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 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 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 frequent problems is: “Nest noticed that your furnace shuts down within 15 minutes of heating.” Here’s what's doing on and how you can fix 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 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 notice your furnace is turning on and off often, because its blower fan might keep going. This feature can pick up on power interruptions that occur 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 Often

If your air filter is too dirty, it will restrict airflow. Your furnace will then shut down early to avoid overheating. We recommend replacing flat filters every month, and pleated filters every three months. It’s simple to stay on top of replacing your filter by setting up a Filter Reminder on your thermostat.

If you’ve replaced your filter after receiving a Furnace Heads Up alert, you can do a test to see if that repairs the problem.

  • Press the ring to pull up the Quick View menu, where you’ll choose "settings" and then "equipment."
  • The thermostat will display 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 finished.

Google says if the filter is clean or if your furnace didn’t clear the test, something else could be wrong that requires professional assistance. If this happens, call Bryant Heating & Cooling Service Experts at 226-773-3357 for furnace repair.

Clean or Replace Your Furnace’s Flame Sensor

Having a dirty or bad flame sensor is another top reason why your furnace is short cycling. You can tell if there’s a problem by paying attention to your furnace as it starts up. Here’s what to check for.

  • Remove the door from your furnace so you can see the burners. If you have a viewport in the furnace door, you may not have to remove the door for this.
  • Turn on the furnace by setting the thermostat to a warmer 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 depends on the furnace model.
  • Once the ignitor is hot enough, the gas will turn on and the burners will light.
  • If the flame sensor can’t detect a flame, it’s usually because it’s dirty or malfunctioning. Your furnace will then turn off as a safety measure. If your furnace is short cycling, you'll notice the flame and fan shutting off after a few seconds.

If you’re questioning how flame sensors could get dirty being bathed in fire continuously, a blend 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 problem. This task is best left to an Expert. That's due to the fact an HVAC professional like Bryant Heating & Cooling Service Experts 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 obstructed by snow or bird nests, so you’ll want to ensure that it’s always clear. If the pipe gets blocked, it can cause your furnace to overheat. It could also cause carbon monoxide to flow back into your home, creating a potentially deadly situation.

However, modern furnaces have a pressure switch that generally will prevent these situations from occurring. Households 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 little 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 down the burners. If this is the underlying cause of your problem, you will experience short cycling and a furnace error code specifying the pressure switch was triggered.

An Expert HVAC technician from Bryant Heating & Cooling Service Experts can check 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 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 Bryant Heating & Cooling Service Experts, our Experts have the expertise 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 226-773-3357 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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