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Evacuation Tubes for Solar Heating a Pool


Louw
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My brother is busy getting quotes for heating a pool.  His house is a double story house, with high ceilings, so about 8-9M above the pool.

The guy giving him the quote indicated that it is to high for a normal swimming pool pump and suggested a separate pump, circulating the water through 3x20 Evacuated Tubes.

My calculations says it won't be effective:

800W/h/m2 x 2m2 x 3 = 4,800W per hour = 24,000W per day

24,000W / 1.17 / 42,000liters = 0.57C increase per day

Am I wrong in saying that it won't help at all????

 

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Agreed. EV tubes are not designed for that.

Little titbit. I once read of a DIY guy who wanted to heat his pool. So off he went to the Co-op and bought 1km of that cheap black pipes you get there, very cheaply, knowing full well it will not last long in the sun.

He promptly made one huge rolled-up circle, on the ground, and connected his pool pump to it on side, other side into the pool. 

After a day or so he shortened it very quickly, I think to 50m or something, after the pool water started getting extremely hot.

 

To get the water pumped to the roof is a wee bit of an issue, but can be overcome with non-return valve strategically placed for once the water comes down other side, the pump does not work as hard anymore. But you still need a powerful pump.

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I agree ev tubes are at risk of corrosion from the chlorinated water, would not go this route.

Checkout http://www.swemgat.co.za I will try and find the link and add it to the post but they use a membrane which looks like corrugated cardboard which the water is pumped thru and this works really well and is very durable.

Maybe contact them for some free advice.

http://www.swemgat.co.za/pool-heating-swimming-pools-pretoria-centurion-middelburg.html

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I've used about 400m x 15mm irrigation pipe. This is a pic of the initial installation in 2006. Initially I had 21 coils each connected between the 2 headers, but soon realised that the pool pump was not pushing water through all the coils and then "rewired" all the coils to only have 7 parallel "strings" of 3 coils in series each. A bit later I've replace the headers to get rid of all the unused blanked-off saddles. 2 years ago some of the black pipe stated to get brittle and leak and I've replaced some of it, but some of it is still the original pipe after 10 years - that was the cheaper pipe guaranteed only for 5 years. :)

It takes less than 3 minutes to replace the hot water in the pipes with cooler water from the pool so I've used one of the cheap (R100) digital timers with 8 programs to control the pool pump, switching it on 8 times a day for 3 minutes at a time at intervals of about 30 minutes - that is a total pool pump run time of 24 minutes per day. In mid-summer I bypass the heating coils because the water temp easily goes from 20°C to about 33°C in a day.

Must admit it is only a 5kl splash pool, but if you increase the total length of pipe etc. you might be able to achieve the desired water temp in a bigger pool as well.

pool heating.JPG

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It would seem that the installer is not very familiar with basic knowledge of the issue. I has a double story house in Randburg and the pump had no problem circulating the water. Also evacuated tubes is total overkill. All you need are the flat plastic collectors, maybe five or six. The swimming pool pump only circulates the water as both the inlet and outlet is beneath the surface of the pool water. I used a bubble blanket and in four days the temperature of the pool was 34C.

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