Crown Boiler CWI311 User manual

CWI Series
Gas-Fired Natural Draft Water Boilers
INSTALLATION INSTRUCTIONS
These instructions must be afxed on or adjacent to the boiler
WARNING: Improper installation,
adjustment, alteration, service or
maintenance can cause property
damage, injury, or loss of life. For
assistance or additional informa-
tion, consult a qualied installer,
service agency or the gas
supplier. Read these instructions
carefully before installing.
Models:
• CWI103
• CWI138
• CWI172
• CWI207
• CWI241
• CWI276
• CWI311
• CWI346
• CWI380
Manufacturer of Hydronic Heating Products
P.O. Box 14818 3633 I. Street
Philadelphia, PA 19134
www.crownboiler.com
DESIGNED TO LEAD
9902339

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FOLLOW ALL INSTRUCTIONS and warnings
printed in this manual and posted on the boiler.
INSPECT THE BOILER ANNUALLY. To keep your
boiler safe and efficient, have a service technician
follow the Service checklist near the end of this
manual.
IF YOU ARE NOT QUALIFIED to install or service
boilers, do not install or service this one.
THE BOILER MAY LEAK WATER at the end of
its useful life. Be sure to protect walls, carpets,
and valuables from water that could leak from the
boiler.
PROTECT YOUR HOME IN FREEZING
WEATHER. A power outage, safety lockout, or
component failure will prevent your boiler from
lighting. In winter, your pipes may freeze and
cause extensive property damage. Do not leave
the heating system unattended during cold weather
unless alarms or other safeguards are in place to
prevent such damage
DO NOT BLOCK AIR FLOW into or around the
boiler. Insufficient air may cause the boiler to
produce carbon monoxide or start a fire.
KEEP FLAMMABLE LIQUIDS AWAY from the
boiler, including paint, solvents, and gasoline.
The boiler may ignite the vapors from the liquids
causing explosion or fire.
KEEP CHILDREN AND PETS away from hot
surfaces of the boiler, boiler piping, and vent pipe.
CARBON MONOXIDE (CO) is an odorless, deadly
gas that may be introduced into your home by
any malfunctioning fuel-burning product or vent
system failure. Consider installing CO alarms near
bedrooms in all levels of the building to warn you
and your family of potential CO exposure.
READ THIS ENTIRE MANUAL before attempting
installation, start-up, or service. Improper
installation, adjustment, alteration, service, or
maintenance may cause serious property damage,
personal injury, or death.
DO NOT DISCONNECT PIPE FITTINGS on the
boiler or in the heating system without first verifying
that the system is cool and free of pressure and
that your clothing will protect you from a release
of hot water or steam. Do not rely solely on the
boiler’s temperature and pressure gage when
making this judgment.
USE PROPER PERSONAL PROTECTION
EQUIPMENT when servicing or working near the
boiler. Materials of construction, flue products, and
fuel contain alumina, silica, heavy metals, carbon
monoxide, nitrogen oxides, and/or other toxic or
harmful substances that can are hazardous to
health and life and that are known to the State of
California to cause cancer, birth defects, and other
reproductive harm.
INSTALL ALL GUARDS, cover plates, and
enclosures before operating the boiler.
SIZE THE BOILER PROPERLY relative to the
design heat load or, if using domestic hot water
priority, the peak hot water load, whichever
is larger. A grossly oversized boiler will cycle
excessively and this will lead to premature failure
of the boiler and its components. Our warranty
does not apply to damage from excessive cycling.
ADHERE TO ALL LOCAL CODE
REQUIREMENTS. Contact your local code
inspector prior to installation. In the absence of
a local code, adhere to the National Fuel Gas
Code ANSI Z223.1/NFPA 54 or CAN/CSA B149.1,
Natural Gas and Propane Installation Code.
ALL WIRING must comply with the National
ElectrIcal Code ANSI/NFPA 70 (in the USA) or the
Canadian Electrical Code CSA C22.1 (in Canada)
and any local regulations.
WARNINGS FOR THE HOMEOWNER
WARNINGS FOR THE INSTALLER

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Table of Contents
I. Product Description.................................................... 2
II. Specications ............................................................. 3
III. BeforeInstalling......................................................... 4
IV. LocatingtheBoiler..................................................... 4
V. AirforCombustion&Ventilation.............................. 5
VI. Venting ....................................................................... 9
VII.GasPiping..................................................................12
VIII.SystemPiping..........................................................13
IX.TanklessHeaterPiping..............................................18
X.Wiring........................................................................20
XI.Start-Up&Checkout.................................................24
XII.Service&Maintenance.............................................30
XIII.Troubleshooting........................................................33
XIV.Parts...........................................................................40
AppendixA:KnockdownBoilerAssembly.......................46
I Product Description
 TheCWIseriesboilersarelowpressurecastirongasredhotwaterboilersdesignedforuseinclosedhotwaterheating
systems.TheseboilersareCategoryIdraftdiverterequippedappliances,whichmustbeventedbynaturaldraftusingalined
masonryorlistedmetalchimneysystem.Anadequatesupplyofairforcombustion,ventilationanddilutionofuegases
mustbeavailableintheboilerroom.
 TheCWImaybeusedonforcedorgravityhotwaterheatingsystems.CWI103-CWI279includeatanklessheaterfor
domestichotwatergeneration.ThistanklessheaterisoptionalequipmentonCWI311-CWI380

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TABLE 1: CWI SPECIFICATIONS
II Specications
FIGURE1:CWIBOILERS-GENERALCONFIGURATION
INPUT
(MBH) (MBH) (Gal/min) "A" "B" "C" "D" (Gal)
CWI103 4 103 86 83.1 2.50 16 28 407/16 5 10.0
CWI138 5 138 115 83.1 3.00 191/4 28 407/16 6 12.2
CWI172 6 172 144 83.2 3.50 221/2 28 407/16 6 14.4
CWI207 7 207 173 83.2 3.75/4.50 253/4 30 407/16 7 16.6
CWI241 8 241 201 83.2 3.75/4.75*** 29 30 407/16 7 18.8
CWI276 9 276 230 83.2 4.00/5.25*** 321/4 30 407/16 8 21.0
CWI311 10 310 252 81.4** 4.00/5.25*** 351/2 30 457/16 8 23.2
CWI346 11 345 281 81.4** 4.00/5.25*** 383/4 30 457/16 9 25.4
CWI380 12 379 309 81.4** 4.00/5.25*** 42 30 457/16 9 27.6
DIMENSIONS(in.)
AFUE
(%)
WATER
VOL.
75
100
219
TANKLESS
HTR.RATING
125
150
175
AHRINET
RATING
244
269
*CWI311-CWI380NOTAVAILABLEFORUSEWITHLPGAS
BASIC
BOILER
MODEL
NUMBER
OF
SECTIONS (MBH)
NATURALORLPGAS*
HEATING
CAPACITY
**THERMALEFFICIENCY
***RATINGWITHOPTIONAL"HIGHCAPACITY"TANKLESSHEATER
200
AHRINETRATINGSSHOWNAREBASEDONAPIPINGANDPICK-UPALLOWANCEOF1.15

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III Before Installing
1) Safe,reliableoperationofthisboilerdependsuponinstallationbyaprofessionalheatingcontractorinstrictaccordance
withthismanualandtherequirementsoftheauthorityhavingjurisdiction.
• Intheabsenceofanauthorityhavingjurisdiction,installationmustbeinaccordancewiththismanualandthe
National Fuel Gas Code,ANSIZ223.1-latestedition.
• Whererequiredbytheauthorityhavingjurisdiction,thisinstallationmustconformtotheStandard for Controls and
Safety Devices for Automatically Fired Boilers(ANSI/ASMECSD-1)-latestedition.
2) Makesurethataproperlysizedchimneyisavailablewhichisingoodcondition.Consulttheauthorityhaving
jurisdiction,PartVIofthismanual,andtheNational Fuel Gas Codeforadditionalinformationonventingrequirements.
3) Makesurethattheboileriscorrectlysized.UseanindustryacceptedsizingmethodsuchastheI=B=R Installation
Guide for Residential Hydronic Heating Systems (Pub. #200) and I=B=R Heat Loss Calculation Guide(Pub.#H21or#H22)
publishedbytheHydronicsInstituteinBerkeleyHeightsNJ.
4) Makesurethattheboilerreceivedisconguredforthecorrectgas(naturalorLP).TheCWI311,CWI346andCWI380
mayonlybeusedwithnaturalgas.
5) Boilersinstalledataltitudesabove2000ft.mayrequiredifferentburnersandmainburneroricethanthoseatsealevel.
Makesurethattheboilerisconguredforuseatthecorrectaltitude.
6) Ifthisboilerwasreceivedasaknockdownboiler,followtheinstructionsinAppendixAtoassembletheboiler.
IV Locating the Boiler
1) Clearances:
• Observetheminimumclearancesshownbelow.Theseclearancesapplytoallcombustibleconstruction,aswellas
noncombustiblewalls,ceilingsanddoors.AlsoseeFigure2.
Front–18”  
RightSide:
CWI311-CWI380withoutTanklessHeaters–18”
CWI103-CWI207withTanklessHeater-18”
CWI241-CWI380withStandardTanklessHeater-21”
CWI241-CWI380withHighCapacityTanklessHeater-24” 
LeftSide–6” 
Rear–6”  
Top–17”
• A24”serviceclearancefromthejacketisrecommendedontheleft,right,andfrontoftheboiler.Theseclearances
maybereducedtothoseshowninFigure2,howeverservicingtheboilerwillbecomeincreasinglydifcultasthese
serviceclearancesarereduced.
Warning
This Product Must be Installed By A Licensed Plumber Or Gas Fitter when Installed Within The
Commonwealth Of Massachusetts
If This Boiler is Equipped With a Tankless Heater, Tankless Heater Piping Must be Installed by a
Licensed Plumber When Boiler is Installed Within the Commonwealth of Massachusetts

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• Iftherightside24”serviceclearanceisreduced,adequateclearancemustbemaintainedtoeasilyreadandac-
cessthecontrols.Alternatively,accessmaybeprovidedusingadoor.Therightsideclearancesshownforboilers
equippedwithtanklessheatersallowforremovalofthetanklessheater.
2) Thisboilermaybeinstalleddirectlyoveranon-carpetedcombustibleoor.
3) Theboilermustbeinstalledonahardlevelsurface.
4) Donotinstallthisboilerinalocationwheregasolineorotherammablevaporsorliquidswillbestoredorused.Donot
installthisboilerinanareawherelargeamountsofairbornedustwillbepresent,suchasaworkshop.
5) Theboilershouldbelocatedasclosetothechimneyaspossible.
6) Donotinstallthisboilerdirectlyonasurfacethatmaygetwet.Raisetheboileronapad.
V Air for Combustion and Ventilation
Sufcientfreshairmustbesuppliedforcombustion,ventilationanduegasdilution.Provisionsforcombustion,ventilation
anduegasdilutionairforgasutilizationequipmentventedbynaturaldraftmustbemadeinaccordancewithlocalbuilding
codesor,inabsenceofsuchcodes,inaccordancewithsections5.3.3and5.3.4(“AirforCombustionandVentilation”)ofthe
National Fuel Gas Code,NFPA54/ANSIZ223.1.
Toensureanadequatesupplyofcombustion,ventilationanduegasdilutionairsupply,startbydeterminingwhether
theboileristobeinstalledinabuildingofunusuallytightconstruction.Agooddenitionofabuildingofunusuallytight
constructionisonewhichhasallofthefollowingfeatures:
• Wallsandceilingsexposedtooutsideatmospherehaveacontinuouswatervaporretarderwitharatingof1permor
lesswithopeningsgasketedandsealed
• Weatherstrippinghasbeenaddedonopenablewindowsanddoors
FIGURE2:CWIBOILERS-CLEARANCESTOALL
TYPESOFCOMBUSTIBLECONSTRUCTIONAND
NONCOMBUSTIBLECEILINGS,WALLS,AND
DOORS.
“X”
“X” (RH CLEARANCE)
ALL SIZES LESS TANKLESS HEATER - 18“
CWI103 - CWI241 WITH TANKLESS HTR. - 18“
CWI276 - CWI380 WITH TANKLESS HTR. - 21“
CWI207 - CWI380 WITH HIGH CAPY. TANKLESS HTR. - 24“

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• Caulkingandsealantsareappliedtoareassuchasjointsaroundwindowanddoorframes,betweensoleplatesand
oors,betweenwall-ceilingjoints,betweenwallpanels,atpenetrationsforplumbing,electrical,andgaslines,and
atotheropenings.
For Buildings of Other than Unusually Tight Construction
1) Determinewhethertheboileristobeinstalledinaconnedspace-AconnedspaceisdenedbytheNational Fuel
Gas Codeashavingavolumelessthan50cubicfeetper1000BTU/hrinputofallappliancesinstalledinthatspace.To
determinewhethertheboilerroomisaconnedspace:
a. TotaltheinputofallappliancesintheboilerroominthousandsofBTU/hr.Roundtheresulttothenexthighest1000
BTU/hr.
b. Findthevolumeoftheroomincubicfeet.Thevolumeoftheroomincubicfeetis:
 Length(ft)xwidth(ft)xceilingheight(ft)
 Incalculatingthevolumeoftheboilerroom,considerthevolumeofadjoiningspacesonlyifnodoorsareinstalled
betweenthem.Ifdoorsareinstalledbetweentheboilerroomandanadjoiningspace,donotconsiderthevolumeofthe
adjoiningspace,evenifthedoorisnormallyleftopen.
c. DividethevolumeoftheboilerroombytheinputinthousandsofBTU/hr.Iftheresultislessthan50,theboilerroomis
aconnedspace.
Example:
 ACWI172ENandawaterheateraretobeinstalledinaroommeasuring6ft-3inx7ftwithan8ftceiling.Thewater
heaterhasaninputof30000BTU/hr:
 TotalinputinthousandsofBTU/hr=(172000BTU/hr+30000BTU/hr)/1000=202
 Volumeofroom=6.25ftx7ftx8ft=350ft3
 350/202=1.73.Since1.73islessthan50,theboilerroomisaconnedspace.
2) UnconnedSpace-Naturalinltrationintotheboilerroomwillnormallyprovideadequateairforcombustionand
ventilationwithoutadditionallouversoropeningsintoboilerroom.
3) ConnedSpace-Providetwoopeningsintotheboilerroom,oneneartheoorandoneneartheceiling.Thetopedgeof
theupperopeningmustbewithin12”oftheceilingandthebottomedgeoftheloweropeningmustbewithin12”ofthe
oor(Figure3).
• Eachopeningmusthaveafreeareaof1squareinchper1000BTU/hrinputofallgasburningappliancesintheboiler
room.Theminimumopeningdimensionis3inches.Minimumopeningfreeareais100squareinchesperopening.
• Ifthetotalvolumeofboththeboilerroomandtheroomtowhichtheopeningsconnectislessthan50cubicfeetper
1000BTU/hroftotalapplianceinput,installapairofidenticalopeningsintoathirdroom.Connectadditionalrooms
withopeningsuntilthetotalvolumeofallroomsisatleast50cubicfeetper1000BTU/hrofinput.
• The“freearea”ofanopeningtakesintoaccounttheblockingeffectofmesh,grills,andlouvers.Wherescreensare
used,theymustbenonerthan¼”(4x4)mesh.
• Ifprovidingopeningsintoadjacentroomsisundesirable,combustionandventilationaircanbebroughtintotheboiler
roomfromoutdoors.Seetheinstructionsunder“ForBuildingsofUnusuallyTightConstruction”.
For Buildings of Unusually Tight Construction
1) Openingsmustbeinstalledbetweentheboilerroomandtheoutdoorsoraventilatedspace,suchasanatticorcrawl
space,whichcommunicatesdirectlywiththeoutdoors.
2) Twoopeningsarerequired.Thetopedgeoftheupperopeningmustbewithin12inchesoftheceiling.Thebottomedge
oftheloweropeningmustbewithin12inchesoftheoor.
3) Sizeopeningsandductsasfollows:
• Verticalductsoropeningsdirectlyoutdoors(Figure4,Figure5,andFigure6)-Eachopeningmusthaveafreecross
sectionalareaof1squareinchper4000BTU/hrofthetotalinputofallgas-redappliancesintheboilerroombutnot
lessthan100squareinches.Minimumopeningsizeis3inches.
• Openingstooutdoorsviahorizontalducts(Figure7)-Eachopeningmusthaveafreecrosssectionalareaof1square
inchper2000BTU/hrofthetotalinputofallgasredappliancesintheboilerroombutnotlessthan100squareinches.
Minimumopeningsizeis3inches.

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FIGURE4:ALLAIRFROMOUTDOORS,   
VENTILATEDCRAWLSPACEANDATTIC
FIGURE5:ALLAIRFROMOUTDOORS, 
VIA VENTILATED ATTIC
FIGURE3:BOILERINSTALLEDINCONFINEDSPACE,
ALLAIRFROMINSIDE

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FIGURE6:ALLAIRFROMOUTDOORS,USING
 OPENINGSINTOBOILERROOM
FIGURE7:ALLAIRFROMOUTDOORS,USING
 HORIZONTALDUCTSINTOBOILERROOM

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• The“freearea”ofanopeningtakesintoaccounttheblockingeffectofmesh,grills,andlouvers.Wherescreensare
used,theymustbenonerthan¼”(4x4)mesh.
VI Venting
Ventinstallationmustbeinaccordancewithlocalbuildingcodes,orthelocalauthorityhavingjurisdiction,ortheNational
Fuel Gas Code,NFPA54/ANSIZ223.1.
AtypicalventinstallationisillustratedbyFigure8.Thecomponentsofventinstallationaretheventdamper,ventconnector
andchimney.
1) AcceptableChimneys-ThefollowingchimneysmaybeusedtoventCWIseriesboilers:
• ListedTypeBorLgasvent-Installinaccordancewiththemanufacturer’sinstructions,thetermsofitslisting,and
applicablecodes.
• MasonryChimney-ThemasonrychimneymustbeconstructedinaccordancewiththeStandard for Chimneys,
Fireplaces, Vents, and Solid Fuel Burning Appliances(NFPA211)andlinedwithaclaylinerorotherlistedlining
system.DonotventaCWIseriesboilerintoanunlinedchimney.
2) AcceptableVentConnectors-Thefollowingmaybeusedforventconnectors:
• ListedtypeBorLGasVent
• SingleWallGalvanizedPipe-Use0.018”(26gaugeorheavier).Thesizeandlocationofthechimneymaynot
permittheuseofasinglewallconnectorinsomecases.SeetheNational Fuel Gas Code.Donotusesinglewall
pipeforventconnectorsinattics.
• OtherVentConnectorsPermittedbytheNational Fuel Gas Code.
3) ChimneyandVentConnectorSizing-SizethechimneyandventconnectorinaccordancewiththeNational Fuel Gas
Code.
4) ExteriorChimneys-Anexteriorchimneyhasoneormoresidesexposedtotheoutdoorsbelowtheroofline.Thereare
twoconditionsunderwhichanexteriorchimneymaybeused:
• In some very restrictivecases,CWIseriesboilersmaybeventedintoanexteriorceramiclinedmasonrychimney.
SeetheNational Fuel Gas Codeforinformationonwhenexteriorchimneysmaybeused.
• AnexteriormasonrychimneymaybeusedifitislinedwithBventoralistedchimneyliningsystem.
5) Thisboilermaybeventedusingalistedpowerventer.Thepowerventermustbeinsizedandinstalledinaccordance
withthepowerventermanufacturer’sinstructions,thetermsofthepowerventerlisting,andapplicablecodes.Theboiler
mustbeelectricallyinterlockedwiththepowerventertopreventboileroperationifthepowerventerfailstooperate.Before
decidingtouseapowerventer,makecertainthattheuegasexitingthepowerventerwillnotdamageadjacentconstruction
orotherstructures.Alsomakecertainthatthepowerventerterminalwillnotbesubjectedtowindswhichcouldeffectpower
venteroperation.
6) Donotconnecttheventofthisapplianceintoanyportionofamechanicalventsystemoperatingunderpositivepressure.
7) Donotconnecttheboilerintoachimneyueservinganopenreplaceorothersolidfuelappliance.
8) Priortoboilerinstallation,inspectchimneyforobstructionsorotherdefectsandcorrectasrequired.Cleanchimneyas
necessary.
9)Ventpipeshouldslopeupwardfromdraftdiverternotlessthanoneinchinfourfeet.Noportionofventpipeshouldrun
downwardorhavesags.Ventpipemustbesecurelysupported.
10) Theverticalsectionofventpipecomingofftheboilershouldbeastallaspossible,whilestillmaintainingtheproper
clearancefromthehorizontalventconnectortocombustiblesandtheproperpitchcalledforin(9)above.
11) Ventpipeshouldbeinstalledabovethebottomofthechimneytopreventblockage.
12) Ventpipemustbeinsertedushwithinsidefaceofthechimneylinerandthespacebetweenventpipeandchimney
sealedtight.
13) Donotinstalltheventdamperinanyportionoftheventsystemwhichisusedbyappliancesotherthantheboilerbeing
installed.

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14) VentdamperinstallationismandatoryonallCWIboilermodelsexcepttheCWI311-CWI380.Installventdamper(see
Figure9)asfollows:
a) Openventdampercartonandremoveinstallationinstructions.Readtheinstructionsthoroughlybeforeproceeding.
Verifythatventdamperissamesizeasdraftdiverteroutlet.SeeFigure1.Unpackventdampercarefully.Do not
force closed damper blade. Forcingventdamperclosedmayresultindamagedgeartrainandvoidwarranty.
b) Ventdamperisfactoryshippedhavingapproximately¾”diameterholeintheventdamperblade,whichmust be
left openforboilersequippedwithstandingpilot,andshouldbepluggedonboilerswithanintermittentpilot,using
theplugsuppliedwiththedamper.
Mounttheventdamperontheuecollarwithoutmodicationtoeitherandsecurewithsheetmetalscrews.Make
surescrewsdonotinterferewithdamperbladeoperation.Ventdamperbladepositionindicatormustbevisibleto
users.
c) Thedamperwireharnessisshippedwiredintotheboilerjunctionbox.Plugthelooseendofthisharnessintothe
damperandsecuretheexibleconduittothedamperusingaconnectornutprovided.
d) Installventconnectorpipeandventttingsfromventdamperoutlettochimneyorgasvent.Securewithsheetmetal
screwsandsupportasrequired.
Removing an Existing Boiler from a Common Chimney
Insomecases,whenanexistingboilerisremovedfromacommonchimney,thecommonventingsystemmaybetoolarge
fortheremainingappliances.Atthetimeofremovalofanexistingboilerthefollowingstepsshallbefollowedwitheach
applianceremainingconnectedtothecommonventingsystemplacedinoperation,whiletheotherappliancesremaining
connectedtothecommonventingsystemarenotinoperation.
a) Sealanyunusedopeninginthecommonventingsystem.
b) Visuallyinspecttheventingsystemforpropersizeandhorizontalpitchanddeterminethereisnoblockageor
restriction,leakage,corrosionandotherdeciencieswhichcouldcauseanunsafecondition.
c) Insofaraspractical,closeallbuildingdoorsandwindowsandalldoorsbetweenthespaceinwhichalltheappliances
remainingconnectedtothecommonventingsystemarelocatedandotherspacesofthebuilding.Turnonclothes
dryersandanyappliancenotconnectedtothecommonventingsystem.Turnonanyexhaustfans,suchasrange
hoodsandbathroomexhausts,sotheywilloperateatmaximumspeed.Donotoperateasummerexhaustfan.Close
replacedampers.
d) Placeinoperationtheappliancebeinginspected.Followthelightinginstructions.Adjustthermostatsotheappliance
willoperatecontinuously.
e) Testforspillageatthedrafthoodreliefopeningafterve(5)minutesofmainburneroperation.Usetheameofa
matchorcandle,orsmokefromacigarette,cigar,orpipe.
f) Afterithasbeendeterminedthateachapplianceremainingconnectedtothecommonventingsystemproperlyvents
whentestedasoutlinedabove,returndoors,windows,exhaustfans,replacedampersandanyothergas-burning
appliancestotheirpreviousconditionofuse.
g) Anyimproperoperationofthecommonventingsystemshouldbecorrectedsotheinstallationconformswiththe
NationalFuelGasCode,ANSIZ223.1.Whenresizinganyportionofthecommonventingsystem,thecommon
ventingsystemshouldberesizedtoapproachtheminimumsizeasdeterminedusingtheappropriatetablesinthe
NationalFuelGasCode,ANSIZ223.1.

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FIGURE8:CWIBOILERTYPICALVENTSYSTEM   
INSTALLATION AND COMPONENTS
FIGURE9:VENTDAMPERINSTALLATIONDETAILS

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VII Gas Piping
 Gaspipingtotheboilermustbesizedtodeliveradequategasfortheboilertoreatthenameplateinputataline
pressurebetweentheminimumandmaximumvaluesshownontheratingplate.Formoreinformationongaslinesizing,
consulttheutilityorChapter2oftheNational Fuel Gas Code.
Figure10showstypicalgaspipingconnectiontotheCWIboiler.Asedimenttrapmustbeinstalledupstreamofallgas
controls.Installamanualshut-offvalveoutsidethejacketandgroundjointunionasshown.
Theboileranditsgasconnectionmustbeleaktestedbeforeplacingtheboilerinoperation.Whendoingthis,theboilerand
itsindividualshut-offmustbedisconnectedfromtherestofthesystemduringanypressuretestingofthatsystematpressures
inexcessof1/2psi.Whenpressuretestingthegassystematpressuresof1/2psiorless,isolatetheboilerfromthegassupply
systembyclosingitsindividualmanualshut-offvalve.
FIGURE10:GASCONNECTIONTOBOILER
*StateofMassachusettsRequiresManual
Shut-offValvetobe“T”HandleType
*

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VIII System Piping
Standard Piping
 Figure11showstypicalboilersystemconnectionsonasinglezonesystem.Additionalinformationonhydronicsystem
designmaybefoundinInstallation of Residential Hydronic Systems(Pub.#200)publishedbytheHydronicsInstitutein
BerkeleyHeights,NJ.Thecomponentsinthissystemandtheirpurposesareasfollows:
1) Reliefvalve(Required)-MountthereliefvalveontherightsideoftheboilerasshowninFigure1usingthe3/4nipples
andelbowprovided.Thereliefvalveshippedwiththeboilerissettoopenat30psi.Thisvalvemaybereplacedwithone
havingapressureuptothe“MAWP,WATER”shownontheratingplate.Ifthevalveisreplaced,thereplacementmust
haveareliefcapacityinexcessoftheDOEheatingcapacityfortheboiler.
 Pipethedischargeofthereliefvalvetoalocationwherewaterorsteamwillnotcreateahazardorcausepropertydamage
ifthevalveopens.Theendofthedischargepipemustterminateinanunthreadedpipe.Ifthereliefvalvedischargeis
notpipedtoadrainitmustterminateatleast6inchesabovetheoor.Donotrunreliefvalvedischargepipingthroughan
areathatispronetofreezing.Theterminationofthereliefvalvedischargepipingmustbeinanareawhereitisnotlikely
tobecomepluggedbydebris.
2) Circulator(Required)-Althoughthecirculatorisshippedontheboilerreturn,itcanbeinstalledontheboilersupply.If
thecirculatorismovedtothesupply,itshouldbepositionedjustdownstreamoftheexpansiontankasshowninFigure
11.
3) ExpansionTank(Required)-Ifthisboilerisreplacinganexistingboilerwithnootherchangesinthesystem,the
oldexpansiontankcangenerallybereused.Iftheexpansiontankmustbereplaced,consulttheexpansiontank
manufacturer’sliteratureforpropersizing.
4) FillValve(Required)-Eitheramanualorautomaticllvalvemaybeused.Theideallocationforthellisatthe
expansiontank.
5) AutomaticAirVent(Required)-Atleastoneautomaticairventisrequired.Manualventswillusuallyberequiredin
otherpartsofthesystemtoremoveairduringinitialll.
CAUTION
• INSTALLBOILERSOTHATTHEGASIGNITIONSYSTEMCOMPONENTSAREPROTECTED
FROMWATER(DRIPPING,SPRAYING,RAIN,ETC.)DURINGAPPLIANCEOPERATIONAND
SERVICE(CIRCULATORREPLACEMENT,ETC.).
• OPERATIONOFTHISBOILERWITHCONTINUOUSRETURNTEMPERATURESBELOW120°F
CANCAUSESEVEREHEATEXCHANGERCORROSIONDAMAGE.
• OPERATIONOFTHISBOILERINASYSTEMHAVINGSIGNIFICANTAMOUNTSOFDISSOLVED
OXYGENCANCAUSESEVEREHEATEXCHANGERCORROSIONDAMAGE.
• DONOTUSETOXICADDITIVES,SUCHASAUTOMOTIVEANTIFREEZE,INAHYDRONIC
SYSTEM.
DANGER
• PIPERELIEFVALVEDISCHARGETOASAFELOCATION.
• DONOTINSTALLAVALVEINTHERELIEFVALVEDISCHARGELINE.
• DONOTMOVERELIEFVALVEFROMFACTORYLOCATION.
• DONOTPLUGRELIEFVALVEDISCHARGE.

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6) LowWaterCut-Off(Requiredinsomesituations)-Alowwatercutoffisrequiredwhentheboilerisinstalledabove
radiation.Inaddition,somecodessuchasASMECSD-1requirelowwatercutoffs.Codesmayalsorequirethatthislow
watercutoffhaveamanualresetfunction.Thelowwatercutoffmaybeaoattypeorprobetype,butmustbedesigned
foruseinahot-watersystem.Thelowwatercutoffshouldbepipedintotheboilersupplyjustabovetheboilerwithno
interveningvalvesbetweenitandtheboiler.
 Usealowwatercutoffthatbreaksthe120VACsupplytotheboiler.Donotattempttowirea24-voltlowwatercutoff
intotheboilerfactorywiring.
7) ManualResetHighLimit(Requiredbysomecodes)-ThiscontrolisrequiredbyASMECSD-1andsomeothercodes.
Installthehighlimitintheboilersupplypipingjustbeyondtheboilerwithnointerveningvalves.Setthemanualreset
highlimitasfarabovetheoperatinglimitsettingaspossible,butnotover240°F.Wirethecontroltobreakthe120VAC
electricalsupplytotheboiler.
8) FlowControlValve(Requiredundersomeconditions)-Theowcontrolvalvepreventsowthroughthesystemunless
thecirculatorisoperating.Aowcontrolvalvemaybenecessaryonconvertedgravitysystemstopreventgravity
circulation.Flowcontrolvalvesarealsousedtoprevent“ghostows”incirculatorzonesystemsthroughzonesthatare
notcallingforheat.
9) IsolationValves(Optional)-Isolationvalvesareusefuliftheboilermustbedrained,astheywilleliminatehavingtodrain
andrelltheentiresystem.
10) DrainValve-Thedrainvalveisshippedintheboilerpartsbag.Installitintheteeunderthecirculatorasshownin
Figure1.
Piping for Special Situations
Certaintypesofheatingsystemshaveadditionalrequirements.Someofthemorecommonvariationsfollow:
1) IndirectWaterHeaters-Figure12showstypicalindirectwaterheaterpiping.Boilerpipingisthesameasforanytwo-
zonesystem.Figure12showscirculatorzoning,whichisusuallypreferredforindirectwaterheaters.Sizethecirculator
andindirectwaterheaterpipingtoobtaintheboilerwaterowthroughtheindirectwaterheatercalledforbytheindirect
waterheatermanufacturer.
2) LargeWaterVolumeSystems-ThepipingshowninFigure13willminimizetheamountoftimethattheboileroperates
withreturntemperaturesbelow120°Fonthesesystems.Abypassisinstalledasshowntodivertsomesupplywater
directlyintothereturnwater.Thebypasspipeshouldbethesamesizeasthesupply.Thetwothrottlingvalvesshownare
adjustedsothatthereturntemperaturerisesabove120°Fduringtherstfewminutesofoperation.Athree-wayvalvecan
besubstitutedforthetwothrottlingvalvesshown.Ifthecirculatorismountedonthesupply,thebypassmustbeonthe
dischargesideofthecirculator.
3) LowTemperatureSystems-Somesystems,suchasradianttubingsystems,requirethesystemwatertemperatureto
belimitedtoavaluebelowthetemperatureofthewaterleavingtheCWI.Thesesystemsalsotypicallyhavereturn
temperatureswellbelowthe120°Fminimum.
 Figure14illustratestheuseofaheatexchangertoconnecttheCWIboilertothistypeofsystem.Theheatexchanger
willpermitthetransferofheatfromtheboilerwatertothelowtemperaturesystemwhileholdingthesystemsupplyand
boilerreturntemperatureswithintheirlimits.Forthissystemtoworkproperlytheheatexchangermustbeproperlysized
andthecorrectowratesarerequiredoneithersideoftheheatexchanger.Consulttheheatexchangermanufacturerfor
sizinginformation.Thewaterintheboileriscompletelyisolatedfromthewaterinthesystem.Thismeansthatseparate
llandexpansiontanksarerequiredfortheheatingsystemloop.
 Thereareseveralotherwaystoconnectlowtemperaturesystemstonon-condensingboilersliketheCWI,suchasfour
waymixingvalveandvariablespeedinjectionpumpingsystems.
4) Systemscontainingoxygen-Manyhydronicsystemscontainenoughdissolvedoxygentocauseseverecorrosiondamage
toacastironboilersuchastheCWI.Someexamplesinclude:
• Radiantsystemsthatemploytubingwithoutanoxygenbarrier.
• Systemswithroutineadditionsoffreshwater.
• Systemswhichareopentotheatmosphere.
 Iftheboileristobeusedinsuchasystem,itmustbeseparatedfromtheoxygenatedwaterbeingheatedwithaheat
exchangerasshowninFigure14.
 Consulttheheatexchangermanufacturerforproperheatexchangersizingaswellasowandtemperaturerequirements.
Allcomponentsontheoxygenatedsideoftheheatexchanger,suchasthepumpandexpansiontank,mustbedesignedfor
useinoxygenatedwater.

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FIGURE12:INDIRECTWATERHEATER 
 BOILERSIDEPIPING
FIGURE11:STANDARDBOILERPIPING

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5) PipingwithaChiller-Iftheboilerisusedinconjunctionwithachiller,pipetheboilerandchillerinparallelasshownin
Figure15.Useisolationvalvestopreventchilledwaterfromenteringtheboiler.
6) AirHandlers-Wheretheboilerisconnectedtoairhandlersthroughwhichrefrigeratedairpasses,useowcontrolvalves
intheboilerpipingorotherautomaticmeanstopreventgravitycirculationduringthecoolingcycle.
7)GravityHotWaterSystems-TheCWIissuitableforinstallationinagravityhotwatersystem.Figure16showspiping
foragravityhotwaterboiler.Thecirculator,1-1/2”x2”bushings,and1-1/2”pipingareremovedandthesystempipingis
rundirectlytothe2”supplyandreturntappingsontheboiler.Ifisolationvalvesareinstalled,theyshouldbegatevalves
or“fullport”ballvalves.
 Ifitisdesiredtoconvertthegravitysystemtoforcedhotwater,thefactorysuppliedcirculatorandpipingareusedasis.
Agravityhotwatersystemisa“largewatervolumesystem”(see(2)above)andshouldbepipedwithabypassasshown
inFigure13.Manygravityhotwatersystemshavebalancingoriceinstalledintheradiators.Theseoricemayneedto
beremovedtoobtainproperheatdistributionwhenthesystemisconvertedtoforcedhotwater.
FIGURE13:BOILERBYPASSPIPING

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FIGURE15:BOILERPIPINGWITHCHILLER
FIGURE14:ISOLATIONOFBOILERFROMSYSTEMWITHAHEATEXCHANGER

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IX TANKLESS HEATER PIPING
IftheCWIissuppliedwithatanklessheater,pipetheheaterasshowninFigure17.Thecomponentsinthissystemand
theirfunctionsareasfollows:
1)MixingValve(Required)-Duringtheheatingseason,thewaterexitingthetanklessheatermaybe180degreesormore.
Themixingvalveblendshotwaterleavingthetanklessheaterwithcoldwatersoastomaintainthehotwatersupplied
tothexturesataxedtemperature.Thissavesenergy,increasestheamountofusablehotwateravailabletothe
homeowner,andreducestheriskofscalding.
Installamixingvalvewithasettingrangeofapproximately110to130F.Followthemanufacturer’sinstructionsfor
installingthisvalve.Usuallya“heattrap”willberequiredbetweenthecoilandthe“hot”connectiononthemixingvalve.
2)FlowRestrictor(Recommended)-IfwaterisdrawnfromthetanklesscoilatarateinexcessoftheratinginTable1,
thetemperatureofthehotwatermaybetoolowtobeofuse.Theuseofaowrestrictorwillpreventthisproblemby
limitingtherateatwhichwatercanpassthroughthetanklessheater.Ifarestrictorisused,selectonehavingaratingin
GPMapproximatelyequaltotheratingshowninTable1.Ifpossible,locatethisrestrictoratleast3feetfromthetankless
heaterinletsothatitisnotsubjectedtoexcessivetemperatureswhennowaterisowingthroughthecoil.
FIGURE16:GRAVITYPIPING