expansion tank - diaphragm or bladder?

Discussion in 'Water Heater Forum, Tanks' started by grantZab, Jul 24, 2009.

  1. grantZab

    grantZab New Member

    Jul 7, 2009
    I just noticed that the 6 month old expansion tank in my system is heavily corroded around the inlet. Looks like the connector is made of steel, and not stainless or brass. So I figured I'd replace it, since they're relatively inexpensive. It's an "American Water Heaters" AET-5 (5 gallon).

    Looking around for a new one, I see that there are both diaphragm types, and bladder types, and ASME and non-ASME types. The bladder types seem to be considerably more expensive. Is there any reason to use the bladder type? Most of the smaller ones seem to be non-ASME rated. Should this be a concern?
    My mains pressure is about 65 psi.

    Any recommendations for a specific brand, or are the all pretty much the same?
  2. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    They both work the same. An ASME tank will be built to more rigid specifications and may last longer, but the cost will usually reflect the better construction.
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