What’s that Smell When I Turn on my Furnace?

As the temperatures outside start to drop, you know it’s time to switch on the heater. But when you do, you immediately smell something like burning coming from your furnace. You wonder to yourself, “Why does my heater smell like burning plastic when I turn it on?” You start to worry that perhaps something is wrong with your furnace. Is it going to catch on fire? Is it going to fill your home with smoke?

Relax. In most cases, that burning smell coming from your furnace is nothing to worry about. In this blog post, we’ll explain the two most common reasons and one not so common reason, why heaters smell weird when they’re first turned on for the season—and how we fix the problem so you can enjoy a warm home all winter long.

We recommend that you have your furnace maintenance done annually AND by a professional certified technician. As always, SS&B Heating & Cooling is here to help you make sure your heater is ready for the Missouri winter.

Couple Common Reasons Your Heater Smells Funny

#1. Dust Buildup on the Heating Elements

If there’s a burning smell coming from your furnace, one of the most common causes is dust buildup on the heating elements. When the furnace turns on, the heated air circulates through the blower motor and pushes dust and debris into the air filter. Eventually, this dust settles on top of the heating elements. When enough dust has accumulated, it can create a burning smell – and it could cause a short circuit.

The good news is that this is not too complicated to fix:

1) Turn off the furnace at the thermostat and at the disconnect switch or circuit breaker panel.

2) Remove the access panel to gain access to the blower motor and heating elements.

3) Use a vacuum with a soft brush attachment to remove any dust from around the blower motor and heating elements. If there’s a lot of dust, it may need to be cleaned several times.

4) Check the air filters and replace them if they’re dirty.

5) Once everything is clean, put everything back together and turn on the heater at both the thermostat and disconnect switch or circuit breaker panel.

#2. Debris in Your Furnace’s Burner Assembly

Another reason your furnace might be giving off a burning smell is that there’s debris in its burner assembly—the part of your furnace where combustion actually takes place. Over time, dust, dirt, and other debris can accumulate in this area and prevent your heater from functioning properly when it starts up again after being off all summer long. And when combustion isn’t happening as it should, that can cause a burning smell. Here’s what we do to clean out your burner assembly:

1) Turn off power to the furnace at both the thermostat and disconnect switch or circuit breaker panel before any work on the HVAC system.

2) remove any panels necessary to gain access to the burners.

3) use a vacuum with a soft brush attachment or compressed air to remove any debris from around the burners.

4) once everything is clean, put everything back together again..

5) turn on power to the heater at both your thermostat and disconnect switch or circuit breaker panel..

One not so common reason… is the smell of rotten eggs!

The reason you're noticing a strong, egg-like smell coming from your furnace is because of the chemicals that have been added to let people know there's gas leaking. If this happens and it resembles what we describe as "rotten eggs" then don't wait another minute before calling for us help! This could result in fires or even explosions if not dealt with quickly enough by professionals who understand how dangerous these leaks can be. If you notice this odor coming from your heater, turn off the system immediately and call us for assistance!

A burning smell coming from your furnace when you first turn it on for the season is normal in most cases—especially if it smells like plastic. More often than not, this is caused by dust buildup on heating elements or debris in burner assemblies. These problems are not too complicated to fix. If you have any questions or concerns about why your heater smells funny when you turn it on, don't hesitate to reach out to us today, we'll be happy to help. In fact, our furnace maintenance service will go through all these checks and more!

You can see the complete walk through of our furnace maintenance service on our YouTube channel

👉 https://youtu.be/6x7fkbcjztE