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 shut off, here are a few steps you can take to get a correctly working furnace again.
Examine the Air Filter
A dirty air filter causes problems for many homeowners and their HVAC system. Here's why. It limits airflow, making your furnace work harder and run longer to meet your desired temperature.
This multiplies usage on your furnace, as well as the likelihood of a malfunction and early failure.
It can also make your furnace overheat and shut down for a time to cool down. 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 encourage replacing flat filters each month 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 dirty 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 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 basically tells 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 changing an incorrect thermostat setting.
Make Sure Your Thermostat is Set to “Auto”
Your thermostat has 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 constantly. This constant air flow can help with heat circulation but will also drive up your power bill and increase wear and tear on your furnace.
If your thermostat is set to "on," it will seem like your furnace is not shutting 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.
Check Your Temperature Setting
If your thermostat won't turn off heat, compare the temperature setting to the area temperature. If it's higher than the room air temp, your furnace will keep operating until it hits your desired temp.
Keep in mind that if it's very cold outside, your furnace will have to operate much longer than usual to keep your home cozy. This is due to a large temperature difference between the cold air outside and the warm indoors.
As a check, you can try decreasing the setting to match 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 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 move it to "off," you will need to cut the power.
Cut the Power
Thermostat seems to be working fine but your furnace still won't shut off? There are two spots 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 marked "furnace." Push the breaker switch to the right to shut off power.
- Next, look for the dedicated power switch to your heating system. It's similar to a light switch and is located on or close to your furnace. Push the switch down to shut off power.
- Your furnace should be shut off now.
If you had to switch off your system at the breaker, call us at 587-315-5271 for professional service, as you may require furnace repair.
What Causes a Furnace to Keep Running?
Occasionally fixing this problem can be as simple as replacing your air filter or changing thermostat settings. In other situations, you might need a professional when your heater won't turn off.
Fan Limit Switch Needs Replacing
The furnace fan limit switch regulates your furnace's blower motor. If the switch goes out, it might sound like your furnace running nonstop, even though just the blower is going.
You might see a furnace error code if there's a problem with the limit switch. Your furnace will speak through a blinking 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. Often this can involve replacement parts, such as the control board, faulty wiring or the fan switch itself.
Defective Thermostat
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 create an energy-efficient heating and cooling schedule based on your preferences. Additionally, you'll be able to adjust and monitor your thermostat from just about anywhere 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 operating constantly because the ductwork is leaking hot air in the attic.
Diagnosing this leaky ductwork and other airflow issues can be tricky to resolve 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 need.
Depend on Our Experts for All Your Furnace Repair Needs
Troubleshooting furnace issues can be annoying, particularly 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 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.* Call us at 587-315-5271 to book your appointment today.