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 weird furnace smells in the air. Find out what the most common furnace smells could suggest and how worried you should be about them. 

The Furnace Smells Musty 

Musty furnace smells generally indicate mold growth hiding in the HVAC system. To avoid subjecting your family to allergy-inducing mold, address this problem as quickly as possible. 

A wet air filter can lead to mold, so getting rid of the smell might be as simple as getting a new filter. If that doesn’t work, the AC evaporator coil mounted near the furnace might be the root of the problem. This component gathers condensation, which can trigger mold growth. You’ll be better off with a professional’s help to inspect and clean the evaporator coil. When the problem still won’t go away, take a look at scheduling air duct cleaning. This service cleans away hidden mold, no matter where it’s hiding in your ventilation. 

The Furnace Smells Like Rotten Eggs 

This is one of the most nerve-wracking furnace smells since it most likely implies a gas leak. The utility company adds a particular substance known as mercaptan to the natural gas supply to make leaks easier to detect. 

If you recognize a rotten egg smell near your furnace or coming from your ductwork, switch off the heater straightaway. If you know where the main gas supply valve is placed, shut that off also. Then, leave the house and dial 911, in addition to your gas company. Don’t reenter the house until a professional can verify it’s safe. 

The Furnace Has a Sour Stench 

If you discover a sour smell that stings your nose while standing close to64} the furnace, this may mean the heat exchanger is cracked. This essential component safely contains68} combustion fumes, such as carbon monoxide, so cracks may pump unsafe levels of CO gas into your home. 

Carbon monoxide poisoning can be deadly, so shut off your furnace right away if you detect a sour odor. Then, call an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is responsible. For your continued safety going forward, make sure 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 after a while, you can expect a dusty odor to appear for a few minutes. This is the smell of six months’ worth of dust burning up as the furnace wakes from its summer slumber. 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 up and out of your home. A smoky smell can mean the flue is backed up, and now fumes are flowing back into your home. The odor may permeate the entire house, risking your family’s health if you let it continue. So switch off the furnace and contact a professional right away to schedule a repair. 

The Furnace Smells Like Burning Plastic 

Overheating and burned electrical components are the most likely reason for a burning plastic smell to make an appearance. A failing fan motor is another common cause. If you don’t tackle the problem, an electrical fire might start, or your furnace could suffer from irreparable damage. Shut off the heating system immediately and contact 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 may pick up on this stench whenever the oil filter becomes blocked up. Try replacing it to determine if that resolves the problem. If the smell remains for more than one day after completing this step, it could imply an oil leak. You’ll need help from an HVAC specialist to fix this problem. 

The Furnace Smells Like Sewer Odors 

Sewer gas smells very similar to rotting eggs, so first rule out the possibility of a natural gas leak. If that’s not the problem, your home’s sewer lines could have an issue, like a dry trap or sewer leak. Pour water down the drains, including the basement floor drain, to refresh dried-out sewer traps. If the smell persists, you should contact a sewer line repair company. 

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

If you’re still unsure, contact an HVAC technician to assess and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we perform complete diagnostic services to identify the problem before we figure out the best solution. Then, we recommend 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. 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.