Navien NFC-175 Service Manual page 75

Scenario2
Is gas valve operating
normally?
Yes
Check the flame rod
Scenario3
Is the flame detection
device normally operating?
Yes
Restart unit
Access the Status Information menu to check
Item #14 for Flame State (see page 36).
Version 1.0
No
Does the main gas valve
have proper voltage?
Yes
Is gas valve open?
Yes
Power OFF the unit
No
Is the flame current
detected?
Yes
Check connector
(#1 of CNI1)
No
Check connector
Check the voltage between the RED-YELLOW
(#1 and #2) of CNG1: 22-24 VDC
Check the voltage between the RED-WHITE
(#1 and #3) of CNG1: 22-24 VDC
No
Check that gas valve is open and
check gas supply pressure
Insufficient gas supply pressure can cause "Ignition
Failure".
* Normal gas pressure:
LP=8" – 13.5" W.C; NG=3.5" - 10.5" W.C
Clean or replace the flame rod
No
Check whether ground circuit is
properly installed.
Check the current #2 of CNI1: DC 1 - 20μA
(see page 50-51 for Wiring Diagram)
NFC Service Manual 75