Radiant Heat - Pex or Copper

[Junkman]

I am converting the home to propane fired boiler, and will be installing radiant heat under the 1st floor, by placing the radiant between the 12" OC joists. I have gotten 2 quotes, and one said that they run copper from the manifolds to the ceiling, so it looks neat. The other said that they run PEX from the manifolds up. The first contractor said that eventually the PEX will sag, and look very sloppy on the wall. I don't know who to believe, or exactly which way to go. The contractor that originally suggested the copper to the ceiling called to say that he got a few new home contracts on Monday, and that he can't do mine till the spring, so that eliminates him. The contractor that said that they use PEX to the ceiling, said that they can use the copper, but it will add to the costs. He didn't give me an estimate of how much. I did ask what grade of copper they use, and was told "M", and that "L" was much more expensive, and not needed in a hot water system. Your thoughts on that also.
Thanks Junk

 

[FANTM58]

If you have access to the basement and the joists.
I would run PEX Inbetween the joists. But closer than 12" loops.
I would get it sized. Boiler , tubing size /loop runs ETC.
Then insulate between the joists encasing the PEX .
Also be mindful of the material on the wearing surface
Carpet, wood, tile they all offer different issues and need to
Be calculated for .

 

[Jackfre]

The copper recommendation is best, but certainly more costly. If that portion is exposed copper would be best. Both will work, but pec has a much higher expansion co-efficient and will travel. It is difficult to do a pec job and make it look good, but the right mechanic can do it, if he takes his time, lays it out correctly and supports it properly.

 

[theoldwizard1]

PEX will sag on horizontal runs. Just use more support clips.

 

[rlitman]

PEX will sag on horizontal runs. Just use more support clips.

More clips or straps, or whatever it takes to give it sufficient support.

 

[Mr onetwo]

use enough clips and box it in.