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

Having a smart thermostat isn’t just smart for spending less on heating costs. It can also let you know if there’s a problem with your furnace. 

The Google Nest has a function called Furnace Heads Up, which will alert you if it detects a problem 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 common 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,” that means 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 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 more quickly. 

Without Furnace Heads Up, you might not notice your furnace is turning on and off frequently, because 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 Often 

If your air filter is too dirty, it will limit airflow. Your furnace will then shut down prematurely to avoid overheating. We recommend changing flat filters once a month, and pleated filters every three months. It’s easy to stay on top of changing 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 do a test to see if that repairs the problem. 

• Press the ring to pull 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 shown. Hit “test.” 
• Choose “Furnace Heads Up” and follow the instructions. Your furnace will run a 15-minute heating check and tell 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 awry that needs professional help. If this happens, contact Service Experts Heating & Air Conditioning at 954-736-4314 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 starts up. Here’s what to check 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 have to remove the door for this. 
• Turn on the furnace by setting the thermostat to a warmer indoor temperature. 
• When you switch 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 because it’s dirty or faulty. 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 few 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 layer of carbon on the surface. Cleaning a dirty flame sensor will end the short cycling issue. This job is best left to an Expert. That’s due to the fact an HVAC professional like Service Experts Heating & Air Conditioning 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 outside 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 plugged, it can cause your furnace to overheat. 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 occurring. Households with small children will often find their kids have stuffed 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 trigger 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 root 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 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 require 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, 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 request your appointment, call us at 954-736-4314 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.