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 an issue with your furnace.

The Google Nest is equipped with a function called Furnace Heads Up, which will alert you if it senses an issue 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 typical issues is: “Nest noticed that your furnace shuts down within 15 minutes of heating.” Here’s what's doing on 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,” 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 heating up and can drive up your energy bill. It can also increase wear and tear on your furnace. It may also be more susceptible to breaking down and may even require replacement more quickly.

Without Furnace Heads Up, you might not notice your furnace is turning on and off often, because its blower fan might keep running. This feature can detect power interruptions that take place 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 restrict airflow. Your furnace will then shut off early to prevent overheating. We recommend replacing flat filters every month, and pleated filters every three months. It’s easy to stay on top of replacing your filter by adding 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 fixes the problem.

  • Press the ring to bring up the Quick View menu, where you’ll choose "settings" and then "equipment."
  • The thermostat will show the wires linked to it. Select "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 check and tell you the results when it’s done.

Google says if the filter is clean or if your furnace didn’t clear the test, something else could be awry that requires professional assistance. If this happens, contact Service Experts Heating & Air Conditioning at 352-414-4006 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 watching your furnace as it starts up. Here’s what to look 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.
  • 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 hear 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 warm enough, the gas will switch on and the burners will light.
  • If the flame sensor can’t detect 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 off after a couple of seconds.

If you’re questioning 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 stop the short cycling issue. This job is best left to an Expert. That's due to the fact an HVAC professional like Service Experts Heating & Air Conditioning 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 exhausts combustion gases outdoors through a PVC pipe. This pipe can get blocked by snow or bird nests, so you’ll want to make sure 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 fatal situation.

However, modern furnaces are equipped with a pressure switch that generally will prevent 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 trip 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 experience short cycling and a furnace error code specifying the pressure switch was tripped.

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

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, our Experts have the knowledge 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 352-414-4006 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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