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Solar water heating and nuclear energy...

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Re: Solar water heating and nuclear energy...

Postby georgios100 » Wed Jan 08, 2014 9:40 pm

Get Real! wrote:
georgios100 wrote:The problem is the positioning of the hot water tank on the roof of the house.
During cloudy days or at night, the heat loss is just too much!

The hot water tank should be placed inside the home, protected from the elements.

Correct! I made the mistake and I’m wondering how much trouble it’ll be now to move it in the roof.


I would leave it as is... just use the roof tank as a collection tank for cold city water only.
In this case plumb the cold tank to the cold water supply of the house.

Then install a high capacity hot water tank in the house, preferably with an electric resistance heater
to compliment the solar production at long cloudy days. Rework the plumbing to divert the solar hot water
collectors output to the new tank downstairs. Source a small DC water pump to be connected inline to the solar collector
main line. Place a small solar panel to suit the pump and fuse it. You are done!
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Re: Solar water heating and nuclear energy...

Postby supporttheunderdog » Thu Jan 09, 2014 7:43 am

georgios100 wrote:
Get Real! wrote:
georgios100 wrote:The problem is the positioning of the hot water tank on the roof of the house.
During cloudy days or at night, the heat loss is just too much!

The hot water tank should be placed inside the home, protected from the elements.

Correct! I made the mistake and I’m wondering how much trouble it’ll be now to move it in the roof.


I would leave it as is... just use the roof tank as a collection tank for cold city water only.
In this case plumb the cold tank to the cold water supply of the house.

Then install a high capacity hot water tank in the house, preferably with an electric resistance heater
to compliment the solar production at long cloudy days. Rework the plumbing to divert the solar hot water
collectors output to the new tank downstairs. Source a small DC water pump to be connected inline to the solar collector
main line. Place a small solar panel to suit the pump and fuse it. You are done!


Several ideas about tanks etc can be found at the builditsolar website. something suggested there to think about is to have a heat exchanger system by running the hot water from the solar through a large copper coil placed in the storage tank. They even have designs for home built tanks.
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Re: Solar water heating and nuclear energy...

Postby kurupetos » Sun Jan 12, 2014 10:25 pm

georgios100 wrote:
Get Real! wrote:
georgios100 wrote:The problem is the positioning of the hot water tank on the roof of the house.
During cloudy days or at night, the heat loss is just too much!

The hot water tank should be placed inside the home, protected from the elements.

Correct! I made the mistake and I’m wondering how much trouble it’ll be now to move it in the roof.


I would leave it as is... just use the roof tank as a collection tank for cold city water only.
In this case plumb the cold tank to the cold water supply of the house.

Then install a high capacity hot water tank in the house, preferably with an electric resistance heater
to compliment the solar production at long cloudy days. Rework the plumbing to divert the solar hot water
collectors output to the new tank downstairs. Source a small DC water pump to be connected inline to the solar collector
main line. Place a small solar panel to suit the pump and fuse it. You are done!

No electricity is too expensive in Cyprus. A lot more expensive than Canada or the UK. Unless you get your electricity from PV, that's not the wise thing to do.

It's better to have the hot water tank in the basement and connect it to some kind of geothermal system... :wink:

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Re: Solar water heating and nuclear energy...

Postby supporttheunderdog » Fri Feb 07, 2014 8:44 pm

kurupetos wrote:
bill cobbett wrote:
kurupetos wrote:@ BillC
The color of the water storage tanks doesn't really matter, because radiation heat transfer occurs through the flat plate collectors which are facing the sun.

And yes the collector assembly is usually black, whereas the water storage tank only needs to be well insulated to minimise heat losses.

Simples, dear goblin... :)


Yes, ok... but what if there were no black flat plate collector assembly and no insulated copper cylinder.... just the uninsulated plastic water storage tank, would the water in it get hot/hotter and hopefully stay warmish overnight if it was painted black...???

No, because in this case you would have heat losses when there is no sunshine (e.g. evening) and the water would reach ambient temperature within an hour or so.

Also it's a solar water heater, and not a thermal water heater, which is a different thing and cannot reach temperatures high enough for domestic water heating. The metal (e.g. copper) does all the heat transfer effectively because it has a high conductivity, whereas plastic has negligible conductivity. :wink:

Have a look here...http://en.wikipedia.org/wiki/List_of_thermal_conductivities

@GR! Go back to the closet. :mrgreen:


Bill Yes it would get warmer but not a lot and would probably cool down overnight. The solar heating system works ( even with tanks in the roof) because by and large the collectors make enough hot water throughout the day to ensure there is enough for normal usage, which usually requires a few litres a time for washing etc., plus enough capacity to retain enough heat overnight for early morning usage.

It is in fact possible to make simple collectors out of black plastic hose, or plastic pipe painted black and there are some designs for the DIY'er to build themselves, using flattened beer tins to make collecting fins.

I am thinking of adding a second collector at home better angled for the winter sun., I.e. Slightly more upright.

For the systems needing pumps as eg the tank is lower than the collector one needs to assess how fast the warm water naturally flows out of the collector through convection as if the pump is a bit quick one risks filling the tank with lukewarm water.

I am a firm believer in trying to use solar power as much as is possible, preferably in small scale schemes , to reduce reliance on centrally supplied power. Solar thermal in the home is probably under used: build a big enough collector and put in a big enough tank and one can even run a small heating system. After that solar PV, bearing in mind it is expensive to make and fit the panels. Bearing in mind how hot PV panels get! and as they warm up they lose efficiency, so one should look at hybrid systems to use water coolers to extract the waste heat . Kill two birds with one stone. Electricity and free hot water out of one panel.
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Re: Solar water heating and nuclear energy...

Postby bill cobbett » Sat Feb 08, 2014 3:05 am

Thx STUD... am gonna experiment with one or two things this Summer... if it stops raining in London... (squelch)
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Re: Solar water heating and nuclear energy...

Postby supporttheunderdog » Sun Feb 09, 2014 6:37 am

bill cobbett wrote:Thx STUD... am gonna experiment with one or two things this Summer... if it stops raining in London... (squelch)



Try looking at http://www.builditsolar.com/index.htm.

There are some nice designs for solar air heaters. Just have to persuade the wife I have to drink large amounts of beer too make the collector. Then make holes in the walls....


I have been thinking of one of them plus adding a copper pipe water collector on the top, using the air collector as the fins for the water collector. If that was to work I would think about using it to drive a heating system, just need a large enough tank to hold enough warm water to last through cloudy spells.

One might need to find ways to dump heat in summer.

I am also tempted by the use of a heat pump using either a ground/air or a ground / water heat exchanger, mostly to provide air cooling for the summer. but not sure how practical it us to retrofit . Too much limestone bedrock not too far down.
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Re: Solar water heating and nuclear energy...

Postby supporttheunderdog » Sun Sep 07, 2014 5:05 pm

new report here of a solar water heating system to beat all solar water heating systems... to make electricity using solar generated solar heated steam via a graphite based heat store.

http://cyprus-mail.com/2014/09/07/new-s ... ectricity/

they reckon it can produce at 40% of the cost that EAC sells at.

Hope it works.
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Re: Solar water heating and nuclear energy...

Postby repulsewarrior » Sun Sep 07, 2014 6:55 pm

supporttheunderdog wrote:new report here of a solar water heating system to beat all solar water heating systems... to make electricity using solar generated solar heated steam via a graphite based heat store.

http://cyprus-mail.com/2014/09/07/new-s ... ectricity/

they reckon it can produce at 40% of the cost that EAC sells at.

Hope it works.


...interesting.
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Re: Solar water heating and nuclear energy...

Postby kurupetos » Mon Sep 08, 2014 3:40 pm

supporttheunderdog wrote:new report here of a solar water heating system to beat all solar water heating systems... to make electricity using solar generated solar heated steam via a graphite based heat store.

http://cyprus-mail.com/2014/09/07/new-s ... ectricity/

they reckon it can produce at 40% of the cost that EAC sells at.

Hope it works.

Are you kidding me? This technology is more than 20 years old. :lol:
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Re: Solar water heating and nuclear energy...

Postby supporttheunderdog » Fri Nov 14, 2014 2:45 pm

kurupetos wrote:
supporttheunderdog wrote:new report here of a solar water heating system to beat all solar water heating systems... to make electricity using solar generated solar heated steam via a graphite based heat store.

http://cyprus-mail.com/2014/09/07/new-s ... ectricity/

they reckon it can produce at 40% of the cost that EAC sells at.

Hope it works.

Are you kidding me? This technology is more than 20 years old. :lol:


So why is not widely used?

Can it be economically built small enough to sit on a roof and run a whole house?
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