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How to Make a $5 Solar Water Heater From Junk Fridge


backoffridgeI mentioned in an article last summer that most Israelis have solar water heaters on their rooftops, and thus they save a lot of energy during the summer. In fact, the idea of heating the water in a boiler is not new, I had more than a dozen showers in my grandparents’ backyard, during some hot summer days in my childhood.

One simple way of making water hot has been perfected by a blogger on thesietch.org, and it relies on a simple and easy to find piece of junk: an old refrigerator!

Other components are: wood, for making a frame, glass (not plexiglass), hoses, a rubber door mat, a reflexive aluminum foil, scotch tape and glue, or silicon. Eventually, you’re going to need some screws.

Because it’s black, the refrigerator radiator heats faster than other materials. This also happens because of its tightness. The inventors who made this “instant” solar water heater want to make another one, that transports the water by thermal convection and recycle it, until it reaches the desired temperature.

The entire solar water heater project costs less than $5 and can save you of a lot of electricity, reflected on your bill.

It’s easy to do. You may go to their site or watch the gallery below, because it’s self-explanatory:

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  1. I did this years ago, EXCEPT i cast the radiator in concrete and painted the slab Flat Black. Te idea is not as easily executed as a 100 foot coil of black tubing in the sun light – see: solar pool heaters.

    • My thoughts are:
      1. Who wants to bathe in water ran through and heated in a car radiator or an old freon tube off of a refrigerator. Think of the contaminates that will be absorbed into the water. These contaminates will then be absorbed into the skin.
      2. If the fridge isn’t working chances are there is no freon in it anyway to be released into the atmosphere. (I’m not sold on man being able to change the temperature of the world anyway.)
      3. Not sure where the door mat listed in the parts list is at. If it’s black I would put it under the coil and do away with the aluminum foil.

  2. Just love this! I wish I had the ingenuity and ability to transform an outmoded product to a useful pieced of equipment. I often have flashes of ideas, but then lose sight of when it gets down to the physical completion and execution.

    • First of all, you need efficiency in heating the water. What greater efficiency can you have than that of a thin, black pipe? The hot water in the barrel gets hot after a few hours (I know that from experience), but this kind of setup heats it almost instantly. For example, leave a hose (not a black one) in the sun for 2 minutes. I guarantee you won’t want to bathe in that hot water from it!


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