How to Clean Furnace Air Ducts

By Gene and Katie Hamilton

Tools Required
  • Shop vacuum
  • Chimney brush
  • Screwdriver
Materials Required
  • Drop cloths
  • Duct foil tape
  • Filter

Before You Begin

A licensed duct specialist inserts a power-driven rotary brush that works itself all the way from the heat registers to the main trunk line. You can do a partial cleaning using a shop vacuum. But you can only clean as far as the vacuum hose can reach, so it's not nearly as effective as having a professional do the job.

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  • Step 1 : Remove registers

    Remove registers

    Carefully remove registers by lifting the metal edges away from the wall or floor and pull them out and away. Some may be held in place with screws so a screwdriver is needed to remove them.

  • Step 2 : Remove duct screws

    Remove duct screws

    The hose of a standard shop vacuum is not long enough to reach all parts of the dust system. To gain access to sections that can't be reached remove the sheet metal screws near a convenient joint of the ducting and pull the joint apart.

  • Step 3 : Clean out the interior

    Use a chimney brush to scour the inner surface or the ducts and remove the debris with a shop vacuum. The crevice tool will be the most effective attachment to use.

  • Step 4 : Reach into panned-off returns

    The heaviest accumulation of dirt and dust is in the return air ducts or panned-off returns that are joist spaces covered with sheet metal. To access these ducts remove the staples or tacks holding the sheet metal to the wood joists and peel it back so you can clean the area. When finished, reattach the sheet metal and close any gaps with foil tape.

  • Step 5 : Repair any holes

    If you find any gaps or holes in the ducting, repair them by applying duct tape to the open joints and cracks.

  • Step 6 : Change the filter

    Change the filter Change the filter

    Change the furnace filter at least four times a year, more if you have pets or if someone in the house has allergies.