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 an issue with your furnace. 

The Google Nest has a feature called Furnace Heads Up, which will alert you if it detects 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 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 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 turns on for a short period of time then turns 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 likely to break 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 running. This feature can pick up on 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 prevent your furnace from short cycling. 

Change Your Air Filter Regularly 

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

If you’ve changed your filter after getting a Furnace Heads Up alert, you can do 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 show the wires connected to it. Select “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 test 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 wrong that requires professional help. If this happens, call Aramendia Plumbing, Heating and Air at 210-404-4233 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 tell if there’s a problem by watching your furnace as it turns on. 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. 
• Turn 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 hot enough, the gas will turn on and the burners will ignite. 
• If the flame sensor can’t sense a flame, it’s usually because it’s dirty or faulty. Your furnace will then turn off as a safety measure. If your furnace is short cycling, you’ll notice the flame and fan shutting off after a few seconds. 

If you’re wondering how flame sensors could get dirty being bathed in fire constantly, a combination 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 issue. This task is best left to an Expert. That’s because an HVAC professional like Aramendia Plumbing, Heating and Air 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 Often 

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 make sure it’s always clear. If the pipe gets blocked, 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 young 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 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 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 Aramendia Plumbing, Heating and Air can look up the codes for you and determine the problem. Unfortunately, Nest has not developed 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 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 Aramendia Plumbing, Heating and Air, our Experts have the knowledge 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 book your appointment, call us at 210-404-4233 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.