type of glycol used. The following table helpsselect the correct mixture based on the outdoortemperature.

When the system starts with a cold boiler it may bepossible for very cold antifreeze returning from theexterior circuits to flow through the heat exchanger


compacted sandpipe

wire mesh

insulation

compacted base

SNOWMELT PAVING STONES

heavy-duty extrudedpolystyrene

paving bricks

Figure 11-6A

10% 20% 25% 30% 35% 40% 45% 50% 55%

27°F 19°F 15°F 8°F 0°F -3°F -15°F -28°F -40°F

27°F 18°F 10°F 5°F -2°F -10°F -20°F -33°F -50°F

Glycol %

Propylene

Ethylene


124

before much heat is delivered from the boiler to theheat exchanger. This, combined with the fact that plateheat exchangers are very efficient and have littlethermal mass, presents the possibility of freezing thewater in the hot side of the exchanger before heat canbe delivered from the boiler.

To avoid this possibility, use a temperature control tosense that hot water is flowing through the heatexchanger before allowing the circulator in the snowmelting distribution system from operating. Some snowmelting system controllers may have this capabilitybuilt into them.

Boiler Issues

Section 3 described the necessity of maintaining theinlet temperature to a conventional boiler high enoughto prevent sustained flue gas condensation. This is ofutmost important when a conventional boiler is used asthe heat source for a snow-melting system.

The system must use a control that measures the inlettemperature to the boiler and reduces the rate of heattransfer through the mixing device supplying to thesnowmelt system, when necessary, to preventsustained flue gas condensation. The mixing device

Figure 11-7

125

can be a 2-way, 3-way, or 4-way mixing valve orvariable speed injection pump as discussed in section3 and shown in figure 11-8.

Condensing boilers are well suited to the low operatingtemperatures of hydronic snow melting systems. Inmost cases there is no need to install a mixing devicebetween a condensing boiler and the snow melt distri-bution system. If the condensing boiler is operatedwith the same antifreeze solution as the snow meltcircuits, there is no need to install a heat exchanger.This minimizes the operating temperature of acondensing boiler and increases its efficiency.

Idling Pavement Surfaces

When the melting system starts from a cold temper-ature, it may take considerable time for the surface toreach melting temperature. To decrease this lag time,some snow melt controls can maintain the pavement at

an “idling” temperature just above or below freezing.

If the pavement temperature is idled just abovefreezing, it will generally be free of frost and “blackice”, and be an important advantage in terms of safety.Idling the pavement just below freezing reducesstandby heat loss, but still allows for rapid warm-up tomelting temperature. Most controls let the installeradjust the pavement idling temperature.

Control systems with idling capability typically initiatethe idling mode when the outside air temperaturedrops within a few degrees of freezing (35 to 40degrees F.). Such air temperatures represent the possi-bility of frozen precipitation. Idling the system abovethese air temperatures is largely a waste of fuel.

To idle the pavement, the controller must sensepavement temperature. Typically, a small thermistorsensor is located within a “well” in the slab. This wellis usually made of capped copper tubing that’s cast


Figure 11-8


126

into the pavement. The position of the slab temper-ature sensor is crucial to the proper performance of thecontrol system. The slab sensor is typically located 1”below the top of the pavement, and halfway betweenadjacent tube circuits. The open end of the well shouldlead to an accessible location so the sensor can bereplaced if it ever fails. Be sure to follow the controlmanufacturers’ recommendations regarding instal-lation of the pavement temperature sensor.

Manual Melting Control

Systems can be designed with manually operated startand stop controls. Typically the system beginssupplying heat to cold pavement when a switch ismoved to the “on” position. Heat flows to thepavement as long as the switch remains on.

This approach is fine, provided someone pays closeattention to the status of the snow on the pavement,and turns the system off as soon as melting iscompleted. If the attending person forgets the systemis operating, it could run indefinitely (or until it runsout of fuel). The cost of unnecessary operation can behigh, especially on larger systems. This possibility isthe single biggest argument against a manual start /manual stop control system.

The next logical refinement would be a control systemwith manual start and automatic shut off. The systemis shut off after a set time has elapsed. The time isselected by the person turning on the system based onthe amount of snow and previous experience with thesystem. Overriding conditions such as very cold airtemperatures, or sustained air temperatures abovefreezing, may also be used to terminate operation. Thegoal is to turn the system off as soon as melting iscomplete and the pavement is in the process of drying.The latter is important to prevent the formation ofdangerous “black ice.” Some manual start/automaticoff snowmelt controllers also allow the pavement to bemaintained at a set idling temperature.

Automatic Melting Control

More sophisticated snow melting controls are availablethat automatically detect frozen precipitation on theslab surface and initiate melting operation. They alsoterminate heat input when melting is complete. Mostcan also be configured to idle the pavement at aspecific temperature when desired.

Fully automatic snow melting controls require a snowdetection sensor. Some sensors are mounted directlyinto the top surface of the pavement and can detectwhen frozen precipitation is present, as well asmeasure pavement temperature. Other types of sensorsare mounted above the pavement. They provide an

electrical contact closure whenever precipitation isoccurring AND the outside air temperature is below agiven temperature.

Both types of sensors have a small heated cell at thetop of their housing. Precipitation is detected by theelectrical conductivity of the water on this cell. This, incombination with an air temperature just abovefreezing, provides the start-up criteria for the system.

Control systems that monitor pavement temperaturetend to reduce fuel usage by allowing the system tomaintain the pavement surface just a few degreesabove freezing. The cooler the pavement surface, thelower the heat losses.

Many snow melting controls can also prevent orterminate melting if the outside air temperature risesabove a preset value. In non-critical applications (class1 systems), melting can also be prevented or termi-nated during very cold weather when heat loss wouldbe excessive.

11-6 Circuit Design Information

Selecting the proper tube size, spacing and flow rate isan important part of system design. The section givestechnical guidelines and formulas that can be used toevaluate the trade-offs and help optimize the system.

Flow requirements

The flow rate required for a snow melting circuit todeliver a given amount of heat to the pavement can bedetermined using formula 11-1.

where:

f = required flow rate (gpm)

∆T = temperature drop on the loop(degF)

q = rate of heat output required (Btu/hr)

k = a constant based on the concentration of antifreeze used (see chart below)

For example: the flow rate required to deliver 22,000Btu/hr using a 40% solution of propylene glycol in acircuit operating with a 20 degree F. temperature drop is:

f =q

k x ∆T

Formula 11-1

100% water 30% Propyleneglycol

40% Propyleneglycol

50% Propyleneglycol

k=500 K=477 K=465 K=449

127

The rate of heat delivery required for many snowmelting applications is considerably higher than thatrequired for a typical floor heating system. To delivermore heat without excessive temperature drop, theflow rate in the embedded circuits must be increased.The use of glycol-based antifreeze solution (instead of100% water) reduces the heat carrying ability of theheat transfer fluid, and further increases the flowrequirement.

For example: the flow rate in a 250 foot long floorheating circuit, with tubing spaced 12" apart, deliv-ering 25 Btu/hr/sqft with a 20 degree F. drop in watertemperature is:

This flow is easily handled by a 3/8" or 1/2" tube.

However, the required flow rate in a 250 foot longcircuit using tubing spaced 12" apart, delivering 150Btu/hr/sqft with a temperature drop of 20 degrees F.,and using a 50% solution of propylene glycol is:

This flow rate is well beyond proper range of appli-cation for a 1/2" tube.

The common solution to the high flow requirement ofsnow melting systems is to use larger diameter tubing.5/8” Kitec pipe is commonly used in snow meltingapplications, while 3/4" diameter Kitec pipe issometimes used in larger systems.

In some locations, such as steps, the bending limita-tions of 5/8” and 3/4" Kitec pipe does not allow it tobe used. In these situations, use multiple shortercircuits of 1/2" pipe.

The following table gives suggested maximum circuitlengths for various sizes of Kitec pipe used in snowmelting applications. These lengths assume a 50%propylene glycol solution is carried by the tubing, andthat the allowable head loss is equivalent to that of a300 foot long circuit of 1/2" Kitec pipe used in a

typical floor heating application.

Note the allowable length of 1/2" tubing circuit isapproximately 50% that of 3/4" tubing. Likewise, theallowable length of a 5/8" Kitec tubing circuit isapproximately 65% that of 3/4" tubing.

Circuit Head Loss

The head loss of the snow melting circuits along withthe system flow requirements will determine the size ofthe system’s circulator(s). It’s important to select tubesizes and limit circuit lengths to prevent excessivehead loss in snow melting circuits.

Formula 11-2 can be used to estimate the head lossand resulting pressure drop in Kitec tubing carrying a50% solution of propylene glycol and water at a meantemperature of 100 degrees F. This temperature wasselected as representative of average conditions is aclass 1 (residential) system. The head loss is about12% higher than predicted by the formula when themean fluid is at 80 degrees F., and about 15% lowerwhen the fluid temperature is 140 degrees F.

where:

Hloss = head loss (feet of head)

c = a constant based on tube size (see table below)

L = circuit length (feet)

f = flow rate (US gpm)

1.75 = an exponent of the flow rate


f= = 0.63 gpmq

500 x ∆T= 250 x 25

500 x 20

f= = 4.2 gpmq

450 x ∆T= 250 x 150

449 x 20

1/2" Kitec

180 ft.

5/8" Kitec

250 ft.

3/4" Kitec

400 ft.

1" Kitec

560 ft.

maximum

circuit length

Hloss = c x L x f1.75

1/2" Kitec 5/8" Kitec 3/4" Kitec 1" Kitec

0.062 0.0154 0.00526 0.00189c value

f = 22000465 x 20

= 2.36 gpm

Formula 11-2


128

Circuit Temperature Drop

Most snow melting systems are designed with circuittemperature drops of 20 to 30 degrees F. under steadystate operation. However, during start-up of a coldpavement, the temperature drop can easily be 3 to 5times greater than this. This is why it’s so important toprotect a conventional boiler as discussed in theprevious section. As the slab gradually warms up, thetemperature drop decreases towards its nominal designvalue.

Temperature drops in excess of 30 degrees F. canresult in uneven melting patterns on pavementsurfaces. One novel approach to correcting thissituation is to periodically reverse the flow through thetubing circuits. A motorized 4-way mixing valve thatcycles from one end of its travel range to another basedon signals from a time delay relay is one way to do this.This concept allows more even heat distribution to the

pavement, and arguably could allow the system to usehigher steady state temperature drops. The largertemperature drops would reduce flow rates andrequired pumping power. The concept is shown infigure 11-9.

Estimating Heat Output

The exact heat output of a heated exterior pavementdepends on many simultaneous conditions such as airtemperature, wind speed, relative humidity, snowcoverage, rate of snow fall, pavement drainage charac-teristic, tube diameter, tube spacing, R-value ofunderside insulation, soil temperature and thermalproperties of the paving. Many of these conditionschange from one melting cycle to the next. Some ofthese parameters may not be known or readilyobtainable by the designer. Thus, it is very difficult todevelop a highly precise engineering model of a given

Figure 11-9

129


snow melting installation.

Formula 11-3 is an empirically derived relationshipthat can be used to approximate the heat output of asnowmelt slab using tubing spaced 12 inches apart,and covered with snow in the process of melting.

where:

Q = heat output (Btu/hr/sq. ft.)

MFT = mean fluid temperature in the circuit (degree F.)

For example: assume a tube circuit installed at 12 inchspacing is supplied with 120 degree F. fluid andoperates with a 20 degree F. temperature drop. Themean fluid temperature in the circuit is 110 degrees F.When the slab is covered with a film of water (from themelting snow), its rate of heat output is approximately:

Tube Spacing Factors

Figure 11-10 can be used to estimate the relative gainin heat output when tubes are spaced closer than 12inches apart. Simply multiply the slab’s heat outputassuming 12 inch tube spacing by the multiplier toestimate its heat output, using the same mean fluidtemperature, at closer tube spacing.

For example: if the pavement’s heat output usingtubing spaced 12 inches apart averages 154 Btu/hr/sq.ft., its estimated average heat output using 6 inch tubespacing, and the same mean fluid temperature is 154x 1.34 = 206 Btu/hr/sq. ft.

The following tube spacings are suggested as a generalguideline based on the system’s class. Obviously closertube spacing allow higher rates of heat delivery, albeitat a higher cost. Tube spaced more than 12” apart canlead to excessively uneven melting patterns, and is notrecommended.

Class 1 systems: 9-12 inches

Class 2 systems: 6-9 inches

Class 3 systems: 6 inches

IPEX RadiantTM design software can be used for furtherstudying the performance trade-offs of various tubespacing and fluid supply temperatures.

Figure 11-10

Q = 2 x (MFT - 33)

Q = 2 x (110 - 33) = 154 Btu/hr/sq.ft.

Formula 11-3

SECTION

12

IPEX RADIANTTM DESIGN SOFTWARE

The heating system is an integral part of building design and requires a specific and detailed design process.Heating engineers must analyze building location, function, occupancy and control requirements in order toselect and design the proper system and specify the appropriate components.

IPEX offers the state-of-the-art IPEX RadiantTM Design software program to assist designers in calculating anumber of the key design features of hydronic radiant heating systems.

IPEX RadiantTM greatly assists designers by performing the following tasks:

• Building heat loss calculations

• Floor output sizing to compensate for heat loss

• Floor piping details and specifications

• Control Panel and Manifold Selection

• Supply and Return Piping Design

• Temperature Control Selection Suited to the Project

• Project Material List and Report Generation

Project calculations are summarized in reports of varying details depending on your needs. Summary reportsprovide overall project design information while detailed reports present every aspect of your calculations.

IPEX Radiant comes complete with a WarmRite Floor component data base and prices. It lets you add non IPEXcomponents to your own data base of heating items regularly specified and it creates customer and project databases to assist in managing on-going designs and for future follow-up.

All of these features are compiled inside an interactive, user friendly software that gives designers the flexibilityto create and specify the best possible hydronic radiant heating system.

131


132

IPEX RadiantTM Design Software System Requirements

The program is offered on CD-ROM and must be loaded onto the hard drive of your computer. Minimum operatingsystem requirements are as follows:

Processor Pentium 133 or greaterHard Disk Space 50 MBRAM 32 MB minimum; 64 MB or greater recommendedVideo Adapter VGAOperating System Windows 95, Windows 98, Window NT4 (SP5) or Windows 2000

Insert the disk and loading starts automatically. If the Auto Run does not start choose Start / Run, type D:SETUPthen choose OK. The setup wizard will install the software onto your hard drive. Follow the screen prompts duringthis process.

When the installation is finished an icon will appear on your desktop, giving you access to IPEX Radiant at theclick of your mouse.

The IPEX RadiantTM Design Software is supported with a Help Wizard and full program tutorial.

To obtain your personal copy of the IPEX RadiantTM Design Software, please copy, complete and fax through therequired form on the following page.

SECTION 12 IPEX RADIANT DESIGN SOFTWARE

REQUEST FORM IPEX RADIANTTM DESIGN SOFTWARE AND/OR MANUAL OF MODERN HYDRONICS

Fax this completed form to 905-403-1124 to request your copy of the IPEX RadiantTM DesignSoftware and/or IPEX Manual of Modern Hydronics.

❏ Manual of ModernHydronics

❏ IPEX RadiantTM

Design Software

Name Title

Company Dept.

Address

City Province/State

Postal Code/Zip Phone

Fax E-mail

❏ Indicate if registrant is an Authorized WarmRite installer.

Company classification

❏ Architect/Designer ❏ Contractor ❏ Inspector

❏ Distributor ❏ Engineer ❏ Government

❏ Home Builder ❏ OEM - Products manufactured: ________________________________________

❏ Other _______________________________

SIC or industry sector:________________________________________

or copyBusiness Card

133

APPENDIX A

A1

HYDRONIC SCHEMATIC SYMBOLS

M

T

P

M

D

T

M

back flow preventer

swing check valve

flow check valve

spring loaded check valve

isolating valve

gate valve

globe valve

thermostatic valve

motorized valve

floating air vent

air separator

3 way mixing valve

diverting 3 way valve

thermostatic 3 way valve

motorized 3 way valve

4 way mixing valve

motorized 4 way valve

pressure gauge

APPENDIX A

A2


pressure reducing valve

pressure balancing bypass valve

pressure relief valve

drain valve

manual air vent

T

T/P

temperature gauge

thermo-pressure gauge

circulator

circulator withisolating flanges

expansion tank

APPENDIX A

A3


B

supply

return

P

WH

hot out

cold in

indirectWH

hot out

cold in

m

heat exchanger

base board

boiler

water heater

indirect waterheater

radiator

fan coil

radiant floor piping

manifold set

APPENDIX A

A4


supply manifold

return manifold balancing, flow indicator

manifold with balancing valves

plain manifold

manifold with actuator valves

manifold with isolating valves

APPENDIX A

A5

ELECTRICAL SYMBOLS

MIXINGCONTROL

thermostat

valve actuator (powerhead)

valve actuator (powerhead) with end switch

controller

combination snow/ice sensor

T

sensor

electrical heating element

transformer

single switch

temperature sensitiveswitch

APPENDIX A

A6

CONTROL PANEL SCHEMATIC SYMBOLS

injectionmixing controlpanel

recirculatingzone controlpanel

recirculatingzone controlpanel withexpansion tank

control panelwith heatexchanger

floor warmingcontrol panel

multi zonemanifoldstation

manifoldstation withcirculator

manifoldstation

snowmelt /industrialcontrol panel

injectionmixingsecondarycontrol panel

isolationmodule

APPENDIX B

B1

HEAD LOSS CALCULATIONS FOR XPA PIPE AND PEX TUBING

The following Appendix provides head loss information for XPA pipe and PEX tubing over a range of flowrates and liquid temperatures. Tables have been developed for 100% water as well as for a range ofglycol/water mixtures typically used in hydronic systems. For operating conditions not covered by thefollowing tables contact IPEX for further information.

IPEX follows ASHRAE principles for head loss calculation. In particular, the Friction Factor formula usedis a function of the Reynold’s Number - see below.

Diameter Flowrate Density Viscosity Reynolds Friction Loss / 100ft Velocity Flowrate Loss /100m Head Loss Velocityinch GPM kg/m3 106 Pa s Number Factor PSI ft/s L / min kPa m m / s

0.346 0.1 1004 1200 764.7 0.0837 0.23 0.34 0.39 5.17 0.00 0.10

0.346 0.2 1004 1200 1529.5 0.0418 0.46 0.68 0.78 10.3 0.00 0.21

0.346 0.3 1004 1200 2294.2 0.0279 0.69 1.02 1.17 15.5 0.00 0.31

0.346 0.4 1004 1200 3059.0 0.0425 1.86 1.36 1.56 42.0 0.01 0.42

0.346 0.5 1004 1200 3823.7 0.0402 2.74 1.71 1.95 62.1 0.02 0.52

0.346 0.6 1004 1200 4588.4 0.0384 3.78 2.05 2.33 85.4 0.03 0.62

0.346 0.7 1004 1200 5353.2 0.0369 4.94 2.39 2.72 112 0.03 0.73

0.346 0.8 1004 1200 6117.9 0.0357 6.25 2.73 3.11 141 0.04 0.83

0.346 0.9 1004 1200 6882.7 0.0347 7.68 3.07 3.50 174 0.05 0.94

0.346 1.0 1004 1200 7647.4 0.0338 9.23 3.41 3.89 209 0.06 1.04

0.346 1.1 1004 1200 8412.2 0.0330 10.9 3.75 4.28 247 0.08 1.14

0.346 1.2 1004 1200 9176.9 0.0323 12.7 4.09 4.67 287 0.09 1.25

0.346 1.3 1004 1200 9941.6 0.0281 13.0 4.44 5.06 294 0.09 1.35

0.346 1.4 1004 1200 10706.4 0.0277 14.8 4.78 5.45 336 0.10 1.46

0.346 1.5 1004 1200 11471.1 0.0273 16.8 5.12 5.84 380 0.12 1.56

0.346 1.6 1004 1200 12235.9 0.0269 18.8 5.46 6.22 426 0.13 1.66

0.346 1.7 1004 1200 13000.6 0.0266 21.0 5.80 6.61 475 0.15 1.77

0.346 1.8 1004 1200 13765.3 0.0263 23.3 6.14 7.00 526 0.16 1.87

0.346 1.9 1004 1200 14530.1 0.0260 25.6 6.48 7.39 580 0.18 1.98

0.346 2.0 1004 1200 15294.8 0.0257 28.1 6.82 7.78 636 0.20 2.08

3/8" XPA Pipe / 10% Glycol / 80 Deg F (27 Deg C)

Reynolds #

Re# = v d D / u

v = velocityd = inside diameterD = densityu = viscosity

head loss (m)

H = f (L/D) (v^2 / 2g)

v = velocityL = lengthD = diameterf = friction factorg = 9.81

velocity (ft/sec)

v = y / A

y = flowrateA = cross section area

friction factor

f = 64 / Re# if Re# < 3,000

f = 0.3164 / Re#^0.25 if 3,000 < Re# < 10,000

f = 0.0032 + 0.221 / Re#^0.237 if Re# > 10,000

APPENDIX B

B2

GPM PSI ft/s L / min kPa m / s0.1 0.16 0.34 0.39 3.73 0.100.2 0.33 0.68 0.78 7.45 0.210.3 1.03 1.02 1.17 23.3 0.310.4 1.70 1.36 1.56 38.5 0.420.5 2.51 1.71 1.95 56.9 0.520.6 3.46 2.05 2.33 78.3 0.620.7 4.53 2.39 2.72 102 0.730.8 5.72 2.73 3.11 129 0.830.9 7.03 3.07 3.50 159 0.941.0 7.54 3.41 3.89 171 1.041.1 8.94 3.75 4.28 202 1.141.2 10.5 4.09 4.67 236 1.251.3 12.1 4.44 5.06 273 1.351.4 13.8 4.78 5.45 312 1.461.5 15.6 5.12 5.84 353 1.561.6 17.5 5.46 6.22 396 1.661.7 19.5 5.80 6.61 441 1.771.8 21.6 6.14 7.00 489 1.871.9 23.8 6.48 7.39 539 1.982.0 26.1 6.82 7.78 591 2.08

3/8" XPA Pipe / 100% Water / 80 Deg F (27 Deg C)

Flowrate Loss per 100ft Velocity Flowrate Loss per 100m Velocity

HEAD LOSS - 3/8" XPA PIPE100% Water

GPM PSI ft/s L / min kPa m / s0.1 0.09 0.34 0.39 2.10 0.100.2 0.43 0.68 0.78 9.81 0.210.3 0.88 1.02 1.17 20.0 0.310.4 1.46 1.36 1.56 33.0 0.420.5 2.16 1.71 1.95 48.8 0.520.6 2.65 2.05 2.33 59.9 0.620.7 3.49 2.39 2.72 79.0 0.730.8 4.44 2.73 3.11 100 0.830.9 5.48 3.07 3.50 124 0.941.0 6.62 3.41 3.89 150 1.041.1 7.85 3.75 4.28 178 1.141.2 9.18 4.09 4.67 208 1.251.3 10.6 4.44 5.06 240 1.351.4 12.1 4.78 5.45 274 1.461.5 13.7 5.12 5.84 310 1.561.6 15.4 5.46 6.22 348 1.661.7 17.2 5.80 6.61 388 1.771.8 19.0 6.14 7.00 430 1.871.9 21.0 6.48 7.39 474 1.982.0 23.0 6.82 7.78 520 2.08





Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s0.1 0.07 0.34 0.39 1.49 0.100.2 0.39 0.68 0.78 8.92 0.210.3 0.80 1.02 1.17 18.1 0.310.4 1.18 1.36 1.56 26.7 0.420.5 1.76 1.71 1.95 39.8 0.520.6 2.44 2.05 2.33 55.2 0.620.7 3.22 2.39 2.72 72.8 0.730.8 4.09 2.73 3.11 92.5 0.830.9 5.05 3.07 3.50 114 0.941.0 6.10 3.41 3.89 138 1.041.1 7.24 3.75 4.28 164 1.141.2 8.47 4.09 4.67 192 1.251.3 9.78 4.44 5.06 221 1.351.4 11.2 4.78 5.45 253 1.461.5 12.7 5.12 5.84 286 1.561.6 14.2 5.46 6.22 321 1.661.7 15.8 5.80 6.61 358 1.771.8 17.6 6.14 7.00 397 1.871.9 19.4 6.48 7.39 438 1.982.0 21.2 6.82 7.78 480 2.08








APPENDIX B

B3

GPM PSI ft/s L / min kPa m / s0.1 0.04 0.16 0.39 0.85 0.050.2 0.08 0.33 0.78 1.71 0.100.3 0.11 0.49 1.17 2.56 0.150.4 0.30 0.65 1.56 6.70 0.200.5 0.44 0.82 1.95 9.90 0.250.6 0.60 0.98 2.33 13.6 0.300.7 0.79 1.14 2.72 17.8 0.350.8 1.00 1.31 3.11 22.5 0.400.9 1.22 1.47 3.50 27.7 0.451.0 1.47 1.63 3.89 33.3 0.501.1 1.74 1.80 4.28 39.3 0.551.2 2.02 1.96 4.67 45.8 0.601.3 2.33 2.12 5.06 52.7 0.651.4 2.36 2.29 5.45 53.4 0.701.5 2.67 2.45 5.84 60.4 0.751.6 3.00 2.61 6.22 67.8 0.801.7 3.34 2.78 6.61 75.6 0.851.8 3.70 2.94 7.00 83.8 0.901.9 4.08 3.10 7.39 92.3 0.95

2.0 4.47 3.27 7.78 101 1.00




GPM PSI ft/s L / min kPa m / s0.1 0.02 0.16 0.39 0.48 0.050.2 0.04 0.33 0.78 0.96 0.100.3 0.15 0.49 1.17 3.47 0.150.4 0.25 0.65 1.56 5.74 0.200.5 0.38 0.82 1.95 8.49 0.250.6 0.52 0.98 2.33 11.7 0.300.7 0.68 1.14 2.72 15.3 0.350.8 0.76 1.31 3.11 17.2 0.400.9 0.94 1.47 3.50 21.2 0.451.0 1.13 1.63 3.89 25.6 0.501.1 1.34 1.80 4.28 30.4 0.551.2 1.57 1.96 4.67 35.6 0.601.3 1.81 2.12 5.06 41.0 0.651.4 2.07 2.29 5.45 46.9 0.701.5 2.35 2.45 5.84 53.0 0.751.6 2.63 2.61 6.22 59.6 0.801.7 2.94 2.78 6.61 66.4 0.851.8 3.25 2.94 7.00 73.6 0.901.9 3.58 3.10 7.39 81.1 0.952.0 3.93 3.27 7.78 88.9 1.00





Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s0.1 0.02 0.16 0.39 0.34 0.050.2 0.07 0.33 0.78 1.55 0.100.3 0.14 0.49 1.17 3.15 0.150.4 0.23 0.65 1.56 5.22 0.200.5 0.34 0.82 1.95 7.71 0.250.6 0.42 0.98 2.33 9.46 0.300.7 0.55 1.14 2.72 12.5 0.350.8 0.70 1.31 3.11 15.8 0.400.9 0.86 1.47 3.50 19.6 0.451.0 1.04 1.63 3.89 23.6 0.501.1 1.24 1.80 4.28 28.0 0.551.2 1.45 1.96 4.67 32.8 0.601.3 1.67 2.12 5.06 37.8 0.651.4 1.91 2.29 5.45 43.2 0.701.5 2.16 2.45 5.84 48.9 0.751.6 2.43 2.61 6.22 54.9 0.801.7 2.71 2.78 6.61 61.3 0.851.8 3.00 2.94 7.00 67.9 0.901.9 3.31 3.10 7.39 74.8 0.952.0 3.63 3.27 7.78 82.0 1.00








APPENDIX B

B4


















APPENDIX B

B5


















APPENDIX B

B6

GPM PSI ft/s L / min kPa m / s1.0 0.15 0.63 3.89 3.45 0.192.0 0.51 1.26 7.78 11.6 0.383.0 0.94 1.89 11.7 21.2 0.584.0 1.57 2.52 15.6 35.5 0.775.0 2.35 3.14 19.5 53.1 0.966.0 3.25 3.77 23.3 73.6 1.157.0 4.29 4.40 27.2 97.1 1.348.0 5.46 5.03 31.1 123 1.539.0 6.74 5.66 35.0 153 1.73

10.0 8.15 6.29 38.9 184 1.9211.0 9.68 6.92 42.8 219 2.1112.0 11.3 7.55 46.7 256 2.3013.0 13.1 8.17 50.6 296 2.4914.0 14.9 8.80 54.5 338 2.6815.0 16.9 9.43 58.4 383 2.8816.0 19.0 10.1 62.2 430 3.0717.0 21.2 10.7 66.1 480 3.2618.0 23.5 11.3 70.0 532 3.4519.0 25.9 11.9 73.9 586 3.6420.0 28.4 12.6 77.8 643 3.83



HEAD LOSS - 3/4" XPA SUPPLY PIPE100% Water


10.0 7.20 6.29 38.9 163 1.9211.0 8.55 6.92 42.8 193 2.1112.0 10.0 7.55 46.7 226 2.3013.0 11.6 8.17 50.6 261 2.4914.0 13.2 8.80 54.5 299 2.6815.0 15.0 9.43 58.4 339 2.8816.0 16.8 10.1 62.2 380 3.0717.0 18.8 10.7 66.1 424 3.2618.0 20.8 11.3 70.0 471 3.4519.0 22.9 11.9 73.9 519 3.6420.0 25.2 12.6 77.8 570 3.83




10.0 7.43 6.29 38.9 168 1.9211.0 8.82 6.92 42.8 199 2.1112.0 10.3 7.55 46.7 233 2.3013.0 11.9 8.17 50.6 270 2.4914.0 13.6 8.80 54.5 308 2.6815.0 15.4 9.43 58.4 349 2.8816.0 17.3 10.1 62.2 392 3.0717.0 19.4 10.7 66.1 438 3.2618.0 21.5 11.3 70.0 485 3.4519.0 23.7 11.9 73.9 535 3.6420.0 26.0 12.6 77.8 587 3.83


Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s1.0 0.12 0.63 3.89 2.69 0.192.0 0.37 1.26 7.78 8.31 0.383.0 0.76 1.89 11.7 17.2 0.584.0 1.28 2.52 15.6 28.9 0.775.0 1.91 3.14 19.5 43.1 0.966.0 2.65 3.77 23.3 59.9 1.157.0 3.50 4.40 27.2 79.1 1.348.0 4.45 5.03 31.1 101 1.539.0 5.51 5.66 35.0 125 1.73

10.0 6.66 6.29 38.9 151 1.9211.0 7.91 6.92 42.8 179 2.1112.0 9.26 7.55 46.7 209 2.3013.0 10.7 8.17 50.6 242 2.4914.0 12.2 8.80 54.5 277 2.6815.0 13.9 9.43 58.4 314 2.8816.0 15.6 10.1 62.2 353 3.0717.0 17.4 10.7 66.1 393 3.2618.0 19.3 11.3 70.0 436 3.4519.0 21.3 11.9 73.9 481 3.6420.0 23.4 12.6 77.8 528 3.83




10.0 7.76 6.29 38.9 175 1.9211.0 9.21 6.92 42.8 208 2.1112.0 10.8 7.55 46.7 244 2.3013.0 12.4 8.17 50.6 282 2.4914.0 14.2 8.80 54.5 322 2.6815.0 16.1 9.43 58.4 365 2.8816.0 18.1 10.1 62.2 410 3.0717.0 20.2 10.7 66.1 457 3.2618.0 22.4 11.3 70.0 507 3.4519.0 24.7 11.9 73.9 559 3.6420.0 27.1 12.6 77.8 613 3.83


Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s1.0 0.12 0.63 3.89 2.80 0.192.0 0.38 1.26 7.78 8.61 0.383.0 0.79 1.89 11.7 17.8 0.584.0 1.32 2.52 15.6 29.9 0.775.0 1.97 3.14 19.5 44.7 0.966.0 2.74 3.77 23.3 62.0 1.157.0 3.62 4.40 27.2 81.9 1.348.0 4.61 5.03 31.1 104 1.539.0 5.70 5.66 35.0 129 1.73

10.0 6.89 6.29 38.9 156 1.9211.0 8.19 6.92 42.8 185 2.1112.0 9.58 7.55 46.7 217 2.3013.0 11.1 8.17 50.6 250 2.4914.0 12.7 8.80 54.5 286 2.6815.0 14.3 9.43 58.4 324 2.8816.0 16.1 10.1 62.2 365 3.0717.0 18.0 10.7 66.1 407 3.2618.0 19.9 11.3 70.0 451 3.4519.0 22.0 11.9 73.9 498 3.6420.0 24.1 12.6 77.8 546 3.83



APPENDIX B

B7


1" XPA Pipe / 100% Water / 80 Deg F (27 Deg C)


HEAD LOSS - 1" XPA PIPE100% Water














APPENDIX B

B8

GPM PSI ft/s L / min kPa m / s1.0 0.05 0.38 3.89 1.07 0.122.0 0.16 0.77 7.78 3.58 0.233.0 0.29 1.15 11.7 6.49 0.354.0 0.48 1.53 15.6 10.9 0.475.0 0.72 1.92 19.5 16.2 0.586.0 0.99 2.30 23.3 22.5 0.707.0 1.31 2.68 27.2 29.7 0.828.0 1.67 3.07 31.1 37.7 0.949.0 2.06 3.45 35.0 46.6 1.05

10.0 2.49 3.84 38.9 56.3 1.1711.0 2.95 4.22 42.8 66.8 1.2912.0 3.46 4.60 46.7 78.2 1.4013.0 3.99 4.99 50.6 90.3 1.5214.0 4.56 5.37 54.5 103 1.6415.0 5.16 5.75 58.4 117 1.7516.0 5.80 6.14 62.2 131 1.8717.0 6.47 6.52 66.1 146 1.9918.0 7.17 6.90 70.0 162 2.1019.0 7.91 7.29 73.9 179 2.2220.0 8.67 7.67 77.8 196 2.34



HEAD LOSS - 1" XPA SUPPLY PIPE100% Water


10.0 2.20 3.84 38.9 49.7 1.1711.0 2.61 4.22 42.8 59.0 1.2912.0 3.05 4.60 46.7 69.0 1.4013.0 3.52 4.99 50.6 79.7 1.5214.0 4.03 5.37 54.5 91.1 1.6415.0 4.56 5.75 58.4 103 1.7516.0 5.13 6.14 62.2 116 1.8717.0 5.72 6.52 66.1 129 1.9918.0 6.34 6.90 70.0 143 2.1019.0 6.99 7.29 73.9 158 2.2220.0 7.67 7.67 77.8 174 2.34




10.0 2.27 3.84 38.9 51.3 1.1711.0 2.69 4.22 42.8 60.9 1.2912.0 3.15 4.60 46.7 71.2 1.4013.0 3.64 4.99 50.6 82.2 1.5214.0 4.16 5.37 54.5 94.0 1.6415.0 4.71 5.75 58.4 106 1.7516.0 5.29 6.14 62.2 120 1.8717.0 5.90 6.52 66.1 133 1.9918.0 6.54 6.90 70.0 148 2.1019.0 7.21 7.29 73.9 163 2.2220.0 7.91 7.67 77.8 179 2.34


Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s1.0 0.04 0.38 3.89 0.83 0.122.0 0.11 0.77 7.78 2.54 0.233.0 0.23 1.15 11.7 5.26 0.354.0 0.39 1.53 15.6 8.82 0.475.0 0.58 1.92 19.5 13.2 0.586.0 0.81 2.30 23.3 18.3 0.707.0 1.07 2.68 27.2 24.1 0.828.0 1.36 3.07 31.1 30.7 0.949.0 1.68 3.45 35.0 38.0 1.05

10.0 2.03 3.84 38.9 45.9 1.1711.0 2.41 4.22 42.8 54.6 1.2912.0 2.82 4.60 46.7 63.8 1.4013.0 3.26 4.99 50.6 73.8 1.5214.0 3.73 5.37 54.5 84.3 1.6415.0 4.22 5.75 58.4 95.5 1.7516.0 4.75 6.14 62.2 107 1.8717.0 5.30 6.52 66.1 120 1.9918.0 5.87 6.90 70.0 133 2.1019.0 6.48 7.29 73.9 147 2.2220.0 7.11 7.67 77.8 161 2.34




10.0 2.37 3.84 38.9 53.6 1.1711.0 2.81 4.22 42.8 63.6 1.2912.0 3.29 4.60 46.7 74.4 1.4013.0 3.80 4.99 50.6 85.9 1.5214.0 4.34 5.37 54.5 98.2 1.6415.0 4.92 5.75 58.4 111 1.7516.0 5.52 6.14 62.2 125 1.8717.0 6.16 6.52 66.1 139 1.9918.0 6.83 6.90 70.0 154 2.1019.0 7.53 7.29 73.9 170 2.2220.0 8.26 7.67 77.8 187 2.34



10.0 2.10 3.84 38.9 47.5 1.1711.0 2.50 4.22 42.8 56.5 1.2912.0 2.92 4.60 46.7 66.1 1.4013.0 3.37 4.99 50.6 76.3 1.5214.0 3.86 5.37 54.5 87.3 1.6415.0 4.37 5.75 58.4 98.8 1.7516.0 4.91 6.14 62.2 111 1.8717.0 5.48 6.52 66.1 124 1.9918.0 6.08 6.90 70.0 137 2.1019.0 6.70 7.29 73.9 152 2.2220.0 7.35 7.67 77.8 166 2.34



APPENDIX B

B9

GPM PSI ft/s L / min kPa m / s0.1 0.16 0.34 0.39 3.73 0.100.2 0.33 0.68 0.78 7.45 0.210.3 1.03 1.02 1.17 23.3 0.310.4 1.70 1.36 1.56 38.5 0.420.5 2.51 1.71 1.95 56.9 0.520.6 3.46 2.05 2.33 78.3 0.620.7 4.53 2.39 2.72 102 0.730.8 5.72 2.73 3.11 129 0.830.9 7.03 3.07 3.50 159 0.941.0 7.54 3.41 3.89 171 1.041.1 8.94 3.75 4.28 202 1.141.2 10.5 4.09 4.67 236 1.251.3 12.1 4.44 5.06 273 1.351.4 13.8 4.78 5.45 312 1.461.5 15.6 5.12 5.84 353 1.561.6 17.5 5.46 6.22 396 1.661.7 19.5 5.80 6.61 441 1.771.8 21.6 6.14 7.00 489 1.871.9 23.8 6.48 7.39 539 1.982.0 26.1 6.82 7.78 591 2.08

3/8" PEX Tubing / 100% Water / 80 Deg F (27 Deg C)


HEAD LOSS - 3/8" PEX TUBING100% Water














APPENDIX B

B10

GPM PSI ft/s L / min kPa m / s0.1 0.04 0.17 0.39 0.97 0.050.2 0.09 0.35 0.78 1.93 0.110.3 0.13 0.52 1.17 2.90 0.160.4 0.34 0.69 1.56 7.74 0.210.5 0.51 0.87 1.95 11.4 0.260.6 0.70 1.04 2.33 15.7 0.320.7 0.91 1.22 2.72 20.6 0.370.8 1.15 1.39 3.11 26.0 0.420.9 1.41 1.56 3.50 32.0 0.481.0 1.70 1.74 3.89 38.5 0.531.1 2.01 1.91 4.28 45.5 0.581.2 2.34 2.08 4.67 52.9 0.641.3 2.69 2.26 5.06 60.9 0.691.4 2.80 2.43 5.45 63.3 0.741.5 3.16 2.60 5.84 71.6 0.791.6 3.55 2.78 6.22 80.4 0.851.7 3.96 2.95 6.61 89.6 0.901.8 4.39 3.13 7.00 99.2 0.951.9 4.83 3.30 7.39 109 1.012.0 5.30 3.47 7.78 120 1.06




GPM PSI ft/s L / min kPa m / s0.1 0.02 0.17 0.39 0.54 0.050.2 0.05 0.35 0.78 1.09 0.110.3 0.18 0.52 1.17 4.01 0.160.4 0.29 0.69 1.56 6.64 0.210.5 0.43 0.87 1.95 9.81 0.260.6 0.60 1.04 2.33 13.5 0.320.7 0.78 1.22 2.72 17.7 0.370.8 0.90 1.39 3.11 20.4 0.420.9 1.11 1.56 3.50 25.2 0.481.0 1.34 1.74 3.89 30.4 0.531.1 1.59 1.91 4.28 36.0 0.581.2 1.86 2.08 4.67 42.1 0.641.3 2.15 2.26 5.06 48.6 0.691.4 2.45 2.43 5.45 55.5 0.741.5 2.78 2.60 5.84 62.8 0.791.6 3.12 2.78 6.22 70.5 0.851.7 3.48 2.95 6.61 78.7 0.901.8 3.85 3.13 7.00 87.1 0.951.9 4.25 3.30 7.39 96.0 1.012.0 4.65 3.47 7.78 105 1.06








GPM PSI ft/s L / min kPa m / s0.1 0.03 0.17 0.39 0.76 0.050.2 0.07 0.35 0.78 1.53 0.110.3 0.10 0.52 1.17 2.29 0.160.4 0.32 0.69 1.56 7.28 0.210.5 0.48 0.87 1.95 10.8 0.260.6 0.65 1.04 2.33 14.8 0.320.7 0.86 1.22 2.72 19.4 0.370.8 1.08 1.39 3.11 24.5 0.420.9 1.33 1.56 3.50 30.1 0.481.0 1.60 1.74 3.89 36.2 0.531.1 1.72 1.91 4.28 39.0 0.581.2 2.01 2.08 4.67 45.6 0.641.3 2.33 2.26 5.06 52.6 0.691.4 2.66 2.43 5.45 60.1 0.741.5 3.00 2.60 5.84 68.0 0.791.6 3.37 2.78 6.22 76.3 0.851.7 3.76 2.95 6.61 85.1 0.901.8 4.17 3.13 7.00 94.2 0.951.9 4.59 3.30 7.39 104 1.012.0 5.03 3.47 7.78 114 1.06


Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s0.1 0.02 0.17 0.39 0.45 0.050.2 0.08 0.35 0.78 1.87 0.110.3 0.17 0.52 1.17 3.80 0.160.4 0.28 0.69 1.56 6.29 0.210.5 0.41 0.87 1.95 9.29 0.260.6 0.57 1.04 2.33 12.8 0.320.7 0.68 1.22 2.72 15.3 0.370.8 0.86 1.39 3.11 19.5 0.420.9 1.06 1.56 3.50 24.0 0.481.0 1.28 1.74 3.89 29.0 0.531.1 1.52 1.91 4.28 34.4 0.581.2 1.78 2.08 4.67 40.2 0.641.3 2.05 2.26 5.06 46.4 0.691.4 2.35 2.43 5.45 53.1 0.741.5 2.65 2.60 5.84 60.0 0.791.6 2.98 2.78 6.22 67.4 0.851.7 3.32 2.95 6.61 75.2 0.901.8 3.68 3.13 7.00 83.3 0.951.9 4.06 3.30 7.39 91.8 1.012.0 4.45 3.47 7.78 101 1.06



APPENDIX B

B11


















APPENDIX B

B12


















APPENDIX B

B13


1" PEX Tubing / 100% Water / 80 Deg F (27 Deg C)


HEAD LOSS - 1" PEX TUBING100% Water














APPENDIX B

B14

GPM PSI ft/s L / min kPa m / s1.0 0.10 0.53 3.89 2.33 0.162.0 0.35 1.07 7.78 7.85 0.333.0 0.63 1.60 11.7 14.3 0.494.0 1.06 2.13 15.6 24.0 0.655.0 1.58 2.67 19.5 35.8 0.816.0 2.19 3.20 23.3 49.6 0.987.0 2.89 3.73 27.2 65.5 1.148.0 3.68 4.27 31.1 83.2 1.309.0 4.55 4.80 35.0 103 1.46

10.0 5.50 5.34 38.9 124 1.6311.0 6.52 5.87 42.8 148 1.7912.0 7.63 6.40 46.7 173 1.9513.0 8.81 6.94 50.6 199 2.1114.0 10.1 7.47 54.5 228 2.2815.0 11.4 8.00 58.4 258 2.4416.0 12.8 8.54 62.2 290 2.6017.0 14.3 9.07 66.1 323 2.7718.0 15.8 9.60 70.0 358 2.9319.0 17.5 10.1 73.9 395 3.0920.0 19.2 10.7 77.8 433 3.25



HEAD LOSS - 1" PEX SUPPLY TUBING100% Water


10.0 4.85 5.34 38.9 110 1.6311.0 5.76 5.87 42.8 130 1.7912.0 6.74 6.40 46.7 152 1.9513.0 7.79 6.94 50.6 176 2.1114.0 8.90 7.47 54.5 201 2.2815.0 10.1 8.00 58.4 228 2.4416.0 11.3 8.54 62.2 256 2.6017.0 12.6 9.07 66.1 286 2.7718.0 14.0 9.60 70.0 317 2.9319.0 15.5 10.1 73.9 350 3.0920.0 17.0 10.7 77.8 384 3.25




10.0 5.00 5.34 38.9 113 1.6311.0 5.94 5.87 42.8 134 1.7912.0 6.95 6.40 46.7 157 1.9513.0 8.03 6.94 50.6 182 2.1114.0 9.18 7.47 54.5 208 2.2815.0 10.4 8.00 58.4 235 2.4416.0 11.7 8.54 62.2 264 2.6017.0 13.0 9.07 66.1 295 2.7718.0 14.5 9.60 70.0 327 2.9319.0 15.9 10.1 73.9 361 3.0920.0 17.5 10.7 77.8 396 3.25



10.0 4.49 5.34 38.9 102 1.6311.0 5.33 5.87 42.8 121 1.7912.0 6.24 6.40 46.7 141 1.9513.0 7.21 6.94 50.6 163 2.1114.0 8.24 7.47 54.5 186 2.2815.0 9.34 8.00 58.4 211 2.4416.0 10.5 8.54 62.2 237 2.6017.0 11.7 9.07 66.1 265 2.7718.0 13.0 9.60 70.0 294 2.9319.0 14.3 10.1 73.9 324 3.0920.0 15.7 10.7 77.8 356 3.25




10.0 5.23 5.34 38.90 118 1.6311.0 6.21 5.87 42.79 140 1.7912.0 7.26 6.40 46.68 164 1.9513.0 8.39 6.94 50.57 190 2.1114.0 9.59 7.47 54.46 217 2.2815.0 10.9 8.00 58.35 246 2.4416.0 12.2 8.54 62.24 276 2.6017.0 13.6 9.07 66.13 308 2.7718.0 15.1 9.60 70.02 341 2.9319.0 16.6 10.1 73.91 376 3.0920.0 18.3 10.7 77.80 413 3.25



10.0 4.64 5.34 38.9 105 1.6311.0 5.52 5.87 42.8 125 1.7912.0 6.45 6.40 46.7 146 1.9513.0 7.46 6.94 50.6 169 2.1114.0 8.53 7.47 54.5 193 2.2815.0 9.66 8.00 58.4 219 2.4416.0 10.9 8.54 62.2 246 2.6017.0 12.1 9.07 66.1 274 2.7718.0 13.4 9.60 70.0 304 2.9319.0 14.8 10.1 73.9 335 3.0920.0 16.3 10.7 77.8 368 3.25



APPENDIX B

B15

GPM PSI ft/s L / min kPa m / s0.1 0.11 0.16 0.39 2.40 0.050.2 0.21 0.33 0.78 4.80 0.100.3 0.32 0.49 1.17 7.20 0.150.4 0.42 0.65 1.56 9.60 0.200.5 0.53 0.82 1.95 12.0 0.250.6 0.64 0.98 2.33 14.4 0.300.7 0.74 1.14 2.72 16.8 0.350.8 0.85 1.31 3.11 19.2 0.400.9 0.96 1.47 3.50 21.6 0.451.0 1.06 1.63 3.89 24.0 0.501.1 1.29 1.80 4.28 26.4 0.551.2 2.29 1.96 4.67 60.4 0.601.3 3.07 2.12 5.06 69.5 0.651.4 3.50 2.29 5.45 79.1 0.701.5 3.95 2.45 5.84 89.3 0.751.6 4.42 2.61 6.22 100 0.801.7 4.91 2.78 6.61 111 0.851.8 5.43 2.94 7.00 123 0.901.9 5.97 3.10 7.39 135 0.952.0 6.53 3.27 7.78 148 1.00



HEAD LOSS - 1/2" XPA PIPE30% Glycol




GPM PSI ft/s L / min kPa m / s0.1 0.06 0.16 0.39 1.28 0.050.2 0.11 0.33 0.78 2.57 0.100.3 0.17 0.49 1.17 3.85 0.150.4 0.23 0.65 1.56 5.14 0.200.5 0.28 0.82 1.95 6.42 0.250.6 0.34 0.98 2.33 7.71 0.300.7 0.88 1.14 2.72 19.9 0.350.8 1.11 1.31 3.11 25.2 0.400.9 1.37 1.47 3.50 31.0 0.451.0 1.65 1.63 3.89 37.2 0.501.1 1.94 1.80 4.28 44.0 0.551.2 2.26 1.96 4.67 51.2 0.601.3 2.60 2.12 5.06 58.9 0.651.4 2.97 2.29 5.45 67.1 0.701.5 3.35 2.45 5.84 75.7 0.751.6 3.75 2.61 6.22 84.7 0.801.7 4.17 2.78 6.61 94.2 0.851.8 4.60 2.94 7.00 104 0.901.9 5.06 3.10 7.39 114 0.952.0 5.54 3.27 7.78 125 1.00





GPM PSI ft/s L / min kPa m / s0.1 0.08 0.16 0.39 1.71 0.050.2 0.15 0.33 0.78 3.42 0.100.3 0.23 0.49 1.17 5.13 0.150.4 0.30 0.65 1.56 6.84 0.200.5 0.38 0.82 1.95 8.55 0.250.6 0.45 0.98 2.33 10.3 0.300.7 0.53 1.14 2.72 12.0 0.350.8 0.60 1.31 3.11 13.7 0.400.9 1.48 1.47 3.50 33.4 0.451.0 1.78 1.63 3.89 40.2 0.501.1 2.10 1.80 4.28 47.5 0.551.2 2.44 1.96 4.67 55.3 0.601.3 2.81 2.12 5.06 63.6 0.651.4 3.20 2.29 5.45 72.4 0.701.5 3.61 2.45 5.84 81.7 0.751.6 4.04 2.61 6.22 91.4 0.801.7 4.49 2.78 6.61 102 0.851.8 4.97 2.94 7.00 112 0.901.9 5.46 3.10 7.39 123 0.952.0 5.97 3.27 7.78 135 1.00





APPENDIX B

B16















Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s0.1 0.06 0.16 0.39 1.33 0.050.2 0.12 0.33 0.78 2.67 0.100.3 0.18 0.49 1.17 4.00 0.150.4 0.24 0.65 1.56 5.34 0.200.5 0.29 0.82 1.95 6.67 0.250.6 0.35 0.98 2.33 8.00 0.300.7 0.89 1.14 2.72 20.0 0.350.8 1.12 1.31 3.11 25.3 0.400.9 1.37 1.47 3.50 31.1 0.451.0 1.65 1.63 3.89 37.4 0.501.1 1.95 1.80 4.28 44.2 0.551.2 2.27 1.96 4.67 51.4 0.601.3 2.62 2.12 5.06 59.2 0.651.4 2.98 2.29 5.45 67.4 0.701.5 3.36 2.45 5.84 76.0 0.751.6 3.76 2.61 6.22 85.1 0.801.7 4.18 2.78 6.61 94.6 0.851.8 4.62 2.94 7.00 105 0.901.9 5.08 3.10 7.39 115 0.952.0 5.56 3.27 7.78 126 1.00



APPENDIX B

B17


















APPENDIX B

B18


















APPENDIX B

B19


















APPENDIX B

B20


















APPENDIX B

B21

GPM PSI ft/s L / min kPa m / s0.1 0.12 0.17 0.39 2.71 0.050.2 0.24 0.35 0.78 5.42 0.110.3 0.36 0.52 1.17 8.14 0.160.4 0.48 0.69 1.56 10.8 0.210.5 0.60 0.87 1.95 13.6 0.260.6 0.72 1.04 2.33 16.3 0.320.7 0.84 1.22 2.72 19.0 0.370.8 0.96 1.39 3.11 21.7 0.420.9 1.08 1.56 3.50 24.4 0.481.0 1.20 1.74 3.89 27.1 0.531.1 2.65 1.91 4.28 60.0 0.581.2 3.09 2.08 4.67 69.8 0.641.3 3.55 2.26 5.06 80.3 0.691.4 4.04 2.43 5.45 91.4 0.741.5 4.56 2.60 5.84 103 0.791.6 5.11 2.78 6.22 116 0.851.7 5.68 2.95 6.61 128 0.901.8 6.28 3.13 7.00 142 0.951.9 6.90 3.30 7.39 156 1.012.0 7.55 3.47 7.78 171 1.06

1/2" PEX Tubing / 30% Glycol / 80 Deg F (27 Deg C)


HEAD LOSS - 1/2" PEX TUBING30% Glycol






Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s0.1 0.03 0.17 0.39 0.76 0.050.2 0.07 0.35 0.78 1.52 0.110.3 0.10 0.52 1.17 2.28 0.160.4 0.32 0.69 1.56 7.23 0.210.5 0.47 0.87 1.95 10.7 0.260.6 0.65 1.04 2.33 14.7 0.320.7 0.85 1.22 2.72 19.3 0.370.8 1.08 1.39 3.11 24.3 0.420.9 1.32 1.56 3.50 29.9 0.481.0 1.59 1.74 3.89 36.0 0.531.1 1.67 1.91 4.28 37.9 0.581.2 1.96 2.08 4.67 44.2 0.641.3 2.26 2.26 5.06 51.1 0.691.4 2.58 2.43 5.45 58.3 0.741.5 2.92 2.60 5.84 66.0 0.791.6 3.27 2.78 6.22 74.1 0.851.7 3.65 2.95 6.61 82.6 0.901.8 4.04 3.13 7.00 91.5 0.951.9 4.46 3.30 7.39 101 1.012.0 4.89 3.47 7.78 111 1.06





Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s0.1 0.04 0.17 0.39 0.92 0.050.2 0.08 0.35 0.78 1.83 0.110.3 0.12 0.52 1.17 2.75 0.160.4 0.34 0.69 1.56 7.63 0.210.5 0.50 0.87 1.95 11.3 0.260.6 0.69 1.04 2.33 15.5 0.320.7 0.90 1.22 2.72 20.3 0.370.8 1.14 1.39 3.11 25.7 0.420.9 1.39 1.56 3.50 31.6 0.481.0 1.68 1.74 3.89 37.9 0.531.1 1.98 1.91 4.28 44.8 0.581.2 2.31 2.08 4.67 52.2 0.641.3 2.36 2.26 5.06 53.5 0.691.4 2.70 2.43 5.45 61.1 0.741.5 3.05 2.60 5.84 69.1 0.791.6 3.43 2.78 6.22 77.6 0.851.7 3.82 2.95 6.61 86.5 0.901.8 4.23 3.13 7.00 95.8 0.951.9 4.67 3.30 7.39 106 1.012.0 5.11 3.47 7.78 116 1.06



APPENDIX B

B22










Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s0.1 0.05 0.17 0.39 1.21 0.050.2 0.11 0.35 0.78 2.41 0.110.3 0.16 0.52 1.17 3.62 0.160.4 0.21 0.69 1.56 4.82 0.210.5 0.53 0.87 1.95 12.1 0.260.6 0.73 1.04 2.33 16.6 0.320.7 0.96 1.22 2.72 21.7 0.370.8 1.21 1.39 3.11 27.5 0.420.9 1.49 1.56 3.50 33.8 0.481.0 1.79 1.74 3.89 40.6 0.531.1 2.12 1.91 4.28 48.0 0.581.2 2.47 2.08 4.67 55.8 0.641.3 2.84 2.26 5.06 64.2 0.691.4 3.23 2.43 5.45 73.1 0.741.5 3.65 2.60 5.84 82.5 0.791.6 4.08 2.78 6.22 92.4 0.851.7 4.04 2.95 6.61 91.4 0.901.8 4.48 3.13 7.00 101 0.951.9 4.93 3.30 7.39 112 1.012.0 5.41 3.47 7.78 122 1.06





Flowrate Loss per 100ft Velocity Flowrate Loss per 100m VelocityGPM PSI ft/s L / min kPa m / s0.1 0.07 0.17 0.39 1.51 0.050.2 0.13 0.35 0.78 3.01 0.110.3 0.20 0.52 1.17 4.52 0.160.4 0.27 0.69 1.56 6.03 0.210.5 0.33 0.87 1.95 7.53 0.260.6 0.40 1.04 2.33 9.04 0.320.7 1.02 1.22 2.72 23.1 0.370.8 1.29 1.39 3.11 29.2 0.420.9 1.59 1.56 3.50 35.9 0.481.0 1.91 1.74 3.89 43.2 0.531.1 2.26 1.91 4.28 51.0 0.581.2 2.63 2.08 4.67 59.4 0.641.3 3.02 2.26 5.06 68.4 0.691.4 3.44 2.43 5.45 77.8 0.741.5 3.88 2.60 5.84 87.8 0.791.6 4.35 2.78 6.22 98.3 0.851.7 4.83 2.95 6.61 109 0.901.8 5.34 3.13 7.00 121 0.951.9 5.87 3.30 7.39 133 1.012.0 6.42 3.47 7.78 145 1.06



APPENDIX B

B23


















APPENDIX B

B24


















APPENDIX B

B25


















APPENDIX B

B26


















ABOUT IPEXIPEX, a leading supplier of hydronic radiant heating solutions, offers an innovative and compre-hensive range of heating products throughout the North American marketplace. These productsform the WarmRite Floor® – IPEX Radiant System and include Kitec® XPA™ pipe, PEX tubing,pre-assembled control panels, fittings, accessories and heating controls. With state-of-the-artmanufacturing facilities and distributions centers located across North America, IPEX deliversheating solutions for a broad range of markets and applications including:

• Primary residential heating

• Supplemental floor warming systems

• Residential snow and ice melt systems – driveways, entrances

• Industrial heating for factories and warehouses

• Commercial heating systems – stores, offices

• Institutional heating for schools, hospitals, senior’s complexes

• Industrial snow and ice melt systems – parking ramps, loading docks, sidewalks

Established more than 50 years ago, IPEX’s leading position in the industry is largely due to the IPEX mission to provide its customers with the highest quality products, service and supportand to make continuous improvement a core objective of its business.

Our marketing strategy in both Canada and the United States is to supply complete systems ofpipe, fittings, accessories and all the components required for your heating project. We provideour customers with all the materials they need to ensure the integrity and high performance oftheir entire system—all designed, manufactured and backed by one company. IPEX publishestechnical design manuals, state-of-the-art IPEX Radiant™ design software, product cataloguesand supporting literature. We host comprehensive training and education programs tailored tothe needs of our distributor, installer, builder and design partners. For more information contactthe IPEX office nearest you.

SALES AND CUSTOMER SERVICE

Canadian Customers call

Toll free: (866) 473-9462

U.S. Customers call

Toll free: (800) 473-9808

About IPEX

IPEX is a leading supplier of thermoplastic piping systems. We provide our

customers with one of the world’s largest and most comprehensive product

lines. All IPEX products are backed by over 50 years of experience. With

state-of-the-art manufacturing facilities and distribution centers across

North America, the IPEX name is synonymous with quality and performance.

Our products and systems have been designed for a broad range of

customers and markets. Contact us for information on:

• Radiant heating systems

• PVC, CPVC, PP, FR-PVDF, ABS, PEX and PE pipe and fittings (¼" to 48")

• Industrial process piping systems

• Municipal pressure and gravity piping systems

• Plumbing and mechanical pipe systems

• Electrical systems

• Telecommunications and utility piping systems

• Irrigation systems

www.warmrite.com

www.ipexinc.com

This manual is published in good faith and is believed to be reliable. Data presented is the resultof laboratory tests and field experience.

IPEX maintains a policy of ongoing product improvement. This may result in modification offeatures or specifications without notice.

MNKIKWIP031206© 2004 IPEX WR003UC

$40 CDN / $26 US

manual of modern hydronic heating

Documents

wire twist ties

welded wire fabric

uneven melting patterns

hydrostatic design bases

hydronic schematic symbols

ongoing product improvement

external enable signal

indoor outdoor reset controls