• In this video, This Old House plumbing and heating expert Richard Trethewey explains how to install a water heater shut-off valve.


    1 Turn off the water to the water heater.
    2 Drain the water heater using an electric pump and garden hose.
    3 Shut off the gas, then disconnect the gas line from the water heater.
    4 Cut cold-water pipe leading to heater using a tubing cutter; repeat for hot-water pipe.
    5 Disconnect flue from top of heater.
    6 Lift heater, slide catch pan underneath, then set heater back down.
    7 Reconnect gas line, after applying pipe dope to threads.
    8 Screw the flue back onto heater.
    9 Reconnect the hot-water pipe by soldering on a repair coupling.
    10 Extend the overflow pipe with copper tubing down to catch pan.
    11 Solder a copper union onto a threaded adapter; thread the adapter onto the automatic shut-off valve.
    12 Solder a second threaded adapter onto the cold-water pipe.
    13 Use tubing cutter to cut away enough cold-water pipe to install the shut-off valve.
    14 Install shut-off valve to the cold-water pipe.
    15 Plug sensor into valve; place float in water pan.
    16 Turn the gas and water back on.
    17 Test the valve by turning on the heater and manually raising the float valve; the heater should automatically shut off.
    • Difficulty: Moderate
      Installing the new valve requires completely disconnecting the water heater, and then lifting it off the floor

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      Video Directory

      Selected Topic/Section

      Tools List

      • tubing cutter
        Tubing cutter
        for cutting copper tubing
      • propane torch
        Propane torch
        for soldering together copper tubing
      • wrench
      • Phillips screwdriver
      • needlenose pliers

      Shopping List

      1. Automatic shut-off valve with water sensor

      2. Catch pan, used to catch water leaks

      3. Copper tubing and assorted fittings

      4. Lead-free solder
      5. Flux
      applied to copper joints prior to soldering

      6. Emery cloth
      used to clean copper tubing prior to soldering

      7. Garden hose

      8. Pipe dope
      applied to threads of gas union

      9. Nylon cable ties
      for attaching the sensor wire to the overflow pipe