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

Having 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 has a feature called Furnace Heads Up, which will let you know if it notices a problem with your heating system. You’ll see the warning on the thermostat, in the app and in your monthly Nest Home report.

One of the most common problems 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 see the message “Nest noticed that your furnace shuts down within 15 minutes of heating,” that means 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 prevents your home from being warm and can drive up your energy bill. It can also increase deterioration on your furnace. It may also be more susceptible to breaking down and may even need to be replaced more quickly.

Without Furnace Heads Up, you might not detect your furnace is turning on and off frequently, since its blower fan might keep running. This feature can recognize 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 Often

If your air filter is too dirty, it will limit airflow. Your furnace will then shut down early to prevent overheating. We recommend replacing flat filters once a month, and pleated filters every three months. It’s simple 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 run a test to see if that fixes the problem.

  • Press the ring to pull up the Quick View menu, where you’ll select "settings" and then "equipment."
  • The thermostat will show the wires connected to it. Choose "continue."
  • You’ll see system components displayed. Select "test."
  • Choose "Furnace Heads Up" and follow the instructions. Your furnace will run a 15-minute heating test and tell 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 requires professional assistance. If this happens, call All American Air Service Experts at 386-310-2061 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 might short cycle. You can determine if there’s a problem by paying attention to your furnace as it starts up. Here’s what to check for.

  • Remove the door from your furnace so you can look at the burners. If you have a viewport in the furnace door, you may not have to remove the door for this.
  • Switch on the furnace by setting the thermostat to a warmer indoor temperature.
  • When you turn on the heat, the fan will begin running first. You should notice it turn on.
  • The ignitor will begin 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 hot 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 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 wondering 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 job is best left to an Expert. That's because an HVAC professional like All American Air 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 Frequently

Your high-efficiency furnace vents combustion gases outside 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 plugged, it can cause your furnace to overheat. It could also result in carbon monoxide flowing back into your home, creating a potentially fatal 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 can be reached 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 encounter short cycling and a furnace error code specifying the pressure switch was triggered.

An Expert HVAC technician from All American Air Service Experts can check the codes for you and diagnose the problem. Unfortunately, Nest has not developed to the point where it can interpret the error codes furnace manufacturers create, so you will still require a pro to assist you.

Let the Experts Solve Your Short Cycling Furnace

If you receive the message, “Nest noticed that your furnace shuts down within 15 minutes of heating,” you know what to do. At All American Air Service Experts, our Experts have the expertise to fix 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 request your appointment, contact us at 386-310-2061 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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