expantion tank location

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by livesteamr, Oct 31, 2009.

  1. livesteamr

    livesteamr New Member

    Messages:
    2
    Location:
    Boxford Massachusetts
    Simple question, does it make a difference where the expantion tank is located in a hot water system? I am tight for space near the boiler and am looking for alternative locations.
  2. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,142
    Location:
    South*East
    It can be any where in the the system as long as there are no valves between the boiler and the tank.

    John
  3. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Ideally the expansion tank would be located near the boiler with the water feeder piped in below. that is the point of zero pressure differential. the circulator (s) should be installed past the tank, pumping away from the boiler.

    www.heatinghelp.com
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,309
    Location:
    Cave Creek, Arizona
    ?

    What kind of system is it? Hot water heating, or heating domestic hot water? The location of the tank is similar for both, in that it goes after the fill/feed shut off valve to the vessel. A domestic ET goes ahead of the storage tank, and the hot water heating one usually goes right on, or after, the boiler.
  5. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    I thought he was talking about a hydronic boiler system.
    If it's a water heater the tank needs to go anywhere in the cold water line.

    For hydronic, we like to come up off the boiler then hit an air eliminator with the feed piped below it and the expansion tank just below the feeder. That arrangement keeps the feeder from overfilling the boiler should there be a pressure differential. It is important that the circulator be piped past all of this otherwise you have defeated the whole purpose. Dan Holohans "pumping away" does a nice job of describing the specifics and providing piping diagrams. For years we just slapped the tank and fill wherever we could put them, mostly because boiler came packaged with the circ on the return. Manufactures did that because they could crate and stack boiler in the warehouse more efficiently. In a small residential system it probably would never be a problem, but when you start pumping long distances or up three stories it can make a huge difference in how the system performs.
    Last edited by a moderator: Oct 31, 2009
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,309
    Location:
    Cave Creek, Arizona
    tank

    Many air eliminators have an air vent tapping on top and the expansion tank opening on the bottom.
  7. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    They sure do. I really prefer to use SpiroVent's unit.
  8. livesteamr

    livesteamr New Member

    Messages:
    2
    Location:
    Boxford Massachusetts
    expantion tank

    Thanks Guys you were a great help, the tank is now installed as in the latest reply.
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