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Whats in a buffer tank?

bill_a Member Posts: 10
Curious about buffer tank construction do they have "sealed" heat exchanger loops internally or is it one big volume inside, maybe with internal baffles or flow directions changers?


  • Jamie Hall
    Jamie Hall Member Posts: 23,635
    So far as I know, just one big tank...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • SuperJ
    SuperJ Member Posts: 609
    Just one big tank typically. Sometimes with a variety of ports for different purposes. Typically you want to try and maintain temperature stratification (minimize blending, hot at the top, cold at the bottom) to maximize exergy (usable energy).

    Don't be fooled by its simplicity though, people find ways of screwing up everything. How you pipe it, and what ports you use to do different things matters very much.
  • hot_rod
    hot_rod Member Posts: 22,468
    Many different types are available.

    A plain tank, multiple connections are helpful.
    Stainless, composite, plain steel and enameled steel are a few styles. Red brass and copper were available years ago, some stone lined are still available for more storage mass.

    Indirect tanks with internal coils, basically a heat exchangers, some have an upper and lower coil.

    Reverse indirect tanks with a bunch of copper inside for DHW heating.

    Ideally a tank with large connections 1-1/4 or larger, upper side, mid side and lower side is nice to have.

    2, 3 or 4 port piping options.

    The Germans have some "Uber" tanks with loading tubes, or mechanical loading taps to maximize stratification and return various temperatures at different layers.

    Chilled water buffer tanks may sometimes have a baffle inside to force flow thru the tank.

    Lochinvar has a Loc-temp version with a unique baffle portion at the bottom.

    A good John Siegenthaler article in the current HPAC magazine on the high tech buffers.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • bill_a
    bill_a Member Posts: 10