IE85978B1 - Dual chamber water heater - Google Patents

Abstract

ABSTRACT A water heater, comprising a storage unit that holds a first volume of water and which has a mains conduit that connects to a mains water supply, and a storage heating element to heat the first volume of water to a temperature between room temperature and boiling point, the water heater also having a boiling unit, adjoining the storage unit and adapted to hold a second Volume of water and having a boiling heating element adapted to heat and maintain the second volume olwater at a high temperature in use, the boiling unit also including a dispensing mechanism to allow a user to draw off water from the boiling unit. the heater having a connection conduit that runs between the storage unit and the boiling unit. so that the boiling unit can reeei\«'c water from the storage unit, the boiling unit and the storage unit separated by an airgap.

Description

BACKGROUND OF THE INVENTION Field of Invention This invention relates to hot Water heaters of the type used to provide hot water on demand.

Description of the Prior Art situations. Heaters of this type provide water of the required temperature only when this is ‘demanded’ by a user, by heating the water as it is demanded or drawn off by a user. The operation of instant heat units can generally be described as follows: when water is demanded by a user (e.g. by turning on or activating a tap), water at a temperature significantly below boiling point (e.g. room temperature) is supplied to the heater, either from a storage reservoir or from a mains supply. This water passes into the heating unit and is heated to the required temperature, usually by using a gas burner. The heated water is then supplied directly from the heating unit to a user, immediately after it has been heated. Larger, domestic instant heat units tend to be designed to have a greater flow, as they are intended to provide a large volume of hot water at a temperature suitable for wash.ing,'baths etc. However, the water provided by these larger units is usually too cool for cooking, beverage preparation, etc.

Smaller ‘instant hot water’ units are becoming increasingly popular for use in situanbns where a smaller volume of hot water is required each time the heater is used, but where water at a higher temperature is required, and where the unit will be used more £requently. For example, in office kitchens a heating or boiling unit will be used at frequent intervals throughout the course i of a working day for beverage preparation or similar. Water at a temperature close to boiling is required every time Water is drawn off.

Office—type units are generally smaller than domestic instant heat units. As they are intended to provide lower volumes of Water for any one use or at any one time, it is cost-effective to use units of this type to supply water at a high tcfmperature. In units of this type, water is either supplied to the heater directly from the main circuit (at room temperature), or a small amount of water is heated and stored at an intermediate temperature. This water is then heated to a higher temperature and provided to a user when it is demanded.

One problem with all of the heater types described above is that of heating efficiency.

Considerable power is required to heat (and then store) hot water at temperatures significantly above room temperature. Most heater designs are a compromise between storage volume, storage‘ temperature, instant heating efficiency, and overall volume (the overall volume including insulation or other external accessories). Design improvements have generally been driven by consumers demanding greater efficiency (diat is, lower power bills). Other considerations that are becoming more important include ecological issues, with fuel (heating) efficiency becoming more important. Also, health and safety issues are becoming increasingly important. If water is being provided at high temperatures, it is important that the possibility of a user being accidentally scalded or bumt is minimised.

In order to improve efficiency, it is known in the art to construct tanks that are divided by internal partitions or similar into two distinct sub-chambers or sub-tanks. One of these sub- charnbers receives mains Water and heats it to an intermediate temperature -— below boiling but above room temperature. This heated water is then passed through to the second sub-chamber where it is heated to a higher tempetatu1'e (e.g. close to boiling) for delivery to a user. The second, higher temperature sub-tank is replenished with water from the first sub-tank as water is drawn off. Usually, the first sub-tank has a greater volume than the second, higher temperature, sub-tank. This dual tank design has the advantage that the lower temperature body of water will not lose heat energy as rapidly as water heated to close to boiling, as the thermal gradient between the lower temperature water in the first sub-tank and atmosphere is shallower.

However, when higher temperature water is required, less energy and time is needed to heat the w'a1’ct in the second chamber {tom the intermediate temperature to :1 high tctnipcmturc. This armngctnent allmvs high temperature xvatcr [D be pmvided at itttcgulzir intc.rvals t:.g. to prepare E')cv'eragr:s throughout :1 working day in an office, but increases the ovcmll cfficicricy of the systc-in.

Examples of this type. of design are Sl'1(')Wf1lf1 US 3,383,495, US 4,575,615 and US 4,'.:‘57,l82.

Another type of design uses :1 nested ti-ml: cunfiguraticm to increase efficieiicy. In this cc)nfigurat:ion, the smaller (high tempemmire) rank is nested iriside 21 larger (intenncdiatc temperature.) outer tank. Tlic water in the outer tank is limited to an intermediate temperature, for example 6{J"C, and the water in the inner tank is heated to a higher [.t:i1'1pCtatu1‘L‘. (cl()sc to boiling) for dispensing to a user. Tliis configumrinn 11:16 the advantage that the outer ts-ml: and its contents act at least partially as an insulating jacket around the higlier temperature. chamber. In a shnilnt mariner to tl‘Hlt()LItl.ll1L‘Cl above, high temperature water at indeterminate or irregular int.crv:1ls can he provided, with increased sysrcin efficiency.

Examples of this type of design are shown in US 2,386,949 and US 3,6’! 7,700.

In this specificmion wlietc reference has been made to patent 5pcCificat.ir>ns, other external Llocuinenrs, or other sources of informamm, this is geiierzilly for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherxvisb, reference to 511:}: external documents is not to lJe.Cnr1s£rnc(l as an fldmissinn that such documents, or such sources of information, in any jurisdiction, are prior art, or form part. of tlic common general knmvledgc in the art.

SUMMARY OF THE INVENTION It is an object of the present invention to provide :1 hot water heater that goes some way towatds overcmning the disadvzmtages described above, or which will at least ;_.1s:0vidc LISCITS with a useful choice.

Accordingly, the inven.t.ir.>n may brcincll}! be said to consist in :1 wrmri: heater For providing hot water to a user, coniprising: :1 storage unit adnptecl to hold :1 First volume 0f\v:1ter, and lmving :1 mains crmduit adapted for connection to 2: mains water supply so that said stoitage unit can re.ce.ivc water from said mains water supply, said storage unit silsn lizwing 2. storage. heating eletmtnt ad:1.p’red m lw:-it and maintain said first volume of water at an intermediate temperature between room temperature and boiling point in use, a boiiing unit, adjoining said storage unit and adapted to hold a second volume of water and having a boiling heating element adapted to heat and maintain said second volume of water at a high temperature in use, said boiling unit also having a dispensing mechanism adapted to allow a user to draw off water from said boiling unit, a connection conduit, running between said storage unit and said boiling unit, so that in use said boiling unit can receive water from said storage unit, said boiling unit and said storage unit directly adjacent or adjoining one another and separated by an airgap, said storage unit located above said boiling unit, wherein the base of said storage unit is a convex surface, and the top of said boiling unit is a concave surface, said base adjacent to said top.

Preferably the curvature of said convex surface substantially matches the curvature of said concave surface so that the size of said airgap is the same size between a substantial portion of said concave and convex surfaces.

Preferably said dispensing mechanism comprises a pump, in fluid communication with said boiling unit.

Preferably said dispensing mechanism also comprises a dispensing conduit, one end of said dispensing conduit fluidically connected to said pump to receive said water from said boiling unit via said pump, the other end of said conduit adapted for connection to a user—operated tap.

Preferably the relative capacity and dimensions of said storage unit and said boiling unit, the relative curvatures of said concave and convex surfaces, and the size of said airgap, are calculated so that heat transfer to the storage unit from the boiling unit compensates for heat losses from the storage unit to the surrounding environment.

Preferably the relative capacity and dimensions of said storage unit and said boiling unit, the relative curvatures of said concave and convex surfaces, and the size of said airgap, are calculated so that heat transfer to the srcitagc unit from the boiling unit compensates for heat iosscs from the storage unit to the surrounding envimnment and the energy input required to said boiling unit clczncnt to compcnsate for said heat losses is minimised.

Preferably said zzirgap is bctxveeu (mum and 15mm.

Even more preferably sad airgap is 9mm. l’refernbI};' the capacit}-' of said storage unit is bet\vr:cn 10 and 14 litres, and the capacity of said boiling unit is lmtween 1.5 and 3.5 litres. "liven more preferably, the capacity ofsaid storage unit is '12 litres, and the capacity‘ of said boiling unit is 2.5 litres. l’rcfc1'ably said intermediate stmtagc temperature is between ?l‘)—9D"C.

Jélvcn more preferably said inteimcdiate storage temperature is :1 set point temperature of substami-.1lly 80" .. l’rcferab1~5r said boiling unit further comprises :1 rim, aligned substantially vertically and running around the top edge of said boiling unit, said storage unit testing on said rim in use.

Preferably said storage unit and said boiling unit are ciiscular in plan view, each lnzwing :a diameter in the region of 27cm.

Preferzibly when said storage unit and said boi.l.ing unit are assemlalccl to form part of said water heater, the height of said x ate: heater from the base of said boiling unit in the top uf said storage unit is in the region m‘ 40cm.

Pref-srztbly said water heater further compmcs 2: uasirig, said sturagc unit and said boiling unit located within said casing in use.

Preferably said water heats: further coinprises insulating material, the space bchvcen said water hea rev and said casing filled with said insulating material, so that said insulating material surrounds and fully exicloses said storage unit and said boiling unit.

Preferably any space between said water heater and said casing is filled with an insulating material, filling said casing, and surrounding and fully L‘,flCl()Sl11g said storage unit and said boiling unit. .. l’refc1-ably said insulating rnaccrial. is Forrxnccl as two separate expanded polystyrene pieces that together form an insulating shell that encloses said water. heater. l”rcfc1:al;>1y the contents of said l)(.;il.ing unit is limited aml mziinminccl zit a tcmpcraliurc lictween 92"C and ‘)‘)‘’{I by said boiling element.

Even more pricfcrably, the contents of said boiling unit is limited and mziincaincd at a temperature of 3°C below boiling point by said boiling element.

Preferably said boiling element has a power output in the region of "L8 li\l¥-’. l”rcfc1'ab1_y said storage element lias 21 power output in the region of 1.8 kW.

Preferably at least part of the length of said connection conduit is located in said storage unit, submerged in the upper third of the contents of said storage unit.

Preferably that and of said connection conduit that is locatml in the storage unit faces upwards.

Prcfcmbly when said storage unit is filled to the required level, said end is just below the surface of said contents. l)tCf€2‘fll_)l)=' said storage. unit further comprises :1 dispensing conduit adapted for connection to :1 tap to enable a user to draw off water {mm said storage unit, said storage unit having an outlet, said dispensing conduit connected at said outlet, said storage unit also having :1 balance valve located at said outlet, said balance valve adapted to cool water exiting said storage unit to :1 maximum temperature of 70°C.

Ptefm-ably said watei: heater further compiiscs a control unit adapted to receive signals from probes and switches in said water heater, and transmit instruction signals according to pro» programming, and snici storage unit further comprises :1 pressure switch adaptecl to send :1 storage unit full signal to said control unit when said storage unit is filled to the required pressure, and a 3-ztorzigc unit deplvted signal to said cmiti-ml unit when said smxage unit is not fillc:-.d to S1l'l1'.'l t'eq\Ji1'ed pressure, and said boiling unit further comprises :1 hailing level probe adapted to send :-1 boiling unit full signal tu said control mechanism when said boiling unit. is filled to Like‘: rcquirccl bc.3i1inglcvcl,and a boiling unit depleted signal to said control unit when said boiliiig unit is not filled to said xczquircd boiling level, said mains conduit fiurther com risin a mains 311 l' in , said control unit sendin P 8 P l P . insrructirjn signals to said mains supply tap to contirol said mains supply tap, said connection conduit further compr..ising :1 connection mp, said C0nl1‘Ol unit. sending iiisttuction signals to said connection mp to control said connection tap, said boiling level probe sending said boiling unit, depleted signal to said control unit when water is drawn off from said boiling unit via said dispensing mechmnsm, said control unit instructing said coimection tap and said mains supply tap to open in response to receiving said boiling unit depleted signail, said storage unit receiving additional water from said mains C.(’.)I'1du1t, said adclitizinal water displaciiig at least part of said first volume of water and causing part of said first volume ofwater to pass into said boiling unit via said connection conduit, said boiling level probe sendirig said boiling unit full signal to said control unit when said boiling unit has been refilled, said control unit instructing said connection tap to close in response to rec.eiVi11g said boiling unit full signal, said storage pressure sensor sending said storage unit full signal to said control unit when said storage tank has been refilled, said control unit instructing said mains supply tap to close in response to receiving said storage unit full signal.

Preferably said storage unit further comprises 21 thermostat, said thermostat activating said storage element when the teinpernmxe of the contents of said storage unit Falls below a set point. temperature level of substantially 80"C.

Alternatively said thermostat sends a signal relating to the temperature of the con.tem.s of said storage unit to said control. unit, said control unit activatiiig said storage element when the tenipemtnre tn? the contents of said storage unit drops below :3 set storage unit rempe-.mru1'e.

Preferably said set storage unit teinperature is 80"C.

Prefer:-Llzly said boiling unit fiittlier comprises :1 thermistor, said thcrinistor act‘ rating said boiling heating element. when the teinpexaturc of the contents of said boiling unit drops below :4 set boiling unit temperature.

Preferably said set boiling unit temperature is 95°C.

To those skilled in the art to which the invention relates, in:-tny changes in construction and xvidcly difTe1'i11g cmbtxiirnents and. applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The ctisclosures and the dcscripticms herein are purely illustrative and are not intended to be in any sense limiting.

The term “comprising” as used in this specificati<:>t1 means “consisting at {cast in part of”. ‘)i"hcn ims.-.rprct.ing each statcxncnt in this specificatbn that includes the term “comprising”, features other than that or those prefaced by the term may 2113:) be present.

Reinteci terms such as “c<:mprise” and “comprises” are to be interpreted in the same nmnner.

The invention consists in the foregoing and also envisages cmlstructions of which the f<)l1owing gives examples.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred forms of the present invention will now be described with reference to the accompanying drawings in which; Figure 1 shows a preferred embodiment of a hot water heater, with an outer casing ' shown in outline, and a control unit shown located in a recess on the casing.

Figure 2 shows an exploded View of the water heater of Figure 1, with a heater unit, A conduits, surrounding insulation shown,’ all located within the outer casing in use. ! Figure 3 shows the exploded view of Figure 2, with the heater unit also shown separated or exploded in order to show an upper storage unit and a lower boiling unit of the heater unit.

Figure 4 shows a cutaway View of the heater unit of Figures 2 and 3, with internal detail of the storage unit, the boiling unit and the conduits that run between the units shown.

Figure 5 shows a View of the storage unit and the boiling unit assembled with the control unit connected, and detail of the conduits that run between and which feed the units also shown.

Figure 6 shows a perspective view of a tap that can be used with the hot water heater.

Figure 7 shows the tap ‘of Figure 6 mounted on a benchtop.

Figure 8 shows an exploded view of the tap of Figure 6, with the main sub- components and sub—assemblies shown, including a user operated lever sub—assembly_.

Figure 9 shows a detailed exploded view of the lever sub-assembly shown in Figure 8.

Figure 10 shows the lever sub-assembly of Figures 8 and 9 assembled.

Figures 11a-c show cutaway side views of part of the tap of Figure 6, with detail of the lever sub—assernbly of Figures 9 and 10 in three posidons; Figure 1121 showing the lever in a first or off position, Figure 1 1b showing the lever in a posifion where a user has pressed downwards ‘and Figure 11:: showing the lever in a position where a user has pulled upwards.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS \X/hile the invention is susceptible to embodiment in different fonns, a specific preferred i embodiment is shown in the drawings, and described in detail. The present disclosure is to be considered an exernplification of the principles of the invention, and is not intended to limit the invention to that as illustrated and described herein. The preferred embodiment is described below in relation to a hot water heater or hot water unit of the type used to provide water for beverage preparafion in an office or similar. It will be appreciated, however, that the present invention can be used in any application where it is beneficial to provide hot water on demand.

Figure '1 shows a View of a preferred embodiment of a hot water heater 101 or hot water unit enclosed by an external or outer casing 100, shown in outline, the water heater 101, the casing 1 00, and the other secondary items forming a heater unit. The main components of the hot water heater 101 are located inside the external casing 1 00 in use. In the preferred embodiment, the casing 100 forms part of the hot water heater. However, the internal hot water heater 101 is referred to as a separate item from the casing 100. Where ‘water heater’ is referred to in this specification, this should be taken as either including or excluding the casing 100, as appropriate. Where ‘heater unit’ is used in this specification, this refers to the casing 100, the hot water heater 101, and all the secondary items such as a control unit 123, insulation 102, etc. In use, the heater unit is intended to be located in a storage space such ‘as a cupboard under a kitchen sink or The external casing 100 can be removed or opened to allow settings to be adjusted, maintenance to be carried out, etc. The casing 100 acts to protect the internal components from accidental damage, and also helps to protect users from inadvertent contact with hot surfaces, etc. In the preferred form, the space between the casing 100 and the outer A skin of the hot water heater 101 can be filled with insuiative material 102, such as expanded polystyrene foam.

A number of external ports pass through the casing 100, so that conduits 104 and similar apparatus can pass through the casing 100 to connect with the water heater 101. The casing includes recesses for the location of external control panels, power points, or similar. These power points and external control panels are shown generally as panels 103 in Figure 1.

Figures 2 and 3 show exploded views of the preferredform of the heater unit. The heater unit has a casing 100, water heater 101, insulation 102, control panels 103 and conduits 104. The preferred shape of thelwater heater 101 is cylindrical, with two rounded end caps. It should be noted that a water heater with flat ends could also be used. When the water heater 101 is located in the casing 100, there is a space between the generally rectangular or cuboid casing 100 and the water heater 101. This space between the casing 100 and the external skin of the water heater 101 is filled with the insulating material 102. I As shown in Figures 2 and 3, the preferred form of the insulating material 102 is two separate pieces of expanded polystyrene, brought together to enclose the water heater 101.

These two insulating halves are in turn enclosed by the casing.100.

As shown in Figure 3, the water heater 101 is comprised of two separate units, an upper storage chamber or storage unit 110, and a lower boiling chamber or boiling unit 11 1. The two units 110 and 111 ‘nest’ in use, the units directly adjacent or adjoining one another, with the curve of the concave top 107 of the boiling unit 111 matching the curve of the convex base 106 of the storage unit 110, the convex base 106 adjacent to the concave top 107. The preferred form of the storage unit has a convex curved base 106 (and a curved top) as this form allows the contents to be stored under pressure, whilst keeping the walls reasonably thin. The boiling unit has a rim 130 standing proud of, and running around the circumference of the concave top . The concave top 107 follows the curve of the convex base 106 of storage unit 110 as this allows the airgap between the two to be kept substantially cgnstant. The rim 130 is a continuation of the wall of the boiling unit 111 in the preferred embodiment, and is substantially vertical. The outer part of the base 106 of the storage unit 110 rests against this aim 130, so that there is no direct contact between the base 106 and the top 107. It should also be noted that when the ‘water heater 101 is assembled and ready for use, the two units 110, 111 are not physically connected (i.e. they are not attached together by welding, gluing, clamping etc).

Instead, the units 110 and 111 are kept in position relative to one another by their mutually interlocking or nested shapes, and the surrounding insulation material 102. It should also be noted that the rim 130 as described above follows the circumferential perimeter of the boiling unit 111. ‘However, the rim 130 does not have to be at the outer circumferential edge ~ it could be located slightly’ radially inwards of the circumferential edge. Also, although it is preferred that the rim 130 is a continuous loop, the rim 130 could be discontinuous in other embodiments.

Both the storage unit 110 and the boiling unit 111 are formed from copper in the preferredernbodiment. The preferred capacity of thestorage unit 1101s approximately 12 litres, and the preferred capacity of the boiling unit 111 is approximately 2‘/2 litres. Each of the units 110, 111 has a diameter of approximately 30cm, and the total overall height of the water heater 101 once asseznlaled is approximately 40cm.

The operation of the heater unit, the internal structure of the two units 110 and 111, and the external connections between each of the units 110, 111 and other elements of the system will now be described with particular reference to Figure 4.

Figure 4 shows the storage unit 110 nested into the concave top part of the boiling unit , as has been described above. The surrounding insulation 102 and casing 101 are not shown.

Each of the units 110, 111 contains a heater element to heat the water that is stored in the units 110, 111 to the required temperature. The storage unit element (storage element 121) passes into the side of the storage unit 110 at approximately mid-height of the unit 110, and is preferably aligned substantially horizontally. The boiling unit element (boiling element 120) passes in through the side of the boiling unit 111, also preferably aligned substantially horizontally. \7i7hen the two units 1 10, 111 are brought together, with the (upper) storage unit 110 resting on the rim 130, an air gap 105 is created between the convex base 106 of the storage unit 110 and the concave top 107 of the (lower) boiling unit 111. In the preferred embodiment, the curvature of the base 106 and the top 107 substantially match, so that the air gap 105 is a substantially constant 9mm gap at all points between the base 106 and the top 107. It should be noted that the Curvature matching does not have to be identical at all points between the two surfaces. However, it is preferred that the air gap is constant across a substantial portion of the two surfaces. In the preferred embodiment, the substantial portion amounts to 80% or more.

No further support is necessary to keep the units 110, 111 in place relative to one another. However, the insulation material 102 in the preferred form provides additional support to the two water tanks 110, 111.

As described above, the capacity of the storage unit 110 is approximately 12. litres. The storage unit 110 is kept topped up to this capacity by a connection to a mains water supply mains conduit 112, which passes into the side of the tank 110 close to the base 106. The mains supply water entering the tank 110 is at or close to room temperature, and as it enters the storage unit 110 it sinks to the bottom, below the heated water already present in the storage unit 110.

When wateris drawn off from the storage unit 110, the storage unit 110 is topped up to its 12 litre capacity from the mains conduit 112. The storage unit 110 operates as a normal mains I pressure water heater by allowing the room temperature pressurised mains water entering via mains conduit 1 12 to push out the hot water within storage unit 110 when water is drawn off from the water heater 101.

The storage element 121 beats and. maintains the contents of the storage unit 110 at ‘an intermediate set point temperature of substantially 80°C. It is preferred that the water in the storage tank 110 is maintained at a set point temperature of 80°C. However, it is preferred that the temperature of the contents of storage unit 11 0 does not significantlyexceecl this temperature. The storage element 121 is constructed as a standard heating element of the type that is we]1~known in the art, rated at approximately 1.8 kW in the preferred embodiment.

Storage element 121 is powered by a connection to a mains electricity supply ‘that is controlled by a control unit 123, located on or recessed into the outer casing so that it can be accessed by a user. The storage unit 110 also contains a temperature sensor such as a thermostat (not shown).

If the temperature of the contents of the storage unit 110 falls below a lower temperature level — e.g. just below 80°C, the thermostat activates the storage element 121 to raise the temperature back to the set point temperature of 80°C. Once the contents of the storage unit 110 has been raised to the required temperature, the thermostat de-activates the storage ‘element 121. This can be done either by having the thermostat send a signal relating to the temperature of the contents of said storage unit to the control unit 123 which then activates die element 121, or the thermostat can be partially or fully independent of the control unit 123. i The control unit can also act as a programmable timer, shutting down the heater unit and allowing the water in the storage unit and boiling unit to cool during periods of non—use (e.g. at night). The timer can be programmed to activate the heater unit at a specified time. For example, if the heater unit is used in an office environment, the timer can be programmed to activate the heater unit at a specified time before the office is due to open, so that the hot water is available as soon as workers arrive. ‘In the preferred embodiment, the timer settings can be adjusted via an auxiliary control system and timer (not shown), that are mounted on the casing 100. This allows a user to adjust the settings without opening or removing the casing 100.

A connection conduit 113 connects the upper storage unit 110 and the boiling unit 111.

The conduit 113 passes through the side wall of the upper storage unit 110, close to the top of the storage unit 110.. As shown in figure 10, in the preferred form the connection conduit 113 is bent or shaped so that the end 114, located inside the storage unit 110, faces upwards. That part of the length of connection conduit 113 inside the storage unit 110 is located towards the top of the storage unit 110, in approximately the top third. End 114 is theuppermost part of the connection conduit 113. This arrangement has a dual advantage: firstly, locating the end 114 of the conduit 113 at the top of the storage unit 110 facing upwards ensures that only the hottest I Water (at the ‘top of the storage unit 110) enters the conduit 113. Secondly, locating the conduit 113 at the top of the storage unit 110 ensures that heat transfer away from the water in the conduit 113 is minimised, as the conduit 113 will be in Contact with the higher temperature water at the top of the storage unit 110.

As described above, conduit 113 runs between the storage tank 110 and the boiling unit 111. Water from the storage unit 110 enters the boiling unit 111 via the conduit 113, and is therefore prc-heated to between 75—80°C. Due to the construction described above, there is minimal heat loss from the water in transit through the conduit 113. The water from storage unit 110 arriving in the boiling unit 111 is heated quickly and efficiently from the 75-80°C at which it atrixies, to the required higher set point temperature of 3°C below boiling point— i. e. 97—.98°C in preferred operating conditions (preferred embodiment temperature). This process is controlled by the control unit 123 on the outer casing 100, which receives signals from a boiling unit level probe (not shown) inside the boiling unit 111. The preferred form of boiling level probe sends three signals to the control unit: a first signal, or boiling unit depleted signal, which is sent when the level of the contents of the boiling unit 111 drops below 2.5 litres, a second signal, or boiling unit empty signal, which indicates an unsafe water level to activate the boiling element 122, and a third signal, which indicates that the boiling unit 111 is full, or that the content is at the required level. ‘When the control unit 123 receives the boiling unit depleted signal from the boiling level probe indicating that the level has dropped below 2.5 litres, the control unit sends instructions to a connection tap (such as a solenoid controlled tap or similar (not shown)) on conduit 113 to open. Simultaneously, the control unit 123 sends a signal to a mains supply tap (not shown) on the mains conduit 112 instructing the mains supply tap to open. The control unit 123 controls the operation of both the conneciion tap and the mains supply tap. Opening the mains supply tap causes additional water from the mains connection to enter the storage unit 110. This causes the contents of the storage unit 110 to overtop the end 114 of the conduit 113. As end 114 is located at the top of the storage unit 110, only the hottest water in the storage unit 110 enters the conduit 113 and passes through the connection conduit 113 into the boiling unit 11 When the boiling unit 111 is filled to its 2.5 litre capacity, the boiling level probe sends the boiling unit full signal to the control unit 123, indicating that the tank 111 is filled to the required level. The control unit 123 instructs the connection tap to shut in response to this signal. Water continues to flow through the mains supply tap into the storage unit 110 until the water pressure in the tank equals the inlet water pressure. The storage unit 110 contains a pressurestat or pressure switch (not shown) which operates by sending a signal to the control unit to close the main supply tap when the tank pressure exceeds the inlet pressure by 10%, and to open the main supply tap when the storage unit 110 water pressure drops below the inlet pressure.

The control unit 123 also controls the operation of the heater elements 121, 122. The control unit 123 receives signals relating to the temperature of the contents of the units 1 10, 111 and cycles the heater elements 121, 122 on and off as required to raise or rnaintain the temperature of the contents of the units 110, 111.

Water in the boiling unit 111 is stored at 3°C below boiling point uniil use — that is, at 97- 98°C under normal operating conditions - until use. The contents of the boiling unit is maintained at this higher temperature by Way of the heating element 122. Element 122 has the same power rating as element 121 used in the storage tank 110, and in the preferred embodiment is rated at 1.8 kW. The smaller size of the boiling unit 111 ensures that the contents can be heated to the required temperature very quickly. Heat losses from the boiling unit 111 are also minimised by use of the insulation 102, and the airgap 105. Boiling unit 111 includes a thermistor that monitors the temperature of the contents of the boiling unit and sends a signal to the controller to activate therboiling element 122 when the temperature “of the contents falls below a temperature close to boiling. ' A user or users draw off hot water as it is required, from the boiling unit 111 via a dispensing mechanism connected to the boiling unit 111. In the preferred embodiment at least part of the dispensing mechanism is a pump 120 in the side of the boiling unit 111. As the preferred embodiment of the water heater is intended to be located under a sink or similar, the pump 120 provides water via a dispensing conduit or similar to a user-activated tap or similar at bench top height, above the water heater. In the preferred form, the pump 120 is an electrically- controlled pump, of the type that are well—known in the art. When water is drawn off, the contents of the boiling unit 111 is immediately replenished by water from the storage unit 110, as described above. Usually, amounts of approximately ‘/2 litre at a time are drawn off from the boiling unit 111 for e.g. tea and coffee preparation. This accounts for roughly 20% of the total contents of the boiling unit 111. When this is replenished with 1/2 litre of water at approximately °C, the reduction in the temperature of the contents of the boiling unit 111 is not significant.

It has been found that the replenished contents can be brought back up to the required temperature of 3°C below boiling temperature (that is, between 97—98°C under normal operating conditions) very quickly. In terms of the operation of the water heater 101, bringing the contents of the boiling unit 1 11 back up to the required temperature is effectively instantaneous.

In the most preferred embodiment, water can also be drawn off from the storage unit 110 at the lower temperature of 60—70°C, if required for washing or similar. This water is drawn off via a dispensing conduit or a standard sink faucet, or si.tnila1:. Théidrawn off water is reduced from 80°C to 60-70°C via a balance valve 131 in the outlet of the storage unit 110 so as to prevent damage to seals, pipes and the such in the hot water lines immediately exiting the storage unit 1 10. i As described above, when storing water at a temperature above atmospheric (e.g. atmospheric temperature assumed to be approximately 30°C), there will always be some heat losses. There are two main heat‘ loss paths in the system described: firstly, heat is lost from the main storage unit 11Q through the insulation 102 and through the paths formed through the insulation 102 to allow the conduits 104 and control circuitry access to the heater unit 101.

Secondly, heat is lost Etom the b,oil.ing unit 11 1 via the insulation 102 and also Via conduction and convection to the storage unit 110. As there will always be some heat loss from both the storage unit 110 and the boiling unit 111‘, the configuration of the heater 101 is arranged to take advantage of this inevitable heat loss and minimise the associated problems. Firstly, the base’ 106 of the storage unit 110 rests on the rim 130 of the boiling unit 111. There is no direct contact between the base of the storage unit 110 and the top of the boiling unit 111, except through the rim 130. arrangement minimises the surface area available for heat conduction from the boiling unit 111 to the storage unit 110. ‘Secondly, the boiling unit 111, which operates at a higher temperature than the storage unit 110, is located below the storage unit 110. This ensures that heat lost from the boiling unit 111 via‘ convection in the airgap 105 is transferred upwards to the storage unit 110, as primary energy loss via convection is upwards. By configuring the heater units 110 and 111 in this way, at least part of the energy losses from the boiling unit 111 are transferred as energy gains to the storage unit 110.

By creating a system close to the design parameters outlined above (tank capacities and dimensions, a preferred upper temperature of water in the storage tank 110 of 80°C, an airgap size of approximately 10mm), the energy losses from the boiler unit 111 can be closely matched to the energy losses from the storage unit 110 (occurring via the insulation and the paths as described above), and can be used to compensate for the majority (e.g. 90%) of these losses.

With the temperature of the water in the storage unit 110 at the preferred temperature of 80°C, the energy losses from the storage unit 110 are almost completely compensated for by the heat transfer from the boiling unit 111 with the contents stored at 3°C below boiling point. The . boiling element 122 only needs to be cycled on and off approximately twice a minute to maintain the system 101 at this state. Any energy losses from the storage unit 110 that are not compensated for by convection and conduction effects are compensated for by cycling the storage element 121 .. This design and layout has been found to significantly increase system efficiency.

It can be seen that the size of the airgap 105 (controlling convection) and the nesting arrangement (controlling surface contact area and therefore conduction) are carefully tuned so that heat losses from the boiling unit are not critical, but that the inevitable heat losses are converted to benefit the overall system. It should also be noted that it is possible to vary these parameters to tune the overall system to achieve the sameresult. For example, the convex and concave surfaces could be manufactured with different curvatures, so that the size of the airgap varies from point to point across the two surfaces. Alternatively, the relative temperatures of the contents of the two units, or their relative dimensions, could be varied. This Variation of the parameters is tuning the system to achieve energy efficiency and reduce the necessity of cycling the heating elements to maintain the contents of the units at the desired level.

The user-operated tap referred to above, suitable for use with the heater unit described above, shall now be described in more detail with reference to Figures 6-11.

The overall form of the preferred embodiment of the user-operated tap is shown in Figure 6 as a single tap body or tap 200. The body of tap 20011213 three main parts: a hollow vertical stem 201 that in use is mounted to a surface such as a bench top or as shown in Figure 7, and two branches that split from the top of the stern 201 and which are angled slightly upwards so that the tap body has the overall form of a T— or Y-shape. The branches of the preferred form are angledislightly upwards from the horizontal. It should be noted that the tap 200 could be adapted for mounting to any suitable surface or point, such as a wall, pillar or similar. One branch of the Y~piece (the lever arm 220) includes a pair of user operated lever bodies 202, 203 that form the end of the lever arm 220. A user can manipulate the lever bodies 202, 203 by pulling them up or pushing them downwards. Pressing one of the lever bodies downwards activates the tap and causes water to be dispensed eg. from the boiling unit 1'11, or from another source such as a water chiller (not shown), depending on which body is depressed.

The second branch of the Y-piece (main body 221) has. a dispensing nozzle 204, located at the end and on the underside of main body 221, facing downwards.

An exploded view of the tap 200, showing the main sub—parts, is shown in Figure 8. A ' set of silicon tubes 205 is located inside the vertical stem 201 to carry water from the boiling unit 111, and the water chiller (not shown). The inner ends of the silicon tubes 205 are connected to the inner ends of a complimentary set of copper pipes 206, which run from the junction of the Y-piece to the nozzle 204, inside the main body 221. The silicon tubes 205 and the copper pipes 206 together form a tap conduit, with the free end of the silicon tubes 205 connected to the end(s) of the dispensing conduit running from the boiling unit 111. In the preferred embodiment . a conduit runs from the storage unit 110 also, and is connected to one of the silicon tubes 205.

A base flange 207 is included in the preferred embodiment to aid mounting of the tap 200 to a mounting surface such as a bench "top. The lever bodies 202, 203 are included as part of a lever subasseinbly 210 that connects to the tap 200, the subassernbly 210 forming part of both the stem 201 and the lever arm 220. A safety button 218 is included inthe structure of the tap 200. The safety button 218 acts as an electricalswitch. When it is activated, it stops inadvertent operation of the lever bodies 202, 203, thereby preventing accidental spillage of boiling water.

The preferred form of the lever subassembly 210, and the operation of the lever bodies 202, 203 is described in more detail below, with reference to Figures 9~1 1.

An exploded view of the lever subassembly 210 is shown in Figure 9. In the preferred embodiment,- the lever subassembly 210 includes the following main parts: a rear cap 211, two lever bodies 202, 203, two lever arms 212, two lever springs 2'13, and a sensor board 214. l The lever bodies 202, 203 include a set of end caps 208, 209 that are pressed into recesses in the tops of the bodies 202, 203 during assembly. These ends caps 208, 209 can be differently coloured as required by a user — e.g. one end cap can be coloured red to show that activating that lever body causes the tap 200 to produce hot water at a temperature close to boiling point (water from the boiling unit 111).

The rear cap 211 is generally L-shaped (the ‘L’ is inverted in use). When assembled, the rear cap 211 attaches to, and forms part of,_the tap 200, with the outer surfaces of the rear cap 211 lying flush with the main body of the stem 201 and the lower part or underside of the lever arm 220. The rear cap 211 includes pivot recesses 216 on its upper surface, the upper surface being located inside the body of the tap 200 in use. When the tap 200 is fully assembled, pivot projections 217 on the lever arms 212 locate into these pivot recesses 216, allowing each of the lever arms 212 to pivot around the pivot recesses 216, independent of each other and also independent of the rear cap 211. On the outer side of the pivot projections 217 (that side furthest away from the Y—junction), the body of each of the lever arms 212 extends outwards to form a projection 219. Each of the lever bodies 202, 203 includes a complimentary recess so that the lever bodies 202, 203 can locate onto these projections 219 in use. The lever arms 21?. and the lever bodies 202, 203 move as one unit when assembled. These parts do not move relative to one another. Where reference is made in this specification to a ‘first part’, this should be understood as referring to a part of the assembly that includes at least that part of the lever arm 212 on the outer side of the pivot projections 217, and which preferably also includes the attached lever body (either 202 or 203). I On the inner side of the pivot projections 217, the body 223 of each of the lever arms 212 extends outwards and curves downwards so that when the tap 200 is assembled, the body 223 angles downwards into the stem 201. Where reference is made in this specification to a ‘second part’, this should be understood as refernng to at least that part of the lever arm 212 on the inner side of the pivot projections. When the lever arms 212 are rotated around the pivot recesses 216, the inner ends 224 of the lever arms 212 describe a short are inside the stem_201. A _ magnet 225 is attached to each of the ends 224.

Sensor board 214 is a PCB board which is located inside the stem 201 in use, and forms at least part of a sensor assembly. The sensor board 214 is oriented so that it runs across the width of the stem. 201, in the same orientafion or plane as _the ‘Y’ of the tap 200. One edge of the board 214 locates into a slot 229 in the rear cap 211 to hold the board 214 in position. A of sensors is located on each side of the board (four sensors in all, two on each side). The board, sensors and the lever arms 212 are sized and located so that when the tap 200 is assembled, each pair of sensors is located at opposite ends of the short arcs described by the ends 224 of each of the lever arms 212. One pair of sensors — 226, 227, located on one side of the board 214, is shown in Figure 9 and Figure 11.

The sensors 226, 227 are magnetically sensitive. As the corresponding magnet 225 describes the short are in response to movement of the lever arm 212, as outlined above, the sensors 226, 227 respond. It can be seen that the location of the magnet .225 directly corresponds to how far the lever body 203 has been depressed. As the magnet 225 moves, the sensors 226, 227 send a variable signal to the control unit 123, the signal varying depending on the position of the lever arm 212, and corresponding to the position of the magnet 225. The control un.it_123 activates and cycles pump 120 depending on the signal. For example, if a user requires hot water from the boiling unit 111, they depress the appropriate lever body — e.g. lever body 203. When lever body 203 is depressed, this moves magnet 225 away from the off position, close to sensor 226, and towards sensor 227. The movement of the magnet causes the sensors 226, 227 to send the variable signal to the control unit 123, indicating that lever body 203 has been depressed. The signal will vary depending on how far the magnet 225 has been moved.

When the control unit 123 receives this signal, the control unit 123 activates the pump 120, which pumps water from the boiling unit 111 through the tap 200 to the nozzle 204. The variable signal allows the control unit to vary the activation of the pump 120, and therefore the volume of the flow through the pump 120 and the tap 200 can be varied depending on how far a user has depressed the lever body 203. It should be noted that although one sensing mechanism has been described above, any appropriate sensing mechanism could be used if required.

When the tap 200 is not in use, and the lever bodies 202, 203 are not depressed, or immediately after use when the lever bodies 202, 203 are returned to a position where they are not depressed, the corresponding sensors are either inactive (or they are deactivated as the lever body returns to this position). Alternatively, the sensors can send a signal to the control unit 123 indicating that the lever body or bodies (and therefore the magnets) are in an ‘off’ position. The control unit 123 responds by deactivating the corresponding pump or pumps _(i.e. if lever body 203 is depressed, signals are sent to control unit 123 from sensors 226, 227, and the control unit activates pump 120. When lever body 203 returns to a non—depressed state, the control unit deactivates pump 120). A similar arrangement can be used if chilled water has been requested from the water chiller (not shown).

In the preferred embodiment, the lever bodies 202, 203 are sp1ing—loaded so that when they are not actively depressed by a user, they automatically return to the default, non-depressed position. The preferred Form of spring loading shall now be described.

The lever subassembly 210 includes a pair of lever springs 213, one for each of the arms 212. The lever springs 213 generally have the form of leaf springs or flat springs, with a flat central body portion, a 180° hook or bend 232 at the inner end and a 90° hook or bend 233 that includes a kink 235 at the outer end. Each of the lever arms 212 has a central portion 230 shaped so that the 180° hooked end 232 can hook onto or slide over the central portion 230. The shaped central portion 230 is located so that when the springs 213 are in position, the centrepoint of the hook 232 corresponds to the centre of rotation of the lever arm 212. The outer end 233 of each of the springs 213 is shaped to engage with tabs or projections 234 on the rear cap 211, the kink 235 ‘clicking’ over the projections so that the spring 213 is held in place. I When either of the lever bodies 202, 203 is depressed, the corresponding attached lever arm 212 will rotate. The rear cap 211 is connected to the tap 200 and remains stationary, so the central body portion and the outer end 233 of the corresponding spring 213 will also remain stationary. However, as the lever arm 212 rotates downwards, it presses against the underside of the 180° bend 232 and rotates this portion of the spring 213 downwards and inwards towards the body of the tap 200. The spring 213 will deform as the outer end 233 is held in position. As the spring 213 is bent in this manner, it exerts a reaction force on the lever arm 212. When the user removes pressure from the lever body, the reaction force from the spring 213 causes the lever arm 212 and the lever body to return to the non-depressed position. \‘<’/'hcn either of the lever bodies 202, 203 is pulled or rotated upwards from the first or off position, the corresponding attachtd lever mm 212 will rotate. The rear cap 211 is connected to the tap 200 and remains stationary, but the central body portion and the end 233 of the corresponding spring 213 are attached to the lever arm 212 and rotate freely with it. As the leveit arm 212 rotates upwards, end 233 and the kink 235 deform over the tab or projection 234 aliowing the lever arm 21?. to dctcnt and remain in the up position. The user must then push the lever back down to re-set it into the first or off position. The tap will t}.1cr(:f<.>rc: remain on until the user p11ShES the cap back to due central rest position.

The. lever suhzissr-=mb]y 210 aisr.) includes :3 safety board 215. In the pr:~fet'red embodiment, this is connected to the safety button 218. The safety button 218 is used to activate or dc::{tCCiV2‘(t’L“, thc mp 200 activating or dcactivzitiiig the pump 120). Li3D’s on the safety‘ board protrude through the top surface of the safety button B8. These LED’s indicnze the status of the switch (locked or unlocked) to :1 user, and also indicate the readiness of the dual chamber water heater, and the perfnrinzmce of any other items in use with the system, such as n Wat‘:-;*.1: filter.

It should aiso be noted that the mp 200 described above could be used, or can be adapted for use with, other types of h an xvnter heater other than the one described in the p1'cfv.':1*rcd embodiinent. The tap 200 could also be used ind.cpcndent].y with other water sources if required, for example by connecting it to a mains conduit.

Claims (29)

Claims

1. '1. A water heater for providing hot water to 21 user, comprising: :1 storage unit. adapted to hold 21 first volume of water, and lmving :1 mains conduit aclzipted For. cnnnectinn to a mains water supply so that said smtzige unit mm receive water from said mains water. supply, said storage unit also having a storage limiting element adapted to he: and maintain said flrstvoiu-mu: of'\VaLe1' :11. an intermediate tcinpemture bctiveexi room temperature and boiling point in use, a boiling unit, adjoining said storage unit and adapted to hold a second volume of water and having :1 boiling heating element adapted to hear and maintain said second volume of water at :4 high tempemtute in use, said boiling unit also having a dispensing mechanism adapted to allow 3 user to draw offwatcr from said boiling unit, a connection conduit, running between said smmge unit and said buifing unit‘, so that in use said boiling unit can receive water from said sto rage unit, said boiling unit and said storage unit directly adjacent or adjoining one another and separated by an airgap, said storage unit incated above said boiling unit, wherein the base of said storage unit is EL convex surface, and the top of said boiling unit is a concave surface, said base adjacent to said top.

2. A water heater as claimed in claim I wherein the curvature of said convex surface snissmnfialiy matches the (1111-variirct nf said concmze siirfiice so that the size of said airgap is the same size over a substzxntiiil portion of said concave and convex surfaces.

3. A water heater as claimed in claim 1 or claim 2 wherein said dispensing mechanism comprises a pump, in fluid communication with the contents ofsaid boiling unit.

4. A water heater as ciaimed in claim 3 wherein said dispensing mechanism further comprises :1 dispensing conduit, one end of said dispensing conduit fluidicaily connected to said pump to receive said water. from said boiling unit Vin said pump, the other end of said ccmduit adapted fox: connectioii to a usc1'—opemted tap.

5. A water heater as clnimmi in any (me mi’ claims 1 ‘m 4 wherein the relative cnpziciry and dimensions of said stoxtage unit and said boiling unit, the relative curvatures of said concave and convex Stl1ff'ACCS, and tin: size of said airgap, are calculated so that heat transfer to the storage unit from the boiling unit compensates for heat iosses from the storage unit to the surrounding environment.

6. A water heater as claimed in any one ofclaims 1 to 5 wherein said airgap is between (imm and 15mm.

7. A wat.e1:I1e:1r.er as claimed in claim 6 whcmin said air a 3 is suhst;mti:1.ll' 9mm. *5 I l

8. A w:ite1'l.1earei' as claimed in any one Of claims 1 to 7 wherein the c:1p:acity of said storage unit is between '10 and £4 litres, and the capacity of said boiling unit is between 1.5 and 3.5 litres.

9. A water he-:1te.t as claimed in claim 8 wherein the c::pac.ity of said storage unit is SLKiJSf1i.I1{‘.i€1i.lY 12 litres, and the capacity of said boiling unit is substarltialixr 2.5 litres.

10. A xvater heater as Claimed in any one ofclitims 1 to 9 wherein said intcnnediate storage tenipcrmure is between "X0-~‘)U°C.

11. ll . A water heater as claimed in any one of claims '1 to 9 wherein said imetmcdizne storzagc: temperature is :1 set point teinpcrz-xturc of substantially B0"C.

12. A water heater: as claiined in any one (if claims '1 to 1 1 wh.eI.'ein said boiling unit further (‘.0l1'lpY‘lS.(*.S a rim, aligned 5I.ll_‘l:-‘-t7lflfl5lil]? vertictally and running around or close in the top eiige nf said boiling unit, said storage unit testing on said xzim in use.

13. A water heater as claimed in any one of claims I to 12 wherein said storage unit and said boiling unit are circular in plan view, each hzuring a cliame rat in the region of 27cm.

14. A water licziter as claimed in any one of claims 1 to 13 wherein when said storage unit and said boiling unit ate assemblecl to forin part of said water heater, their combined height ‘(mm the base of said boiling unit to the top of said storage unit is in the region of 40cm.

15. A water heater as claimed in any one of claims I to 34 wherein said water heater further comprises A casing, said storage unit and said boiling unit located within said casing in use, said vs.~'ate1- heater further comprising insulating material, the space between said water healer and said casing Filled with said insulating inamrial, so that said iiisulatiiig material surrounds and fully encloses said storage unit and said boiling unit.

16. '16. A water heater as claimed in claim 15 said insulating material is formed as two separate expanded polystyrene pieces that together form an insulating shell that encloses said water h€5flI€l'.

17. A water heater as claimed in any one of claims 1 to 16 wherein said boiling heating element is adapted to licat and maintain said St.CE)1‘1Cl".'0l'u1‘!1t‘:0f\.V:1tC£ at 21 temperature of1':et1wccn

18. l-\. wzitizr. heater. as claimed in any one of claims 1 to 17 wlierein said boiling heating &°‘l.{‘n71(-‘.13! is aciapteci to heat and maintain said sectmd voluine of water at :1 re-mperamre of 3°C below boiling point.

19. I‘). A water heater as claimed in any one of claims 1 to 18 wherein said boiling heating ck-inent has :1 power output in the rcgimi of1.8 k\Y.=".

20. A water licater as claimed in any one of claims l to 19 wherein said storage tslcment has it powct output in the 1'4-:gi0n of 1.8 kW.

21. A warm hentct as claimed in any one of claims 1 to 19 wherein at least part of the length of said COI111cCtl(.)1’1 conduit is located in said storage unit, sublnerged in the upper third of the contents of said storage unit in use.

22. A waiter limiter as 4.:l:1ime:d in claim 21 wl1c1:cin that cud of said CU111Ii;:(.‘liL.)I1 cumluit iliztl is located in the storage unit faces upwatuls, and when said storage unit is filled to the required level, said end is just below the surface of said first volume of water.

23. A water heater as claimed in m1_\_-' one of claims 1 to 2?. wherein said storage unit. ftuctlicr coinpriscs a dispensing conduit adstptcd for c0nncc'u'c-n to a tap to enable a user to draw off water from said stetagc unit, said storage unit having an outlet, said dispensing conduit connected at said outlet, said storage unit also having a balance valve located at said outlet, said balance valve adapted to cool water exiting said storage unit to a maximum temperature of 70"('L.

24. A water heater as claimed in any one of claims 1 to 23 whcrcin said water hcatcr further comprises :1 control unit adziptcd tu receive signals from pmbcs and switches in said water hciitcr, and tratxsmit iI1StrUCt“i()I1 signals accotding to pre-progmmming, and said storage unit further comprises :1 pressure switch adapted To send a storage unit full signal to s2.i.d control unit when said storage unit is l"1'll.t~:<_i to the .requirt=.d pressure, and a storage unit depleted signal to said ctmtrol unit wht:.r1 said storage unit is not filled to said xzequited pressure, said boiling unit further. comprises a boiling level probe fu;l'E11) ted to send :1. boiling unit full signal to said cotlttol intxclmtiism Wl1t:Il said boiling unit is filled to the rcquii-4:-Ll boiling lwcl, and a boiling unit depleted signal to said contml uuit \h’lIK3Il said boiling unit is not filled to said requiretl boiling level, mini mains cnnclaiit fnrtlu-r mmprising a mains supply tap, said cm1t.rr>l unit sending instructitm signals to said nmins supply tap to control said rnzlius supply tap, said Coi1i1ccti<.)n conduit l"u1:tl1c:1' comprising 51 connection mp, szticl control unit scnding instruction signals to said connection tap to control said connection mp, said boiling level probe sending said boiling unit depleted signal to said control unit when \V51t(t1‘ is drawn off from Said boiling unit via said dispensing mechanism, said control unit instructing said coimectioti tap and said mains supply tap to open in response to receiving said boiling unit depleted signal, said storage unit receiving additional water from said mains conduit, said additional water displacing at least part of said first volume of water and causing part of said first volume. of water to pass into said boiling unit via said connect-ion conduit, said boiling level probe sending said boiling unit full signal to said control unit when said boiling unit has been refilled, said contrnl unit instructing said cmmecrinn tap to t:.lnse in resprmnscs tn recciviiig said boiling unit full signal, said storage pressure scissor sending said storage unit full signal to said cmitrul. unit when said storage tank has been refilled, said contizul unit instructing said mains supply tap to close in response to receiving said storage unit full signal.

25. A water heater as claimed in claim 24 wherein said storage unit furtlicr comprises a thermostat, s-aid tlxcttnostat activating said storage element when the tetnpetnmm of the contents of said storage unit falls below 21 set point temperature level of substantially 8()"C.

26. A water. heater as claimed in claim 24 wherein said storage unit. further comprises a thermostat adapted to send a signal relating to the teinpemture of the contents of said storage unit to said control unit, said control unit activating said storage element when the tempm-nture nf tlm contents of said storage unit drops below :2 set storage unit temperature.

27. A water hunter as claimcd in any out: of claims 24 {o 26 whcrcin said builing unit fu1‘thc:r comprises a thermistor, said thermistor activating said boiling heating element when the tempcmture of the contents of said boiling unit drops b clmv a set boiling unit temperature.

28. A water heater as claimed in any one of claims 24 [O 26 wherein s:1idboi1.ing unit further comprises a tlnctmistor, said thermistor sending 21 signal relating to the tn-zmpctaturcs of thc contents of said boiling unit. to said cormol unit to activate. said boiling heating element when the temperature of the ccmtcnts of said boiling unit. drops below a set boiling unit temperature.

29. A water heater as claimed in claim 27 or claim 28 wherein said set boiiing unit tcmpcmturé is 95°C.