Five Furnace Smells and What They Mean

Did you kick on your furnace for the first time this season and discover an unpleasant odor? Oftentimes, a slight smell isn’t cause for concern, but some aromas should spark alarm bells. How do you know what to watch for or what to ignore? We’re sharing five furnace smells and if they are worry worthy.

Rotten Eggs

If you furnace smells like rotten eggs or sulfur, this indicates a problem with the gas. No matter how faint or strong the smell may be, it is in your best interest to call your gas company or an HVAC professional to see if there is a possible gas leak. There are serious health hazards associated with gas leaks including, but not limited to, nausea, fatigue, headaches, and difficulty breathing. Because a potential gas leak can be incredibly risky, we do not recommend investigating this problem on your own.

Metallic Smell

We all know the smell; machinery starts to get too hot and suddenly, the odor of metal permeates through your home. This smell should not be ignored. If you smell hot metal, it could be an indicator that your furnace is overheating. Other causes for a metallic smell emanating from your furnace could be damaged rubber parts, singed wires, or melted parts. To avoid overheating your furnace, if you smell anything metallic coming from your vents, turn off your system and call an HVAC professional.


Think you smell something like formaldehyde? Don’t ignore it. A chemical smell could mean your furnace’s heat exchanger is cracked. This is incredibly dangerous for two reasons. A cracked heat exchanger can fill your home with carbon monoxide or could potentially cause a house fire. If you smell chemicals coming from your furnace, shut down the system immediately and call Moore Home Services as soon as possible.


Are you smelling something musty coming from your vents? Don’t ignore it. A musty smell means your ductwork may have a mold infestation. Though it may not seem like a big deal, mold can be incredibly harmful to anyone living in your house. For people sensitive to mold, exposure can lead to eye, nose, and throat irritation, wheezing, or itchy skin. If you smell mold coming from your furnace, you need to schedule an appointment with a technician who will diagnose, and if necessary, properly clean and sanitize your ducts.

Burning Dust

Oftentimes, when you start your furnace for the first time, a sharp smell of burning dust is present. Though it may seem alarming, the smell of burning dust is nothing to worry about. After a season of laying dormant, dust, dander, and other buildup can get stuck in the furnace; the dust smell is your furnace burning through the buildup. This smell shouldn’t last long, if it does, you may need to change your air filter. If you feel uncomfortable changing the air filter by yourself, contact a service representative at Moore Home Services to schedule an appointment with one of our friendly technicians.

If you are experiencing any of these odors in your home or want to schedule a furnace tune-up and professional cleaning, call Moore Home Services. Our skilled technicians are ready to help you with any of your furnace needs, no matter the smell.