It's not unusual for heating systems to have a glitch once in a while. 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 properly working furnace again.
Examine the Air Filter
A dirty air filter creates problems for many homeowners and their HVAC system. Here's why. It limits airflow, forcing your furnace to 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 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 unpleasant.
We recommend replacing flat filters each 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 dusty and you should get a new one.
If the matter was connected to a clogged air filter, putting in a clean filter should fix this common issue when your heat won't turn off. If not, we recommend checking your thermostat settings next.
Check the Thermostat
Your thermostat controls your furnace and basically 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 easy as changing a wrong 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” means the furnace blower will only operate when the furnace does.
“On” indicates the furnace blower will operate constantly. This constant air flow can help with heat distribution but will also drive up your power bill and lead to 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 hearing. Switching it to "auto" should resolve the problem. It will also help you save money on your energy costs.
Confirm Your Temperature Setting
If your thermostat won't turn off heat, compare 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.
Remember that if it's extremely cold outside, your furnace will have to operate much longer than usual to keep your home warm. This is due to a big temperature difference between the cold air outside and the warm indoors.
As a check, you can try lowering the setting to match the room. Then, wait a couple of minutes. This should make the furnace turn off momentarily.
Replace the Batteries
If you use a programmable thermostat, it's likely battery powered. You can test putting in new batteries to see if that solves 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 move it to "off," you will need to cut the power.
Turn Off the Power
Thermostat seems 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 dedicated power switch.
- Go to your breaker box and locate the breaker labeled "furnace." Move the breaker switch to the right to cut power.
- Next, look for the dedicated power switch to your heating system. It looks like a light switch and can be found on or near your furnace. Move the switch down to cut power.
- Your furnace should be turned off now.
If you had to switch off your system at the breaker, call us at 303-647-5749 for professional service, as you may need furnace repair.
What Causes a Furnace to Keep Running?
Sometimes fixing 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 shut off.
Fan Limit Switch Needs Replacing
The furnace fan limit switch controls your furnace's blower motor. If the switch goes bad, 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 speak through 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.
Like anything else in your home, your thermostat can wear out over time and need to be replaced. If it's time for a new one, ask us about getting a smart thermostat.
These thermostats make it easy to save energy, because they develop 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 relies on ductwork to circulate hot air to vents across your home. If your home or ductwork is older, your furnace might be operating all the time because the ductwork is leaking hot air in the attic.
Identifying 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 diagnosing and taking care of any air duct repair service that you require.
Rely on Our Experts for All Your Furnace Repair Needs
Troubleshooting furnace problems 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 depend 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 303-647-5749 to schedule your appointment today.