It's not uncommon for heating systems to have a glitch every now and then. It could be as straightforward as a bad thermostat or an electrical problem. If your gas furnace won't turn off, here are a few steps you can take to get a correctly working furnace again.
Check the Air Filter
A dirty air filter causes problems for numerous homeowners and their HVAC system. Here's why. It limits airflow, making your furnace work harder and run longer to satisfy your ideal temperature.
This multiplies usage on your furnace, as well as the likelihood of a breakdown and early failure.
It can also make your furnace overheat and shut down for a time to cool off. Then it will keep repeating this process when your furnace turns on. This is known as short cycling. In addition to wearing out your furnace faster, it can drive up your heating bill and make your home feel unpleasant.
We recommend replacing flat filters each month 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 see light through your filter, it's too dirty and you should get a new one.
If the matter was linked to a clogged air filter, replacing it with a new filter should fix this common issue when your heat won't turn off. If not, we suggest checking your thermostat settings next.
Check the Thermostat
Your thermostat runs your furnace and simply informs the unit when to turn on and off. It's often the problem when your furnace won't stop running.
Sometimes 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 operate when the furnace does.
“On” means the furnace blower will run continuously. This constant air flow can help with heat distribution but will also increase your power bill and increase wear and tear on your furnace.
If your thermostat is set to "on," it will sound like your furnace is not turning off, but it's really just the furnace blower you're hearing. Changing it to "auto" should solve 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 higher than the room air temp, your furnace will keep running until it reaches your desired temp.
Remember that if it's extremely cold outside, your furnace will have to operate much longer than usual to keep your home cozy. This is because of a large temperature difference between the cold air outside and the warm indoors.
As a test, you can try decreasing the setting to correspond with the room. Then, wait a couple of minutes. This should make the furnace turn off in a few minutes.
Replace the Batteries
If you use a programmable thermostat, it's likely battery powered. You can test 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 turn off after you move 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 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, search for the specific power switch to your heating system. It looks like a light switch and can be found on or near your furnace. Push the switch down to cut power.
- Your furnace should be turned off now.
If you had to turn off your system at the breaker, call us at 352-414-4006 for professional service, as you may need furnace repair.
What Causes a Furnace to Keep Running?
Occasionally correcting this problem can be as simple as changing your air filter or changing thermostat settings. In other instances, 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 bad, it might seem like your furnace running continuously, even though just the blower is running.
You might see a furnace error code if there's a problem with the limit switch. Your furnace will communicate through 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, such as the control board, faulty wiring or the fan switch itself.
Defective Thermostat
Like other things in your home, your thermostat can wear out over time and need to be replaced. If it's time for a new one, ask us about installing a smart thermostat.
These thermostats make it simple to save energy, because they create an energy-efficient heating and cooling schedule based on your preferences. Plus, you'll be able to adjust and keep tabs on your thermostat from just about anyplace with your phone.
Leaky Air Ducts
Your furnace relies on ductwork to circulate hot air to vents across your home. If your home or ductwork is older, your furnace might be running constantly because the ductwork is leaking hot air in the attic.
Diagnosing this leaky ductwork and other airflow problems can be tricky to resolve on your own, since it's hidden behind walls and ceilings. Our Experts can help with identifying and taking care of any air duct repair service that you need.
Rely on Our Experts for All Your Furnace Repair Needs
Troubleshooting furnace problems 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 stand behind our HVAC system repairs with a 100% satisfaction guarantee for one year.* Call us at 352-414-4006 to book your appointment today.