GB2455578A - Solar water heater - Google Patents

Abstract

An integrated solar water heater comprises an elongated tubular collector 7, for absorbing solar radiation, having headstock and tailstock 11 end cap assemblies securely located at each end of the collector respectively. The water heater includes an elongated tubular insulator 2 which forms a water storage tank 12 within it, respective to the collector shape. The insulator provides a means for convectional water flow (thermosiphonic flow) between an interstitial space 8 positioned between the outer surface of the insulator and the inner wall surface of the collector. Preferably, a series of water channels 5 are located within each end of the storage tank insulator, the water channels being inclined upwards obliquely. The insulator may be supported and stabilized by bridges situated against the inner surface wall of the collector. Preferably, the end cap assemblies secure and seal a concentric outer cover 9 around the collector, where the cover is transparent to solar radiation. A connection may be provided on the tailstock end cap for receiving an electric immersion heater. An air pocket may be formed in the water storage tank to be used as a pressure regulator against internal water expansion. Preferably, a non-return valve 6 is fitted over the channels inside the water storage tank to prevent reverse cycling of the system at night.

Description

1 2455578

SUMMERY OF THE INVENTION

Most conventional forms of solar water heaters have as a point for receiving solar radiation through a collector panel, which contains the medium for converting solar radiation via a heat exchange mechanism. Generally, the collector panel comprises of a series of pipes connected to an absorber where water from the storage tank is circulated into the collector through the action of thermo siphon or forced flow via a pump, and recently the innovation of the heat pipe is being utilized for extra efficiencies. Heat pipes may be used in conjunction with a manifold where the hot water is then pumped to a storage vessel, or an array may be directly connected to the tank.

From the aspect of fabrication, solar water heaters are generally labour intensive to manufacture, many parts are involved in the construction, Items made from metal and glass add to the cost dramatically. This is then reflected in the cost to benefit ratio.

Moreover, the design criteria for systems that operate in tropical climates are different to that of the requirements for such systems that operate in temperate conditions. In tropical and sub tropical climes where most of the developing nations are situated, the ambient water temperature closely follows that of air temperatures. Because of the reduced amount of solar radiation in the temperate climates, solar water heaters in these situations have design characteristics to allow for optimum performance extracting whatever the limited amount of prevailing solar radiation. The factors that govern these systems tend to override the benefits they would have in an environmental setting such as in developing lands simply because of inherent cost constraints that are accommodating technology that is inappropriate to its usage.

Appropriate technology for developing countries requires that such systems are just that, and so suitably adjusted around their own climatic conditions.

With the worlds focus on renewable energy, it is important that such technology can be made available whereby cost constraints do not impede any supposed cost to benefit ratio.

What is ideally required is a method whereby the benefits of employing such renewable technologies have a beneficial impact on an immediate scale where such cost to benefit ratio is the prime concern.

Given these considerations, it is therefore the purpose of the present invention to address these problems.

It is also envisaged that tooling particularly for the ends caps and the insulator, pipe extrusion for the tube, are all justified based on large scale economies.

There are three embodiments to the present invention. Although this invention primarily concerns itself with the application of suitable technology for developing countries, very simple stage modifications mean the system can perform reasonably well in tropical as well as temperate climates.

The system is an integrated solar water heater, which has essentially just six parts comprising the first embodiment. This is achieved by employing a tube preferably made from a black CPVC [chlorinated poiy vinyl chloride] polymer, and comprises a head and a tail stock end cap assembly made from the same material, and a molded polystyrene insulating liner. A configuration whereby both solar collector and storage tank share a common assembly within the tube along with all necessary workings provide this system a very simplistic layout.

Although not possessing the thermal conductive properties as metals, plastics will conduct heat energy; unlike metals where electrons are free to move about which ensures a rapid response in conduction. It is generally thought that plastics rely on inter atomic bombardment called phonons, as radiation falls on a plastic surface the kinetic energy of molecules vibrating and colliding produce heat.

All thermo siphon solar water heaters operate on the same principle of water cycling within a closed circuit, as heat is applied wanner water becomes less dense and subsequently rises. Colder water being denser replaces the warmer water. The principle of this type of cycling is caused by convectional currents within the body of water.

The present invention uses this principle of operation very effectively, as only a thin layer of water is subject to the heating process at any one time.

Absorption of heat from the collector is almost proportional to the surface area of water that is allowed to be exposed to it. Since this spreading out of water has a ratio of almost one to one to the collector area, this boundary of heat exchange maximizes the transference of energy. This extra efficiency offsets the fact that a polymer is utilized to conduct the heat.

Convectional currents are set up at the interstitial space between the inner wall of the collector and the insulator, and deposit the hot water into a storage tank formed from the insulator.

The hot water take off point extends into the storage tank some distance; this provides an air buffer zone in that as water is heated, expansion takes place as the pressure rises; water is forced into the air buffer zone this then acts as a pressure relief mechanism. The containment of water pressure is a passive way of controlling internal pressure and allows the water bubbles that form when heated to collect and be discharged internally, rather than the employment of an external vent valve.

The unit employs two connections, the input side is fed from the bottom tail stock cap connection into a water diffuser, and take of water is from the head stock cap, here a pressure relief valve can be fitted to the circuit.

A back up electric heater can be optionally fitted for occasions where there is insufficient solar radiation. This is installed next to the cold-water intake.

Advantages of the invention: [1] The invention has three embodiments; the first embodiment of the system is essentially intended for operational use in areas of the world with a high solar gain. In the second embodiment, the system performs more efficiently at absorbing solar energy by the addition of an outer transmission cover, which traps more of the heat radiated. The third embodiment, which increases the thermal performance even further, is achieved by evacuating the air between the transmission cover and collector.

[2] Low cost to benefit ratio, free solar energy can only be ascertained on Break even costmgs. Obviously, a system can only be cost effective if the returns are based on a short-term pay back. Long term forecasts over projected break-even costings works against the economic concept of free energy.

[3] A low weight and a one piece integrated unit makes installation easier.

As solar water heaters are generally installed on rooftops, it becomes expedient to have lighter loads and shorter installation times.

[4] Reliability, virtually a one-piece construction that encapsulates the few component parts, the combination collector and storage tank make the system more dependable.

[5] Possess the ability to track the sun, depending on the suns angle of orientation. The curvature of the tube can allow more of the suns rays to be perpendicular to the collector, so the angle of incident is reduced which ensures more solar radiation is absorbed.

[6] Water stratifies better due to longitudinal design, It is always more efficient to store water in a vertical column this is because as water heats up it forms various densities, in a vertical column of water each layer will have less surface area contact than if the water was contained horizontally. This becomes important because as infihl water that will be generally cold, will dilute less of the various densities allowing the stored water to be drawn off more efficiently.

[7] The unit can be pressurized to withstand common domestic water pressures depending on wall thickness of the tube used. A simple water regulator can be affixed to reduce pressure and subsequent reduction of water usage.

[8]Composed from 100% polymers so no corrosion, all the component parts comprised from inert plastic, which is unaffected by salts, electrolysis, hard or contaminated water.

[9] Modular, system demand will be dependant on capacity. Making the system modular over comes the problems of sizing. By adding in series or in parallel, it is possible to build a cascade system as one unit feeds another with a warmer grade of input water.

[10] Only two pipes are necessary for attachment to the unit, connections to the heater are a simple cold input and a hot take off, increasing reliability and cutting down installation time.

DESCRiPTiON OF THE INVENTiON

THE TUBE: In the basic embodiment of the present invention, a solar water heater is composed from a tubular pipe [7] this has the suitable characteristics to accommodate both the storage tank and form the collector as one single entity. Essentially all the component parts are located in and on a Black CPVC pipe. Chlorinated poly vinyl chloride has physical properties that allow elevated temperatures beyond normal PVC, which exhibits high heat distortion temperatures, and performs well up to temperatures of 90 degrees centigrade in pressurized systems. Since operational temperatures of this solar water heater will heat water at temperatures up to 55 degrees centigrade. This will be well within the scope of the properties of the polymer.

THE 1NSIJLATOR: The insulator liner, which is composed from molded polystyrene, has a two-fold purpose, first to provide the necessary thermal insulation for the stored water and allow the convectional currents to be generated in the small interstitial gap that is provided all way around the circumference between the outer layer of the insulator and the inner wall of the tube.

The top end of the insulator has a thicker cross sectional area than its corresponding bottom end this is because heat will always rise so a greater proportion of insulation is required.

As the bottom end contains a water disperser [1] made from sponge like polymer to disperse the in coming cold water, and this held in place by projections molded into the insulator [not shown] The insulator is preferably molded from two sections that inter-fit with each other [2] and has cut out sections to accommodate the cold intake [3] and the hot out take water [4] Along the length of the insulator are sections which have a built up area, shown in diagram 2 these provide a bridge so that the insulation fits securely against the inner face of the tube, these are ribbed in a fashion to allow the convectional currents that form in the interstitial space [8] to flow through these sections. A series of conduits, which communicate water flow between the storage tank and the collector, are located at both ends of the insulator [5] these conduits have a plane angled upwards and this is to assist flow. The bottom conduits are located after the water diffuser and disallow water to enter the collector if an amount of hot water is drawn off. Normally in a conventional thermo siphon system water would also flow into the collector, these conduits are against the in-flow of replacement water but aid and assist the convectional currents that deposit the hot water into the storage tank [12] To prevent reverse cycling of the system at night where the cooler air may incite the water to reverse flow thus cooling the stored water down, a plastic film [6] is positioned over the conduits, which allow the hot convectional currents to flow into the storage tank, but acts as a non-return valve blocking reverse cycling.

THE COLLECTOR: The collector is the thermal solar absorber, and in diagram [2] illustrates the Incoming solar radiation [a] falls directly onto the collector [b] as the collector starts to heat up a proportion of this energy [c] is directly absorbed by the collector and then re-emitted back to the transmission cover [d] whereupon subsequent absorption and re-emittance takes place. The incoming radiation falls as short wave Infrared and the subsequent re-ennttance radiates in long wave infrared, as the transmission cover is opaque to the radiation the collector starts to heat up.

Heat is transmitted through the collector by conduction and absorbed by the water contamed in the interstitial space [e] it then fonns convectional currents [f] which rise through the insulator bridges [g] which stabilize the insulator {hJ At such a time of usage and particularly at night this becomes important because the interstitial space has a layer of still water which acts like the insulation of a divers wet suit. In a divers wet suit the wearer heats up this thin layer of water until a uniform feeling of comfort exists.

In the present invention, this interstitial water adds to the thermal performance when the system is not under solar radiation.

HEAD AND TAIL END STOCK CAPS: Both the collector tube and the transmission cover fit into a headstock cap assembly and a corresponding tail end stock cap [ii]. These caps are preferably made by injection molding and composed from the same CPVC material as the tube.

Both end caps are engineered with spigot recesses, which accommodate the tube. If the outer transmission cover is required then it is assembled at the same time as the tube The outer concentric groove that accommodates the transmission cover is sealed and bonded to the end cap by a flexible sealant, this is to accommodate the different coefficient of expansion between the transmission cover and end cap. The tube is pressed into the end cap and is mechanically and chemically bonded permanently using a propriety CPVC cement around the outer edge of the tube and outer edge of the spigot recess.

Both end caps have threaded inserts molded in-sit-u for their respective water connections.

As it is necessary for the unit to be pressurized, the end caps have a convex shape to equilibrate pressure.

TRANSMISSION COVER: In the second embodiment of the invention, improvements in overall solar gain is achieved by the addition an outer transmission cover [9] is employed.

This cover is transparent to the incoming short wave infrared radiation, which falls on the collector surface, is absorbed and this energy is then dissipated into the fabric of the collector. As the surface of the collector starts to heat up, thermal emittance in the form of long wave infrared is re-radiated; and as the transmission cover is opaque to this long wave radiation a thermal trap is created.

Suitable materials that have the constitution to withstand the elements and that have a high degree of transmission to the near infrared radiation but block the re-radiated long wave infrared are polycarbonate, Vinyl, Glass reinforced plastics. These products can also be manufactured with the addition of suitable UV inhibitors to extend their lifespan.

In the third embodiment of the invention, the incremental step of evacuating the air space between the collector and the transmission cover [10] has the advantage of increasing the thermal efficiency even further. Evacuating the air space stops convectional air currents from cooling down the collector, and increases the insulation value even further. 1 2455578

SUMMERY OF THE INVENTION

Most conventional forms of solar water heaters have as a point for receiving solar radiation through a collector panel, which contains the medium for converting solar radiation via a heat exchange mechanism. Generally, the collector panel comprises of a series of pipes connected to an absorber where water from the storage tank is circulated into the collector through the action of thermo siphon or forced flow via a pump, and recently the innovation of the heat pipe is being utilized for extra efficiencies. Heat pipes may be used in conjunction with a manifold where the hot water is then pumped to a storage vessel, or an array may be directly connected to the tank.

From the aspect of fabrication, solar water heaters are generally labour intensive to manufacture, many parts are involved in the construction, Items made from metal and glass add to the cost dramatically. This is then reflected in the cost to benefit ratio.

Moreover, the design criteria for systems that operate in tropical climates are different to that of the requirements for such systems that operate in temperate conditions. In tropical and sub tropical climes where most of the developing nations are situated, the ambient water temperature closely follows that of air temperatures. Because of the reduced amount of solar radiation in the temperate climates, solar water heaters in these situations have design characteristics to allow for optimum performance extracting whatever the limited amount of prevailing solar radiation. The factors that govern these systems tend to override the benefits they would have in an environmental setting such as in developing lands simply because of inherent cost constraints that are accommodating technology that is inappropriate to its usage.

Appropriate technology for developing countries requires that such systems are just that, and so suitably adjusted around their own climatic conditions.

With the worlds focus on renewable energy, it is important that such technology can be made available whereby cost constraints do not impede any supposed cost to benefit ratio.

What is ideally required is a method whereby the benefits of employing such renewable technologies have a beneficial impact on an immediate scale where such cost to benefit ratio is the prime concern.

Given these considerations, it is therefore the purpose of the present invention to address these problems.

It is also envisaged that tooling particularly for the ends caps and the insulator, pipe extrusion for the tube, are all justified based on large scale economies.

There are three embodiments to the present invention. Although this invention primarily concerns itself with the application of suitable technology for developing countries, very simple stage modifications mean the system can perform reasonably well in tropical as well as temperate climates.

The system is an integrated solar water heater, which has essentially just six parts comprising the first embodiment. This is achieved by employing a tube preferably made from a black CPVC [chlorinated poiy vinyl chloride] polymer, and comprises a head and a tail stock end cap assembly made from the same material, and a molded polystyrene insulating liner. A configuration whereby both solar collector and storage tank share a common assembly within the tube along with all necessary workings provide this system a very simplistic layout.

Although not possessing the thermal conductive properties as metals, plastics will conduct heat energy; unlike metals where electrons are free to move about which ensures a rapid response in conduction. It is generally thought that plastics rely on inter atomic bombardment called phonons, as radiation falls on a plastic surface the kinetic energy of molecules vibrating and colliding produce heat.

All thermo siphon solar water heaters operate on the same principle of water cycling within a closed circuit, as heat is applied wanner water becomes less dense and subsequently rises. Colder water being denser replaces the warmer water. The principle of this type of cycling is caused by convectional currents within the body of water.

The present invention uses this principle of operation very effectively, as only a thin layer of water is subject to the heating process at any one time.

Absorption of heat from the collector is almost proportional to the surface area of water that is allowed to be exposed to it. Since this spreading out of water has a ratio of almost one to one to the collector area, this boundary of heat exchange maximizes the transference of energy. This extra efficiency offsets the fact that a polymer is utilized to conduct the heat.

Convectional currents are set up at the interstitial space between the inner wall of the collector and the insulator, and deposit the hot water into a storage tank formed from the insulator.

The hot water take off point extends into the storage tank some distance; this provides an air buffer zone in that as water is heated, expansion takes place as the pressure rises; water is forced into the air buffer zone this then acts as a pressure relief mechanism. The containment of water pressure is a passive way of controlling internal pressure and allows the water bubbles that form when heated to collect and be discharged internally, rather than the employment of an external vent valve.

The unit employs two connections, the input side is fed from the bottom tail stock cap connection into a water diffuser, and take of water is from the head stock cap, here a pressure relief valve can be fitted to the circuit.

A back up electric heater can be optionally fitted for occasions where there is insufficient solar radiation. This is installed next to the cold-water intake.

Advantages of the invention: [1] The invention has three embodiments; the first embodiment of the system is essentially intended for operational use in areas of the world with a high solar gain. In the second embodiment, the system performs more efficiently at absorbing solar energy by the addition of an outer transmission cover, which traps more of the heat radiated. The third embodiment, which increases the thermal performance even further, is achieved by evacuating the air between the transmission cover and collector.

[2] Low cost to benefit ratio, free solar energy can only be ascertained on Break even costmgs. Obviously, a system can only be cost effective if the returns are based on a short-term pay back. Long term forecasts over projected break-even costings works against the economic concept of free energy.

[3] A low weight and a one piece integrated unit makes installation easier.

As solar water heaters are generally installed on rooftops, it becomes expedient to have lighter loads and shorter installation times.

[4] Reliability, virtually a one-piece construction that encapsulates the few component parts, the combination collector and storage tank make the system more dependable.

[5] Possess the ability to track the sun, depending on the suns angle of orientation. The curvature of the tube can allow more of the suns rays to be perpendicular to the collector, so the angle of incident is reduced which ensures more solar radiation is absorbed.

[6] Water stratifies better due to longitudinal design, It is always more efficient to store water in a vertical column this is because as water heats up it forms various densities, in a vertical column of water each layer will have less surface area contact than if the water was contained horizontally. This becomes important because as infihl water that will be generally cold, will dilute less of the various densities allowing the stored water to be drawn off more efficiently.

[7] The unit can be pressurized to withstand common domestic water pressures depending on wall thickness of the tube used. A simple water regulator can be affixed to reduce pressure and subsequent reduction of water usage.

[8]Composed from 100% polymers so no corrosion, all the component parts comprised from inert plastic, which is unaffected by salts, electrolysis, hard or contaminated water.

[9] Modular, system demand will be dependant on capacity. Making the system modular over comes the problems of sizing. By adding in series or in parallel, it is possible to build a cascade system as one unit feeds another with a warmer grade of input water.

[10] Only two pipes are necessary for attachment to the unit, connections to the heater are a simple cold input and a hot take off, increasing reliability and cutting down installation time.

DESCRiPTiON OF THE INVENTiON

THE TUBE: In the basic embodiment of the present invention, a solar water heater is composed from a tubular pipe [7] this has the suitable characteristics to accommodate both the storage tank and form the collector as one single entity. Essentially all the component parts are located in and on a Black CPVC pipe. Chlorinated poly vinyl chloride has physical properties that allow elevated temperatures beyond normal PVC, which exhibits high heat distortion temperatures, and performs well up to temperatures of 90 degrees centigrade in pressurized systems. Since operational temperatures of this solar water heater will heat water at temperatures up to 55 degrees centigrade. This will be well within the scope of the properties of the polymer.

THE 1NSIJLATOR: The insulator liner, which is composed from molded polystyrene, has a two-fold purpose, first to provide the necessary thermal insulation for the stored water and allow the convectional currents to be generated in the small interstitial gap that is provided all way around the circumference between the outer layer of the insulator and the inner wall of the tube.

The top end of the insulator has a thicker cross sectional area than its corresponding bottom end this is because heat will always rise so a greater proportion of insulation is required.

As the bottom end contains a water disperser [1] made from sponge like polymer to disperse the in coming cold water, and this held in place by projections molded into the insulator [not shown] The insulator is preferably molded from two sections that inter-fit with each other [2] and has cut out sections to accommodate the cold intake [3] and the hot out take water [4] Along the length of the insulator are sections which have a built up area, shown in diagram 2 these provide a bridge so that the insulation fits securely against the inner face of the tube, these are ribbed in a fashion to allow the convectional currents that form in the interstitial space [8] to flow through these sections. A series of conduits, which communicate water flow between the storage tank and the collector, are located at both ends of the insulator [5] these conduits have a plane angled upwards and this is to assist flow. The bottom conduits are located after the water diffuser and disallow water to enter the collector if an amount of hot water is drawn off. Normally in a conventional thermo siphon system water would also flow into the collector, these conduits are against the in-flow of replacement water but aid and assist the convectional currents that deposit the hot water into the storage tank [12] To prevent reverse cycling of the system at night where the cooler air may incite the water to reverse flow thus cooling the stored water down, a plastic film [6] is positioned over the conduits, which allow the hot convectional currents to flow into the storage tank, but acts as a non-return valve blocking reverse cycling.

THE COLLECTOR: The collector is the thermal solar absorber, and in diagram [2] illustrates the Incoming solar radiation [a] falls directly onto the collector [b] as the collector starts to heat up a proportion of this energy [c] is directly absorbed by the collector and then re-emitted back to the transmission cover [d] whereupon subsequent absorption and re-emittance takes place. The incoming radiation falls as short wave Infrared and the subsequent re-ennttance radiates in long wave infrared, as the transmission cover is opaque to the radiation the collector starts to heat up.

Heat is transmitted through the collector by conduction and absorbed by the water contamed in the interstitial space [e] it then fonns convectional currents [f] which rise through the insulator bridges [g] which stabilize the insulator {hJ At such a time of usage and particularly at night this becomes important because the interstitial space has a layer of still water which acts like the insulation of a divers wet suit. In a divers wet suit the wearer heats up this thin layer of water until a uniform feeling of comfort exists.

In the present invention, this interstitial water adds to the thermal performance when the system is not under solar radiation.

HEAD AND TAIL END STOCK CAPS: Both the collector tube and the transmission cover fit into a headstock cap assembly and a corresponding tail end stock cap [ii]. These caps are preferably made by injection molding and composed from the same CPVC material as the tube.

Both end caps are engineered with spigot recesses, which accommodate the tube. If the outer transmission cover is required then it is assembled at the same time as the tube The outer concentric groove that accommodates the transmission cover is sealed and bonded to the end cap by a flexible sealant, this is to accommodate the different coefficient of expansion between the transmission cover and end cap. The tube is pressed into the end cap and is mechanically and chemically bonded permanently using a propriety CPVC cement around the outer edge of the tube and outer edge of the spigot recess.

Both end caps have threaded inserts molded in-sit-u for their respective water connections.

As it is necessary for the unit to be pressurized, the end caps have a convex shape to equilibrate pressure.

TRANSMISSION COVER: In the second embodiment of the invention, improvements in overall solar gain is achieved by the addition an outer transmission cover [9] is employed.

This cover is transparent to the incoming short wave infrared radiation, which falls on the collector surface, is absorbed and this energy is then dissipated into the fabric of the collector. As the surface of the collector starts to heat up, thermal emittance in the form of long wave infrared is re-radiated; and as the transmission cover is opaque to this long wave radiation a thermal trap is created.

Suitable materials that have the constitution to withstand the elements and that have a high degree of transmission to the near infrared radiation but block the re-radiated long wave infrared are polycarbonate, Vinyl, Glass reinforced plastics. These products can also be manufactured with the addition of suitable UV inhibitors to extend their lifespan.

In the third embodiment of the invention, the incremental step of evacuating the air space between the collector and the transmission cover [10] has the advantage of increasing the thermal efficiency even further. Evacuating the air space stops convectional air currents from cooling down the collector, and increases the insulation value even further.

Claims (1)

1. CLAIMES

   [1] An integrated solar water heater comprising an elongated tubular collector for absorbing solar radiation and having a means for securing head and tail stock cap assemblies located respectively at each end of said collector, and including an elongated tubular insulator forming a water storage tank therein, respective to the collector shape and said storage tank having means of thermal insulation, and said insulator providing a means for convectional water flow between an interstitial space positioned between the outer surface of said insulator and the inner wall surface of said collector.

   [2] An integrated solar water heater as claimed in claim [1] whereby said storage tank has means for communicating convectional water flow from said interstitial space positioned between the outer surface of said insulator and inner surface of said collector through a series of water channels located within the insulator and respective to each end of the insulator.

   [3] An integrated solar water heater as claimed in claim [1] and [2] wherein said water channels conveying water convectional flow are located within the storage tank insulator and inclined upwards obliquely.

   [4] An integrated solar water heater as claimed in claim [1] [2]and [3] wherein said insulator has means of support by bridging against the inner surface wall of the collector, and channels formed within these bridge supports to assist convectional water flow.

   [5] An integrated solar water heater as claimed in claim [1] whereby said end caps assemblies have means to secure an outer cover that is transparent to solar radiation and being concentric to the collector, and an arrangement to mechanically seal both the collector and said outer cover onto respective end caps.

   [6] An integrated solar water heater as claimed in claim [1] whereby said end cap assemblies have means for water connections respective for cold intake and hot take off points and a connection on the tailstock end cap for receiving an electric immersion heater.

   [7] An integrated solar water heater as claimed in claim [1] and claim [6] whereby said hot take off pipe is substantially immersed into said formed water storage tank and providing means for an air pocket to be formed and used as a pressure regulator against internal water expansion.

   [8] An integrated solar water heater as claimed in claim [1] [2] and [3] wherein a device shaped to fit around the either the upper or lower water channels is fitted inside the storage tank for preventing reverse water flow to the collector.

   Amendments to the claims have been filed as follows [1] A solar water heater comprising an elongated tubular collector for absorbing solar radiation and having an outer transmission cover for trapping said solar radiation, and having means for hot and cold water take off points located on respective head and tail stock end caps and having means to seal and secure said end caps to said collector, and including an insertable elongated tubular insulator being substantially completely immersed in water and comprising an inner fonned area that provides a water storage tank and an outer formed surface respective to inner formed area whereby an interstitial space is located between the outer surface of the insulator and an inner wall surface of the collector, and such a space providing a means for the action of convectional water flow to take place.

   [2] A solar water heater as claimed in claim I whereby said storage tank has means for communicating convectional water flow from said interstitial space positioned between the outer surface of said insulator and inner surface of said collector.

   [3] A solar water heater as claimed in claim 2 wherein said storage tank has a plastic film mechanism fitted at one end of the said insulator adjacent to the means for communicating convectional water flow and allowing the passage of water though in one direction only and preventing the action of reverse flow.

   [4] A solar water heater as claimed in claim I whereby said end caps assemblies have means to secure an outer cover that is transparent to solar radiation and being concentric to the collector and an arrangement to mechanically seal both the collector and said outer cover onto respective end caps which has means for providing the evacuation of the air space between said collector and outer cover. I.

   [51 A solar water heater as claimed in claim 1 whereby said hot water take off point is substantially immersed into said formed water storage tank and providingmeans foranairpockettobefonnedandusedasap regulator against internal water expansion and for the formation of air bubbles to be contained. S. *0 5)

   CLAIMES

   [1] An integrated solar water heater comprising an elongated tubular collector for absorbing solar radiation and having a means for securing head and tail stock cap assemblies located respectively at each end of said collector, and including an elongated tubular insulator forming a water storage tank therein, respective to the collector shape and said storage tank having means of thermal insulation, and said insulator providing a means for convectional water flow between an interstitial space positioned between the outer surface of said insulator and the inner wall surface of said collector.

   [2] An integrated solar water heater as claimed in claim [1] whereby said storage tank has means for communicating convectional water flow from said interstitial space positioned between the outer surface of said insulator and inner surface of said collector through a series of water channels located within the insulator and respective to each end of the insulator.

   [3] An integrated solar water heater as claimed in claim [1] and [2] wherein said water channels conveying water convectional flow are located within the storage tank insulator and inclined upwards obliquely.

   [4] An integrated solar water heater as claimed in claim [1] [2]and [3] wherein said insulator has means of support by bridging against the inner surface wall of the collector, and channels formed within these bridge supports to assist convectional water flow.

   [5] An integrated solar water heater as claimed in claim [1] whereby said end caps assemblies have means to secure an outer cover that is transparent to solar radiation and being concentric to the collector, and an arrangement to mechanically seal both the collector and said outer cover onto respective end caps.

   [6] An integrated solar water heater as claimed in claim [1] whereby said end cap assemblies have means for water connections respective for cold intake and hot take off points and a connection on the tailstock end cap for receiving an electric immersion heater.

   [7] An integrated solar water heater as claimed in claim [1] and claim [6] whereby said hot take off pipe is substantially immersed into said formed water storage tank and providing means for an air pocket to be formed and used as a pressure regulator against internal water expansion.

   [8] An integrated solar water heater as claimed in claim [1] [2] and [3] wherein a device shaped to fit around the either the upper or lower water channels is fitted inside the storage tank for preventing reverse water flow to the collector.

   Amendments to the claims have been filed as follows [1] A solar water heater comprising an elongated tubular collector for absorbing solar radiation and having an outer transmission cover for trapping said solar radiation, and having means for hot and cold water take off points located on respective head and tail stock end caps and having means to seal and secure said end caps to said collector, and including an insertable elongated tubular insulator being substantially completely immersed in water and comprising an inner fonned area that provides a water storage tank and an outer formed surface respective to inner formed area whereby an interstitial space is located between the outer surface of the insulator and an inner wall surface of the collector, and such a space providing a means for the action of convectional water flow to take place.

   [2] A solar water heater as claimed in claim I whereby said storage tank has means for communicating convectional water flow from said interstitial space positioned between the outer surface of said insulator and inner surface of said collector.

   [3] A solar water heater as claimed in claim 2 wherein said storage tank has a plastic film mechanism fitted at one end of the said insulator adjacent to the means for communicating convectional water flow and allowing the passage of water though in one direction only and preventing the action of reverse flow.

   [4] A solar water heater as claimed in claim I whereby said end caps assemblies have means to secure an outer cover that is transparent to solar radiation and being concentric to the collector and an arrangement to mechanically seal both the collector and said outer cover onto respective end caps which has means for providing the evacuation of the air space between said collector and outer cover. I.

   [51 A solar water heater as claimed in claim 1 whereby said hot water take off point is substantially immersed into said formed water storage tank and providingmeans foranairpockettobefonnedandusedasap regulator against internal water expansion and for the formation of air bubbles to be contained. S. *0 5)