Why Your Furnace Has a Strange Smell

As the weather cools down and you swap from cooling to heating your home, some homeowners are worried about unusual furnace smells in the air. Learn what the most common furnace smells mean and how proactive you should be about them.

The Furnace Smells Musty

Musty furnace smells generally imply mold growth hiding in the HVAC system. To avoid exposing your family to these microorganisms, tackle this problem as soon as possible.

A clogged air filter can harbor mold, so getting rid of the smell can be as straightforward as getting a new filter. If that doesn't help, the AC evaporator coil mounted near the furnace could be the root of the problem. This component gathers condensation, which will sometimes stimulate mold growth. You’ll need a professional’s help to check and clean the evaporator coil. When all else fails, start thinking about scheduling air duct cleaning. This service cleans away hidden mold, no matter where it's hiding in your air ducts.

The Furnace Smells Like Spoiled Eggs

This is one of the most nerve-wracking furnace smells since it frequently indicates a gas leak. The utility company puts in a useful substance known as mercaptan to the natural gas supply to make leaks easier to notice.

If you detect a rotten egg smell around your furnace or coming from your vents, switch off the heater immediately. If you know where the main gas supply valve is located, shut that off also. Then, leave the house and call 911, in addition to your gas company. Don’t enter the house until a professional can verify 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 cracked open. This vital component safely contains combustion fumes, including carbon monoxide, so cracks may allow unsafe levels of CO gas into your home.

Carbon monoxide poisoning has the potential to be lethal, so switch off your furnace immediately if you recognize a sour odor. Then, call an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is to blame. For your family's safety going forward, ensure you have functional CO detectors on each floor 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 appear for a few minutes. This is the smell of six months’ worth of dust burning away as the furnace wakes from its summer slumber. As long as the smell goes away 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 could mean the flue is backed up, and now fumes are backdrafting into your home. The odor might eventually reach the entire house, risking your family’s health if you ignore it. So switch off the furnace and contact a professional straightaway to schedule a repair.

The Furnace Smells Like Burning Plastic

Overheating and melting electrical components are the most common reason for a burning plastic smell to come from your furnace. A failing fan motor is also possible. If you don’t tackle the problem, an electrical fire may start, or your furnace could experience irreparable damage. Disable the heating system as soon as possible and contact an HVAC technician for help diagnosing and repairing this unusual furnace smell.

The Furnace Has an Oily Smell

If you own an oil furnace, you could detect this smell if the oil filter becomes clogged. Try replacing it to determine if that resolves the problem. If the smell remains for more than one day after completing this step, it might imply an oil leak. You'll be better off with help from an HVAC professional to fix this problem.

The Furnace Reeks of Sewer Odors

Sewer gas smells very similar to rotten eggs, so first eliminate the likelihood of a natural gas leak. If that’s not the issue, the sewer lines may have an issue, like a dry trap or sewer leak. Pour water down all your drains, including the basement floor drain, to fill dried-out sewer traps. If the smell lingers, go ahead and contact a sewer line repair company.

Contact Stallion Heating Plumbing Air Conditioning for Furnace Repair

If you're still uncertain, get in touch with an HVAC technician to check and repair your furnace. At Stallion Heating Plumbing Air Conditioning, we deliver comprehensive diagnostic services to pinpoint the problem before the work begins. Then, we recommend the most viable, cost-effective repairs, as well as an up-front estimate for each option. Our ACE-certified technicians can handle just about any heating malfunction, and we back our work with a 100% satisfaction guarantee for one year. To learn more about why your furnace smells bad or to request furnace repair near you, please contact your local Stallion Heating Plumbing Air Conditioning office today.

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