Why Your Furnace Has a Strange Smell

As the weather gets colder and you transition from cooling to heating your home, you may be worried about weird furnace smells in the air. Learn what the most common furnace smells could mean and how worried you should be about them. 

The Furnace Smells Musty 

Musty furnace odors almost always indicate mold growth someplace in the HVAC system. To avoid exposing your family to allergy-inducing mold, handle this problem as quickly as possible. 

A clogged air filter can encourage mold, so getting rid of the smell might be as straightforward as getting a new filter. If that doesn’t help, the AC evaporator coil placed near the furnace might be the root of the problem. This component gathers condensation, which can stimulate mold growth. You’ll be better off with a professional’s help to check and clean the evaporator coil. When all else fails, consider 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 because it most likely implies a gas leak. The utility company puts in a particular substance called mercaptan to the natural gas supply to make leaks easier to notice. 

If you notice a rotten egg smell around your furnace or originating from your ductwork, switch off the heater immediately. If you can find where the main gas supply valve is located, shut that off as well. Then, get out of the house and contact 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 close to64} the furnace, this could mean the heat exchanger has cracked. This important component contains68} combustion fumes, including carbon monoxide, so a crack might allow unsafe levels of CO gas into your home. 

Carbon monoxide poisoning could be lethal, so turn 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 responsible. For your continued safety going forward, ensure you have reliable CO detectors on all floors of your home. 

The Furnace Smells Dusty 

When you fire up the furnace for the first time each fall, you should expect a dusty odor to show up for a few minutes. This is the smell of six months’ worth of dust burning up as the furnace wakes up. As long as the smell dissipates 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 safely out of your home. A smoky smell could mean the flue is blocked, and now fumes are flowing back into your home. The odor can reach through the entire house, endangering your family’s health if you neglect it. So shut down the furnace and contact a professional right away to request furnace repair. 

The Furnace Smells Like It’s Burning Plastic 

Overheating and burned electrical components are the most common reason for a burning plastic smell to appear. A malfunctioning fan motor is another common cause. If you don’t correct the problem, an electrical fire may start, or your furnace could suffer from irreparable damage. Shut off the heating system as soon as possible and call an HVAC technician for help troubleshooting and repairing this unusual furnace smell. 

The Furnace Has an Oily Smell 

If you own an oil furnace, you may pick up on this odor if the oil filter becomes clogged. Try replacing it to determine if that fixes the problem. If the smell persists for more than 24 hours after carrying out this step, it could imply an oil leak. You’ll be better off with help from an HVAC expert to fix this problem. 

The Furnace Smells Like Sewer Odors 

Sewer gas smells very similar to rotten eggs, so first eliminate the possibility of a natural gas leak. If that’s not the source, your sewer lines might have an issue, like a dry trap or sewer leak. Try pouring water down your own drains, including the basement floor drain, to replenish dried-up sewer traps. If the smell lingers, you’ll need to contact a sewer line repair company. 

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

When in doubt, call an HVAC technician to examine and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we offer thorough diagnostic services to pinpoint the problem before the work begins. Then, we suggest the most viable, cost-effective repairs, as well as an up-front estimate for all options. Our ACE-certified technicians can manage just about any heating malfunction, 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.