Furnace part
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.
The control energizes the gas valve only after draft is proven and the ignitor is hot. Redundant valves contain multiple safety shutoffs by design, and the valve also regulates gas pressure to the burners.
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 licensed-gas-fitter work.
Safety
If you smell gas, leave the building and call FortisBC at 1-800-663-9911 or 911 before anything else. All work on the gas valve and its supply is licensed-gas-fitter work under permit.
Signs this part is involved
- Ignitor glows but no gas flows and the furnace will not light
- Codes reporting voltage sensed on the valve circuit when it should not be
- False-flame codes (the control sees flame when the valve should be closed)
- Wrong gas pressures producing noisy or sooty burners
Related fault codes
- Carrier 59TP6C status code 21.1: 24 VAC sensed on the gas valve when it shouldn't be
- Carrier 59TP6C status code 22.1: false flame
- Carrier 59TP6C status code 45: control failure
- Carrier 59SC6A status code 21.1: 24 VAC sensed on the gas valve when it shouldn't be
Codes are documented per controller; check the model number on your rating plate before comparing. Not sure which control you have?
Related
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: leave the building 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, only within the manufacturer's procedure.
Not sure whether the gas valve is your problem?
BC Wide diagnoses by testing, not by part swapping. Tell us the model number from the rating plate and what the furnace is doing.