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

Using a smart thermostat isn’t just wise for saving 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 notice 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 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,” it's saying your furnace is short cycling. Short cycling is when the furnace switches on for a brief period of time then switches off. This HVAC game of red light, green light prevents 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 susceptible to breaking down and may even require replacement more quickly.

Without Furnace Heads Up, you might not detect your furnace is turning on and off often, 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 easy ways you can prevent your furnace from short cycling.

Replace Your Air Filter Regularly

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 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 displayed. 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 finished.

Google says if the filter is clean or if your furnace didn’t clear the test, something else could be wrong that needs professional assistance. If this happens, contact Service Experts Home Services by Enercare at 289-273-2229 for furnace repair.

Clean or Replace Your Furnace’s Flame Sensor

Having a dirty or malfunctioning 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 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.
  • Switch on the furnace by setting the thermostat to a warmer indoor temperature.
  • When you turn 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 hot 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 faulty. Your furnace will then shut off as a safety measure. 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 layer 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 because an HVAC professional like Service Experts Home Services by Enercare will be able to clean it without breaking it or be able to tell you if you need a new one.

Check Your Furnace’s Exhaust Pipe Often

Your high-efficiency furnace vents combustion gases outdoors through a PVC pipe. This pipe can get clogged 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 result in carbon monoxide flowing back into your home, creating a potentially fatal situation.

However, modern furnaces have a pressure switch that generally will prevent these situations from happening. Families with small children will often find their kids have jammed toy cars, sticks or nuts into the exhaust if it’s in an area that's accessible by tiny hands. Even this little amount is enough to trip the pressure switch. The uneven flow of air into and out of the system triggers the pressure switch, which shuts down 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 Service Experts Home Services by Enercare 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 create, so you will still require a pro to assist you.

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 Home Services by Enercare, our Experts have the knowledge to resolve 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 289-273-2229 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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