On Sun, 22 Jun 2008 11:26:40 +0100 (BST), "Dave Liquorice"
wrote:

On Sun, 22 Jun 2008 10:45:43 +0100, MM wrote:

the temperature of the water had increased to *beyond* hand-hot. That
is, I could just about dip my fingers in, but not for more than a
second. The bucket did not deform at all.

So probably not much above 60C or 70C a decent solar collector is
perfectly capable of boil it's circulating water. Plastics do not soften
in a linear manner.

I don't need it to boil. Just to get hot. I've just popped out the
back and run the tap after 2 hours in the (today, not very hot) sun
(no collector tank yet!) and the water is already warm, despite
today's strong winds. This is even before I construct the insulated
box and paint the pipes black.

http://news.bbc.co.uk/1/hi/england/cornwall/3035606.stm
http://news.bbc.co.uk/1/hi/england/somerset/7175037.stm

Cold water storage tanks are not designed to hold hot water.

So this must exclude plastic (i.e. non-metal) as a material, yes? I've
now stuck an advert in Freecycle for an old loft galvanised tank. (My
old one in Bucks would have been ideal.)

MM