Navien NCB-24LSWE, Service Manual

Page: 91 / 144

NCB Service Manual 89 Version 1.0
Error 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 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
Loose screws
Tighten the ground connection screws on the heat exchanger.
PCB fault
If the error condition continues after checking these items, replace the PCB.