24 June, 2015

DIY Homemade pool water solar preheating system - by Jordi

Economic system of heating pool water
This past summer Jordi from Valencia was consulting on how to heat the pool water with economic polyethylene tube, and discussing their results, and is happy to share it with you.

Surely he noticed this post (system that does not use nearly as efficient) and was encouraged to heat his pool that way, and wanted to "removing the cold", raising its temperature from 18 to 25, a more comfortable temperature, taking advantage of the close roof surface where the sun hits well.

Jordi told me that he would use PE pipe Ø20 mm. and had doubts if it would work; the pool is quite large , 14x3 meters. I had thought to extend about 250 meters tube had calculated that fit on the roof.

Going on

Said and done, using a pump 2000W peak and a control box with its thermostat, programmer, etc, launched his idea with water at 3 bar pressure. Jordi, in response to the sensor as described in the blog,  spread on the roof several "coils" of PE pipe connected together and raised up the pool water directly through a pump controlled by a thermostat . The water in summer is 18 ° (too cold for swimming, is a temperate zone) and was intended to raise it to the roof and when the temperature inside the tube reached 30 degrees, the thermostat ripped pump to circulate the water, and at least down to 25 ° C. So, until the temperature of the pipe down, to leave the Sun, the thermostat triggers and stop circulation.

Jordi already had the facility to heat the pool water through a heat exchanger connected to the gas boiler. What he has done is a new bypass that circulates water through the "donuts" that has put on the roof. It has protected with insulating largely hose PE to have no loss (you lose a 3rd / 4th from the roof to the injection of the pool). It has a thermostat in the engine room with a probe in the last "donut " , so that when the probe detects 25 °, for the pump (which later changed to 30).

Indeed systems using the same principle used to raise the temperature of pools when it's sunny, function and increases of several degrees water temperature, and it shows, for example that it seems worthy well and raises the temperature of your pool small to 32ºC (click). It will not be as efficient as the system with black "canvas" with indoor coil water; to be consulted cost before deciding, because with them the cost of moving water is much smaller, being designed to facilitate the capture of heat and water circulation. We have to find a compromise between efficiency (low thermal losses ) and energy savings (pump), and 30 seem on track, temperature and much more heat is lost to the air transfer pipes during stops. Another good idea is to put up a transparent insulator, but as thin plastic is resistant to UV as polycarbonate or similar plastic greenhouse does not last more than six years (must assess its cost / efficiency gains); Jordi finally put a thin film (as seen in some images) that increases performance and will endure a couple of years (I guess). On the other we must bear in mind that 250 mts X Ø20 are many liters of water to move through the pump , especially in starts and stops; will cost set in motion much water, the fewer starts / stops do better. Although putting a single powerful bomb is a good idea, it is best to put a pump to circulate the water slowly (much speed is not necessary), and, if possible, work with two solar panels 100W peak to come out totally free, so if it's sunny, it starts, and if not, it stops. With 200W peak, connected directly with a simple inverter 12V 220V, give sufficient also between 10 and 16 to power a 75W pump without anything else.
Although the waterfall is quite large, if there is air in the circuit, and being a closed circuit to the pump height would not affect him (by the theory of communicating vessels):

Jordi has taken much of the roof:

He says it has built a panel from which controls when moving or stop the pumps . Using a thermostat, is marked at what temperature are connected or not. The probe of this thermostat is at the end of the circuit, protected with reflective paper to capture only the temperature of the tube and not the outside. Being the protected probe when it detects the cutting temperature, in this case 29º, it is likely that the entire system is more than 30 °. The funny thing is that this flow, the water rises to 22 ° and 30 ° so low continuous , so Jordi understands that when the water temperature rises above are in midsummer, the system will yield much. The panel has built with pieces that have been recycled. See that the injection temperature is shown in the picture is above the temperature of the circuit. This is not true, what happens is that the thermometer probe inlet water pool jumps of 1 in 1 degrees, while the circuit jumps from 0.1 to 0.1. Still, I believe that the loss in º of the descent (as it has all lined pipe insulation) 2nd round.

In summer performs very well. It has risen cutting temperature at 30 °C, so that the system is operated when the temperature of the probe, shaded and secluded reaches 30 degrees.Once the water is the water that goes down to the pool reaches 60 (yes, 60) begins to circulate, during the first minutes, as the whole circuit takes a while the sun. After a while, the pool water "cooled" donuts, and the temperature was stabilized at 38 ~ 42 °. When the probe receives water at 30 °, to the system.
The system has reached nine hours followed function. This, 15 liters per minute, the pool involves injecting about 8,000 liters of hot water.

It has put a regulator on the pump to regulate the flow , because the pump is large and when it starts pulling lot and afraid that burst everything. The installation is made ​​of tube Ø50 and the circuit of the "donuts" is Ø20. The pump works, and much, tells me.
Surely the end replace the large pump for a couple or three floors, sandwiched between donuts.Thus save a lot of electricity.

Has spent the round tubes where could:

Here the coils are appreciated, flanged tubes tied electrician together:


The bad part - tells us - is that the pool is very large (80,000 liters) and energy intensive system (two pumps, one in 1100 and another 700 watts) . Like getting up in August at 25, has risen 35 cutting to prevent pumps work -consuman- Therefore leaving the heat build up a little before activating again.
At first, I made ​​the cut at 25, and the system worked almost from early morning until nearly nine p.m.. Too many hours of operation for as little differential degrees. Now, with the cut almost 30, will yield better. It indicates that in a second phase will be shown when the system is practical and does the job. This second phase is to replace the two pumps by 3 smaller of which is used to move the water floor heating, making it ideal as it is not necessary flow, but keep moving "minimal" so that the water coils are hot as consumed; if pumps are placed with 3 speeds, better.

These small pumps consume about 70w , and move up 3 mt3 hour. Supposed to put one in the suction, another at the beginning of the circuit and at the end, you get the same result, but with 210 watts of consumption (and I think the same).
If the system well work for you - tell us - and in a third phase, install a pair of solar panels to generate the electricity needed to move pumps underfloor heating (which would have to be 300W peak minimum total, so you can move also in the morning and evening, when the sun gives them "glancing" at times that also heats but less, and also take the heat). leveraging it for heating in winter

The underfloor heating works with a flow temperature of 35 °, so that if you connect the exchanger to the return of winter heating circuit , also activating the pump heating, safe grubbed prevent the boiler during the day, reducing consumption gas.
His idea is to replace the coils of two kits of 15 vacuum tubes, less thermal inertia (less water and more pickup surface) and lower power consumption (70W with 1 pump enough), with which not only heat up nice pool, they would get more performance for home heating.

Jordi finally I said "Nothing, just say I'm very happy, thanks to your blog I started all this, and with 4 hard think I got what I wanted."

It has been my pleasure to guide (two heads are better than one) , we are happy to follow your progress with the system every year.

This is the strength of renewables, the only future of energy, contrary to some energy-lobbies.

More data: 

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