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Thread: solar water heater

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  1. #1

    Question solar water heater

    I'm building my own solar water heater I need some technical advise.
    1. I will be using roof top solar panels and will need to convey the heat to the basement for storage. Is there a more cost effective 1/2" material than copper that will withstand the temperatures (200 degrees or more)
    2. What is the best insulation for the pipes
    3. The design includes a heat exchanger that will involve a concrete slab with the hot water running through ir. I I use copper, will it hold up and not corrode in the concrete? I need it to withstand the temperatures and transfer heat easily. Will Pex work?

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    Concrete and copper aren't all that great together. Pex can't handle that high of a temp, at least at higher pressures...it might work since your pressure would likely be fairly low. It gets derated as the temp goes up for the amount of pressure it can handle.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3


    Here's a good site, might be some answers?

  4. #4
    Master Plumber master plumber mark's Avatar
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    Feb 2005
    indianapolis indiana - land of the free, home of the brave....
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    Talking need more informatoin

    Their are a lot of different systems out there...

    It really depends on which type you are installing...

    Will the panels have water or antifreeze or oil going through them???

    The oil type are the best...from what I remember...Like the NOVAN style from the early 80s..

    Wirsbo pex for radiant heating under the concrete floor
    would be good..

    probably best to reveal more information or links to what you are considering doing...

    these systems are a little complicated and can be a pain if you are not capable of tinkering with them yourself...

    and some are much better than others..

    post a link to what you are looking to install...

  5. #5
    Master Plumber nhmaster's Avatar
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    Jul 2008
    S. Maine


    What is the highest anticipated temperature at the slab inlet?

  6. #6
    Computer Programmer Bill Arden's Avatar
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    Sep 2006
    MN, USA


    One thing people forget is that the higher the water temperature, the lower amount of heat you get since the system radiates heat back out of the panel.

    This means that it is best to increase the pump speed so that the water temperature is more even and as low as possible.

    FYI: The light concentrating unit we are designing reached 400F with an outdoor temp of -10F during a "dry" test a few weeks ago. However this still means that we have to run the water at a much lower temperature to capture as much heat as possible.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  7. #7
    Plumber Cass's Avatar
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    Nov 2005


    A 250' roll of K copper, unrolled on a sun exposed roof, painted flat black, with an adjustable speed recirculating pump, will work well in a non freezing area.

    You might be able to hook it into your still and pre heat the mash also...

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