Brettski:
I am planning on doing the same thing (radiant heat in a shop floor) but I'm going about it a bit differently. Here's my plan and why I'm doing it this way.
My radiant heat company suggested 5/8" tube. They also suggested that because it'll be in a shop, that it should be installed directly on the foam. There is a gun that staples the tubing directly to the foam, and that is what they recommended. On advice of my concrete guy, he recommended a 5" thick slab. From what I've read, and what the radiant people preferr, is NOT to use wire mesh, use rebar instead and put it on chairs to get it in the middle of the slab and up off the tubing. My concrete guy agrees. He said #4 rebar on 2' centers, if I want to make it stronger, put them on 1' centers. They (radiant people) prefer rebar because 1)it won't be smashed into the tubing by the workers walking on it when the concrete is poured and leveled, therefore minimizing any potential punctures, 2) the tubes will stay on the bottom of the slab where they belong.
The concrete guy liked the idea because his guys wouldn't have to pull up the mesh to try and get it centered in the slab like it's supposed to, and he said that the rebar spaced that far apart would let his guys step between the bars. The radient people said that stepping on the tubes wouldn't damage them providing the workers didn't "jump up and down on them". From working with concrete out in california, in addition to the rebar or mesh, we had the fiberglass "hairs" mixed in the concrete as well. My boss said "the fibers will stop any surface cracks, but it's the steel that gives the concrete it's structural strength." I know of 2 different buildings here in Indiana that were poured that way, one with radiant heat in the floor and one without and neither of them show any signs of cracking where it wasn't supposed to crack.
So, I'm going with 5/8" O2 barrier Pex attached to the foam, #4 rebar on 2" tall chairs, 5" slab with fiber reinforced concrete.
Manifolds on the wall too. BUT, from what I've read, there aren't any UV sabilizers in the PEX tubing, so any that would be exposed to sunlight need some sort of UV protection, whether paint, inside a closet or some sort of sleeve. You know that the PEX should be in a plastic sleeve when it transitions from horizontal to vertical, right?
Last edited by esshup; 03/13/09 07:55 PM. Reason: PEX info.
