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Buffer+Expansion tank?

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nicholas bonham-carter
nicholas bonham-carter Member Posts: 8,578
in THE MAIN WALL
Reading this excellent, well written article:
http://www.pmmag.com/articles/96765-alternate-methods-to-pipe-a-buffer-tank
I wonder if the expansion tank, and buffer tank could not be one and the same. If it used the old school technology of no diaphragm, with an air space above the water, would it not be more convenient, and with no rubber barrier to fail?--NBC

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  • hot_rod
    hot_rod Member Posts: 22,226
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    Sure, I run my shop system with a an old 160 gallon LP tank in a vertical position.

    The top has about about 12" air space. Solar drainback pumps from the tank, then it feeds to a HTP solar Phoenix coil as the is an air source. DHW is from a plate HX on the Phoenix.

    My wood boiler also connects into the tank also.

    The critical detail is all air vents MUST pipe into that air bubble, or you eventually start to lose the air bubble.

    I made that mistake, had an AutoFill and a Discal air purger connected to the system, lost some of the air bubble and froze several of the solar collectors as they did not drain back when they lost access to that air bubble to break the siphon.

    Get one of those glass sight glass kits for any tank that you want to keep an air bubble in. Or clear pex tube, like Uponor makes a nice sight tube.

    Also that air space needs to be large enough to handle expansion, and it ends up being much larger than a diaphragm tank "size"

    The Wessels website still has a free sizer program for non diaphragm type compression thanks. And the Amtrol Handbook has the sizing math.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    zavnet

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