Why Your Furnace Has a Strange Smell

As the weather cools down and you transition from cooling to heating your home, you may be worried about strange furnace smells filling the air. Learn what the most common furnace smells could mean and how worried you should be about each one.

The Furnace Smells Musty

Musty furnace smells usually suggest mold growth hiding in the HVAC system. To avoid subjecting your family to these microorganisms, handle this problem as soon as possible.

A wet air filter can encourage mold, so getting rid of the smell might be as straightforward as replacing the filter. If that doesn't help, the AC evaporator coil placed near the furnace could be to blame. This component accumulates condensation, which can trigger mold growth. You’ll need a professional’s help to check and clean the evaporator coil. When this still doesn't help, consider requesting air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your ductwork.

The Furnace Smells Like Rotten Eggs

This is one of the most nerve-wracking furnace smells because it probably indicates a gas leak. The utility company adds a special substance known as mercaptan to the natural gas supply to make leaks easier to notice.

If you notice a rotten egg smell near your furnace or originating from your ductwork, shut down the heater immediately. If you know where the main gas supply valve is located, shut that off too. Then, get out of the house and call 911, as well as 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 close to the furnace, this might mean the heat exchanger has cracked. This vital component safely contains combustion fumes, including carbon monoxide, so a crack may spew unsafe levels of CO gas into your home.

Carbon monoxide poisoning can be deadly, so switch off your furnace immediately if you notice a sour odor. Then, reach out to an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is the culprit. For your family's safety going forward, ensure you have reliable CO detectors on every floor of your home.

The Furnace Smells Dusty

When you start the furnace for the first time each fall, you probably expect a dusty odor to appear for a little while. 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 24 hours, 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 up and out of your home. A smoky smell will sometimes mean the flue is clogged, and now fumes are flowing back into your home. The odor might eventually reach 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 request furnace repair.

The Furnace Smell Resembles Burning Plastic

Overheating and burned electrical components are the most plausible reason for a burning plastic smell to make an appearance. A malfunctioning fan motor is another possibility. If you don’t address the problem, an electrical fire might start, or your furnace could experience irreparable damage. Shut off the heating system as soon as possible and contact an HVAC technician for help troubleshooting and repairing this unpleasant furnace smell.

The Furnace Has an Oily Smell

If you use an oil furnace, you could pick up on this stench when the oil filter becomes clogged. Try replacing it to find out if that addresses the problem. If the smell remains for more than 24 hours after taking care of this step, it may suggest an oil leak. You’ll need help from an HVAC expert to handle this problem.

The Furnace Reeks of Sewer Odors

Sewer gas smells pretty similar to rotting eggs, so first determine the potential for a natural gas leak. If that’s not the source, the sewer lines might have an issue, such as a dry trap or sewer leak. Flush water down all your drains, including the basement floor drain, to replenish dried-up sewer traps. If the smell persists, go ahead and contact a sewer line repair company.

Contact Service Experts Heating & Air Conditioning for Furnace Repair

If you're still unsure, get in touch with an HVAC technician to examine and repair your furnace. At Service Experts Heating & Air Conditioning, we deliver thorough diagnostic services to determine the problem before we figure out the best solution. Then, we encourage the most viable, cost-effective repairs, along with an up-front estimate for each option. Our ACE-certified technicians can manage 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 office today.