Posted by Anti-Spam on May 23, 2006, 3:57 pm
I am designing a system which needs to be as maintenance free as
possible. It is for some solar water heaters I want to make for me and
my friends where we live, up in the hills of sunny spain. Some of us
do not have mains electricity and some do not have mains water. I did
start off with some elaborate designs using pumps, PV cells, drain
back systems etc etc. Then decided to scrap all that and design as
simple as possible with the fewest amount of components. I have a link
to drawing which I would like you all to have a look at, and please
feel free to comment on my design.
It is a passive, closed loop system, using Glycol as the heat
trasmission fluid. I decided on trying a header tank to solve the
problem of water expansion, purging the system of air and to top up
the system automatically. The level of fluid in the tank will be level
with the top most pipe of the coil in the tank. I have mounted the
tank slightly higher than the top of the collector panel, in the hope
of stopping reverse flow at night time, or will I need some sort of
low pressure non return valve? I have taken a pipe from the top most
part of the system, elevated another 50cm or so and pointed it into
the top of the header tank. I have done this so if the system should
start to boil, it will vent the steam into the header tank, will this
For the collectors I am uring towards using 22mm Copper pipe for the
top and the bottom of the matrix, connected together with 10mm copper
pipes, running vertically, spaced 10cm apart using "T" junctions
22-10-22 for connecting them all together. Because copper sheet is so
expensive, I am uring towards Aluminium sheet and if its practical
soldering the vertical pipes to the Aluminium, I did not think it
could be done, but this thread on a discussion group said it could,
and I quote "To any one interested you can solder copper to aluminium
by tinning both surfaces useing engine oil as the flux as this stops
oxide building up on the aluminium (seeing is beliving) " on thread
. I will see if it can be done, if not I will clamp the tubes to the
Aluminium with pipe clamps, and use Silicon heat compund. Of course
painting the collector sheet and pipes with matt black paint. I will
use the standard way of mounting the collector in a glazed cabinet
with glassfibre insulation material, heat reflective silver paper and
Posted by Anthony Matonak on May 23, 2006, 7:01 pm
What you want is a batch water heater. You place a water tank
painted black in an insulated, glass faced box and point it at
the sun. It's the least complicated and most reliable solar
water heater you can build. Fancy ones use reflectors, double
pane glass and insulated shutters.
There are plenty of plans for them on the net.
Posted by KDV on May 23, 2006, 8:44 pm
I'm working on solar collectors too. Collectors on the principe as you. You
can see the pictures on my site. I'm working on translating it all in
Englisch but it is not finished yet. See
Kris De Voecht
Posted by Anti-Spam on May 23, 2006, 9:16 pm
Nice work Chris, I especially like the copper fins you have made for
the collector pipes. The overall finish and engineering quality is
very high. Have you tried soldering Aluminium fins to copper pipes,
does it work?
From your workshop it looks like you will be making these on a
commercial basis, do you need any control electronics designed? I
design PIC based systems for control electronics.
mark@markXscotford.com (remove the X to reply)
Posted by KDV on May 24, 2006, 7:49 pm
Never tryed to slodering alu on copper, when I have the time I'll be testing
All what is on my web space are non commercial things only for plesure and
hobby so the solar thing is 70% for déstressing from my day job and making
my days off a little more intresting!
When you started with building your own solar collectors put some pictures
on the net for us to see your progress maybe you give us some idea's ....
I think you better brasing your copper pipes with oxy-acetylene like Mike as
told you, I 'm doing it the same.
For the steame problem: the header tank must be very big I think 1 liter
water is about 750 liter steam ....at atm conditions, correct me if I'm
wrong... What about the pressure of the steam?
Kris De Voecht