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

Having a smart thermostat isn’t just wise for saving on heating expenses. 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 alert you if it notices an issue 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 typical issues 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 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 switches 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 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 frequently, since its blower fan might keep running. This feature can recognize power interruptions that take place 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 Often

If your air filter is too dirty, it will limit airflow. Your furnace will then shut off early to prevent 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 adding 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 fixes the problem.

• • Press the ring to pull up the Quick View menu, where you’ll choose “settings” and then “equipment.”

• • The thermostat will display the wires linked to it. Choose “continue.”

• • You’ll see system components shown. Hit “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 done.

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 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 might short cycle. You can determine if there’s a problem by paying attention to your furnace as it starts up. 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 have to remove the door for this.

• • Switch on the furnace by setting the thermostat to a higher indoor temperature.

• • When you switch on the heat, the fan will turn on 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 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 due to the fact it’s dirty or defective. Your furnace will then shut 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 blend of moisture and chemicals in the air form a thin layer 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 Service Experts Heating, Air Conditioning & Plumbing 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 plugged, it can result in your furnace overheating. It could also result in carbon monoxide flowing back into your home, creating a potentially fatal situation.

However, modern furnaces have a pressure switch that generally 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 can be reached 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 underlying cause of your problem, you will experience short cycling and a furnace error code specifying the pressure switch was triggered.

An Expert HVAC technician from Service Experts Heating, Air Conditioning & Plumbing can check the codes for you and determine the problem. Unfortunately, Nest has not evolved to the point where it can interpret the error codes furnace manufacturers create, so you will still require 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 back our repairs with a 100% Satisfaction Guarantee for one year.* To request your appointment, call us at 866-397-3787 or schedule online.

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*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.