Why Your Furnace Has a Strange Smell

As the weather turns cold and you switch from cooling to heating your home, you might be worried about weird furnace smells floating in the air. Learn about what the most common furnace smells mean and how worried you should be about them. 

The Furnace Smells Musty 

Musty furnace odors almost always suggest mold growth hiding in the HVAC system. To avoid subjecting your family to allergy-inducing mold, address this problem as quickly as possible. 

A clogged air filter can harbor mold, so wiping out the smell could be as straightforward as getting a new filter. If that fails to remove the smell, the AC evaporator coil mounted near the furnace may be the culprit. This component gathers condensation, which will sometimes trigger mold growth. You’ll want a professional’s help to examine and clean the evaporator coil. When the problem still won’t go away, consider investing in air duct cleaning. This service removes hidden mold, no matter where it’s growing in your ductwork. 

The Furnace Smells Like Spoiled Eggs 

This is one of the most nerve-wracking furnace smells since it frequently suggests a gas leak. The utility company puts in a particular substance known as mercaptan to the natural gas supply to make leaks easier to detect. 

If you detect a rotten egg smell close to your furnace or coming from your vents, shut down the heater immediately. If you can find where the main gas supply valve is located, shut that off as well. Then, leave the house and call 911, followed by your gas company. Don’t enter the house until a professional can verify 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 may mean the heat exchanger has cracked. This important component contains68} combustion fumes, like carbon monoxide, so cracks might pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning can be lethal, so switch off your furnace immediately if you detect a sour odor. Then, contact an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is the culprit. For your health and safety going forward, make sure you have reliable CO detectors on all floors of your home. 

The Furnace Smells Dusty 

When you turn on the furnace for the first time each fall, you can expect a dusty odor to show up for a brief moment. This is the smell of six months’ worth of dust burning up as the furnace wakes from its summer slumber. As long as the smell disperses within one day, you shouldn’t have anything to worry about. 

The Furnace Has a Smoky Smell 

Natural gas, oil and propane furnaces are combustion appliances, so they vent fumes to the exterior. A smoky smell will sometimes mean the flue is blocked, and now fumes are flowing back into your home. The odor might eventually reach the entire house, endangering your family’s health if you neglect it. So switch off the furnace and call a professional right away to arrange for repair. 

The Furnace Smells Like It’s Burning Plastic 

Overheating and melting electrical components are the most likely reason for a burning plastic smell to make an appearance. A failing fan motor is also possible. If you don’t address the problem, an electrical fire may start, or your furnace could suffer from irreparable damage. Turn off the heating system right away and contact an HVAC technician for help diagnosing and repairing this unusual 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 lingers for more than a day after taking care of this step, it could indicate an oil leak. You’ll be better off with help from an HVAC professional to handle this problem. 

The Furnace Reeks of Sewer Odors 

Sewer gas smells pretty similar to spoiled eggs, so first rule out the likelihood of a natural gas leak. If that’s not the problem, the sewer lines may have an issue, such as a dry trap or sewer leak. Flush water down your own drains, including the basement floor drain, to fill dried-out sewer traps. If the smell persists, you’ll need to contact a sewer line repair company. 

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

If you’re still uncertain, call an HVAC technician to examine and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we deliver comprehensive diagnostic services to determine the problem before repairs begin. Then, we suggest the most viable, cost-effective repairs, as well as an up-front estimate for every option. Our ACE-certified technicians can handle just about any heating problem, 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.