Why Your Furnace Has a Strange Smell

As the weather gets colder and you swap from cooling to heating your home, some homeowners are worried about unusual furnace smells filling the air. Find out what the most common furnace smells could mean and how proactive you should be about each one.

The Furnace Smells Musty

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

A clogged air filter can harbor mold, so getting rid of the smell can be as easy as getting a new filter. If that doesn't help, the AC evaporator coil fastened near the furnace may be the root of the problem. This component gathers condensation, which will sometimes stimulate mold growth. You’ll need a professional’s help to inspect and clean the evaporator coil. When all else fails, take a look at investing in air duct cleaning. This service removes hidden mold, regardless of where it’s growing in your ventilation.

The Furnace Smells Like Rotten Eggs

This is one of the most nerve-wracking furnace smells because it frequently implies a gas leak. The utility company adds a particular substance called mercaptan to the natural gas supply to make leaks easier to notice.

If you detect a rotten egg smell around your furnace or originating from your air ducts, shut down the heater straightaway. If you know where the main gas supply valve is, shut that off also. Then, get out of the house and dial 911, as well as your gas company. Don’t go back in 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 standing close to the furnace, this could mean the heat exchanger has cracked. This essential component contains combustion fumes, like carbon monoxide, so a cracked heat exchanger could pump unsafe levels of CO gas into your home.

Carbon monoxide poisoning has the potential to be fatal, so shut off your furnace as soon as possible 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 family's safety going forward, see to it that you have working CO detectors on each floor of your home.

The Furnace Smells Dusty

When you turn on the furnace for the first time every fall, you can expect a dusty odor to show up for a brief moment. This is the smell of six months’ worth of dust burning away as the furnace wakes up. As long as the smell dissipates within 24 hours, 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 to the exterior. A smoky smell can 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 get in touch with a professional as soon as you can to schedule a repair.

The Furnace Smell Resembles Burning Plastic

Overheating and melting electrical components are the most plausible reason for a burning plastic smell to come from your furnace. A malfunctioning fan motor is another possibility. If you don’t address the problem, an electrical fire could start, or your furnace could experience irreparable damage. Turn off the heating system right away and call an HVAC technician for help identifying and repairing this weird furnace smell.

The Furnace Has an Oily Smell

If you own an oil furnace, you could pick up on this odor when the oil filter becomes blocked up. Try replacing it to see if that resolves the problem. If the smell persists for more than a day after completing this step, it could imply an oil leak. You'll be better off with help from an HVAC professional to address this problem.

The Furnace Smells Like Sewer Odors

Sewer gas smells very similar to rotting eggs, so first eliminate the likelihood of a natural gas leak. If that’s not the problem, your home's sewer lines might have an issue, such as a dry trap or sewer leak. Flush water down the drains, including the basement floor drain, to refresh dried-out sewer traps. If the smell lingers, you’ll need to 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 assess and repair your furnace. At Service Experts Heating & Air Conditioning, we deliver thorough diagnostic services to identify the problem before the work begins. Then, we recommend the most viable, cost-effective repairs, alongside an up-front estimate for every option. Our ACE-certified technicians can resolve 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 office today.

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