• In this video, This Old House plumbing and heating contractor Richard Trethewey quiets a whistling heating duct.

    1. Mark the location of a start collar on both the return- and supply-side duct.
    2. Cut holes in each duct using a sheet metal duct cutter attached to a drill/driver.
    3. Screw a start collar to the return-side and supply-side ducts.
    4. Install elbows to each end of a bypass damper.
    5. Attach the bypass damper between the two start collars, effectively connecting the return duct to the supply duct.
    • Difficulty: Moderate
      requires basic sheet-metal working skills

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      Tools List

      • drill
        Drill/driver equipped with a sheet metal duct cutter

      Shopping List

      1. Bypass damper, used to quiet a noisy duct

      2. Start collars, for attaching bypass damper to existing duct