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

Using a smart thermostat isn’t just wise 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 alert you if it detects a problem with your heating system. You’ll see 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 what's doing on and how you can correct it.

Your Furnace is Short Cycling

When you see 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 short 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 susceptible to breaking down and may even require replacement sooner.

Without Furnace Heads Up, you might not notice your furnace is turning on and off often, since its blower fan might keep going. 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 keep your furnace from short cycling.

Replace Your Air Filter Regularly

If your air filter is too dirty, it will restrict airflow. Your furnace will then shut off prematurely to prevent overheating. We encourage changing flat filters once a month, and pleated filters every three months. It’s simple to stay on top of changing your filter by setting up a Filter Reminder on your thermostat.

If you’ve changed your filter after receiving a Furnace Heads Up alert, you can do a test to see if that fixes 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 displayed. Select "test."
  • Select "Furnace Heads Up" and follow the instructions. Your furnace will go through a 15-minute heating check and tell you the results when it’s done.

Google says if the filter is clean or if your furnace didn’t pass the test, something else could be wrong that needs professional help. If this happens, call Aramendia Plumbing, Heating and Air at 210-404-4233 for furnace repair.

Clean or Replace Your Furnace’s Flame Sensor

Having a dirty or bad flame sensor is another top reason why your furnace is short cycling. You can tell if there’s a problem by watching your furnace as it starts up. Here’s what to look 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 need to remove the door for this.
  • Switch on the furnace by setting the thermostat to a higher indoor temperature.
  • When you turn on the heat, the fan will begin running first. You should notice 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 turn on and the burners will light.
  • If the flame sensor can’t detect a flame, it’s usually because 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 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 issue. This task is best left to an Expert. That's due to the fact an HVAC professional like Aramendia Plumbing, Heating and Air 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 cause your furnace to overheat. It could also result in carbon monoxide flowing back into your home, creating a potentially fatal situation.

However, modern furnaces are equipped with a pressure switch that typically will prevent 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 a location that can be reached by little hands. Even this little 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 underlying cause of your problem, you will encounter short cycling and a furnace error code specifying the pressure switch was tripped.

An Expert HVAC technician from Aramendia Plumbing, Heating and Air 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 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 Aramendia Plumbing, Heating and Air, our Experts have the knowledge to fix 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 request your appointment, contact us at 210-404-4233 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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