On Fri, 25 May 2012 11:28:35 -0700 (PDT), harry wrote:

Most of the heat in the ground comes from rain percolating into it.

That could be a transport mechanisium rather than conduction which is
the only other heat transfer method available in the ground.

The rain is also why heat can't be stored there. The water "washes it
away."

Moving ground water is certainly "a good thing" for a ground source
collector, the water constantly brings heat in from the surrouding
area. Dry sandy soils are not good, wet loamy ones are.

--
Cheers
Dave.