On Sun, 22 Jun 2008 18:09:56 +0100, David Hansen
wrote:

On Sun, 22 Jun 2008 15:12:43 +0100 someone who may be MM
wrote this:-

http://www.consolar.co.uk/index.php?option=com_content&task=view&id=6&Itemid =15.

Just had a look - I'll bet they are expensive!!

Four figures I believe. However, they do claim to reduce a number of
disadvantages of normal thermal stores. Whether the price is worth
the result is a matter of personal prejudice.

I reckon solar heating is still seen, in Britain at least, as quirky,
expensive, "designer" -- and there will be much exploitation going
on, no doubt. As ever, no guidance from the Brown mob. Germany is far
and away ahead, AGAIN!

I always start from the basis
that a company is trying to sell me something that I could get
elsewhere in a similar design for much less.

http://www.navitron.org.uk/page.php?19

"Navitron Ltd is committed to providing low cost alternative energy
solutions to the consumer and small business. For far too long,
some companies have made huge profits from solar energy scams,
ridiculously over-priced double-glazing units and funny magnets you
stick in your hot water tank to ward off evil spirits! Don't get us
wrong: We're a profit-making organisation; just not a profiteering
one."

Hey! They can be my friend!

Re your comment about steam, this system will be open, therefore there
won't be any pressure build up. Also, the whole device is mounted
outside the house, with the collector on a slant against the
south-facing wall and the tank mounted above it, probably on 4" x 4"
fence posts.

In essence you are building an "african" water heater, of which an
example is http://www.navitron.org.uk/page.php?55. The steam vent
on the right hand side of the cylinder is necessary and steam comes
out of it even in the UK.

One of the disadvantages of a thermo-syphon design is that if the
collector overheats more water will flow to the collector, to be
turned into steam. The steam then bubbles up to the vent and more
water flows to the collector. One of the advantages of pumped
designs is that if the collector overheats the limited amount of
water in the collector is turned into steam. This forms a steam
bubble which goes a little way along the pipes and then stops. When
the sun goes down water flows into the collector again and, provided
the collector is robust enough, operation then continues as normal.

If you do this put the vent through the roof so that you don't
introduce dampness into the loft.

The tank is going to be mounted outside on the wall next to my small
annexe, where I have sink facilities. Nothing is going to be installed
in the house. I even take the cold water from the garden tap.

MM