4 Common Causes Of Burning Odors In Furnaces

When you turn on your furnace on a chilly day, you only want the reliable warmth that you've come to expect. What you don't want is to suddenly smell a burning odor that eventually overwhelms the room and quite possibly your entire home. Fortunately, it's not a sign that your furnace has suddenly caught fire, but you shouldn't waste any time having your furnace checked out by a seasoned professional.

In the meantime, you can use your own troubleshooting skills to pinpoint the cause. Here are a few common culprits when it comes to burning odors produced by your furnace.


If this is the first time you've used your furnace in months, then the aroma of burning dust is to be expected. The heat exchanger and other components have likely received a light coating of dust during the months your furnace has gone unused. That thin layer of dust and debris will burn off shortly after the furnace is started.

The aroma of burning dust will eventually fade over the course of a few days, perhaps even sooner if you use your furnace heavily. If the odor fails to dissipate within that time, you'll need your HVAC technician to take a closer look at your furnace as soon as possible.


The acrid smell of burning plastic can get almost anyone's immediate attention. Since there are very few, if any, plastic parts inside your furnace, the culprit is most likely a foreign object dropped inside of the unit or something stored in its close proximity.

If you smell burning plastic, shut off your furnace immediately and check the surrounding area for any melted or burning objects. Make sure upholstery and drapes are kept far away from any HVAC registers. If you don't see any immediate causes, have your HVAC technician perform a more thorough inspection.

Electrical Wiring

Your furnace's electrical wiring can also go haywire, resulting in an acrid odor that's more metallic in nature than burning plastic. Excessive current draw and electrical overloading caused by faulty circuits and furnace components can cause this issue. Frayed wiring can also lead to overheating, and if left unchecked, a potential fire hazard.

Most furnaces will have an automatic shutdown feature to prevent electrical overheating issues and minimize the risk of fire. Nevertheless, you should immediately cut power to the furnace and call your HVAC technician if you ever smell an electrical burning odor.

Heating Oil

A minor spill or leak can cause an oil-fired furnace to burn off its heating oil, resulting in an oily, smoky aroma that wouldn't be out of place at a barbecue or near your fireplace. Nevertheless, oil leaks and spills can be exceptionally dangerous. If you suddenly smell the aroma of burning heating oil, immediately shut down your furnace until the cause of the leak or spill can be pinpointed.

For more information, reach out to companies like Washam Plumbing Heating & Air Conditioning