The Noritz gas valve is a modulating solenoid assembly that controls gas flow to the burner. Primary safety device plus the source of Noritz's wide modulation range (15-100% of max BTU).
Why dealer-only
- Requires gas-line work — licensed plumber territory
- Factory-calibrated for NG or LP. Field conversion requires kit and recalibration
- Improper installation creates gas leak hazard
- Warranty voided if non-licensed person performs gas-side work
Symptoms of failure
- Burner won't light — solenoid stuck closed. Code 11
- Burner stuck at full fire — modulating solenoid stuck open
- Burner stuck at low fire — solenoid stuck partially closed
- Burner won't shut off — most serious. Manual shutoff required
Cost
- Parts: $250-500 OEM, model-dependent
- Labor: $300-600
- Total: $550-1,100
Warranty
Inside the 5-year parts warranty, valve is covered. Labor your cost after year 1.
NG to LP conversion
Requires Noritz LP conversion kit + licensed installer to recalibrate. Always done at install, occasionally retroactively if you switch fuel.
Bottom line
Suspect gas valve = call Noritz support immediately. Don't operate the unit if you suspect stuck-open or stuck-on valve.