March 5, 2021
 | 
By Mark Paup

Why Is That Smell Coming From My Furnace?

Updated January 18, 2024

If you have been using the same furnace for years, you may be detecting odd smells coming from your system. However, some furnace smells are fairly normal, while others indicate you could have a serious problem on your hands. If you have ever asked yourself, “why is that smell coming from my furnace”, keep reading for the answers you need, and remember that for all your furnace repair and replacement needs, you can always count on our experts at Golden Rule.

Top 5 Furnace Smells

  1. Sulfur/Rotten Eggs: That sulfuric, rotten egg-like smell coming from your furnace is something you want to be concerned about, because it may be the result of a gas leak. While natural gas is a great fuel source for a furnace, due to its high combustibility and general energy efficiency, it can also be extremely dangerous if a leak occurs. Watch out for other signs this is happening, like symptoms such as nausea, headaches, confusion, and dizziness. If you detect a natural gas leak coming from your furnace, make sure you avoid anything in your home that could be flammable and get your family out of the house ASAP.
  2. Gym/Dirty Sock Smell: The odor that you smell when you step into a locker room, that smell of sweat and dirty socks, is the result of moisture and bacteria accumulation. You may notice the same smell in your furnace when excessive condensation occurs, usually because the thermostat has been frequently turned up and down, causing condensation to form on the coils. Call a technician for thorough cleaning if you pick up this stench coming from your system.
  3. Diesel Fuel: Although furnaces don’t run on the same type of diesel you would put in your car, the fuel sources may smell similar if you use an oil-based system. When there is too much oil in your furnace, fog can form. This fog will burn when it interacts with your heating element, leading to that diesel odor you are smelling. Be careful of putting too much oil in your furnace, as this can turn it into a fire risk, and always call a technician if you smell burning in your furnace, since this may force you to repair or replace your entire system. And speaking of burning…
  4. Electrical Burning: When your furnace’s fan blower starts to age, it may consume more electricity, causing sparking in your system. The smell this results in is similar to the odor you will notice when dealing with burnt wiring. A sparking fan blower can cause damage to your system’s wiring and insulation, in addition to posing a fire risk to your whole home, so do not hesitate to give us a call if you smell burning coming from your unit.
  5. Dust/Must: If your furnace has been shut off for months, just accumulating dust, you may notice a musty odor appear in your house when you then turn your furnace back on. This smell is all the dust and debris in the system being burnt up. While there technically isn’t anything dangerous about this issue, it is a good idea to change your system’s filter if you detect this smell, as it will help improve your furnace’s efficiency and strengthen your indoor air quality. You can also avoid having to deal with this odor every winter season by calling an HVAC professional for some annual maintenance.

To schedule furnace service today, call Golden Rule at 515-393-4526 or click here to send us a message online.

Contact Us Today for Furnace Service!


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