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

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

The Google Nest is equipped with a feature called Furnace Heads Up, which will alert you if it detects an issue 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 frequent 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 switches on for a brief period of time then switches 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 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 detect your furnace is turning on and off often, because its blower fan might keep going. This feature can detect power interruptions that take place 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.

Replace Your Air Filter Regularly

If your air filter is too dirty, it will restrict airflow. Your furnace will then shut off early to prevent overheating. We encourage replacing flat filters once a month, and pleated filters every three months. It’s easy 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 repairs the problem.

  • Push the ring to pull up the Quick View menu, where you’ll choose "settings" and then "equipment."
  • The thermostat will show the wires linked to it. Choose "continue."
  • You’ll see system components shown. Select "test."
  • Choose "Furnace Heads Up" and follow the instructions. Your furnace will go through 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 clear the test, something else could be awry that needs professional assistance. If this happens, call Service Experts Heating & Air Conditioning at 239-908-6991 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 watching your furnace as it turns on. 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.
  • Turn on the furnace by setting the thermostat to a higher indoor temperature.
  • When you turn 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 varies according to 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 due to the fact it’s dirty or defective. Your furnace will then shut off as a safety measure. If your furnace is short cycling, you'll observe the flame and fan shutting down after a few seconds.

If you’re questioning how flame sensors could get dirty being bathed in fire constantly, a blend of moisture and chemicals in the air form a thin layer of carbon on the surface. Cleaning a dirty flame sensor will stop the short cycling issue. This job is best left to an Expert. That's due to the fact an HVAC professional like Service Experts Heating & Air Conditioning 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 Frequently

Your high-efficiency furnace vents combustion gases outside through a PVC pipe. This pipe can get clogged by snow or bird nests, so you’ll want to make sure 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 life-threatening situation.

However, modern furnaces are equipped with a pressure switch that generally will stop these situations from occurring. Families 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's accessible by little hands. Even this small amount is enough to trip the pressure switch. The uneven 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 triggered.

An Expert HVAC technician from Service Experts Heating & Air Conditioning can look up 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 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 Service Experts Heating & Air Conditioning, 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 book your appointment, contact us at 239-908-6991 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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