Replies

1. 
   NRTRob | May 29, 2006 09:49pm | #1

   If you can tie it to the mesh, great, as long as you are making sure the tubing won't get punctured or cut later (i.e. making sure control cuts are of limited depth, not running under wall plates that will be nailed down, etc).

   However, the difference between center mounted and bottom mounted tubing is small. So if you have to go under, you're not crippling your system or anything like that.

   -------------------------------------
   -=Northeast Radiant Technology=-
   Radiant Design, Consultation, Parts Supply
   http://www.NRTradiant.com
1. 
   Rosey | May 30, 2006 03:28am | #4

   Thanks for replies.

   It sounds like having the pex 1.5" under

   surface or 3" under surface aren't determining

   factors.  Would there be an advantage one

   way or the other as far as the concrete heat

   dam and radiation at surface at either depth?

    

1. 
   donpapenburg | May 30, 2006 05:49am | #5

   I was told to put the mesh over the pex , reason was that the mesh would act as a thermal bridge between the tubes and make for a more even heat .  I put down a couple strips of mesh then laid and  tied my tube to that .  Then I put in the reinforcing mesh and rebar as needed and then tied off any pex that needed help running straight.    I may be wrong but it sounded right .

1. 
   CloudHidden | May 30, 2006 06:19am | #6

   Above or below won't make any practical difference in the thermal characteristics of the slab.

2. 
   Snowmon | May 30, 2006 05:52pm | #8

   "I was told to put the mesh over the pex , reason was that the mesh would act as a thermal bridge between the tubes and make for a more even heat ."

   This conductive benefit would be very slight, and more related to conductive contact with the mesh than being above vs. below the mesh. 

   Having the tubing closer to the surface would improve the response time slightly, and the installation would be easier on top. 

2. 
   NRTRob | May 30, 2006 04:16pm | #7

   Having it higher slightly reduces response time and water temperatures. But, it is very slight. As in, not generally even considered in any of my calculations slight!-------------------------------------
   -=Northeast Radiant Technology=-
   Radiant Design, Consultation, Parts Supply
   http://www.NRTradiant.com

2. 
   Danusan11 | May 29, 2006 10:31pm | #2

   I've always seen it tied above, would think it would be easier to keep uniform pattern in layout

3. 
   CloudHidden | May 30, 2006 03:22am | #3

   Easier to tie to the mesh if the mesh is already in place. I once snaked it through two layers of rebar to tie underneath and that was a nightmare. Use the proper ties. You don't want anything that will pinch it. Best to use a concrete crew that knows how to work around it. And pressurize it with air when pouring the concrete. If it gets punctured, you can locate the spot an patch it. If you've filled with water, you'll have a mess. If you don't have it pressurized with anything, you won't know if you've created a leak.

4. 
   Tim | May 30, 2006 10:50pm | #9

   The practicality of putting tubing under the mesh makes this an unrealistic manner of installation. Tying tubes down to mesh as its being "rolled" out on top of it is the easiest way toaccomplish this type of imbedded installation.

1. 
   ronbudgell | May 31, 2006 01:28am | #10

   Not quite. The easiest way is to unroll the tube and staple it to the foam insulation with a stand-up stapler made for the job. I don't know what they are called but they push a plastic barbed staple into the foam to hold the tube in place. Much faster and easier than wiring to the mesh or tie-wrapping or any other way of fastening. Then you can toss your mesh down on top of that. Or forget the mesh and pour a fiber mix.

   Ron

1. 
   donpapenburg | May 31, 2006 05:35am | #11

   You got that right !  tying tubes is a pain.

2. 
   johnnyd | May 31, 2006 03:24pm | #12

   Pretty standard in these parts (SE MN) to do exactly that....staple the tube to the foam, then re-bar or re-mesh, then pour. Sensitive HOs who see this shudder when the concrete crew rolls wheelbarrows over this.  In the case of my slab, they used pieces of plywood to offer some protection on the longer wheelbarrow runs.

   Advantages are:

   Automatically keeps the re-mesh/re-bar up off the bottom

   Keeps the tube from floating up and interfering with the power trowel

   Insures that the tube stays down enough so you can cut control joints without worry.

   Of course it goes without saying that you should have some air pressure in that tube...have the HO keep an eye on the gauge.

   As far as placement of the tube within the slab....it doesn't make any difference once the slab is up to temp, provided there is adequete insulation underneath...like 2" of XPS.

   
3. 
   Tim | May 31, 2006 04:23pm | #13

   Ron,

   Read post #1. There is no foam. Given the installation as described, attaching tube to a substrate or insulation is not an option. There are many effective ways to install pex in a floor, but over a steel subfloor, those choices are limited.

1. 
   ronbudgell | May 31, 2006 11:57pm | #14

   Tim,

   You're right. I didn't read the original carefully enough.

   Ron