Troubleshooting Your Gas Furnace
Gas Furnace Troubleshooting
The most common problems with a gas furnace that you can evaluate are:
Furnace doesn't turn on
- Check that the thermostat is set correctly to “heat.” The mode could be off or set on cooling, or the set point might be higher than the indoor temperature, causing the furnace to turn off until additional heat is required. Try adjusting the temperature on the thermostat to be higher than the current room temperature.
- Check the thermostat to ensure it is getting power. Those that aren’t hardwired into your home use batteries that may need to be replaced.
- Check that the fan switch is turned to the “on” or “auto” setting.
- Check the circuit breaker to ensure the furnace is still getting power.
- Check the pilot light if you are using an older furnace. If the pilot has gone out, relight it carefully.
- Check to ensure that the gas supply is still on. However, if you suspect a gas leak or smell gas in your home, do not turn any switches on or off, and do not attempt to relight the pilot light. Call the gas company to come check it.
Air is not hot enough
- Check the air filter. A clogged filter limits the amount of air that gets through.
Furnace turns off and on constantly
- Check the thermostat setting.
- Check the air filter.
- Check to ensure room air vents are open and objects are not covering them.
Furnace runs noisily
- Whistling sound—check the air filter to see if it is clogged.
- A loud ignition sound when starting up the furnace—check the burner. A clogged burner can delay ignition, which causes a loud noise when the gas ignites. This repair requires an expert.
- Whistling or rattling—check for loose connections in the ductwork that can rattle as air flows through.
When to Call an Expert
Every homeowner has a different comfort level working with gas furnaces. The time to call an expert is when you’re uncomfortable performing any of this troubleshooting yourself. Trained experts can help resolve your heating issues quickly and easily.