It's not uncommon for heating systems to have a problem once in a while. It could be as straightforward as a bad thermostat or an electrical problem. If your gas furnace won't turn off, here are a couple steps you can take to get a properly working furnace again.
Check the Air Filter
A dirty air filter creates issues for many homeowners and their HVAC system. Here's why. It restricts airflow, making your furnace work harder and run longer to satisfy your desired temperature.
This multiplies usage on your furnace, as well as the likelihood of a breakdown and premature failure.
It can also make your furnace get too hot and shut down for a time to cool down. Then it will keep repeating this process when your furnace turns on. This is called short cycling. In addition to wearing out your furnace more quickly, it can increase your heating bill and make your home feel unpleasant.
We encourage replacing flat filters monthly and pleated filters every three months. If you can't remember the last time you got a new furnace filter, pull it out and hold it up to the light. If you can't see light through your filter, it's too dusty and you should get a new one.
If the matter was linked to a clogged air filter, replacing it with a fresh filter should fix this common problem when your heat won't turn off. If not, we suggest checking your thermostat settings next.
Check the Thermostat
Your thermostat controls your furnace and simply informs the unit when to turn on and off. It's often to blame when your furnace won't stop running.
Sometimes having the heat turn off is as easy as changing a wrong thermostat setting.
Make Sure Your Thermostat is Set to “Auto”
Your thermostat includes two settings, “auto” and “on,” that manage your heating system's blower motor.
“Auto” means the furnace blower will only operate when the furnace does.
“On” means the furnace blower will operate continuously. This constant air flow can help with heat distribution but will also increase your power bill and lead to wear and tear on your furnace.
If your thermostat is set to "on," it will seem like your furnace is not turning off, but it's really just the furnace blower you're hearing. Changing it to "auto" should resolve the problem. It will also help you save money on your energy costs.
Confirm Your Temperature Setting
If your thermostat won't turn off heat, check the temperature setting to the area temperature. If it's greater than the room air temp, your furnace will keep operating until it reaches your desired temp.
Keep in mind that if it's very cold outside, your furnace will have to run much longer than usual to keep your home warm. This is due to a big temperature difference between the cold air outside and the warm indoors.
As a check, you can try reducing the setting to correspond with the room. Then, wait a couple of minutes. This should make the furnace turn off momentarily.
Put in New Batteries
If you have a programmable thermostat, it's likely battery powered. You can try putting in new batteries to see if that resolves the issue. If it doesn't or if there's wiring to your electrical system, switch it to "off."
If your furnace won't shut off after you set it to "off," you will need to cut the power.
Turn Off the Power
Thermostat appears to be working fine but your furnace still won't shut off? There are two spots you can cut the power to your heating unit: at the breaker box and at its specific power switch.
- Go to your breaker box and find the breaker labeled "furnace." Push the breaker switch to the right to cut power.
- Next, look for the dedicated power switch to your heating system. It's similar to a light switch and can be found on or close to your furnace. Push the switch down to cut power.
- Your furnace should be shut off now.
If you had to turn off your system at the breaker, call us at 630-246-2698 for professional service, as you may require furnace repair.
What Causes a Furnace to Keep Running?
Occasionally correcting this problem can be as easy as replacing your air filter or adjusting thermostat settings. In other instances, you might need a professional when your heater won't turn off.
Fan Limit Switch Needs Replacing
The furnace fan limit switch controls your furnace's blower motor. If the switch goes bad, it might sound like your furnace running continuously, even though just the blower is going.
You might notice a furnace error code if there's an issue with the limit switch. Your furnace will communicate using a flashing red light on the front of your heating system.
Our Experts can identify and fix any problems you're having with your furnace blower motor. Sometimes this can involve replacement parts, like the control board, faulty wiring or the fan switch itself.
Like anything else in your home, your thermostat can wear out as time passes and need to be replaced. If it's time for a new one, ask us about installing a smart thermostat.
These thermostats make it easy to save energy, since they develop an energy-efficient heating and cooling schedule according to your needs. Additionally, you'll be able to set and keep tabs on your thermostat from just about anywhere with your phone.
Air Ducts Are Leaking
Your furnace relies on ductwork to circulate hot air to vents throughout your home. If your home or ductwork is older, your furnace might be operating constantly because the ductwork is leaking hot air in the attic.
Diagnosing this leaky ductwork and other airflow issues can be difficult to troubleshoot on your own, since it's concealed behind walls and ceilings. Our Experts can help with diagnosing and handling any air duct repair service that you require.
Rely on Our Experts for All Your Furnace Repair Needs
Troubleshooting furnace issues can be inconvenient, particularly when it impacts your comfort, energy efficiency and heating bill. When it involves furnaces, there's a reason why we say we're Experts in our field. You can count on our ACE-certified technicians to resolve your problem quickly and affordably. And what's even better, we stand behind our HVAC system repairs with a 100% satisfaction guarantee for one year.* Contact us at 630-246-2698 to book your appointment now.