MORE WAYS TO RECYCLE OLD REFRIGERATORS INTO LOW COST SOLAR WATER HEATERS

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So the boys pulled the liner out of the Hotpoint's door and replaced it with the heat exchanger. Then a couple of holes were drilled through one end of the door and a couple of pieces of scrap copper tubing (also scavenged from the refrigerator) were used to extend the exchanger's coils through the insulated wall. (It was exceptionally easy to slip the recycled 3/8-inch tubing right over the ends of the 1/4-inch plumbing and solder the "splice" into a watertight junction.)

Next, six holes were drilled through both the exchanger plate and the "back" of the collector box (actually, through the main body of the old refrigerator door) and the two were fastened together with stove bolts. Some odd pieces of cardboard were then used to cover the insulation that was still exposed around the "rim" of the exchanger (this was done purely for appearances), and the heat exchanger and its surrounding paperboard trim were all painted flat black.

Finally, two pieces of glass were cut to fit as a "top" for the collector box. The panes were mounted just under the old door's rubber gasket (how's that for having just what you want just where you want it?) and seated in place on a bead of silicone caulking.

MOTHER's crew of merry experimenters then hooked their new collector to a small pump and circulated a strong detergent solution through the flatplate's plumbing to flush out any residue Freon. After that, they connected the collector/pump to a barrel of water, aimed the solar panel at the sun, and turned the pump on. Sure enough! The circulating water immediately began picking up Btu's as it passed through the collector ... and a thermometer soon showed that those calories of heat were, indeed, being transferred to and stored in the drum of water.

AN IMPORTANT POINT: Please note that—due to the small cross section and serpentine pattern of the tubing in the old Hotpoint's heat exchanger—this flatplate collector was not suitable for use in a "passive" thermosiphoning water heating system. (See the interview with David Wright in MOTHER NO. 47 for an explanation of a passive solar heating system's operation.) However, merely by hooking a small pump to the flatplate and pumping water through the collector (and a great many "real—solar panels are set up to work exactly this way), MOTHER's scavenged-from-a-refrigerator-in-a-couple-of-hours collector was made to work just fine.

ANOTHER INNOVATION

So far, so good. But our researchers hadn't even gotten started. As long as they already had the makings of an exceptionally low-cost active solar water heating system on their hands, they figured they might as well go ahead and do the job up right. With antifreeze (so sub-zero temperatures wouldn't bust their solar panel or the plumbing attached to it) circulating from the recycled collector to an insulated exchanger tank ... and a separate set of waterlines (cold in and hot out) leading from that exchanger tank to somebody's home.

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