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PEX suport requiments

Robert_H Member Posts: 141
Two questions:

1.    I have 4 tubes of PEX (ROTH PEX-Pert) running up a wall cavity to a radiant ceiling (7' height). To fix an infiltration problem I had to open the wall all the way up I have access to the pex.  Since I’m in the wall should I secure the pex or just leave it free?

2.    In general when running radiant pex around my basement to heat loads what is the minimum support spacing?


  • Ironman
    Ironman Member Posts: 7,376
    edited November 2013

    Pex-al-pex or type A or C pex?

    Pex-al-pex 8 ft. Max. Other non Al types, 32 inches max. Horizontally. Not sure on vertical, but the hotter the water, the more like spaghetti non Al pex becomes. Use good judgement.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Robert_H
    Robert_H Member Posts: 141
    PEX b

    Bob, Its PEX b.

    Thanks for replying
  • SWEI
    SWEI Member Posts: 7,356
    edited November 2013
    Buy some sections

    of steel stud track -- the stuff that goes at the bottom of the wall.  Hang it from the joists using threaded rod.  The 2-1/2" stuff will hold a pair of small insulated PEX lines just about perfectly.  Zip ties (black, UV resistant) will keep them in place.
  • Robert_H
    Robert_H Member Posts: 141
    Low Overhead

    Nice trick SWEI But I already cant stand up in most of my basement.  I don't know why they couldn't run a couple more courses of stone as there is plenty of it lying around the property!
  • Dave H_2
    Dave H_2 Member Posts: 554
    Pex Support

    Most code bodies follow what the manufacturers suggest;

    32" on the horizontal

    4 feet on the vertical.

    With that being said, check with local codes. I have run into some areas of the country where they may require different.

    Dave H.
    Dave H
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Its more than just support...

    PEX has a high coefficients of expansion. 1.1" per 100 foot length per 10 degree F change in temperature to be exact.

    So for a 2 story run, going from 70 to 140 degrees F, it will grow 1.1 X .16 X 7 = 1.25 inches. If this significant growth is allowed to go where it wants to go, then it will most probably make a lot of noise when doing so due to rubbing on floor joists etc. I like to control the direction of growth, and accommodate it to keep it as silent as possible. Anchor it on the top and bottom of the run, and leave a large loop in the middle to accept expansion and contraction, thereby keeping the tubing silent.

    Support doesn't necessarily mean "anchored". It can be a guide that allows the growing tube to glide back and forth. When I "anchor" the pipe, I am truly clamping down on it to keep it locked into that position. For example, with 3/4" PEX, I will take a 2 X 4 block, of whatever length is necessary and drill a 1" hole through the largest side of the wood. I will then cut the board in the center of the hole so I have two halves of my "clamp". I will wrap this around the PEX, and screw to halves together thereby cinching the tubing to the wood, and can then screw the clamp to the structure to anchor it. This way, I control WHERE the expansion grows to and can keep it quiet.

    Patent anyone? :-)

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Gordy
    Gordy Member Posts: 9,546
    edited November 2013
    Not a bad jig

    For a PHD Hydronicist :-)). Now why have plumbers not performed jig maneuver? Well most plumbers.
  • Robert_H
    Robert_H Member Posts: 141
    Good stuff Mark!

    The gears are turning...
This discussion has been closed.