Navien NCB300-28K, Service Manual

Page: 64 / 108

Troubleshooting 63
Error type Cause Testing method
Repeated
ignition failure
Flame error
1. Inspect the flame area for deformation or foreign deposit. Repair or replace the
part.
2. Check that the flame rod wiring connections are secure and free from damage.
3. Check the boiler case grounding connection is connected and secure.
●
If the ground wire is not adequately connected, remove and reattach the
ground wire to ensure there is good contact with the case.
●
Use a multimeter to test the spark current (normally 3-4 µA).
Test the spark current connectors Ground connection
Flame loss and
noise occurs at
ignition
Check for obstructions in
the gas orifice plate.
Ignition failure can occur if the gas orifice is obstructed.
●
Remove the gas inlet pipe and check the orifice plate.
Improper air
intake air supply
Rainwater ingress
Check if rainwater has accumulated inside the unit boiler through an incorrectly
installed air intake pipe.
Other faults PCB fault If the error condition continues after checking these items, replace the PCB.