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

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

The Google Nest has a feature called Furnace Heads Up, which will let you know if it detects an issue with your heating system. You’ll notice the alert on the thermostat, in the app and in your monthly Nest Home report.

One of the most typical 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 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 wear and tear on your furnace. It may also be more likely to break down and may even require replacement more quickly.

Without Furnace Heads Up, you might not notice 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 easy ways you can prevent your furnace from short cycling.

Replace Your Air Filter Often

If your air filter is too dirty, it will limit airflow. Your furnace will then shut down prematurely to avoid overheating. We recommend changing flat filters every month, and pleated filters every three months. It’s easy to stay on top of changing 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.

  • Push the ring to bring up the Quick View menu, where you’ll select "settings" and then "equipment."
  • The thermostat will display the wires connected to it. Select "continue."
  • You’ll see system components displayed. Hit "test."
  • Select "Furnace Heads Up" and follow the instructions. Your furnace will go through 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 pass the test, something else could be wrong that needs professional assistance. If this happens, call Air Engineers Service Experts at 904-450-5672 for furnace repair.

Clean or Replace Your Furnace’s Flame Sensor

Having a dirty or bad flame sensor is another top explanation 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 check 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 have to remove the door for this.
  • Switch 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 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 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 shut off as a safety precaution. If your furnace is short cycling, you'll observe the flame and fan shutting down after a few 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 due to the fact an HVAC professional like Air Engineers Service Experts will be able to clean it without damaging it or be able to tell you if you need a new one.

Check Your Furnace’s Exhaust Pipe Often

Your high-efficiency furnace exhausts combustion gases outside 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 clogged, it can cause your furnace to overheat. It could also result in carbon monoxide flowing back into your home, creating a potentially life-threatening situation.

However, modern furnaces have a pressure switch that typically will stop these situations from occurring. Families with small 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 little hands. Even this small amount is enough to trip the pressure switch. The irregular flow of air into and out of the system triggers the pressure switch, which shuts down the burners. If this is the root of your problem, you will experience short cycling and a furnace error code indicating the pressure switch was tripped.

An Expert HVAC technician from Air Engineers Service Experts can look up 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 produce, so you will still need 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 Air Engineers 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 book your appointment, call us at 904-450-5672 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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