004Error - Navien NFC-175 Service Manual

5.2.3 004Error

Error occurrence conditions and check items
Error
E004
False-flame detection
Check items
Check method
Failure mode
Flame before / after
combustion
Error before / after
combustion
Other trouble
80 NFC Service Manual
1. Pre ignition false-flame
If a flame signal is detected continuously for 3 seconds before combustion (stand-by, pre-
purge, pre-ignition), a false-flame error 004E (automatically cleared) is displayed on the
front panel and the system performs continuous post-purge and operates the pump.
2. Post purge false-flame
If a flame signal is detected continuously for 3 seconds when the system performs post-
purge as fuel supply is stopped, a false-flame error 004E (automatically cleared) is displayed
on the front panel and the system performs continuous post-purge and operates the
pump.
1. Check if gas leaks due to defective seals on the main gas valve.
2. Check if proper spark is discharged from the electrode.
3. Check if gas is supplied within the proper pressure range.
4. Check the PCB and replace if defective.
Is the flame detected in
the burner when there is
no ignition?
Yes
External noise current
Cause
Leakage from main gas Replace the gas valve if flame occurs before combustion or if there is remaining
valve flame after combustion is stopped.
Spark discharges from electrode to flame sensor at ignition.
Discharge of electricity
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" W.C, LP: 8" - 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.
Description
No
Clean or replace flame rod
Check the current #2 of CNI1: Over 3-4 μA
(See page 50-51 for Wiring Diagram.)
Check method
Version 1.0