Navien NCB-24LSWE, Service Manual

Page: 95 / 144

NCB Service Manual 93 Version 1.0
Fault Possible causes Testing method
Flame loss and
noise occurs
after ignition
Flame loss
during Stage 2
Blockage in the
gas orifice plate.
Flame loss will occur if the gas orifices in the dual venturi are clogged.

Remove the gas inlet pipe and check for debris inside the dual venturi. Remove
and clean the orifice plate if necessary.
Other faults
PCB DIP switch
setting errors
Check the PCB DIP switch settings (refer to page 20).
PCB fault If the error conditions continue after checking these items, replace the PCB.