It's not unheard of for heating systems to have a glitch every now and then. It could be as straightforward as a bad thermostat or an electrical issue. If your gas furnace won't turn off, here are a few steps you can take to get a properly working furnace again.
Examine the Air Filter
A dirty air filter creates issues for numerous homeowners and their HVAC system. Here's why. It limits airflow, forcing your furnace to work harder and run longer to satisfy your desired temperature.
This multiplies usage on your furnace, as well as the odds of a breakdown and early failure.
It can also make your furnace overheat and shut off for a time to cool down. Then it will keep duplicating this process when your furnace turns on. This is called short cycling. In addition to wearing out your furnace faster, it can increase your heating bill and make your home feel uncomfortable.
We recommend replacing flat filters monthly and pleated filters every three months. If you can't remember the last time you replaced your furnace filter, remove it and hold it up to the light. If you can't detect light through your filter, it's too dirty and you should get a new one.
If the matter was connected to a clogged air filter, replacing it with a clean 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.
At times having the heat turn off is as easy as adjusting an incorrect thermostat setting.
Ensure 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 run when the furnace does.
“On” indicates the furnace blower will run continuously. This constant air flow can help with heat circulation but will also drive up your power bill and lead to wear and tear on your furnace.
If your thermostat is switched to "on," it will sound like your furnace is not shutting 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 spend less money on your energy costs.
Confirm Your Temperature Setting
If your thermostat won't turn off heat, compare the temperature setting to the area temperature. If it's greater than the room air temp, your furnace will keep running until it hits your desired temp.
Remember that if it's extremely cold outside, your furnace will have to operate much longer than normal to keep your home warm. This is due to a large temperature difference between the cold air outside and the warm indoors.
As a test, you can try reducing the setting to match the room. Then, wait a couple of minutes. This should make the furnace turn off momentarily.
Put in Fresh Batteries
If you have a programmable thermostat, it's probably battery powered. You can test putting in new batteries to see if that solves 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 turn off the power.
Cut the Power
Thermostat appears to be working fine but your furnace still won't shut off? There are two places you can shut off the power to your heating unit: at the breaker box and at its dedicated power switch.
- Head to your breaker box and find the breaker labeled "furnace." Move the breaker switch to the right to shut off power.
- Next, look for the specific power switch to your heating system. It looks like a light switch and is located on or near your furnace. Push the switch down to shut off power.
- Your furnace should be turned off now.
If you had to switch off your system at the breaker, contact us at 210-570-9705 for professional service, as you may require furnace repair.
What Causes a Furnace to Keep Running?
Sometimes fixing this problem can be as easy as changing your air filter or changing thermostat settings. In other situations, you might need a professional when your heater won't shut off.
Fan Limit Switch Needs Replacing
The furnace fan limit switch controls your furnace's blower motor. If the switch goes out, it might sound like your furnace running continuously, even though just the blower is running.
You might notice a furnace error code if there's an issue with the limit switch. Your furnace will communicate via a flashing red light on the front of your heating system.
Our Experts can diagnose 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 other things in your home, your thermostat can break down as time passes and need to be replaced. If you're due 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 adjust and monitor your thermostat from just about anyplace with your phone.
Air Ducts Are Leaking
Your furnace relies on ductwork to distribute hot air to vents throughout your home. If your home or ductwork is older, your furnace might be running all the time since the ductwork is leaking hot air in the attic.
Identifying this leaky ductwork and other airflow problems can be challenging to troubleshoot on your own, since it's hidden behind walls and ceilings. Our Experts can help with diagnosing and taking care of any air duct repair service that you require.
Depend on Our Experts for All Your Furnace Repair Needs
Troubleshooting furnace issues can be inconvenient, especially 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 industry. You can rely on our ACE-certified technicians to solve your problem quickly and affordably. And what's even better, we back our HVAC system repairs with a 100% satisfaction guarantee for one year.* Contact us at 210-570-9705 to book your appointment today.