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Thread: DIY Solar heater

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    DIY Solar heater

    I'm looking at a Sungrabber type system for my pool, but my main questions are 1) isnt plastic a insulator and not a very good conductor of heat. 2) Why not just "coil" or parallel a few 100" lenghts of black garden hose on a pool deck. I would think the black rubber would absorb/transfer heat better than any plastic pipe and on a concrete pool deck.

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    mas985's Avatar
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    Re: DIY Solar heater

    1) Plastic is a good electrical insulator but if it is black, it is also a very good thermal conductor.

    2) Solar panels are all about area. By the time you make a panel large enough, the cost of all that pipe is likely to be nearly the same as the solar panel and the solar panel will be a lot easier to install. The material used matters less than the color. There are panels made of both plastic and EPDM, a rubber material, and they both work well.
    Mark
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    Re: DIY Solar heater

    I really like our solar bear panels...that said +1 to what Mark said. One 4x20 panel easily has 30+ tubes that the water passes through x 20ft each = alot of tubing if you were to DIY and would not be able to fit it in a 4x20 area.

    Ever touch a black trash bag that's been sitting out in the sun? When the water is running through the panel it's cool to the touch, but feels hot just like the trash bag when the pump is off and the panel is in full sun
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    Re: DIY Solar heater

    Yeah, I was lookin to be lazy and see if anybody had built a solar heater with garden hoses. The real question I have about the plastic mat styles are about durability. Is 2-3 seasons is what you would get? If you get a leak then what? Is there a mil thickness? Where is the best place to buy, I'm looking for 2 - 4X20 panels for a 20,000 gal 16X32 rectangle

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    solarboy's Avatar
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    Re: DIY Solar heater

    I'm about to build one with 4kg/cm2 pressure rated irrigation pipe. Because I'm in an agricultural area and in the trade building a spiral panel myself works out about the third the cost for the same area and I think mine will be a lot tougher but possibly slightly less efficient in use of space. The cheapest panels I can get here are around 200$ for a 2' x 20 ' panel. I'll be starting the panel itself in about a month, I've already fitted the 3 way valve etc. I'll let you know how I get on.
    Self built 5500 gallon bare concrete (temporarily) pool with limestone coping, Pentair Swimmey 1/2 HP pump, Triton sand filter with DE, Simpool peristaltic muriatic acid pump with pH sensor and Monarch SWG. Home made solar heater with Pentair Compool control panel and 3 way valve. 1 skimmer, 1 main drain, 2 returns, 2" plumbing, Hayward auto fill valve.

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    Re: DIY Solar heater

    Spirals are generally much less efficient in terms of heat gathering. You want as many parallel runs of pipe as possible, while spirals are typically done with a single length of pipe. Optimal efficiency occurs when the flow rate is as high as possible and the heat gain in minimal. Single long runs of pipe dramatically increase the flow resistance, lowering the flow rate. They also allow the water to heat up more in a single trip through the system, lowering efficiency.
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    Re: DIY Solar heater

    I would have thought it would be the other way around. That spirals would retain the heat. On the mat style do you want as high a flow as possible?

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    mas985's Avatar
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    Re: DIY Solar heater

    You don't want the panels to "retain" heat, you want them to transfer heat to the water as quickly as possible. The reason panels are more efficient with higher flow rates is because the water temperature in the panels is kept as low as possible and thus the heat loss from the panels will be minimized. The higher the water temp in the panels, the faster they lose heat to the surroundings.

    As for flow rates, most panels will peak in efficiency around 0.1 GPM/sq-ft.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: DIY Solar heater

    Quote Originally Posted by APrime
    Yeah, I was lookin to be lazy and see if anybody had built a solar heater with garden hoses. The real question I have about the plastic mat styles are about durability. Is 2-3 seasons is what you would get? If you get a leak then what? Is there a mil thickness? Where is the best place to buy, I'm looking for 2 - 4X20 panels for a 20,000 gal 16X32 rectangle
    The rule of thumb around here is to have equivalent solar panel covetage for about 80% of your pools surface area. Two 4X20 panels aren't going to be enough for your pool.
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    Re: DIY Solar heater

    Quote Originally Posted by carlscan26
    Quote Originally Posted by APrime
    Yeah, I was lookin to be lazy and see if anybody had built a solar heater with garden hoses. The real question I have about the plastic mat styles are about durability. Is 2-3 seasons is what you would get? If you get a leak then what? Is there a mil thickness? Where is the best place to buy, I'm looking for 2 - 4X20 panels for a 20,000 gal 16X32 rectangle
    The rule of thumb around here is to have equivalent solar panel covetage for about 80% of your pools surface area. Two 4X20 panels aren't going to be enough for your pool.
    Ditto...anything will help, but you are looking at 3-4 panels on a 20K gal pool. And using a solar cover to retain the heat generated during they day is essential.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    solarboy's Avatar
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    Re: DIY Solar heater

    I am planning on 8 parallel 5/8" pipes running around together with a total area of around 160 square feet. I totally understand the premise that it's better to have a large quantity of moderately heated water than a small quantity of highly heated water, as this would lose more to and from the panels as the temperature differential is so high. I was more thinking it would be less efficient due to the shape not fully occupying the rectangular shade it will be on.
    I plan to take some very detailed measurements which I will post here.
    Self built 5500 gallon bare concrete (temporarily) pool with limestone coping, Pentair Swimmey 1/2 HP pump, Triton sand filter with DE, Simpool peristaltic muriatic acid pump with pH sensor and Monarch SWG. Home made solar heater with Pentair Compool control panel and 3 way valve. 1 skimmer, 1 main drain, 2 returns, 2" plumbing, Hayward auto fill valve.

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    Re: DIY Solar heater

    Quote Originally Posted by mas985
    As for flow rates, most panels will peak in efficiency around 0.1 GPM/sq-ft.
    That works out the same as the Australian standard which recommends between 1.8LPM and 4.8LPM per m2.

    This is one guys home made panels. I don't know enough math to tell if his calculations are correct, but I found it an interesting read.

    My gut feeling is that unless you have access to very cheap black tubing, it's better to get some premade panels.

    If going the homemade route, is polyethelene the best plastic to use? As opposed to polyurethane, nylon or something else?

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    mas985's Avatar
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    Re: DIY Solar heater

    For the life of me, I can't imagine how that would be cheaper than a premade panel. Plus, spirals are not very space efficient. Nearly 1/4th of the area is wasted instead of generating heat.
    Mark
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    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: DIY Solar heater

    Well a 40 sq ft panel here is 264$ (189€). I can get 38 x 20 foot lengths of 5/8 " (760 foot) for 129 $ (92€) leaving me 135$ for 16 clamp brackets to go on about 1 metre of 2" "manifold" at either end. As these brackets cost me about 50c each and the pipe about 2 dollars I save 125$ just on the one panel. In that I intend to have a panel about 3 times this size I hope to save around 375$ for an afternoons work. And the panels I saw for sale looked liked they'd only last a season or two while the irrigation pipe and fittings lasts decades.
    Self built 5500 gallon bare concrete (temporarily) pool with limestone coping, Pentair Swimmey 1/2 HP pump, Triton sand filter with DE, Simpool peristaltic muriatic acid pump with pH sensor and Monarch SWG. Home made solar heater with Pentair Compool control panel and 3 way valve. 1 skimmer, 1 main drain, 2 returns, 2" plumbing, Hayward auto fill valve.

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    Re: DIY Solar heater

    4 Panels @ $230.00 = 920.00, 4-1000' rolls of .700 PE @80.00ea=$320.00 Devils advocate, How are the panels cheaper?

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    solarboy's Avatar
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    Re: DIY Solar heater

    Quote Originally Posted by Jimmy_from_NZ
    Quote Originally Posted by mas985
    As for flow rates, most panels will peak in efficiency around 0.1 GPM/sq-ft.
    That works out the same as the Australian standard which recommends between 1.8LPM and 4.8LPM per m2.

    This is one guys home made panels. I don't know enough math to tell if his calculations are correct, but I found it an interesting read.

    My gut feeling is that unless you have access to very cheap black tubing, it's better to get some premade panels.

    If going the homemade route, is polyethelene the best plastic to use? As opposed to polyurethane, nylon or something else?
    Now figure does help me, so I will probably need to have 32 runs of shorter pipe to fall in the middle of that spec. The pipe I'll be using is polyetheylene by the way.
    Self built 5500 gallon bare concrete (temporarily) pool with limestone coping, Pentair Swimmey 1/2 HP pump, Triton sand filter with DE, Simpool peristaltic muriatic acid pump with pH sensor and Monarch SWG. Home made solar heater with Pentair Compool control panel and 3 way valve. 1 skimmer, 1 main drain, 2 returns, 2" plumbing, Hayward auto fill valve.

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    mas985's Avatar
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    Re: DIY Solar heater

    My comments were directed toward the design shown by Jimmy_from_NZ.

    http://rimstar.org/renewnrg/solar_pool_ ... diy_fp.htm
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: DIY Solar heater

    I know this is an old thread put has anybody here tried this stuff ?
    http://www.homedepot.com/webapp/wcs/sto ... RRWidgetID
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