A.O. Smith 110 User manual

TroubleshootingGuide
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Non‐CondensingModels
On‐DemandWaterHeater
TroubleshootingGuide
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110Indoor(T‐KJr2‐IN)   110Outdoor(T‐KJr2‐OS)
310Indoor(T‐K4‐IN)310Outdoor(T‐K4‐OS)
510Indoor(T‐D2‐IN)510Outdoor(T‐D2‐OS)
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9/12/11321923‐000
A.O. SmithWaterProductsCompany
500TennesseeWaltzParkway
AshlandCity,TN37015
TollFree:1‐877‐737‐2840
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
AO Smith general troubleshoot guide

TroubleshootingGuide
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TableofContents
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1. SPECIFICATIONS.……………………………………………………………………………..……………………3
2. INTRODUCTION.…………………………………………………………………………………..………………4
3. NORMALOPERATION…………….………………………………………………………………………..…..5
Activation………………………………………………………………………………………………….5
Operation..………………………………………………………………………………………………..5
Shutdown……….………….………….……………………………………………………………..…..5
4. INSTALLATION….…………………………………………………………………………….…………………….6
Venting…………….………………………………………………………………………………..…..…6
GasLine…………….………………………………………………………………………………………6
WaterLine……………………..…….……………………………………………………………..…..6
PowerSupply..…………………………………………………………………………………………..6
5. TROUBLESHOOTING....…………………………………………………………………………………………7
PreliminaryChecklist.………………………………………………………………………..…..…7
GeneralProblems..……………………………………………………………………………………8
ErrorCodes.………………………….……………………………………………………………..….12
Procedures.……..……………………………………………………………………………………….19
VerifyingproperDipswitchsettings...……………………..………………….…19
Drainingtheunit...…………………………………………………………………………21
Cleaningthefilter..………………………………………….…………………………….21
CheckingforaCrossConnection..………………………………………….………21
CheckforReverseConnection..………………………………………….………….21
Checkgassupplypressure……..…………………………………….……………….21
Purgethegaslineofair…………..……………………………….…………………..22
Adjustingmanifoldpressure……..…………………………………….…………….22
Resettingthecomputerboard……..…………………………………….…………23
CheckingtheOHCF………………………..….………………………………………….24
6. MAINTENANCE….…..……………………………………………….……………………………………….……25
RodAssembly..…………………………………………………………………………………..…..…25
Burner&RodAssembly…..………………………………………………………………………..26
HeatExchanger…..….…………….……………………………………………………………..…..29
FlowSensor….….………………………………………………………………………………………..31
DescalingtheUnit……………………………………………………………………………………..32
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TroubleshootingGuide

TroubleshootingGuide
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1.SPECIFICATIONS
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Table1

TroubleshootingGuide
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2.INTRODUCTION
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Thismanualprovidesthenecessaryinformationfortroubleshootingthe110(T‐KJr2),310(T‐K4),510(T‐
D2)tanklesswaterheaters.Itwillbeeffectiveinhelpingyourtroubleshootingneedsaslongasthe
instructionsarefollowedintheintendedorder.Hereishowtousethismanual:
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•FirstrefertotheInstallationManualastheprimarysourceofinformation.Refertoitalongside
thismanualthroughoutthetroubleshootingprocess.
•Beforetroubleshooting,ifyouareunfamiliarwithhowatanklessunitoperates,readtheNormal
Operationsection(p.5).
•Todouble‐check/troubleshootanewinstallation,usetheProperInstallationsection(p.6).
•Whenbeginningtroubleshooting,firstgothroughthePreliminaryChecklist(p.7);itisdesigned
tofixthemostcommonandfrequentproblems,andprovideyouwithbackgroundinformation
tohelpnarrowdowntheinformationyouneed.
•AfterthePreliminaryChecklist,movetotheErrorCodessection(p.12)ifyouhavereceivedan
errorcode,ortoGeneralProblems(p.8)ifyouhavenotreceivedanerrorcode.
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Ifyouhaveanyproblemsorquestionsregardingthisequipment,oratanypointbecomeconfusedor
uncomfortablewithanyoftheprocedures,consultwiththetechnicalservicedepartmentorservice
agent.
IMPORTANT
•Installationandservicemustbeperformedbyaqualifiedinstaller(for
example,alicensedplumberorgasfitter).Otherwisethewarrantywill
bevoid.
•Theinstaller/serviceagent(licensedprofessional)isresponsiblefor
correctlyinstallingorservicingyourwaterheaterandforcompliance
withallnational,state/provincial,andlocalcodes.
*ForallunitsinstalledinthestateofMassachusetts,itisrequiredthattheinstallereitherbea
licensedplumberorlicensedgasfitter.
GENERALINSTALLATIONGUIDELINES
1. Followalllocalcodes,orintheabsenceoflocalcodes,followthemostrecenteditionofthe
NationalFuelGasCode:ANSIZ223.1/NFPA54intheUSAorCAN/CSAB149.1NaturalGas,Propane
InstallationCodeinCanada.
2. Properlygroundtheunitinaccordancewithalllocalcodesorintheabsenceoflocalcodes,with
theNationalElectricalCodes:ANSI/NFPA70intheUSAorCSAstandardC22.1CanadaElectrical
CodePart1inCanada.
3. Carefullyplanwhereyouintendtoinstallyourwaterheater.
4. ChecktheratingplateforthecorrectGASTYPE,GASPRESSURE,WATER
PRESSUREandELECTRICRATING.
*Ifthisunitdoesnotmatchyourrequirements,donotinstall.
5. Ifanyproblemshouldoccur,turnoffallhotwatertapsandturnoffthe
gas.Thencallatrainedtechnicianorthegascompany.
WARNING
RATING
PLATE
Figure1

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3.NORMALOPERATION
Becomingfamiliarwithhowatanklesswaterheaternormally
operatesmayhelptofigureoutwhatiswrongwithit.
Assumingitisproperlyinstalledwithappropriategas,water,
andelectricconnections,thefollowingishowitshould
operate:
1) ACTIVATION
a. Ahotwatertapisopenedenoughthattheflow
sensordetectsaflowratethroughtheheatergreater
thantheactivationpointof0.75gpm.
b. Thefanactivatesafterflowisdetected.
c. Thecomputerchecksforanyproblemswiththeunit
beforestartup.
d. Igniteractivates.Youcanhearthebuzzingofthe
sparkigniter.
e. Maingasvalve,proportionalvalve,andsolenoidgas
valveswillopen.Youwillhearadeep“clunkclunk”
noise.
f. Onceaflameisdetected,theredLEDlocatedonthe
computerboardwillactivate.
g. Inamulti‐heatersetup,thecontrollerwillactivatethe
nextheaterin2‐4gpmincrements,dependingonthe
settemperature.
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2) OPERATION
a. Theproportionalgasvalvewillmodulatebasedontheamountofhotwaterdemandedandthe
temperatureriseneeded.Thefanspeedwillmodulateaswelltocreateanefficientburn.
b. Youwillnoticethatonlypartialsectionsoftheburnerwillbelit.Thisisnormaloperation;there
arethreesectionsontheburnerassembly,andthecomputercontrolstheamountofsections
neededbasedontheflowrateandtemperatureriserequired.
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3) SHUTDOWN
a. Theheaterwillshutdownwhenthewaterflowratedropsbelowthedeactivationpointof
0.4gpm.
b. Theheaterwillclosethemaingasvalveandsolenoidgasvalves,extinguishingtheflame.
c. WhentheflamedisappearstheredLEDwillturnoff.
d. Thefanwillincreaseinspeedtopurgetheventingofanyremainingexhaustgases.Thelength
ofpost‐purgecanlastupto1½minutes.
e. Theheatergoesintostandbywaitingfortheprocesstobeginagain.
*Thepurposeofthisdiagramistoillustratethe
tanklesswaterheaterdesignconcepts,and
maynotbeaccuratetoyourmodelsphysical
description.
Figure2

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4.INSTALLATION
1. Followalllocalcodes,orintheabsenceoflocalcodes,followthemostrecenteditionofthe
NationalFuelGasCode:ANSIZ223.1/NFPA54intheUSAorCAN/CSAB149.1NaturalGas,
PropaneInstallationCodeinCanada.
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2. Allgaswaterheatersrequirecarefulandcorrectinstallationtoensuresafeandefficient
operation.Thismanualmustbefollowedexactly.Readthe“SafetyGuidelines”sectioninthe
installationmanual.
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3. Themanifoldgaspressureispresetatthefactory.Itiscomputercontrolledandshouldnot
needadjustment.
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4. Maintainproperspaceforservicing.Installtheunitsothatitcanbeconnectedorremoved
easily.RefertotheClearancesSectiononp.8intheinstallationmanualforproperclearances.
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5. Thewaterheatermustbeinstalledinalocationwheretheproperamountofcombustibleair
willbeavailabletoitatalltimeswithoutobstructions.
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6. Theelectricalconnectionrequiresameansofdisconnection,toterminatepowertothewater
heaterforservicingandsafetypurposes.
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7. Donotinstalltheunitwheretheexhaustventispointingintoanyopeninginabuildingorwhere
thenoisemaydisturbyourneighbors.Makesuretheventterminationmeetstherequired
distancebylocalcodefromanydoorwayoropeningtopreventexhaustfromenteringa
building.
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8. Particlesfromflour,aerosols,andothercontaminantsmayclogtheairventorreducethe
functionsoftherotatingfanandcauseimproperburningofthegas.Regularlyensurethatthe
areaaroundtheunitisdust‐ordebris‐free;regularmaintenanceisrecommendedforthese
typesofenvironment.

9. Ifyouwillbeinstallingthewaterheaterinacontaminatedareawithahighlevelofdust,sand,
flour,aerosolsorothercontaminants/chemicals,theycanbecomeairborneandenterandbuild
upwithinthefanandburnercausingdamagetothewaterheater.

10. FortheIndoor110(T‐KJr2‐IN),310(T‐K4‐IN),and510(T‐D2‐IN)models:
•Theseunitsmaybeconvertedtoadirect‐vent(sealedcombustion)appliancebyinstallinga
direct‐ventconversionkit(PartNo.9007667005)whichwillbringinallrequired
combustibleairfromoutsidethebuilding.Wheninstallingtheconversionkit,pleasefollow
allinstructionsincludedwiththekit.
•Ifthewaterheaterisusedasadirect‐ventappliance,theunitrequiresa3”intakeairpipe.
Theintakepipemustbesealedairtight.AirsupplypipecanbemadeofABS, PVC,
galvanizedsteel,corrugatedaluminum,corrugatedstainlesssteelorCategoryIIIstainless
steel.
•Terminatingtheventingthroughasidewallisrecommendedforthedirect‐ventsystem.
•Runningtheexhaustventandtheintakepipeparallelisrecommended.
•Terminatingtheexhaustandintakeonthesamewall/surfaceisrecommended.
Terminatinginthesamepressurezoneallowsforpressurebalancing,whichprevents
nuisanceshutdowns.Followventingclearanceguidelinesintheinstallationmanual.

11. ForOutdoor110(T‐KJr2‐OS),310(T‐K4‐OS),&510(T‐D2‐OS):
•Tobeinstalledoutdoorsandonlyinareaswithmild,temperateclimates.

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5.TROUBLESHOOTING
5.1PRELIMINARYCHECKLIST
Checkallofthesebasicitemsbeforeproceedingontoanyothersection:
•GAS/WATER/ELECTRIC:
oThegassupplyvalveshouldbefullyopen.
oVerifythecorrectgastypeisbeingused,NGorLP.
oThewatersupplyvalveshouldbefullyopen.
oTheunitshouldbeconnectedtoa120VAC60Hzpowersupply.Thiscanbeverifiedby
observingthecomputerboard3‐digitLEDdisplay.Ifitisnotlit,thecomputerboardis
notbeingpowered.ChecktoseeiftheON/OFFswitchbelowthefuseboxissettothe
onposition,orifthefuseinthefuseboxisblown.
•REMOTE:Ifyouareusingaremotecontroller,theremote’spowerbuttonmustbeturnedon.
•HIGHALTITUDE:Isyourlocationatanaltitudeofover3000feet?Thismaycausealackofair.
SeethehighaltitudeprocedureintheTroubleshootingProceduressection.
•HARDWATER:Whatisthehardnessofthewater?Asoftenerisalwaysrecommended,butif
thewaterisabove7grainsofhardnessor70‐140ppm,onemustbeinstalled.Ifthereisno
watersoftenerinstalled,existinginstallationswillgraduallyaccumulatescalebuilduponthe
heatexchangerandcausealeak.Heatexchangerfailuresdotohardwaterscalearenot
coveredunderthewarranty.
•NEWINSTALLATIONS:Isthisinstallationafewyearsoldorbrandnew?
oAunitthathasworkedproperlyforawhilebutisnowstrugglingmayhavebecome
scaleduporcontainsadirtyburner.
oAnewinstallationmostlikelyisinstalledorplumbedincorrectly.
•EXTERNALPROBLEM:Testwhethertheproblemiswithintheunitorexternaltotheunit(i.e.in
theplumbingsystem)byattemptingtorunhotwaterlocallythroughthepressurereliefvalve
(PRV).
oDoestheheaterigniteandremainrunningproperly?Ordoestheheatershutdowninto
anerrorcode?IfitrunsfinethroughthePRVtheplumbingsystemisatfault.


NEXTSTEP:Finally,checktoseeiftheunithasanerrorcode.Theerrorcodewillbedisplayedonthe
sevensegmentLEDonthebottomleftofthecomputerboard.Seefigures4and5.
•Ifitisdisplayinganerrorcode,proceedtotheErrorCodessection(p.12).
•Ifthereisnoerrorcode,proceedtotheGeneralProblemssection(p.8).
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5.2TROUBLESHOOTING‐GENERALPROBLEMS
ProceedtotheErrorCodessectionifanerrorcodeisidentified.Forothercommonproblemsthatdo
notinvolveanerrorcode,seeifthefollowingitemshelp:
Thewaterisnothotenough.
Thewateristoohot.
Temperaturefluctuateswhenafixtureisopened.
Unitdoesnotignitewhenwatergoesthroughit.
Ittakesalongtimetogethotwateratthefixtures.
Thefanmotorisstillspinningafteroperationhasstopped.
Abnormalsoundscomefromtheunit.
Lossofpressureatallsinkswhenthedishwasherfills.
Unithaspower,gas,andwaterbutdoesnotturnon.
MultipleHeaterSetup(Easy‐Link)
THEWATERISNOTHOTENOUGH
•Comparetheflowandtemperatureatthepressurereliefvalve.
oIfthetemperatureandflowratearecorrectatthePRVthentheproblemresidesinthe
plumbingline,notinthetanklessunit.Checkforacrossconnectionorotherwaterline
problems
•Testthehotwatertemperaturewithahandheldthermometertomeasurehowfaroffthewater
temperatureisfromthesettemperature.
oThesettemperaturemaybesettoolow.Thetemperaturecanbechangedwiththe
pushbuttonsonthePCBorbytheremotetemperaturecontroller,ifoneisinstalled.
•Checkforcrossplumbingbetweencoldwaterlinesandhotwaterlines.SeetheProcedures
section(p.21)forinstructions.
•Unitmaybehardwaterscaled.Thescaleactsasaninsulatorpreventingtheheatexchanger
fromtransferringheattothewater.ContactaTakagiServiceAgent.
•Theunitmaynotbereceivingenoughgas.
oThegassupplyvalvemaynotbefullyopen.
oThegaslinemaybesizedimproperly.
oThegassupplypressuremaybetoolow.Thismaybecausedbyamalfunctioninggas
supplyregulator,sochecktoseeifyourregulatorisworkingproperly.
•Checktoseethatacheckvalveisinstalledbetweenthepumpdischargeandtheconnectionto
thecoldwatersupply.Inspectthecheckvalveforproperoperation.Ifthereisn’toneinstalled,
orifitismalfunctioning,coldwatermaybeback‐feedingintothesystem.
•Double‐checkfora101errorcode.A101errorcodewillreducetheamountofgasinputinto
theheater.
•Outputtemperaturewillbeaffectedifairflowisimpeded.
oCheckconstructiondustanddebrisinventing,suchasdrywall.
oIfthereisdustinsidethecabinet,therewillalsobedustinsidetheburnerandheat
exchanger.Seetheprocedureforcleaningtheburner(p.26).

THEWATERISTOOHOT
•Thesettemperaturemaybesettoohigh.Thetemperaturecanbechangedwithdipswitcheson
thePCBorbytheremotetemperaturecontroller,ifoneisinstalled.

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•Theflowadjustmentvalvecouldbeobstructedduetohardwaterscaleordebris,causinglower
thanexpectedwaterflow.Verifywaterflowwithagraduatedcontainerorwiththeremote
temperaturecontroller,ifoneisinstalled.
•Theoutputthermistorcouldbecompromised.Thiscomponentmaybecheckedbyenteringthe
DiagnosticsModeonaremotecontroller,ifoneisinstalled.Turnpowerofftotheunitandrun
coldwaterthroughit;checktoseeiftheinletandoutlettemperaturesreadthesameonthe
remote.Forinstructionsonhowtodothis,refertotheMaintenanceSheet,packagedwith
everywaterheaterandlocatedbehindthefrontpaneloftheunit.
TEMPERATUREFLUCTUATESWHENAFIXTUREISOPENED
•MakesuretheunitisinstalledproperlyusingtheProperInstallationsection(p.6)ofthisguide.
•Checktheflowandtemperaturerightattheunitatthepressurereliefvalve.Iftheflowrate
andtemperaturearecorrectatthePRV,thentheproblemresideselsewhereintheplumbing
line.Thefollowingcouldbeplumbinglineproblems:
oCheckforcrossplumbingbetweencoldwaterlinesandhotwaterlines.Seethe
Proceduressection(p.21)forinstructions.
oChecktoseethatacheckvalveisinstalledbetweenthepumpdischargeandthe
connectiontothecoldwatersupply.Inspectthecheckvalveforproperoperation.If
thereisn’toneinstalled,orifitismalfunctioning,coldwatermaybeback‐feedinginto
thesystem.
oProblemswitharecirculationsystem:
Checkthatacheckvalveisinstalledbetweenthepumpdischargeandthe
connectiontothecoldwatersupply.
Checktoseeifthepumpisoperatingproperly.
Checkforaircavitation.Thepumpwillbeveryhotorchattering.
Checkthedirectionalindicatoronthepumpflange.
Checkthesizingofthepump–aminimumflowof2gpmisrequired.
•Checkgassupply
oVerifythegassupplylinesaresizedforthemaximumBtu/hdemand,asindicatedinthe
ProperInstallationsection(p.6)ofthisguide(Seethespecificationpagep.3atthe
beginningofthismanualforgasinputrating).
oForLPmodels,theremaynotbeenoughgasleftinthepropanetank.
oVerifythatthesupplygaspressureiswithinspecification,notonlywhentheheaterisin
standby,butwhiletheheaterisrunningonmaximumfireaswell.Thismaybecaused
byamalfunctioninggassupplyregulator.
•Venting
oVerifythattheexhaustventingisinstalledtomanufacturer’sspecification.
oVerifythattheventrundoesnotexceedthemaximumlimit(50ft.)
•Thefilteroncoldwaterinletshouldbeclean;lookforsignsofhardwaterscaling.
•Checktomakesurethatthecleartubebetweentheproportionalgasvalveandthebottomof
thecombustionchamberisconnected.
•Onwellsystemsorevenonsomecitywatersystems,waterpressurefluctuations(especiallyon
lowflow)of8to10psiwillresultinflowratefluctuations,whichwillinturnresultinminor
temperaturefluctuations.
•Flowsensororwatercontrolvalvemaybecompromised.ContacttheTechnicalDepartment.
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TroubleshootingGuide
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UNITDOESNOTIGNITEWHENWATERGOESTHROUGHIT
•Istheflowrateover0.75gpm?Seeiftheunitinitiateswhenyouincreasedemandofwater
beingdrawnthroughtheunit(e.g.openingupmorehotfixtures).
•Checkthatthegaslineisopenandispurgedofair(p.22).
•Checkthatthefilteronthecoldwaterinletisclean(p.21).
•Checkforreverseconnectionandcrossconnection(p.21).
•Problemswithrecirculationsystem
oSeethatacheckvalveisinstalledbetweenthepumpdischargeandtheconnectionto
thecoldwatersupply.Amalfunctioningormissingcheckvalvewillcausecoldwaterto
back‐feedintothesystem.
•Ifyouusetheremotecontroller,istheremotepowerbuttonturnedon?
•ChecktoseeiftheComputerboardisreceivingpower.Thiscanbeverifiedbyobservingthe
computerboardredLED.
oIfitisnotlit,thecomputerboardisnotbeingpowered.ChecktoseeiftheON/OFF
switchbelowthefuseboxissettotheonposition,orifthefuseinthefuseboxis
blown.
•Ifthefandoesnotinitiateatallanditisverifiedthattheunitispowered(seeabove),theflow
sensormaynotbeworkingproperly.Checktheflowsensorforproperimpellerfunctionality.
ITTAKESALONGTIMETOGETHOTWATERATTHEFIXTURES
•Thetimeittakestodeliverhotwatertoyourfixturesdependsonthelengthofpipingbetween
thetwo.Thelongerthedistanceorthebiggerthepipes,thelongeritwilltaketogethotwater.
Ifthisisthecaseandyouwouldliketoreceivehotwatertoyourfixturesquicker,youmaywant
toconsiderahotwaterrecirculationsystem.
•Problemswiththerecirculationsystem.
oSeethatacheckvalveisinstalledbetweenthepumpdischargeandtheconnectionto
thecoldwatersupply.Amalfunctioningormissingcheckvalvewillcausecoldwaterto
back‐feedintothesystem.
THEFANMOTORISSTILLSPINNINGAFTEROPERATIONHASSTOPPED
•Thisisnormal.Afteroperationhasstopped,thefanmotorkeepsrunning
from5to50secondsinordertore‐ignitequickly,aswellaspurgeallthe
exhaustgasoutoftheflue.
ABNORMALSOUNDSCOMEFROMTHEUNIT
•Checkthefanfordebris.
•ContacttheTechnicalServiceDepartment.
LOSSOFPRESSUREATALLSINKSDURINGCOMMERCIALDISHWASHERFILLS
•Verifythecapacityoftheheater(s)versustheGPMdemandofthedishwasher.
•Checkthesizeofthesupplylinestothedishwasher.
•Lookforawaterregulatoronthedishwasher.Checkthedishwasherratingplatetoconfirmthe
recommendedsupplywaterpressure.
•Unitmaybehardwaterscaled.Scalecanreducepressureandflowofwaterthroughtheunit;
thiscanoccurasquicklyasafewmonths.
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Figure3