Smelly Furnace? 2 Odors That Could Signal A Problem

Posted on: 14 March 2018

The furnace is a key part of your heating system, but most homeowners do not place enough emphasis on maintaining this important part of the home. While surprising, certain odors coming vents while heating could signify a problem with your furnace. By knowing these smells, you will know when and if your system needs maintenance or repairs. Here are a few odors that are stemming from an underlying issue with your furnace.


If your system uses natural gas or propane to heat your home, the smell of sulfur should be taken very seriously. The sulfur smell is often described as the smell of rotten eggs. In most cases, this smell stems from a leak in your gas lines, which can be incredibly dangerous if not repaired.

Of course, natural gas and propane are both odorless, so you may be wondering how and why you are noticing this sulfur smell.

The chemical methyl mercaptan is added to natural gas and propane to help you and professionals determine if gas is leaking. As your furnace heats, a small amount of the unburned gas is released. This will result in a rotten egg odor, but it should only last a minute or so.

If you are still noticing the odor after a few minutes or the odor is present even when your system is not heating, there is most likely a leak that needs to be addressed.


You may think a burning odor is normal while heating your home, but that is not actually true. You should never feel excessive heat that could burn you or smell odors that signal something is burning inside the system.

If you are smelling a burning odor that can be compared to melting plastic or cooking metal, your furnace's blower motor may be overheating. In these situations, it is best to turn your furnace off completely to stop the system from heating any further. Then, contact an HVAC technician to address the problem.

Replacing the blower motor will restore your furnace back to a functional and safe state. However, if the burning smell is stemming from a wiring problem, an electrician may need to inspect and repair any issues with the wiring to prevent a potential fire.

Without a functional furnace, you will not be able to heat your home in the most efficient and effective manner. If you are noticing one of these odors, it is time to have your system inspected. Check out a website like for more information and assistance.