Why Your Furnace Has a Strange Smell

As the weather cools down and you switch from cooling to heating your home, you may be worried about unusual furnace smells in the air. Find out what the most common furnace smells could mean and how worried you should be about them.

The Furnace Smells Musty

Musty furnace odors usually imply mold growth somewhere in the HVAC system. To avoid exposing your family to these microorganisms, tackle this problem right away.

A damp air filter can harbor mold, so wiping out the smell can be as simple as replacing the filter. If that fails to remove the smell, the AC evaporator coil fastened near the furnace could be the root of the problem. This component collects condensation, which will sometimes stimulate mold growth. You'll be better off with a professional’s help to check and clean the evaporator coil. When the problem still won't go away, start thinking about requesting air duct cleaning. This service removes hidden mold, no matter where it’s growing in your ventilation.

The Furnace Smells Like Spoiled Eggs

This is one of the most worrisome furnace smells due to the fact that it most likely implies a gas leak. The utility company includes a special substance called mercaptan to the natural gas supply to make leaks easier to notice.

If you notice a rotten egg smell around your furnace or originating from your ductwork, switch off the heater right away. If you know where the main gas supply valve is placed, shut that off also. Then, leave the house and call 911, followed by your gas company. Don’t go back in the house until a professional can verify it’s safe.

The Furnace Has a Sour Stench

If you detect a sour smell that stings your nose while standing near the furnace, this may mean the heat exchanger cracked open. This vital component contains combustion fumes, including carbon monoxide, so cracks could spew unsafe levels of CO gas into your home.

Carbon monoxide poisoning can be fatal, so switch off your furnace as soon as possible if you detect a sour odor. Then, call an HVAC professional for an inspection. Consider replacing your furnace if a cracked heat exchanger is to blame. For your health and safety going forward, ensure you have working 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 probably 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 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 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 ignore it. So turn off the furnace and contact a professional straightaway to request furnace repair.

The Furnace Smells Like Burning Plastic

Overheating and melting electrical components are the most plausible reason for a burning plastic smell to appear. A failing fan motor is another common cause. If you don’t address the problem, an electrical fire may start, or your furnace could experience irreparable damage. Turn off the heating system as soon as possible and contact an HVAC technician for help diagnosing and repairing this weird furnace smell.

The Furnace Has an Oily Smell

If you have an oil furnace, you might notice this stench whenever the oil filter becomes blocked up. Try replacing it to find out if that resolves the problem. If the smell persists for more than 24 hours after taking care of this step, it could suggest 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 determine the potential for a natural gas leak. If that’s not the problem, the sewer lines could have an issue, such as a dry trap or sewer leak. Flush water down all your drains, including the basement floor drain, to fill dried-up sewer traps. If the smell sticks around, you’ll need to contact a sewer line repair company.

Contact Strand Brothers Service Experts for Furnace Repair

If you're still unsure, get in touch with an HVAC technician to assess and repair your furnace. At Strand Brothers Service Experts, we offer comprehensive diagnostic services to identify the problem before the work begins. Then, we suggest the most viable, cost-effective repairs, as well as 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 Strand Brothers Service Experts office today.

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