Navien NCB-150E Service Manual page 97

Check method
Failure mode
Flame before/after Leakage from main gas
combustion
Discharge of electricity
Error before/after
combustion
Other trouble
96 NCB-E Service Manual
Cause
Replace the gas flame if flame occurs before combustion or if there is remaining flame
valve after combustion is stopped.
Spark discharges from electrode to flame sensor at ignition.
from electrode
Replace or correct location of flame detecting rod.
●
Gas may leak as the main gas valve is pushed by the gas supply over the standard
pressure.
Check the supply pressure: NG: 3.5" - 10.5" WC, LP: 8.0" - 13.5"W.C
●
Gas valve
If the gas pressure is too high, notify the gas supplier about the issue, and if
●
necessary, replace the gas valve.
If there is a gas leak close the gas supply valve and repair the unit before using the
●
system.
Defective PCB If the issue continues despite the checking of items above, replace the PCB.
Check method
Version 1.4