Thermistor - Navien NPE-180A Service Manual

4.11.3 Thermistor

Part
Function
Failure Event
Effects
Error Code
Diagnostic
Color/Number
of wires
Wire Color: BLUE-BLUE
Temp(°F)
32~40
40~50
50~60
60~70
70~80
80~90
90~100
100~110
60 NPE Service Manual
Measure inlet, outlet, and internal heat exchanger temperatures in the water heater.
Unable to properly measure water temperature within the water heater.
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.
E047, E407, E421, E432, E441
1. Visual inspection: Connection and/or breakage of wires.
2. Check the resistance of the sensor (Stop operating and lower the temperature before checking).
Resistance range : Please refer to the table below
Inlet, Outlet
Check Point
Exhaust Limit Temperature Sensor
Wire Color: BLUE-BLUE
Thermistor (kΩ)
17.9~25.4
14.5~20.3
11.4~16.4
9.4~12.8
7.5~10.4
6~8.2
5.1~6.6
4.1~5.7
Exhaust Limit Temperature Sensor (kΩ)
113.6~180.7
89.2~139.5
67.5~108.5
51.5~81.1
41.5~61.3
32.2~48.9
26.3~37.6
20.8~30.4
Version 2.21