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January 25, 2023

Furnace Smells Like Burning: What to Do

Furnace Smells Like Burning - LG Home Comfort

Have you ever noticed a burning smell coming from your furnace? It is not an uncommon issue, but it can be alarming when it happens. Fortunately, it is possible to take some simple steps to address the problem and prevent future occurrences.

This blog post will explore why a furnace smells like burning, what to do if it occurs, and the different types of burning smell from furnaces.

Reasons Why a Furnace Smells Like Burning

It can be disconcerting to come home to a home filled with the pungent aroma of something burning. It is essential to take care of this issue as soon as possible since it could indicate a bigger problem. Here are some of the causes for this smoky smell coming from your furnace:


One of the reasons your furnace smells like it’s burning is due to an accumulation of dust and debris in the filter or blower motor. The dust that builds up can cause friction when the fan runs, leading to an acrid smell.

Bacteria Buildup 

Mold, bacteria, and other microorganisms can accumulate in areas difficult to reach and clean, such as air ducts or filters. This buildup can also lead to a smoky smell coming from your furnace.


Another cause for foul-smelling smoke may come from the furnace’s electrical components that have worn down over time or become damaged due to lack of maintenance. If you suspect this is the case, it is best to call a qualified technician who can inspect and repair any necessary parts safely and effectively.

Gas Leak

A gas leak is another potential culprit for a smoky smell coming from your furnace. If you notice anything strange with how your gas appliances are working (or not working), make sure to contact your local utility company immediately for help diagnosing any problems with your gas lines before attempting any repairs yourself.

Oil Filter 

Change out oil filters regularly; if they become clogged or dirty, they produce black smoke, giving off an unpleasant odor.

Different Types of Burning Smell from a Furnace

Winter season is coming again, so turn on the furnace and heat your home. But when you do, you might be hit with some not-so-pleasant smells. Here, we will cover some of the most common types of burning smells from a furnace and explain why they occur in the first place.

Electrical Burning Smell

This burning smell originates from electrical wiring or components and is usually caused by a short circuit. Detecting an electrical burning smell could also mean an overheated blower motor due to too much use or lack of maintenance.

Rotten Egg/Natural Gas Smell

It is not normal for your furnace to smell natural gas or rotten eggs. This type of smell often indicates leaking natural gas in your home. Natural gas does not have any color or taste, so many producers add sulfur compounds, like t-butyl mercaptan, which give it a distinct rotten egg smell so you can quickly detect any leaks.

Burning Dust Smell

A burning dust smell usually occurs when you turn on your dusty furnace after not using it for a long time. When your furnace smells like burning hair or dust, the reason for this is that the dust has built up inside the unit over time, which then burns off as soon as the system turns on again.

Moldy/Musty Smell

If your furnace smells musty, it often occurs if standing water is near or around a unit that has not been dried out properly over time. This can lead to mold growth in those areas, circulating through the air whenever you turn on your system.

Burning Plastic Smell

The smell of plastic burning could indicate that a foreign object is in your heating unit. This could be anything from a plastic bottle cap to one of your children’s plastic toys. As the plastic burns from the furnace’s heat, it can emit fumes into the home that are harmful to your health.

What to Do to Prevent a Furnace Burning Smell

Fortunately, simple solutions can help you prevent a furnace burning smell from occurring as follows:

Tip #1: Regularly Replace the Air Filter

When filters become clogged with dust and debris, they put extra strain on your furnace, requiring it to work harder. This can lead to an unpleasant burning odor coming from your HVAC system. To prevent this from happening, make sure you replace your air filter regularly. Changing your air filter should be part of your regular HVAC maintenance routine.

Tip #2: Check for Natural Gas Leakage

A gas leak in your home can also cause a burning smell near or around your furnace. If you discover a strange smell from the furnace, immediately turn off the gas supply and contact a professional HVAC technician.

Tip #3: Clean Exterior Surface Before Turning It On

If you have not used your furnace in a while or have been sitting idle during summer months, you may want to thoroughly clean it before turning it back on again.

Dust and debris can accumulate on the unit’s exterior surface after being inactive for extended periods, which can cause smoke or burning odors when it is turned back on again. Make sure to clean off all excess dust and dirt before turning it on.

Tip #4: Call an HVAC Technician if the Smell Persists

If none of these steps have eliminated the burning smell, you may need professional assistance from an HVAC technician specializing in furnaces and other heating systems to diagnose and properly resolve any underlying problems with your unit.

As professionals, they strictly follow safety protocols and avoid potential damages due to prolonged usage of an improperly functioning furnace system.

Final Thoughts

The next time you smell a burning smell coming from the furnace of your heating and cooling system, don’t panic. You can take some simple steps to address and prevent this issue from occurring again.

Ensure you regularly clean and replace air filters to reduce dust buildup, have an annual HVAC inspection by a certified technician, and investigate any other potential causes of the burning scent immediately to avoid further damage or safety risks. With these tips in mind, you will be more prepared to deal with any unwanted odors from your furnace.

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