On Sun, 22 Jun 2008 14:22:56 +0100, David Hansen
wrote:

On Sat, 21 Jun 2008 17:47:37 +0100 someone who may be MM
wrote this:-

Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft?

You can. Whether this is advisable is another matter. One question
is what happens if the collector manages to make the water very hot,
perhaps creates steam. Even a small collector can do this if it is
only heating a small volume of water. Control of excessive
temperatures is an integral part of good solar design.

There are some thermal stores made out of plastic. A (very
expensive) range is at
http://www.consolar.co.uk/index.php?option=com_content&task=view&id=6&Itemid =15.
The difference is that the plastic vessel is designed for this use.

Just had a look - I'll bet they are expensive!! (No prices stated is a
dead giveaway.) With all new technologies one has to find the
"Ryanair" version, as too many suppliers will be jumping on the
bandwagon and ripping people off, especially those with no DIY skills
who have to trust tradespeople entirely. I tend not to, in principle,
although, rarely, I am pleasantly surprised, like receiving a
Christmas present one actually wants. 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. My watchword is: IKEA!


The other important factor in solar heating is insulation of the
cylinder/store to maintain temperature. As a minimum double
thickness sprayed on foam is desirable, triple insulation is better.
If I was making a small system for a few basins then I would
consider having a special cylinder made by McDonald Engineers
http://www.mcdonald-engineers.com/products/cylinders.htm or one of
their competitors.

For a home made collector plenty of designs are available and I
would study several before deciding on a design.

Yes, I have studied numerous designs and watched some YouTube vids.
Now is the time for hands-on experimentation, which is where I'm at.

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. Maybe I'm lucky in my back garden being a real sun trap.
It does get incredibly hot during the summer (not today because it's
so windy right now).

MM