Identifying Odd Odors From A Furnace

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If your furnace ever emits a strange odor, you might find it frustrating to try to figure out the nature of the smell. There are a number of reasons that this phenomenon can occur. It is less likely to occur when furnace maintenance is performed. Some odors are a mere nuisance or embarrassing. However, there are odors that can be a sign that there are serious mechanical or safety issues. This is why it is ideal to have a basic knowledge of what certain odors mean. The following points will identify a few common sources of offensive odors that you might notice if your furnace needs servicing. HVAC services should be called if you notice any of these smells, so they can clean your HVAC system.


You might smell a burnt odor when you turn your furnace on for the first time following the summer months. The smell is usually associated with dust burning off of the inner components of the furnace. Dust accumulation can occur when a furnace has not been in use for a while. You will smell this odor if you get your furnace serviced and also if you happen to use the furnace before annual servicing. The odor should not linger. 


If mold is present in your furnace, it is likely due to condensation encouraging the substance to grow. You will notice a peculiar musty odor when you use your furnace. Air ducts can also harbor mold and circulate the odor when the furnace is turned on. This odor will likely not go away until you get your HVAC system serviced. The service will include cleaning away contaminants such as mold and dust.

Lingering Burnt Odor

A burnt odor that does not go away could be a sign of a serious issue. You should cease operating your furnace if this occurs because it might be a sign of a failing component such as the heat exchanger. Continued operation could cause significant damages to the furnace. A furnace that overheats is prone to damaging parts and the heat exchanger is one of the most vulnerable parts when it comes to overheating. If you have an electrical furnace, the burnt smell could be a sign of an electrical malfunction. 

Rotten Eggs

This smell is associated with a gas leak and should be viewed as an emergency. It is a serious issue and the furnace should not be used if this smell is detected. It will require a professional furnace repair. This should be viewed as an HVAC emergency. There are several risks such as an explosion that could happen.

An HVAC contractor is a good resource to use when you notice odd odors emitting from your furnace.