Expansion Tank Installation

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Roccoo, Dec 2, 2009.

  1. Roccoo

    Roccoo New Member

    Nov 30, 2009
    I want to replace my tank.I keep seeing people say first put a brass tee fitting into the cold water line.I don't have that right now what I have is adapter fitting;because my cold water line where the tank is connected is too big for the tank to go straight in on its own.Is it a problem if I don't have a brass tee fitting and would that be better?
  2. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    I'm not sure I follow exactly what your question is, but maybe this will answer it. The way an expansion tank is installed is with a tee in the cold water line between the PRV and water heater. The tank needs to be supported well, but can be vertical (hanging down) or horizontal. In other words, there is quite a bit of leeway on just where it ends up. From the tee in the water line, there is a copper fitting that comes with the tank that makes the transition, one side screws into the tank and the other side is designed to go into a 1/2" tee. If your tee is larger, then you have to reduce the portion of the tee that goes to the tank. You can use additional 1/2" pipe to position the tank as described above. I would also recommend a ball valve between the tank and the tee to isolate the tank if needed to install a new tank someday.
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  4. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    I have never received any fitting with the tanks I buy, and our water lines are all 3/4" so a 1/2" fitting of any kind would be useless.
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