Unusual Reasons Your Furnace Won’t Engage

In a previous blog, we talked about several reasons why your HVAC system won’t turn on. As a follow-up to that topic, there are several lesser-known, but still, equally important reasons why your furnace won’t engage. Here are the top four to keep in mind if you experience a problem with your system.

There’s a problem with the power supply
As we mentioned in that blog, one reason could be that you’ve tripped a breaker. However, power problems can extend beyond that with your furnace. Older homes with dated electrical panels may still be operating on a fuse-based system. As power demands grow for the modern household, it’s possible that your home simply needs an electrical upgrade.

Likewise, there could be a problem with your blower capacitor. This unit has a built-in tolerance level. If it can’t start the blower, then the furnace won’t engage. 

There’s a blockage in your intake vent
Depending on your furnace set up, it may have an intake vent. This happens when a conventional furnace is in an area that may prevent it from utilizing the air already in your home. In this case, fresh air from the outside is brought in and mixed with the recycled air from your return air vents. 
If this is blocked, your furnace won’t engage. What are some common reasons this could be blocked? Snow and ice are often the primary culprits. For example, the massive cold weather system that enveloped most of the country around Christmas of 2022 caused some of these vents to be clogged with snow at the mouth. Simply clearing the obstruction (and adding a layer of mesh to the opening) is enough to cause the system to reengage.

Your app is “broken”
Another less common but equally frustrating reason your furnace won’t engage may be completely out of your control. Some smart thermostats require access to the internet for your smartphones to communicate with your HVAC system. If your internet service provider has an outage, simply hopping off of your WiFi network may be all you need to do.

However, the thermostat manufacturer themselves also will have some kind of app that connects to their servers. Sometimes, they will run maintenance that will cause an outage. In other cases, they may have a problem at the server level that prevents communication with your HVAC system. Your furnace won’t engage because it’s not receiving the commands from the app.

The way to test this is to physically walk over to your furnace and turn it on. If it works, you know it’s an app-based problem and not your thermostat itself.

You’re burning too much gas
A fourth reason why your furnace won’t engage is if you’re burning too much gas.

“But wait, don’t I burn more gas when it’s cold outside?”
True, you do. However, all furnaces have calibration settings that control the volume of gas they burn in relation to the temperature. If your calibration settings are off, and your system is burning more than it should, the furnace won’t engage as a means of protecting itself.

Let us know how we can help
Each of these four reasons why your furnace won’t engage can be frustrating. Some of these will require the assistance of a trained professional. If you have concerns about your furnace, let us know. You can call us at (801) 980-0903 or send us a message HERE requesting an appointment.

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