As the weather turns cold and you swap from cooling to heating your home, you might be worried about unusual furnace smells filling the air. Learn what the most common furnace smells could mean and how concerned you should be about them.
The Furnace Smells Musty
Musty furnace odors usually imply mold growth somewhere in the HVAC system. To avoid subjecting your family to these microorganisms, address this problem right away.
A damp air filter can harbor mold, so eliminating the smell could be as easy as swapping out filter. If that fails to remove the smell, the AC evaporator coil placed near the furnace might be the root of the problem. This component accumulates condensation, which could trigger mold growth. You'll be better off with a professional’s help to inspect and clean the evaporator coil. When this still doesn't help, take a look at investing in air duct cleaning. This service removes hidden mold, regardless of where it’s growing in your air ducts.
The Furnace Smells Like Rotting Eggs
This is one of the most concerning furnace smells since it most likely suggests a gas leak. The utility company adds a special substance called 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 vents, shut off the heater immediately. If you can find where the main gas supply valve is located, shut that off also. Then, evacuate your home and call 911, followed by your gas company. Don’t enter the house until a professional can verify it’s safe.
The Furnace Has a Sour Stench
If you notice a sour smell that stings your nose while close to the furnace, this could mean the heat exchanger cracked open. This important component contains combustion fumes, including carbon monoxide, so cracks might allow unsafe levels of CO gas into your home.
Carbon monoxide poisoning can be lethal, so turn off your furnace as soon as possible if you notice a sour odor. Then, contact an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is the culprit. For your continued safety going forward, make sure 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 each fall, you can expect a dusty odor to show up 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 goes away 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 to the exterior. A smoky smell will sometimes mean the flue is blocked, and now fumes are backdrafting into your home. The odor may permeate the entire house, endangering your family’s health if you let it continue. So switch off the furnace and get in touch with a professional as soon as you can to schedule a repair.
The Furnace Smell Resembles Burning Plastic
Overheating and melting electrical components are the most likely reason for a burning plastic smell to make an appearance. A faulty fan motor is another common cause. If you don’t correct the problem, an electrical fire could start, or your furnace could experience irreparable damage. Shut off the heating system right away 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 addresses the problem. If the smell remains for more than a day after completing this step, it could 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 pretty similar to rotting eggs, so first rule out the possibility of a natural gas leak. If that’s not the source, your sewer lines could have an issue, for example a dry trap or sewer leak. Pour water down your own 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 for Furnace Repair
If you're still uncertain, call an HVAC technician to assess and repair your furnace. At Service Experts Heating & Air Conditioning, we perform complete diagnostic services to pinpoint the problem before repairs begin. Then, we encourage the most viable, cost-effective repairs, along with 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. For details about why your furnace smells bad or to request furnace repair near you, please contact your local Service Experts Heating & Air Conditioning office today.