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 expenses. It can also alert you if there’s an issue with your furnace.

The Google Nest is equipped with 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 issues is: “Nest noticed that your furnace shuts down within 15 minutes of heating.” Here’s why this is happening and how you can correct 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 turns on for a short period of time then switches 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 wear and tear 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 notice your furnace is turning on and off often, since its blower fan might keep running. This feature can recognize 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 prevent your furnace from short cycling.

Change Your Air Filter Regularly

If your air filter is too dirty, it will limit airflow. Your furnace will then shut off prematurely to prevent overheating. We encourage changing flat filters once a month, and pleated filters every three months. It’s easy to stay on top of replacing 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 display the wires connected to it. Choose "continue."
  • You’ll see system components shown. Hit "test."
  • Select "Furnace Heads Up" and follow the instructions. Your furnace will go through a 15-minute heating test 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 needs professional assistance. If this happens, call 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 explanation why your furnace might short cycle. You can tell if there’s a problem by watching your furnace as it turns on. 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 switch on the heat, the fan will turn on 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 varies according to 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 defective. Your furnace will then shut off as a safety precaution. If your furnace is short cycling, you'll notice the flame and fan shutting down after a couple of seconds.

If you’re wondering how flame sensors could get dirty being bathed in fire constantly, 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 Frequently

Your high-efficiency furnace vents combustion gases outdoors through a PVC pipe. This pipe can get obstructed 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 cause carbon monoxide to flow back into your home, creating a potentially fatal situation.

However, modern furnaces are equipped with a pressure switch that typically will stop these situations from happening. Families with young children will often find their kids have stuffed toy cars, sticks or nuts into the exhaust if it’s in an area that can be reached by little hands. Even this small amount is enough to trigger the pressure switch. The uneven flow of air into and out of the system triggers 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 specifying the pressure switch was triggered.

An Expert HVAC technician from Service Experts Heating & Air Conditioning can look up 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 produce, so you will still need a pro to assist you.

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 Service Experts Heating & Air Conditioning, our Experts have the knowledge to fix 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 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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