Navien NHB-055, Service Manual

Page: 86 / 147

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