pex for shw systems

ws9876
ws9876 Solar Expert Posts: 448 ✭✭✭
in Energy Use & Conservation #1
is there a PEX that is good for the water tubes in a solar hot water system??? the ones that go up to the panel and then back to the exchanger...
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Re: pex for shw systems

    I'm sure there is, but as temps go up, PEX pressure ability goes down. And some PEX is insulated, and you MUST be sure it's UV rated. Unprotected PEX breaks down in a couple weeks.
    CPVC is better for heated water. you may need to have copper or stainless stubs coming out from the heater so you are not connecting the plastic right to the hot metal.
    And depending on your system, you may need PEX with an internal oxygen barrier, since it's porous to atmospheric oxygen.
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  • DavidOH
    DavidOH Solar Expert Posts: 112 ✭✭✭
    #3
    Re: pex for shw systems

    PEX makes tubing for floor heating systems. It's for higher temperatures.
    http://www.homedepot.com/p/SharkBite-1-2-in-x-1000-ft-Oxygen-Barrier-PEX-Pipe-U860O1000/202033045?N=5yc1vZbuya
    Another source: http://www.pexuniverse.com/barrier-pex-tubing

    I was thinking of using my leftover (Red) for a solar water heater also, but NOT for the coil in the sun, just the supply/return lines.
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  • Iceni John
    Iceni John Solar Expert Posts: 103 ✭✭
    #4
    Re: pex for shw systems

    I've run 1/2" PEX up to the roof of my bus to supply some quick-connect water outlets for washing my solar panels and to make feeds to and from my eventual water heating panels, and wherever it's exposed I put it inside 3/4" flexible aluminum conduit to keep the sunlight off it. You'll have to twist the conduit to spring it to a slightly larger diameter so the PEX can slide inside, but otherwise it should work just fine to protect the PEX from UV and physical damage.

    John

    40' Crown bus with 2kW of tiltable panels on the roof:

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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #5
    Re: pex for shw systems

    As Mike said, copper stubs are the standard way to keep the high heat of a non-circulating panel away from PEX.

    I am available for custom hardware/firmware development

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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,904 ✭✭✭✭✭✭
    #6
    Re: pex for shw systems

    There is a reason that the pumps are made of bronze or cast iron. The system has to survive 250F water/pressure if something goes wrong or it is unused. Use copper and your system will last and not leak. It certainly does not cost much more as most domestic solar hot water systems are less than 50 feet from the collector to the tank. Hot water can be dangerous!
    jonr wrote: »
    As Mike said, copper stubs are the standard way to keep the high heat of a non-circulating panel away from PEX.
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