What could be causing the burning smell in your home’s heat ducts and vents?

There could be several reasons why you have a burning smell coming from your heat vents.  The answer could be something as simple as burning dust to a faulty heater component. I will discuss these in depth below.

The most common reason you might experience a burning smell when you first turn on your heat for the season is that dust has settled on your furnace heat exchanger.  The heat exchanger of your furnace gets extremely hot when it operates and this heat will “burn” any dust that has accumulated on the parts over the summer months. This is a good indicator of the buildup of dust that is occurring inside the system.  The dust in the heat exchanger will burn off but in order to remove the dirty buildup inside the ducts you must have them vacuumed out by a professional air duct cleaner. Be sure to call a reputable company that is certified by the NADCA (National Air Duct Cleaners Association) which sets industry standards and cleaning procedure guidelines.

Though the most common reason is dust in the duct work, there are several other reasons why you might notice a burning smell when your heat comes on. Be sure to check the top of the heat exchanger for debris that may have fallen into the duct work during construction or at another time when your registers might have been off: these items could be smoldering and cause an odor.  Also, if you have a heat pump, check the electric heat kit for a wiring short, debris that may have fallen on top of it, or other problems. When electrical shorts occur in your heat pump or furnace, the wiring can melt the insulators or wires. This has a smoky smell to it and may signify a problem.  Be sure to call a qualified technician to check your system.

The blower section of your furnace collects dust over the summer while it is not in use.  This should be cleaned and the meter should be oiled (if applicable to the particular unit) so it runs smoother, quieter and more efficiently.   Additionally, make sure that the chimney of your furnace is free and clear; sometimes during the warmer summer months birds or rodents make nests in the chimney.  Leaves or twigs might also make their way in and cause a blockage. It is important that this is cleared out by the homeowner or a professional chimney sweep for the furnace to function properly.  While you are checking the other parts of your system, don’t forget to check your furnace filter. See if it is blocked. If the airflow is restricted enough it can cause resistance heaters, motors, and controls to overheat and possibly burn out.

6 Responses to What could be causing the burning smell in your home’s heat ducts and vents?

  • joyce says:

    Our Trane XL20I has been emitting an ashy odor off and on since June.
    We have called a techncian but we still have the problem.
    Do you have any idea what could be causing this ashy and acrid
    odor to permeate our house?

    • admin says:

      There are many reasons why an odor can occur in duct work. A dead animal could emit a very strong odor and must be removed and the area must be properly sanitized. You mentioned that you started to notice the smell in June. Do you have central air conditioning and did the smell start when you started to use it? This could mean your air conditioning coils which are located inside your furnace need to be cleaned.

      If you are able to pinpoint an area in your home where the odor is more intense, Advanced can scope the duct work to actually see what is going on inside the duct work.

      Proper sanitation and deodorizing with the correct products is very important as odors can be very difficult to remove.

  • joyce small says:

    We have a Trane heating and cooling unit in one with
    an outdoor unit and a unit also in our basement.
    When a unit is serviced for the coming season..would
    they have cleaned the coils without us asking them
    to as part of their routine?
    The odor is pretty intense in our living room..
    Back in November it was very strong and I had
    to open my front door to air it out.
    it also is in our den and our bedroom.
    We have had this unit for 5 years and last summer
    was the first time we experienced this problem.
    I thought it would go away when the weather got
    cold but no such luck.

    • admin says:


      A company probably would not clean coils without your request because this is a timely process and quite expensive service. It may be that there is mold in the air handler. Another possibility is rodent urine. When the weather starts getting cold rodents try to find somewhere warm to live and end up in ductwork. When rodents go into the ductwork, they will urinate in the ducts causing a very strong odor. Please give us a call at your convenience and we will try to help you solve the problem you are having. We are in the office from 8:00-6:00 Monday to Friday & 8:00-2:00 on Saturday.

  • will says:

    I have a trane furnace . Ive all of a sudden for the past 2 days been experiencing a strong ashy smell at First I thought the smell was coming from my chimney but later found out It was coming from the Vent . I do have to admit that my filter is dirty so tomorrow morning I will take a trip to Lowes and replace the filter . I doubt that this will resolve my issue
    can you help me with this , ?

    • admin says:

      There are several reasons why you could smell a burning or “ashy” smell from your vents when your heat comes on. It could be something as simple as dust particles burning off the heat exchanger to a faulty component in your furnace.

      While dust is the most common reason for a smell of that kind, you could have an electrical short causing wire to melt. There could be an excess of debris in the burner area of your furnace. You can never go wrong by having a qualified HVAC technician check out your furnace.

      You mentioned the filter was very dirty. This is an indication of dust in the duct work. A dirty filter also restricts airflow enough to cause motors and controls to overheat and possible burnout. A clean filter is imperative to the proper operation of your furnace.

      Give us a call at 877-437-3742 for a free estimate for a complete duct cleaning!

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