Field of the invention

[0001] The present invention relates to a water heater, and in particular, to a water heater of the type which has a storage tank and which is typically used for storing hot water for domestic or commercial use.

[0002] The present invention in particular, relates to the provision of a plurality of temperature sensors on a sensor strip, the strip being adapted to be inserted within a sensor housing, the housing being provided on an exterior surface of the storage tank of the water heater. In use, the sensors are adapted to sense the temperature of the water at various positions/heights within the water storage tank, so as to thereby regulate the temperature of the water stored in the storage tank.

Background of the invention

[0003] Any reference herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates, at the priority date of this application.

[0004] Water heaters of the type which have a storage tank, and which are typically used in domestic or commercial applications, typically include at least one temperature sensor and at least one water heating element. The temperature of the water stored within the tank is typically monitored using the temperature sensor(s), and, the operation of the heating element(s) is thereby controlled according to the sensed temperature.

[0005] Due to the different densities of hot and cold water, temperature stratification typically occurs in such water heater storage tanks, whereby the stored water is not evenly warmed throughout the tank. Whilst the water temperature at the top of the tank may be quite hot, at the bottom of the tank the water temperature can be quite cold. In a domestic hot water system, the water on the top of the tank may typically be 65°C to 75°C, whilst at the bottom of the tank it may be 10°C to 70°C.

[0006] In recent times, in the quest for greater efficiency and convenience, a plurality of temperature sensors have been additionally incorporated at various locations within hot water heater tanks, such that the temperature of the water stored within the tank may be better monitored, and so that the operation of the heating element(s) within the hot water heater may therefore be better controlled.

[0007] These temperatures sensors may, for example, be used to detect the location of the transition zone of the hot and cold water within the storage tank, and, in association with a processor thereby control the operation of the heating element(s) to thereby heat more or less of the stored water to be heated depending upon the demand requirements of the user(s). In this way, only the amount of water which may be required by the user can be heated, thus saving energy for unnecessarily heating unrequired water.

Summary of the invention

[0008] The present invention seeks to provide an improved temperature sensing arrangement for readily monitoring and/or controlling the temperature of water housed in a water heater storage tank.

[0009] The present invention also seeks to provide a sensor strip assembly, incorporating a plurality of temperature sensors thereon, which can be readily mounted to a water heater storage tank.

[0010] The present invention also seeks to provide a water heater configured to incorporate a sensor strip assembly provided with a plurality of temperature sensors.

[0011] The present invention also seeks to provide a temperature control system for a water heater which utilises sensed water heater temperature data received from a plurality of temperature sensors provided on a sensor strip assembly.

[0012] The present invention also seeks to provide a method of controlling the temperature of water in a water heater which incorporates a sensor strip to sense water heater temperature, and, thereby control the operation of at least one water heating element.

[0013] The present invention also seeks to provide a method of installing, removing and/or replacing a sensor strip assembly within a water heater.

[0014] In one broad form, the present invention relates to a water heater, including: a storage tank; a substantially elongated sensor housing provided on an exterior surface of said storage tank; and, a sensor strip, including a plurality of temperature sensors thereon, adapted to be inserted within said sensor housing. [0015] Preferably, said sensor strip includes: a substantially elongate substrate on which said plurality of sensors are provided in spaced apart relationship.

[0016] Preferably, said substrate includes any one or combination of: a composite material having mechanical strength and electrical insulative properties, including in humid conditions; a thermoset plastic laminate material, including having high strength to weight ratios, low water absorption properties, and/or flame retardant properties; a glass epoxy material, such as FR-4 material; a printed circuit overlay, formed of a conductive material, such as a plating of copper; and, a polyamide material.

[0017] Preferably, said sensor housing includes any one or combination of: a material including a metal or alloy, such as aluminium or an aluminium alloy; a shaped profile adapted to slidably receive said elongate sensor strip therein; and, an elongate shaped profile formed by using an extrusion or other process.

[0018] Preferably, the water heater further includes: an insulation layer, substantially surrounding said water tank; and, a cover/jacket, substantially surrounding said insulation layer.

[0019] Preferably, a first side of said sensor housing abuts said exterior surface of said storage tank; and, said insulation layer substantially surrounds the remainder of said sensor housing.

[0020] Preferably, said sensor housing is secured to said exterior surface by any one or combination of: using an adhesive; by using a tape, such as a masking tape; by welding or soldering; and, by using an interlocking mechanism.

[0021] Preferably, the water heater further includes: a processor, configured to control the operation of at least one water heating element located within said water tank.

[0022] Preferably, said processor controls the operation of said at least one water heating element according to a predetermined algorithm and utilising sensed water heater data received from each of said plurality of temperature sensors.

[0023] In a further broad form, the present invention relates to a sensor strip including a plurality of temperature sensors thereon, the sensor strip configured to be inserted within a sensor housing provided on an exterior surface of a water heater storage tank.

[0024] Preferably, the sensor strip further includes a substantially elongated substrate on which said plurality of sensors are provided in spaced apart relationship. [0025] Preferably, said substrate includes any one or combination of: a composite material having mechanical strength and electrical insulative properties, including in humid conditions; a thermoset plastic laminate material, including having high strength to weight ratios, low water absorption properties, and/or flame retardant properties; a glass epoxy material, such as FR-4 material; a PCBA material, including a polyester PCBA material; a printed circuit overlay, formed of a conductive material, such as a plating of copper; and a polyamide material.

[0026] In a further broad form, the present invention relates to a sensor housing, adapted to be installed on and exterior surface of a water heater storage tank, and configured to house a sensor strip, which includes a plurality of temperature sensors thereon, inserted therein.

[0027] Preferably, the sensor housing includes any one or combination of: a material including a metal or alloy, such as aluminium or an aluminium alloy; a shaped profile adapted to slidably receive said elongate sensor strip therein; and, an elongate shaped profile formed by using an extrusion or other process.

[0028] In a further broad form, the present invention relates to a method of installing/removing/replacing a sensor strip in a water heater, including the steps of: slidably inserting/removing said sensor strip within a sensor housing which is provided on an exterior surface of a storage tank of said water heater.

[0029] In a further broad form, the present invention relates to a method of controlling the temperature of a water heater storage tank, including the steps of: installing a sensor strip into a sensor housing provided on an exterior surface of said water tank, wherein the sensor strip includes a plurality of temperature sensors thereon adapted to thereby sense water heater temperature at a plurality of spaced apart locations in said water tank; electrically connecting each temperature sensor to a processor adapted to thereby control the operation of at least one water tank heating element according to a pre-determined algorithm which utilises the sensed water heater temperatures at the spaced apart locations in the water tank.

[0030] In a further broad form, the present invention relates to a water heater temperature control system including: a plurality of temperature sensors arranged in spaced apart relationship on a sensor strip installed in an elongate sensor housing on an exterior surface of a water heater storage tank; and, a processor, configured to control the operation of at least one water heating element according to a predetermined algorithm, utilising sensed water heater temperature data received from each of said plurality of temperature sensors.

Brief description of the drawings

[0031] The present invention will become more fully understood from the detailed description of preferred but nonlimiting embodiments thereof, described in connection with the accompanying drawings, wherein:

[0032] Figure 1 illustrates a partially cutaway isometric view of a prior art water heater;

[0033] Figure 2 illustrates a partially cutaway isometric view of a water heater incorporating a sensor strip assembly in accordance with the present invention;

[0034] Figure 3 illustrates cross-sectional views of the water heater shown in Figure 2;

[0035] Figure 4 illustrates a side view of an example embodiment of a storage tank of a water heater, without the cover/jacket thereon;

[0036] Figure 5 illustrates details of the sensor strip of the present invention;

[0037] Figure 6 illustrates various views of a water heater with the cover/jacket thereon;

[0038] Figure 7 illustrates an exploded view of an example embodiment of a water heater in accordance with the present invention;

[0039] Figure 8 illustrates various views of an example embodiment of a sensor housing of the present invention;

[0040] Figure 9 illustrates further views and details of the sensor housing of the present invention;

[0041] Figure 10 illustrates yet further details of the sensor housing of the present invention; and,

[0042] Figure 11 illustrates how a sensor strip may be installed, removed, or replaced, to within the sensor housing of an assembled water heater. Detailed description of preferred embodiments

[0043] Throughout the drawings, like numerals will be used to identify like features, except where expressly otherwise indicated.

[0044] Figure 1 illustrates a partially cutaway isometric view of a prior art water heater 1 of the type which has a storage tank 2 and which is typically used for storing and heating water for domestic or commercial use. The storage tank 2 of the water heater 1 is typically encapsulated by an insulative layer 3. The water heater 1 , shown in Figure 1 , incorporates a pair of heating elements, that is, an upper heating element 4 and a lower heating element 5. A temperature sensor located within the tank 2 sensors the temperature of the water within the tank 2, and operates the heating elements 4 and 5 accordingly to heat the water. Cold water supplied through inlet 6 is accordingly heated by a heating elements 5 and 6, and hot water is egressed via water outlet 7.

[0045] Figures 2 and 3 illustrate the water heater 1 of the present invention. Figure 2 shows a partially cutaway isometric view of a water heater 1 , of similar configuration to that of Figure 1 , but showing the incorporation of a sensor strip arrangement 10 provided within a sensor housing 11. Figure 3 illustrates, in Figures 3a and 3b, cross sectional views through a horizontal and a vertical plane, respectively.

[0046] As can be seen in Figures 2 and 3, and as will be described more fully hereinafter, the water heater 1 of the present invention incorporates a substantially elongate sensor housing 11 provided on the exterior surface 12 of the storage tank 2. As can also be seen in Figures 2 and 3, a sensor strip 10, which includes a plurality of temperature sensors 13, is provided within the sensor housing 11.

[0047] Figure 4 shows the internal water tank 2 of the water heater 1 , with the sensor strip 10 attached to its exterior surface 12. The sensor housing 11 is not shown in this drawing, for illustrative purposes.

[0048] Figure 5 illustrates, in schematic form, details of an example embodiment of the sensor strip 10. Figure 5(a) shows a top view of the sensor strip 10, whilst Figure 5(b) and 5(c) show end and side views of the sensor strip 10, respectively.

[0049] The sensor strip 10 of the present invention is preferably formed of substantially elongate form, and, incorporates a substrate 14, and, a plurality of conductive tracks 28. A plurality of sensors 13 are provided in spaced apart relationship, electrically connected between each pair of conductive tracks. Alternative configurations will become apparent to persons skilled in the art, which may reduce the number of wiring connections. For example, one alternative example design uses a common track connecting one side of each sensor, and, a separate track for each sensor. Another example design includes a small microcontroller on the sensor board to measure the output of each temperature sensor which communicates with the main controller via a serial interface. A further example design uses sensor chips each having a built-in serial interface.

[0050] The substrate 14, in an example embodiment, may be formed of a composite material which has high mechanical strength and good electrical insulative properties. Preferably, the material of which the substrate 14 is formed is stable in humid conditions, as may be typically experienced in the environment of a water heater 1. By way of example, the substrate may be a thermoset plastic laminate material, which has high strength to weight ratios, low water absorption properties, and/or flame retardant properties. A glass epoxy material, such as FR- 4 material is an example of a suitable material. In an alternative example embodiment, the composite material may be polyamide material.

[0051] The substrate 14 supports conductive tracks 28, which may be embodied as a printed circuit overlay. The conductive tracks 28 may, for example, be formed as a plating of copper.

[0052] The sensor strip 10 is, in an example embodiment, a rigid flexible material, the purpose for which will be described hereinafter. The temperature sensors 13 which may be provided in spaced apart relationship on the sensor strip 10 may be of any known type, such as, but not limited to, thermistor temperature sensors 13.

[0053] It should be noted that, in the exemplified configuration, there needs to be no direct contact between the temperature sensors 13, and either the sensor housing 11 or the exterior surface 12 of the tank 2, as the temperature measured by the sensors 13 will substantially match the temperature of the exterior surface of the water tank, and the water within the water tank adjacent thereto, due to convection, conduction, and radiation effects. Whilst it is acknowledged that the response time of the sensors 13 may be slightly lower than if there was direct contact with the sensor housing 11 and/or the exterior surface 12 of the tank 2, the temperature readings obtained by this configuration are considered to be perfectly acceptable and adequate for the application. [0054] Figure 6 shows isometric, side elevations, and a plan view of the water heater 1 , fully assembled, whilst Figure 7 illustrates an exploded view of the water heater 1 to illustrate the various component parts thereof. As illustrated in Figure 7, the water tank 2 is adapted to receive heating elements/blades 4 and 5 in the lower and upper regions of the water tank 2, the various components for installation of the blades 4 and 5 also being illustrated. Whilst the example embodiment illustrated in the drawings shows a pair of blades in the water heater, it will be appreciated and well understood by persons skilled in the art that any number of heating elements/blades may be incorporated in such a water heater, including one, two, three, or a plurality of heating elements. Figure 7 also illustrates the water inlet components 6 and the water outlet components 7. The sensor strip 10 and a sensor strip housing 11 are also illustrated, and, as hereinbefore described, are ultimately installed on the exterior surface 12 of the water tank 2. The outer cover or jackets 19 of the water heater 1 together with top and bottom end plates 21 , respectively are also illustrated.

[0055] Figure 8 illustrates an example embodiment of a sensor housing 11. The sensor housing 11 as illustrated in Figure 8 is of substantially elongate form, and is shown having a first side 15 which is very slightly rounded, appearing substantially flat, so as to substantially abut the exterior radius surface 12 of the storage tank 2, and, and otherwise rounded profile surface 16. A void 17 is therefore defined intermediate the flat surface 15 and the rounded surface 16, into which the sensor strip 10 may be inserted. It will be appreciated that the shape of the sensor housing 11 may take a variety of forms, and may be of any desired shape, such as rectangular, triangular, etc.

[0056] The sensor housing 11 is preferably formed of a material including a metal or metal alloy, such as aluminium or an aluminium alloy, are examples of materials which may be appropriate.

[0057] The void area 17 within the sensor housing 11 , preferably has a shaped profile so that it is adapted to slidably receive the elongate sensor strip 10 therein. For example, a pair of protrusions 18 may optionally be provided to assist the guidance of the sensor strip 10 into its desired position within the sensor housing 11 whilst also providing structural support for the housing 11 , and, maintaining the sensors substantially in contact with the exterior surface 12 of the water tank 2.

[0058] The sensor housing 11 of such shape may be readily formed by using an extrusion process. The sensor housing 11 may then be installed on the exterior surface 12 of the tank 2 of the water heater 1 , during the manufacturing process of the water heater 1. The housing 11 may be attached to the exterior surface 12 of the tank 2 by using masking tape or the like, by using an adhesive, by welding or soldering the housing to the tank, and/or, by using an interlocking mechanism, etc.

[0059] Once the sensor housing is installed on the exterior surface 12 of the water tank 2, the insulation layer 3 may then be installed to substantially surround the exterior surface 12 of the water tank 2. Thereafter, the water tank cover or jacket 19 is then positioned around the insulation layer 3. Alternatively, the insulation layer 3 is inserted between the water tank 2 and the water tank cover or jacket 19.

[0060] As such, the sensor housing 11 is substantially surrounded with one side, abutting to the exterior surface 12 of the storage tank 2, and with the remainder of the sensor 11 housing being encapsulated by the insulation layer 3 of the water heater 1 .

[0061] As such, in use, the plurality of temperature sensors 13 are configured to sense the temperature of the water tank 2, which substantially approximates the temperature of the water within the water tank 2, which is immediately on the other side of the respective portion of the exterior surface 12 of the storage tank 2.

[0062] Figure 9 illustrates, various views of the sensor housing 11 , illustrating the elongate form of the sensor housing, showing an upper end cap 22 and a lower end cap 23, which may be used to terminate the ends of the housing. The lower end cap 23 may additionally incorporate an attachment mechanism to retain the sensor strip 10 within the housing 11.

[0063] Figure 10 illustrates various views of the sensor housing 11 , illustrating how, with the sensor strip 10 installed therein, the end of the sensor strip 10 may be electrically connected to the processor/control circuitry of the water heater 1. In particular, Figure 10 illustrates the attachment of a wire ribbon cable 24 to the sensor strip 10 when installed in the sensor housing 11 via an appropriate connector 25.

[0064] In use, data obtained from the temperature sensors 13 is accordingly communicated via conductive material overlaid on the substrate of the sensor strip 10 to a processor. The processor is configured to control the operation of the water heating element(s) 5 and 6 depending upon the sensed water heater data, and, according to a predetermined algorithm. These processing techniques, processing apparatus, algorithms, etc are known and well understood to person skilled in the art, and therefore are not further described herein. The present invention does however encompass the incorporation of these known techniques, apparatus and algorithms within a water heater, in so far as they interrelate to utilising these with the temperature sensors 13 configured on a sensor strip 10 incorporated in the sensor housing 11 .

[0065] Likewise, the present invention also encompasses a method of controlling the temperature of the water heater storage tank whereby a sensor strip is installed into a sensor housing provided on an exterior surface of a water tank, and, wherein the sensor strip includes a plurality of temperature sensors adapted to thereby since water heater temperature at a plurality of spaced apart locations in a water tank, and, controlling the operation of at least one water tank heating element utilising the sensed water heater temperatures taken from the temperature sensors 13, and, processing these sensed temperatures in an algorithm to thereby control the temperature of the water within the tank 2.

[0066] The sensor strip 10 of the present invention may either be installed within the housing 11 at the time of manufacture of a water tank 1 , or, may be retrofitted at a later stage. For example, in some commercial applications it may be desired to manufacture a standardised water tank which does not necessarily incorporate a plurality of temperature sensors, but, allows the possibility for the standardised water tank to be upgraded by a user at a later time. Therefore, the present invention encompasses a configuration whereby the sensor strip 10 may, be later installed or retrofitted within a sensor housing 11 which has already been installed on the exterior surface 12 of the water tank 2 at the time of manufacture of the water heater 1 .

[0067] As such, an opening to the sensor housing 11 may be provided, as illustrated in Figure 3b. In such configurations, the sensor strip is therefore formed of a somewhat rigid but also flexible material so that it can be bent during the insertion process and so that it then resiliently returns to a substantially straight configuration once installed in the housing 11.

[0068] Figure 11 illustrates how a insertion ramp 27 may be provided adjacent the opening 26 of the housing 11 , to facilitate insertion of the sensor strip 10. It will be appreciated that the insertion ramp 27 may be a permanently installed component, or a releasably removable component which is releasably attachable adjacent the opening 26 of the sensor housing 11 at the time the sensor strip 10 is to be installed. Figure 11 (a) shows an opening 26 without a ramp 27 attached, whilst figure 11 (b) shows an opening 26 with the ramp 27 attached thereto. [0069] It will be appreciated that this configuration of sensor strip housing 11 incorporating the opening 26 also facilitates the ability to, if desired, replace a sensor strip 10 if it becomes broken or damaged, and/or, upgrade a sensor strip 10 to incorporate additional temperature sensors 13 thereon if a more sophisticated processor is desired to be used with the particular water heater 1 .

[0070] Whilst particular example embodiments of a water heater incorporating a sensor strip within a sensor housing, and attached to an exterior of the water tank have been hereinbefore described and shown in the accompanying drawings, it will be appreciated that numerous variations and modifications to these particular configurations and components can be made. All such variations and modifications which are apparent to person skilled in the art from a reading of this specification should be considered to be encompassed within the spirit and scope of the specification as hereinbefore described and as hereinafter claimed.