"Steve Shantz" wrote in message
ups.com...

Near the end of 2002, there was a long
thread at alt.solar.thermal on
the solar cistern that Alan Stankavitz installed
in his home. (www.daycreek.com)
Alan's design is not at all like what you have
dug up, but it is a related idea that has some
merrit. The storage potential in Alan's
system is much more short term, and the design
is very different.
Performance expectantions are very different
too, subsequently, his cost is much less. I wonder
what Alan does with the heat from all of
those panels in the summer? Did he install a dump load?

A lot of the discussion in that thread was
related to trying arrive at an understanding
on how heat flows through Alan's system, (and trying
to convert Mr. Pine). This is a very important point
to consider.

hit the key too early in the previous post - way too early

If I recall, the thread centred on the performance of the floor, which was
good. He was using sand to store heat, which is not the best of materials
for holding heat. The conclusion was that the sand was wet, and when dried
out the performance would drop off.

I suggested this from ground up:

- insulation
- concrete with plastic pipes embedded.
- insulation
- cement screed with underfloor heating pipes embedded.
- floor covering.

Essentially a lower concrete layer in which to store heat. The upper cement
layer is the normal underfloor heating thermal heater floor.

You need a floor anyhow, adding more concrete, pex pipes and insulation is
no great expense. The control system would need to be set in such a way
that solar heated water is sent directly to the cement screed and DHW. When
there is available heat and not required for heating purposes, it can be
stored in the bottom concrete floor section, and extracted at will. The
incoming cold water mains pipe could also loop around the concrete floor and
preheat the DHW.

OK that is for a slab on grade. With a basement you store under the
basement in a well insulated tray of concrete in an insulated tray, with
insulation over.

Water holds more heat, that is for certain, but as soon as you put it into a
container it wants to get out and usually does in time. Using dense
concrete under the house, and enough of it, a fare amount of heat can be
stored, even at low temperature.

Or have an insulated semi sub-basement (crawlspace) with a large water
thermal store made up of small off-the-shelf water cylinders. If one
springs a leak, isolate it and replace quite cheaply.