What to Do When Your Heater Won’t Turn Off!

It’s not unheard of for heating systems to have a glitch every now and then. It could be as simple as a bad thermostat or an electrical problem. If your gas furnace won’t shut off, here are a few steps you can take to get a properly 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, forcing your furnace to work harder and run longer to satisfy your desired temperature.

This multiplies wear and tear on your furnace, as well as the odds of a malfunction and premature 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 more quickly, it can drive up your heating bill and make your home feel uncomfortable.

We recommend 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, 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 connected to a clogged air filter, replacing it with a clean filter should fix this common issue when your heat won’t turn off. If not, we suggest checking your thermostat settings next.

Check Out the Thermostat

Your thermostat runs your furnace and basically tells the unit when to turn on and off. It’s usually the problem when your furnace won’t stop running.

At times having the heat turn off is as simple as changing a wrong thermostat setting.

Ensure Your Thermostat is Set to “Auto”

Your thermostat has two settings, “auto” and “on,” that control your heating system’s blower motor.

“Auto” means the furnace blower will only operate when the furnace does.

“On” indicates the furnace blower will run constantly. This constant air flow can help with heat circulation 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 sound like your furnace is not turning off, but it’s really just the furnace blower you’re noticing. 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, check the temperature setting to the room temperature. If it’s higher than the room air temp, your furnace will keep running 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 because of a big 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 in a few minutes.

Put in New Batteries

If you have a programmable thermostat, it’s probably battery powered. You can try putting in new batteries to see if that solves the issue. If it doesn’t or if there’s wiring to your electrical system, shift 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 turn off? There are two places you can cut the power to your heating unit: at the breaker box and at its specific power switch.

    1. Head to your breaker box and find the breaker labeled “furnace.” Move the breaker switch to the right to shut off power.
    1. Next, search for the specific power switch to your heating system. It’s similar to a light switch and is located on or near your furnace. Move the switch down to shut off power.
    1. Your furnace should be shut off now.

If you had to switch off your system at the breaker, call us at for professional service, as you may need furnace repair.

What Causes a Furnace to Keep Running?

Occasionally fixing this problem can be as simple as replacing your air filter or adjusting thermostat settings. In other instances, you might want 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 out, 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 a problem with the limit switch. Your furnace will communicate through a blinking red light on the front of your heating system.

Our Experts can identify and fix any issues you’re having with your furnace blower motor. Often this can involve replacement parts, like the control board, faulty wiring or the fan switch itself.

Faulty Thermostat

Like anything else in your home, your thermostat can break down over time and need to be replaced. If you’re due for a new one, ask us about getting a smart thermostat.

These thermostats make it simple to save energy, because they create an energy-efficient heating and cooling schedule according to your needs. Additionally, you’ll be able to set and monitor your thermostat from just about anywhere with your phone.

Leaky Air Ducts

Your furnace uses ductwork to distribute 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.

Identifying this leaky ductwork and other airflow issues can be tricky to troubleshoot on your own, since it’s concealed 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 annoying, 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 rely 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.* Contact us at to schedule your appointment today.

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