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

Using a smart thermostat isn’t just smart for spending less on heating costs. 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 let you know if it detects 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 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 switches on for a brief period of time then switches off. This HVAC game of red light, green light prevents 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 require replacement sooner. 

Without Furnace Heads Up, you might not notice your furnace is turning on and off frequently, since its blower fan might keep going. This feature can detect power interruptions that occur during short cycling. 

How Do I Keep My Furnace from Short Cycling? 

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

Replace Your Air Filter Often 

If your air filter is too dirty, it will restrict airflow. Your furnace will then shut off prematurely to avoid 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 setting up a Filter Reminder on your thermostat. 

If you’ve changed 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 bring up the Quick View menu, where you’ll select “settings” and then “equipment.” 

• The thermostat will display the wires linked 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 give you the results when it’s finished. 

Google says if the filter is clean or if your furnace didn’t pass the test, something else could be awry 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 tell if there’s a problem by paying attention to your furnace as it turns on. 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 need 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 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 detect a flame, it’s usually due to the fact it’s dirty or faulty. Your furnace will then shut off as a safety measure. If your furnace is short cycling, you’ll observe 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 coating of carbon on the surface. Cleaning a dirty flame sensor will end the short cycling problem. This job 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 breaking 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 blocked 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 deadly situation. 

However, modern furnaces are equipped with a pressure switch that generally will prevent these situations from occurring. 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’s accessible by tiny 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 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 read the error codes furnace manufacturers create, 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 expertise 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 request your appointment, contact 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.