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How many times can PEX freeze before bursting?

HeatingHelp
HeatingHelp Administrator Posts: 679
edited December 2017 in THE MAIN WALL
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How many times can PEX freeze before bursting?

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Alan Welch

Comments

  • imtools
    imtools Member Posts: 6
    I'd like to know the durability of PEX-AL-PEX in a slab as I just put 2000' of it in a 6" garage slab. I am assuming that I should use anti-freeze running thru a heat exchanger off my boiler but is this all necessary?
  • HomerJSmith
    HomerJSmith Member Posts: 2,635
    I hope it wasn't one big loop. Why did you use PEX-AL-PEX instead of plain ole pex with an 02 barrier?

    Encased in concrete, I would think it wouldn't matter.

    "Is it necessary", it depends.

  • Jamie Hall
    Jamie Hall Member Posts: 24,837
    The weakest spot is the fittings. Properly made up crimp rings, probably not to worry. Sharkbites? Maybe not so good.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • LMacNevin
    LMacNevin Member Posts: 16
    Good discussion, and great timing. PPI just released a Technical Report on this topic: PPI TR-52 "Resistance of PEX Pipe and Tubing to Breakage When Frozen (Freeze-break Resistance)" includes all the information that we could find on this subject, including the NREL research that Jay Burch mentioned.
    And while PEX usually does withstand freezing without breakage, a frozen pipe flows no water, so it's best to prevent all pipes from getting cold enough to freeze. TR-52 has advice on that too.
    The announcement: https://plasticpipe.org/pdf/bcd-announcement-tr-52.pdf
    Direct link: https://plasticpipe.org/pdf/tr-52-2020.pdf

    Also, The Build Show did a neat episode on this topic a while back. https://buildshownetwork.com/blogs/copper-vs-pex-freeze-test-part-2?page=19
  • tocker
    tocker Member Posts: 31
    I'm not as concerned about freezing, but heat. In replacing my old CI boiler and piping, I'm considering Uponor HePEX installed home-run between the panel radiators and the manifolds. I've had a few contractors (there are very few in this area) in to provide estimates, but none recommend using Uponor. One said that the system would probably get too hot. I'm planning to have panels large enough to lower AWT to around 140 (max 170?). Should I spec PEX-AL-PEX instead?
  • pecmsg
    pecmsg Member Posts: 5,290
    tocker said:

    I'm not as concerned about freezing, but heat. In replacing my old CI boiler and piping, I'm considering Uponor HePEX installed home-run between the panel radiators and the manifolds. I've had a few contractors (there are very few in this area) in to provide estimates, but none recommend using Uponor. One said that the system would probably get too hot. I'm planning to have panels large enough to lower AWT to around 140 (max 170?). Should I spec PEX-AL-PEX instead?

    Why such a High Temperature? That eliminates a condensing boiler!

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