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Solar geyser


Clint
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Wetkit this was late in the afternoon when I took the photo.

I get about 10 hours of sun on the tubes this time of the year but the geyser only gets to 62 degree Celsius.

The evacuated tubes face north. 

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Hi Clint,

To me, that does sound a bit low, especially with evacuated tubes, which is supposed to be much more efficient than flat panels.

Do you perhaps have a controller or timer on the pump that stops it so that the water ds not get too hot?

Either that, or the pump flow is too high or too low.

But, if if it works for you, who am I to judge :)

 

I really like the idea that the pump is powerd from a solar panel. Takes away the need for a controller or timer on the pump.

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Very Cool Guys!

I know a lot of the chaps use Thermosiphon

http://en.wikipedia.org/wiki/Thermosiphon

Putting the solar collector source lower than the water container.

The Natural convection of heat takes over, its extremely impressive what flow you can get off it with no DC pump.

I know a chap who has installed it like this. I will try and get hold of him so he can show us :)

Regards

E

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Hi Clint,

To me, that does sound a bit low, especially with evacuated tubes, which is supposed to be much more efficient than flat panels.

Do you perhaps have a controller or timer on the pump that stops it so that the water ds not get too hot?

Either that, or the pump flow is too high or too low.

But, if if it works for you, who am I to judge :)

 

I really like the idea that the pump is powerd from a solar panel. Takes away the need for a controller or timer on the pump.

I'm sure something is not working properly .I might of overheated the ITS  10 w DC pump. When I first installed the solar the thermostat was set way to high. I recently installed a geyser wise controller 

Thanks for the info 

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  • 7 months later...

Hi Clint

 

Please allow me to tell what I did with the solar geyser issue: I took a long and hard look at the whole matter:  different types, pumps, controllers etc etc. (And do remember Murphy's Law: the more gadgets there are the more likely something will break down...) Finally I decided that half-measures are not good enough. If you want to go green, go all the way. I did not want to use one kw of electricity any more. So I installed two low pressure solar geysers (without elements) IN SERIES, meaning that the one feeding the house (at almost 75 deg) is fed from preheated water in the second one. It works like the proverbial charm, we need a small amount of very hot water so it lasts longer. I close the cold water supply for up to three days during very cloudy weather so the hot water in both geysers is never cooled by inflowing cold water. 

Have fun. Windwize

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Guys thanks a lot for that info,I have sold the house but the geyser still got to +- 60 degrees on most summer days but 70 degrees plus would be perfect

The idea of 2 geysers in series is a great idea which I never thought of.

I would definitely use 2 evacuated sets in my next installation and maybe 2 geysers.

Excellent idea 

Thanks

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Well, I did the same, but just with 2 High Pressure geysers, one vacuum tube and one flate plate.

The flatplate is basically the pre-heater. Currently running around 80 degrees at the tap :)

Might have to look at installing auto temp regulators at each tap :(

 

Depending on your usage, I would rather like to see how a 200L vacuum tube system would do with a 300L to 400L geyser. 200L is just a bit small :(

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  • 1 year later...

I have two solar geysers on my roof. One is a direct high pressure unit, where the tubes (20) goes into the geyser. This as far as I can tell is a much more efficient unit. I also have an indirect system that feeds the direct one, effectively pre-heating the water. This one has a geyserwise controller on with 32 tubes (a rack of 20 and a rack of 12 in series). This geyser does heat up the water fairly quickly, but the water does not stay heated. It has quite a bit of heat loss, even though we have two non return valves and two heat traps in the system to prevent water circulation.

 

The direct system's only problem is if it gets really cold, the pipes to and from the geyser ice up, effectively closing off the water  :D

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