Why Your Furnace Has a Strange Smell

As the weather turns cold and you swap from cooling to heating your home, you might be worried about unusual furnace smells in the air. Find out what the most common furnace smells could suggest and how proactive you should be about each one. 

The Furnace Smells Musty 

Musty furnace odors almost always indicate mold growth somewhere in the HVAC system. To avoid subjecting your family to allergy-inducing mold, address this problem as quickly as possible. 

A damp air filter can encourage mold, so eliminating the smell could be as easy as replacing the filter. If that doesn’t work, the AC evaporator coil placed near the furnace may be the culprit. This component accumulates condensation, which can stimulate mold growth. You’ll want a professional’s help to inspect and clean the evaporator coil. When the problem still won’t go away, consider scheduling air duct cleaning. This service removes hidden mold, no matter where it’s hiding in your air ducts. 

The Furnace Smells Like Rotting Eggs 

This is one of the most nerve-wracking furnace smells because it probably implies a gas leak. The utility company includes a special substance known as mercaptan to the natural gas supply to make leaks easier to detect. 

If you notice a rotten egg smell near your furnace or out of your air ducts, shut down the heater immediately. If you remember where the main gas supply valve is, shut that off too. Then, leave the house and dial 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 discover a sour smell that stings your nose while standing near64} the furnace, this could mean the heat exchanger has cracked. This vital component houses68} combustion fumes, including carbon monoxide, so a cracked heat exchanger may pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning has the potential to be deadly, so turn off your furnace immediately if you detect a sour odor. Then, call an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is the culprit. For your continued safety going forward, ensure you have reliable CO detectors on every 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 little while. This is the smell of six months’ worth of dust burning up as the furnace wakes up. As long as the smell dissipates within 24 hours, 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 backed up, and now fumes are settling back into your home. The odor might eventually reach the entire house, risking your family’s health if you neglect it. So shut down the furnace and call a professional straightaway to arrange for repair. 

The Furnace Smells Like Burning Plastic 

Overheating and melting electrical components are the most plausible reason for a burning plastic smell to come from your furnace. A faulty fan motor is also possible. If you don’t address the problem, an electrical fire might start, or your furnace could experience irreparable damage. Shut off the heating system immediately and contact an HVAC technician for help diagnosing and repairing this unusual furnace smell. 

The Furnace Has an Oily Smell 

If you have an oil furnace, you could notice this smell whenever the oil filter becomes clogged. Try replacing it to determine if that addresses the problem. If the smell lingers for more than a day after carrying out this step, it might suggest an oil leak. You’ll need help from an HVAC expert to handle this problem. 

The Furnace Smell Resembles Sewer Odors 

Sewer gas smells very similar to spoiled eggs, so first rule out the possibility of a natural gas leak. If that’s not the source, your sewer lines may have an issue, for example a dry trap or sewer leak. Flush water down all your drains, including the basement floor drain, to replenish dried-out sewer traps. If the smell lingers, you’ll need to contact a sewer line repair company. 

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

If you’re still uncertain, call an HVAC technician to assess and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we deliver complete diagnostic services to pinpoint the problem before repairs begin. Then, we suggest 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 learn more 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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