Navien NHB-055 Service Manual page 86

Scenario2
Is gas valve operating
normally?
Yes
Check the flame rod
Scenario3
Is the flame detection
device normally operating?
Yes
Restart unit
Access the Service Information Display to check
Item (K) for Flame State (see Page 41-42)
86 NHB Service Manual
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 CN19)
No
Check connector
Check the voltage between the WHITE-YELLOW of
CN 16: 22-24 VDC
Check the voltage between the WHITE-RED wires of
CON 4: 22-24 VDC
No
Check that gas valve is open or
check LP supply
In case of LP gas model, low gas pressure can cause
"Ignition Failure".
* Normal gas pressure: 8.0 - 13.5" w. c.
Clean or replace the flame rod
No
Check whether ground circuit is
properly installed.
Check the current #1 of CN 19: DC 1 - 20μA
(see page 63-64 for Wiring Diagram)
Version 1.0