Why Your Furnace Has a Strange Smell

As the weather turns cold and you switch from cooling to heating your home, some homeowners are worried about strange furnace smells in the air. Learn what the most common furnace smells could mean and how worried you should be about each one. 

The Furnace Smells Musty 

Musty furnace odors almost always indicate mold growth someplace in the HVAC system. To avoid exposing your family to these microorganisms, address this problem as quickly as possible. 

A wet air filter can harbor mold, so getting rid of the smell can be as simple as replacing the filter. If that fails to remove the smell, the AC evaporator coil mounted near the furnace could be the culprit. This component accumulates condensation, which could stimulate mold growth. You’ll need a professional’s help to inspect and clean the evaporator coil. When this still doesn’t help, consider scheduling air duct cleaning. This service cleans away hidden mold, regardless of where it’s growing in your ventilation. 

The Furnace Smells Like Rotting Eggs 

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

If you recognize a rotten egg smell close to your furnace or coming from your ductwork, shut down the heater right away. If you can find where the main gas supply valve is, shut that off as well. Then, evacuate your home and call 911, followed by 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 discover a sour smell that stings your nose while standing near64} the furnace, this may mean the heat exchanger cracked open. This important component safely contains68} combustion fumes, like carbon monoxide, so cracks might spew unsafe levels of CO gas into your home. 

Carbon monoxide poisoning could be lethal, so shut off your furnace right away if you recognize 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, ensure you have reliable CO detectors on all floors of your home. 

The Furnace Smells Dusty 

When you fire up the furnace for the first time after a while, you probably expect a dusty odor to show up for a brief moment. This is the smell of six months’ worth of dust burning off 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 clogged, and now fumes are settling back into your home. The odor can reach through the entire house, risking your family’s health if you ignore it. So switch off the furnace and contact a professional as soon as you can to schedule a repair. 

The Furnace Smell Resembles Burning Plastic 

Overheating and melted electrical components are the most common reason for a burning plastic smell to appear. A malfunctioning fan motor is another possibility. If you don’t tackle the problem, an electrical fire could start, or your furnace could end up with irreparable damage. Shut off the heating system right away and call an HVAC technician for help troubleshooting and repairing this weird furnace smell. 

The Furnace Has an Oily Smell 

If you have an oil furnace, you might pick up on this stench when the oil filter becomes clogged. Try replacing it to determine if that resolves the problem. If the smell lingers for more than one day after completing this step, it may imply an oil leak. You should get help from an HVAC expert to address this problem. 

The Furnace Smell Resembles Sewer Odors 

Sewer gas smells pretty similar to rotting eggs, so first rule out the possibility of a natural gas leak. If that’s not the issue, your home’s sewer lines might have an issue, for example a dry trap or sewer leak. Pour water down all your drains, including the basement floor drain, to refresh dry sewer traps. If the smell persists, 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 assess and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we perform complete diagnostic services to identify the problem before the work begins. Then, we encourage the most viable, cost-effective repairs, along with an up-front estimate for every option. Our ACE-certified technicians can handle just about any heating repair, and we back our work with a 100% satisfaction guarantee for one year. For details 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.