GB2350415A - Instantaneous water heater with baffles - Google Patents

Abstract

An instantaneous water heater for a shower comprises a cylindrical vessel 200 with an inlet 203, an outlet 212 and a plurality of baffles 301-304 to generate turbulent flow and deflect the water flow through the vessel into contact with the heated wall. The wall may be heated by a conventional electrical element wound in a spiral round the vessel, or preferably by thick film electrical heating elements (208,209 Fig 2). The wall consists of a metal eg stainless steel cylinder with an outer coating of dielectric material to which the sheet heating elements (208, 209) are attached. The baffles have a central tube (600, Fig 6), which interlocks with adjacent baffles to surround a passage to the outlet 212, and four spaced apertures (602) with cup-shaped deflectors which direct the water radially outwardly. The baffles provide efficient water mixing and heat exchange at the vessel wall whilst reducing scale deposition.

Description

2350415

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIA

IMPROVED SHOWER HEATER Field of the Invention

The present invention relates to a means and method of producing a S turbulent fluid flow in a fluid heating device, and particularly, although not exclusively, to a heater device for a domestic shower unit, arranged to create a turbulent fluid flow against a thick film technology heating element, and a shower unit incorporating such a heater device.

Background to the Invention

In order to heat water in both domestic and industrial sanitary applications, it is known in the prior art to use coil heating elements consisting of a heating wire surrounded by an insulating compound within a copper (or other metal) tube. Such conventional elements are placed centrally within a chamber, so as to allow is water to flow over the element and be heated. Such elements retain heat for long periods following disconnection of power due to the large mass of the element components giving the elements a high thermal inertia. Accordingly, when considering known domestic electric shower heaters of the type, including coil heating elements, there is a problem that a high temperature discharge is likely when the unit is activated soon after a previous operation. This is because the water remaining in the heating chamber between operations is super-heated by the slowly cooling element.

Heating element technological advances in the fields of domestic consumer products have seen introduction of 1hick film technology". This comprises a high electrical resistance ink compound applied to a surface used as a heating element. The ink compound is typically of the order of thickness of 0.1 mm, hence due to a low mass, when the appliance is disconnected, virtually no residual heat remains in the element. This means that water remaining adjacent to a thick film technology type element following the end of element operation will not become P440.spec DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL super-heated. To date, thick film technology has been successfully applied to flat sheet heating elements for use in domestic kettles.

The inventors have conducted private research into mechanisms by which super heated water discharges occurring on activation of the electric shower unit can be avoided. As part of the research towards the present invention, water heating in electric shower units has been considered. Although still at a research stage, it is anticipated that thick film technology could provide a user friendly heat protection mechanism when the shower unit is activated, by removing the possibility of high temperature water discharges immediately following unit activation. This would be of commercial value due to the inherent safety aspect and user friendly temperature reliability.

The inventors have recognized that thick film technology known to be incorporated in flat sheet elements, eg for use in kettles has potential for use in flat can heating elements suitable for slim line shower units. Such slim-line units are envisaged to reduce the bulkiness of many electric shower units, lending to increasingly aesthetically appealing design options.

Summaj)t of the Invention One object of the specific embodiment of the present invention is to provide a water heater device which gives a uniform and predictable water temperature through instantaneous heating of water.

Another object of the specific embodiments of the present invention is to provide a high reliability, low maintenance heater device for a shower unit, which avoids high temperature water discharges immediately after activation of the heating device.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

Specific methods according to the present invention aim to provide a method of forcing water under pressure to interior wall surfaces of a water containing vessel and producing a turbulent flow of water at said vessel wall surface.

In particular, the specific methods according to the present invention aim to reduce scale deposition within a heating vessel by forming a nonlaminar water flow removing the presence and formation of 'dead zones' of water flow at the vessel walls or elsewhere in the vessel. Such methods may lead to a prolonged 10 element lifespan.

Specific embodiments according to the present invention provide means for the formation of turbulent flow at the walls of a cylindrical heating element tube aimed to achieve uniform fluid mixing and heating.

Specific embodiments and methods according to the present invention aim to provide a distribution and flow of water to facilitate water heating within a tubular container or vessel, where the vessel wail is part of the heating element, whilst minimizing deposition of scale.

The specific embodiments, recognize a capacity to change the direction of fluid flow and to convert a laminar flow to a turbulent flow by directing fluid flow radially outwards in several directions against a surface or surfaces.

Particularly, a shower unit comprising a water heating tube may utilize a means and method of efficient water mixing and heating.

Particularly, in the best mode implementation said water heating element includes elements incorporating thick film technology.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

According to a first aspect of the present invention there is provided a water heating device, said device comprising:

a vessel having an inlet for ingress of water and an outlet for egress of S water; and deflection means situated internal of said vessel, said deflection means operable in use to deflect a flow of said water through said vessel between said inlet and said outlet such as to cause a substantially turbulent flow of said water 10 within said vessel.

Preferably the vessel comprises a wall surrounding a water chamber, the wall comprising a plurality of electrical heating elements.

is Preferably the heating device is heated by a plurality of electrical heating elements.

Preferably the heating device comprises electrical heating elements which are soldered or welded or braised to said vessel wall.

Preferably the vessel wall comprises an inner wall surrounding said chamber; an electrically insulating outer layer adjacent to said inner wall; and a plurality of sheet heating elements adjacent to said insulating layer.

Suitably, a thermostat device is attached directly to the vessel wall.

Preferably, the water heating vessel is substantially cylindrical in construction.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

The water heating device preferably comprises a deflection means for producing turbulent water flow at the vessel wall or walls or anywhere in the vessel.

The water heating device preferably comprises a deflection means for directing water flow against a surface or surfaces and/or said vessel wall.

The water heating device preferably comprises deflection means for causing water flow substantially against and/or adjacent to said vessel wall.

Preferably the deflection means comprises a plurality of baffle plates arranged internally of said vessel, said baffle plates arranged in use, to direct a said flow of water in a direction transverse to a main internal surface of said vessel.

Suitably, said inlet is arranged to input water to said vessel at a first end of said vessel, and said outlet is arranged to outlet said water at a second end of said vessel, such that to pass between said inlet and said outlet, a said flow of water must encounter said plurality of baffle plates within said vessel.

Preferably the deflection means comprises a plurality of baffle plates, each said baffle plate comprising at least one aperture, wherein said baffle plates are arranged sequentially within said vessel between said inlet and said outlet, such that in use, a said water flow passing between said inlet and said outlet must encounter each of said plurality of baffle plates, wherein said apertures of said baffle plates are offset with respect to each other such that in order to pass through said plurality of apertures said water must follow a plurality of directions of flow between said inlet and outlet.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

Preferably the deflection means comprises at least one baffle plate comprising a plate member extending across said vessel in a direction transverse to the main central axis of said vessel, said plate member having at least one aperture, and at least one flow deflector means positioned immediately adjacent said aperture for changing a direction of flow of water passing through said aperture.

A said flow deflector means preferably comprises a substantially cupshaped member having a first portion extending in a direction transverse to a main plane of said baffle plate and a second portion extending in a plane substantially parallel to said main plane of said baffle plate.

The vessel preferably comprises a substantially cylindrical tubular outer wall a first substantially planar end plate, closing off a first end of said substantially cylindrical tubular wall and a second substantially planar end plate closing off a second end of said substantially cylindrical tubular wall.

The deflection means may comprise a plurality of baffle plates, each extending across said vessel in a direction transverse to the main central axis of said vessel, between said inlet and said outlet, wherein said plurality of baffle plates define a plurality of internal chambers, said chambers configured such that water passing between said inlet and said outlet must pass through said vessel from chamber to chamber and past said plurality of baffle plates.

The deflection means may comprise a plurality of baffle plates, each extending across said vessel in a direction transverse to the main central axis of said vessel, between said inlet and said outlet, wherein said plurality of baffle plates are arranged sequentially along a main central axis of said vessel, said baffle plates each extending transverse to said DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL main central axis and spaced apart from each other to define a plurality of chambers there between, wherein said plurality of baffle plates are assembled such as to define a water passage for outlet of water, said water passage comprising said outlet, wherein a primary direction of flow of water between said inlet and said outlet is in a first direction, and water flowing through said water passage flows in a second direction, said second direction opposite to said first direction.

According to a second aspect of the present invention there is provided a water heating device, said water heating device comprising:

a substantially cylindrical tubular vessel, said tubular vessel comprising a wall having an inner layer surrounding a chamber formed therein; is a layer of thermally conductive and electrically insulating material disposed externally of said inner layer; and a plurality of sheet heating elements dispose d externally on said electrically 20 insulating thermally conductive layer, wherein by applying an electrical current to said plurality of heating elements, said heating elements operate to heat said inner layer in a said thermally conductive layer, such that said inner layer is capable of heating a 25 volume of water contained within said chamber.

According to a first specific method of the present invention, there is provided a method of deflecting a flow of water through a vessel.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

Preferably, the method of flow deflection comprises converting a laminar flow to a turbulent flow.

Preferably the method of flow deflection comprises the steps of causing a water to flow substantially against and/or substantially adjacent to said vessel wall.

Preferably, said method of flow deflection produces turbulent water flow at said vessel wall or walls or anywhere in said vessels.

Preferably, said method of flow deflection directs a water flow against a surface of surfaces and/or said vessel wall.

Said method preferably directs a flow of water in a direction transverse to a 15 main internal surface of said vessel.

Preferably, the method of flow deflection deflects water through a plurality of directions of flow between a vessel inlet and a vessel outlet.

Preferably, said method of flow deflection provides for heating of said water by heat exchange at said vessel wall or walls or anywhere in said vessel.

According to a second specific method of the present invention, there is provided a method of heating a vessel wall or walls using one or a plurality of electrical heating elements attached to or part of said vessel wall or walls.

Preferably, the invention includes a shower unit comprising a water heating device according to any of the above aspects and methods.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL -g- Preferably, a water heating device for use in heating water according to any of the above aspects and methods.

The invention includes an improved water distributor comprising; one or more water distribution units; a central copper tube; base plate including inlet and outlet piping; top plate; top and base plate seals.

The invention includes one or more individual water distribution units where each unit comprises a hollow central cylindrical support extending vertically upwards and downwards from a centrally located circular baffle plate radiating horizontally throughout 3600 from and perpendicularly opposed to said central support one or more, but typically four baffles; wherein said baffle plate extends horizontally to leave only a fine space between the edge of the baffle plate and the water containing cylinder, when the water distributor is placed in an appropriate thick film technology heating element cylinder.

The invention includes one or more individual water distribution units wherein each unit contains one or more baffles, each baffle comprising; a raised circular platform, with a segment removed, such that the edge farthest from said central support is flattened and the cross sectional area of the DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIA circle is restricted to approximately 213rds compared to that predicted by its radius; said platform is supported by a curved plastic wall, supporting the platform S at all its curved edges; said platform support raises said platform above an aperture in the baffle plate.

The invention includes a means of interlocking adjacent individual water distribution units when the central support is placed around a copper tube such that any number of water distribution units may be incorporated.

Preferably, all baffles on one distribution unit are distributed evenly on the upper surface of the baffle plate throughout 3600 i.e. considering four baffles, each baffle is circumferentially 9W apart. Preferably, said baffle provides a fluid flow direction on the upper baffle plate surface radially outwards from the baffle plate center, such that fluid will impact on a surrounding cylinder at an angle of 900 to the point of impact. Preferably, said adjacent individual water distribution units separate and form vertically adjacent chambers, the only possible routes of fluid flow between chambers being provided by the baffle plate apertures and adjacent baffles or around the edge of the baffle plate forming the top and bottom chamber walls.

Preferably, said adjacent water distribution units interlock such as to provide a 45 circular change in baffle orientation about the baffle plate relative to vertically adjacent individual water distribution units.

Specific methods according to the present invention described herein are concerned with the formation of a turbulent fluid flow at any or all regions of the DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL wall of a cylindrical fluid containing vessel. Particularly, where said cylindrical vessel is designed to incorporate a form of heating element in/on the vessel walls.

Brief Description of the Drawings

For a better understanding of the invention and to show how the same may be carded into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which:

Fig. 1 illustrates an electric shower unit incorporating a heater device according to a first specific embodiment of the present invention, the shower unit comprising an inlet and an outlet pipe, and attached shower head, a heater can and a water distribution unit, a control panel, and a power supply; Fig. 2 illustrates schematically in external perspective view, the heater can device according to the first specific embodiment of the present invention; Fig. 3 illustrates a three dimensional view of the water distribution device assembly, with heater ran removed, comprising four individual water distribution units, each with four baffles mounted on a baffle plate with central support, base plate incorporates inlet and outlet pipes, top plate forces water into the central support pipe, leading to the outlet pipe; Fig. 4 illustrates a longitudinal section view of the water distribution device within the heater can, according to the first specific embodiment of the present invention wherein arrows indicate water flow routes through the device according to a first specific method; DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

Fig. 5 illustrates a three dimensional view of a water distribution device comprising four individual water distribution units without top plate, showing overflow water collection point and base plate water inlet aperture, and base plate peripheral apertures.

Fig. 6 illustrates a single individual water distribution unit, the central support can connect to identical units to build up a multi-unit column, three baffles are visible above baffle plate apertures; Fig. 7 illustrates the fluid flow velocity of a fluid flowing within a cylindrical vessel; and Fig. 8 illustrates a single baffle located on a baffle plate of an individual water distribution unit, arrows indicate deflected water flow routes.

Detailed Description of the Best Mode for CariVing Out the Invention

There will now be described by way of example the best mode contemplated by the inventors for carrying out the invention. In the following description numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent however, to one skilled in the art, that the present invention may be practised without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the present invention.

The inventors have foreseen that thick film technology may have a useful application in electric shower units for domestic or industrial application. In order to produce a slimline, compact shower unit, there is a requirement for a compact shower heating unit. The inventors have considered many shapes for shower heating units, incorporating flat thin film technology heating elements. However, DRAFT PATENT SPECIFICATION COMMERCIAL CONFIDENTIA in an instantaneous shower unit, internal water pressures of up to 10 bar must be accommodated. This introduces the problem that any water heating device must be capable of withstanding internal pressures of this magnitude, but in a manner which is cost effective and commercially reproduced.

The inventor's research indicates that thick film technology applied to stainless steel cylindrical heating vessels is one possible solution.

This introduces the further problems concerned with water distribution within the heating chamber and rate of fluid flow at the heat exchanging surface. Both factors are of importance to give efficient mixing and uniform water heating which is required to produce a constant temperature of water flow through the shower head.

Specific embodiments according to the present invention herein consider tubular water heating units where the tube wall forms a heat exchanging surface and a means and method of distributing water within such tubular heating units to mix and heat water entering such tubular heating units. This is achieved by the conversion of a laminar flow to a turbulent flow by directing fluid flow within the heating units radially outwards in several directions against the wall of the heating unit.

In particular, these embodiments are related to the use of cylindrical and/or tubular water heating units designed for use in electric shower units. Tubular heating units are predicted to withstand the required water pressures, in the region of 10 bar, commonly present in domestic electric shower units.

Fig. 1 herein illustrates an electric shower unit 100, comprising: a chassis 101 adapted for mounting to a wall or the like; an inlet pipe for cold water 102; an outlet pipe for mixed and heated water 103; a shower head 104; a power supply DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

105; a set of controls relating to temperature and pressure 106; a water heating can 107 comprising a tubular water heating element 108; base plate 109 and a top plate 110 the heating element enclosing a water distribution unit 111 with central copper tube 112 forming a central passage through the water distribution unit 103 connecting an outlet aperture at one end of the copper tube, and within the can, to the outlet pipe 103.

Referring to Fig. 2, herein, there is illustrated schematically in perspective external view, the water heating can 107 of the shower unit 100 of Fig. 1 herein.

The water heating can comprises: a substantially cylindrical tubular outer wall 200; at an upper end of the outer wall 200, a substantially circular top plate 201, closing off an upper end of the tubular outer wall; at a lower end of the outer wall, a base plate 202 closing off a lower end of the tubular outer wall, the base plate having an inlet pipe 203 comprising an elbow shaped tubular body adapted for, in use inputting water from a direction transverse to a main axis of said substantially cylindrical tubular outer wall, and having an outlet pipe 212 configured for outletting water from said water heating can in a direction substantially axially to said substantially cylindrical tubular outer wall 200, said outer wall 200, said top plate 201 and said base plate 202 forming an internal water tight chamber, through which water may pass, entered by said inlet pipe 203 and exited by said outlet pipe 202.

Top plate 201 and base plate 202 are each provided with a plurality of location apertures extending peripherally around said top plate and said base plate, corresponding respective ones of said apertures on said top plate and base plate respectively, aligning opposite each other and above and below said outer wall casing 200, such that a plurality of tension rods 204, 205, 206 extending substantially parallel to each other, and extending through said apertures on said top plate and said base plate are provided such as to tighten said top plate and base plate towards each other, with said substantially DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL cylindrical outer wall casing 200 being held there between. An amount of tension between the top plate 201 and the base plate 202 can be adjusted by tightening a plurality of threaded nuts 207, threaded onto ends of said tension rods 204-206 for tightening said top plate and said base plate to the cylindrical wall casing 200.

The cylindrical wall casing 200 comprises a tubular cylindrical wall of high thermal conductivity material, e.g. a hollow metal cylinder for example of stainless steel, an inner surface of which, in use, is in direct contact with water inside the chamber, the high thermal conductivity metal cylinder being coated with an outer layer of high electrical dielectric material, said layer of dielectric material being bonded to said high thermal conductivity cylinder; and a plurality of sheet heating elements 208, 209 each said sheet heating element comprising a high electrical resistivity sheet material which, upon application of an electrical current, becomes hot. The sheet heating elements are spaced apart from the inner high thermal conductivity cylinder, by the cylindrical outer layer of dielectric material, which is preferably of high thermal conductivity, but low electrical conductivity (i.e. electrically insulating). Each heating element is provided with a soldered or otherwise physically bonded electrical connection cable 210, 211. A thermostatic control device 212 is provided in direct physical and thermal contact with the dielectric layer to enable automatic cut-off of electrical power supply to the heating elements, if the temperature of the internal cylinder and/or dielectric layer rises above a pre-set value.

Referring to Figs. 3, 4, 5 and 6 herein there is illustrated schematically the water canister 107 in cutaway view. Water heating canister 107 comprises a water distribution device, as illustrated in Figs. 3, 4 and 5 designed to insert into a cylindrical water containing vessel. Water heating canister 107 comprises: base plate 202; said base plate being formed integrally with input pipe 203 and output pipe 212 for fluid flow into and out of the water heating canister device; top plate DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

201; one or more individual water distribution units 301 to 304; and a central copper tube of the order 11 mm in diameter said tube attachable to the base plate output pipe and forming part of an outflow passage.

Base plate 202, in the best mode embodiment of the invention includes a circular disc with a central aperture, of the order 11 mm in diameter, on an upper plane surface from which a tube 212, of the order l 'I mm internal diameter, projects perpendicularly on the opposite plane surface. Said tube 212 extends vertically down from the lower plane surface for a distance in the approximate order of 5cm providing a means for outflow of water from the device.

Laterally offset from the outlet pipe 212, is an inlet aperture 300, of the order 11 mm in diameter, on the upper plane surface of the circular base plate 202.

Extending vertically down from the underside of said base plate is inlet tube 203, is of the order approximately 11 mm in diameter, projecting vertically downwards for a distance, in the approximate order of 3cm. At this point, said inlet tube turns through 900 to continue in a horizontal plane parallel to and in a direction towards the edge of the base plate. Said inlet tube passing through 90 provides a means of fluid inflow. Said inlet tube thus incorporates an elbow to change the direction of inflowing water from the horizontal to vertically upwards. Inflowing water under pressure is thus directed towards a first water distribution unit 301 by route of inlet aperture 300 beneath the first water distribution unit.

Within a substantially cylindrical chamber formed by said water canister is positioned the water distribution assembly comprising a plurality of water distribution units 301 to 304. The water distribution units are assembled by being slid over a central copper tube, eg a conventional 11 mm internal bore plumbing tube, which extends centrally through each water distribution unit and also forms a passage between an outlet aperture immediately under said top plate at an DRAFT PATENT SPECIFICATION COMMERCIAL CONFIDENTIAL upper end of said chamber, and said outlet pipe 212 at a lower end of said chamber. The copper tube locates in the internal diameter of outlet pipe 212.

At the periphery of said base plate, four apertures 302, each of the order 3mm to 5mm diameter are distributed evenly around a circumference of said plate 212, each aperture being 900 offset from the center of the base plate to an adjacent said aperture. These apertures are intended to provide a means for inserting tension rods 204, 205, 206 extendingvertically between the base and top plates, perpendicularly to said plates.

On the upper surface of base plate 202, in a central position surrounding the central aperture leading to the outlet pipe 212, two projections 400 are situated. Said projections exist on horizontally opposite sides of said aperture on the upper base plate surface. Said projections extend perpendicularly away from said base plate upper surface by a distance of the order 2mm to 5mm. Said projections serve to locate the first individual water distribution unit 301 in a central position at the base plate.

Preferably, said base plate has the thickness of the order of 4mm to 7mm, and is of stiffness sufficient to withstand a water pressure of 10 bar, inside said canister.

The top plate 201 comprises a circular disc with a central circular mounting, of the order 11 mm to 14mm in diameter, on a lower plane surface. Said mounting houses an annular seal, and together said mounting and seal provide a means of securing the adjacent water distribution unit 304 by contacting the protruding projections of the circular central support of the adjacent water distribution unit. The upper planar surface of the top plate is smooth.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

Preferably, said top plate is of the order of thickness 4mm to 7mm and is of stiffness sufficient to withstand a water pressure of 10 bar, inside said canister.

At the periphery of said top plate, four apertures 305 to 308 passing through the plate, of the order 3mm to 5mm are distributed evenly on the planar surface, each aperture being 900 offset from the center of the top plate, to the adjacent aperture. These allow for insertion of tension rods 204, 205, 206, one per aperture extending from top plate to base plate.

Preferably, said tension rods each extend perpendicularly from top plate to base plate when in position, allowing a threaded overlap at either end to secure each rod to base plate and top plate respectively using a screw tightening nut, with the support rods each acting as a bolt. In this way, said metal tension rods connect base and top plates and can be utilized in conjunction with said tightening nuts to secure base and top plates to said heating can ends in conjunction with seals to form a water-tight seal. As a result, water may only enter and exit the heating canister by inlet pipe 203 and outlet pipe 212.

The invention is not limited by the mechanism of fixing top and base plates by the use of tension rods. Alternative means of securing said top and base plates in position could be provided by flanges either as part of or welded to the heating can ends providing a means for fastening said top and base plates to the heating Gan ends by the use of suitable bolts and tightening nuts located through suitable apertures in the flanges and top or base plate respectively.

The copper tube is located to the central aperture in the base plate and thereby also to the outflow pipe 212 forming a part of the base plate. The attachment is by a push fit. As such the copper tube forms a central supporting column onto which each individual water distribution unit can be inserted by locating a central support portion of each water distribution unit around the DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL copper tube so that each water distribution unit will slide down the tube in order to sit in correct position.

The water distribution device is enclosed between base and top plate by a cylindrical wall 200 capable of withstanding water pressures of the order 10 bar and more. Said cylinder forms a watertight seal at base and top plates, hence water may only enter and exit the water distribution unit by means of said inlet pipe 203 in the base plate and exit by entry to the central copper tube adjacent to the top plate 201. Water entering the copper tube by the latter means can flow out through the central outlet pipe 212 in the base plate 202.

Preferably, said cylindrical wall 200 comprises one or more heating elements and is envisaged to encapsulate a thick film technology based heating element. Wherein when connected to an appropriate power supply, said element results in heating of the entire cylinder wall 200 and the inner surface of said cylinder becomes the focal point for heat exchange between water and the element.

The invention is not limited by the use or inclusion of thick film technology based heating elements. Conventional electric heating elements including coiled elements could also be used at sites both internal and external of the heating can. One alternative is to attach a suitably coiled electric heating element to the external walls of the heating can. Such an element could extend around the heating can in a spiral from base to top such that the element passes around the heating can a plurality of times. The element could be suitably soldered, welded or braised to the heating can wall. In this way, a conventional heating element could be used to heat the heating can wall such that the internal wall of such a heating can could be used as the focal point for heat exchange between the heating can wall and a fluid eg water contained within the can.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

Referring to Fig. 6 herein, each water distribution unit comprises; a hollow, cylindrical central support tube 600, projecting perpendicularly vertically upwards and downwards for a distance in the order of 2cm to 4cm in each direction from a vertical center, such that a continuous tube is formed through; and a vertically central circular baffle plate 601 radiating horizontally and perpendicularly to the central support throughout 3600, such that the baffle plate has a radius in the order 2cm to 5cm, taking the lateral point of space within the central support as the geometric center of the baffle plate. The baffle plate is provided with a plurality of through apertures through which water may pass. Said baffle plate extends towards the cylinder wall horizontally in all directions, leaving only a fine space of the order less than 1 mm between the baffle plate edge and the cylinder wall. Said fine space provides a means for limited water transfer between chambers formed by vertically adjacent baffle plates or a baffle plate and base or top plate. Each baffle plate is provided with a plurality of substantially cup shaped deflectors for deflecting a direction of flow of water through a corresponding respective said aperture. In Fig. 6 herein, only three deflectors are visibly illustrated, the fourth deflector, present in this embodiment being obscured by the central support.

The baffle plate and central support are continuously connected components. Accordingly, said baffle plate forms a horizontal partition within the surrounding metal cylinder. In this way vertically adjacent baffle plates separate the metal cylinder into a plurality of individual chambers 401 to 405.

Referring to Fig. 4 herein, a first chamber 412 is formed between the base plate 202 and first baffle plate 402 of the first distribution unit 301, a last chamber 405 being formed by the baffle plate of the last distribution unit 304 and the top plate 201. All intermediate chambers (402, 403, 404) are formed between vertically adjacent baffle plates of individual distribution units. Accordingly, the number of chambers is governed by the expression:

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

C=n+l where C = number of chambers, and n = number of individual distribution S units.

In the best mode, each baffle plate is provided with four apertures 602, each of the order 6mm to 1Omm in diameter. Said apertures are evenly distributed around each baffle plate, each aperture being 900 circumferentially offset from its neighboring adjacent aperture. Said apertures provide the main fluid flow route between adjacent chambers formed by vertically adjacent baffle plates or a baffle plate and base or top plate. Water flow paths between chambers is illustrated using arrows in Fig. 4 herein.

is On one planar side of each baffle plate, and when considering the flow of water, on the side furthest from the base plate 302, above and around each of the four baffle plate apertures 602 is situated a deflector 309. Said deflector deflects water radially outwards towards the walls of the surrounding metal cylinder 200. Each deflector comprises; a raised, near circular, platform 603; a curved near cylindrical support 605; said near cylindrical support forms a wall, of the order 3mm to 5mm in height, located around the edge of each aperture in each baffle plate. Said support extends around each baffle plate aperture circumferentially for approximately 27T, around a geometric center being the center of said aperture. Said wall ends are such that an isosceles triangle can be drawn parallel to the plane of the baffle plate from the center of the central support to the two wall ends, where the sides of the triangle equal in length extend from the geometric center of the deflector located in the space within the central support. Said wall ends are at a furthest possible intersection of the equal length sides of said isosceles triangle and said near cylindrical support.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

Each of said deflector has a raised, near-circular platform 603, which is welldescribed as a solid circular disc with a segment removed, such that the edge furthest from the center of said deflector is flattened. As a result, the crosssectional area of the circle is restricted to approximately two-thirds compared to 5 that predicted by its radius. The platform has an external diameter of approximately 1cm. Said platform is aligned parallel above the baffle plate supported from said baffle plate at all curved edges by a continuous support wall 605, vertically connecting the platform and baffle plate. Said support 605 rises perpendicularly from said baffle plate raising said platform above and spaced 10 apart from said baffle plate by a distance in the approximate order 5mm to 1 Omm.

Said deflector is constituted by said raised, near-circular platform 603 and said support 605. In such an embodiment, baffle plate and deflector are continuous structures.

Such a deflector 309 exists at all four baffle plate apertures 602 in each individual distribution unit (Fig. 6), such that each baffle plate is polarized in that all four deflectors are situated on one planar baffle plate surface. When assembled, the individual water distribution units are each in a same orientation with one set of deflectors on the upper side of the lower/preceding baffle plate. This results -in one set of deflectors per chamber excluding the first chamber 401 formed between the base plate 202 and the first baffle plate 402.

Individual distribution units fit together where their central supports meet.

2S Adjacent central supports lock together due to the shape of the ends of the central support. Said central support ends consist of two protrusions, on opposite sides of the central cylindrical support extending 2mm to 5mm beyond the lowest part of the central support. As each individual unit is formed in the same orientation, adjacent individual distribution units must be rotated by 450 to allow the central supports to interlock. This results in each set of baffles i. e. four baffles DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIA in one chamber, being rotated by 450 in orientation relative to deflector sets in adjacent chambers.

The first individual water distribution unit is located on two projections 400 from the base plate 202. These mimic the protrusions of an adjacent individual water distribution unit. The first individual water distribution unit is thus centrally located within the cylindrical wall 200.

The protrusions 604 on the final individual distribution unit which contacts the top plate 201 provides two apertures, formed by the top plate 201 and central support protrusions 604. As the chambers fill with water and the water rises, heated and mixed water is forced out through said apertures and into the copper tubing. Consequently, the copper tubing is required to be shorter in length than the entire distribution unit by length in the order of 1 cm to 2cm.

According to the above described protrusions used to interlock adjacent individual water distribution units, it is provided that any number of individual distribution units with any number of water deflectors per individual distribution unit may, in theory and practice, be located around a copper tube by the central support and be interlocked. Ultimately, the limiting factor on the number of individual water distribution units present in any single heating canister is the cylindrical length of the heating canister.

It is well known that mineral compounds, eg calcium and magnesium salts present in many domestic and industrial water supplies are often deposited in water containing vessels, particularly when considering slow moving and/or heated water. This type of water is known as hard water, generally composing two classes of temporary hardness and permanent hardness. Temporary hardness is a result of calcium bicarbonate dissolved in the water. On heating, this forms calcium carbonate, which is insoluble and is precipitated.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL -24 CaC03+ H CaffiC03)2' 20 + C02 Permanent hardness is due to other mineral salts, eg magnesium sulphate, and increased precipitation of these salts is related more to the velocity of water flow rather than water temperature. Together, these precipitated deposits are commonly known as limescale or scale. Scale formation often increases with the temperature of stored water. Scale can build up to impede water flow eg in pipework, or can form on heating elements and impair efficiency by forming an insulating layer which impedes the efficient transfer of heat. This may cause excessive element heating in specific localities along its surface and in turn may lead to a reduction in the element lifespan. Scale deposition varies with the geographical location of the water source forming the water supply. Scale can be a chronic problem in some regions, with much research having previously been is directed at chemical and physical methods of decreasing or preventing scale deposition. For consumers experiencing a decreased water appliance lifespan due to scale deposits, be it by decreasing element lifespan, blocking pipework etc., a shower unit incorporating features reducing scale deposition will be of value.

Considering a hypothetical tubular vessel incorporating heating elements extending both circumferentially around and vertically up and down the tube for use as a means of heating water in electric shower units, in order to be heated quickly and efficiently, water is required to flow over all areas of the vessel wall which is acting as the heat exchanging surface. However, in conventional laminar flow the velocity of flow of fluid is decreased significantly at a vessel wall, where at an infinite point along the vessel wall behind the point of maximum flow velocity, water ceases to flow. The result of this effect is a reduction in flow velocity in Mead zones" at the vessel wall. As noted above, a decrease in flow DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL velocity promotes scale deposition, which in turn reduces efficiency of water heating.

Dead zones' are therefore prone to scale build-up, and considering a S tubular vessel, scale is likely to be deposited radially towards the vessel center, in any one plane, initially at the vessel wall. Therefore, if the vessel wall were to incorporate an element and act as the heat exchanging surface, the heat exchange would be diminished and element lifespan may well be reduced, unless dead zones can be eliminated or reduced.

Consequently, elimination of "dead zones" resulting from laminar flow is required whilst allowing for efficient water mixing and heating in a cylindrical heating chamber, where heat exchange is occurring at the cylindrical chamber wall.

is Referring to Fig. 7 herein, laminar flow shows a three dimensional uniform distribution of flow velocity when considering a unidirectional 701 pulse flow as illustrated in two dimensions in Fig. 7. Such a distribution of flow velocity describes a maximum flow velocity at a point farthest from any point on the wall described by a circumference of the plane perpendicular to the cylinder in which the point of flow is being considered. The same distribution also describes the flow velocity as decreasing 702 with decreasing shortest distance from the point of flow being considered to the cylinder wall 700. As a result at an infinite point behind the point of maximum flow velocity, flow ceases and flow velocity is equal to zero. When considering the flow of hard water in the cylinder, the decreased peripheral flow velocity will facilitate scale deposition.

When considering general laminar flow in a tubular vessel, e.g. a pipe, the macroscopic realization of the pulse flow consideration is the formation of 'dead zones' of fluid flow 703 (crossed area in Fig. 7) at the vessel walls 700. These DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL dead zones' are regions of low velocity flow. When considering flowing water, dead zones result in an increased probability of scale deposition. This is especially true when considering hard water. Said hard water can be of permanent or a temporary hardness.

As 'dead zones' form at vessel walls, scale deposition is most probable at this location. Where this coincides with the heating element a decrease in heat exchanging efficiency and element lifespan is to be expected.

In the specific embodiment of the present invention the water distribution units disrupt a laminar flow by creating turbulence at many places within the canister. This results in the loss of a high probability of scale deposition at the vessel walls 700 due to a disruption of the'dead zones'703. When considering a heater element incorporated in a cylindrical vessel wall, disruption of 'dead zones' is will decrease scale deposition at the vessel wall and increase heat exchanging efficiency at the vessel wall and prolong the life of the element.

In the case of a cylindrical vessel where the walls contain the heating element in order to obtain efficient mixing and heating of water further to a simple radial water distribution, a system of mixing the water must be effected. In this way, mixed and heated water is aimed to be provided whilst prolonging element lifespan by reducing scale deposition at the vessel walls.

The specific embodiments of the present invention enable a first specific 2S method of flow for generating turbulent flow at the wall of a cylindrical heating element. Fig. 4 uses arrows to illustrate said flow method initiating with water influx through the inlet pipe 203 in said base plate 202. Inflowing water is changed in direction of flow 900 due to the 900 elbow formed by the inlet pipe 203 before it enters the cylindrical vessel. The result is a change in direction from a horizontal to a vertically upwards flow. Water under pressure is propelled through DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIA the inlet aperture 300 in the base plate and directly through the first chamber 401, exiting by a plurality of baffle plate apertures located vertically above the inlet pipe. This results in flow deflection immediately to the cylinder walls surrounding the second chamber 402. At the cylinder walls, water is randomly deflected, 5 resulting in a non- laminar flow which excludes 'dead zone' formation.

First chamber filling provides for further flow deflection as water enters the second chamber 402 by one of the baffle plate apertures. Additionally, water is pushed between the first chamber 401 and the second chamber 402 via the fine space between the baffle plate edge and the cylinder wall. This results in further random mixing of water, as water entering the second chamber 402 via the fine space between the baffle plate edge and the cylinder wall collides with water moving in various other directions.

Vertically adjacent baffle plates are rotated about a main central axis of the cylinder wall by an angle of 4Y. This provides for further deflection of water flow and ensures all circumferential regions of the heating can are utilized for water heating.

The combination of flow deflection by baffles and water transfer between chambers at the baffle plate edges results in turbulent water in the second chamber 402 being pushed together from a plurality of directions at or near the cylinder wall surface. This results in the disruption of any laminar flow and the formation of a purely turbulent flow. This prevents formation of "dead zones" of water flow and maintains flow of all water at an increased average velocity. The increased average velocity combined with constant flow deflection results in thoroughly mixed, turbulent water at the cylinder wall. This provides for a decreased scale deposition at any particular temperature as compared with a laminar flow case. The flow deflection and mixing of turbulently flowing water also provides for efficient heating of water by an element eg a thick film technology DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIA element, incorporated in the cylinder wall 200. Flow deflection and mixing and heating is repeated in following chambers 403,404, 405.

In the final chamber 405, following a flow deflection, mixing and heating, water is forced into the central copper pipe through apertures formed by the central support protrusions 604 and the top plate 201. Thus heated, mixed water flows down the central copper tube and towards the shower head.

Referring to Fig. 8 herein, there is illustrated a possible flow scheme of water showing routes of entry of water to a chamber and water mixing due to multiple water flow directions. Water passing between adjacent chambers by baffle plate apertures is deflected radially outwards 801 towards the cylinder wall. On impact at the cylinder wall 802, water is non-uniformly distributed in a nonlaminar fashion 803. Water entering the chamber by route of the fine space between baffle plate and cylinder wall 804 further contributes to water mixing. The resulting water flow is a non-laminar turbulent flow situated at, adjacent, or near to the cylinder walls. Thus heating and mixing of water are facilitated when considering a cylinder wall incorporating a heating element, and scale deposition is minimized by preventing formation of 'dead zones' of water flow.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIA

Claims (30)

Claims:

1. A water heating device, said device comprising:

a vessel having an inlet for ingress of water and an outlet for egress of S water; and deflection means situated internal of said vessel, said deflection means operable in use to deflect a flow of water through said vessel between said inlet and said outlet such as to cause a substantially turbulent flow of water within said vessel.

2. The heating device as claimed in claim 1, wherein said vessel comprises a wall surrounding a water chamber therein, said wall comprising a plurality of electrical heating elements.

3. The heating device as claimed in claim 2, wherein said vessel wall is heated by a plurality of electrical heating elements.

4. The heating device as claimed in claim 2 or 3, wherein said electrical heating elements are:

soldered; or welded; or braised to said vessel wall.

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL

5. The heating device as claimed in any of claims 1 to 4, wherein said vessel wall comprises an inner wall surrounding said chamber; an electrically insulating outer layer adjacent to said inner wall; and a plurality of sheet heating elements adjacent to said insulating layer.

6. The heating device as claimed in any one of claims 1 to 5, further comprising a thermostat device attached directly to said vessel wall.

7. The heating device as claimed in any one of claims 1 to 6, wherein said water heating vessel is substantially cylindrical.

8. The water heating device claimed in any of claims 1 to 7, comprising a deflection means for producing turbulent water flow at:

said vessel wall or walls; or anywhere in said vessel.

9. The heating device claimed in any preceding claim, comprising a deflection means for directing water flow against:

a surface or surfaces; and/or said vessel wall.

2S

10. The heating device as claimed in any preceding claim comprising deflection means for causing water flow substantially:

against; and/or DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL adjacent to; said vessel wall.

11. The heating device as claimed in any one of claims 1 to 10, wherein said deflection means comprises a plurality of baffle plates arranged internally of said vessel, said baffle plates arranged in use, to direct a said flow of water in a direction transverse to a main internal surface of said vessel.

12. The heating device as claimed in any of claims 1 to 11, wherein said deflection means comprises a plurality of spaced apart baffle plates contained within said vessel, wherein said inlet is arranged to input water to said vessel at a first end of said vessel, and said outlet is arranged to outlet said water at a second end of said vessel, such that to pass between said inlet and said outlet, a said flow of water must encounter said plurality of baffle plates within said vessel.

13. The heating device as claimed in any one of claims 1 to 12, wherein said deflection means comprises a plurality of baffle plates, each said baffle plate comprising at least one aperture, wherein said baffle plates are arranged sequentially within said vessel between said inlet and said outlet, such that in use, a said water flow passing between said inlet and said outlet must encounter each of said plurality of baffle plates, wherein said apertures of said baffle plates are offset with respect to each other such that in order to pass through said plurality of apertures said water must follow a plurality of directions of flow between said inlet and outlet.

14. The heating device as claimed in any one of claims 1 to 13, wherein a said deflection means comprises at least one baffle plate comprising a plate member extending across said vessel in a direction transverse to the main DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL central axis of said vessel, said plate member having at least one aperture, and at least one flow deflector means positioned immediately adjacent said aperture for changing a direction of flow of water passing through said aperture.

15. The heating device as claimed in claim 14, wherein a said flow deflector means comprises a substantially cup-shaped member having a first portion extending in a direction transverse to a main plane of said baffle plate and a second portion extending in a plane substantially parallel to said main plane of said baffle plate.

16. The heating device as claimed in any one of claims 1 to 15, wherein said vessel comprises:

a substantially cylindrical tubular outer wall; a first substantially planar end plate, closing off a first end of said substantially cylindrical tubular wall; a second substantially planar end plate closing off a second end of said substantially cylindrical tubular wall.

17. The heating device as claimed in any one of the preceding claims, wherein said deflection means comprises:

a plurality of baffle plates, each extending across said vessel in a direction transverse to the main central axis of said vessel, between said inlet and said outlet, wherein said plurality of baffle plates define a plurality of internal chambers, said chambers configured such that water passing between said inlet DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIA and said outlet must pass through said vessel from chamber to chamber and past said plurality of baffle plates.

18. The heating device as claimed in any one of the preceding claims, S wherein said deflection means comprises a plurality of baffle plates, each extending across said vessel in a direction transverse to the main central axis of said vessel, between said inlet and said outlet, wherein said plurality of baffle plates are arranged sequentially along a main central axis of said vessel, said baffle plates each extending transverse to said main central axis and spaced apart from each other to define a plurality of chambers there between, wherein said plurality of baffle plates are assembled such as to define a water passage for outlet of water, said water passage comprising said outlet, wherein a primary direction of flow of water between said inlet and said outlet is in a first direction, and water flowing through said water passage flows in a second direction, said second direction opposite to said first direction.

19. A water heating device, said water heating device comprising:

a substantially cylindrical tubular vessel, said tubular vessel comprising a wall having an inner layer surrounding a chamber formed therein; a layer of thermally conductive and electrically insulating material disposed externally of said inner layer; and a plurality of sheet heating elements disposed externally on said electrically insulating thermally conductive layer, DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL wherein by applying an electrical current to said plurality of heating elements, said heating elements operate to heat said inner layer in a said thermally conductive layer, such that said inner layer is capable of heating a volume of water contained within said chamber.

20. A method of deflecting a flow of water through a vessel compdsing one or more vessel walls.

21. A method according to claim 20, further comprising the steps of:

converting a laminar flow to a turbulent flow.

22. A method according to claim 21, further comprising the steps of causing a water to flow substantially:

against; and/or adjacent to; said vessel wall.

23. A method according to claim 22, further comprising the steps of producing turbulent water flow at:

said vessel wall or walls; or anywhere in said vessel.

24. A method according to any of claims 20 to 23, further comprising 30 the steps of directing water flow against:

DRAFT PATENT SPECIFICATION - COMMERCIAL CONFIDENTIAL a surface or surfaces; and/or said vessel walls.

25. A method according to claim 24, further comprising the steps of directing a flow of water in a direction transverse to a main internal surface of said vessel.

26. A method according to claim 25, further comprising the steps of deflecting water through a plurality of directions of flow between a vessel inlet and a vessel outlet.

27. A method according to claim 26, further comprising the steps of heating water by heat exchange at:

said vessel wall or walls; or anywhere in said vessel.

28. A method of heating a vessel wall or walls using one or a plurality of electrical heating elements attached to or part of said vessel wall or walls.

29. A shower unit comprising a water heating device as claimed in any one of the preceding claims.

30. A water heating device as claimed in any preceding claim for use in domestic and industrial water heating.