My (large) solar thermal project

Solar thermal energy in all its forms: solar heating, hot water, choosing a solar collector, solar concentration, ovens and solar cookers, solar energy storage by heat buffer, solar pool, air conditioning and solar cold ..
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Philippe Schutt
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by Philippe Schutt » 26/12/13, 20:36

if the return to the panels is too hot, it means that the balloons are hot enough for the day.
And with 25m2, no need to finish with the pump flow, in any case in summer.
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dede2002
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by dede2002 » 05/01/14, 15:06

Re :D ,

Indeed I consulted the balloons doc, the power of the exchangers goes from 33 to 43 kW (each), there is room.

I am resting my modified diagram, I have included the heating circuit, as well as the spreadsheet set to 25 m2 and 15 ° delta t.
with 300 to 800 W / m2.

If someone knows formulas to calculate the pressure drops, for 70 ml of tube dn 20 to 1 m / s I am taker!

Image

Image

A+
Last edited by dede2002 the 05 / 01 / 14, 15: 29, 1 edited once.
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PITMIX
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by PITMIX » 05/01/14, 15:24

Hi dede2002
On my solar water heating system I am faced in summer with problems of overheating of the DHW tank because the power supplied is greater than the demand.
In the morning the circulator starts with a balloon at more than 65 ° C and the DHW quickly reaches 80 ° C.
The means that I put in place is the partial concealment of the solar collectors. So I balance the power against the demand.
Have you thought of a solution for the risk of a problem on your very impressive power circuit?
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dede2002
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by dede2002 » 05/01/14, 15:37

Hi Pitmix,

My idea is to first heat the DHW to 60 °, then the buffer to 80 °, then stop the pump and let the panels empty overnight (fill with air).
In summer the pump should stop after a few hours of sunshine.
Then I will resume the heat of the buffer for the ECS, overnight.
Or for daytime heating, between seasons.

A+ :D
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dede2002
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by dede2002 » 05/01/14, 16:02

In fact I favored the buffer for storage for several reasons:
1- heating the DHW to more than 60 ° (50 °) precipitates the tartar in the tank.
2- with the tampon, I don't lose water during the expansion.
3- above 60 ° risk of burns, avoids a mixing valve.
4- possibility of additional solar heating
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Philippe Schutt
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by Philippe Schutt » 05/01/14, 17:28

http://www.tlv.com/global/FR/calculator ... iping.html
they give the formula and calculate the pressure drop

800L is a lot of DHW and the 300L will cool without the solar can heat it.
Why not put them in //?
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dede2002
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by dede2002 » 05/01/14, 20:05

Thank you for the link!

it gives me about 0.8 bar pressure drop at 1 m / s.

The 800 liters of DHW is for about fifteen people.
In the quotes I received I was offered with 1500 l. DHW, i.e. 1000 l. DHW + 1700 l of buffer, with 15 m2 of panels.

I will study the assembly in //, but the solar will not heat more the 300 l.?
It can be heated by the buffer, but 300 l. with me it goes quickly, and the losses are around 2 ° / 12h.

If it is filled with hot water, shouldn't it have time to cool down?

A + and thank you for your opinions

:D
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Philippe Schutt
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by Philippe Schutt » 05/01/14, 22:15

be careful, you don't have 70m in a line, or well? As soon as it divides, the resistance is divided too. So you should have less ...

// the 300L would be unused, but it's true that with 15 people it's risky.
But then what is the use of having a balloon with 2 coils?

is there a hot water loop? if so, it could be done with the 500L, so as not to cool the 300L.
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dede2002
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by dede2002 » 05/01/14, 22:30

Yes actually on the roof the pipes separate, it will also be necessary to count the pressure drop of the solar panels.

Regarding the balloons, the 300 l. I already have it, not yet unpacked ...

And for the 500 l. the price difference is minimal between 1 or 2 exchangers, it allows to heat the water which will enter the 300 l. the morning.
I could also heat the 300 l. from the buffer, choice depending on the temperatures of the balloons.
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Philippe Schutt
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by Philippe Schutt » 05/01/14, 22:44

Heating water with gas before it enters the 300L or heating it with gas directly in the 300L, what difference?
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