It's not uncommon for heating systems to have a glitch every now and then. It could be as straightforward as a broken 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.
Check the Air Filter
A dirty air filter causes problems for numerous homeowners and their HVAC system. Here's why. It restricts airflow, forcing your furnace to work harder and run longer to satisfy your ideal 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 off. Then it will keep repeating this process when your furnace switches 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 uncomfortable.
We encourage replacing flat filters once a 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 detect light through your filter, it's too dusty and you should get a new one.
If the matter was connected to a clogged air filter, putting in a new filter should fix this common problem when your heat won't turn off. If not, we recommend checking your thermostat settings next.
Check the Thermostat
Your thermostat runs your furnace and basically tells the unit when to turn on and off. It's often the problem when your furnace won't stop running.
At times having the heat turn off is as easy as changing an incorrect thermostat setting.
Make Sure Your Thermostat is Set to “Auto”
Your thermostat includes two settings, “auto” and “on,” that control your heating system's blower motor.
“Auto” indicates the furnace blower will only run 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 switched to "on," it will seem like your furnace is not turning off, but it's really just the furnace blower you're noticing. Switching it to "auto" should solve 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, check 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.
Keep in mind that if it's extremely cold outside, your furnace will have to run 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 check, you can try reducing the setting to correspond with the room. Then, wait a few minutes. This should make the furnace shut off in a few minutes.
Replace the Batteries
If you have a programmable thermostat, it's probably 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 shut off after you move it to "off," you will need to turn off the power.
Cut the Power
Thermostat seems to be working fine but your furnace still won't turn off? There are two spots you can shut off 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." 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 turn off your system at the breaker, call us at 623-243-4517 for professional service, as you may need furnace repair.
What Causes a Furnace to Keep Running?
Occasionally fixing this problem can be as easy as changing your air filter or adjusting thermostat settings. In other situations, you might need a professional when your heater won't shut off.
Fan Limit Switch Needs to Be Replaced
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 an issue with the limit switch. Your furnace will speak via a flashing red light on the front of your heating system.
Our Experts can identify and correct 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 you're due 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 according to your preferences. Plus, you'll be able to set and keep tabs on your thermostat from just about anywhere with your phone.
Leaky Air Ducts
Your furnace uses ductwork to circulate hot air to vents throughout your home. If your home or ductwork is older, your furnace might be running constantly since the ductwork is leaking hot air in the attic.
Diagnosing this leaky ductwork and other airflow problems can be difficult to troubleshoot 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 comes to furnaces, there's a reason why we say we're Experts in our industry. You can depend on our ACE-certified technicians to resolve your problem quickly and affordably. And what's even better, we back our HVAC system repairs with a 100% satisfaction guarantee for one year.* Call us at 623-243-4517 to schedule your appointment today.