Main Gas Valve - Navien NCB-180 Service Manual

4.9.8 Main Gas Valve

Part
Function
Failure Event
Effects
Error Code
Diagnostic
Color/Number of wires
PIN No.
1. To control the amount of gas supplied to the burner based on fan speed.
2. When the unit experiences abnormal combustion, it shuts off the gas valve automatically and
prevents unsafe situations.
Unable to open/close
1. No flames.
2. No operation of the unit.
E003, E012
1. Visual inspection: Connection and/or breakage of wires.
2. Check if the solenoid valve of Main Gas Valve works properly.
Resistance check : Check range of resistance shown below.

Connector Pin No. 1&3 : over 100-1000 Ω

Connector Pin No. 1&4 : over 100-1000 Ω

Resistance range : 100~1,000 Ω
Check Point