Why Your Furnace Has a Strange Smell

As the weather gets colder and you transition from cooling to heating your home, you may be worried about unusual furnace smells floating in the air. Find out what the most common furnace smells could suggest and how concerned you should be about each one. 

The Furnace Smells Musty 

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

A clogged air filter can lead to mold, so eliminating the smell can be as easy as swapping out filter. If that doesn’t help, the AC evaporator coil fastened near the furnace may be the root of the problem. This component gathers condensation, which could induce mold growth. You’ll want a professional’s help to inspect and clean the evaporator coil. When this still doesn’t help, take a look at requesting air duct cleaning. This service removes hidden mold, no matter where it’s growing in your air ducts. 

The Furnace Smells Like Rotting Eggs 

This is one of the most worrisome furnace smells since it frequently implies 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 notice a rotten egg smell close to your furnace or coming from your vents, switch off the heater immediately. If you know where the main gas supply valve is placed, shut that off also. Then, leave the house and dial 911, followed by your gas company. Don’t reenter the house until a professional confirms it’s safe. 

The Furnace Has a Sour Stench 

If you notice a sour smell that stings your nose while standing close to64} the furnace, this might mean the heat exchanger cracked open. This important component safely contains68} combustion fumes, including carbon monoxide, so a cracked heat exchanger may allow unsafe levels of CO gas into your home. 

Carbon monoxide poisoning has the potential to be fatal, so shut off your furnace immediately 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 family’s safety going forward, make sure you have functional CO detectors on each floor of your home. 

The Furnace Smells Dusty 

When you start the furnace for the first time every fall, you can expect a dusty odor to appear 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 disperses within a day, 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 safely out of your home. A smoky smell could 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 neglect it. So switch off the furnace and get in touch with a professional right away to arrange for repair. 

The Furnace Smell Resembles Burning Plastic 

Overheating and melting electrical components are the most likely reason for a burning plastic smell to appear. A faulty fan motor is another possibility. If you don’t address the problem, an electrical fire may start, or your furnace could suffer from irreparable damage. Disable the heating system immediately and contact an HVAC technician for help diagnosing and repairing this unpleasant furnace smell. 

The Furnace Has an Oily Smell 

If you have an oil furnace, you could pick up on this stench whenever the oil filter becomes blocked up. Try replacing it to see if that fixes the problem. If the smell remains for more than 24 hours after taking care of this step, it may imply an oil leak. You’ll be better off with help from an HVAC professional to handle this problem. 

The Furnace Reeks of Sewer Odors 

Sewer gas smells pretty similar to rotten eggs, so first eliminate the potential for a natural gas leak. If that’s not the problem, your sewer lines might have an issue, such as a dry trap or sewer leak. Pour water down all your drains, including the basement floor drain, to fill dry sewer traps. If the smell persists, you’ll need to contact a sewer line repair company. 

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

When in doubt, call an HVAC technician to assess and repair your furnace. At Service Experts Heating, Air Conditioning & Plumbing, we deliver comprehensive diagnostic services to pinpoint the problem before repairs begin. Then, we suggest the most viable, cost-effective repairs, along with an up-front estimate for each option. Our ACE-certified technicians can handle 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. 

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