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

Using a smart thermostat isn’t just wise for saving on heating costs. It can also alert you if there’s a problem 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 typical problems is: “Nest noticed that your furnace shuts down within 15 minutes of heating.” Here’s what's doing on and how you can fix 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 turns off. This HVAC game of red light, green light stops 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 need to be replaced sooner.

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 detect power interruptions that happen during short cycling.

How Do I Keep My Furnace from Short Cycling?

There are a few easy ways you can keep your furnace from short cycling.

Change Your Air Filter Regularly

If your air filter is too dirty, it will limit airflow. Your furnace will then shut down early to prevent overheating. We recommend replacing flat filters every 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 changed 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 pull up the Quick View menu, where you’ll choose "settings" and then "equipment."
The thermostat will show the wires connected to it. Choose "continue."
You’ll see system components displayed. Hit "test."
Choose "Furnace Heads Up" and follow the instructions. Your furnace will run 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 clear the test, something else could be wrong that needs professional help. If this happens, contact Becht/Givens Service Experts at 502-785-8230 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 turns on. Here’s what to look for.

Remove 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.
Turn 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 hear it turn on.
The ignitor will start 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 warm enough, the gas will switch on and the burners will light.
If the flame sensor can’t sense a flame, it’s usually because it’s dirty or malfunctioning. Your furnace will then turn off as a safety precaution. If your furnace is short cycling, you'll notice the flame and fan shutting off after a few seconds.

If you’re questioning how flame sensors could get dirty being bathed in fire constantly, 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 because an HVAC professional like Becht/Givens Service Experts will be able to clean it without breaking it or be able to tell you if it needs to be replaced.

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 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 deadly situation.

However, modern furnaces are equipped with a pressure switch that typically will prevent these situations from occurring. Households with young children will often find their kids have jammed toy cars, sticks or nuts into the exhaust if it’s in a location that's accessible by tiny hands. Even this small amount is enough to trip 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 specifying the pressure switch was tripped.

An Expert HVAC technician from Becht/Givens Service Experts can check the codes for you and determine the problem. Unfortunately, Nest has not developed to the point where it can interpret the error codes furnace manufacturers produce, so you will still require 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 Becht/Givens 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, contact us at 502-785-8230 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.