[0002] Many types of solar heaters have been proposed. Generally the heaters are of sophisticated construction and, accordingly, are expensive. In a developing country the need for hot water is as acute as in a developed society. However the high price which is associated with traditional solar heaters means that the benefit of hot water, derived from solar heating, is a luxury beyond the reach of most potential users.

[0003] An object of the present invention is to provide a solar heater assembly which can be constructed from low cost and readily available components.

SUMMARY OF THE INVENTION

[0004] The invention provides in the first instance a closure for use in a solar heater assembly which includes a body which is sealingly engageable with a mouth of a container, at least a first port through the body which allows a medium to flow through the body from the container and at least a second port through the body which allows a medium to flow through the body into the container.

[0005] Depending on the application the medium through the first port may be water or air and the medium through the second port may be water or air.

[0006] Each port may include a respective tubular section and at least one retention formation on an inner surface of the tubular section which is frictionally and sealingly engageable with a tube of appropriate dimensions which is inserted into the tubular section.

[0007] The closure may include a plurality of the first ports.

[0008] The invention also provides a water heating vessel for use in a solar heater assembly which includes a container with a mouth, a closure of the aforementioned kind which is engaged with the mouth, a first tube which is engaged with the first port and which extends into the container, and a second tube which is engaged with the second port. A greater part of the second tube may be located outside the container.

[0009] The invention further provides a water supply vessel for use in a solar heater assembly which includes a first container with a mouth, a closure of the aforementioned kind engaged with the mouth, a first tube engaged with the second port which extends into the first container and which, in use, allows air to flow into the first container, and a second tube engaged with the first port which allows water to flow from the first container.

[0010] The aforementioned components can be used to construct a solar heater assembly which includes the water supply vessel which is positioned so that the mouth of the first container is lowermost and at least one water heating vessel of the aforementioned kind which is positioned at a lower elevation than the water supply vessel and which is supplied with water from the first container.

[0011] A tube used to draw water from the container of the water heating vessel may include a valve of any appropriate form, for example a pinch valve, which is used to compress the tube closed thereby to achieve controlled water flow from the second container. [0012] Each tube may be flexible.

[0013] A plurality of the water heating vessels may be employed. These may be positioned so that they are successively lower, in elevation. Thus water from the supply vessel can flow sequentially through the water heating vessels under gravity action.

[0014] However, if water pressure (e.g. from a pressurised water supply) is used to cause water flow through the vessels, then the vessels may be positioned in desired and suitable elevations e.g. in line with one another.

[0015] The water heating vessels may be blackened or be placed on a dark background to provide an enhanced solar radiation absorption capability.

[0016] The vessels may be housed in an insulated housing which has a light transmissive cover, e.g. of glass.

[0017] The invention further extends to a solar heater assembly which includes a water supply vessel and a plurality of water heating vessels which are exposed to solar radiation and which are arranged in a serial array wherein the vessels are progressively lower in elevation so that water from the water supply vessel is fed by gravity action in succession through the water heating vessels.

[0018] In order to lower the cost of the solar heater assembly the water heating vessels are preferably containers used for commercially available products such as carbonated soft drinks. In practice these containers, once used, are often discarded. It is possible though, through the use of a plurality of closures, each of the aforementioned kind, to interconnect a number of the containers which then function as solar collectors. Each water supply vessel should have a volume of adequate size to ensure that sufficient water is available, from an interconnected plurality of the vessels, for a reasonable period of usage before replenishment is called for.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention is further described by way of example with reference to the accompanying drawings in which:

Figure 1 and Figure 2 are plan and cross-sectional views respectively of a first closure according to the invention;

Figures 3 and 4 are plan and cross-sectional views respectively of a second closure according to the invention which, although differing in appearance to the first closure, is based on similar inventive principles; and

Figure 5 illustrates a solar heater assembly according to the invention. DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] Figures 1 and 2 of the accompanying drawings illustrate a first closure 10 in plan and cross-section respectively, according to the invention. The closure includes a body 12 which is moulded from a suitable plastics material. The body has a section 14 which carries internal threads 16 which are sized to engage sealingly with a mouth of a suitable container. A washer, not shown, can be used to enhance the sealing action.

[0021] A centrally positioned inlet port 20 is located on a surface 22 of the body. This port is surrounded, in this example, by four exit ports 26. The exit ports are identical to each other and to the inlet port. [0022] Each port includes a respective tubular section 30 with a toothed retention formation 32 which extends circumferentially on an inner surface of the tubular section. The design is such that an end 34 of an appropriately dimensioned flexible plastic tube 36 (see Figure 2) can be inserted into the tubular section. When the tube is passed through the retention formation it is deformed slightly and in this way it is effectively sealingly engaged with the tubular section.

[0023] The closure 10 is intended to be used with a container which is inexpensive and which acts as a water supply vessel. A number of containers, suitably interconnected, could be used or a single, relatively large container, with a larger closure, could be employed.

[0024] Figures 3 and 4 are plan and cross-sectional views respectively of a second closure 40 according to the invention. In principle the closure 40 is the same as the closure 10 although constructional details differ. The closure 40 has a body 42 with a cup-shaped section 44 which carries internal threads 46 which can be engaged in a sealing manner with a mouth of a carbonated soft drink container, not shown which, typically, is made from PTFE.

[0025] Two ports 48 and 50 are positioned on a surface 52 of the body. The ports are substantially identical to each other and each port includes a tubular section 54 with an internally positioned retention formation 56 which has similar properties to the retention formation 32 shown in Figure 2. Thus an end 58 of a flexible plastic pipe 60 of suitable dimensions (see Figure 4) can be inserted directly into the bore of the tubular section and can thereby be engaged in a sealing manner with the retention formation. [0026] Figure 5 illustrates a solar heater assembly 70 according to the invention. This includes a water supply vessel 72 and a number of water heating vessels 74A,

74B, 74N which are interconnected in a serial fashion. The water heating vessels are identical, and the number of vessels can be varied. [0027] The water supply vessel 72 may have a capacity of 20 to 50 litres (by way of example only). The vessel has a threaded mouth 76 and engaged therewith is a first closure 10 of the kind shown in Figures 1 and 2. A tube 78 is engaged with the port 20 and extends into an interior 80 of the vessel to what, usually, is a base 82. A tube 84, which preferably is flexible, is engaged with one of the ports 26 and extends to a first water supply vessel 74A.

[0028] The remaining ports 26 on the closure 10 can similarly be connected to respective arrays of water heating vessels, not shown. Alternatively, according to requirement, the remaining ports which are not utilised in this way are simply sealed.

[0029] The water heating vessel 74A includes a container 88 which, preferably for cost reasons, is a discarded container of the kind typically used for carbonated soft drinks. A mouth 90 of the container is engaged with a second closure 40 of the kind shown in Figures 3 and 4. An end of the tube 84 is engaged with one of the ports 48 and 50. A second tube 92 is engaged with the other port. The tube 92 is positioned so that a portion 92A thereof extends into an interior of the container 88. A second portion 92B of the tube 92 is looped and is engaged with another second closure 40 which, in turn, is engaged with a second container 88, of the kind described, to make up the second water heating vessel 74B.

[0030] The process is continued in this way with the capacity of the solar heater system being limited only by the number of containers 88 which are included in the array. As the various closures 40 and the interconnecting tubes are low cost items, and as the containers 88, invariably, have no significant value it is possible to configure a substantial array of water heating vessels with little expenditure. The containers are thus serially interconnected to one another with an outlet tube of an upstream container connected to, or serving as, an inlet tube of a following, downstream container.

[0031] To improve the solar absorption capabilities of the array the individual containers 88 can be coated with black paint or they can be covered with black plastic sheeting. Alternatively the containers can be placed on a black background. These aspects, although desirable, are not essential.

[0032] Additionally, the containers can be placed in a thermally insulated housing indicated by a dotted line 94, to which is fitted a light transmissive cover 94A. This type of arrangement helps to reduce thermal losses from the containers.

[0033] A final container 88N has a discharge tube 96 which carries a valve 98 which is used to close or open the tube to control water flow through the tube. The valve 98 is a low cost device and works with a screw action to compress the tube closed. The screw is released to allow the tube to open and so permit water flow through the tube.

[0034] In use of the assembly shown in Figure 5 the water supply vessel 72 is filled with water and the closure 10 is engaged with the mouth 76. The vessel is then placed at an elevated position and inverted. Thereafter the array of water heating vessels 74A to 74N is connected to the closure 10 in the manner illustrated. The individual containers 88, preferably in an insulated container, of the kind described, are exposed to solar radiation. The water in each container is thus heated. A conventional thermo-siphon action cannot take place however because there is no closed loop in the assembly. Water flow can thus take place in one direction only through the assembly.

[0035] When hot water is desired the valve 98 is opened. Water then flows from the lowermost container 88N under gravity action. In the process water is displaced from each of the upstream containers with replenishment, in each container, taking place with water flow from the preceding container 88 and, ultimately, from the vessel 72. With this arrangement it is only due to gravity action that water flow takes place.

[0036] Initially the temperature of the water in each container is substantially the same. When water is drawn from the system though the uppermost container is filled with cool water for its hot water content is displaced to an adjacent lower container. The cool water only enters the lower containers when their hot water contents are dispensed. This feature allows a maximum quantity of hot water to be drawn from the system and avoids a disadvantage which is associated with some solar heater systems, namely that hot water, drawn from a storage vessel, is replenished with cold water which is then mixed with the remaining hot water thereby dropping the temperature of the stored water. In the assembly of the invention the hot water is kept in a number of relatively small containers which are separated from one another. Thus, temperature reduction effectively only takes place, in the stored water, if the warm contents of all of the containers 88 are depleted in a relatively short time.

[0037] The tube 78 allows air to enter the container 70 to replace water which is drawn from the container. [0038] The tube portion 92A extends into the interior of the container 88 to ensure that the water content of the container is displaced by the incoming cold water in a way which reduces mixing of the cold water with the hot water. A similar effect is achieved in each of the succeeding water heating vessels for, at least initially, hot water flows into a vessel and displaces hot water.

[0039] A benefit of the invention lies in the fact that an effective solar heater assembly can be made from containers 88 which, typically, would otherwise be discarded, a number of the closures 40, a closure 10, the water supply vessel 72 and lengths of flexible tubing. The vessel 72, via the plurality of exit ports 26 which are provided in the closure 10, can be used to supply in parallel, different arrays of water heating vessels.

[0040] The containers 88 would normally be PTFE or similar soft drink containers. Such containers do degrade due to the effects of sunlight. The use of glass bottles in place of plastic containers avoids this aspect.

[0041] The vessel 72 is elevated to provide a pressurized water source. If pressurized water is available from a different source, e.g. a main supply, then the tube 84 can be directly connected to the main supply and the vessel 72 would not be required.