When to Worry: Furnace Smells

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Did you know that you can get hypothermia in as little as 10 to 15 minutes, even while you’re indoors? This steep drop in your core body temperature can occur if your home isn’t warm enough. A malfunctioning furnace, in turn, can render your home too cold. More than that, a faulty space heater can trigger house fires. From 2014 to 2018, heating equipment, including furnaces, was behind 4% of all house fires in the US. All that should be enough reason to pay attention to furnace smells.

To that end, we came up with this guide on the different heater smells that you may encounter. Read on to discover their causes and when they should be a cause of concern.


Dusty Smell

Outdoor dust accounts for about two-thirds of the dust you find inside your home. The rest consists of pet dander, clothes fibers and particles, and furniture fluff.

All that dust and debris can find their way into your furnace, air ducts, and vents. Those particles can then mix with the first few cycles of heated air your space heater produces.

A dusty smell from the furnace isn’t normal per se, as you can prevent this with a pre-season tune-up. However, you don’t have to panic, either, as the smell should lessen once the air pass through the filter. Just make sure you have a fresh air filter in your furnace; otherwise, that dusty smell won’t disappear.

It’s also a smart idea to get in touch with a local provider of furnace maintenance to clean your entire heater. The technician will replace the filter and clean all furnace components. For more information, visit this URL.

Short-Lived Smoky Odor

Residue build-up can also result in a burning smell from a heater. The smoky stench can come from dust and debris that your furnace actually burns away. The thicker the layer of filth, the stronger the burning-like odors can be.

Such smells should go away after an hour or so, which is enough time for the furnace to burn away all that dust. You can speed up the process by running exhaust fans, but make sure you monitor the strength of the odors. There’s no need to panic so long as they gradually become less pronounced.

Smoky Smells Don’t Disappear

If the burning stench from your furnace doesn’t dissipate after more than an hour, shut it off right away. Do the same if the odors get stronger, especially if they smell like melting plastic or rubber. Then, immediately call a local HVAC company to schedule heater repair services.

Those smells can indicate damaged or frayed electrical cords in your furnace. These are fire and electrical hazards, which is why they warrant immediate repairs.

An overheating furnace blower motor may also be behind burning plastic smells. The excessive heat can be strong enough to melt various components in the motor. The longer you let the motor overheat, the sooner it will break down completely.

So, before that happens, shut off your furnace and call a furnace repair service right away.


furnace smells


Earthy or Soil-Like Odor

This kind of furnace odor is most likely due to fungi like molds and mildew. Shut off the heater right away, as these fungi can release spores into the air when disturbed. Exposure to these spores can lead to negative respiratory and skin effects.

Contact your local heating repair company to inspect and clean your furnace.

An Odor Reminiscent of Pickles

Inside a gas furnace is a component known as the heat exchanger. It’s a thin piece of metal acting as a divider between the blower and the combustion chamber. It keeps toxic combustion gases trapped within the heating equipment.

Over time, though, the heat exchanger can develop cracks in which the toxic gases can escape. If this happens, your home may get filled with strong pickle-like odors. This stench usually originates from formaldehyde, a byproduct of combustion.

Either way, this furnace smell indicates danger, as it can lead to adverse health effects. Even short-term exposure to formaldehyde can irritate the eyes, nose, and throat. It can also induce coughing, headaches, dizziness, and nausea.

A more dangerous gas that can leak out of a cracked heat exchanger is carbon monoxide (CO). This gas is odorless, but it’s deadly and results in about 50,000 US emergency room visits every year.

Contact a furnace repair specialist as soon as you smell pickles after you turn your heater on. This way, an HVAC technician can immediately repair or replace your heat exchanger.

Rotten Egg Stench

Natural gas isn’t toxic, but it’s still an asphyxiant. This means it lessens or displaces normal oxygen in the air. People can suffocate if they stay in a room where there’s more natural gas than oxygen.

However, natural gas is odorless, so you can’t detect it without special instruments. This is why natural gas suppliers mix the gas with mercaptan, a chemical that smells like rotten eggs. Mercaptan itself is harmless, but its odors signal a potential natural gas leak.

If your furnace smells like a hot spring (which, in turn, smells like rotten eggs), turn your furnace off right away. Immediately open a few windows, grab your phone, and head straight outside. Call your utility provider to let them know about the potential gas leak.

You must go outside because one, you may suffocate indoors, and two, gas leaks can cause explosions.

Don’t Ignore Any of These Furnace Smells!


You don’t have to panic if your furnace smells dusty or it emits a short-lived smoky stench. However, it still means you need to get your heater tuned up, as these odors indicate a lack of maintenance.

Any other smell, especially burning odors that get stronger, warrants immediate professional inspection. In this case, turn off your furnace right away and contact an HVAC company immediately.

Ready for more strategies to keep your home safe, healthy, and pretty? Check out the rest of our categories for more useful guides like this!




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