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

Using a smart thermostat isn’t just smart for spending less on heating expenses. It can also let you know 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 notices an issue with your heating system. You’ll notice 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 get 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 brief period of time then switches off. This HVAC game of red light, green light prevents your home from heating up and can drive up your energy bill. It can also increase deterioration 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 detect your furnace is turning on and off frequently, since 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 simple ways you can prevent your furnace from short cycling.

Replace Your Air Filter Often

If your air filter is too dirty, it will restrict airflow. Your furnace will then shut off early to avoid overheating. We recommend replacing flat filters once a 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 run a test to see if that repairs 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 connected to it. Select “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 check 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 requires professional assistance. If this happens, call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for furnace repair.

Clean or Replace Your Furnace’s Flame Sensor

Having a dirty or malfunctioning flame sensor is another top explanation 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.

    • Take off 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 warmer indoor temperature.
    • When you switch 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 depends on 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 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 notice 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 combination 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 & Plumbing will be able to clean it without breaking 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 outdoors 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 blocked, 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 have a pressure switch that typically will prevent 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 a location that can be reached by little hands. Even this little amount is enough to trigger 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 experience short cycling and a furnace error code indicating the pressure switch was tripped.

An Expert HVAC technician from Service Experts Heating, Air Conditioning & Plumbing can look up the codes for you and diagnose the problem. Unfortunately, Nest has not evolved to the point where it can interpret the error codes furnace manufacturers create, so you will still need 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 & Plumbing, 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 book your appointment, contact us at 866-397-3787 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.