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Any tips for installing hePex for hot water baseboard? Regarding thermal expansion.

cckriss
cckriss Member Posts: 17
edited July 2022 in Radiant Heating
I will be using 1/2” hePex. I’ve already ran 1 home run and it went pretty well. This is the longest loop at 90 feet with 12 feet of element. There are alot of bends as this is going to an addition. I used no 90 degree fittings. I used either the bend supports or it’s own natural sweep bend.

I know to leave the 90s unsupported to allow movement. Any other tips?

For the straight sections, should I stagger the clips to allow it to “snake”? I dont have the room for an expansion loop. 

I am using these clips. I paid extra attention so the pipe touches no wood framing, 


Comments

  • hot_rod
    hot_rod Member Posts: 18,208
    You have a good plan, allow movement room. Don't lay pex over pex if you can help. Yes to those clips.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • mattmia2
    mattmia2 Member Posts: 7,165
    Make sure the ends of the element are free to move too.
  • cckriss
    cckriss Member Posts: 17
    hot_rod said:
    You have a good plan, allow movement room. Don't lay pex over pex if you can help. Yes to those clips.
    What does pex over pex mean? Does that mean above each other if I were to secure them to the side of a joist?

    Going underneath joists, should I stagger the clips? To make them snake-like?
  • cckriss
    cckriss Member Posts: 17
    mattmia2 said:
    Make sure the ends of the element are free to move too.
    I drilled 1-1/8” holes for the pex risers going into the copper baseboard. I’m more concerned about the heating element lifting up off of the brackets from the pex expansion. 
  • mattmia2
    mattmia2 Member Posts: 7,165
    cckriss said:


    mattmia2 said:

    Make sure the ends of the element are free to move too.

    I drilled 1-1/8” holes for the pex risers going into the copper baseboard. I’m more concerned about the heating element lifting up off of the brackets from the pex expansion. 

    The pex itself should be able to flex enough for the baseboard to expand, just make sure the hole is lined with something that lets the tubing slip. I would use a 90 fitting under the floor instead of bending the pex at the risers for for the baseboard so that the expansion on the lateral piece of pex is isolated in the horizontal plane instead of being able to push up the curve in to the riser.
  • cckriss
    cckriss Member Posts: 17
    mattmia2 said:
    The pex itself should be able to flex enough for the baseboard to expand, just make sure the hole is lined with something that lets the tubing slip. I would use a 90 fitting under the floor instead of bending the pex at the risers for for the baseboard so that the expansion on the lateral piece of pex is isolated in the horizontal plane instead of being able to push up the curve in to the riser.
    Do you recommend using brass 90s as opposed to the black plastic ones? Because of the high temp of a hydronic heat system
  • mattmia2
    mattmia2 Member Posts: 7,165
    I'd use the EP fittings. Once you start buying more than a few brass fittings you might as well have used copper.
  • GGross
    GGross Member Posts: 395
    I second the EP fittings. The pex itself will limit your max temp in the same way EP fittings will, both are rated beyond what is needed for residential hot water heating. The one thing to note, make a list of material and check availability. EP fittings are currently still being rationed by allocation to distributors and some of us are just sitting here waiting around for truckloads of the stuff :neutral: Brass fittings tend to be readily available, and will make sense if you are transitioning to and from copper.