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October 6, 2022

When it comes to your Marin, Sonoma, or Napa County furnace, when you need it and go to turn it on, you expect it to work. When you start to feel the warm air coming out of it, you are filled with relief that it has yet again survived another long season without being used. As the heat begins to warm up your home, you may start to notice a strange odor, and ask yourself, “What’s that smell coming from my heater”? While some smells coming from your furnace may be normal, there are some odors that may be cause for concern. We are going to review common aromas that your heater may produce and what they usually mean.

What’s That Smell Coming From my Heater?

If your furnace is producing an unpleasant odor it can not only be annoying, it can be discomforting and concerning for you and your North Bay Area home and family. While you can prepare your furnace for the fall and winter, there are still things that may cause it to produce more than just heat, and could be the reason you are sniffing around to find out what it is.

As we said, not all smells coming from your furnace are bad; however, there are some that should be cause for concern. We review some of the most common smells and their reasons below.

  • Smoky: If there is a smoky smell coming from your heater, if you have just turned on the furnace for the season; that is usually okay. The odor could just be caused by dust burning off as furnaces and ductwork commonly accumulate dust buildup when they have been dormant and unused for several months. This smell should dissipate as the dust and other particles are burned away; however, if you notice the smoky smell lingering or if the stench starts all of the sudden, there could be a larger issue. If this is the case, turn off your furnace and contact a local heating repair professional to come out and inspect your system.
  • Burning Plastic: If you are asking yourself, “What’s that smell coming from my heater?” and it is because it smells like burning plastic, that could actually be the cause. Before you turn on your furnace for the year and each time you go to use it, you should inspect around it to ensure there is nothing in it, touching it, or near to it. A burning plastic odor can be caused by a foreign object being in or near your HVAC system. If you notice this smell and can’t identify what is causing the odor, shut off your furnace and contact a local furnace repair expert as soon as possible to avoid breathing in the harmful fumes and a potential fire.
  • Musky: If your heater is producing a musty and stale odor, your air filter may be dirty and clogged. You should regularly check and change your home’s air filter to avoid this type of scenario. Air filters are one of the simplest elements of your Marin, Sonoma, and Napa County home’s heating and cooling system, but are also one of the most important. When you change your air filter frequently, it helps remove harmful particles from the air such as pollen, dust, dust mites, mold, bacteria, micro allergens and more. Removing these harmful pollutants has massive health benefits for you and your family. Plus, changing your air filter regularly helps keep your HVAC system running at its highest efficiency, which will help to lower your energy bills and extend the life of your system. With a dirty and clogged air filter, your furnace has to work much harder, and that can cause it to overheat, in turn, creating a stale smell.
  • Fishy: If there is a fishy smell coming from your furnace, it is sure to make you question what that smell is coming from your heater. The electrical components of your heating system are typically covered in chemicals and plastic. When these components heat up and/or start burning, they can produce a fishy burning odor. If you notice a burning electrical smell coming from your furnace, you should contact a HVAC professional. While furnaces are usually built to automatically power down when they start to overheat, if the safety feature is broken, this could cause issues, create the fishy smell, and put you and your family at risk of an electrical fire.


Things like professional duct cleaning, advanced air filtration systems, and an annual heating tune-up, should help you avoid less than desirable smells coming from your heater. If you have a strange odor coming from your furnace, you should always power it down and call in a professional to help.

At Bragg Plumbing & Heating we offer fast same-day HVAC service as we know you can’t be without your heat for long. Regardless of whether it is a repair or replacement, you can depend on Bragg for expert consultation that meets or exceeds your expectations. We will always give you an honest assessment of your heating situation so you can make an informed decision.

Bragg Cooling, Heating & Plumbing is a full service HVAC company that is licensed to solve all your furnace related problems, including repair, replacement, and maintenance and safety inspection. We’ve been repairing and installing furnaces since 1968. Contact us today.

We Proudly Service all Makes & Models