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

Using a smart thermostat isn’t just smart for saving on heating expenses. It can also let you know if there’s a problem with your furnace.

The Google Nest is equipped with a feature called Furnace Heads Up, which will alert you if it detects a problem with your heating system. You’ll notice the alert on the thermostat, in the app and in your monthly Nest Home report.

One of the most frequent issues is: “Nest noticed that your furnace shuts down within 15 minutes of heating.” Here’s what's doing on 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 being warm 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, because 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 keep your furnace from short cycling.

Replace Your Air Filter Regularly

If your air filter is too dirty, it will restrict airflow. Your furnace will then shut off prematurely to prevent overheating. We encourage 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 getting a Furnace Heads Up alert, you can run a test to see if that fixes the problem.

  • Push the ring to pull up the Quick View menu, where you’ll select "settings" and then "equipment."
  • The thermostat will display the wires linked to it. Select "continue."
  • You’ll see system components shown. Hit "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 wrong that requires professional help. If this happens, contact Matz-Rightway at 631-406-9220 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 determine if there’s a problem by paying attention to your furnace as it starts up. Here’s what to look 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 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 notice 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 warm 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 measure. If your furnace is short cycling, you'll notice the flame and fan shutting off after a couple of seconds.

If you’re wondering 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 task is best left to an Expert. That's because an HVAC professional like Matz-Rightway 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 exhausts 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 result in your furnace overheating. It could also cause carbon monoxide to flow back into your home, creating a potentially deadly situation.

However, modern furnaces are equipped with a pressure switch that generally will stop these situations from happening. Households 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 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 underlying cause of your problem, you will encounter short cycling and a furnace error code indicating the pressure switch was tripped.

An Expert HVAC technician from Matz-Rightway can check the codes for you and diagnose the problem. Unfortunately, Nest has not developed to the point where it can read the error codes furnace manufacturers create, 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 Matz-Rightway, our Experts have the expertise 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 request your appointment, contact us at 631-406-9220 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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