Navien NP-180, Service Manual

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4.6.2. Thermal Fuse
Navien Part No.
Failure Event
Function
1. Unable to detect the excessively high temperature within the unit
1. It protects over limited high temperature in burner due to abnormal operations.
2. The thermal fuse contains solder with a melting point of 383
ȕ (195 Ȕ ).
3. Detects excessive temperature within the unit, especially around the
heat exchanger and combustion chamber. Upon detection, communication
between the PCB and gas valves will sever, shutting down the unit instantly.
1. Flames from burner may penetrate a ruptured/damaged heat exchanger.
2. The water heater is not operating.
N/A
1. Visual inspection: Connection and/or breakage of wires.
2. Voltage check: Check range of voltage shown below.
Black - Black
Effects
Error Code
Diagnostic
BH1419012A
BH1419013A
Check Point N/A
Color /
Number of wires