Everyone knows that refrigerators are good for storing cold. What everyone doesn’t know is that fridges are also very good for storing heat…as Miles K. Free III points out in the following report.


Ever go riding or walking through the countryside … and discover an old, abandoned Frigidaire, Kelvinator, or what-have-you just sitting there collecting dirt, leaves, and field mice? A while ago-after I was laid off from the local steel Mill—I began to encounter so many of these derelict fridges that I actually found it profitable to load them into my pickup and sell them to the local scrap yard for $15 to $20 per ton.

For a while, I felt good knowing that I was helping to clean up the countryside, and recycle tons of valuable metals (thereby reducing the need for mining). I’ll admit, too, that I didn’t mind pocketing the few extra bucks that my “fridge salvaging” operation was netting me. But still, it was slightly upsetting to see all those once-useful appliances go on the scrap heap.

“Surely,” I said to myself, “there must be some useful function that a precision-made, well insulated ‘cabinet’ can serve.” And that’s when it hit me: Why not use an old refrigerator to store heat, rather than cold? Specifically, why not build a simple solar collector … connect it to a water storage tank … enclose the tank in a recycled fridge … and stick the whole works out in the sun to generate a constant supply of “free” hot water?

To make a long story brief, I went ahead and built just such a water heater (see the accompanying illustrations) using about $30 worth of easily obtainable materials ( see the accompanying Bill of Materials ) … and the darned thing works great! Here’s how it all went together.


My water heater’s solar collector basically consists of an insulated, 2′ X 4′ X 5″ wooden box, an “absorber plate” (some black-painted copper tubing on a black-painted sheet of metal), and several layers of plastic and glass glazing.

The “shell” of the collector was easy enough to make: All I did was nail together a 5″ X 2′ X 4′ box out of scrap lumber and wood paneling. (The exact dimensions here aren’t that important … I just made the largest box I could with what materials I had on hand. If you want to construct an even larger collector, by all means feel free to do so! )

To make my collector’s “absorber plate”, I first salvaged about 15 feet of copper tubing and after cleaning it up with sandpaper cut the pipe into 6″ 8″, 18″ and 24 ” lengths. ( See the accompanying Bill of Materials. ) Then I soldered elbows to the ends of the 6″ pieces, taking care to see that the joints faced the same direction. (I checked the elbows’ exact alignment by making sure-as I put each elbow/pipe/elbow assembly on the ground-that both “ells” touched the floor.)

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