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 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 a problem 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 frequent 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 switches 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 wear and tear 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 often, because its blower fan might keep running. 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 limit airflow. Your furnace will then shut down prematurely to prevent overheating. We encourage replacing flat filters every month, and pleated filters every three months. It’s simple to stay on top of replacing 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 run a test to see if that repairs the problem.

  • Push the ring to pull 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 shown. Select "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 done.

Google says if the filter is clean or if your furnace didn’t clear the test, something else could be awry that requires professional help. If this happens, call Service Experts Home Services by Enercare at 613-817-1591 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 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 look at the burners. If you have a viewport in the furnace door, you may not have 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 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 detect a flame, it’s usually because it’s dirty or faulty. Your furnace will then turn off as a safety precaution. 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 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 Home Services by Enercare 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 Frequently

Your high-efficiency furnace vents combustion gases outside through a PVC pipe. This pipe can get obstructed by snow or bird nests, so you’ll want to make sure it’s always clear. If the pipe gets blocked, it can result in your furnace overheating. 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 typically will prevent 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's accessible by tiny hands. Even this little amount is enough to trigger the pressure switch. The irregular 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 tripped.

An Expert HVAC technician from Service Experts Home Services by Enercare 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 create, so you will still need a pro to assist you.

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 Home Services by Enercare, our Experts have the knowledge 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 book your appointment, contact us at 613-817-1591 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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