Ian Stirling wrote:
wrote:
Ian Stirling wrote:
wrote:
Or the OP could buy ?90 worth of hosepipe, polythene & pump, and get
10kW with 1/10th the run cost of the 3kW heater.
Not a tough choice. Cheap pool solar heating is very easy to make btw,
probably easier than installing electric into the water.
Details?
10m^2 collector area, how does it work?
Polythene over hosepipe?
ok... firstly I would not use an open roof surface for collection, as
a) it will also collect bird**** and other assorted bacteria
b) it will leak water onto the roof structure underneath the covering
and rot it.
Buy a ?50 pump, checking it can run continuously and has a type of
motor that can be slowed down eaily.
Spend the rest of the money on hosepipe, the more the better. Avoid
orange, white or light grey. Wind it in a huge flat spiral pancake.
You'll get a lot more heat if you space each turn out by one pipe
width, but that requires wire or similar to hold it togther/apart. Aim
for 10 square metres or more.
Cover the pipe with polythene, add the pump on an RCD, and run it at
lowest speed setting.
You now have a fairly efficient low cost 10kW heater.
Hmm.
10m^2/4cm = 250m.
Best price for 30m I can find seems to be about 12 quid.
Call it a hundred quids worth of hose.
Without the space, it's more like 250 quid.
I've wondered in the past about twinwall sheet.
If only there was a nice leak-proof way to seal hose to the ends, it'd be
ideal.
One sheet of clear twinwall on top of one sheet of black.
The design I gave last night is not in fact the design I would use.
There are many improvements that would, erm, improve it, including cut
cost. I was just too tired to go over em all then.
1. The main one that cuts cost is to use reflective plastic to reflect
more sun onto the collector, enabling a smaller collector to be used.
This can halve the amount of hose needed.
2. connect several pipe runs in parallel, now much less pumping power
is needed.
3. As well as using a hose collector, dont forget the cheaper option of
a reflective mylar sheet on a frame to shine sun direct into the pool.
4. Its quite possible to space the pipes out further, this improves
cost per kW at the expense of more space. More spaced out pipe panels
are more efficient financially, and less efficient thermally.
NT