I made these solar heaters only to measure their energy parameters, and first I made this variant from a cheap polyethylene pipe. Then I measured the energy parameters of this 2nd variant which is characterized in that its pipes lie on a black surface. This is my 3rd variant which is similar to the 1st variant, but with large gaps between adjacent pipes. Then I tested this 4th variant, and we see large gaps between its pipes, like the 3rd variant, but the pipes lie on a black surface, and its north side has thermal insulation.
The main results of my tests are described by these graphs and tables which will be explained during this video.
This is my measurement of the energy parameters of my four variants of the cheap solar heaters. However I want to clarify that I used such cheap polyethylene pipe with an outer diameter of 16 mm and a wall thickness of almost 2 mm. The Ukrainian prices of this cheapest pipe are about 15 American cents per meter, and we can calculate that complete covering each square meter by this pipe is about 10 dollars.
In addition, I painted my pipes, and now this half of the solar heater is already covered in black paint which increases the efficiency of the heater and protects the plastic from ultraviolet solar radiation.
So, a square meter of our solar heaters is several times cheaper than these traditional pool heaters, but we can see that their energy parameters noticeably better than our solar heaters. That is why our square meter will produce significantly less heat, and this is due to the fact that our black pipes do not cover the whole surface of the heaters.
For example, the pipes cover only 66 % of the surface of my 2nd variant because we see small gaps between adjacent pipes. In addition, these areas are not covered by the pipes, and I want to clarify that the coverage area is the multiplication of the pipe length by its outer diameter.
The length of the pipes of my 4th variant is even 2 times smaller, and they cover only 33 % of the surface of the heater.
My 1st variant is covered with pipes by 73 % if we think that this square is the area of the heater, and this is a fair idea if we remember how neighboring heaters are placed.
The area of the 3rd variant of my heater is covered with the pipes only by 37 %.
This table shows the heat production of one square meter of my four variants of the heaters during an absolutely sunny day in Europe, the United States and India. These are cases where the solar heaters must heat swimming pool water with a temperature of 30 ºC.
It is interesting to compare our heat production with these more durable and expensive solar pool heaters. We see that one square meter of expensive heaters produce significantly more heat, but our square meter is several times cheaper. That is why our heaters can make economic sense if we do not have a deficit of space for the location of our solar heaters.
In addition, we can remember that such heaters are sometimes used for a primitive shower. Now we see that the sun has heated the water inside the black pipes of my heater to 67 ºC when the temperature of the ambient air was 28 ºC.
This graph describes the heating capacity of one meter of my black pipe for my four variants for different temperature differences between the heater water and ambient air.
So, we see that our 3rd variant is the most inefficient use of our black pipe. Now I show one of my experiments with the 3rd variant, and this pump moves the water of this tank through our black pipe which has already heated the water to 45 ºC. But on the other hand, our 3rd variant is the best if the water temperature is noticeably less than the ambient temperature, and it can be a case of heating a pool immediately after replacing its water.
Our 1st variant is similar to the 3rd, but the gaps between the pipes are minimal. This experiment shows how my 1st variant heated 27 liters of water from a temperature of 22 ºC to a temperature of 52 ºC for 2 hours. We see that our 1st variant uses the pipes more efficiently than the 3rd because the large gap between the pipes of the 3rd variant increases their heat exchange with the ambient air, especially during wind.