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1968 Expansion tank replacement

I have an American Standard boiler, 4BN-J2, cica 1968. I would like to replace and relocate the expansion tank with a newer smaller model. How do I know how big of a tank (i.e. gallons) I need? Are there any issues concerning the replacement that I should be aware of? Thanks.


  • SWEI
    SWEI Member Posts: 7,356
    http://www.amtrol.com/support/extrol_com_sizing.html will help with the sizing. If the system has a lot of water (large diameter pipes) in it, use the commercial calculator. You can cross to a non-ASME tank with the same acceptance volume. You will also need to change your air control valve out for an air elimination device.

    That boiler is well past its wear date. Have you considered a replacement?
  • eldridgehome
    eldridgehome Member Posts: 2
    Thank you; it looks like I need the 4.4 gallon tank. I am not in a position to change out the boiler right now, but need to move the expansion tank, so a new smaller model looked like an inexpensive improvement.
  • Jamie Hall
    Jamie Hall Member Posts: 22,972
    Double check... 4.4 gallon is kind of small...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England