Why Your Furnace Has a Strange Smell

As the weather gets colder and you transition from cooling to heating your home, some homeowners are worried about weird furnace smells in the air. Learn about what the most common furnace smells could suggest and how worried you should be about each one. 

The Furnace Smells Musty 

Musty furnace smells almost always imply mold growth somewhere in the HVAC system. To avoid exposing your family to allergy-inducing mold, handle this problem as quickly as possible. 

A damp air filter can harbor mold, so eliminating the smell could be as straightforward as swapping out filter. If that fails to remove the smell, the AC evaporator coil fastened near the furnace may be to blame. This component gathers condensation, which will sometimes induce 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 requesting air duct cleaning. This service removes hidden mold, regardless of where it’s growing in your ventilation. 

The Furnace Smells Like Rotting Eggs 

This is one of the most concerning furnace smells because it most likely implies a gas leak. The utility company includes a particular substance known as mercaptan to the natural gas supply to make leaks more easily detected. 

If you detect a rotten egg smell around your furnace or originating from your vents, shut off the heater right away. If you remember where the main gas supply valve is placed, shut that off as well. Then, leave the house and contact 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 standing near64} the furnace, this could mean the heat exchanger cracked open. This essential component contains68} combustion fumes, including carbon monoxide, so cracks may allow unsafe levels of CO gas into your home. 

Carbon monoxide poisoning can be fatal, so turn off your furnace immediately if you notice a sour odor. Then, contact an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is to blame. For your continued safety going forward, ensure you have functional CO detectors on every floor of your home. 

The Furnace Smells Dusty 

When you start the furnace for the first time after a while, you can expect a dusty odor to show up 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 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 backed up, and now fumes are settling back into your home. The odor may permeate the entire house, jeopardizing your family’s health if you ignore it. So shut down the furnace and call a professional right away to request furnace repair. 

The Furnace Smells Like Burning Plastic 

Overheating and burned electrical components are the most likely 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 could start, or your furnace could experience irreparable damage. Turn off the heating system as soon as possible and contact an HVAC technician for help troubleshooting and repairing this unusual furnace smell. 

The Furnace Has an Oily Smell 

If you use an oil furnace, you may pick up on this smell if the oil filter becomes clogged. Try replacing it to see if that fixes the problem. If the smell persists for more than a day after taking care of this step, it may indicate an oil leak. You’ll be better off with help from an HVAC expert to fix this problem. 

The Furnace Smell Resembles Sewer Odors 

Sewer gas smells pretty similar to rotten eggs, so first rule out the likelihood of a natural gas leak. If that’s not the problem, the sewer lines may have an issue, such as a dry trap or sewer leak. Try pouring water down all your drains, including the basement floor drain, to fill dry sewer traps. If the smell sticks around, go ahead and contact a sewer line repair company. 

Contact Service Experts Heating, Air Conditioning & Plumbing for Furnace Repair 

If you’re still uncertain, contact an HVAC technician to check and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we deliver thorough diagnostic services to determine the problem before the work begins. Then, we encourage the most viable, cost-effective repairs, alongside an up-front estimate for each 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 & Plumbing office today. 

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