bitdog
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Joined: 13/11/2016
Location: United StatesPosts: 15 |
| Posted: 07:30pm 28 Nov 2016 |
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DIY Solar Water Heater (SWH) Living off the grid, I put 100' of 1/2" black Potable NSF polypropylene/polyethylene tube/pipe coiled on my roof and every 20 minuets I could take a hot shower. Like a garden hose gets hot in the sun. I used bailing wire to hold the coil on the roof facing the noon sun, with the coils about 6 inches apart so the shadow of one didn't hit the next when the sun was at an angle. The .5" ID was small enough that my 10 lbs water pressure pushed any air out of the coil. It worked so well that I was going to get a 300 foot roll for $99 and install that. $100 for free hot water forever seem like a reasonable price to me. Thin pipe heats water quicker, but holds less PSI. Freezing doesn't crack/break it, but I blow out the water every fall with the air hose, & start it up again in the spring. If I was going to make a SWH to heat a water tank in the house, I would build a level 12' x 16' platform of 6 sheets of plywood painted flat black, above the ground, below the house on the sunny side. Then coil tube 1" ID 300 feet on it. One nail on each side below the pipe height, bend in to hold it in place. Then lay any glass from old windows on top of that to keep the cooling wind off & the heat in. Then the insulated water tank would be above the coil and inside the house. From the very bottom of the tank, an outlet pipe 2", ball valve, cold water in T, and line down to the coils center spiral by going under the platform to a hole in the center. Then the outside of the spiral SWH coil goes up insulated in the house to the tank 6 inches below the top. Domestic hot water out of the top. I get free discarded 120 gallon stainless steel water tanks called boiler mates, and weld on the threaded end of a stainless pipe short nipple 4" long cut in half. Cover the threads to protect them to arc weld, drill/file out tank/pipe hole after. Out of the very top comes air and water until there is no more air left in the system. Coil coming in 6" down allows air to collect by outlet while the coil can still flow. Heat rises, cold settles, no pump needed. The low flow pressure from heat means that air bubbles can stop the flowing process. Close the bottom ball valve and open up the outlet valves and incoming water pressure will push any air in the coil up to the tank and out. The tank plumbing described works for wood stoves or any off grid heat coil source. The main idea is that: from the bottom of the tank the line ALWAYS GOES DOWN, until it ALWAYS GOES UP, so no air can be trapped. The BOTTOM of the line goes UP to the heater, then UP to the tank. I put the cold in T down from the bottom of the tank a ways so incoming cold water pushes half into the tank, & half into the coil. This system could make 5 to 10 gallons every half hour for 7 hours a day for 35 to 70 gallons of water hot enough to burn your skin with an open air coil. With glass on top of the coil, you might make steam, or burn the lips off your face getting a drink of water from the faucet. Kids could get hurt. There are auto temperature bi-metal mixers available that can be adjusted to control output water temperature. This would be advised for kids & blonds. Plus, with all the savings, your beer budget could be increased. I hope this helps some one, some where, some how.
Bitdog
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