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

Using a smart thermostat isn’t just smart for spending less on heating costs. It can also alert you if there’s a problem with your furnace.

The Google Nest is equipped with 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 typical 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 switches on for a brief period of time then turns off. This HVAC game of red light, green light stops your home from heating up and can drive up your energy bill. It can also increase deterioration on your furnace. It may also be more likely to break 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 going. This feature can detect power interruptions that happen 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 Often

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

If you’ve replaced your filter after getting a Furnace Heads Up alert, you can run a test to see if that repairs the problem.

  • Press the ring to pull up the Quick View menu, where you’ll choose "settings" and then "equipment."
  • The thermostat will display the wires linked to it. Choose "continue."
  • You’ll see system components shown. Select "test."
  • Select "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 pass the test, something else could be awry that needs professional assistance. If this happens, call Peachtree Service Experts at 678-235-9699 for furnace repair.

Clean or Replace Your Furnace’s Flame Sensor

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

  • Take off the door from your furnace so you can look at 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 turn on 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 ignite.
  • If the flame sensor can’t sense a flame, it’s usually because it’s dirty or faulty. Your furnace will then shut off as a safety precaution. If your furnace is short cycling, you'll observe the flame and fan shutting off after a few seconds.

If you’re questioning how flame sensors could get dirty being bathed in fire constantly, a blend 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 due to the fact an HVAC professional like Peachtree Service Experts will be able to clean it without damaging it or be able to tell you if it needs to be replaced.

Check Your Furnace’s Exhaust Pipe Often

Your high-efficiency furnace exhausts combustion gases outside through a PVC pipe. This pipe can get obstructed by snow or bird nests, so you’ll want to make sure it’s always clear. If the pipe gets plugged, it can cause your furnace to overheat. It could also cause carbon monoxide to flow 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. Households 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 little hands. Even this little amount is enough to trigger the pressure switch. The irregular flow of air into and out of the system trips the pressure switch, which shuts off the burners. If this is the root of your problem, you will experience short cycling and a furnace error code indicating the pressure switch was triggered.

An Expert HVAC technician from Peachtree Service Experts can check the codes for you and determine the problem. Unfortunately, Nest has not developed to the point where it can read the error codes furnace manufacturers produce, so you will still require a pro to help you out.

Let the Experts Solve 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 Peachtree Service Experts, our Experts have the expertise to resolve any furnace problem quickly and affordably. What’s even better is that we stand behind our repairs with a 100% Satisfaction Guarantee for one year.* To book your appointment, contact us at 678-235-9699 or schedule online.


*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.

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