• In this how-to video, This Old House chimney expert Mark Schaub improves the draw of a faulty water-heater exhaust pipe.

    Steps:

    1. Check the draw of water-heater exhaust pipe with a long fireplace match.
    2. From roof, inspect the top of the chimney.
    3. Use silicone caulk to cement a stainless-steel cap to top of fireplace flue.
    4. Add flue tile extension to top of water heater flue; secure the tile with silicone caulk.
    5. Drop weighted string down the water heater flue to helper in basement.
    6. Tie string to corrugated chimney liner and have helper pull string as you feed the liner down the flue from above.
    7. Seal the upper end of the liner to the top of the water-heater flue.
    8. From the basement, connect corrugated liner to the exhaust pipe leading to water heater.
    • Difficulty: Moderate to hard
      Requires climbing onto roof and modifying double-flue chimney; professional installation recommended
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      Tools List

      • caulk gun
        Caulking gun,
        used to apply silicone caulk
      • Nut screwdriver
        Screwdriver,
        used to disconnect old exhaust pipe from water heater

      Shopping List

      1. Corrugated 4-inch-diameter stainless steel chimney liner with cap,

      is inserted into water heater flue



      2. Stainless steel chimney cap,

      used to top off fireplace flue



      3. Flue tile,

      used to extend water heater flue several inches higher than fireplace flue



      4. Silicone caulk,

      used to seal flue tile to top of water heater flue



      5. Weighted nylon string,

      used to fish corrugated liner down flue