[Cob] RE: Solar radiant floor

[Peter Ellis]

   >
   >Climbing out of lurk,
   >
   >Karl wrote:
   >my current plan is as follows:
   >i'd like to incorporate solar hydronic heat into my earthen floor.
   the
   >method that has intrigued me the most is to incorporate a large sand
   >bed under my earthen floor and run pex trough it heated by solar
   >collectors....
   >Karl on the strawbale listserve and in the recent edition of the Last
   Straw
   >they addressed the issue of the bubble wrap based on research in
   Canada. The
   >stuff did not perform well at all below grade. That said, I agree
   with your
   >thinking regarding the deep heat solar radiant concept. I am doing
   exactly
   >that on my home under construction.
   >It has 2-3' of sand and sand/gravel mix with the tubes at the bottom.
   There
   >is plastic and somewhere between R20-30 of rigid foam. So it is an
   insulated
   >box so to speak. The more sand you can afford probably the better,
   some have
   >put in as much as 6' !!! Then in Aug start pumping the heat in. If
   you have
   >a super insulated structure and a fairly decent sunny climate this
   should
   >cover most or all of your heat if the house is detailed well. In a
   small
   >cabin you could probably get by with 6 collectors.
   >Chuck in Wisconsin
   >
   >---
   I guess I'm missing something - why sand ? Why not just dig down as
   far as necessary, lay in the "plimbing" and put back the earth you dug
   out in the first place ?
   I don't see why one would go to the effort and expense of removing
   that earth and replacing it with something else.  From my seat it
   sounds like an unnecessary complication, so if there is some
   convincing argument for the sand approach, I would be interested in
   hearing it...

   Peter