Solar Water Heater

Abstract

A lightweight and low cost solar water heating apparatus which is comprised of an insulated container with a transparent cover enclosing a folded tank is provided. The tank is comprised of a lightweight material which is folded into a shape that allows any seams in the material to be held above the surface of fluid within the tank. The folded tank further contains a working fluid which absorbs solar energy when the tank is exposed to sun light through the transparent cover. A length of lightweight pipes is coiled in a serpentine fashion within the folded tank and is surrounded by the working fluid. Pressurized supply water flows through the serpentine length of pipe and absorbs heat from the working fluid as it travels through the folded tank. The heated supply water is then used as pre-heated supply water for a standard hot water heater.

1 . A solar water heating apparatus comprising:
 a container comprising:
 a cover which allows solar energy to enter said container, 
 a plurality of side panels, and 
 a bottom panel; and 
   an inner tank contained within said container which is exposed to solar energy through said cover and which is substantially filled with a working fluid which absorbs heat from said inner tank; and   a tube opening into said inner tank which allows said inner tank to be substantially filled with said working fluid and allows said inner tank to be vented; and   a supply-water pipe, which runs from the exterior of the container to the interior of the inner tank and is substantially surrounded by working fluid within the inner tank and has sufficient strength to withstand pressurized fluid within, comprising:
 an inlet exterior to said container which allows cool supply water to enter the system, 
 a length of pipe, and 
 an outlet exterior to said container which allows heated supply water to exit the system; 
   whereby solar energy enters said container through said cover and heats said inner tank thereby heating said working fluid thereby heating said supply water running through said length of pipe.   
     
     
         2 . A solar water heating apparatus of  claim 1  wherein said cover, said side panels and said bottom panel of said container are further comprised of an insulating material or materials. 
     
     
         3 . A solar water heating apparatus of  claim 1  wherein said inlet and said outlet of said length of pipe enter and exit said inner tank above the surface of the working fluid which substantially fills the inner tank. 
     
     
         4 . A solar water heating apparatus of  claim 1  wherein said inlet and said outlet of said length of pipe enter and exit the inner tank below the surface of the working fluid which substantially fills the inner tank, thereby allowing the system to be cleaned out. 
     
     
         5 . A solar water heating apparatus of  claim 1  wherein said inner tank contains a heating element. 
     
     
         6 . A solar water heating apparatus of  claim 1  wherein said inner tank is comprised of a foldable material, said foldable material being folded into a tank in which all seams are above the surface of the working fluid which substantially fills the inner tank. 
     
     
         7 . A method of constructing an inner tank of  claim 1  comprising the steps of:
 folding a rectangle of foldable material in half lengthwise while maintaining curvature around the fold and drawing the lengthwise edges towards each other; 
 folding the widthwise ends of said rectangle by drawing the center point of said widthwise edges of said rectangle between said lengthwise edges so that said center points of said widthwise edges are aligned with said lengthwise edges when said lengthwise edges are drawn together; and 
 sealing said lengthwise and said widthwise edges together.