Why Your Furnace Has a Strange Smell

As the weather turns cold and you swap 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 proactive you should be about them.

The Furnace Smells Musty

Musty furnace odors usually indicate mold growth someplace in the HVAC system. To avoid subjecting your family to mold and mildew spores, handle this problem as soon as possible.

A wet air filter can harbor mold, so eliminating the smell might be as easy 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 can induce mold growth. You'll be better off with a professional’s help to inspect and clean the evaporator coil. When this still doesn't help, consider requesting air duct cleaning. This service eliminates hidden mold, regardless of where it's hiding in your ventilation.

The Furnace Smells Like Rotten Eggs

This is one of the most worrisome furnace smells due to the fact that it probably suggests a gas leak. The utility company puts in a useful 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 air ducts, switch off the heater immediately. If you know where the main gas supply valve is, shut that off as well. Then, evacuate your home and contact 911, followed by your gas company. Don’t reenter 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 is cracked. This vital component houses combustion fumes, including carbon monoxide, so a cracked heat exchanger could pump unsafe levels of CO gas into your home.

Carbon monoxide poisoning can be lethal, so switch off your furnace immediately if you recognize 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 continued safety going forward, see to it that you have working CO detectors on all floors of your home.

The Furnace Smells Dusty

When you fire up the furnace for the first time after a while, you probably expect a dusty odor to fill the house for a little while. This is the smell of six months’ worth of dust burning off as the furnace wakes up. As long as the smell dissipates within a 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 can mean the flue is blocked, and now fumes are settling back into your home. The odor might eventually reach the entire house, jeopardizing your family’s health if you ignore it. So switch off the furnace and call a professional as soon as you can to schedule a repair.

The Furnace Smells Like It's Burning Plastic

Overheating and melted electrical components are the most common reason for a burning plastic smell to make an appearance. A failing fan motor is another possibility. 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 as soon as possible and call an HVAC technician for help diagnosing and repairing this weird furnace smell.

The Furnace Has an Oily Smell

If you have an oil furnace, you might detect this odor when the oil filter becomes clogged. Try replacing it to find out if that fixes the problem. If the smell remains for more than 24 hours after taking care of this step, it might indicate an oil leak. You’ll need help from an HVAC specialist to address this problem.

The Furnace Reeks of Sewer Odors

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

Contact A-PLUS Service Experts for Furnace Repair

If you're still unsure, call an HVAC technician to assess and repair your furnace. At A-PLUS Service Experts, we offer complete diagnostic services to pinpoint the problem before repairs begin. Then, we recommend the most viable, cost-effective repairs, along with an up-front estimate for every option. 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 A-PLUS Service Experts office today.

chat now widget box