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

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

The Google Nest has a function called Furnace Heads Up, which will let you know if it detects 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 typical issues is: “Nest noticed that your furnace shuts down within 15 minutes of heating.” Here’s what's doing on 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 switches off. This HVAC game of red light, green light prevents 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 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 recognize 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 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 replacing your filter by adding a Filter Reminder on your thermostat.

If you’ve replaced 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 display the wires connected to it. Choose "continue."
  • You’ll see system components displayed. 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 done.

Google says if the filter is clean or if your furnace didn’t clear the test, something else could be awry that needs professional help. If this happens, call Service Experts Heating & Air Conditioning at 407-329-7661 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 might short cycle. You can determine if there’s a problem by watching your furnace as it starts up. Here’s what to check 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 have to remove the door for this.
  • Switch on the furnace by setting the thermostat to a warmer indoor temperature.
  • When you switch on the heat, the fan will turn on 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 warm 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 turn off as a safety precaution. If your furnace is short cycling, you'll observe the flame and fan shutting off after a couple of seconds.

If you’re questioning how flame sensors could get dirty being bathed in fire continuously, 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 problem. 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 you need a new one.

Check Your Furnace’s Exhaust Pipe Often

Your high-efficiency furnace vents combustion gases outdoors 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 blocked, it can cause your furnace to overheat. 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 stop these situations from occurring. Households 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's accessible 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 trips the pressure switch, which shuts off the burners. If this is the root of your problem, you will encounter short cycling and a furnace error code specifying the pressure switch was tripped.

An Expert HVAC technician from Service Experts Heating & Air Conditioning can check 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 get 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 knowledge to resolve 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, call us at 407-329-7661 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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