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Considerations for expansion/contraction of PEX run along joists?

jaytav Member Posts: 3
edited March 20 in Plumbing
The hot water line shown in these pictures is expanding due to temperature increase. It's about 20 feet long.

The pipe is deflecting upwards and downwards from the straight line when it was attached. Is there any worry about abrasion in this scenario? Should there be an expansion/contraction loop at the end of this run to take up the slack instead?


  • Jamie Hall
    Jamie Hall Member Posts: 23,270
    There should indeed be an expansion loop. Further, on a hot water line, my preference has always been to lay the pipe in a trough, lying free. Otherwise, over time, it will sag.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • kcopp
    kcopp Member Posts: 4,430
    Throw a few more Talon hangers up there you will be fine. By code a hanger on pex every 30"

  • Intplm.
    Intplm. Member Posts: 1,936
    Every 18 to 24 inches is best for hanging pex. especially on the hot water piping. Usually the closer together the hangers the better.
  • hot_rod
    hot_rod Member Posts: 22,103
    The red hot would be nice to have insulated. That would save limit heat loss and handle any expansion noise. Shouldn't need and expansion loop in that short run.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,285
    A trick I've used is to cut small pieces of 3/4" plywood and use those as standoffs under the talons. This gives room for 3/4" wall insulation to go on the pipe. The PEX will move less, because of the insulation and will not rub on the wood, so should have a longer life.

    Yours, Larry