DIY Solar Pool Heater
Rob A's (Im)personal Blog.
Friday, June 2. 2006
Last year I decided to make a solar pool heater. The main idea came from reading a variety of forums, old Mother Earth News articles, and checking out some old newsgroups. It seemed that others had had some success creating solar heaters in a variery of methods, from something as complex as a custom built metal heat exchanger to something as simple as a bale of irrigation hose sitting on a slope.
I decided to aim somewhat inbetween these extremes and came up with a solar "panel" consisting of a 4'x4' plywood sheet on a frame with as much irrigation hose as I could coil onto the surface
I've added a diagram to show the piping clearly, and added a bit more description at the end of the article...
Basically, it consists of about 200' of irrigation hose held to a 3/4" plywood 4x4 sheet with pipe brackets screwed down. The whole thing is propped up with legs at more-or-less the optimal angle for my location, and pointing more-or-less south. The inside of the frame was painted flat black, and the copper pipe brackets were painted flat black as well, after the thing was together. I put it on patio bricks this year to make it easier to mow around Click any of the small images for a full size in a new window.
Here is the 'T' off the pump. This is after the chlorinator, to hopefully keep the nastiness build-up in the hose away. I also added a ball valve in the line, which is super helpful in keeping the flow through the heater to a trickle. This allows the water to get hotter in the pipe, and maintain some thermal mass.
The back. Note the lovely collapsible legs for easy winter storage...
And always inelegant, the tie-wrapped outlet hose. I keep meaning to fabricate a nice contoured pipe that can come up the side, around the cap and point down inside at the wall so no water ever gets on the solar blanket, but just don't seem to get around to it.
Lastly, a couple of closeups of the coil itself. The first shows the final elbow that goes through the plywood and out. I couldn't get the irrigation hose coiled any smaller without it starting to kink, so this is where I stopped.
When I started I kept each pipe clamp with its own screws. By hand, and my cordless drill tended to overtighten the screw and I was afraid I would damage the pipe with the metal bracket. By the time I had gone around two or three times I realized I could share a screw between two pipe clamps. The other option would have been to use metal strapping.
Under noon sun, the water coming out is about 2C warmer than the inlet with the flow I valve down to. After one day of sun it pulled the pool up from 18C to 22C (it was 30C out that day), and in three days I had the pool at 28C. I am still looking for a 4x4 plexiglass to cover the coils, as I know allot of heat is lost if there is any wind blowing across them, at all.
People have asked for a better diagram showing how this is connected, so now that I have played with Inkscape a bit more, I doodled up the following:
The normal pump flow follows the blue line. Water is sucked from the skimmer by the pump, pushed through the filter, through the auto-chlorinator, then into the pool. The ball valve T I added is after the chlorinator. When in bypass, all the water flows as if there were no heater. I turn the ball valve enough to allow some of the water to flow through the heater. I don't push it all through the heater, as it puts too much stress on the pump. I just keep adjusting it while watching the pressure gauge on the filter, and stop if it starts to move up. Hope the extra explanation was useful.
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