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Geothermal buffer tank to low temp radiant

My situation is that I have a great 80 gallon geothermal storage tank with some accessories for future use but it only has one cold inlet and one hot outlet. My thinking is that I would like to create a primary loop from the hot outlet to the cold return and install two sets of closly spaced tees off the primary loop. the first set of tees will go to the radiant panel and the second to the geothermal heatpump. I understand the hp will not be getting the coolest water in the tank but would this warrent changing to a fiur tap buffer tank.

Thanks

Comments

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Got other tappings?

    Electric element tappings? Drain cock tappings? T&T relief valve tappings?



    Whose tank is it.



    I have a design for incorporating an inlet and outlet on one tapping using concentric fittings, but the annulus is tight and flow restrictive. Heat pumps usually like LOTS of flow...



    ME
    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.
  • Renewable BTU
    Renewable BTU Member Posts: 2
    geo storage

    Thanks Mark,

    HTP tank with hx for possible future use an electric element. we could possibly use the taps for the T&P and Drain for the radiant panel although i think they are 3/4 inch. the inlet and outlet taps are 1 1/2 inch at the top of tank
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    How many Guppies Per Minute (GPM) are you pushing?

    That determines tapping size, along with anticipated delta T.



    ME
    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.
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    IF you

    pipe it like it's just a fat piece of pipe on a primary loop, and tee off that loop after the tank, then the geo will see the coldest possible return for the longest possible time... you have to heat the whole tank up before the return water starts heating up. also ensures the longest run times and longest off times... no premature mixing.



    the only downside is you MUST run the geo circulator whenever there is a heat demand. Some geo units specify real energy hogs for pumps and in those cases I opt for a 4 port buffer strategy so you can only run the geo pump when the geo is actively heating. with the 2 port strategy it must run to extract heat even when the geo compressor is turned off, so you can extract heat from the buffer tank.



    If you've got a reasonable primary loop pump though, I think it makes great sense and I think it's superior to the 4 port strategy in every other way... HOW MUCH better is very debatable, of course. which is why when the known parasitic loss of that geo circulator is high, I change strategies.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
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