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pex expansion when heated

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mikedo
mikedo Member Posts: 202
does heat pex expand like copper when heated. I'm worried about noise when used in a baseboard system if the pex is strapped tightly

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  • kcopp
    kcopp Member Posts: 4,445
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    Yes it does. In fact about 4 times as much. There is a product the Viega makes "Fostapex" that has a lower expansion rate.
    STEVEusaPAmattmia2Intplm.
  • GroundUp
    GroundUp Member Posts: 1,938
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    Pex expands 1.1" per 100 feet per 10 degree rise
    Copper expands .125" per 100 feet per 10 degree rise

    Almost 9 times as much. FostaPex was some awesome stuff, but has been discontinued. There are other brands of pex-al-pex (a layer of aluminum sandwiched between 2 layers of plastic) which would serve a very similar purpose in reducing thermal expansion.

    PAP expands .3" per 100 feet per 10 degree rise
    CLambZman
  • Jamie Hall
    Jamie Hall Member Posts: 23,536
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    As noted, it will expand. If you don't allow for the expansion --bends, joints, it will give you much grief.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    mattmia2
  • mikedo
    mikedo Member Posts: 202
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    thanks
  • Dave Carpentier
    Dave Carpentier Member Posts: 603
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    What happens inside a slab, with all those little sharpish edges against the pex ?
    30+ yrs in telecom outside plant.
    Currently in building maintenance.
  • Canucker
    Canucker Member Posts: 722
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    What happens inside a slab, with all those little sharpish edges against the pex ?
    Nothing. The pex encased in concrete doesn't move. However, it needs to be sleeved as it exits or enters the slab for the reason you're thinking of
    You can have it good, fast or cheap. Pick two
  • Dave Carpentier
    Dave Carpentier Member Posts: 603
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    Hmm, I'll have to check if we used sleeves. There's metal guide things that turned the pipes up 90deg. Im not sure if they went all the way around the pipes though.
    30+ yrs in telecom outside plant.
    Currently in building maintenance.
  • Jamie Hall
    Jamie Hall Member Posts: 23,536
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    If the PEX is totally restrained in the slab it will squish. It won't like it, but it will. Unlike copper, the forces aren't great enough to crack the slab.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England