Circuit Breaker Operation - Navien NCB300-28K Service Manual

5.3.3 Circuit breaker operation

Error type
Defective sensor
Circuit breaker trips
Remote controller power
84 Troubleshooting
Cause
The circuit breaker trips immediately as soon as the power cord is plugged in
the receptacle.
Power supply
Check the sheath of power cord, or if there is short-circuit.
Check the components in order from the power transformer to the PCB.
If the circuit breaker operates after repairs check the wiring of each part.
Maintain proper direction when assembling the ignition transformer.
Defective part assembly Be careful that wire is not compressed when assembling the main gas valve
Check if the wire is fixed and properly attached on the main side of the heat
exchanger.
Short-circuit due to defective assembly
If circuit breaker trips during the operation of the boiler, check the order of
Circuit breaker operates
operation, and replace the concerned part.
while the boiler is
e.g., The circuit breaker operates at switchover to burner stage 2 after ignition.
running
●
Check the power supply to the remote controller terminal.
If there is a problem in power supply, check the output voltage of the PCB,
Check the wire
and take the action separately for wiring error and defective PCB, respectively.
If the power supply is normal, replace the remote controller.
Normal assembly
Replace the dual venturi.
Check method
Wiring near the heat exchanger