• In this video, This Old House plumbing and heating contractor Richard Trethewey and host Kevin O'Connor cut threads for a new air vent.

    Steps:
    1. Enlarge the existing air-vent hole in radiator with 7/16-inch-diameter high-speed steel drill bit.
    2. Put a ¼-inch tapered tap onto a ratchet wrench and cut new threads into the 7/16-inch hole.
    3. Spread pipe dope onto the threads of a -inch to ¼-inch bushing, then thread bushing into hole and tighten with a ratchet wrench.
    4. Apply very little pipe dope to the threads on the air vent and thread the vent into the bushing; hand-tighten the vent until it's in an upright position.
    • Difficulty: Easy to moderate
      Cutting threads isn't that difficult, but it takes patience and a steady hand
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      Tools List

      • drill
        Drill/driver fitted with 7/16-inch-diameter bit, for enlarging air-vent hole in radiator
      • ratchet wrench
        Ratchet wrench with ¼-inch tapered tap, used to cut new threads

      Shopping List

      -inch to ¼-inch threaded bushing, used to install new air vent to radiator

      Pipe dope, for sealing threaded fittings