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 let you know 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 senses an issue with your heating system. You’ll notice the warning on the thermostat, in the app and in your monthly Nest Home report.

One of the most typical problems 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 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 turns on for a short period of time then turns off. This HVAC game of red light, green light stops your home from heating up and can increase your energy bill. It can also increase wear and tear 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 detect your furnace is turning on and off often, because its blower fan might keep going. 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 limit airflow. Your furnace will then shut down prematurely to avoid overheating. We recommend replacing flat filters once a 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 changed your filter after receiving 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 select "settings" and then "equipment."
  • The thermostat will show the wires connected to it. Choose "continue."
  • You’ll see system components shown. Select "test."
  • Choose "Furnace Heads Up" and follow the instructions. Your furnace will run a 15-minute heating check 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 requires professional help. If this happens, contact Roy Inch & Sons Home Services by Enercare at 226-270-1164 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 might short cycle. You can tell if there’s a problem by paying attention to your furnace as it turns on. Here’s what to check 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 switch on the heat, the fan will turn on first. You should hear it turn on.
  • The ignitor will start 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 warm enough, the gas will switch on and the burners will light.
  • If the flame sensor can’t detect a flame, it’s usually due to the fact 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 few 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 problem. This task is best left to an Expert. That's due to the fact an HVAC professional like Roy Inch & Sons Home Services by Enercare will be able to clean it without damaging it or be able to tell you if you need a new one.

Check Your Furnace’s Exhaust Pipe Frequently

Your high-efficiency furnace exhausts combustion gases outdoors 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 clogged, 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 prevent these situations from occurring. Families with young children will often find their kids have stuffed toy cars, sticks or nuts into the exhaust if it’s in a location that can be reached by tiny hands. Even this small amount is enough to trigger the pressure switch. The irregular 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 encounter short cycling and a furnace error code specifying the pressure switch was triggered.

An Expert HVAC technician from Roy Inch & Sons Home Services by Enercare can look up 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 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 Roy Inch & Sons Home Services by Enercare, 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 226-270-1164 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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