A.O. Smith 310 - TEMPERATURE FLUCTUATES WHEN A FIXTURE IS OPENED

TroubleshootingGuide
9|Page
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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pa neloftheunit.
TEMPERATUREFLUCTUATESWH EN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:
o Checkforcrossplumbingbetweencoldwaterlinesandhotwaterlines.Seethe
Proceduressection(p.21)forinstructions.
o 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.
o Problems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
o Verify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).
o ForLPmodels,theremay
notbeenoughgasleftinthepropanetank.
o Verify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
o Verifythattheexhaustventingisinstalledtomanufacturer’sspecification.
o Verify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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