Specifications

TroubleshootingGuide

16|Page

2) Checkthegassupply.Verifythatsufficientgasisbeingsuppliedtotheheaterandthegaslineis
clearedofdebris.
a. Itispossiblethereisafaultypressureregulatoratthegasmeter.
b. Forpropaneunits,colderperiodsofthedayresultinacoldregulator
andmaycausethis
problem.
3) Verifythatthegassupplypressureiswithin
specificationswhentheheaterisinstandbyand
whentheheaterisrunning.
4) Checkthattheclearplastictubeconnectingthe
proportionalgasvalvetothecombustionchamber is 
attached.
5) Iftheflamecomes
onfor1‐2secondsbutthengoes
out,cleantheflamesensor(p.27).
6) Theoverheatcutofffusemayhavebeen
compromised.Forproceduresonhowtocheck
whethertheOHCFisintact,refertop.26.Ifithas,
contactthetechnicalservicedepartmentforfurther
assistance.
7)
Checkforblockagesinventing,suchasbirdnests,animals,ortrash.
8) PCBoardfaultorGasSolenoidfault.
a. Ifoneoftheseissuspectedtobetheproblem,contactthetechnicalservicedepartment.

ERRORCODE311:OUTPUTTHERMISTOR
1) Checkthatthewireconnectionsaresecureandfree
ofburnsorcuts.Theoutputthermistorislocatedon
theheatexchangerontherightside.

2) Checktheresistancevalue;itshouldbeabout9.0kΩ
atroomtemperature(about74°F).
3) Cleanthethermistor.
a. Draintheunitofwater.Seep.23.
b. Removethefastenerholdingtheoutput
thermistorandpulloutthesensorprobe.Clean
theprobetoasilverfinish.Do
notlosethe
rubbero‐ringthatwrapsaroundthissensor.
c. Replaceandtest.
4) Iftheerrorcodepersists,replacethethermistor.

ERRORCODE321:INLETTHERMISTOR
1) Checkthatthewireconnectionsaresecureandfreeofburnsorcuts.Theinletthermistoris
embeddedinthewaterinletconnection.
2) Checktheresistancevalue;itshouldbeabout9.0kΩatroomtemperature(about74°F).
3) Cleanthethermistor.
a. Draintheunitofwater.Seep.
23.
b. Removethecomputerboardtoaccesstheinletthermistor.Thecomputerisfixedinplacebya
singlescrewatthetopoftheboard.
c. Removethescrew,pulloutthesensorprobe.Cleantheprobetoasilverfinish.Donotlosethe
rubbero‐ring
thatwrapsaroundthissensor.
d. Replaceandtest.

Figure10
Figure11