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Combustion Air Temperature Thermistor
34
Fault
•
Check for restrictions in air flow around
unit and vent terminal.
•
Check sensor wiring for damage.
•
Measure resistance of sensor.
•
Ensure fan blade is tight on motor shaft
and is in good condition.
•
Replace sensor if necessary.
Freeze Protection Thermistor
41
•
Check sensor wiring for damage.
•
Measure resistance of sensor. (See
Electrical Diagnostics)
•
Replace sensor if necessary.
Inlet Water Temperature Thermistor
51
•
Check sensor wiring for damage.
•
Measure resistance of sensor. (See
Electrical Diagnostics)
•
Replace sensor if necessary.
Modulating Solenoid Valve Signal
52
•
Check modulating gas solenoid valve
wiring harness for loose or damaged
terminals.
•
Measure resistance of valve coil.
Combustion Fan
61
•
Ensure fan will turn freely.
•
Check wiring harness to motor for
damaged and/or loose connections.
•
Measure resistance of motor winding.
Recirculation Low Flow
63
•
Ensure the inlet water filter is clean and
free of debris.
•
Ensure parameter setting are correctly
set for recirculation mode.
•
Ensure pump supply voltage.
•
Ensure pump speed parameter settings
are set properly.
•
Check the wiring harness to the pump
and PCB for damaged and/or loose
connections.
•
Ensure air is removed from the
recirculation line.
Water Flow Servo
65
•
Measure the resistance values and
voltage of the water flow control.*
•
Ensure the harness and connector are
not wet.
•
If the voltage from the PC Board is
abnormal, replace the PC Board;
otherwise, replace the water flow servo
valve.
50
* See "Electrical Diagnostics" on Technical Data
Sheet located on inside front cover of water heater.
Rinnai Tankless Water Heater Installation and Operation Manual
Bypass Flow Servo
66
•
Measure the resistance values and
voltage of the bypass servo valve.*
•
Ensure the harness and connector are
not wet.
•
If the voltage from the PC Board is
abnormal, replace the PC Board;
otherwise, replace the bypass servo
valve.
PC Board
70
•
Check the connection harness at the
connection on the PC board.
•
Replace PC board.
Solenoid Valve Circuit
71
•
Ensure dip switch on PC board is in the
OFF position.
•
Check gas solenoid valves for short
circuits or grounding.
•
Ensure heater circuit is not grounded.
•
Replace PC Board.
Flame Sensing Device
72
•
Verify flame rod is touching flame when
unit fires.
•
Check the flame rod and wire for
damage.
•
Remove flame rod;check for carbon
build-up; clean with sand paper.
•
Check inside burner chamber for any
foreign material blocking flame at flame
rod.
•
Check the resistance to the cabinet.
•
If there is no issue with the flame rod or
wiring, replace the PC Board
Water Leak Detected
79
•
Turn off water supply and contact
licensed professional.
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