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

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The super-insulated exchanger tank was then carted over to the home of Butch and Larry Goodwin (two of MOTHER's helpers) and plumbed up with copper tubing to the Hotpoint refrigerator door collector, a second collector built from a Coldspot refrigerator door and heat exchanger, a Grundfos pump, a Hawthorne controller, and the waterlines for the Goodwin's house.

And what happens now is the controller constantly monitors the tempera. ture of the antifreeze in the collectors and the water in the exchanger tank. And whenever the first is at least 3°F warmer than the second, it turns on the pump and circulates the hotter antifreeze from the collectors through the exchanger tank's central stack (where the hot fluid gives up some of its heat to the surrounding water) and back again. The controller also runs the pump at a slower speed when the collectors are only slightly warmer than the storage tank ... but at high speed when the sun is really blazing and there's a great deal of trapped heat in the collectors to transfer to the exchanger drum.

An ordinary paint can with a plumbing connector soldered to its bottom serves as both an expansion tank and a filter spout on the "closed loop" of circulating antifreeze. The system is filled with a 50/50 solution of water and propylene glycol ... and propylene glycol (which is used to winterize the plumbing fixtures in motor homes and camping trailers) was chosen because it's non-toxic and will not contaminate the Goodwin's household water supply if the stack inside the system's exchanger tank ever develops a leak.

The total cost of this solar water heating system (which now heats most of the water used by a family of four) was $173.04 ... and we'll put the rig up against manufactured units costing anywhere from $500 to $1,500.

ANOTHER DESIGN

Nobody could have called us quitters if we'd stopped this particular set of experiments right there. But once we'd gotten that far with an active solar water heater scrounged up largely from recycled refrigerators and other salvaged parts ... well, we'd begun asking ourselves why we couldn't cobble together a passive system from mostly the same kind of materials.

So MOTHER's Little Elves selected a relatively tall General Electric fridge from her large stock of old freezers and refrigerators (see sidebar) and removed its compressor, heat exchanger coils, motor, and other hardware. Then they stripped out all the unit's shelves and racks ... even its lining and insulation (the insulation was carefully set aside for later use). The lining—but not the insulation—was also taken out of the reefer's door.

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