http://www.edsanders.com/solar/hotwater.htm -- Lawrence F. London, Jr. mailto:london@sunSITE.unc.edu mailto:llondon@bellsouth.net http://sunSITE.unc.edu/InterGardenTitle: edsanders.com - Solar Hot Water
I've had an interest in solar energy since the early '70's. Finally this summer (1997) I got around to building a solar collector. I've been collecting materials for a solar hot water heater for over 15 years, but never took the time to put them together until this summer.
The heat exchanger is a 4 foot by 6 foot radiator that was supposed to be destined for use in a nuclear power plant. It consists of 3 inch diameter headers at the top and bottom with half inch copper pipes spaced a little over an inch apart covered with aluminum fins. While in transit some of the fins were bent so they couldn't use it. I bought it from the trucking company salvage store for a hundred bucks. The Kalwall glazing was bought at a yard sale for 15 bucks. Miscellaneous plumbing fittings, barbecue grill paint and wood were about another hundred bucks.
It took most of a day to assemble, no design was drawn up, I just sort of "winged it". There is nothing fancy about the plumbing, I just take the water supply to our electric hot water heater and run it through the collector first. At noon the day after making it we were getting 189 degree (F) water at the outlet. There is a "blowoff" on the radiator to protect the system from excessive pressure buildup. It will be drained before the first hard frost.
The top header before return line to the hot water heater is connected.
The top header to the right.
The bottom header before connecting the feed pipe from the house water supply. Notice the crate section underneath. I decided to just leave this connected to the radiator to serve as a base.
Closeup of the top pipe connection. I used polybutylene with an "O" ring type adaptor. It took a bit of work to get the threaded area to quit leaking where it went into the metal. A few weeks later the heat generated loosened the polybutylene pipe where it went into the adaptor, and I had to re-tighten it. Other than that, no problems so far.
Lower inlet pipe connected.
Lower inlet pipe. Notice safety blowoff. I put it on the bottom so if it blows the water would just blast off the edge of the porch roof.
Detail of top return pipe connected.
View of bottom part of collector showing inlet pipe. The glazing is Kallwall plastic nailed over a plywood frame.
A view from the east side of the collector.
A thermometer showing the air temperature inside the collector, 187 degrees F.
The following account of solar power is from the book, "The Knowledge Library, 1919, first printing 1915.
A small plant may be made to pump sufficient water for a large tract by having a reservoir and running the pump every day when the sun shines, using the water only as needed.
Any and all kinds of minerals can be smelted, or literally "burned up", if desired. A single square yard of sunlight will melt silver, gold, glass or wrought iron to a liquid, while two yards square of sunlight will develop over 25,000 degrees, or more than 100 times as much as boiling water.
A small plant can be installed on the roof of a house at a cost of only a few dollars. Attached to the water hydrant, it works automatically and carries steam down through pipes to the kitchen, where it is attached to a steam cooker cooking a dozen different kinds of food at the same time without fire, fuel or expense, and furnishing boiling water for the bath, laundry and other purposes.
Electric power is generated by a steam engine run by the solar furnace during the daytime and stored in a storage battery to run machinery, and for heating, lighting, cooking and other purposes nights and on cloudy days. The possibilities of the solar furnace are practically unlimited.
Recently most important sun-power plants have been installed, one near Philadelphia and one at Meadi, near Cairo. Egypt. The Egyptian plant promises to be very important. The proprietors expended very large sums of money in investigation and preliminary work. They think they have solved the problem of successful application of this greatest of all natural forces. But it must be remembered that Egypt presents features that strongly assist such work, that are not present in all locations. The sunshine, for instance, is constant. Undoubtedly this plant will accomplish great results in the way of pumping water for irrigation purposes.