[Cob] solar radiant sand bed under cob cottage

[Amanda Peck]

To some extent the more of that sub-surface area you can heat the better.  
Particularly if you have insulated heavily.  Not just the foundation, but 
maybe even out from there.  Even in a small well-insulated shed, Don 
Stephens was able to stabilize temperatures after a couple of YEARS of 
leaving it alone.  Unfortunately the AGS link here isn't right, the one 
comparing it to PAHS is, though.  PAHS is fascinating, the book is still 
available.  There are houses from Virginia to Pac Northwest still using one 
system or the other.  But Stephens' version is simpler.

You run into big troubles if you have groundwater on your site.  Unless you 
only use it for cooling.

http://www.greenershelter.com/index.php?pg=2

Most everybody I've heard from who has radiant floors LOVES them.  The late 
Ken Kern, however, hated them.  I think they work best for neat freaks.

Karl wrote(heavily snipped):

the trouble:
the problem as i understand it is heat also conducts down into the sand bed 
from the alternate source of heat an example is normal radiant heat located 
above the sand bed in the earthen-cob/cement floor.

a solution:
drycreek overcame this by not putting upper radiant tubes above the solar 
radiant sand bed.

the real problem:
i plan to build a small cob cottage & want to heat the whole floor.