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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 broken thermostat or an electrical problem. If your gas furnace won’t shut off, here are a couple steps you can take to get a correctly working furnace again.

Examine 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 meet your ideal temperature.

This multiplies wear and tear on your furnace, as well as the likelihood of a malfunction and early failure.

It can also make your furnace overheat and shut off 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 increase your heating bill and make your home feel uncomfortable.

We encourage replacing flat filters monthly 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 replace it.

If the matter was connected to a clogged air filter, putting in a fresh filter should solve this common issue when your heat won’t turn off. If not, we recommend checking your thermostat settings next.

Check Out the Thermostat

Your thermostat controls your furnace and basically tells the unit when to turn on and off. It’s often to blame when your furnace won’t stop running.

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

Ensure 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 run when the furnace does.

“On” indicates the furnace blower will operate constantly. This constant air flow can help with heat circulation but will also drive up 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 hearing. Switching it to “auto” should resolve the problem. It will also help you save 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 running until it hits your desired temp.

Remember 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 big temperature difference between the cold air outside and the warm indoors.

As a test, you can try decreasing the thermostat to match the room. Then, wait a couple of minutes. This should make the furnace shut off momentarily.

Put in Fresh Batteries

If you use a programmable thermostat, it’s likely battery powered. You can try replacing the 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 switch it to “off,” you will need to turn off the power.

Turn Off the Power

Thermostat appears to be working fine but your furnace still won’t shut off? There are two places you can cut the power to your heating unit: at the breaker box and at its dedicated power switch.

    1. Head to your breaker box and find the breaker labeled “furnace.” Push the breaker switch to the right to shut off power.
    1. Next, look for the dedicated power switch to your heating system. It looks like a light switch and is located on or near your furnace. Move the switch down to cut power.
    1. Your furnace should be shut off now.

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

What Causes a Furnace to Keep Running?

Sometimes correcting this problem can be as simple as changing your air filter or adjusting thermostat settings. In other instances, 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 bad, it might seem like your furnace running nonstop, even though just the blower is running.

You might notice a furnace error code if there’s a problem with the limit switch. Your furnace will speak using 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. Often 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 as time passes and need to be replaced. If it’s time for a new one, ask us about getting a smart thermostat.

These thermostats make it simple to save energy, since they create an energy-efficient heating and cooling schedule based on your preferences. 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 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.

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.

Depend on Our Experts for All Your Furnace Repair Needs

Troubleshooting furnace problems can be annoying, particularly when it affects 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 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 to book your appointment now.

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