Why Your Furnace Has a Strange Smell

As the weather cools down and you switch from cooling to heating your home, you might be worried about strange furnace smells floating in the air. Learn what the most common furnace smells mean and how worried you should be about each one.

The Furnace Smells Musty

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

A clogged air filter can encourage mold, so eliminating the smell could be as straightforward as swapping out filter. If that fails to remove the smell, the AC evaporator coil placed near the furnace may be the culprit. This component collects condensation, which can 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 investing in air duct cleaning. This service cleans away hidden mold, no matter where it’s growing in your ductwork.

The Furnace Smells Like Spoiled Eggs

This is one of the most concerning furnace smells because it frequently indicates a gas leak. The utility company adds a special substance known as mercaptan to the natural gas supply to make leaks more easily detected.

If you detect a rotten egg smell near your furnace or out of your air ducts, shut down the heater straightaway. If you can find where the main gas supply valve is, shut that off also. Then, get out of the house and call 911, followed by your gas company. Don’t enter the house until a professional confirms it’s safe.

The Furnace Has a Sour Stench

If you notice a sour smell that stings your nose while standing close to the furnace, this might mean the heat exchanger cracked open. This essential component safely contains combustion fumes, such as carbon monoxide, so cracks might allow unsafe levels of CO gas into your home.

Carbon monoxide poisoning has the potential to be deadly, so switch off your furnace right away 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 responsible. For your continued safety going forward, ensure you have functional CO detectors on all floors of your home.

The Furnace Smells Dusty

When you start the furnace for the first time each fall, you should expect a dusty odor to show up for a brief moment. 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 goes away within one day, you don'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 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 may permeate the entire house, risking your family’s health if you ignore it. So turn off the furnace and contact a professional as soon as you can to arrange for 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 faulty fan motor is another common cause. If you don’t correct the problem, an electrical fire may start, or your furnace could end up with irreparable damage. Shut 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 use an oil furnace, you may notice this odor if the oil filter becomes clogged. Try replacing it to see if that addresses the problem. If the smell remains for more than a day after carrying out this step, it could suggest an oil leak. You'll be better off with help from an HVAC specialist to address this problem.

The Furnace Smell Resembles Sewer Odors

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

Contact Service Experts Heating & Air Conditioning for Furnace Repair

If you're still unsure, contact an HVAC technician to assess and repair your furnace. At Service Experts Heating & Air Conditioning, we offer thorough diagnostic services to identify the problem before the work begins. Then, we encourage the most viable, cost-effective repairs, alongside an up-front estimate for all options. Our ACE-certified technicians can resolve 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 Service Experts Heating & Air Conditioning office today.