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rework closed loop to drainback

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catbird
catbird Member Posts: 1
currently have closed loop system with 5 4'x8' collectors fed by hartell solar coupled pump. need best pump option for 8' head, solar driven if possible, in drainback setup.

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  • SWEI
    SWEI Member Posts: 7,356
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    8 feet of head

    is right on the edge for a Laing Thermotech D5 http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/BR-20A.pdf
  • hot_rod
    hot_rod Member Posts: 22,246
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    Lower the lift head

    By raising the drainback tank as high as possible Those DC solar pumps are not available in a wide selection
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • matt_sunwaysolar
    matt_sunwaysolar Member Posts: 61
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    marchpump.com

    March Pump has some of the highest head ratings that I have seen in 12V and 24V powered pumps. I believe the 809-HS model has the most appropriate capabilities.



    It is probably true the most important thing can do is to decrease the height that fluid has travel vertically.



    With 8' of head at 5gpm, you can run an 115V circulator at about 80 watts max. (Less if you use a variable speed controller.) Something like the grundfos up15-58fc.
  • hot_rod
    hot_rod Member Posts: 22,246
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    ECM circs

    are another option if you have 120V. Maybe pump that system with17W on the Alpha.



    On dual pump, high lift head, drain back I have paired and Alpha with a 15-58. Start the siphon with both running and drop back to the Alpha at speed 1 or 2.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream