Why Your Furnace Has a Strange Smell

As the weather cools down and you swap from cooling to heating your home, you might be worried about strange furnace smells filling the air. Find out what the most common furnace smells could mean and how proactive 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 these microorganisms, address this problem as soon as possible.

A clogged air filter can harbor mold, so wiping out the smell might be as easy as replacing the filter. If that doesn’t work, the AC evaporator coil placed near the furnace could be the root of the problem. This component gathers condensation, which could trigger mold growth. You'll want a professional’s help to inspect and clean the evaporator coil. When the problem still won't go away, take a look at scheduling air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your air ducts.

The Furnace Smells Like Spoiled Eggs

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

If you notice a rotten egg smell close to your furnace or coming from your air ducts, shut down the heater straightaway. If you know where the main gas supply valve is located, shut that off also. Then, evacuate your home and call 911, as well as your gas company. Don’t enter the house until a professional tells you it’s safe.

The Furnace Has a Sour Stench

If you detect a sour smell that stings your nose while close to the furnace, this may mean the heat exchanger is cracked. This important component houses combustion fumes, including carbon monoxide, so a cracked heat exchanger could spew unsafe levels of CO gas into your home.

Carbon monoxide poisoning could be deadly, so turn off your furnace as soon as possible if you detect 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 health and safety going forward, see to it that you have reliable CO detectors on each floor of your home.

The Furnace Smells Dusty

When you fire up the furnace for the first time every fall, you can expect a dusty odor to fill the house for a brief moment. This is the smell of six months’ worth of dust burning up as the furnace wakes up. As long as the smell dissipates 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 backed up, and now fumes are flowing back into your home. The odor may permeate the entire house, endangering your family’s health if you ignore it. So switch off the furnace and contact a professional straightaway to request furnace repair.

The Furnace Smells Like It's Burning Plastic

Overheating and burned electrical components are the most likely reason for a burning plastic smell to make an appearance. A failing 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. Shut off the heating system right away and contact an HVAC technician for help identifying and repairing this weird furnace smell.

The Furnace Has an Oily Smell

If you use an oil furnace, you might detect this odor if the oil filter becomes blocked up. Try replacing it to see if that resolves the problem. If the smell lingers for more than a day after completing this step, it could suggest an oil leak. You’ll need help from an HVAC specialist to fix this problem.

The Furnace Reeks of Sewer Odors

Sewer gas smells pretty similar to rotten eggs, so first rule out the potential for a natural gas leak. If that’s not the issue, the sewer lines might have an issue, like a dry trap or sewer leak. Pour water down the drains, including the basement floor drain, to replenish dried-out sewer traps. If the smell sticks around, you’ll need to contact a sewer line repair company.

Contact Wesley Wood Service Experts for Furnace Repair

If you're still unsure, contact an HVAC technician to check and repair your furnace. At Wesley Wood Service Experts, we deliver complete diagnostic services to determine the problem before the work begins. Then, we encourage the most viable, cost-effective repairs, along with an up-front estimate for all options. Our ACE-certified technicians can handle just about any heating problem, and we back our work with a 100% satisfaction guarantee for one year. For details about why your furnace smells bad or to request furnace repair near you, please contact your local Wesley Wood Service Experts office today.