Solar water heater

Abstract

The invention provides an affordable solar water heater of a simple construction and a process enabling its mass production. The heater is characterized by the tank and the collector being integrated in one structurally uniform unit made of hard plastic, the unit obtained by welding two identical injected subunits.

1 . A solar water heater comprising a container for holding water of a volume between 60 and 200 liter, and a sun light collector of a surface between 0.8 and 2 m 2 , integrated in one body essentially having a parallelepiped shape, the body comprising two connected half-units, each unit injection molded from a thermoplastic polymer, and each unit provided with a plurality of columns protruding through the internal volume of said heater, wherein each column touches a column from the other half-unit without compartmentalizing said inner volume. 
     
     
         2 . A solar water heater according to  claim 1 , said two half-units being heat welded or bonded. 
     
     
         3 . A solar water heater according to  claim 1 , said two half-units being identical or different. 
     
     
         4 . A solar water heater according to  claim 1 , essentially having the shape of a flat parallelepiped made of two plastic, injection molded, half-units, comprising rectangular upper and bottom faces, and a transparent sheet mounted on said upper face and a non-transparent sheet or insulating layer mounted on or in said bottom face. 
     
     
         5 . A solar water heater according to  claim 1 , wherein said body comprises an upper face and a bottom face of the same rectangular shape, and columns protruding from said upper face downward and columns of the same shape protruding from the bottom face upwards, the two column systems being positioned against each other, each column touching a column from the opposite wall, the double column height essentially determining the distance of said two faces, each pair of the opposite columns being tightly connected by heat welding or by bonding. 
     
     
         6 . A solar water heater according to  claim 1 , comprising no partition means for separating water absorbing the sun light from water stored for later use. 
     
     
         7 . A solar water heater according to  claim 1 , consisting essentially of three main structural components: one compact body, a transparent sheet, and a non-transparent sheet, the heater being made of plastic, except for said transparent sheet which may be made of glass. 
     
     
         8 . A solar water heater according to  claim 7 , wherein said compact body has an upper face and a bottom face and is obtained by heat welding or by bonding of two identical half-units prefabricated by injection molding, said transparent sheet mounted onto said upper face and said non-transparent sheet onto said bottom face. 
     
     
         9 . A method for manufacturing a solar water heater having a container for holding water and a sun light collector of a rectangular surface integrated in one body essentially exhibiting a parallelepiped shape, comprising
 i) injection molding a half-unit having essentially the shape of a an open flat parallelepiped having one base and lateral faces, the base and faces defining a half of the internal volume of said heater, and columns protruding from said base within the internal volume having a height approximately equal to the height of said faces;   ii) precisely apposing two half-units molded according to step i) in such a way that each column from one half-unit touches a columns from the second half-unit;   iii) joining said two half-units, without compartmentalizing the inner volume of the heater, thereby closing said internal volume in a water-proof manner, the volume serving as a tank for containing water to be heated; and   iv) mounting a transparent sheet onto one base of said tank, and a non-transparent sheet onto the other base of said tank.   
     
     
         10 . A method according to  claim 9 , wherein said two half-units are joined by heat welding or by bonding. 
     
     
         11 . A method according to  claim 9 , wherein said two half-units are identical. 
     
     
         12 . A method according to  claim 9 , wherein said heater comprises a plastic body formed by welding two identical half-units each formed by injection molding, said body having an upper face, a bottom face, and lateral faces, said upper face being depressed and said bottom face being elevated, said upper face enclosing an upper insulating air layer together with the lateral faces and said transparent sheet, and said bottom face enclosing a layer of insulating materials together with the lateral faces and said non-transparent sheet. 
     
     
         13 . A method according to  claim 9 , wherein said injection molded half-units comprise structural features enabling to functionally close the internal volume of the water tank, to mount the transparent and non-transparent sheets on the tank, and to connect the heater with pipes and desired accessories. 
     
     
         14 . A method according to  claim 9 , wherein said injection molded half-units are shaped to provide maximal mechanical strength at minimal weight. 
     
     
         15 . A method according to  claim 9 , wherein the main structural component of said sun water heater consists merely of one compact polymer body, obtained by bonding or by heat welding of two identical half-units prefabricated by injection molding of a thermoplastic polymer.