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solar water heater effeciency - Page 2

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Posted by N. Thornton on September 1, 2004, 9:25 pm

Needs to be way bigger - not just twice the size. Nick W made one that
worked well, see the newsgroup. Plastic hose coiled, polythene sheet
cover is all thats needed. The temp rise is so low its pointless using
anything better.

A big foil reflector may be a cheaper way to add more heat than more
piping. Spacing the pipes out by about half to one pipe dia helps a
bit as well, each pipe gets more sun when the sun angle is lower.


Posted by Adrian Brentnall on September 1, 2004, 5:22 pm
HI Neil

Had you considered using an old central heating radiator as a
collector. Not ideal for domestic hot water heaters (fairly slow to
heat up) - but pretty easy to try out.....

I made one of these many years ago - seem to remember that I had two
old rads - total of about 3m-squared - in a home-made 'cold frame' -
and it produced startlingly hot water!

I'm not sure about using plastic tube - don't know how good it is at
insulation -

Another way (very low-tech) is black-painted  iron / steel
roof-sheeting in a cold-frame - with water running down the 'valleys',
Collect it in standard plastic gutter at the bottom end - and
distribute it in some way (Cu pipe with holes in it ?) at the top end.
Fit your temperature sensor to the sheeting. Crude but effective <g>

Have fun
Suffolk UK

Posted by nicksanspam on September 1, 2004, 6:04 pm

I started alt.solar.thermal for "PRACTICAL uses of the sun's heat."
Maybe we need another group for impractical uses, eg systems with
very low efficiency :-)


Posted by Neil Adamson on September 1, 2004, 8:12 pm
 Thanks Adrian
Ive got an old radiator & was my 1st thought - but then I started to worry
about the effect the rust on the pond - plants, fish etc. & it will rust
because you're pumping air enriched water through it.
Nick - surely any hombrew use of the suns energy is a PRACTICAL use -
especially if the alternative is to use electricity or burn fossil fuels to
get the heat.

Posted by News on September 4, 2004, 11:25 am

But super cheap systems. Flat steel panel radiators work quite well, and
they are very cheap. As they are ferrous you need a heat exchanger.

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