Furnace Smells What They Mean and When to Call for Help

22 Jun by Will Kruse

Furnace Smells What They Mean and When to Call for Help

As the weather turns colder, many homeowners turn on their furnaces for the first time in months. While it’s normal for a furnace to emit a slight burning odor when first turned on, any other scents should be a cause for concern.

Here are some of the most common furnace smells and what they might mean for your home’s heating system.

Burning Dust

When you first turn on your furnace for the season, it’s normal to smell a faint burning odor. This is usually caused by the accumulation of dust on the furnace’s heating elements during the off-season.

As the furnace heats up, this dust burns off and emits a stench that should disappear within a few hours. However, if the burning odor persists beyond a few hours or becomes more potent, it could be a sign of a more serious issue.

Dust buildup can lead to overheating or even a fire if left unchecked. It’s important to schedule residential heating services to have your furnace inspected and cleaned to prevent any potential hazards.

Burning Plastic

If you smell a burning plastic scent coming from your furnace, it’s essential to turn off the system immediately and contact a professional for residential heating services. The presence of this odor may suggest that a plastic part inside the furnace, like a wire covering or a circuit board, is either melting or catching fire.

Continuing to run the furnace in this condition could lead to a fire or other severe damage to the heating system. Only a professional should handle this issue to ensure your family’s safety and the proper functioning of your furnace.

Rotten Eggs

Once you notice a powerful stench of spoiled eggs coming from your heating system, it is crucial to leave your house immediately and contact your gas provider or emergency assistance. This scent could indicate a gas leak, which can be extremely dangerous and potentially deadly.

Natural gas is odorless, but a distinctive sulfuric smell is added to make it easier to detect in the event of a leak. If you smell this odor, do not attempt to turn off the furnace or any appliances in your home. Instead, leave the premises immediately and call for help from a safe location.

Musty or Moldy

A musty or moldy smell coming from your furnace could indicate the presence of mold or mildew within the system. This can be caused by excess moisture within the furnace or ductwork, which can lead to the growth of mold spores.

Mold can harm your family’s health, especially those with respiratory problems such as asthma or allergies. It’s crucial to schedule residential heating services to check and clean your furnace to remove any mold or mildew within the system.

Oily Smell

The oil smell from an oil furnace is a common occurrence, especially when the furnace is first turned on after a period of inactivity. It is due to the oil burner releasing a small amount of unburned oil into the combustion chamber during the ignition process.

But if the oil smell persists or strengthens, it could indicate a problem with the furnace’s oil filter or nozzle. A clogged oil filter can cause the furnace to burn dirty oil, leading to a strong oil smell, while a damaged or worn-out nozzle can cause incomplete combustion, resulting in a sooty residue and a strong oil odor.


Furnace smells can indicate various potential issues with your home’s heating system. While some odors may be expected when first turning on the furnace for the season, any persistent or strong odors should be cause for concern. It’s vital to schedule residential heating services to maintain your furnace regularly to prevent potential hazards and keep your home’s heating system running safely and efficiently.

If you’re experiencing plumbing, heating, or cooling issues, don’t hesitate to contact L.J. Kruse Co. Our experienced professionals are ready to provide you with effective solutions and old-fashioned customer service.

With over a century of experience serving the greater bay area, you can trust us to get the job done right the first time. Contact us today to schedule an appointment for residential heating services in Berkeley, and let us take care of all your HVAC needs!

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