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re: hair brained solar cistern???
7 dec 2002
aj wrote:
>hello,
hello aj,
>...as the sand was compacted, i added quite a bit of water...
perhaps you can keep it moist. the main mechanism for upward
heatflow in soil is evaporation below and condensation above.
>i have just started documenting statistics on the house, but interestingly,
>it appears that the sand bed floor temperature peaks during the over-night
>hours. if this works out to be true, it would appear that the thermal
>flywheel is about 12 hours out of phase with the sun, which is desireable.
you might see this with that simple simulation. some architects get
excited about trombe wall delays and forget how inefficient they are.
>there are at least 15 homes in the wisconsin area that use similar
>systems: solar collectors, sand beds, radiant floor heating.
there's a guy in the adirondacks who's done them too, but, oddly enough,
all of his houses have woodstoves. i do respect real-world experience,
moreso when it doesn't seem to contradict 300 year old theories :-)
check out my article in the jan/feb 2003 issue of solar today.
>the folks at gimme shelter construction and artha renewables have had great
>success with these homes.
shark repellent works very well in pennsylvania :-)
>i spoke to a few of the owners of these homes before considering a sand bed...
they are probably biased.
>...i hope i don't come of sounding like a sand-bed bigot, because that is
>not the case. the fact is water holds a lot more btu's than sand, but
>i wanted to avoid a system that requires controls and maintenance.
i don't see much of a difference in the controls or maintenance or
a great disadvantage in specific heat by volume, but these sand beds
appear to introduce a tremendous thermal resistance between the heat
source and the house, which requires a very high temperature source
to supply a reasonable amount of heat power to the house.
nick
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