Pex vs copper. Which stands up better to cold?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by pitteach, Jul 12, 2010.

  1. pitteach

    pitteach New Member

    Messages:
    27
    Location:
    Hamburg, NY
    I am re-plumbing a ground floor bathroom with 2 walls that are shared with the garage. I do need to run 1/2" h/c supplies through these walls and I am not sure if I should use pex or copper. The walls are 2 x 6 with fiberglass insulation. The supplies will be wrapped in foam jackets and foam where they penetrate the studs. I do not anticipate a freezing condition, but I still want to use the material that will hold up best during temperature fluctuations. Access is not an issue and either copper or pex will be fairly easy to work with.
    The bathroom was previously done in cpvc which burst because the house sat for a while unheated during the winter.
    So the question is... which to use?
  2. North Jersey

    North Jersey New Member

    Messages:
    107
    Without a doubt, PEX. PEX can expand many times its original size without bursting. Even if the copper itself does not split, your plumbing solder will crack. Last winter our basement underwent water damage when the sweated joints failed during exceptionally cold conditions. Your fittings will still be vulnerable, but you'll be much better protected with PEX than with copper.
  3. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Copper with heat trace and insulation.
  4. North Jersey

    North Jersey New Member

    Messages:
    107
    I imagine while the house is occupied the plumbing in this bathroom would not experience freezing temperatues. If the house is going to be unoccupied, wouldn't an oil-filled electric baseboard heater with a thermostat work out a little better than heat tape? I just feel uncomfortable about having the tape inside the wall. Are my fears unfounded? If the power went out, wouldn't PEX be a little better than copper?
  5. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    If the water freezes the pex will still split and rupture. I've seen it MANY times.

    The heat trace should be 100% safe inside the wall.
  6. Terry

    Terry Administrator Staff Member

    Messages:
    15,118
    Location:
    Bothell, Washington
    The question was which pipe would be better if the power went out.

    PEX

    Copper always splts when the power goes out.
    PEX may split.
  7. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    It depends on the Pex used and several other factors.

    PEX AL PEX is not freeze resistant at all!

    PEX will normally expand and not split but the distance between brass fittings if between 2" and 7" apart PEX may split.

    This was the results of a study done several years ago in a nut shell...
  8. North Jersey

    North Jersey New Member

    Messages:
    107
    I believe the Uponor Aquapex is particularly freeze resistant since it's designed to be expanded over the fittings. It's a lot more resilient than some other stuff I tried.
  9. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Try and expand the pipe when it's freezing and not sitting at room temperature.
  10. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    No!
    Uponor PEX did experience splits in the test when fittings were 2-7" apart.
  11. North Jersey

    North Jersey New Member

    Messages:
    107
    That's why I keep all my fittings eight inches apart. :)
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