Solved: Nest Noticed Your Furnace Shuts Down Within 15 Minutes of Heating 

Having a smart thermostat isn’t just wise for saving on heating costs. It can also alert you if there’s an issue with your furnace.

The Google Nest has a feature called Furnace Heads Up, which will alert you if it senses a problem with your heating system. You’ll notice the alert on the thermostat, in the app and in your monthly Nest Home report.

One of the most frequent issues is: “Nest noticed that your furnace shuts down within 15 minutes of heating.” Here’s why this is happening and how you can fix it.

Your Furnace is Short Cycling

When you get the message “Nest noticed that your furnace shuts down within 15 minutes of heating,” it’s saying your furnace is short cycling. Short cycling is when the furnace turns on for a short period of time then turns off. This HVAC game of red light, green light stops your home from being warm and can increase your energy bill. It can also increase deterioration on your furnace. It may also be more susceptible to breaking down and may even require replacement sooner.

Without Furnace Heads Up, you might not notice your furnace is turning on and off frequently, since its blower fan might keep running. This feature can detect power interruptions that occur during short cycling.

How Do I Keep My Furnace from Short Cycling?

There are a few simple ways you can keep your furnace from short cycling.

Change Your Air Filter Regularly

If your air filter is too dirty, it will restrict airflow. Your furnace will then shut down prematurely to avoid overheating. We encourage changing flat filters every month, and pleated filters every three months. It’s easy to stay on top of changing your filter by setting up a Filter Reminder on your thermostat.

If you’ve changed your filter after getting a Furnace Heads Up alert, you can do a test to see if that fixes the problem.

• • Press the ring to bring up the Quick View menu, where you’ll select “settings” and then “equipment.”

• • The thermostat will display the wires connected to it. Choose “continue.”

• • You’ll see system components displayed. Hit “test.”

• • Choose “Furnace Heads Up” and follow the instructions. Your furnace will go through a 15-minute heating test and give you the results when it’s finished.

Google says if the filter is clean or if your furnace didn’t clear the test, something else could be awry that needs professional assistance. If this happens, call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for furnace repair.

Clean or Replace Your Furnace’s Flame Sensor

Having a dirty or bad flame sensor is another top reason why your furnace is short cycling. You can tell if there’s a problem by paying attention to your furnace as it starts up. Here’s what to check for.

• • Take off the door from your furnace so you can see the burners. If you have a viewport in the furnace door, you may not need to remove the door for this.

• • Turn on the furnace by setting the thermostat to a higher indoor temperature.

• • When you turn on the heat, the fan will begin running first. You should notice it turn on.

• • The ignitor will start to glow. The ignitor is either on the left or right of the burners, but it depends on the furnace model.

• • Once the ignitor is warm enough, the gas will switch on and the burners will light.

• • If the flame sensor can’t sense a flame, it’s usually because it’s dirty or defective. Your furnace will then shut off as a safety precaution. If your furnace is short cycling, you’ll observe the flame and fan shutting down after a few seconds.

If you’re wondering how flame sensors could get dirty being bathed in fire continuously, a combination of moisture and chemicals in the air form a thin coating of carbon on the surface. Cleaning a dirty flame sensor will end the short cycling issue. This task is best left to an Expert. That’s because an HVAC professional like Service Experts Heating, Air Conditioning & Plumbing will be able to clean it without breaking it or be able to tell you if it needs to be replaced.

Check Your Furnace’s Exhaust Pipe Often

Your high-efficiency furnace vents combustion gases outdoors through a PVC pipe. This pipe can get clogged by snow or bird nests, so you’ll want to ensure that it’s always clear. If the pipe gets blocked, it can cause your furnace to overheat. It could also result in carbon monoxide flowing back into your home, creating a potentially life-threatening situation.

However, modern furnaces have a pressure switch that typically will stop these situations from happening. Families with young children will often find their kids have jammed toy cars, sticks or nuts into the exhaust if it’s in a location that’s accessible by tiny hands. Even this little amount is enough to trigger the pressure switch. The uneven flow of air into and out of the system trips the pressure switch, which shuts down the burners. If this is the underlying cause of your problem, you will encounter short cycling and a furnace error code indicating the pressure switch was triggered.

An Expert HVAC technician from Service Experts Heating, Air Conditioning & Plumbing can check the codes for you and determine the problem. Unfortunately, Nest has not evolved to the point where it can interpret the error codes furnace manufacturers create, so you will still need a pro to assist you.

Let the Experts Handle Your Short Cycling Furnace

If you get the message, “Nest noticed that your furnace shuts down within 15 minutes of heating,” you know what to do. At Service Experts Heating, Air Conditioning & Plumbing, our Experts have the expertise to resolve any furnace problem quickly and affordably. What’s even better is that we back our repairs with a 100% Satisfaction Guarantee for one year.* To book your appointment, call us at 866-397-3787 or schedule online.

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*Not applicable to the Advantage Program. See your signed Advantage Program Agreement for full details and exclusions. 100% Satisfaction Guarantee is subject to certain restrictions and limitations as set forth in the applicable Terms and Conditions.