GB2483990A

GB2483990A - Fluid heater system

Info

Publication number: GB2483990A
Application number: GB1116254.2A
Authority: GB
Inventors: Donald Leonard Webb
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-09-24
Filing date: 2011-09-20
Publication date: 2012-03-28
Also published as: GB201116254D0; GB201016089D0

Abstract

A fluid heater has a container (1, fig.1), a fluid input 23 and a fluid output 24. A thermostatically controlled diverter valve 7 is provided including an input port 8, and first and second output ports 9, 10. The diverter valve has a thermally sensitive part 29 arranged to be in thermal communication with fluid at the input port. If the temperature of fluid arriving at the input port from a source conduit 42 is below a predetermined temperature the fluid is directed out of the first output port 9 into a lower portion 1A of the container, but if the temperature of fluid entering the input port is above a predetermined temperature, it is directed to the second output port 10 to downstream. A heater 11 is arranged to heat fluid in the container and means 41B are provided so that fluid in the container is in fluid communication with the fluid output such that when fluid is introduced into the container from the first output port fluid is forced from the container through the fluid output to downstream. The heater is controlled in response to the temperature of fluid in the container buy switch means (12, 52; fig.10).

Description

FLUID HEATER SYSTEM

The present invention relates generally to a fluid heater and more particularly to a shunt water heater for providing near instant hot water at the point of use where the point of use is situated at some distance from the primary source of hot water so as to achieve environmental benefits through water and energy saving, Typical points of use would be taps at kitchen sinks, taps at washbasins, bidets, baths, or shower fittings. As described in US Patent No. 4,321,943, No. 4,798,224 and No. 5042524, the primary hot water source for such user points is often a hot water storage tank situated at some distance away from the user points in another part of the building. This leads to delays and quantities of wasted water as the cold water held in the interconnecting source conduit needs to be run off until the following hot water reaches the user point. Over a period of time considerable delays and waste of water and energy, from heat losses, can arise from repetitive operations of user points after intervals long enough to allow the water held in the interconnecting source conduit to cool down. It is understood that the primary hot water source may be a combi-boiler.

Prior art solutions include the installation of a return conduit loop and pump to facilitate recirculation of fluid to and from the primary hot fluid source.

US Patent No. 5042524 describes such a system. However, the amount of energy loss through heat dissipation from a double run of conduit, the additional installation costs, and the difficulty in retrofitting these systems in established buildings detracts from possible advantages.

According to the present invention, there is provided a shunt fluid heating unit which, when installed in the interconnecting conduit run between the primary hot fluid source and, near to, at least one user point, is capable of providing an amount of hot fluid on demand equal to, or greater than, the fluid holding capacity of the conduit interconnecting the primary hot fluid source with the shunt fluid heater.

Any cold fluid in that interconnecting conduit is shunted by a thermostatically controlled diverter valve (TDV), which may be embodied internally or externally, into the heating zone of the shunt fluid heater where it is heated in readiness for the next time it is demanded. As soon as the fluid arriving from the primary source rises above a predetermined temperature, the thermal sensor of the TDV activates the TDV to restore the direct conduit interconnection to the user point or points.

According to one embodiment of the invention there is provided a shunt fluid heater comprising: a container; a fluid input and a fluid output; a thermostatically controlled diverter valve (TDV) with an input port, a first output port and a second output port, a thermally sensitive part in thermal communication with fluid at said input port such that if the temperature of fluid arriving at said input port from a source conduit is below a predetermined temperature it is directed out of said first output port into a lower portion of said container, and if the temperature of fluid entering the said input port is above a predetermined temperature, it is directed to the second output port and then to downstream use; fluid communication means between the container and the fluid output such that when fluid is introduced into the container from the first output port fluid is forced from the container through the fluid output for downstream use; a heater to heat the fluid in the container; and switch means for controlling the heater in response to the temperature of fluid in the container such that the heater is switched on when the temperature of fluid in the container falls below a predetermined temperature, and is switched off when the temperature of fluid in said container rises above a predetermined temperature.

According to at least one embodiment of the present invention the TDV is a mechanically activated valve wherein the thermally sensitive part is a thermally sensitive capsule generally as described in US Patent No. 5188287, but more specifically as used in conventional Thermostatic Mixing Valves.

It is understood that the thermostatically controlled diverter valve (TDV) is similar in construction to at least one proprietary Thermostatic Mixer Valve (TMV), but the fluid flow through a TMV is in the opposite direction to that of the fluid flow in a TDV. The function of a TMV is critically to adjust the position of a sleeve to determine the admixture of hot and cold fluids arriving via two input ports from a hot fluid source and a cold fluid source respectively, and to deliver the admixture through a single output port. In contrast, the function of the TDV is to sense the temperature of fluid arriving via a single fluid source at a single input port, to determine the temperature of that fluid and to direct that fluid to one of two output ports depending upon whether or not the temperature of the arriving fluid is below or above a predetermined temperature.

In at least one other embodiment of the present invention the TDV is activated electrically by a solenoid or motor.

Means of heating may be provided by a kettle type heating element or an immersion heater, the switching of which is controlled by a thermal sensor via a control circuit and which is disposed such as to sense the temperature of the fluid within the container of the heating unit. It is desirable that the thermal sensor is disposed low down within the container so that the element is turned on as soon as possible once the cold fluid begins to enter the heating unit.

Furthermore, it is desirable that the rating of the heating element is chosen so as to be capable of restoring the availability of sufficient hot fluid in the heating unit in a reasonable time. Therefore, consideration should be given to several factors including the cooling-off period of fluid held in the interconnecting source conduit, the fluid holding capacity of said conduit, the fluid holding capacity of the heating unit, the efficiency of the heating unit, the heat losses from the container of the heating unit and the limitations of the electricity source. The addition of suitable external insulation material helps to reduce the heat losses from the container to a negligible level.

In the prior art, US Patent Publication No. 20080302315, it is recognised that the in-flowing cold fluid arriving at a fluid heater can impair efficiency of the heater as the cold fluid mixes with the preheated fluid because of the resultant turbulence and admixture. The efficiency, in terms of the amount of hot fluid available relative to the overall size of the container, each time hot fluid is drawn from the shunt fluid heater, is an important factor when determining the size of the shunt fluid heating system best suited to a particular installation. For example, if the capacity of the interconnecting source conduit, between the primary hot fluid source and the shunt fluid heater, is 3 litres, and the shunt fluid heater is 50% efficient, then a shunt fluid heater of at least 6 litres capacity would be required, excluding any such capacity as may be contained in a cavity below a partition plate (discussed in more detail below).

In at least one embodiment of the present invention there may be provided means for controlling turbulence caused by fluid entering the container. The means may be a perforated partition plate characterised by a plurality of openings, or alternatively may be a perforated cap characterised by a plurality of slots through which fluid from the first output port is directed upon entry into the container. The perforated cap may be cylindrical in shape, or may be any other shape which is capable of having slots formed therethrough.

According to at least one embodiment of the present invention there is provided a kit for installation of a fluid heater, the kit comprising a fluid heater as defined herein; means for connecting a hot water supply pipe to the fluid input and to the fluid output of the fluid heater so that the fluid heater can be installed directly into the supply pipe; and means for connecting the fluid heater to an electrical supply for the supply of electrical energy to the heater and to the switch means. In this way the self-contained shunt fluid heater may be deployed as a stand-alone unit, connections to the local plumbing being achieved by screw-on flexible hoses, with the electrical supply being derived from a thirteen amp ring main. In this embodiment the diverter valve is contained within the container which need only be connected into the hot water supply pipe.

The predetermined operating temperature setting of the TDV may be adjustable. To facilitate such adjustment, a spindle may be provided which extends from the TDV, and which passes through the wall of said container via a fluid-tight gland to an external adjustment facility.

The thermostatically controlled diverter valve may be external to said container or contained within it.

The thermostatically controlled diverter valve may be an internal or external mechanical device in which said thermally sensitive part is a component that alters in shape or size in response to changes in temperature, and which is coupled to the valve element. Alternatively said thermostatically controlled diverter valve may be an external electrically activated valve. This may be a conventional solenoid or motorised diverter valve characterised by a mechanical change-over valve actuated by an electrical solenoid or motor, said solenoid or motorised valve being in electrical communication with a thermal sensing fitment. In either case, when fluid arriving at the said input port is below a predetermined temperature or above a predetermined temperature, fluid is directed out of said first output port or out of said second output port respectively.

Said heater may be disposed in a lower internal portion of said container.

The thermal sensor that controls the heater may also be disposed in said lower internal zone, but away from said heater.

Preferably said container is thermally insulted. This may be by any means such as a double skin having a vacuum within the said double skin, or by an external jacket.

The present invention is primarily intended for heating water so preferably the shunt fluid heater is a shunt water heater.

The present invention also provides a kit of component parts prior to assembly comprising the component parts for at least one shunt fluid heater as defined herein.

The invention will now be described solely by way of example with reference to the accompanying drawings in which: Figure 1 shows a perspective view of a shunt fluid heater with part of the container cut-away and no external insulation jacket fitted.

Figure 2 shows a view of a shunt fluid heater from direction "Z" with container, partition plate, gasket, and external insulation jacket, in cross-section, with enlarged cross-sectional views of an external adjustment facility and a bleed valve.

Figure 3 shows a view of a shunt fluid heater looking down on cross-section "X" -"X" with no external insulation jacket.

Figure 4 shows a view of a shunt fluid heater from direction "Y" with container, partition plate, gasket, and external insulation jacket, in cross-section, with an enlarged cross sectional view of a thermal sensor.

Figure 5 shows a simplified view of a typical mechanical thermostatically controlled diverter valve with body, sleeve, spokes and spring in cross-section.

Figures 6A and 6B show simplified diagrams of the fluid flow for an internal diverter valve in the "shunt" position and in the "direct" position respectively.

Figure 7 shows a view of a shunt fluid heater with an external thermostatically controlled diverter valve, from direction "Z" with the container, partition plate, gasket, and external insulation jacket, in cross-section.

Figure 8 shows a plan view of a perforated partition plate.

Figure 9A and 9B show simplified diagrams of the fluid flow for an external diverter valve in the "shunt" position and in the "direct" position respectively.

Figure 10 shows a simplified diagram of the electrical connections.

Figure 11 shows a diagram of a typical electronic thermostatic control circuit.

Figure 12 shows a view in part cross-section of a perforated cylinder cap wherein fluid enters from above.

Figure 13 shows a view in part cross-section of a perforated cylinder cap wherein fluid enters from below.

It is to be understood that the Figures are not necessarily to scale but have been drawn to simplify an understanding of the present invention.

Referring to the Figures, there is shown a container 1 which may be generally cylindrical (shown) or generally rectangular, preferably square (not shown) in the horizontal plane, comprising an assembly of a bottom part IA having a flange 37 at the top rim, a top part I B having a corresponding flange 38 at the bottom rim, means for sealing said flanges, which may be an interposed compliant seal or gasket 39, the flanges and the seal being held together by means of a plurality of fixings 4, which may be bolts 6 and nuts 5, an input fitment 23 and an output fitment 24.

A thermostatically controlled diverter valve 7 is disposed inside the container 1, and is characterised by a casing 78, an input port 8, a first output port 9, and a second output port 10, coaxially related pre-adjustment facility 31, piston 86, sleeve 27, central support 87, a plurality of spokes 79, thermostatically sensitive part 29 which is expandable and contractible when subjected to increases and decreases in temperature respectively, which may be a conventional "wax capsule", spring 36, a cylindrical guide 85, end stop 84, end stop face 80, porch stop face 81, end gap 82, and porch gap 83. The thermally sensitive part 29 is in thermal communication with fluid arriving at the input port 8, via interconnecting conduit 41A. The fluid, arriving under pressure from fluid source 40 via conduit 42, causes the thermally sensitive part 29 to operate so as to determine the position of the sleeve 27 within the cylindrical guide 85.

When fluid arriving under pressure at the input port 8 via interconnecting conduit 41A and source conduit 42, is below a predetermined temperature (i.e. "cold") as determined by the setting of the pre-adjustment facility 31, piston 86 recedes into the body of the thermally sensitive part 29 allowing the spring 36 to indirectly force the sleeve 27 into contact with the end stop face 80, thereby closing end gap 82. This allows fluid to pass through the porch gap 83 and out via the first output port 9 which is in fluid communication with the lower internal zone 35 of the container 1. The pressure of the fluid is such that fluid is forced from the upper internal zone 34 of the container I into the interconnecting conduit 41B, which is in fluid communication with the output fitment 24, via which fluid passes to the delivery conduit 44 and at least one user point 45.

Correspondingly, when fluid arriving under pressure at the input port 8 via interconnecting conduit 41A and source conduit 42, is above a predetermined temperature (i.e. "hot") piston 86 extends out of the thermally sensitive part 29 forcing the sleeve 27 to move in opposition to the force of the spring 36 and to force the sleeve 27 into close contact with the porch stop face 81. This closes porch gap 83, and allows fluid to pass between the spokes 79 of the sleeve 27, through the end gap 82, and out via the second output port 10 which is in fluid communication with the output fitment 24, via the interconnecting conduit 41 B. The central support 87, sleeve 27, spokes 79, and the thermally sensitive part 29 may be integrally assembled. The piston 86 is able to slide coaxially through the centre of the central support 87 into the thermally sensitive part 29. A fluid seal between the thermally sensitive part 29, and the piston 86, is achieved with the provision of a flexible membrane (not shown). Fluid seals 88, 89, 90, are provided which may be conventional "0" rings.

Fig.5 shows the thermostatically controlled diverter valve 7 with the sleeve 27 in a transitional position with neither the end gap 82 nor the porch gap 83 closed. Figs. 6A and 6B show simplified diagrams of the fluid flow from fluid source 40 to user point 45 for when the end gap 82 is closed and for when the porch gap 83 is closed respectively.

The pre-set adjustment facility 31 is set to the predetermined operating temperature of the thermostatically controlled diverter valve 7 by determining the position of the end stop 84 which has the piston 86 forced into contact with it by the spring 36. The pre-set adjustment facility 31 may be adjusted manually prior to assembly or preferably at any time after installation by the provision of an external adjustment facility 30 and extension spindle 70 which passes through the fluid-tight gland 71 which may be rendered fluid-tight by a conventional "0" ring 32.

For a domestic water supply installation a typical predetermined operating temperature for the thermostatic diverter valve 7 would be between 35°C and 45°C whichever is desired, assuming a normal source water temperature of greater than 50°C.

An electrical heating device 11 is provided for heating fluid in container 1, which may be a conventional electrical "kettle" type element 11 (shown) preferably disposed to one side in the lower internal heating zone 35 of container 1. There is provided means for switching the heating device 11 on and off comprising a thermal sensor 12, which may be a thermistor in housing 13, for sensing the temperature of the fluid in the container 1, and a thermostatic control unit 52 which may be of a conventional type, a typical example of which is shown in Figure 11. The thermal sensor 12, the heater 11 and control unit 52 are in electrical communication so that the heater 11 is switched on when the temperature of fluid in the container I falls below a predetermined temperature, and is switched off when the temperature of fluid in the container 1 rises above a predetermined temperature. The predetermined temperature may be determined by a potentiometer type control facility 53.

For a domestic water supply installation a typical predetermined operating temperature for the thermostatic control unit 52 would be between 40 and 50°C whichever is desired.

In at least one embodiment of the present invention a bleed valve 14 is provided in order to release air trapped in the container. This is disposed in the roof 26 of the container 1 and may be a conventional bleed valve characterised by a body 16 and a removable screw 15 which may be loosened to allow air to escape.

The first output port 9 is open ended and in close proximity to the floor 25 of the container 1. The spacing 66 between the first output port 9 and the floor of the container 1 is such that were the cylindrical conduit, defining the output port, to occupy that space the surface area of the conduit that would have been in that space would be approximately equal to, but not less than, the cross-sectional area of the bore of the interconnecting conduits 41 so that fluid can flow freely into the lower internal zone 35 of the container 1. Fluid is forced from the upper internal zone 34 into the open end 68 of the interconnecting conduit 41B, the space 67 between the open end 68 and the roof 26 of the container being such that were the cylindrical conduit, defining the open end 68, to occupy that space the surface area of the conduit that would have been in that space would be approximately equal to, but not less than, the cross-sectional area of the bore of the interconnecting conduits 41.

In at least one embodiment of the present invention, wherein the thermostatically controlled diverter valve 7 is internal, there is provided a means of controlling the aforementioned turbulence by the provision of the aforementioned first method, which means incudes a perforated partition plate to control turbulence caused by fluid entering the container 1. The perforations are a plurality of openings 57, which may be elongated slots (shown), distributed evenly, preferably radially relative to the hole 58, over the area of the partition plate 60. Each opening 57 is substantially narrow relative to the diameter of the bore of the interconnecting conduits 41, the total combined cross sectional area of openings 57 being substantially greater than the cross-sectional area of the bore of the interconnecting conduits 41. The partition plate 60 generally extends to the full horizontal cross section of container I creating a cavity 59 below, but need only be a touch fit with the container I at its edges, such minor leakage as may result only contributing to the general effect of the openings 57. The perforated partition plate 60 has a hole 58 to co-operate with the first output port 9 such that fluid is directed from the first output port 9 of the thermostatically controlled diverter valve 7 to the cavity 59 below the perforated partition plate 60 so that fluid rises through the openings 57 from the cavity 59. The partition plate 60 being preferably spaced from the floor 25 of the container I by an amount such that were the cylindrical conduit, defining the first output port 9, to occupy that space, the surface area of the conduit that would have been in that space would be approximately equal to, but no less than, the cross-sectional area of the bore of the interconnecting conduits 41. The partition plate 60 may be supported by a plurality of pillars 62 (two of four shown) located at a plurality of holes 64 (four shown) in the partition plate 60 and holes (not shown) in the floor 25 of the container 1 and which may be held in position by a plurality of fixings 63 (two of four shown) which may be screws.

It is understood that hole 58 may communicate with the first output port 9 via an interconnecting conduit (not shown) where it is desired to space the thermostatically controlled diverter valve 7 above and away from the perforated partition plate 60.

Preferably the input fitment 23 and the output fitment 24 are compatible with conventional plumbing conduits to facilitate permanent connection to a conventional fluid source supply system. In at least one other embodiment the input fitment 23 and the output fitment 24 are compatible with conventional plumbing hose connections to facilitate installation, including retrofitting.

In embodiments, wherein the thermostatically controlled diverter valve 7 is internal, it is preferred that a filter (not shown) is provided to prevent foreign matter/debris from entering the thermostatically controlled diverter valve 7. The filter may be a perforated membrane (not shown) disposed at the input fitment 23 in such a way as to be easily accessible for cleaning.

With reference to Figures 5, 7, 8, 9A, 9B, 10 and 11, and according to at least one embodiment of the present invention the thermostatically controlled diverter valve 7 is external to the container 1. An externally disposed thermostatically controlled diverter valve may be of the type actuated by a thermally sensitive part 29 as aforementioned and described. Alternatively, the thermostatically controlled diverter valve may be a mechanical change over valve actuated by an electrical solenoid or motor (not shown), the solenoid or motorised valve being in electrical communication with a thermal sensing fitment (not shown). Such a thermal sensing fitment may be a conventional conduit clip mounted sensor (not shown) which may be disposed in contact with source conduit 42, adjacent to the input port 8 such that when fluid arriving at the input port 8 from a fluid source 40 via the source conduit 42, is below a predetermined temperature or above a predetermined temperature, the sleeve 27 directs fluid out of the first output port 9 or out of the second output port 10 respectively. There is fluid communication between the first output port 9 and input fitment 23, provided by interconnecting conduit 43A, and fluid communication between the output fitment 24, the delivery conduit 44, and the second output port 10 is provided by interconnecting conduit 43C.

Figs. 9A and 9B show simplified diagrams of the fluid flow for the external thermostatically controlled diverter valve 7 from fluid source 40 to user point 45 for when the end gap 82 is closed and for when the porch gap 83 is closed respectively.

In at least one embodiment of the present invention, wherein the thermostatically controlled diverter valve 7 is external, there is provided a perforated partition plate 60 to control turbulence caused by fluid entering the container 1. The perforated partition plate 60 has a hole 58, which engages with interconnecting conduit 43B, which is in fluid communication with input fitment 23, such that fluid is directed to the cavity 59 below the perforated partition plate 60 via conduit open end 69 so that fluid rises through the openings 57 from the cavity 59. The perforated partition plate 60 being preferably spaced from the floor 25 of the container 1 by an amount such that were the cylindrical conduit, defining the open end 69, to occupy that space, the surface area of that conduit that would have been in that space would be approximately equal to but not less than the cross-sectional area of the bore of the interconnecting conduits 43, so that fluid can flow freely via the plurality of openings 57 and into the lower internal zone 35 of the container 1. Fluid is forced from the upper internal zone 34 into the conduit open end 72 of the interconnecting conduit 43C and on via the delivery conduit 44 to the user point 45. The perforated partition plate 60 may be supported as aforementioned and described. The diameter of hole 58 may be specific to a particular embodiment.

With reference to Fig. 12, in another embodiment of the present invention there is provided a partition cap in the form of a perforated cylinder 94 to control turbulence caused by fluid entering the container 1.

The perforations are a plurality of openings, which may be vertical elongated slots 92 (13 shown), separated by spaces 93, distributed around the entire circumference of the perforated cylinder 94, where preferably the width of space 93 is equal to width of slot 92. The perforated cylinder 94 is further characterised by a wall 95 of internal diameter not less than, and preferably marginally greater than, the internal diameter of the interconnecting conduit 96, the perforated cylinder 94 being closed at the lower end 100, where such closure may be provided by the floor 25 of the container 1. The slots 92 are preferably substantially narrow relative to the diameter of the interconnecting conduit 96, and preferably the vertical length of the slots 92 is approximately equal to the internal diameter of interconnecting conduit 96. The total cylindrical area of the slots 92 is preferably substantially greater than the internal cross sectional area of the interconnecting conduit 96. Preferably the lower ends of such slots are disposed close to the container floor 25. The perforated cylinder is in fluid communication with the output port 9 of an internal thermostatically controlled diverter valve 7, as aforementioned and described with other Figures, or the output port 9 of an external thermostatically controlled diverter valve 7, as aforementioned and described with other Figures, such that fluid enters the internal cavity of the perforated cylinder via interconnecting conduit 96 from above (shown), and such that fluid under pressure from a fluid source will be forced out of the cavity via the slots 92 into the lower internal zone 35 of the container 1 in the shape of a horizontal radial pattern.

With reference to Fig 13 a perforated cylinder 102, substantially as aforementioned and described for perforated cylinder 94, may be in communication with the first output port 9 of an external thermostatically controlled diverter valve, as aforementioned and described with other Figures, via interconnecting conduit 104 such that the input port 103 may be disposed in the floor 25 of the container 1 so that fluid enters the internal cavity 101 from below, and such that fluid under pressure from a fluid source will be forced out of the cavity via the slots 92 into the lower internal zone 35 of the container 1.

The perforated cylinder 102 may be integrally fabricated with the input port 103 and flange 106 and is closed at the upper end where such closure may be provided by an end stop 105. It being understood that where components are fabricated in metal, the flange 106 may be secured to the floor 25 of the container by conventional means such as brazing or soldering as required, or, and particularly where components are fabricated in plastic, the cylinder may be inserted and secured by a screw-threaded boss (not shown), integrally fabricated in the container floor 25, communicating with corresponding screw threads (not shown) in the lower end of the perforated cylinder 102.

With reference to Figs. 2 and 12, it is clear from the foregoing that the perforated cylinder 94 may be incorporated instead of the perforated partition plate 60 and that the perforated cylinder 94 communicates with the first valve output port of the internal thermostatically controlled diverter valve 7 via the interconnecting conduit 96, and that with reference to Figs. 7 and 12, the perforated cylinder 94 may be incorporated instead of the perforated partition plate 60 and that the perforated cylinder 94 communicates with interconnecting conduit 43B via interconnecting conduit 96.

Furthermore, with reference to Figs. 7 and 13, it is clear from the foregoing that the perforated cylinder 102 may be incorporated instead of the perforated partition plate 60 and that the perforated cylinder 102 communicates with the first valve output port 9 of the external thermostatically controlled diverter valve 7 via interconnecting conduit 104 instead of interconnecting conduits 43A and 43B and input fitment 23.

In embodiments where the thermostatically controlled diverter valve 7 is external, it is preferred that a filter (not shown) is provided, to prevent foreign matter/debris from entering the thermostatically controlled diverter valve 7. This filter may be a perforated membrane (not shown), disposed at the input port 8 in such a way as to be easily accessible for cleaning.

Preferably the electric heating device 11 is disposed in the lower zone 35 of the container 1 and the housing 13 (not shown in Figure 7) for the fluid thermal sensor 12 is disposed in the lower zone 35 on the opposite side from the electric heating device 11.

An electrical override cut-out switch 74 may be provided, which is thermally engaged with the roof 26 of the container 1 such that power is cut to the electric heating device 11, if, under fault conditions, the temperature of the fluid in container 1 rises above a predetermined safety limit. The override cut-out switch 74 may be of the conventional surface-mounted (not shown) or stud mounted (shown) bi-metal disk type or any other convenient conventional device and preferably of the type that requires the power to be switched off before the override cut-out switch 74 can be re-set. The thermal operating point of the electrical override cut-out switch 74 should be below the fluid's boiling point and substantially above the normal maximum operating temperature of the fluid in container 1.

It is understood that where the container I is fabricated in plastics a surface mounted cut-out switch 74 may not be suitable because of the likely lower thermal conductivity of plastics material as compared with metal, in which circumstances an insertion type device (not shown) may be provided.

Sealing means, such as washers or the like (not shown), may need to be provided to seal the openings in the container 1 through which the various components pass, so that container I and all related component plumbing parts are fabricated and sealed to withstand fluid pressures such as are required for installation in un-vented or vented systems, including domestic water supply installations, depending upon requirements.

In preferred embodiments destined for domestic applications the thermostatically controlled diverter valve 7 and all interconnecting conduit may be compatible with either 22mm or 15mm delivery and supply conduits depending upon requirements.

In preferred embodiments the container 1 is thermally insulated by means of an external jacket 75, which may be fabricated in expanded polystyrene or any other conventional thermal insulation material. This may be contained within an outer retainer (not shown) which may be fabricated in metal or plastics. The container may be thermally insulated by the provision of a metal double skinned container (not shown) enclosing a vacuum instead of the shown single skinned container 1.

In the horizontal plane the container 1 may be generally cylindrical (shown), wherein the height to diameter ratio is preferably at least one, or generally rectangular (not shown) wherein the height to width ratio is preferably at least one. Rectangular embodiments are preferably square.

In preferred embodiments the container 1 and perforated partition plate are fabricated in metal, such as aluminium, copper or stainless steel. A suitable plastics material may be used.

Figs. 10 and 11, show the electrical relationship between various parts of the present invention. A mains electricity supply 55 and distribution circuit 21, which may be a l3amp ring main, supplies mains AC to a low output voltage transformer and DC rectification unit 20 to provide the correct DC power supply for the thermostatic electronic control circuit 73. The thermostatic control unit 52 comprises the electronic control circuit 73 and the relay switch 50 which are in electrical communication with the thermal sensor 12. The electrical power supply for the heater 11, connected in series with the override cut-out switch 74 and relay switch 50 is derived from the distribution circuit 21.

Interconnectivity is provided at 17, 19, 22 for the heater 11, override cut-out switch 74 and relay switch 50 respectively. Interconnectivity is provided at 18 for the thermal sensor 12, and interconnectivity is provided at 54 for the DC power supply for the electronic circuit 73. A potentiometer type control facility 53 provides the means for the user to adjust for the predetermined temperature of the fluid in the container 1. The relay switch 50 is shown with the contacts in the "normally closed" position, which would apply when the fluid in the container 1 is lower than the predetermined temperature or the power to the electronic circuit is off.

It is understood that, where the present invention is used in an un-vented installation, an external conventional expansion vessel may be desired. It is also understood that an external or internal pressure relief valve may be required.

Although specific embodiments of the present invention have been described and illustrated, various modifications may be made within the scope of the invention, such as for example the openings 57 could be a plurality of small round holes (not shown), the diameter of such holes being substantially less than the diameter of the interconnecting conduits 41, 43 the total cross- sectional area of the round holes being substantially greater than the cross-sectional area of the bore of the interconnecting conduits 41, 43. Also, for example, the electrical heating device 11 may be a conventional immersion heater (not shown) which may be mounted in the roof 26, having length such that the actual heating part is disposed, preferably, to one side in the lower internal zone 35 of container 1. Also, for example, an alternative configuration (not shown) of the electronic circuit could be used such that the relay switch is "normally open" when the power to the electronic circuit is off.

While the invention has been described with a certain degree of particularity it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the

spirit and scope of this disclosure.

Claims

CLAIMS1. A fluid heater comprising: -a container; -a fluid input and a fluid output; -a thermostatically controlled diverter valve with an input port, a first output port and a second output port, a thermally sensitive part in thermal communication with fluid at said input port such that if the temperature of fluid arriving at said input port from a source conduit is below a predetermined temperature it is directed out of said first output port into a lower portion of said container, and if the temperature of fluid entering the said input port is above a predetermined temperature, it is directed to the second output port and then to downstream use; -fluid communication means between the container and the fluid output such that when fluid is introduced into the container from the first output port fluid is forced from the container through the fluid output for downstream use; -a heater to heat the fluid in the container; and -switch means for controlling the heater in response to the temperature of fluid in the container such that the heater is switched on when the temperature of fluid in the container falls below a predetermined temperature, and is switched off when the temperature of fluid in said container rises above a predetermined temperature.
2. A fluid heater as claimed in claim 1, wherein the thermostatically controlled diverter valve is located substantially within the container.
3. A fluid heater as claimed in claim 1, wherein the thermostatically controlled diverter valve is located substantially outside the container.
4. A fluid heater as claimed in any of the preceding claims, wherein the thermostatically controlled diverter valve is a mechanically activated valve wherein the thermally sensitive part is a component which alters in shape or size in response to changes in temperature.
5. A fluid heater as claimed in any of claims I to 3, wherein the thermostatically controlled diverter valve is activated electrically by a solenoid or motor.
6. A fluid heater as claimed in any of the preceding claims wherein the switch means comprises a thermal sensor configured to sense the temperature of fluid within the container, and a control circuit to control switching of the heater.
7. A fluid heater as claimed in claim 6, wherein the heater is disposed in a lower internal portion of said container.
8. A fluid heater as claimed in claim 7, wherein the thermal sensor is also disposed in said lower internal portion, remote from said heater.
9. A fluid heater as claimed in any of the preceding claims, further comprising means for controlling turbulence caused by fluid entering the container.
10. A fluid heater as claimed in claim 9, wherein the means comprises a partition plate having a plurality of openings through which fluid passes.
11. A fluid heater as claimed in claim 9, wherein the means comprises a partition cap having a plurality of slots through which fluid from the first output port is directed upon entry into the container.
12. A fluid heater as claimed in any of the preceding claims, wherein the predetermined operating temperature setting of the thermostatically controlled diverter valve may be adjusted.
13. A fluid heater as claimed in claim 12, wherein the thermostatically controlled diverter valve is located within the container and a spindle extends from the thermostatically controlled diverter valve passing through the wall of said container via a fluid-tight gland to an external adjustment facility.
14. A fluid heater as claimed in any of the preceding claims, wherein the container is thermally insulated.
15. A fluid heater as claimed in claim I and substantially as hereinbefore described with reference to the accompanying drawings.
16. A kit for installation of a fluid heater, said kit comprising: -a fluid heater as claimed in any of the preceding claims; -means for connecting a hot water supply pipe to the fluid input and to the fluid output so that the fluid heater can be installed directly into the hot water supply pipe; and -means for connecting the fluid heater to an electrical supply for the supply of electrical energy to the heater.
17. A kit as claimed in claim 16, wherein the means for connecting a hot water supply are screw-on flexible hoses.