60 NPE Service Manual
4.11.3 Thermistor
Part Check Point
Function Measure inlet, outlet, and internal heat exchanger temperatures in the water heater.
Failure Event Unable to properly measure water temperature within the water heater.
Effects
1. If any of the thermistors fail, an error code appears before starting operation.
2. If resistance values are off, the water heater will produce temperature fluctuations in hot water.
Error Code E047, E407, E421, E432, E441
Diagnostic
1. Visual inspection: Connection and/or breakage of wires.
2. Check the resistance of the sensor (Stop operating and lower the temperature before checking).
Color/Number
of wires
Resistance range : Please refer to the table below
Temp(°F) Thermistor (kΩ) Exhaust Limit Temperature Sensor (kΩ)
32~40 17.9~25.4 113.6~180.7
40~50 14.5~20.3 89.2~139.5
50~60 11.4~16.4 67.5~108.5
60~70 9.4~12.8 51.5~81.1
70~80 7.5~10.4 41.5~61.3
80~90 6~8.2 32.2~48.9
90~100 5.1~6.6 26.3~37.6
100~110 4.1~5.7 20.8~30.4
Wire Color: BLUE-BLUE
Inlet, Outlet
Exhaust Limit Temperature Sensor
Wire Color: BLUE-BLUE
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