Navien NCB-700-2S+/42K Service Manual page 73

Error type
Repeated
ignition failure
Flame loss and
Check for obstructions in
noise occurs at
ignition
Improper air
intake air supply
Other faults
72 Troubleshooting
Cause
1. Inspect the flame area for deformation or foreign deposit. Repair or replace the
2. Check that the flame rod wiring connections are secure and free from damage.
Flame error
3. Check the boiler case grounding connection is connected and secure.
Test the spark current connectors
Ignition failure can occur if the gas orifice is obstructed.
the gas orifice plate.
Remove the gas inlet pipe and check the orifice plate.
●
Check if rainwater has accumulated inside the unit boiler through an incorrectly
Rainwater ingress
installed air intake pipe.
Tighten the ground connection screws on the heat exchanger.
Loose screws
PCB fault If the error condition continues after checking these items, replace the PCB.
part.
If the ground wire 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).
●
Testing method
Ground connection