Navien NFC-175 Service Manual page 83

Fault
Flame loss and noise
occurs after ignition
Flame loss during
2nd stage
Other trouble
Version 1.0
Possible Causes
Digital pressure
manometer
Check the offset values for Min fire
Model
NFC-175
NFC-200
Replace the electrode or clean the fire detecting electrode.
- Cause: Due to the properties of the electrode, the oxide film is created due to
- Check-up: Use sandpaper to clean the fire detecting electrode covered with
Flame Rod
(Electrode)
1. Check the presence of debris in the metal fiber.
Defected metal fiber
2. Check the sagging of the metal fiber and then the gaps with the electrode.
[Gap between the electrode and metal fiber: 12mm]
Flame loss will occur if the gas orifices in the Dual Venturi are clogged.
Blockage in the gas
Remove the gas inlet pipe and check for debris inside the Dual Venturi; remove
●
orifice plate.
and clean the orifice plate if necessary.
Defective PCB If the issue continues despite checking above items, replace the PCB.
Check method
Model
NFC-175
NFC-200
Altitude Fuel
NG
0-5,399 ft
LP
NG
5,400-10,100 ft
LP
CO value
2
long-term exposure to the high temperature; therefore, errors may be caused
in detecting the fires.
oxide film or replace it.
Gas
Altitude Kit Part No.
Type
0-5,399 ft NAC-N200
NG
5,400-
NAC-NCH200
10,100 ft
0-10,100 ft NAC-LC200
Offset value for low fire
High fire Low fire
%CO %CO
2 2
8.9 9.5
10.2 10.8
8.5 9.5
10.2 10.8
NFC Service Manual
Offset
-0.04 in
±0.01 in
-0.02 in
LP
±0.01 in
83