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

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

The Google Nest is equipped with 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 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 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 turns on for a short period of time then turns off. This HVAC game of red light, green light stops your home from being warm and can drive up your energy bill. It can also increase deterioration 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 frequently, because its blower fan might keep going. This feature can detect 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.

Change Your Air Filter Regularly

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

  • Press the ring to bring up the Quick View menu, where you’ll select "settings" and then "equipment."
  • The thermostat will show the wires linked to it. Choose "continue."
  • You’ll see system components displayed. Select "test."
  • Select "Furnace Heads Up" and follow the instructions. Your furnace will go through a 15-minute heating check 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 assistance. If this happens, contact Midland Air Service Experts at 803-399-7208 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 is short cycling. You can determine 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 see the burners. If you have a viewport in the furnace door, you may not need to remove the door for this.
  • Turn on the furnace by setting the thermostat to a higher indoor temperature.
  • When you turn on the heat, the fan will turn on 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 depends on 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 turn off as a safety precaution. 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 constantly, a combination 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 issue. This task is best left to an Expert. That's because an HVAC professional like Midland Air 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 Often

Your high-efficiency furnace vents combustion gases outside through a PVC pipe. This pipe can get blocked by snow or bird nests, so you’ll want to ensure that it’s always clear. If the pipe gets plugged, 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 are equipped with a pressure switch that typically will prevent these situations from happening. Families with young children will often find their kids have jammed toy cars, sticks or nuts into the exhaust if it’s in an area that can be reached by tiny hands. Even this small amount is enough to trigger the pressure switch. The uneven 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 encounter short cycling and a furnace error code indicating the pressure switch was tripped.

An Expert HVAC technician from Midland Air 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 help you out.

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 Midland Air Service Experts, our Experts have the knowledge to fix 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, contact us at 803-399-7208 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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