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Expansion tank replacement

Bill H.
Bill H. Member Posts: 30
I will be replacing  my hydronic heating boiler Amtrol/extrol bladder type expansion tank. Should I fill it with water before attaching it to the system, to help force air out of that side of the bladder?


  • Slimpickins
    Slimpickins Member Posts: 330
    uh no

    Before installing the tank, check the air pressure at the schrader valve and adjust it to match whatever your system pressure needs to be, typically 12 - 15 psi. Then install it.
  • Bill H.
    Bill H. Member Posts: 30
    reply to Slimpickens

    I guess I did not clearly word my quiery. I know about adjusting the pressurized half of the tank. The side that is void except for air at atmospheric pressure, has a female fitting that will attach to my piping. My question is wouldn't putting water in that half up to the fitting purge out that air so as to not introduce same to the piping when I attach the tank? Otherwise, I suspect it will fill with water and perhaps some air when the system is put back on line.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    If you hang the tank the way it was designed....

    with the tapping facing upward, it will auto purge.

    If you pre-fill it and then install it upside down, you're going to be mighty wet before you get it screwed on ;-)

    Even if you DON'T install it in the correct position, it will work just fine. Air, in water is still compressible.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
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