Rheem RTGH-RH11DV - Chapter 4: Troubleshooting - Overheat Protection; Er:20 High Limit Switch Abnormality

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Errorcode Meaning Condition
HighLimitSwitchAbnormality
(Manualrestore)
WhentheHighLimitSwitch
temperatureisoverheated,error
code20willappear.
Failureevent
AnEr.20willdisplayifthetemperatureoftheheatingwaterexitingtheprimaryheatexchangerexceeds
theHighLimitSwitch'sdefaultsettings.Combustionwillstopandthefanwillcontinuetorunforpost-
purge.
Checkpoint
①InspecttheHighLimitSwitchwhenerrorcodeappearseven
iftheheatingsupplytemperatureisnottoohigh.
②Checkconnectorandifnoproblem,measureHighLimit
Switchlocatedatheatexchangeroutletandreplacewhenthe
multi-metervalueshows'0L'.(Normalvalueis'0~0.5Ω'.)
(CN11:red⑧,⑯)
③Checkthecirculationpumpspeedsettingasspeed.
Chapter4Troubleshooting
HighLimitSwitch
(203℉/95℃)
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