Cob heat storage

[Gale]

uwe wrote:
> 
> Hi Folks,
> 
> this is a bit off topic, so I hope it won't develop a long thread. For quite some time now I've been trying to find appropiate (what's that?) phase change materials to store heat gained by a solar collector. Parrafins are great, but expensive and flamable (ever lit a candle?). Inorganic salts are corrosive, other materials are toxic, expensive, ... Where is the one I want? It should be in the 100-170 F range, cheap, easy to obtain, and safe (though I know that nothing is perfect). Anybody knows
> 
> Uwe

If someone finds a good phase change material that would be very
interesting.

In the mean time, water is the best heat capacity material.  Can it be
combined with cob?
It might work to fill used (plastic?) (glass?) bottles about 7/8 full
and embed them in the
wall.  I have tested small plastic bottles with tight tops in repeated
freeze thaw
cylcles and the bottle didn't fail.  But that wasn't many cycles.  If
the bottles 
are embedded vertically, the top would not need to be as tight.  Used
half gallon
platic milk bottles might do.  The question for experiment is whether
the space at the
top of the bottle would get the expansion on freezing or whether the
bottle would
expand sideways leading to unacceptable heave built into your wall.  If
the space at the top
and the shape of a glass bottle mean it does not break on freezing, then
there would
be no question of heave.  A few cycles should answer this one for a
particular bottle shape.

Water is certainly cheap, easy to obtain, and non-toxic.  Then there's
the bottle....  :)

Gale - disabled theorist lurking on the list