Pex-Al-Pex vs Barrier pex with heat transfer plates

Joshua van Tol_3

I'm planning to install an infloor heat system over an existing subfloor using plywood sleepers and aluminum heat transfer plates. Hardwood will then be installed over top of this.

My question is whether Pex-Al-Pex is better in this application because of its lower thermal expansion characteristics, or whether I could use a regular oxygen barrier pex and not have expansion noises or other problems.

Also, how effective are the non-AL oxygen barriers? I would assume they are not as good, but does it matter?

Unknown

for o2 barrier, both are good enough, though AL is better.

Reducing expansion in this type of installation is a very good thing. we use only PAP in such applications these days... price differential, if any, is not enough to avoid its use. There is no really good reason NOT to, that is.

jeff_99

Kitec and Plates

There is one proviso with PAP n' Plates: don't use Kitec with the heavy omega or "U" plates.It's a few thou bigger than barrier pex,enough to rub against the flooring underside and damage a wood floor over time.

Unknown

that would depend on the installation method, wouldn't it?

U plates don't allow tubing movement; the omegas, leave enough room so the tubing isn't slammed against the bottom of the wood and you should be fine. we use 3/4" infill for those kinds of installations and it works just fine.

hotsacks

Kitec/Plates

I can't speak for the omega plates (and shouldn't have included them in the original statement), but using the "U's" with Kitec will.I believe, get you into trouble. Try this: press a piece of 1/2" KPAP into a "U" plate until it bottoms,place the plate between your 3/4" sleepers and slide a chunk of flooring over it. Assume the position:keister in the air,head on the ply.You'll see the Kitec pressed against the flooring.Nailed down,I think it must flatten the pipe oval and form a 1/2" friction point.Not good,something that would make a flooring guy wince.With regular pex,there's a hair of air space between the pipe and the floor,kind of a micro tunnel.The fix is to flip the plates - and raise water temps about 10 degs. Or use the Oventrop PAP RE recommends.
Anybody need a 500' roll of KPAP?