• In this how-to video, This Old House plumbing and heating contractor Richard Trethewey prevents trapped air from stopping a heating system cold in its tracks.


    1. Turn off water leading to the boiler.
    2. Mark the pipe for cutting, which allows the installation of the air valve.
    3. Use reciprocating saw to cut out section of pipe.
    4. Install copper threaded adapters to each side of the air valve.
    5. Solder the air valve to the pipe.
    6. Turn the water back on.
    7. Switch on circulator pump to allow trapped air to escape through the valve.
    • Difficulty: Moderate to hard
      Professional installation is recommended

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      Video Directory

      Selected Topic/Section

      Tools List

      • reciprocating saw
        Reciprocating saw
      • propane torch
        Propane torch
      • tubing cutter
        Tubing cutter,
        used to cut copper tubing
      • adjustable wrench
        Adjustable wrench,
        used to install threaded adapters to air valve

      Shopping List

      1. Air valve

      2. Copper threaded adapters
      for attaching air valve to existing copper pipe

      3. Emery cloth
      used to clean outside of pipe ends prior to soldering 4. Flux

      5. Lead-free solder

      6. Teflon pipe tape