DIY EMT Solar pool heater

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  1. pishta

    pishta I know I'm right....

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    Throwing this out to see if it is viable. 100 feet of 1/2 EMT is 26 bucks at Homey Depot. 5/8 hose has an ID of 1/2 and my 550 gallon pool already has a 350 gph pump for its filter. I was thinking of cutting the 10 footers in half to give me 20 5 foot sections. mount them to a 4X4 plywood base with foil glued to it shiny side out with a 2x4 as a riser on each side. Use sections of hose at 180's to make the back and forth connectors. Spray paint the whole tubing and hose run flat black and plumb it from the filter pump back into the pool. Lay it facing up next to the pool at the slightest angle just above the pump level so its not fighting the smallish pump. Do you think its worth $30 in parts or would it just be a waste of a saturday? Wonder what the temperature delta would be, or would I just be cooling black pipe? Ambient air temp is gonna be about 80F and it will get direct sun about 7 hours a day. Filter Pump is on the whole time its light out. Current water temp is 66F, chilly even on a hot day. I always liked turning on the black garden hose and rinsing off for the first 30 seconds out of the pool at my parents house, Almost hot water in that black hose!
     
  2. scott657

    scott657 Well-Known Member

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    until the galvanizing flakes off and clogs up the works.Use copper
     
  3. pishta

    pishta I know I'm right....

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    ^^ interesting.......^^
    • Interior coated provides a smooth and fast wire pull...would this help any?
    PVC is the same price, would it conduct heat any better?
     
  4. scott657

    scott657 Well-Known Member

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    and then the rust
     
  5. pishta

    pishta I know I'm right....

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    seasonal,maybe another 2 months, not expecting it to last forever. How long you think it would survive? 30 bucks is Dinner at In-N-Out
     
  6. scott657

    scott657 Well-Known Member

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    use PVC pipe (plumbing and fittings) I think you'll get better results
     
  7. Dana67Dart

    Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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    I think you would be better off without the foil. You want to absorb radiant heat.

    They make metal panels for radiant heated floors that allow you to snap a pex like tubing into.

    I have seen the same thing set to face the sun and painted flat black. You will get a delta but might need to only run a percentage thru the heater element.
    I say go for it.
     
  8. kursplat

    kursplat FABO Gold Member FABO Gold Member

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    don't forget the $30 in hose clamps :lol:

    move to the valley, the pools are nice and warm here. you're too close to the ocean :D
     
  9. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    I would not use EMT. Pishta I KNOW you are a smart guy have you google searched efficient solar collector designs? I once played with the idea of building something. The truth is I don't care, anymore. The sun energy "up here" in the N end of Idaho is a LOT less than down there, so there's that.

    But there is certainly differences to be had in design. Also don't forget that if you don't have a method of drainback, the system can radiate heat OUT of the system at night as well LOL
     
  10. my68barracuda

    my68barracuda Well-Known Member

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    I would have a concern over the length added to the pump feed lines. The pump on my pool is high volume and low pressure. If the added lines are smaller that the existing lines and considering all of the 90 degree turns being added, you may reduce flow considerably.
    We use a solar blanket to warm our pool. It is very effective in raising the water temperature in the day time and not loosing warmth at night.
     
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    • trapster

      trapster Well-Known Member

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      I think if you look around you can pick up used solar pool panels really cheap. That being said I was thinking of running the water through 4" corrugated drainage pipe. I think 100 ' will cost you around $60, its it already black just coil it in a big circle and put it on the roof. with a nice waterfall on the other end.
       
    • DFX 340 Duster

      DFX 340 Duster FABO Gold Member FABO Gold Member

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      Pishta, I used a pool cover to heat my pool. I bought one that was like bubble wrap and I cut it to fit the shape of my pool. It was very effective in trapping the heat produced by the sun.
       
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      • Kendog 170

        Kendog 170 Let the boy go !

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        My brother does this with some black garden hose in New England Ma. It does help. He just lays it out by the pool (Direct sun ) not sure what pump he uses. As mentioned not a night or it will cool your pool.
         
      • YY1

        YY1 Well-Known Member

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        I think the "factory" solar pool heaters are much smaller tubing and many more of them to increase the exposure of the area/volume of water in the tubes to light/heat.
         
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        • rklein383

          rklein383 Well-Known Member

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          • famous bob

            famous bob mopar misfit

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            PVC will degrade in sunlight after a while , PEX will too .
             
          • JDMopar

            JDMopar Well-Known Member

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            @famous bob How about ABS pipe? It's already black. If @pishta gets a few seasons out of it before the UV rays eat the pipe, he has achieved his goal and can replumb it. I know a guy who built an outdoor shower, and used the coiled black water line like pictured above. I understand Pishta wanting to use the foil underneath the pipe he chooses, to reflect heat to the bottom side of the pipe also. The guy I know with the outdoor shower pumps his solar heated water into an old water heater tank that is inside a box that is 2' bigger, and has sand poured into the box to surround the tank and hold the heat in. He is planning to upgrade that to spray foam instead of sand, to hold the heat in longer.
             
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            • YY1

              YY1 Well-Known Member

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              Anyone got a DIY solar water heater setup?

              The WH is one of the most energy consuming appliances in most homes.

              ...and a VERY good candidate for a stand-alone solar installation.
               
            • pishta

              pishta I know I'm right....

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              I like the coiled PEX design, but the lexan would cost me so Im gonna attempt the EMT design. If I fail, I got 20 5 foot lengths of EMT out of it.
               
            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              Just a question...

              What does chlorine do to the galvanized coating and that will go into the water that you and kids are swimming in and occasionally injesting.
               
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              • Jimacuda

                Jimacuda Well-Known Member

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                use the money you'll be spending/wasting on emt and the rest of what youll need towards a solar cover.
                doesnt get much simpler than one of those and they arent expensive.
                 
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                • brummett

                  brummett Well-Known Member

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                  I'll also suggest going with the solar cover, too. At one time I'd planned on making something similar out of copper tubing and some old windows I had stashed away, but I was worried the chlorine in the pool water wouldn't react well with the copper, and I can't imagine galvanizing on the EMT would work any better.

                  The cover I have looks like really heavy duty bubblewrap and works great. It warms the water in the daytime and keeps it from evaporating and cooling at night.
                   
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                  • Phreakish

                    Phreakish Well-Known Member

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                    *I haven't double checked these numbers, but it seems to be close - my math could be off...

                    Typical solar insolation is around 7 kwh/sq meter in your area in the summer. Or 7k Joules per second.
                    Water requries 4.2k Joules per kilogram per degree C.
                    550 gallons is 2082 kilograms. From 66F to 80F is 16F difference or 9 degrees C.
                    This nets a requirement of 78,699.6k joules to heat the 550 gallon pool. Assuming a solar insolation of 7kwh/sq meter, then a 1 sq meter heater at 100% efficiency would take 11,242.8 seconds to heat the pool - or approximately 31.23 hours. Obviously this won't work because you only have ~12hrs worth of insolation, and likely a lot less 'effective' hours depending on shade/angle.
                    So let's assume that the height of insolation will last approximately 4 hrs, then we need 7.8 times more area. So now the solar heater has to be ~8 sq meters. But a solar heater is not 100% efficient, and will need some excess capacity in order to deal with wind, shade, etc. At 71% efficiency (a figure I found on some random solar heater page) that brings us to 11sq meters or approximately 100 sq ft.
                    With 10ft long conduit you'd need 10' worth of width as well - at 1/2 diameter that's 240 10' lengths of conduit, or 2400' of conduit, or $624 worth of conduit prior to hoses, connections, etc.

                    Even trying to use all 7 hrs, this would only cut the system to ~50 sq ft and ~$312 worth of conduit.

                    Now, this assumes the pool will lose all heat at night, every night. Which isn't the case. This also makes a ton of other assumptions which are likely not accurate, but is a good conservative sizing exercise. Based on the roof-mounted pool heaters I used to see in Vegas all the time, this size seems fairly reasonable.

                    If it were me, I'd buy a few rolls of HDPE piping and try to roof mount. 1" non-potable HDPE is about $55 for 300 ft, or about $220 for 1200ft worth, but there's still the cost of assembly since HDPE doesn't like to make bends. I'd build it with a bunch of T's to make a radiator-like layout, but even at 20' wide that's 120 T's. Or it may be possible to just lay out a flat coil or two, which would reduce the number of fittings. Roof mounting would still be a good idea since it will help cool your roof while heating your pool.
                     
                  • scott657

                    scott657 Well-Known Member

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                    I’m out ^^^^
                     
                  • DFX 340 Duster

                    DFX 340 Duster FABO Gold Member FABO Gold Member

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                    Being an aerospace engineer I went through those calculations for my 33,000 gal pool. Talked to some guys at the pool supply stores and they all told me to do the solar cover. I put it in place and in about three days the pool was perfect temperature. I then learned to remove the cover on a regular basis depending on the season or the pool would heat up too much and destroy my chlorine content. The cover allowed me to use the pool from March to November without using my gas heater. I used the heater for the jacuzzi of course.
                    An engineer friend built his own radiator and valve system for his pool because he didn’t want to spend the few minutes it took to remove a cover. He spent a lot more money than I did but we achieved the same result.
                     
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