EP2633246A2

EP2633246A2 - A water storage tank and heating apparatus for the water storage tank, and a method for heating water in a water storage tank

Info

Publication number: EP2633246A2
Application number: EP11749002.9A
Authority: EP
Inventors: Kevin John Quinn; Richard Christopher Moore
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-08-09
Filing date: 2011-08-09
Publication date: 2013-09-04
Also published as: WO2012020395A3; WO2012020395A2

Abstract

A water storage tank (1 ) for heating domestic hot water defines a hollow interior region (6) within which heating apparatus (15) is located. The heating apparatus (15) comprises a housing (17) which forms a heat exchanger and comprises an outer cylindrical side wall (19) which extends around and upwardly from a circular base (21) to a top wall (22). Tubes (24) extending through the chamber (20) between the base and top walls (21,22) form passageways (25) for accommodating water from a lower portion (30) of the hollow interior region (6) to an upper portion (35) thereof. Heat exchange water from a boiler is circulated through the chamber (20) which heats water in the passageways (25). The heated water in the passageways (25) rises therethrough and into an outlet chamber (33) and in turn through a first outlet port (34) into the upper portion (35) of the hollow interior region (6). Water from the lower portion (30) of the hollow interior region (6) is drawn into the passageway (25) through first inlet ports (28) for heating thereof. The housing (17) is clad with heat insulating material (43) in order to concentrate heat from the heat exchange water in the chamber (20) into heating water in the passageways (25).

Description

"A water storage tank and heating apparatus for the water storage tank, and a method for heating water in a water storage tank

The present invention relates to a water storage tank for storing and heating water therein, and to heating apparatus for heating water in the water storage tank. The invention also relates to a method for heating water in a water storage tank.

Water storage tanks for storing and heating water are well known. Such water storage tanks are commonly used in domestic dwellings for providing a supply of hot domestic water. Such water storage tanks are commonly referred to as hot tanks, and are provided with a head of water in order to maintain the water storage tank filled with water. The head of water is normally provided by a header tank which is located in the attic of a domestic dwelling and provides the head of water to the water storage tank. Water in the water storage tank is heated by a suitable heating means, which may comprise an electrically powered immersion heater, an electrically powered heating element of which extends into the hollow interior region of the storage tank for heating water therein.

Alternatively, or additionally, a heat exchanger may be located in the hollow interior region which comprises a heating coil through which a heat exchange medium is circulated for transferring heat into the water in the hollow interior region of the storage tank. The heat exchange medium is typically hot water which is circulated through the heat exchange coil from a central heating boiler, or a back boiler of an open fireplace or a stove.

Such storage tanks within which water is heated suffer from a number of disadvantages, a particularly serious disadvantage of such storage tanks is the length of time required to produce hot water at a suitable temperature from cold. This is largely due to the volume of water which must be heated in the storage tank before water at a desired temperature is produced from the storage tank. Typically when all the water in the storage tank is at room temperature, it can take up to 60 minutes or more for hot water at a suitable temperature, typically of the order of 45°C, to be produced from the storage tank. Indeed, if draw-off of water commences immediately the temperature of the water produced by the storage tank reaches such a suitable temperature, the heating arrangement in the storage tank, be it a heat exchanger or an immersion heater, in general is incapable of maintaining the temperature of the water being drawn off from the storage tank. In order to reach a stage where a significant quantity of hot water can be continuously drawn off from storage tanks known heretofore, it is necessary to have a corresponding body of water in the storage tank heated to such a suitable temperature. Otherwise, as soon as the body of water in the storage tank at the desired temperature has been drawn off, the temperature of the water being drawn off will commence to drop, and the heating arrangement will be unable to maintain the temperature of the water being drawn off at the desired suitable temperature. This is undesirable.

There is therefore a need for a water storage tank which addresses this problem. There is also a need for a heating apparatus for a water storage tank which likewise addresses the problem, and there is a need for a method for heating water in a water storage tank which addresses the problem.

The present invention is directed towards providing such a water storage tank, a heating apparatus and a method for heating water in a water storage tank.

According to the invention there is provided heating apparatus adapted for locating in a water storage tank defining a hollow interior region for heating water in the hollow interior region of the storage tank, the heating apparatus comprising a housing adapted for mounting in the hollow interior region of the storage tank, at least one elongated passageway extending through the housing adapted to accommodate water through the housing from a lower portion of the hollow interior region of the storage tank to an upper portion thereof, a first inlet port to the at least one passageway adapted to communicate the passageway with the lower portion of the hollow interior region of the storage tank, a first outlet port from the at least one passageway adapted to communicate the passageway with the upper portion of the hollow interior region of the storage tank, and a heating means in the housing adapted to heat water in the at least one passageway, so that water heated in the passageway is urged by convection through the passageway to the upper portion of the hollow interior region of the storage tank through the first outlet port.

In one embodiment of the invention the heating means extends at least partly around the at least one passageway. Preferably, the heating means extends completely around the at least one passageway. Advantageously, the heating means extends substantially the length of the at least one passageway.

In one embodiment of the invention the heating means comprises a heat exchanger. In another embodiment of the invention the housing comprises a chamber of the heat exchanger adapted to accommodate a heat exchange medium, a second inlet port communicating with the chamber for accommodating the heat exchange medium to the chamber, and a second outlet port communicating with the chamber for accommodating the heat exchange medium from the chamber, the chamber co- operating with the at least one passageway for transferring heat from the heat exchange medium to water in the passageway.

Preferably, the housing comprises at least one partition wall separating the at least one passageway from the chamber, the partition wall being of a heat conducting material and being adapted to transfer heat from the heat exchange medium to water in the passageway. Advantageously, a plurality of passageways extend through the housing. Ideally, each passageway extends through the chamber, and one of the partition walls extends around each passageway to separate the corresponding passageway from the chamber.

In one embodiment of the invention the passageways are configured in an array, the array comprising one of the passageways being centrally located and a plurality of the passageways arranged along a pitch circle concentric with the central one of the passageways, the passageways arranged along the pitch circle being spaced apart from each other and spaced apart from the central one of the passageways.

Preferably, a plurality of the passageways are arranged along a plurality of radially spaced apart pitch circles concentric with the central one of the passageways.

Advantageously, each passageway is of circular transverse cross-section. In another embodiment of the invention at least two chambers are provided, the chambers defining the at least one passageway therebetween. In a further embodiment of the invention one of the chambers is of annular construction extending around the other one of the chambers, and defining with the said other one of the chambers the passageway as an annular passageway.

Preferably, each of the chambers is of annular construction, one of the chambers extending around the other of the chambers and defining with the said other of the chambers one of the passageways as an annular passageway, the said other of the chambers defining another one of the passageways as a central passageway extending through the said other of the chambers. Advantageously, a plurality of the chambers are provided, the chambers being of annular construction, each chamber extending around the next adjacent chamber, and defining with the next adjacent chamber the passageway as an annular passageway. Preferably, the chambers are concentric with each other and radially spaced apart from each other.

In another embodiment of the invention the chamber is configured as a helical chamber.

In a further embodiment of the invention the at least one passageway is configured as a helical passageway.

In one embodiment of the invention the heat exchanger is adapted to receive heat exchange medium from a boiler.

In another embodiment of the invention the heat exchanger is adapted to receive heat exchange medium from a solar panel. In a further embodiment of the invention the heat exchange medium comprises water.

In another embodiment of the invention the housing comprises one passageway, and the heating means is located in the passageway. Preferably, the heating means comprises an electrically powered heating means. Advantageously, the heating means comprises an electrically powered heating element encased in a heat transfer casing. Ideally, the heating means comprises an immersion heater.

Preferably, the heating means extends substantially the length of the passageway.

In one embodiment of the invention the housing is adapted for mounting in the hollow interior region of the storage tank with the at least one passageway extending substantially vertically.

In another embodiment of the invention the housing is adapted for mounting in the hollow interior region of the storage tank with the at least one passageway extending substantially horizontally.

In a further embodiment of the invention the housing is adapted for mounting in the hollow interior region of the storage tank with the at least one passageway extending in a general direction inclined to the horizontal. In one embodiment of the invention the sum of the volumes of the one or more passageways is significantly less than the volume of the hollow interior region of the storage tank. Preferably, the sum of the volumes of the one or more passageways is not more than 10% of the volume of the hollow interior region of the tank.

Advantageously, the sum of the volumes of the one or more passageways is not more than 5% of the volume of the hollow interior region of the tank. Ideally, the sum of the volumes of the one or more passageways is not more than 1 % of the volume of the hollow interior region of the tank.

In one embodiment of the invention the housing comprises an outer casing.

Preferably, the outer casing comprises a base wall, a spaced apart top wall, and a side wall extending around the base wall and the top wall and extending from the base wall to the top wall. Advantageously, the first inlet port is located in the base wall of the outer casing, and the first outlet port extends from the top wall of the outer casing.

In another embodiment of the invention the first inlet port is located in the side wall of the outer casing, and the first outlet port is located in the side wall of the outer casing.

In a further embodiment of the invention the second inlet port and the second outlet port extend from the side wall of the outer casing. Preferably, the housing is clad in a heat insulating material.

In one embodiment of the invention the heating means and the passageway cooperate to form a thermosyphon in the passageway for urging water through the passageway from the first inlet port to the first outlet port.

The invention also provides a storage tank for storing water to be heated therein, the storage tank defining a hollow interior region having an upper portion and a lower portion, and a heating apparatus according to the invention located in the hollow interior region of the storage tank with the first inlet port adapted to communicate the first passageway with the lower portion of the hollow interior region of the storage tank for accommodating water from the lower portion of the hollow interior region of the storage tank into the at least one passageway, and the first outlet port being adapted to communicate the at least one passageway with the upper portion of the hollow interior region of the storage tank for accommodating water from the at least one passageway to the upper portion of the hollow interior region of the storage tank.

Preferably, an inlet pipe extends through a wall of the storage tank to the second inlet port of the housing for accommodating heat exchange medium into the chamber of the heat exchanger, and an outlet pipe extends through the wall of the storage tank from the second outlet port for accommodating the heat exchange medium from the chamber of the heat exchanger. Additionally the invention provides a water storage tank defining a hollow interior region and comprising a lower main inlet port to the hollow interior region for accommodating water into the hollow interior region adjacent a lower portion thereof, an upper main outlet port from the hollow interior region for accommodating water from the hollow interior region adjacent an upper portion thereof, a heating apparatus mounted in the hollow interior region for heating water therein, the heating apparatus comprising a housing mounted in the hollow interior region of the storage tank, at least one elongated passageway extending through the housing adapted to accommodate water through the housing from the lower portion of the hollow interior region of the storage tank to the upper portion of the hollow interior region of the storage tank, a first inlet port to the at least one passageway communicating the passageway with the lower portion of the hollow interior region of the storage tank, a first outlet port from the at least one passageway communicating the passageway with the upper portion of the hollow interior region of the storage tank, and a heating means in the housing adapted to heat water in the at least one passageway, so that water heated in the passageway is urged by convection through the passageway to the upper portion of the hollow interior region of the storage tank through the first outlet port. In one embodiment of the invention the heating apparatus is located in an intermediate portion of the hollow interior region of the storage tank between the lower portion of the hollow interior region and the upper portion thereof.

In one embodiment of the invention the first outlet port extending from the heating apparatus terminates at a level in the hollow interior region of the storage tank a vertical distance below the level of the main outlet port from the hollow interior region of not more than 15% of the vertical height of the hollow interior region of the storage tank. Preferably, the first outlet port extending from the heating apparatus terminates at a level in the hollow interior region of the storage tank a vertical distance below the level of the main outlet port from the hollow interior region of not more than 10% of the vertical height of the hollow interior region of the storage tank. Advantageously, the first outlet port extending from the heating apparatus terminates at a level in the hollow interior region of the storage tank a vertical distance below the level of the main outlet port from the hollow interior region of not more than 5% of the vertical height of the hollow interior region of the storage tank.

In one embodiment of the invention the upper portion of the hollow interior region of the storage tank is defined between the main outlet port and the first outlet port. Preferably, the first inlet port to the heating apparatus is at a level spaced apart a vertical distance above the level of the main inlet port of not more than 15% of the vertical height of the hollow interior region of the storage tank.

Advantageously, the first inlet port to the heating apparatus is at a level spaced apart a vertical distance above the level of the main inlet port of not more than 10% of the vertical height of the hollow interior region of the storage tank.

Ideally, the first inlet port to the heating apparatus is at a level spaced apart a vertical distance above the level of the main inlet port of not more than 5% of the vertical height of the hollow interior region of the storage tank, and may be less than 5% of the vertical height of the hollow interior region of the storage tank.

In another embodiment of the invention the lower portion of the hollow interior region of the storage tank is defined between the first inlet port and a base of the water storage tank.

In a further embodiment of the invention the hollow interior region of the storage tank is of circular transverse cross-section, and comprises a base and a top wall which are circular when viewed in plan.

In one embodiment of the invention the top wall is of domed shape, and the main outlet port extends substantially centrally from the top wall. Preferably, the storage tank is externally clad with a heat insulating material.

In one embodiment of the invention two heating apparatus are located in the hollow interior region of the storage tank, one of the heating apparatus comprising a heating means located in the passageway of the housing of the heating apparatus, and the other heating apparatus comprising the heat exchanger.

The invention also provides a method for heating water in a water storage tank which defines a hollow interior region for the water, providing a heating apparatus in the hollow interior region, wherein the heating apparatus comprises a housing, at least one elongated passageway extending through the housing adapted to accommodate water therethrough and terminating at one end in a first inlet port and at another end in a first outlet port, and a heating means in the housing adapted to heat water in the at least one passageway, locating the heating apparatus in the hollow interior region of the storage tank with the first inlet port located adjacent a lower portion of the hollow interior region, and the first outlet port located adjacent an upper portion of the hollow interior region, so that water in the at least one passageway is heated by the heating means and is urged by convection through the passageway to the upper portion of the hollow interior region of the storage tank through the first outlet port.

The advantages of the invention are many. The water storage tank according to the invention is capable of producing hot water at a suitable desirable temperature of approximately 60°C from cold within approximately five minutes of powering up of the immersion heater or activation of the heat exchanger. Furthermore, the water storage tank according to the invention is capable of producing a continuous supply of hot water at a suitable desirable temperature of the order of 60°C at a rate of approximately one litre per minute. These advantages are achieved by virtue of the fact that the heat exchange apparatus comprises at least one passageway through which water is accommodated from a lower portion of the hollow interior region of the storage tank to an upper portion thereof and the heating means heats water in the passageway which is urged by convention through the passageway and through the first outlet port from the passageway into the upper portion of the hollow interior region, so that only a small volume of water, namely, the volume of water in the upper portion of the hollow interior region requires to be heated, in order to maintain the temperature of the water being drawn off at a suitable desirable temperature. Where greater volumes of water are required to be continuously drawn off from the tank at suitable desirable temperatures, more than one passageway may be required through the heating apparatus, and the heat output produced by the heating means may have to be increased. However, the heat output required to maintain the temperature of water being continuously drawn off from the storage tank according to the invention is significantly less than that which would be required by a conventional storage tank with a conventional heat exchanger and/or a conventional immersion heater.

The rapid rate at which hot water at a suitable desirable temperature is produced from cold by the storage tank according to the invention is largely due to the relatively small volume of the passageway or passageways, as the case may be, of the heating apparatus also according to the invention. In general, the volume of the passageway, or the sum of the volumes of the passageways of the heating apparatus is not more than 1 %, and in general, is less than 1% of the total volume of the hollow interior region of the storage tank. Accordingly, the quantity of heat which is available from the heating apparatus is required to heat a significantly smaller volume of water in order to produce water ready to be drawn off at a suitable desirable temperature from the storage tank than is required in storage tanks known heretofore, where the volume of water to be heated by a heat exchanger or other heating means which is located in the hollow interior region of storage tanks known heretofore is required to heat a significantly larger volume of water before the temperature of water available for drawing off from the storage tanks known heretofore is at a suitable desirable temperature.

Furthermore, because the heat available from the heating apparatus according to the invention is required to heat a relatively small volume of water, virtually every unit of heat available from the heating apparatus is transferred to the water to be heated in the passageway or passageways of the heating apparatus. This also produces a relatively fast recovery rate in cases where excessive volumes of water are drawn off from the storage tanks according to the invention, or where the draw-off rate of water from the storage tanks according to the invention is excessive.

The invention will be more clearly understood from the following description of some preferred embodiments thereof, which are given by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a cutaway perspective view of a water storage tank according to the invention incorporating heating apparatus also according to the invention,

Fig. 2 is a cross-sectional front elevational view of the storage tank of Fig. 1 ,

Fig. 3 is a see-through perspective view of the heating apparatus of the storage tank of Fig. 1 ,

Fig. 4 is a front elevational view of the heating apparatus of Fig. 3,

Fig. 5 is a partly cross-sectional front elevational view of the heating apparatus of Fig. 3,

Fig. 6 is a see-through perspective view of a portion of the heating apparatus of Fig. 3,

Fig. 7 is a top plan view of the portion of Fig. 6 of the heating apparatus of Fig. 3,

Fig. 8 is an underneath plan view of the heating apparatus of Fig. 3,

Fig. 9 is a transverse cross-sectional underneath plan view of the portion of Fig. 6 of the heating apparatus of Fig. 3 on the line IX-IX of Fig. 6,

Fig. 10 is a cutaway perspective view of a water storage tank according to another embodiment of the invention comprising a heating apparatus also according to another embodiment of the invention,

Fig. 11 is a perspective view of the heating apparatus of Fig. 10, Fig. 12 is an underneath perspective view of a portion of the heating apparatus of Fig. 11 ,

Fig. 13 is another underneath perspective view of a portion of the heating apparatus of Fig. 11 ,

Fig. 14 is a cutaway perspective view of the heating apparatus of Fig. 11 ,

Fig. 15 is a cutaway perspective view of a portion of the heating apparatus of Fig. 11 ,

Fig. 16 is a perspective view of a portion of the heating apparatus of Fig. 11 ,

Fig. 17 is a perspective view of a portion of the heating apparatus of Fig. 11 , Fig. 18 is another perspective view of the heating apparatus of Fig. 11 ,

Fig. 19 is a cutaway perspective view of a portion of the heating apparatus of Fig. 11 , Fig. 20 is a cross-sectional front elevational view of a water storage tank according to another embodiment of the invention incorporating two heating apparatus, both of which are according to the invention,

Fig. 21 is a transverse cross-sectional plan view of the water storage tank of Fig. 20 on the line XXI-XXI of Fig. 20,

Fig. 22 is a cross-sectional front elevational view of one of the heating apparatus of Fig. 20, Fig. 23 is a top plan view of the heating apparatus of Fig. 22,

Fig. 24 is an underneath plan view of the heating apparatus of Fig. 22,

Fig. 25 is a transverse cross-sectional plan view of the heating apparatus of Fig. 22 on the line XXV-XXV of Fig. 22,

Fig. 26 is a transverse cross-sectional plan view of the heating apparatus of Fig. 22 on the line XXVI-XXVI of Fig. 22,

Fig. 27 is a cutaway perspective view of a portion of a water storage tank according to another embodiment of the invention incorporating heating apparatus also according to another embodiment of the invention,

Fig. 28 is a cross-sectional top plan view of the portion of the water tank of Fig. 27,

Fig. 29 is a cutaway perspective view of a portion of a water tank according to a further embodiment of the invention incorporating heating apparatus also according to a further embodiment of the invention,

Fig. 30 is a cross-sectional plan view of the portion of the storage tank of Fig. 29,

Fig. 31 is a cross-sectional front elevational view of a water storage tank according to another embodiment of the invention incorporating a heating apparatus also according to another embodiment of the invention,

Fig. 32 is a cross-sectional top plan view of the storage tank of Fig. 31 ,

Fig. 33 is a cutaway perspective view of a water storage tank according to another embodiment of the invention, Fig. 34 is a cross-sectional side elevational view of the water storage tank of Fig. 33, Fig. 35 is a transverse cross-sectional end elevational view of a portion of the water storage tank of Fig. 33, and

Fig. 36 is a perspective view of a portion of a heat exchanger of the water storage tank of Fig. 33.

Referring to the drawings and initially to Figs. 1 to 9 thereof, there is illustrated a water storage tank according to the invention, indicated generally by the reference numeral 1 , for storing and heating water. The water storage tank 1 is particularly suitable for use in a domestic hot water supply system, and is of the type which is commonly referred to as a hot tank. Typically, the water storage tank 1 is supplied with water from a header tank (not shown) which provides a head of water to the water storage tank, so that domestic hot water supplied from the water storage tank 1 is supplied therefrom at a head corresponding to the head produced by the header tank (not shown). The water storage tank 1 comprises a base 3 which is circular and of dome shape and is concave when viewed from below. A cylindrical side wall 4 extends around the base 3 and upwardly therefrom and terminates in a top wall 5, which in this embodiment of the invention is planar and circular. The base 3, side wall 4 and top wall 5 together define a hollow interior region 6 for the water, and in which the water is heated.

A main inlet port 8 in the side wall 4 towards the base 3 accommodates water to be stored and heated in the storage tank 1 into the hollow interior region 6. A main outlet port 9 extending from the top wall 5 accommodates heated water for domestic use from the hollow interior region 6 of the water storage tank 1. Typically, the base 3, side wall 4 and top wall 5 are of copper, although it will be readily appreciated that the water storage tank 1 may be of any other suitable material.

The top wall 5 and the side wall 4 are clad with a heat insulating material 10. The heat insulating material extends completely around the side wall 4 from the base 3 to the top wall 5. An outer shell 12 of a metal foil material extends completely around the heat insulating material 10 so that the heat insulating material 10 is sandwiched between the outer shell 12 and the side wall 4.

Heating apparatus, also according to the invention and indicated generally by the reference numeral 15, is located in the hollow interior region 6 of the water storage tank 1 for heating water therein. The heating apparatus comprises a housing 17 which comprises a cylindrical side wall 19 of copper which forms a chamber 20 of circular horizontal transverse cross-section. The side wall 19 extends around and upwardly from a circular planar base wall 21 of copper to a circular planar top wall 22 also of copper, so that the side wall 19 with the base wall 21 and the top wall 22 defines the chamber 20. A plurality of tubes 24 of copper and of circular transverse cross-section extend through the chamber 20 between the base wall 21 and the top wall 22 and are sealably secured to the base and top walls 21 and 22 so that the chamber 20 is watertight. The tubes 24 define respective vertically extending passageways 25 which extend through the chamber 20 from the base wall 21 to the top wall 22 between respective first lower inlet ports 27 adjacent the base wall 21 and respective upper outlets 28 adjacent the top wall 22. The first lower inlet ports 27 communicate the passageways 25 with a lower portion 30 of the hollow interior region 6 of the storage tank 1. A frustoconical shaped top wall 32 of copper is also sealably secured to the side wall 19 of the housing 17 and defines with the top wall 22 an outlet chamber 33 communicating with the passageways 25 through the upper outlets 28. A first outlet port 34 extends centrally from the frustoconical top wall 32 and communicates the passageways 25 through the outlet chamber 33 with an upper portion 35 of the hollow interior region 6 of the storage tank 1 , so that water admitted into the passageways 25 through the first lower inlet ports 27 from the lower portion 30 of the hollow interior region 6 is delivered into the upper portion 35 of the hollow interior region 6.

In this embodiment of the invention the heating apparatus 15 comprises a heat exchanger 41 which is formed by the chamber 20 and the passageways 25. The chamber 20 is adapted to accommodate a heat exchange medium, which in this embodiment of the invention is circulated through the chamber 20 from a gas or oil fired boiler and/or a back boiler of an open fireplace and/or a stove (none of which boilers are shown). A second inlet port 36 in the side wall 19 of the housing 17 accommodates the heat exchange water from the boiler or boilers into the chamber 20, and a second outlet port 37 in the side wall 19 accommodates the heat exchange water from the chamber 20 back to the boiler. An inlet pipe 38 extends from the second inlet port 36 sealably through an opening 46 in the side wall 4 of the storage tank 1 , and in turn through the heat insulating material 10 and the shell 12 of the storage tank 1 for connecting to a supply pipe supplying heat exchange water from the boiler or boilers. An outlet pipe 39 extends from the second outlet port 37 sealably through an opening 47 in the side wall 4 of the storage tank 1 and in turn through the heat insulating material 10 and the shell 12 of the storage tank 1 for connecting to a return water pipe for returning heat exchange water to the boiler or boilers.

In this embodiment of the invention the side wall 19 is sealably brazed to the base wall 21 , the top wall 22 and the dome shaped top wall 32. The tubes 24 are sealably brazed to the base and top walls 21 and 22, and the primary outlet port 34 is also sealably brazed to the dome shaped top wall 32.

In this embodiment of the invention the passageways 25 are configured as an array, in which one of the passageways 25 is centrally located in the chamber 20, namely, a central one 25a of the passageways 25, and the remaining passageways are formed on two pitch circles, namely, an inner pitch circle and an outer pitch circle, which extend concentrically around the central passageway 25a with the

passageways 25 of each pitch circle spaced apart from each other and spaced apart from the central passageway 25a and the passageways 25 of the other pitch circle. The passageways 25 of the inner pitch circle are identified by the reference numeral 25b, while the passageways 25 of the outer pitch circle are identified by the reference numerals 25c. The tubes 24 being of copper are of a heat conducting material, and thus form heat conducting partition walls 42 between the chamber 20 and the corresponding passageways 25 through which heat is conducted from the heat exchange water in the chamber 20 to water in the passageways 25, so that water heated in the passageways 25 passes upwardly through natural convection and exits through the upper outlets 28 into the outlet chamber 33 and in turn through the first outlet port 34 into the upper portion 35 of the hollow interior region 6 of the storage tank 1.

The upper portion 35 of the hollow interior region 6 of the storage tank 1 is defined between the first outlet port 34 of the heating apparatus 15 and the main outlet port 9 from the storage tank 1. The lower portion 30 of the hollow interior region 6 of the storage tank 1 is defined between the main inlet port 8 to the hollow interior region 6 and the lower first inlet ports 27 to the passageway 25. Thus, the heating apparatus 15 is located in an intermediate portion 40 of the hollow interior region 6 which extends between the lower portion 30 and the upper portion 35 of the hollow interior region 6 of the storage tank 1.

In this embodiment of the invention nineteen passageways 25 extending through the housing 17 are provided, and the internal diameter of each passageway 25 is approximately 12mm, and each passageway 25 is approximately 550mm in length. The diameter of the chamber 20 is 75mm. The diameter of the hollow interior region 6 of the storage tank 1 is 500mm, and the overall vertical height of the hollow interior region 6 of the storage tank 1 from the base 3 at the centre thereof to the top wall 5 is approximately 800mm. Accordingly, in this embodiment of the invention the sum of the volumes of the nineteen passageways 25 is approximately 0.75% of the total volume of the hollow interior region 6 of the storage tank 1. In this embodiment of the invention the height of the housing from the base wall 21 to the first outlet port 34 is approximately 600mm. The vertical distance between the first outlet port 34 and the main outlet port 9 from the hollow interior region 6 is approximately 40mm, which is thus approximately 5% of the overall vertical height of the hollow interior region 6 of the storage tank 1. The base wall 21 is approximately 40mm vertically above the centre of the base 3 of the storage tank 1. Accordingly, in this embodiment of the invention the vertical distance between the central portion of the base 3 and the base wall 21 of the housing 17 is approximately 5% of the overall vertical height of the hollow interior region 6.

It has been found that by keeping the sum of the volumes of the passageways 25 at a relatively small percentage of the total volume of the hollow interior region 6 of the storage tank 1 within reason, a particularly desirable and efficient storage tank 1 according to the invention is provided. While in this embodiment of the invention the sum of the volumes of the passageways 25 is approximately 0.75% of the total volume of the hollow interior region 6 of the tank 1, it is desirable that the sum of the volumes of the passageways 25 should preferably not exceed 1 % of the total volume of the hollow interior region 6 of the storage tank, although it has been found that reasonable results and efficiencies can be achieved by maintaining the volume of the passageways below 15% of the total volume of the hollow interior region of the storage tank, but ideally, in order to obtain reasonable results and efficiencies, the sum of the volumes of the passageways should not exceed 5% of the total volume of the hollow interior region of the storage tank.

The side wall 19 and the frustoconical shaped top wall 32 are completely clad with heat insulating material 43 in order to concentrate heat from the heat exchange water in the chamber 20 into heating water in the passageways 25, and to minimise direct heat transfer into the water which is in the storage tank externally of the heating apparatus 15. An outer shell 44 extending around and over the heat insulating material 43 sandwiches the heat insulating material 43 between the outer shell 44 and the side wall 19 and the top wall 22 so that the majority of heat in the heat exchange water in the chamber 20 is transferred into the water in the passageways 25, and not into the water in the intermediate portion 40 of the hollow interior region 6 of the storage tank 1 externally of the heating apparatus 15.

It will be appreciated that the diameter of the water storage tank 1 may be greater or less than 500mm, and additionally, the vertical height of the hollow interior region 6 may be greater or less than 800mm. The size of the storage tank 1 will largely be dependent on the domestic hot water requirements of the dwelling in which the storage tank 1 is located. Additionally, the number of passageways 25, and the diameter and lengths of the passageways 25 typically will vary depending on the capacity of the storage tank 1 , as will the capacity of the chamber 20 of the heating apparatus 15. In use, with the main inlet port 8 of the storage tank 1 connected to the header tank (not shown) and the main outlet port 9 of the storage tank 1 connected to a supply pipe which supplies domestic hot water, and with the second inlet port 36 of the heating apparatus 15 connected to the flow water outlet port of the boiler or boilers (not shown) and the second outlet port 37 of the heating apparatus 15 connected to the return inlet port of the boiler or boilers (not shown), the storage tank 1 is ready for use. As heat exchange water is being circulated through the chamber 20 from the boiler or boilers (not shown) at a higher temperature than the water in the passageways 25, heat is transferred from the heat exchange water in the chamber 20 through the partition walls 42 formed by the tubes 24 into water in the

corresponding passageways 25.

As the water in the passageways 25 commences to heat, the water is urged by natural convection upwardly through the passageways 25 and through the upper outlets 28 and in turn into the outlet chamber 33 and in turn into the upper portion 35 of the hollow interior region 6 of the storage tank 1 through the first outlet port 34. The heated water exiting through the first outlet port 34 rises in the upper portion 35 of the hollow interior region 6 of the storage tank 1 until the temperature of the water in the upper portion 35 of the hollow interior region 6 substantially equalises. The rising water in the passageways 25 results in water from the lower portion 30 of the hollow interior region 6 of the storage tank 1 being drawn into the passageways 25 through the lower first inlet ports 27, thus resulting in the creation of a thermosyphon. Accordingly, if water is not drawn off from the storage tank 1 through the main outlet port 9, the thermosyphon results in the hot water in the upper portion 35 of the hollow interior region 6 being drawn downwardly into the intermediate portion 40 of the hollow interior region 6, and in turn into the lower portion 30 of the hollow interior region 6 until all the water in the hollow interior region 6 of the storage tank 1 is substantially at the same temperature, allowing for a small temperature gradient. As water is drawn off from the storage tank 1 through the main outlet port 9, the temperature gradient from the upper portion 35 to the lower portion 30 of the hollow interior region 6 increases, thereby resulting in reactivation of the thermosyphon through the passageways 25. When all the water in the hollow interior region 6 of the tank 1 is cold, it has been found that within five minutes after commencement of supply of the heat exchange water to the heating apparatus 1 , hot water at a temperature of 60°C can be continuously drawn off from the main outlet port 9 of the storage tank 1 at a rate of approximately one litre per minute. This is achieved by virtue of the fact that the volume of water to be heated in the passageways 25 is relatively small, and the heat available in the heating apparatus 15 is concentrated into the relatively small volume of the passageways 25. By virtue of the small volume of water in the passageways 25 to be heated, the water being heated by the heat exchanger 41 can be heated at a much more rapid rate, thereby permitting water to be drawn off at a temperature of approximately 60°C and at a rate of approximately one litre per minute within approximately five minutes of the commencement of circulation of the heat exchange water through the heating apparatus 15.

Referring now to Figs. 10 to 19, there is illustrated a water storage tank according to another embodiment of the invention, indicated generally by the reference numeral 50. The water storage tank 50 is substantially similar to the water storage tank 1 and similar components are identified by the same reference numerals. In this embodiment of the invention a heating apparatus also according to the invention and indicated generally by the reference numeral 51 is located in the hollow interior region 6 of the storage tank 50 for heating the water therein. The heating apparatus 51 comprises a housing 52 which defines a main passageway 53 which extends substantially horizontally in the hollow interior region 6, and a plurality of secondary passageways 54 extending generally vertically upwardly from the main passageway 53 to an upwardly inclined manifold 55 which terminates in a vertically upwardly extending passageway 56. The upwardly extending passageway 56 terminates in a first outlet port 58 which communicates with the upper portion 35 of the hollow interior region 6. A plurality of first inlet ports 59 communicate the main passageway 53 with the lower portion 30 of the hollow interior region 6. In this embodiment of the invention a heating means is located in the main passageway 53 for heating water therein and is provided by an immersion heater 61 comprising encased electrical heating elements 60 extending into the passageway 56 from one end thereof. Electrical control apparatus 62 of the immersion heater 61 is housed in a housing 63 which extends outwardly through an opening 64 in the side wall 4 of the storage tank 50 and in turn through the heat insulating material 10 and the outer shell 12. The secondary passageways 54, the manifold 55 and the upwardly extending passageway 56 are all clad in heat insulating material 66. The main passageway 53 is also clad in heat insulating material 66 with the exception of a longitudinally extending portion 65 thereof through which the first inlet ports 59 communicate with the lower portion 30 of the hollow interior region 6 of the storage tank 50. A metal foil shell 67 encases the heat insulation material 66. In this embodiment of the invention the lower portion 30 of the hollow interior region 6 of the storage tank 1 is defined between the first inlet ports 59 and the base 3, while the upper portion 35 of the hollow interior region 6 is defined between the first outlet port 58 and the top wall 5 of the storage tank 50.

In use, on powering up of the heating element 60, water commences to heat in the passageway 56 which is urged by natural convection through the secondary passageways 54, the manifold 55 and the upwardly extending passageway 56 and through the first outlet port 58 into the upper portion 35 of the hollow interior region 6. Water is drawn into the main passageway 53 through the first inlet ports 59. Otherwise, operation of the water storage tank 50 is similar to that described with reference to the water storage tank 1.

In the event that no water is drawn from the storage tank 50, once the temperature of the water in the upper portion 35 has substantially equalised, the rising water in the secondary passageways 54, the manifold 55 and the upwardly extending passageway 56 results in a thermosyphon, which in turn results in the hot water from the upper portion 35 of the hollow interior region being drawn downwardly into the intermediate portion 40 and in turn into the lower portion 30 of the hollow interior region 6 as the water from the lower portion 30 continues to be drawn into the main passageway 53 through the first inlet ports 59.

When water is drawn off from the water storage tank 50 through the main outlet port 9, it has been found that water of a temperature of the order of 40°C can be drawn off at a continuous rate of approximately one litre per minute within twenty minutes of commencement of powering up from cold of the heating element 60. However, in this embodiment of the invention the immersion heater was a 2 kilowatt heater, and it is envisaged that by providing an immersion heater of a higher heat output, the temperature of the water could be produced at a higher desirable temperature, and could be produced from cold in considerably less than twenty minutes. It is also envisaged that by reducing the number of secondary passageways 54 from four to one, it is envisaged that the temperature of the water produced from the water storage tank 50 could be increased and the time to bring the water up to temperature from cold could be decreased for the same heat input.

Referring now to Figs. 20 to 26, there is illustrated a water storage tank according to another embodiment of the invention, indicated generally by the reference numeral 70. The water storage tank 70 is substantially similar to the water storage tank 1 , and similar components are identified by the same reference numerals. In this embodiment of the invention two heating apparatus, which are both according to the invention and indicated generally by the reference numerals 71 and 72, respectively, are located in the hollow interior region 6. The heating apparatus 71 comprises a heating means which is provided by a heat exchanger 76, while the heating apparatus 72 comprises a heating means which is provided by an encased electrically powered heating element 73 of an immersion heater 74. Before describing the heating apparatus 72, the heating apparatus 71 will first be described.

The heating apparatus 71 is somewhat similar to the heating apparatus 15 of the storage tank 1 , in that the heating apparatus 71 a comprises a housing 75. In this embodiment of the invention the housing 75 comprises an inner cylindrical side wall 77 which forms an inner cylindrical chamber 78 for heat exchange water from a boiler. A cylindrical outer side wall 79 concentric with the inner side wall 77 extends around the inner side wall 77 and is spaced apart therefrom. A first intermediate cylindrical side wall 80 and a second intermediate cylindrical side wall 81 which are spaced apart from each other and spaced apart from the inner and outer side walls 79 and are concentric with the inner side wall 77, together form an inner annular chamber 82 for accommodating heat exchange water which is spaced apart from the inner chamber 78 and is concentric therewith. A third intermediate cylindrical side wall 84 which is located between the second intermediate side wall 81 and the outer side wall 79 and is spaced apart from the second intermediate side wall 81 and the outer side wall 79 and is concentric therewith forms with the outer side wall 79 an outer annular chamber 85 for accommodating exchange water.

A top wall 87 closes the top end of the inner chamber 78, the inner annular chamber 82 and the outer annular chamber 85. A base wall 88 closes the inner chamber 78, the inner annular chamber 82 and the outer annular chamber 85 adjacent the lower end thereof.

Two annular passageways 90, namely, an inner annular passageway 90a and an outer annular passageway 90b, are defined between the inner chamber 78, the inner annular chamber 82 and the outer annular chamber 85, respectively, and extend vertically for accommodating water therethrough from the lower portion 30 of the hollow interior region 6 of the storage tank 70 to the upper portion 35 of the hollow interior region 6. Annular openings 92 in the base wall 88 form first inlet ports 93 to the annular passageways 90 from the lower portion 30 of the hollow interior region 6 for communicating the annular passageways 90 with the lower portion 30 of the hollow interior region 6 of the storage tank 70.

A manifold 94 adjacent the upper end of the annular passageways 90 communicate the annular passageways 90 with each other, and a first outlet port 95 extends from the manifold 94 for communicating the annular passageways 90 through the manifold 94 with the upper portion 35 of the hollow interior region 6.

A second inlet port 96 accommodates heat exchange water into the outer annular chamber 85, and a manifold 97 communicates the inner annular chamber 82 and the inner chamber 78 with the second inlet port 96 for accommodating the heat exchange water into the inner annular chamber 82 and the inner chamber 78.

A second outlet port 98 extends from the outer annular chamber 85 for

accommodating heat exchange water from the outer annular chamber 85 to be returned to the boiler. A manifold 99 adjacent the lower end of the housing 75 communicates the outer annular chamber 85 with the inner annular chamber 82 and the inner chamber 78 for accommodating heat exchange water from the inner annular chamber 82 and the inner chamber 78 to the second outlet port 98 to be returned to the boiler. In this embodiment of the invention the material of the housing is copper, and the inner side wall 78 as well as the first, second and third intermediate side walls 80, 81 and 84, respectively, are also of copper to provide heat transfer partition walls for conducting heat from the heat exchange water in the inner chamber 78, the inner annular chamber 82 and the outer annular chamber 85 to water in the inner and outer annular passageways 90a and 90b.

An inlet pipe 38 similar to the inlet pipe 38 of the storage tank 1 extends from the second inlet port 96 through an opening 46 in the side wall 4 of the storage tank 70 for accommodating heat exchange water to the second inlet port 96. An outlet pipe 39 similar to the outlet pipe 39 of the storage tank 1 extends from the second outlet port 98 through an opening 47 in the side wall 4 of the storage tank 70 for accommodating heat exchange water from the second outlet port 98 for return to the boiler.

The outer side wall 79 of the housing 75 is completely clad in heat insulating material 100 which extends completely around the outer side wall 79 and along the length of the outer side wall 79. The top wall 87 as well as the first outlet port 95 are both clad wit heat insulating material. An outer shell 101 of metal foil sandwiches the heat insulating material 100 between the outer shell 101 and the outer side wall 79, the top wall 87 and the first outlet port 95.

As water in the inner and outer annular passageways 90a and 90b is heated by the heat exchange water in the inner chamber 78 and the inner and outer annular chambers 82 and 85, the water in the inner and outer annular passageways 90a and 90b rises and is delivered into the upper portion 35 of the hollow interior region 6 of the storage tank 70 through the first outlet port 95. Water from the lower portion 30 of the hollow interior region 6 is drawn into the annular passageways 90 through the first inlet ports 93.

Returning now to the heating apparatus 72, the heating apparatus 72 comprises a housing 102 which comprises an elongated cylindrical wall 104 which defines a vertically extending passageway 105. A first inlet port 106 accommodates water from a lower portion 30 of the hollow interior region 6 into the passageway 105, and a first outlet port 107 extending from the passageway 105 towards the top thereof accommodates water from the passageway 105 to the upper portion 35 of the hollow interior region 6. The heating element 73 of the immersion heater 74 is located in the passageway 105 for heating water therein. A housing 108 of the immersion heater 74 extends through an opening 109 in the top wall 5 of the storage tank 70. The housing 102 is clad in heat insulating material 110 which is encased in a metal foil shell 111.

The operation of the heating apparatus 72 is substantially similar to the operation of the heating apparatus 51 of the storage tank 50. On powering up of the heating element 73, water in the passageway 105 is heated and rises through the passageway 105 and in turn through the first outlet port 107 to the upper portion 35 of the hollow interior region 6. Water in turn is drawn into the passageway 105 through the first inlet port 106 from the lower portion 30 of the hollow interior region 6. Thereafter, operation of the heating apparatus 71 and the heating apparatus 72 is similar to that described with reference to the storage tank 70 and the storage tank 50, respectively.

Referring now to Figs. 27 and 28, there is illustrated a portion of a water storage tank according to another embodiment of the invention, indicated generally by the reference numeral 120. The water storage tank 120 is substantially similar to the water storage tank 1 , and similar components are identified by the same reference numerals. In this embodiment of the invention heating apparatus, also according to the invention and indicated generally by the reference numeral 121 , is located in the hollow interior region 6 of the water storage tank 120. The heating apparatus 121 comprises a housing 122 comprising an inner cylindrical wall 123 and an outer cylindrical wall 124 spaced apart from and concentric with the inner cylindrical wall 123. An annular top wall 130 extends between the inner and outer cylindrical side walls 123 and 124.

A helical coil 125 comprising a tube 126 formed into a helix is located between the inner cylindrical wall 123 and the outer cylindrical wall 124. The tube 126 of the helical coil 125 defines a helical chamber 127 which extends through the coil 125 for accommodating heat exchange water from a boiler therethrough. The helical coil 125 sealably engages the inner and outer cylindrical walls 123 and 124 to form with the inner and outer side walls 123 and 124 a helical passageway 132 which extends between the inner and outer cylindrical walls 123 and 124 for accommodating water therethrough from the lower portion 30 of the hollow interior region 6 of the storage tank 120 to the upper portion 35 thereof.

A first inlet port 134 to the helical passageway 132 is formed between the inner and outer cylindrical walls 123 and 124 adjacent the lower end thereof for

accommodating water into the passageway 132 from the lower portion 30 of the hollow interior region 6. A first outlet port 135 extends from the annular top wall 130 which extends between the inner and outer cylindrical walls 123 and 124 for communicating the helical passageway 132 with the upper portion 35 of the hollow interior region 6 of the storage tank 120. The tube 126 of the helical coil 125 at the upper end thereof forms a second inlet port 136 to the helical chamber 127 of the helical coil 125 for accommodating heat exchange water into the helical chamber 127 from a boiler. The other end of the tube 126 of the helical coil 125 at the lower end of the housing 122 terminates in a second outlet port 137 for accommodating heat exchange water from the helical chamber 127 to be returned to the boiler. Inlet and outlet pipes 38 and 39, respectively, similar to the inlet and outlet pipes 38 and 39 of the storage tank 1 extend through the side wall 4 of the storage tank 120 for accommodating heat exchange water from the boiler to the helical chamber 127 of the helical coil 125 and for accommodating water from the helical chamber 127 of the helical coil 125 to the boiler, respectively.

Heat insulating material 140 completely dads the inner cylindrical wall 123, the outer cylindrical wall 124 and the top wall 130 of the housing 122. Inner and outer shells 141 and 142 as well as an annular top and a pair of annular bottom walls 144 and 145 retain the heat insulating material 144 sandwiched between the shells 141 , 142 and the walls 143, 144 and 145 and the inner and outer cylindrical walls 123, 124 and the annular top wall 130. Otherwise, the water storage tank 120 and its use is similar to that of the water storage tank 1. Heat exchange water passing through the helical chamber 127 of the helical coil 25 heats water in the helical passageway 132 which rises through the helical passageway 132 and exits through the first outlet port 135 and into the upper portion 35 of the hollow interior region 6 of the storage tank 120. Water from the lower portion 30 of the hollow interior region 6 is drawn into the helical passageway 132 through the first inlet port 134 as the heated water rises through the helical passageway 132.

Referring now to Figs. 29 and 30, there is illustrated a portion of a water storage tank according to another embodiment of the invention, indicated generally by the reference numeral 150. The water storage tank 150 is substantially similar to the water storage tank 120 and the water storage tank 1 , and similar components are identified by the same reference numerals. The only difference between the water storage tank 150 and the water storage tank 120 is in the heating apparatus 151. The heating apparatus 151 in this embodiment of the invention comprises a housing 152 which is partly formed by the side wall 4 of the storage tank 150 and an inner cylindrical side wall 153 which is spaced apart from the side wall 4 of the storage tank 150 and is concentric therewith. An annular top wall 154 extends from the inner side wall 153 adjacent the top thereof to the side wall 4 and defines with the side wall 4 a vertically extending annular passageway 155. A helical coil 157 which is similar to the helical coil 125 of the storage tank 120 is located in the passageway 155 but is spaced apart from the side wall 4 of the water tank 150 and from the inner cylindrical wall 153. Accordingly, the features and elements of the coil 157 are identified by similar reference numerals as those of the helical coil 125 of the storage tank 120. In this embodiment of the invention the inner cylindrical wall 153 at its lower end thereof defines with the side wall 4 of the storage tank 150 a first inlet port 134 similar to the first inlet port 134 of the heating apparatus 121. A first outlet port 135 similar to the first outlet port 135 of the storage tank 120 extends from the top wall 154 of the housing 152.

Heat insulating material 158 dads the inner cylindrical side wall 153 and the annular top wall 154 as well as the first outlet port 135. A shell 159 of metal foil material sandwiches the heat insulating material 158 between the shell 159 and the inner cylindrical side wall 153 and the annular top wall 154 and also sandwiches the insulating material 158 with the first outlet port 135.

In use, as the helical coil 157 is heated by heat exchange water from the boiler, water in the annular passageway 155 commences to rise upwardly in the annular passageway 155 and exits through the first outlet port 135 into the upper portion 135 of the hollow interior region 6 of the storage tank 150. As the water rises through the annular passageway 155, water is drawn into the annular passageway 155 through the first inlet port 134 from the lower portion 30 of the hollow interior region 6 of the storage tank 150. Otherwise, operation of the water storage tank 150 is similar to that of the storage tank 120.

Referring now to Figs. 31 and 32, there is illustrated a water storage tank according to a further embodiment of the invention, indicated generally by the reference numeral 170. The water storage tank 170 is substantially similar to the water storage tank 1 , and similar components are identified by the same reference numerals. However, in this embodiment of the invention the water storage tank 170 is of slightly different shape to that of the water storage tank 1 in that the diameter of the side wall 4 of the storage tank 170 is greater than the vertical height of the hollow interior region 6 of the storage tank 170, while in the storage tank 1 the diameter of the side wall 4 thereof is less than the overall height of the hollow interior region 6. Heating apparatus also according to the invention and indicated generally by the reference numeral 171 which is located in the hollow interior region 6 is similar to the heating apparatus 71 of the storage tank 70, and similar components are identified by the same reference numerals. The main difference between the heating apparatus 171 and the heating apparatus 71 of the water storage tank 70 is that the housing 75 of the heating apparatus 171 is inclined with the inner and outer annular passageways 90a and 90b, respectively inclined upwardly from the first inlet ports 93 to the first outlet port 95. In this embodiment of the invention the first inlet ports 93 communicate the inner and outer annular passageways 90a and 90b with a lower portion 30 of the hollow interior region 6 of the storage tank 170, and the first outlet port 95 communicates the inner and outer annular passageways 90a and 90b with the upper portion 35 of the hollow interior region 6 of the storage tank 170.

In this embodiment of the invention the heating apparatus 171 is particularly suitable for receiving heat exchange water from a solar panel. Otherwise, the water storage tank 170 is substantially similar to the water storage tank 1, and the heating apparatus 171 is similar to the heating apparatus 71 , and accordingly, use and operation of the water storage tank 170 and the heating apparatus 171 is similar to that of the water storage tank 1 and the heating apparatus 71.

Referring now to Figs. 33 to 35, there is illustrated a water storage tank according to another embodiment of the invention, indicated generally by the reference numeral 180. The storage tank 180 is somewhat similar to the storage tank 1 , and similar components are identified by the same reference numerals. However, in this embodiment of the invention the storage tank 180, while being cylindrical, is located with its central axis extending horizontally, rather than vertically. The tank 180 comprises a cylindrical side wall 181 which is closed by opposite end caps 182 and 183. A main water inlet 8 is provided in the end cap 182 at the lower end thereof, and the main water outlet 9 extends from the side wall 181 adjacent the top 184 thereof. Heating apparatus also according to the invention and indicated generally by the reference numeral 185 is located in a lower end 186 of the hollow interior region 6 of the tank 180. The heating apparatus 185 in this embodiment of the invention comprises a semi- cylindrical wall 187 which forms with a portion 188 of the side wall 4 a housing 189. One end of the housing 189 is closed by the end cap 183 of the tank 180, and an end wall 190 at the other end of the housing 189 closes the other end of the housing. The housing 189 defines a passageway 192 which extends through the housing 189 from the end wall 190 to the end cap 183 of the tank 180 for accommodating water to be heated therein.

A first inlet port 193 is formed in the end wall 190 for accommodating water from the hollow interior region 6 of the tank 180 into the passageway 192, and a first outlet port 194 extends upwardly from the semi-cylindrical wall 187 adjacent the top thereof and adjacent the end cap 181. The first outlet port 194 extends upwardly from the passageway 192 and terminates approximately 40mm from the side wall 181 adjacent the top 184 thereof for accommodating heated water from the passageway 192 into an upper portion 35 of the hollow interior region 6 of the tank 180.

A heating means, in this embodiment of the invention a heat exchanger 195 is located in the passageway 192 and extends substantially the length of the passageway 192 for accommodating heat exchange water for transferring heat into the water in the passageway 192. The heat exchanger 195 comprises an elongated tube 196 which is bent at 197 at one end of the passageway 192, and at 198 at the opposite end of the passageway 192 to form a plurality of longitudinally extending interconnected heat exchange tubes 199 for accommodating heat exchange water therethrough for heating the water in the passageway 192. The tube 196 terminates at one of its ends in a second inlet port 200 and at its other end in a second outlet port 201. Heat exchange water from a boiler or a solar panel is supplied to the heat exchange tube 196 through the second inlet port 200, and is returned to the boiler or a solar panel through the second outlet port 201. It has been found that the heating apparatus 185 is particularly suitable for receiving heat exchange water from a solar panel.

The semi-cylindrical wall 187 is encased in heat insulating material 203 which is covered by a metal foil shield 204. Heat insulating material 205 encases the tank 180, which is encased in a metal foil shield 206.

Use of the tank 180 is substantially similar to use of the tank 1. With heat exchange water circulating through the heat exchanger 191 from the second inlet port 200 to the second outlet port 201 from a solar panel, water in the passageway 192 is heated. The heated water from the passageway 192 rises through the first outlet port 194 and is delivered into the upper portion 35 of the hollow interior region 6 of the tank 180. As the water from the passageway 192 is being delivered through the first outlet port 194, water from the lower portion 30 of the hollow interior region 6 is drawn into the passageway 192 through the first inlet port 193 for heating in the passageway 192. Water is drawn off from the storage tank 180 through the main outlet port 9, and make-up water is delivered into the hollow interior region 6 through the main inlet port 8. Otherwise, the storage tank 180 and its operation is similar to that described with reference to the water storage tank 1.

It is envisaged that the heat exchanger 195 of the heating apparatus 185 may be provided with a plurality of transverse heat exchange fins formed by a plurality of transversely extending heat exchange plates through which the heat exchange tubes 199 would extend for further enhancing the transfer of heat from the heat exchange water to the water in the passageway 192. It is also envisaged that instead of providing the heat exchanger 195 as one continuous heat exchange tube 196, it is envisaged that in certain cases, a plurality of parallel spaced apart tubes could be provided which would extend between header tanks at respective opposite ends of the tubes.

While some of the water storage tanks have been described with only one heating apparatus, either a heating apparatus which comprises a heat exchanger, or a heating apparatus which comprises an immersion heater, it will be readily apparent to those skilled in the art that each of the water storage tanks may be provided with both a heating apparatus which comprises a heat exchanger and a separate heating apparatus which comprises an immersion heater. It will also be appreciated that in cases where the heating apparatus is provided with an immersion heater, and the immersion heater is relatively long, it is envisaged that the housing of the heating apparatus, and in turn the heating element of the immersion heater may be inclined rather than extending vertically or horizontally.

While the heating apparatus have been described as comprising passageways of particular shape and configuration, the passageways of the heating apparatus for accommodating water from the lower portion to the upper portion of the hollow interior region may be of any other suitable shape and configuration.

In general, the U-value of the heat insulating material which dads the housings of the heating apparatus and the heat insulating material which dads the water storage tank will typically be of a similar U-value, however, in certain cases, it is envisaged that the U-value of the heat insulating material cladding the housing of the heating apparatus may be different to that of the heat insulating material which dads the water storage tank, and may be greater or lesser than the U-value of the heat insulating material which dads the corresponding water storage tank.

While the water storage tanks have been described as being cylindrical tanks, the water storage tanks may be of any other suitable shape or construction.

It will also be appreciated that while the heat exchange medium has been described as being heat exchange water provided by an oil or gas fired boiler, a back boiler of an open fireplace or a stove, the heat exchange water may be provided by any other suitable source, and as described with reference to the heating apparatus 171 of the water storage tank 170, the heat exchange water may be provided from a solar panel or solar panels. Indeed, it is also envisaged that the heat exchange medium may be other than water, for example, steam or super-heated steam, or any other suitable heat exchange medium.

It is also envisaged that a dual system may be provided for facilitating providing heat exchange medium from a boiler or boilers and a solar panel or solar panels to the heating apparatus.

Claims

1. Heating apparatus adapted for locating in a water storage tank defining a hollow interior region for heating water in the hollow interior region of the storage tank, the heating apparatus comprising a housing adapted for mounting in the hollow interior region of the storage tank, at least one elongated passageway extending through the housing adapted to accommodate water through the housing from a lower portion of the hollow interior region of the storage tank to an upper portion thereof, a first inlet port to the at least one passageway adapted to communicate the passageway with the lower portion of the hollow interior region of the storage tank, a first outlet port from the at least one passageway adapted to communicate the passageway with the upper portion of the hollow interior region of the storage tank, and a heating means in the housing adapted to heat water in the at least one passageway, so that water heated in the passageway is urged by convection through the passageway to the upper portion of the hollow interior region of the storage tank through the first outlet port.

2. Heating apparatus as claimed in Claim 1 in which the heating means extends at least partly around the at least one passageway.

3. Heating apparatus as claimed in Claim 1 or 2 in which the heating means extends completely around the at least one passageway.

4. Heating apparatus as claimed in any preceding claim in which the heating means extends substantially the length of the at least one passageway.

5. Heating apparatus as claimed in any preceding claim in which the heating means comprises a heat exchanger.

6. Heating apparatus as claimed in Claim 5 in which the housing comprises a chamber of the heat exchanger adapted to accommodate a heat exchange medium, a second inlet port communicating with the chamber for accommodating the heat exchange medium to the chamber, and a second outlet port communicating with the chamber for accommodating the heat exchange medium from the chamber, the chamber co-operating with the at least one passageway for transferring heat from the heat exchange medium to water in the passageway.

7. Heating apparatus as claimed in Claim 6 in which the housing comprises at least one partition wall separating the at least one passageway from the chamber, the partition wall being of a heat conducting material and being adapted to transfer heat from the heat exchange medium to water in the passageway.

8. Heating apparatus as claimed in Claim 6 or 7 in which a plurality of passageways extend through the housing.

9. Heating apparatus as claimed in any of Claims 6 to 8 in which each passageway extends through the chamber, and one of the partition walls extends around each passageway to separate the corresponding passageway from the chamber.

10. Heating apparatus as claimed in any of Claims 6 to 9 in which the passageways are configured in an array, the array comprising one of the passageways being centrally located and a plurality of the passageways arranged along a pitch circle concentric with the central one of the passageways, the passageways arranged along the pitch circle being spaced apart from each other and spaced apart from the central one of the passageways.

11. Heating apparatus as claimed in Claim 10 in which a plurality of the passageways are arranged along a plurality of radially spaced apart pitch circles concentric with the central one of the passageways.

12. Heating apparatus as claimed in any preceding claim in which each passageway is of circular transverse cross-section.

13. Heating apparatus as claimed in any of Claims 6 to 12 in which at least two chambers are provided, the chambers defining the at least one passageway therebetween.

14. Heating apparatus as claimed in Claim 13 in which one of the chambers is of annular construction extending around the other one of the chambers, and defining with the said other one of the chambers the passageway as an annular passageway.

15. Heating apparatus as claimed in Claim 13 or 14 in which each of the chambers is of annular construction, one of the chambers extending around the other of the chambers and defining with the said other of the chambers one of the passageways as an annular passageway, the said other of the chambers defining another one of the passageways as a central passageway extending through the said other of the chambers.

16. Heating apparatus as claimed in any of Claims 6 to 15 in which a plurality of the chambers are provided, the chambers being of annular construction, each chamber extending around the next adjacent chamber, and defining with the next adjacent chamber the passageway as an annular passageway.

17. Heating apparatus as claimed in Claim 16 in which the chambers are concentric with each other and radially spaced apart from each other.

18. Heating apparatus as claimed in any preceding claim in which the chamber is configured as a helical chamber.

19. Heating apparatus as claimed in any preceding claim in which the at least one passageway is configured as a helical passageway.

20. Heating apparatus as claimed in any of Claims 5 to 19 in which the heat exchanger is adapted to receive heat exchange medium from a boiler.

21. Heating apparatus as claimed in any of Claims 6 to 20 in which the heat exchanger is adapted to receive heat exchange medium from a solar panel.

22. Heating apparatus as claimed in any of Claims 6 to 21 in which the heat exchange medium comprises water.

23. Heating apparatus as claimed in any preceding claim in which the housing comprises one passageway, and the heating means is located in the passageway.

24. Heating apparatus as claimed in Claim 23 in which the heating means comprises an electrically powered heating means.

25. Heating apparatus as claimed in Claim 23 or 24 in which the heating means comprises an electrically powered heating element encased in a heat transfer casing.

26. Heating apparatus as claimed in any of Claims 23 to 25 in which the heating means comprises an immersion heater.

27. Heating apparatus as claimed in any preceding claim in which the heating means extends substantially the length of the passageway.

28. Heating apparatus as claimed in any preceding claim in which the housing is adapted for mounting in the hollow interior region of the storage tank with the at least one passageway extending substantially vertically.

29. Heating apparatus as claimed in any of Claims 1 to 27 in which the housing is adapted for mounting in the hollow interior region of the storage tank with the at least one passageway extending substantially horizontally.

30. Heating apparatus as claimed in any of Claims 1 to 27 in which the housing is adapted for mounting in the hollow interior region of the storage tank with the at least one passageway extending in a general direction inclined to the horizontal.

31. Heating apparatus as claimed in any preceding claim in which the sum of the volumes of the one or more passageways is significantly less than the volume of the hollow interior region of the storage tank.

32. Heating apparatus as claimed in any preceding claim in which the sum of the volumes of the one or more passageways is not more than 10% of the volume of the hollow interior region of the tank.

33. Heating apparatus as claimed in any preceding claim in which the sum of the volumes of the one or more passageways is not more than 5% of the volume of the hollow interior region of the tank.

34. Heating apparatus as claimed in any preceding claim in which the sum of the volumes of the one or more passageways is not more than 1% of the volume of the hollow interior region of the tank.

35. Heating apparatus as claimed in any preceding claim in which the housing comprises an outer casing.

36. Heating apparatus as claimed in Claim 35 in which the outer casing comprises a base wall, a spaced apart top wall, and a side wall extending around the base wall and the top wall and extending from the base wall to the top wall.

37. Heating apparatus as claimed in Claim 36 in which the first inlet port is located in the base wall of the outer casing, and the first outlet port extends from the top wall of the outer casing.

38. Heating apparatus as claimed in any of Claims 1 to 36 in which the first inlet port is located in the side wall of the outer casing, and the first outlet port is located in the side wall of the outer casing.

39. Heating apparatus as claimed in any of Claims 36 to 38 in which the second inlet port and the second outlet port extend from the side wall of the outer casing.

40. Heating apparatus as claimed in any preceding claim in which the housing is clad in a heat insulating material.

41. Heating apparatus as claimed in any preceding claim in which the heating means and the passageway co-operate to form a thermosyphon in the passageway for urging water through the passageway from the first inlet port to the first outlet port.

42. A storage tank for storing water to be heated therein, the storage tank defining a hollow interior region having an upper portion and a lower portion, and a heating apparatus as claimed in any preceding claim located in the hollow interior region of the storage tank with the first inlet port adapted to communicate the first passageway with the lower portion of the hollow interior region of the storage tank for accommodating water from the lower portion of the hollow interior region of the storage tank into the at least one passageway, and the first outlet port being adapted to communicate the at least one passageway with the upper portion of the hollow interior region of the storage tank for accommodating water from the at least one passageway to the upper portion of the hollow interior region of the storage tank.

43. A storage tank as claimed in Claim 41 in which an inlet pipe extends through a wall of the storage tank to the second inlet port of the housing for accommodating heat exchange medium into the chamber of the heat exchanger, and an outlet pipe extends through the wall of the storage tank from the second outlet port for accommodating the heat exchange medium from the chamber of the heat exchanger.

44. A water storage tank defining a hollow interior region and comprising a lower main inlet port to the hollow interior region for accommodating water into the hollow interior region adjacent a lower portion thereof, an upper main outlet port from the hollow interior region for accommodating water from the hollow interior region adjacent an upper portion thereof, a heating apparatus mounted in the hollow interior region for heating water therein, the heating apparatus comprising a housing mounted in the hollow interior region of the storage tank, at least one elongated passageway extending through the housing adapted to accommodate water through the housing from the lower portion of the hollow interior region of the storage tank to the upper portion of the hollow interior region of the storage tank, a first inlet port to the at least one passageway communicating the passageway with the lower portion of the hollow interior region of the storage tank, a first outlet port from the at least one passageway communicating the passageway with the upper portion of the hollow interior region of the storage tank, and a heating means in the housing adapted to heat water in the at least one passageway, so that water heated in the passageway is urged by convection through the passageway to the upper portion of the hollow interior region of the storage tank through the first outlet port.

45. A water storage tank as claimed in Claim 44 in which the heating apparatus is located in an intermediate portion of the hollow interior region of the storage tank between the lower portion of the hollow interior region and the upper portion thereof.

46. A water storage tank as claimed in Claim 44 or 45 in which the heating means extends at least partly around the at least one passageway.

47. A water storage tank as claimed in any of Claims 44 to 46 in which the heating means extends completely around the at least one passageway.

48. A water storage tank as claimed in any of Claims 44 to 47 in which the heating means extends substantially the length of the at least one passageway.

49. A water storage tank as claimed in any of Claims 44 to 48 in which the heating means comprises a heat exchanger.

50. A water storage tank as claimed in Claim 49 in which the housing comprises a chamber of the heat exchanger adapted to accommodate a heat exchange medium, a second inlet port communicating with the chamber for accommodating the heat exchange medium to the chamber, and a second outlet port communicating with the chamber for accommodating the heat exchange medium from the chamber, the chamber co-operating with the at least one passageway for transferring heat from the heat exchange medium to water in the passageway.

51. A water storage tank as claimed in Claim 50 in which the housing comprises at least one partition wall separating the at least one passageway from the chamber, the partition wall being of a heat conducting material and being adapted to transfer heat from the heat exchange medium to water in the passageway.

52. A water storage tank as claimed in Claim 50 or 51 in which a plurality of passageways extend through the housing.

53. A water storage tank as claimed in any of Claims 50 to 52 in which each passageway extends through the chamber, and one of the partition walls extends around each passageway to separate the corresponding passageway from the chamber.

54. A water storage tank as claimed in any of Claims 50 to 53 in which the passageways are configured in an array, the array comprising one of the

passageways being centrally located and a plurality of the passageways arranged along a pitch circle concentric with the central one of the passageways, the passageways arranged along the pitch circle being spaced apart from each other and spaced apart from the central one of the passageways.

55. A water storage tank as claimed in Claim 54 in which a plurality of the passageways are arranged along a plurality of radially spaced apart pitch circles concentric with the central one of the passageways.

56. A water storage tank as claimed in any of Claims 50 to 55 in which each passageway is of circular transverse cross-section.

57. A water storage tank as claimed in any of Claims 50 to 56 in which at least two chambers are provided, the chambers defining the at least one passageway therebetween.

58. A water storage tank as claimed in Claim 57 in which one of the chambers is of annular construction extending around the other one of the chambers, and defining with the said other one of the chambers the passageway as an annular passageway.

59. A water storage tank as claimed in Claim 57 or 58 in which each of the chambers is of annular construction, one of the chambers extending around the other of the chambers and defining with the said other of the chambers one of the passageways as an annular passageway, the said other of the chambers defining another one of the passageways as a central passageway extending through the said other of the chambers.

60. A water storage tank as claimed in any of Claims 57 to 59 in which a plurality of the chambers are provided, the chambers being of annular construction, each chamber extending around the next adjacent chamber, and defining with the next adjacent chamber the passageway as an annular passageway.

61. A water storage tank as claimed in Claim 60 in which the chambers are concentric with each other and radially spaced apart from each other.

62. A water storage tank as claimed in any of Claims 44 to 61 in which the chamber is configured as a helical chamber.

63. A water storage tank as claimed in any of Claims 44 to 62 in which the at least one passageway is configured as a helical passageway.

64. A water storage tank as claimed in any of Claims 53 to 63 in which the heat exchanger is adapted to receive heat exchange medium from a boiler.

65. A water storage tank as claimed in any of Claims 53 to 64 in which the heat exchanger is adapted to receive heat exchange medium from a solar panel.

66. A water storage tank as claimed in any of Claims 53 to 65 in which the heat exchange medium comprises water.

67. A water storage tank as claimed in any of Claims 44 to 66 in which the housing comprises one passageway, and the heating means is located in the passageway.

68. A water storage tank as claimed in Claim 67 in which the heating means comprises an electrically powered heating means.

69. A water storage tank as claimed in Claim 67 or 68 in which the heating means comprises an electrically powered heating element encased in a heat transfer casing.

70. A water storage tank as claimed in any of Claims 67 to 69 in which the heating means comprises an immersion heater.

71. A water storage tank as claimed in any of Claims 44 to 70 in which the heating means extends substantially the length of the passageway.

72. A water storage tank as claimed in any of Claims 44 to 71 in which the housing is mounted in the hollow interior region of the storage tank with the at least one passageway extending substantially vertically.

73. A water storage tank as claimed in any of Claims 44 to 71 in which the housing is mounted in the hollow interior region of the storage tank with the at least one passageway extending substantially horizontally.

74. A water storage tank as claimed in any of Claims 44 to 71 in which the housing is mounted in the hollow interior region of the storage tank with the at least one passageway extending in a general direction inclined to the horizontal.

75. A water storage tank as claimed in any of Claims 44 to 74 in which the sum of the volumes of the one or more passageways is significantly less than the volume of the hollow interior region of the storage tank.

76. A water storage tank as claimed in any of Claims 44 to 75 in which the sum of the volumes of the one or more passageways is not more than 10% of the volume of the hollow interior region of the tank.

77. A water storage tank as claimed in any of Claims 44 to 76 in which the sum of the volumes of the one or more passageways is not more than 5% of the volume of the hollow interior region of the tank.

78. A water storage tank as claimed in any of Claims 44 to 76 in which the sum of the volumes of the one or more passageways is not more than 1 % of the volume of the hollow interior region of the tank.

79. A water storage tank as claimed in any of Claims 44 to 78 in which the housing comprises an outer casing.

80. A water storage tank as claimed in any of Claims 44 to 79 in which the outer casing comprises a base wall, a spaced apart top wall, and a side wall extending around the base wall and the top wall and extending from the base wall to the top wall.

81. A water storage tank as claimed in Claim 80 in which the first inlet port is located in the base wall of the outer casing, and the first outlet port extends from the top wall of the outer casing.

82. A water storage tank as claimed in Claim 80 or 81 in which the first inlet port is located in the side wall of the outer casing, and the first outlet port is located in the side wall of the outer casing.

83. A water storage tank as claimed in any of Claims 80 to 82 in which the second inlet port and the second outlet port extend from the side wall of the outer casing.

84. A water storage tank as claimed in any of Claims 44 to 83 in which the housing is clad in a heat insulating material.

85. A water storage tank as claimed in any of Claims 44 to 84 in which the heating means and the passageway co-operate to form a thermosyphon in the passageway for urging water through the passageway from the first inlet port to the first outlet port.

86. A water storage tank as claimed in any of Claims 44 to 85 in which the first outlet port extending from the heating apparatus terminates at a level in the hollow interior region of the storage tank a vertical distance below the level of the main outlet port from the hollow interior region of not more than 15% of the vertical height of the hollow interior region of the storage tank.

87. A water storage tank as claimed in any of Claims 44 to 86 in which the first outlet port extending from the heating apparatus terminates at a level in the hollow interior region of the storage tank a vertical distance below the level of the main outlet port from the hollow interior region of not more than 10% of the vertical height of the hollow interior region of the storage tank.

88. A water storage tank as claimed in any of Claims 44 to 87 in which the first outlet port extending from the heating apparatus terminates at a level in the hollow interior region of the storage tank a vertical distance below the level of the main outlet port from the hollow interior region of not more than 5% of the vertical height of the hollow interior region of the storage tank.

89. A water storage tank as claimed in any of Claims 44 to 88 in which the upper portion of the hollow interior region of the storage tank is defined between the main outlet port and the first outlet port.

90. A water storage tank as claimed in any of Claims 44 to 89 in which the first inlet port to the heating apparatus is at a level spaced apart a vertical distance above the level of the main inlet port of not more than 15% of the vertical height of the hollow interior region of the storage tank.

91. A water storage tank as claimed in any of Claims 44 to 90 in which the first inlet port to the heating apparatus is at a level spaced apart a vertical distance above the level of the main inlet port of not more than 10% of the vertical height of the hollow interior region of the storage tank.

92. A water storage tank as claimed in any of Claims 44 to 91 in which the first inlet port to the heating apparatus is at a level spaced apart a vertical distance above the level of the main inlet port of not more than 5% of the vertical height of the hollow interior region of the storage tank.

93. A water storage tank as claimed in any of Claims 44 to 92 in which the lower portion of the hollow interior region of the storage tank is defined between the first inlet port and a base of the water storage tank.

94. A water storage tank as claimed in any of Claims 44 to 93 in which the hollow interior region of the storage tank is of circular transverse cross-section, and comprises a base and a top wall which are circular when viewed in plan.

95. A water storage tank as claimed in Claim 94 in which the top wall is of domed shape, and the main outlet port extends substantially centrally from the top wall.

96. Apparatus as claimed in any of Claims 44 to 95 in which the storage tank is externally clad with a heat insulating material.

97. A water storage tank as claimed in any of Claims 44 to 96 in which two heating apparatus are located in the hollow interior region of the storage tank, one of the heating apparatus comprising a heating means located in the passageway of the housing of the heating apparatus, and the other heating apparatus comprising the heat exchanger.

98. A method for heating water in a water storage tank which defines a hollow interior region for the water, providing a heating apparatus in the hollow interior region, wherein the heating apparatus comprises a housing, at least one elongated passageway extending through the housing adapted to accommodate water therethrough and terminating at one end in a first inlet port and at another end in a first outlet port, and a heating means in the housing adapted to heat water in the at least one passageway, locating the heating apparatus in the hollow interior region of the storage tank with the first inlet port located adjacent a lower portion of the hollow interior region, and the first outlet port located adjacent an upper portion of the hollow interior region, so that water in the at least one passageway is heated by the heating means and is urged by convection through the passageway to the upper portion of the hollow interior region of the storage tank through the first outlet port.

99. A method as claimed in Claim 98 in which the heating means extends at least partly around the at least one passageway.

100. A method as claimed in Claim 98 or 99 in which the heating means extends completely around the at least one passageway.

101. A method as claimed in any of Claims 98 to 100 in which the heating means extends substantially the length of the at least one passageway.

102. A method as claimed in any of Claims 98 to 101 in which the heating means comprises a heat exchanger.

103. A method as claimed in Claim 102 in which the housing comprises a chamber of the heat exchanger adapted to accommodate a heat exchange medium, a second inlet port communicating with the chamber for accommodating the heat exchange medium to the chamber, and a second outlet port communicating with the chamber for accommodating the heat exchange medium from the chamber, the chamber co-operating with the at least one passageway for transferring heat from the heat exchange medium to water in the passageway.

104. A method as claimed in Claim 103 in which the housing comprises a chamber of the heat exchanger adapted to accommodate a heat exchange medium, a second inlet port communicating with the chamber for accommodating the heat exchange medium to the chamber, and a second outlet port communicating with the chamber for accommodating the heat exchange medium from the chamber, the chamber co-operating with the at least one passageway for transferring heat from the heat exchange medium to water in the passageway.

105. A method as claimed in Claim 103 or 104 in which a plurality of passageways extend through the housing.

106. A method as claimed in any of Claims 103 to 105 in which each passageway extends through the chamber, and one of the partition walls extends around each passageway to separate the corresponding passageway from the chamber.

107. A method as claimed in any of Claims 103 to 106 in which the passageways are configured in an array, the array comprising one of the passageways being centrally located to comprise one central passageway and a plurality of the passageways arranged along a pitch circle concentric with the central one of the passageways, the passageways arranged along the pitch circle being spaced apart from each other and spaced apart from the central one of the passageways.

108. A method as claimed in any of Claims 107 in which a plurality of the passageways are arranged along a plurality of radially spaced apart pitch circles concentric with the central one of the passageways.

109. A method as claimed in any of Claims 98 to 108 in which each passageway is of circular transverse cross-section.

110. A method as claimed in any of Claims 103 to 109 in which at least two chambers are provided, the chambers defining the at least one passageway therebetween.

111. A method as claimed in Claim 110 in which one of the chambers is of annular construction extending around the other one of the chambers, and defining with the said other one of the chambers the passageway as an annular passageway.

112. A method as claimed in Claim 110 or 111 in which each of the chambers is of annular construction, one of the chambers extending around the other of the chambers and defining with the said other of the chambers one of the passageways as an annular passageway, the said other of the chambers defining the passageway as a central passageway extending through the said other of the chambers.

113. A method as claimed in any of Claims 103 to 112 in which a plurality of the chambers are provided, the chambers being of annular construction, each chamber extending around the next adjacent chamber, and defining with the next adjacent chamber the passageway as an annular passageway.

114. A method as claimed in Claim 113 in which the chambers are concentric with each other and radially spaced apart from each other.

115. A method as claimed in any of Claims 98 to 114 in which the chamber is configured as a helical chamber.

116. A method as claimed in any of Claims 98 to 115 in which the at least one passageway is configured as a helical passageway.

117. A method as claimed in any of Claims 98 to 116 in which the heat exchanger is adapted to receive heat exchange medium from a boiler.

118. A method as claimed in any of Claims 98 to 117 in which the heat exchanger is adapted to receive heat exchange medium from a solar panel.

119. A method as claimed in any of Claims 98 to 118 in which the heat exchange medium comprises water.

120. A method as claimed in any of Claims 98 to 119 in which the housing comprises one passageway, and the heating means is located in the passageway.

121. A method as claimed in Claim 120 in which the heating means comprises an electrically powered heating means.

122. A method as claimed in Claim 120 or 121 in which the heating means comprises an electrically powered heating element encased in a heat transfer casing.

123. A method as claimed in any of Claims 120 to 122 in which the heating means comprises an immersion heater.

124. A method as claimed in any of Claims 120 to 123 in which the heating means extends substantially the length of the passageway.

125. A method as claimed in any of Claims 98 to 124 in which the housing is adapted for mounting in the hollow interior region of the storage tank with the at least one passageway extending substantially vertically.

126. A method as claimed in any of Claims 98 to 124 in which the housing is adapted for mounting in the hollow interior region of the storage tank with the at least one passageway extending substantially horizontally.

127. A method as claimed in any of Claims 98 to 124 in which the housing is adapted for mounting in the hollow interior region of the storage tank with the at least one passageway extending in a general direction inclined to the horizontal.

128. A method as claimed in any of Claims 98 to 127 in which the sum of the volumes of the one or more of the passageways is significantly less than the volume of the hollow interior region of the storage tank.

129. A method as claimed in any of Claims 98 to 128 in which the sum of the volumes of the one or more passageways is not more than 10% of the volume of the hollow interior region of the tank.

130. A method as claimed in any of Claims 98 to 129 in which the sum of the volumes of the one or more passageways is not more than 5% of the volume of the hollow interior region of the tank.

131. A method as claimed in any of Claims 98 to 130 in which the sum of the volumes of the one or more passageways is not more than 1% of the volume of the hollow interior region of the tank.

132. A method as claimed in any of Claims 98 to 131 in which the housing comprises an outer casing.

133. A method as claimed in Claim 132 in which the outer casing comprises a base wall, a spaced apart top wall, and a side wall extending around the base wall and the top wall and extending from the base wall to the top wall.

134. A method as claimed in Claim 133 in which the first inlet port is located in the base wall of the outer casing, and the first outlet port extends from the top wall of the outer casing.

135. A method as claimed in Claim 133 or 134 in which the first inlet port is located in the side wall of the outer casing, and the first outlet port is located in the side wall of the outer casing opposite the first inlet port.

136. A method as claimed in any of Claims 133 to 135 in which the second inlet port and the second outlet port extend from the side wall of the outer casing.

137. A method as claimed in any of Claims 98 to 136 in which the housing is clad in a heat insulating material.

138. A method as claimed in any of Claims 98 to 137 in which the heating means and the passageway co-operate to form a thermosyphon in the passageway for urging water through the passageway from the first inlet port to the first outlet port.