What’s That Scent Coming From My Furnace?

Nov 16, 2018 | Furnace

Studio shot of a young woman holding her nose isolated on white

If your furnace is producing a strange scent, you should always treat it with caution. While the cause for the odor may be benign, it could just as easily be harmful to inhale. When in doubt, always open windows to ensure ventilation, and evacuate your home.

For your convenience and protection, our Conway Comfort Heating & Cooling team developed a list of five common furnace scents and what they mean:

1. Burnt Plastic

If you just turned on your furnace for the winter, your nostrils may detect a burning scent. If this is the case, you don’t need to panic yet. Furnaces collect dust over time, which is burnt off when you first turn on your furnace. It might be a good idea to check your filter to see if it needs replacing. However, if the scent doesn’t dissipate after about 30 minutes, contact one of our HVAC technicians to check it out.

2. Rotten eggs

The sulfuric rotten-eggs scent usually points to a natural gas leak. Gas distributors often give it this scent in order to tip you off when a leak occurs, since gas is typically odorless. If you believe there is a natural gas leak, open your doors and windows, then be sure everyone gets out of the house to safety. From there, you should call 911, as well as your gas company.

3. Musty and/or Mildewy

This scent is usually indicative of dirty ducts. Over time, your ductwork becomes overrun with dust, debris, mildew, and mold. Ventilation carries this scent around the house. Not only is this scent unpleasant; it’s bad for your indoor air quality (IAQ). To solve the scent issue, have your ducts cleaned by a professional.

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4. Metallic and/or Electric

This is likely the scent of your motor overheating. In this case, it’s a good decision to power down your furnace immediately. Then, schedule a repair with one of our professional technicians.

5. Formaldehyde

If you can smell a pungent chemical scent similar to formaldehyde, this presumably means you have a cracked heat exchanger. You should evacuate immediately and call 911. Cracked heat exchangers are known to release carbon monoxide (CO) fumes that are potentially lethal when inhaled.

Our team at Conway Comfort Heating & Cooling hopes you found this list of common furnace scents useful! Remember, always treat chemical scents with the utmost wariness. Call us at 609-371-4822 here in Monroe Township, NJ, or any of its surrounding areas with any additional questions or to schedule service.

Need HVAC Service?

Call Us at 609-371-4822
- or -


Conway Comfort Heating & Cooling services Monroe Township, East Windsor, Princeton, Allentown, Bordentown, Cranbury, Dayton, East Brunswick, Ewing, Hamilton, Hightstown, Hillsborough, Jamesburg, Lawrenceville, Montgomery, North Brunswick, Pennington, South Brunswick, Newton, Yardley, and the surrounding New Jersey and Pennsylvania communities with their heating and cooling needs. Visit our service area page for more coverage details, call us at 609-371-4822 or request service online today.

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