Component
Gas valve
The gas valve admits gas to the burners only when the control commands it after ignition conditions are met. Gas-valve faults are serious by nature: diagnosis checks that the valve opens when commanded, closes when not, and delivers the right pressure, and any work on it is licensed-gas-fitter work.
Smell gas?
- Do not operate light switches, appliances or phones inside.
- Leave the building and leave the door open behind you.
- From outside, call the FortisBC emergency line at 1-800-663-9911 or 911.
- Only after that, call BC Wide about the furnace.
A furnace that will not run is a breakdown, not a gas emergency. Gas smell, a CO alarm, soot or scorching are.
Short answer
If the furnace is not lighting and the ignitor glows but no gas flows, the gas valve may not be opening, or gas may not be reaching it: check the shut-off valve position first. Testing a gas valve involves measuring voltage at its terminals during the trial and checking pressures; that is licensed-gas-fitter work, and a valve that leaks or fails closed is replaced, not repaired.
How the valve works
The gas valve is electrically controlled and pressure regulated. The control energizes it only after draft is proven and the ignitor is hot; the valve opens, gas flows to the burners, and the flame sensor confirms ignition. Redundant valves contain multiple safety shutoffs by design.
Failure modes
A valve can fail to open (no gas, ignition codes), fail to close (gas flow with the furnace off, a serious condition some controls detect as false flame or as voltage where none should be), or regulate badly (wrong pressures, sooty or noisy burners). Failures are diagnosed by measuring the control's output, the valve's response and the pressures.
The rules around gas valves
Gas valves are not repaired in the field; they are replaced with the manufacturer's part. Pressure adjustments inside the valve follow the manufacturer's procedure and are gas-fitter work. If you ever smell gas, leave the building and call FortisBC at 1-800-663-9911 or 911 before anything else.
Related
- ServiceGas Furnace RepairFurnace repair in Greater Vancouver, diagnosed before parts are replaced
- ServiceEmergency Furnace RepairNo heat tonight? Call and speak to a person.
- ServiceFurnace DiagnosticsFind the actual fault before replacing parts: diagnosis by testing, not guessing
- SymptomFurnace not heating
- SymptomFurnace blowing cold air
Questions people ask
Is a gas valve failure an emergency?
A furnace that will not light because the valve will not open is a breakdown, not an emergency. A valve that lets gas flow when the furnace is off is an emergency: if you smell gas, leave and call FortisBC at 1-800-663-9911 or 911.
Can a gas valve be adjusted to fix a noisy burner?
Burner noise can come from pressure, orifices or burner condition. Adjusting valve pressure is gas-fitter work done with instruments, and only within the manufacturer's procedure.
Why does my furnace have two gas-valve codes?
Some controls detect 24 V at the valve circuit when it should not be there, or a valve relay that will not close. Both are documented on this site's code pages for the controls that show them.
Need this looked at?
Call BC Wide with the brand, model number and anything on the display. Or
Request service online with this page attached.