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 costs. It can also alert you if there’s an issue with your furnace.

The Google Nest is equipped with a function called Furnace Heads Up, which will let you know if it senses 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 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 correct it.

Your Furnace is Short Cycling

When you get the message “Nest noticed that your furnace shuts down within 15 minutes of heating,” that means your furnace is short cycling. Short cycling is when the furnace switches on for a brief period of time then turns off. This HVAC game of red light, green light stops your home from being warm and can increase 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 sooner.

Without Furnace Heads Up, you might not detect your furnace is turning on and off frequently, because its blower fan might keep running. 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 keep 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 off prematurely to prevent overheating. We encourage changing flat filters every month, and pleated filters every three months. It’s easy to stay on top of replacing 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 repairs the problem.

  • Press the ring to bring 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."
  • Select "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 wrong that needs professional assistance. If this happens, contact Service Experts Heating & Air Conditioning at (713) 352-7887 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 starts up. 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.
  • Switch on the furnace by setting the thermostat to a higher indoor temperature.
  • When you switch on the heat, the fan will begin running first. You should notice 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 ignite.
  • If the flame sensor can’t sense a flame, it’s usually because it’s dirty or malfunctioning. 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 couple of seconds.

If you’re wondering 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 stop the short cycling issue. This task 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 Often

Your high-efficiency furnace vents combustion gases outdoors through a PVC pipe. This pipe can get blocked by snow or bird nests, so you’ll want to make sure it’s always clear. If the pipe gets plugged, it can result in your furnace overheating. It could also result in carbon monoxide flowing back into your home, creating a potentially deadly situation.

However, modern furnaces are equipped with a pressure switch that generally will prevent these situations from happening. Families 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's accessible by little hands. Even this little amount is enough to trip 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 experience short cycling and a furnace error code indicating the pressure switch was tripped.

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 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 Service Experts Heating & Air Conditioning, our Experts have the expertise to resolve 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 (713) 352-7887 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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