Main Gas Valve - Navien NCB-700-2S+/42K Service Manual

4.7.8 Main Gas Valve

Item
Function
Fault
Symptoms
Error codes
Diagnostics
Testing/inspection
information
50 System Details
1. Controls the amount of gas supplied to the burner based on fan speed.
2. When the unit experiences abnormal combustion, it automatically shuts off the gas supply to prevent
unsafe situations.
Unable to open / close
1. No flame.
2. The boiler does not operate.
E003, E012
1. Visual inspection: Check wire connections are secure and inspect for wire damage.
2. Check that the solenoid valve of Main Gas Valve works properly.
Voltage test: Test the voltage meets the specifications shown below.
●
WHITE - YELLOW/Connector Pin 1 and 5: DC 24 V
Description