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 a problem with your furnace.

The Google Nest has a function called Furnace Heads Up, which will alert you if it detects a problem with your heating system. You’ll see the alert 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 what's doing on 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,” it's saying your furnace is short cycling. Short cycling is when the furnace switches on for a short period of time then switches off. This HVAC game of red light, green light prevents your home from being warm and can increase your energy bill. It can also increase deterioration on your furnace. It may also be more likely to break 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 going. This feature can pick up on power interruptions that happen 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 prematurely to prevent overheating. We recommend replacing flat filters every month, and pleated filters every three months. It’s simple to stay on top of changing 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 do a test to see if that fixes the problem.

  • Press the ring to pull up the Quick View menu, where you’ll choose "settings" and then "equipment."
  • The thermostat will show the wires connected 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 give 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 wrong that needs professional help. If this happens, contact Church Services at 713-396-3760 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 paying attention to your furnace as it starts up. 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 have to remove the door for this.
  • Switch on the furnace by setting the thermostat to a warmer indoor temperature.
  • When you switch 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 ignite.
  • 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 precaution. If your furnace is short cycling, you'll notice the flame and fan shutting down 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 layer of carbon on the surface. Cleaning a dirty flame sensor will end the short cycling issue. This task is best left to an Expert. That's due to the fact an HVAC professional like Church Services 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 Often

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 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 life-threatening situation.

However, modern furnaces have a pressure switch that generally will stop these situations from happening. Households 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's accessible by tiny hands. Even this little amount is enough to trip the pressure switch. The irregular flow of air into and out of the system trips 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 Church Services can look up the codes for you and determine the problem. Unfortunately, Nest has not evolved to the point where it can read the error codes furnace manufacturers create, so you will still need a pro to assist you.

Let the Experts Handle Your Short Cycling Furnace

If you receive the message, “Nest noticed that your furnace shuts down within 15 minutes of heating,” you know what to do. At Church Services, our Experts have the knowledge to fix 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 713-396-3760 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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