Navien NCB300-28K Service Manual page 64

Error type
Flame error
Repeated
ignition failure
Flame loss and
Check for obstructions in
noise occurs at
the gas orifice plate.
ignition
Improper air
Rainwater ingress
intake air supply
Other faults PCB fault
Cause
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
Ignition failure can occur if the gas orifice is obstructed.
Remove the gas inlet pipe and check the orifice plate.
●
Check if rainwater has accumulated inside the unit boiler through an incorrectly
installed air intake pipe.
If the error condition continues after checking these items, replace the PCB.
Testing method
Ground connection
Troubleshooting 63