Why Your Furnace Has a Strange Smell

As the weather turns cold and you transition from cooling to heating your home, you may be worried about weird furnace smells filling the air. Find out what the most common furnace smells could suggest and how proactive you should be about them. 

The Furnace Smells Musty 

Musty furnace odors generally imply mold growth somewhere in the HVAC system. To avoid subjecting your family to allergy-inducing mold, handle this problem as quickly as possible. 

A wet air filter can encourage mold, so getting rid of the smell can be as simple as swapping out filter. If that fails to remove the smell, the AC evaporator coil placed near the furnace might be the culprit. This component accumulates condensation, which could induce mold growth. You’ll want a professional’s help to check and clean the evaporator coil. When all else fails, start thinking about investing in air duct cleaning. This service eliminates hidden mold, no matter where it’s growing in your ductwork. 

The Furnace Smells Like Rotting Eggs 

This is one of the most concerning furnace smells since it probably implies a gas leak. The utility company includes a special substance known as mercaptan to the natural gas supply to make leaks easier to notice. 

If you notice a rotten egg smell around your furnace or out of your vents, switch off the heater immediately. If you know where the main gas supply valve is placed, shut that off as well. Then, leave the house and dial 911, in addition to your gas company. Don’t reenter the house until a professional tells you it’s safe. 

The Furnace Has a Sour Stench 

If you discover a sour smell that stings your nose while standing close to64} the furnace, this could mean the heat exchanger is cracked. This essential component houses68} combustion fumes, including carbon monoxide, so a crack might allow unsafe levels of CO gas into your home. 

Carbon monoxide poisoning could be fatal, so turn off your furnace right away if you detect a sour odor. Then, contact an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is to blame. For your family’s safety going forward, see to it that you have reliable CO detectors on every floor of your home. 

The Furnace Smells Dusty 

When you turn on the furnace for the first time after a while, you should expect a dusty odor to show up for a brief moment. This is the smell of six months’ worth of dust burning off as the furnace wakes from its summer slumber. As long as the smell disperses within a day, you have nothing to worry about. 

The Furnace Has a Smoky Smell 

Natural gas, oil and propane furnaces are combustion appliances, so they vent fumes safely out of your home. A smoky smell will sometimes mean the flue is blocked, and now fumes are backdrafting into your home. The odor may permeate the entire house, jeopardizing your family’s health if you neglect it. So switch off the furnace and get in touch with a professional right away to arrange for repair. 

The Furnace Smells Like Burning Plastic 

Overheating and burned electrical components are the most plausible reason for a burning plastic smell to make an appearance. A faulty fan motor is another common cause. If you don’t address the problem, an electrical fire might start, or your furnace could suffer from irreparable damage. Disable the heating system right away and contact an HVAC technician for help diagnosing and repairing this unpleasant furnace smell. 

The Furnace Has an Oily Smell 

If you have an oil furnace, you may detect this stench when the oil filter becomes clogged. Try replacing it to determine if that addresses the problem. If the smell persists for more than a day after carrying out this step, it could indicate an oil leak. You’ll be better off with help from an HVAC expert to address this problem. 

The Furnace Reeks of Sewer Odors 

Sewer gas smells pretty similar to rotting eggs, so first rule out the likelihood of a natural gas leak. If that’s not the issue, your sewer lines may have an issue, for example a dry trap or sewer leak. Try pouring water down all your drains, including the basement floor drain, to refresh dry sewer traps. If the smell sticks around, you should contact a sewer line repair company. 

Contact Service Experts Heating, Air Conditioning & Plumbing for Furnace Repair 

If you’re still unsure, call an HVAC technician to assess and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we offer complete diagnostic services to determine the problem before we figure out the best solution. Then, we recommend the most viable, cost-effective repairs, along with an up-front estimate for each option. Our ACE-certified technicians can handle just about any heating repair, and we back our work with a 100% satisfaction guarantee for one year. To ask questions about why your furnace smells bad or to request furnace repair near you, please contact your local Service Experts Heating, Air Conditioning & Plumbing office today. 

Savings For You

See All Offers Here >

$50 OFF Any Repair

  • Save $50 on a Paid Service
  • Written 100% Satisfaction Guarantee
  • Plus, ask how to save an additional 15% and waive your trip charge!
print

Make No Payments for 30 Days!

  • Upgrade to Worry-Free Comfort with the Advantage Program and make NO payments for 30 days!
print

© 2024 Service Experts, Service Experts Heating & Air Conditioning, and the Service Experts logo and design are registered trademarks of Service Experts LLC and used under license by SE Canada Inc. All Rights Reserved. *Not applicable to the Advantage Program. See your signed Advantage Program Agreement for full details and exclusions. 100% Satisfaction Guarantee is subject to certain restrictions and limitations as set forth in the applicable Terms and Conditions.