Solar Heated Hot Water System

This application claims priority from South African Patent Application 2005/06317 dated 8 August 2005, the entire contents of which are incorporated herein by reference as if 5specifically reproduced herein and it forms an integral part of the disclosure of this specification. Where the present specification is in conflict with the priority application then the present specification prevails.

Field of the Invention

The invention relates to an inexpensive and simple system for providing heated water lOby utilizing solar energy.

Background to the Invention

The inventor is aware of solar heaters for water which provide both household and industrial hot water.

These systems are expensive and typically include welded metal and glass in 15construction, are thus relatively expensive to manufacture, are cumbersome to transport and require a professional to install.

One system of which the inventor is aware is disclosed in US Patent 6,014,968 a collector core for a solar water-heating-system includes a plurality of heat-absorbing pipes each of which surrounds a cooler-water return-pipe. The heating-pipes may

20connect directly to an insulated hot-water storage-tank from which cooler water descends through the return-pipes into the heating-pipes. Upon reaching the end of the return-pipes, the cooler water flows outward into the space between the surrounding heating-pipes and the inner return-pipes. Upon warming, water between the two pipes rises upward back to the hot-water storage-tank thus completing the thermosyphon flow

25cycle. Preferably, the inner return-pipe is made of polyvinyl chloride ("PVC"), polybutelene ("PB"), or other compressible material which permits collector core operation both in freezing and non-freezing environments.

The inventor has realized that in order to provide an economically feasible solar heating system for low cost housing and low income earners such as those typically found in South Africa and other developing countries the traditional solar heating system such as that disclosed in US 6,014,968 described above should be simplified to perform the 5heating function while keeping acquisition, installation and maintenance costs to a minimum.

A further objective would be to integrate and simplify manufacturing to minimize cost and increase reliability of geyser.

A further objective would be to keep the number of parts to a minimum so that no lOadvanced technical skills are required to erect the heating system and to maintain it.

With the above in mind, the inventor proposes the following invention.

Summary of the Invention

According to a first aspect of the invention, there is provided a solar water-heating- system which includes:

15- a water storage tank having a plurality of integrally formed pipe-tails/nipples for connecting to heat absorbing pipes, and an outlet for supplying water from the water storage tank which outlet is located, in use, elevationally above the pipe- tails; and

- a plurality of heat-absorbing pipes, each of which connect directly to the water

20 storage tank from which cooler water descends into said pipes and upon solar warming, heated water rises upward back to the water storage tank thus completing the thermosyphon flow cycle resulting in the contents of the water storage tank becoming heated.

The cooler water may descend into each of the pipes and upon solar warming, heated 25water rise upwards back to the water storage tank within the same pipe in which it descended.

The water storage tank may have an inlet for water to be heated.

The outlet may be located elevationally between the inlet and the pipetails.

The heat-absorbing pipes may be closed at one end.

The system may include a secondary tank so that the heat-absorbing pipes are connected to the water storage tank at one end and to the secondary tank at the other 5end.

The inlet may be connected to the secondary tank so that the water to be heated is introduced into the system at the secondary tank and heated water is withdrawn at the outlet on the water storage tank.

Where the inlet is at an upper zone of the water storage-tank, the inlet may include a lOscrew threaded opening having a screw threaded closure member, said opening being sized and dimensioned to permit filling of the tank by bucket or the like.

The inlet may have a screw threaded closure member which engages a screw threaded mouth opening, jar-fashion.

The mouth opening may be from 50 mm to 200 mm, typically 80 mm.

15The inlet may include a pipe tail or pipe connector for connecting to a water supply.

The inlet may include both the mouth opening and the pipe tail.

The heat absorbing pipes may be made of polyethylene, PVC, polypropylene, polybutene, or the like.

The heat absorbing pipes may be from 10 mm to 80 mm in diameter.

20Typical heat absorbing pipes may be 25 to 50 mm in diameter.

The heat absorbing pipes may be from 500 mm in length, however, the limit on the length is only a practical one.

Typical heat absorbing pipes may be from 800mm to 1750 mm in length.

The heat absorbing pipe may be articulated.

The water storage tank may be from 40 to 500 litres in volume, typically from 50 to 200 litres .

A typical size presently envisaged is 105 litres within the tank itself and 20 liters are held withing the pipes resulting in a capacity of 125 liters.

5A float valve, such as that used in toilet cisterns, may be located in the water storage tank, an inlet portion of the float valve assembly being directed to the outside of the water storage tank for connection to a water supply and an outlet portion of the float valve being directed into the bottom of the interior of the water storage tank, whereby when a water supply is connected to the float valve the level of water in the water lOstorage tank may be maintained with the cold water filling from the bottom pushing the warmer water upwards towards the outlet which is near the top of the tank.

The water storage tank has a substantially flat based configured to be supported by a roof panel of a structure or b a frame supported on said structure.

The water storage tank and mouth opening of the inlet may be dimensioned to permit 15for storage of the heat absorbing pipes in the tank for sales and transportation purposes.

Thus, the diagonal length of the interior of the water storage tank from the inlet to an opposing inner wall may exceed the length of the heat absorbing pipes to be stored therein.

20If the length of the tank is not sufficient to store the pipes at full length then the pipes may be cut in pieces so they fit into the tank and articulated/joined once reaching the site of installation.

The water storage tank may be rotationally moulded from a plastics material with the nipples/pipe-tails for the heating pipes integrated into the tank .

25The water storage tank may be made from polyethylene, polypropylene, polybutene, PVC ₁ ABS, or any other suitable material.

The system may include a bracket for installation of the water storage tank onto a roof of a structure in which the heated water is to be utilized.

The bracket may include a hook portion which hooks onto an apex portion of the roof. In use, the water storage tank may be supported on the bracket with the heat absorbing pipes protruding away and downwardly from the tank.

The hook may include a spiral portion which assists in retaining the bracket on the roof 5and is in contact with the roof so that a curved portion of the bracket is in contact with the roof.

The bracket may be inserted into the water storage tank for transportation, similarly to the heat absorbing pipes as described above.

The bracket may be made from mild steel, however, the bracket may be made of wood lOor even plastics material.

The heat absorbing pipes may have a central zone which is off-round so that, in use, a larger surface area of the heat absorbing pipe may face upwards than if the heat absorbing pipes were round.

The system may include insulating the water storage tank.

15lnsulating the water storage tank may entail insulating at least a portion thereof with mineral wool. One brand of such mineral wool is Pink Aerolite™ .

The water storage tank may have a portion insulated with polystyrene.

In one embodiment, the water storage tank is blanketed in mineral wool over the extent of its arcuate surface and the blanketed water storage tank is retained within a housing.

20In another embodiment, the blanketed water storage tank has polystyrene positioned adjacent its flat surface and a cover is positioned over the opening to the housing thereby enclosing the water storage tank in an insulated enclosure.

A single embodiment may include both of the above embodiments.

In yet a further embodiment, bubble plastic or another translucent plastics material 25having air bubbles trapped therein, such as Aerothene™ may be wrapped around the tank and the installed heat absorbing pipes thereby to permit sunlight to penetrate through to the heat absorbing pipes while reducing heat loss therefrom.

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In yet a further emobodiment the heating pipes could be surrounded by translucent plastic film allowing sunlight to penetrate and minimizing heat loss by stagnating the air around the pipes.

In yet a further embodiment, the system may have a reflective surface behind the pipes 5that will reflect sunlight falling betweent the pipes onto the sides and the backs of the pipes increasing the rate of heating and the heated water temperature achieved. This will especially optimise heating when the sun is at an angle and not at it's strongest.

The invention extends to a method of installing a solar hot water heating system having a water storage tank which has an inlet coupled to a float valve designed to maintain the lOwater level in the water storage tank and an outlet, which system is located on the roof of a structure in which hot water produced thereby is to be used, said method including:

- coupling a supply hose connected to a water supply to the inlet of the water storage tank; and

- coupling a consumption to the outlet of the water storage tank and leading the 15 hose pipe into the structure to a point where warm water is required.

The supply hose may be a garden hosepipe.

The consumption hose may be a garden hosepipe.

The objective of using a hosepipe installation and not connecting the way a conventional, solar water heater would be is to minimise costs, make installation by a 20novice possible and make installation quick and easy.

The method extends to providing the consumption garden hose pipe with a throttle valve arrangement proximal the consumption end thereof where the water is used without the need for a valve directly on the outlet of the water storage tank.

The method extends to mounting the water storage tank on the roof of the structure by 25supporting said tank on a bracket or cradle which hangs from the apex of the roof by hooks. This does away with the need for removing roof tiles and/or drilling into the roof.

This method also extends to using two or more L shaped brackets, drilling holes into the roof and mounting the brackets which would stop the geyser from sliding down the roof.

The invention extends further to a method of providing hot water to a consumer in a structure not having access to running water, said method comprising:

- filling a water storage tank of a solar water heating system with a bucket through a mouth opening of the tank;

5 - coupling a consumption hose pipe to an outlet of the water storage tank and leading the hose pipe into the structure to a point where warm water is required.

The mouth opening may be 50mm in diameter.

The mouth opening may be screw threaded, however, the mouth opening may be configured to receive a cap closure member.

lOThe outlet may be in a bottom portion of the water storage tank.

The hose pipe may be provided with a throttle valve at its consumer end.

The invention extends to a bracket for mounting a solar water-heating system to a roof, said bracket including a hook portion which makes contact with a portion of the roof over the apex of the roof from a water-storage tank of the system.

15The bracket may have a free end of the hook having a curled portion configured to make contact with the roof.

The invention extends to a system such as that described above, wherein the tank, the housing, or both, are coloured in the colours of a sponsor.

A logo or name of a sponsor may be applied to any portion of the system, typically the 20water storage tank.

Thus, the roof of a dwelling of a user becomes advertising space for a sponsor.

The tank, the housing, or both, may be used as a bill board for displaying advetising material of a sponsor.

Description of Embodiments of the Invention

25The invention will now be described, by way of non-limiting example, with reference to the accompanying diagrammatic drawings and figures in which:

Figure 1 shows, in three dimensional view, a water storage tank of a solar water heater;

Figure 2 shows and exploded view of the tank of Figure 1 with heat absorbing pipes and a closure cap;

Figure 3 shows, the tank of Figure 2 with the pipes connected;

5Figure 4 shows, the tank of Figure 3 fitted to a roof of a dwelling;

Figure 5 shows, the tank of the invention on a bracket with a cover and insulation;

Figure 6 shows detail of the mounting bracket for mounting the solar water heater to the dwelling;

Figure 7 is a graphical representation of the heating of water by an uninsulated solar lOwater heater on a typical summer days in Pretoria, South Africa; and

Figure 8 is a graphical representation of the heating of water by an uninsulated solar water heater on typical winter days in Pretoria, South Africa.

In Figures 1 to 6, reference numeral 10 broadly indicates a solar water heater generally in accordance with the invention.

15The heater 10 has a water storage tank 12 having a screw threaded inlet opening 14 and pipe tails 16 to which heat absorbing pipes 18 can be attached and an outlet pipe tail 20 to which a consumer garden hose pipe 22 can be connected for supplying heated water to a user.

The hose pipe 22 may be a 20 mm green hosepipe, such as that available under the 20trade mark Gardena™ which is provided with hose pipe fittings of the same brand. A twist-to-close hose accessory made by Gardena™ or a similar device may be used to regulate the flow of heated-water at the consumption end of the hose pipe 22.

The tank 12 and pipe tails 16 are integrally formed by rotational moulding from a plastics material such a polyethylene.

25The opening 14 is sized to permit the tank 12 of the example to be filled by bucket, but also for the pipes 18 to be inserted into and removed from the tank 12 for sales, transport and assembly purposes. The opening 14 is closeable by a screw cap 15.

In the example of the Figures, the screw threaded opening 14 is an 80 mm opening.

The pipes 18 connect directly to the hose tails 16 and hose clamps 24 may be used to secure the pipes 18 onto the hose tails 16.

Plugs are inserted into the open ends 26 of the pipes 18 thereby to seal the pipes 18 at 5their free ends.

In use, when the tank 12 is filled with water, the cooler water descends into the pipes 18 and upon solar warming, heated water rises upward back to the water storage tank 12 thus completing the thermosyphon flow cycle resulting in the contents of the water storage tank 12 becoming heated. The heated water can then be drawn from the tank 1012 by gravity through outlet 20 and hose pipe 22 to the point of use.

In the example, the pipes 18 are made of black polyethylene and have a nominal diameter of 32 mm. The pipes are 1500mm in length (cut in half into 750mm lengths for transport and joined together for installation) and 16 pipes are used for a 120 litre volume solar water heater. The length of the pipes 18, their diameter, and the number 15of pipes is a function of expected environmental conditions and required heating.

In an embodiment not shown in the Figures, a float valve, such as that used in toilet cisterns, may be located in the water storage tank, an inlet portion of the float valve assembly being directed to the outside of the water storage tank for connection to a water supply and an outlet portion of the float valve being directed into the bottom of the 20interior of the water storage tank, whereby when a water supply is connected to the float valve the level of water in the water storage tank may be maintained with the cold water filling from the bottom pushing the warmer water upwards towards the outlet which is near the top of the tank.

The heater 10 includes a bracket 28 for installation of the tank 12 onto a roof 30 of a 25dwelling structure 32 in which the heated water is to be utilized.

The bracket 28 includes a hook portion 34 which hooks onto an apex portion 36 of the roof 30. In use, the water storage tank 12 is supported on the bracket 28 with the heat absorbing pipes 18 protruding away and downwardly from the tank 12, as shown in the Figures.

The bracket has curled portions 29, each of which provide a contact point 31 with the roof 31 to retain the bracket 28 and the tank 12 in situ on the roof. An apex portion 27 of the bracket 28, together with said curled portions 29, as shown, make the bracket 28 suitable for a wide variety of roof copnfigurations.

5The bracket 28 may be inserted into the water storage tank 12 through the opening 14 for transportation, similarly to the heat absorbing pipes 18 as described above and be assembled upon arrival at final destination.

The bracket 28 may be made from mild steel.

As shown in Figure 5 the heater 10 may include insulation for the water storage tank 12.

lOlnsulating the water storage tank 10 may entail insulating at least a portion thereof with mineral wool 11. One brand of such mineral wool is Pink Aerolite™ .

The water storage tank may have a portion insulated with polystyrene 13.

In one embodiment, the water storage tank is blanketed in mineral wool over the extent of its arcuate surface and the blanketed water storage tank is retained within a housing 1519.

In another embodiment, the blanketed water storage tank has polystyrene positioned adjacent its flat surface and a cover is applied to the housing thereby enclosing the water storage tank in an insulated enclosure.

A single embodiment may include both of the above embodiments.

20In yet a further embodiment, bubble plastic or another translucent plastics material having air bubbles trapped therein, such as Aerothene™ may be wrapped around the tank and the installed heat absorbing pipes thereby to permit sunlight to penetrate through to the heat absorbing pipes while reducing heat loss therefrom.

In yet a further emobodiment the heating pipes could be surrounded by translucent 25plastic film allowing sunlight to penetrate and minimizing heat loss by stagnating warm air around the pipes.

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n yet a urt er em o men , t e system may ave a re ect ve sur ace beh nd the pipes that will reflect sunlight falling betweent the pipes onto the sides and the backs of the pipes increasing the rate of heating and the heated water temperature achieved. This will especially optimise heating when the sun is at an angle and not at it's strongest.

5 Experimental Data

Several tests were conducted to determine the efficacy of the heater 10. The results of these tests are tabulated in Tables 1 and 2 below and also shown graphically in Figures 7 and 8. In short, acceptably high water temperatures could be obtained even in winter when ambient temperatures and inlet water temperatures are low and conditions for lυsolar heating, including the angle of the sun, unfavourable.

Table 1 : Typical Summer Results with Uninsulated Tank

Table 2: Typical Winter Results with uninsulated tank