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

Using a smart thermostat isn’t just wise for spending less on heating costs. It can also let you know if there’s an issue with your furnace.

The Google Nest has a function called Furnace Heads Up, which will alert you if it senses 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 common problems is: “Nest noticed that your furnace shuts down within 15 minutes of heating.” Here’s why this is happening 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 short period of time then turns 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 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 pick up on power interruptions that take place 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 down prematurely to avoid overheating. We recommend changing 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 replaced your filter after receiving a Furnace Heads Up alert, you can run 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. Select "test."
  • Select "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 needs professional assistance. If this happens, call Robinson Service Experts at 847-306-8730 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 determine if there’s a problem by watching your furnace as it turns on. Here’s what to look 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 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 defective. Your furnace will then turn off as a safety measure. If your furnace is short cycling, you'll observe 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 continuously, a blend of moisture and chemicals in the air form a thin coating 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 because an HVAC professional like Robinson Service Experts will be able to clean it without breaking it or be able to tell you if it needs to be replaced.

Check Your Furnace’s Exhaust Pipe Often

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 plugged, it can result in your furnace overheating. 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 typically 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 little hands. Even this little 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 indicating the pressure switch was tripped.

An Expert HVAC technician from Robinson Service Experts can check the codes for you and diagnose the problem. Unfortunately, Nest has not evolved to the point where it can read the error codes furnace manufacturers create, so you will still require a pro to help you out.

Let the Experts Solve 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 Robinson Service Experts , 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, call us at 847-306-8730 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.