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 an issue with your furnace. 

The Google Nest has a feature called Furnace Heads Up, which will alert you if it notices a problem with your heating system. You’ll see the alert on the thermostat, in the app and in your monthly Nest Home report. 

One of the most frequent 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 get 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 drive up your energy bill. It can also increase wear and tear on your furnace. It may also be more likely to break down and may even need to be replaced more quickly. 

Without Furnace Heads Up, you might not notice your furnace is turning on and off often, since 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 easy 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 recommend changing flat filters every month, and pleated filters every three months. It’s simple 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 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.” 
• 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 done. 

Google says if the filter is clean or if your furnace didn’t pass the test, something else could be wrong that requires professional help. If this happens, call 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 bad flame sensor is another top explanation why your furnace might short cycle. You can tell if there’s a problem by watching your furnace as it starts up. Here’s what to check for. 

• Remove 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 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 varies according to the furnace model. 

• Once the ignitor is hot enough, the gas will switch on and the burners will light. 
• If the flame sensor can’t sense a flame, it’s usually due to the fact it’s dirty or defective. Your furnace will then shut off as a safety precaution. If your furnace is short cycling, you’ll notice the flame and fan shutting off after a couple of seconds. 

If you’re wondering how flame sensors could get dirty being bathed in fire continuously, a blend 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 task is best left to an Expert. That’s due to the fact 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 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 clogged, it can result in your furnace overheating. It could also result in carbon monoxide flowing back into your home, creating a potentially life-threatening situation. 

However, modern furnaces are equipped with a pressure switch that generally will stop these situations from happening. Families with small children will often find their kids have stuffed toy cars, sticks or nuts into the exhaust if it’s in a location that can be reached by tiny hands. Even this little amount is enough to trigger the pressure switch. The uneven flow of air into and out of the system triggers the pressure switch, which shuts down the burners. If this is the root of your problem, you will encounter short cycling and a furnace error code indicating the pressure switch was triggered. 

An Expert HVAC technician from Service Experts Heating, Air Conditioning & Plumbing can look up 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 produce, so you will still need a pro to assist you. 

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 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. 

*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.