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clamp for pipe through floor

jrkeat Member Posts: 71
I have a 1/2" iron pipe for a hydronic system that is going up through a floor. The floor is ~2" of wood layers, so it's good for mounting. I'd like to find a clamp that surrounds the pipe that I can screw into the underside of the floor to hold the pipe in place. McMaster part 9578T29, shown below, is pretty close, but is the wrong diameter and is super expensive. Ideally, I'd like something I can put on after the pipe is installed, but am willing to settle for something like what's pictured.


  • Pipe riser clamps are usually used above the floor, but under the floor would work just as well. You'd have use some strapping to secure the clamp to the underside of the floor.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hourTwo btu/ per sq ft for degree difference for a slab
  • jrkeat
    jrkeat Member Posts: 71
    That could work. I could use a pair of flat surface brackets to hold it up pretty firmly. They're pretty long--like 8".
    EBEBRATT-Ed Member Posts: 13,440
    With the above riser clamps if they are too long you can shorten the wings by cutting them off up to the bolts

    Then you can use screws with washers through the wings to secure it to the floor
  • pecmsg
    pecmsg Member Posts: 3,878
    Before clamping it in place can I ask why?

    Generally the radiator above holds it in place or a saddle below. Clamping under the floor does not allow expansion and contraction.
  • jrkeat
    jrkeat Member Posts: 71
    edited January 2021
    pecmsg said:

    Before clamping it in place can I ask why?

    It kind of seemed like the right thing to do, but I'm happy to be talked out of it. Below the floor, I'm connecting it to some pex. So if you disconnect it from the radiator, the pipe can move easily up and down through the hole. The radiator is hung (Runtal), and immobilizing the pipe prevents you from lifting the radiator off. Maybe that's not a problem at all.

  • mattmia2
    mattmia2 Member Posts: 7,735
    You can get copper stubs with a mounting plate and a pex fitting.
    JUGHNE Member Posts: 10,571
    Below the floor if you add a 90 and 6" nipple, the nipple could be held up with a cross block 2X4 secured between joists.
    You could always raise the riser as needed as the weight is on the lower wood block. The pipe can expand and contract vertically as long as the holes are large enough to allow easy movement.
  • jrkeat
    jrkeat Member Posts: 71
    edited January 2021
    I can use a conventional split ring pipe clamp and mount it on a threaded rod to the joist 6" away.