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 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 creates problems for numerous homeowners and their HVAC system. Here’s why. It restricts airflow, making your furnace work harder and run longer to satisfy your desired temperature.

This increases 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 known as short cycling. In addition to wearing out your furnace faster, it can increase your heating bill and make your home feel unpleasant.

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 detect light through your filter, it’s too dirty and you should replace it.

If the matter was connected 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 controls 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.

At times having the heat turn off is as simple as changing a wrong 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” indicates 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 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 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.

Check 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 reaches your desired temp.

Remember that if it’s very cold outside, your furnace will have to run much longer than usual 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 decreasing the setting to correspond with the room. Then, wait a few minutes. This should make the furnace turn off in a few minutes.

Replace the Batteries

If you have a programmable thermostat, it’s probably battery powered. You can test replacing the batteries to see if that resolves the problem. 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 switch it to “off,” you will need to cut the power.

Turn Off 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.

    1. Head to your breaker box and locate the breaker marked “furnace.” Push the breaker switch to the right to shut off power.
    1. Next, search for the dedicated power switch to your heating system. It’s similar to a light switch and can be found on or near your furnace. Move the switch down to shut off power.
    1. Your furnace should be turned off now.

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

What Causes a Furnace to Keep Running?

Occasionally correcting this problem can be as easy as changing 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 regulates your furnace’s blower motor. If the switch goes out, 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 communicate via a flashing red light on the front of your heating system.

Our Experts can diagnose and fix any issues 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.

Bad Thermostat

Like other things 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 needs. Additionally, you’ll be able to set and monitor your thermostat from just about anywhere with your phone.

Air Ducts Are Leaking

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 because the ductwork is leaking hot air in the attic.

Identifying 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 handling any air duct repair service that you require.

Rely 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 comes to furnaces, there’s a reason why we say we’re Experts in our industry. You can count 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 to schedule your appointment now.

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