Cob: thanks Darel pipes under floor

[Darel Henman]

YanQue
   For some research done see page four of the document pointed to
below.  It discusses the some parameters such as pipe diameter, depth,
etc.   People can skip the mathematical simulation equations and go to
page four for conclusions.  The Koreans have been using the hypocaust
system for about 1500 years.  Currently they are using water instead of
air for the heat transport.  

 http://www.hvac.okstate.edu/pdfs/bs97/papers/P030.PDF

An interesting article by John Siegenthaler, "Questionable Conduct",
about pipe types used is given below.  It has a nice drawing of heat
energy isotherms around the pipes.    Clearly heat layers are not some
ridiculously long figures like 30 feet or so.   Think of heat moving in
waves like the skin on an onion.  

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,76518,00.html

For air I would suspect a larger diameter would be needed since it can't
hold as much energy as at the same temperatures.

> 
> Cat here, Thanks Darel, do you know of any spec's out there, what size
> pipe, how deep a bed for the support and what depth the layers have to
> be? 

If one uses water as the heat transport medium, care must be taken that
any water containing parts containing water not get frozen.  Some people
bleed out the water at night or use some kind of chemical to keep it
from freezing.  I'd want to completely isolate the heated underground
part for the rest during the cold night.

Darel