AU2016204981A1

AU2016204981A1 - A water heating system

Info

Publication number: AU2016204981A1
Application number: AU2016204981A
Authority: AU
Inventors: Patrick Pussel
Original assignee: DUX Manufacturing Ltd
Current assignee: DUX Manufacturing Ltd
Priority date: 2010-05-26
Filing date: 2016-07-15
Publication date: 2016-08-04
Also published as: NZ601605A; WO2011146962A1; AU2011257945B2; AU2011257945A1

Abstract

A WATER HEATING SYSTEM Abstract 5 A water heating system (10) including a water storage tank (14), a first mains water tank inlet (16), a first water tank outlet (18), an instantaneous-type water heater (12), a second water tank outlet (24), a second water tank inlet (28), a tank water temperature sensor (34) and a controller(32). The water storage tank (14) has a top and a bottom. The first mains water tank inlet (16) is at or near the bottom of the tank (14). The first water tank outlet 10 (18) is at or near the top of the tank (14). The instantaneous-type water heater (12) has an inlet (20) and an outlet (22). The second water tank outlet (24) is at or near the bottom of the tank (14) and is in fluid communication with the inlet (20) of the instantaneous-type water heater (12). The second water tank inlet (28) is in fluid communication with the outlet (22) of the instantaneous-type water heater (12). The controller (32) is adapted to is energise the instantaneous-type water heater (12) in response to the tank water temperature sensor (34) indicating to the controller (31) that the temperature of the water in the tank (14) is substantially equal to or below a first predetermined value.

Description

A WATER HEATING SYSTEM

Field of the Invention

The present invention relates to a water heating system.

The present invention has been primarily developed for use with gas instantaneous type water heaters and will be described hereinafter with reference to that application. However, the invention is not limited in this particular field of use and can also be used with electrical instantaneous-type heaters. In the United States of America, instantaneous-type water heaters are known as tank-less heaters.

Background of the Invention

Known instantaneous type heaters have an inlet, connected to a mains water supply, and an outlet connected to, for example, a tap. The flow of water through the heater automatically energises the gas burners or electrical elements therein. This known arrangement has two disadvantages.

The first disadvantage relates to water wastage. When a user activates a hot water tap, the user must wait for the mains supplied water to be heated, and for all the unheated water in the pipes between the heater outlet and the tap to be purged, before receiving the heated water at the tap. The Australian Federal Government departments concerned with water conservation estimate that usage of this type in an average household occurs about 19 times a day and wastes up to 90 litres of water a day.

The second disadvantage relates to two types of gas wastage. The first type of gas wastage occurs because, as mentioned above, known instantaneous type heaters ignite their burners upon sensing flow of water through the heater, caused by opening a hot water tap. In the case of a shower, the heater takes some time to come up to temperature and the cool-to-warm water delivered in the intervening heating period is often dumped to waste by the householder. The second type of gas wastage occurs because many users only turn on the hot tap when washing their hands, wash in the initial cold-to-lukewarm water, and then simply turn off the tap. In that situation, gas is used to solely go through a start up phase and heated water is left in the pipes, which then cools and is thus wasted.

It is an object of the present invention to reduce water and gas wastage in water heating systems utilizing an instantaneous-type water heater and to provide alternatives and improvements to the systems described in the Applicant’s International PCT Patent Application No. PCT/AU2009/001432.

Summary of the Invention

Accordingly, the present invention provides a water heating system including: a water storage tank having a top and a bottom; a first mains water tank inlet at or near the bottom of the tank; a first water tank outlet at or near the top of the tank; an instantaneous-type water heater having an inlet and an outlet; a second water tank outlet at or near the bottom of the tank a second water tank inlet in fluid communication with the outlet of the instantaneous-type water heater; a first pump having an inlet and an outlet, the first pump inlet being in fluid communication with the second water outlet and the first pump outlet being in fluid communication with the inlet of the instantaneous-type water heater; a third water tank inlet at or near the bottom of the tank; a heat exchanger having a water inlet, a water outlet, an air inlet and an air outlet, the heat exchanger water outlet being in fluid communication with the third water tank inlet; a second pump having an inlet and an outlet, the second pump inlet being in fluid communication with the first water tank outlet and the second pump outlet being in fluid communication with the heat exchanger water inlet; a user control input device; and a controller, wherein, in response to a user input to the user control input device, the controller energises the second pump to drive water through the heat exchanger.

The heat exchanger preferably includes a fan adapted to drive air through the heat exchanger, for heat exchange with the water being driven therethrough, and the controller energises the fan and the second pump together.

The controller is preferably further adapted to vary the speed of the energised second pump and of the fan in order to control the temperature and flow rate of the air leaving the heat exchanger.

In one form, the water heating system includes a tank water temperature sensor and the controller is further adapted to energise the instantaneous-type water heater in response to the tank water temperature sensor indicating to the controller that the temperature of the water in the tank is substantially equal to or below a first predetermined value.

The first predetermined value is preferably about 50 degrees C.

The water heating system preferably includes a temperature sensor, most preferably at or near the bottom of the tank.

The instantaneous-type water heater preferably has a fixed power output.

In another form, the system also includes a first water temperature sensor adapted to provide a first signal indicative of the temperature of the water upstream of the first pump; and a second water temperature sensor adapted to provide a second signal indicative of the temperature of the water downstream of the water heater, wherein the controller is further adapted to energise the first pump and the water heater in response to the first temperature sensor indicating to the controller that the temperature of the water upstream of the first pump is substantially equal to or below a first predetermined value, and wherein the controller is further adapted to vary the speed of the energised first pump such that the second temperature sensor indicates to the controller that the water at or downstream of the outlet of the instantaneous-type water heater is a substantially constant second predetermined value.

The first predetermined value is preferably about 50 degrees C. The second predetermined value is preferably about 70 degrees C.

The instantaneous-type water heater preferably has a fixed power output.

The controller preferably monitors the first pump to thereby determine the volume of pumped water. The first pump preferably includes a motor. In one form, the motor is controlled by pulsing, whereby the revolutions per minute can be monitored and thus the pumped volume calculated. In this form, the controller has an embedded algorithm such that the pulsing is altered relative to the incoming water temperature and the outgoing water temperature. In another form, the revolutions per minute of the motor can be monitored with a tachometer to calculate pumped volume.

In yet another form, the water heating system further includes: first, second and third temperature sensors at or near the top, middle and bottom of the tank respectively; and a fourth water temperature sensor adapted to provide a signal indicative of the temperature of the water downstream of the water heater, wherein the controller is further adapted to determine a volume of water requiring heating from signals indicative of the temperature of the water in the tank from the first, second and third temperature sensors and energise the first pump and the water heater in response thereto, and wherein the controller is further adapted to vary the speed of the energised first pump such that the fourth temperature sensor indicates to the controller that the water at or downstream of the outlet of the instantaneous-type water heater is a substantially constant first predetermined value.

The first predetermined value is about 70 degrees C.

The first temperature sensor is preferably adapted to provide a signal to the controller indicative of the maximum temperature of the water in the tank. The second temperature sensor is preferably adapted to provide a signal to the controller indicative of the volume in the tank above or below a predetermined temperature, for example 50 degrees C. The third temperature sensor is adapted to provide a signal to the controller indicative of the temperature of the water being supplied to the first pump and/or to the water heater.

The water heating system preferably includes: at least one solar panel with an inlet, an outlet and a fifth temperature sensor; and a first diverter valve having: an inlet in fluid communication with the outlet of the first pump; a first outlet in fluid communication with the inlet of the water heater; and a second outlet in fluid communication with the inlet of the solar panel, wherein the outlet of the solar panel is in fluid communication with the second inlet of the tank.

The controller is adapted to: receive from the fifth temperature sensor a signal indicative of the temperature of the water in the solar panel; and a issue control signal to the first diverter valve, wherein, the controller is adapted to control the first diverter valve to direct water to the first outlet of the first diverter valve in response to the fifth temperature sensor indicating that the temperature of the water in the solar panel is about 10 degrees C or more than the temperature of the water at the third (ie. bottom of tank) temperature sensor, and to direct water to the second outlet of the first diverter valve in response to the temperature signal indicating that the temperature of the solar panel is about 4 degrees C or less than the temperature of the water at the third (ie. bottom of tank) temperature sensor.

The water heating system preferably includes: a one way valve adapted to prevent water flow towards the outlet of the solar panel; and a second diverter valve having: an inlet in fluid communication with the second outlet of the first diverter valve; a first outlet in fluid communication with the inlet of the solar panel heater; and a second outlet in fluid communication with atmosphere.

The controller is adapted to: receive from the fifth temperature sensor a signal indicative of the temperature of the water in the solar panel; and issue a control signal to the second diverter valve, wherein the controller is adapted to control the second diverter valve to direct water to the second outlet in response to the fifth temperature sensor indicating that the temperature of water in the solar panel is about 6-8 degrees C or less.

The controller is preferably also adapted to: receive from the fifth temperature sensor a signal indicative of the temperature of the water in the solar panel; and issue a control signal to the second diverter valve, wherein the controller is adapted to control the second diverter valve to direct water to the second outlet in response to the fifth temperature sensor indicating that the water in the solar panel is about 90 degreees C or more.

The controller is preferably also adapted to: receive from the first temperature sensor a signal indicative of the temperature of the water at or near the top of the tank; and issue a control signal to the second diverter valve, wherein the controller is adapted to de-energise the pump in response to the first temperature sensor indicating that the water at or near the top of the tank is about 80 degreees C or more.

Brief Description of the Drawings

Preferred embodiments of the invention will now be described, by way of examples only, with reference to the accompanying drawings in which:

Fig. lisa schematic view of a first embodiment of a water heating system;

Fig. 2 is a schematic view of a second embodiment of a water heating system;

Fig. 3 is a schematic view of a third embodiment of a water heating system;

Fig. 4 is a schematic view of a fourth embodiment of a water heating system;

Fig. 5 is a schematic view of a fifth embodiment of a water heating system; and Fig. 6 is a schematic view of a sixth embodiment of a water heating system.

Detailed Description of the Preferred Embodiments

Fig. 1 shows a first embodiment of a water heating system 10, including a gas instantaneous type water heater 12, preferably of a 4, 5 or 6-star rating. The system 10 also includes a water storage tank 14, preferably 40-50 litres in volume. The tank 14 is encased in insulation (not shown). The tank 14 has a first mains water inlet 16 at or near the bottom of the tank 14. The tank 14 also has a first water outlet 18 at or near the top of the tank 14. The outlet 18 of the tank 14 is connected to a user controlled outlet device, such as a hot water tap (not shown). The inlet 16 is connected to a mains water supply. The heater 12 has an inlet 20 and an outlet 22. The tank 14 also includes a second outlet 24 in fluid communication with the inlet 20 of the heater 12 via pipe 26. The tank 14 also includes a second water inlet 28 in fluid communication with the outlet 22 of the water heater 12 via pipe 30.

The system 10 also includes a controller 32 which is connected to a temperature sensor 34 within the tank 14 and also to the water heater 12, by line 36.

In operation, the controller 32 energises the heater 12 in response to a temperature signal from the sensor 34 indicating that the temperature of the water in the tank is substantially equal to or below a first predetermined value of 50 degrees C. Energising the heater 12 creates a thermo-syphoning action causing heated water to be introduced at or near the top of the tank 14 at the second inlet 28 and cooler water to be withdrawn from the tank 14 at the second outlet 24 for circulation through the heater 12. In this way, hotter water layers are maintained at or near the top of the tank 14 and cooler water layers are maintained at or near the bottom of the tank 14. The heater 12 has a fixed gas energy input and heating output and is simply energised or de-energised (i.e. turned on or turned off) by the controller 32.

Incoming mains water supply is supplied to the coolest water at the bottom of the tank 14 at the first inlet 16, generally at a range of between 5 to 30°C. The hottest water is at the top of the tank 14 and thus available to users via the first outlet 18. This advantageously means that, whilst the water in the tank 14 remains sufficiently heated, the user does not have to wait for cold water to be heated and supplied to them. The system 10 thus provides heated water to the user more quickly than existing systems, thereby reducing the amount of water that is otherwise wasted whilst the user waits for hot water to reach the tap. The system 10 also avoids wasting the gas that would have been used whilst the user waits. The system 10 is also advantageously relatively simple and thus relatively inexpensive to manufacture and operate.

Fig. 2 shows a second embodiment of a water heating system 40. The water heating system 40 is similar to the water heating system 10 shown in Fig. 1 and like features have been indicated with like reference numerals. However, the water heating system 40 includes a pump 42 with an inlet 44 and an outlet 46. The pump inlet 44 is in fluid communication with the second outlet 24 of the tank 14 and the pump outlet 46 is in fluid communication with the inlet 20 of the heater 12. The controller 32 is connected to the pump 44, by line 48. The controller 32 is also connected to a first temperature sensor 54 upstream of the pump 42, by line 56, and to a second temperature sensor 50 downstream of the outlet 22 of the water heater 12, by line 52.

In operation, the controller 32 energises the pump 42 and the heater 12 in response to a temperature signal from the first sensor 54 indicating that the temperature of the water in the tank is substantially equal to or below a first predetermined value of 50 degrees C. The controller 32 also monitors the temperature of the water leaving the outlet 22 of the water heater 12, via the second temperature sensor 50, and adjusts the speed of the pump 42 to ensure that the temperature of the water leaving the water heater 12 is at a second predetermined substantially constant value of, for example, 70 degrees C. Slowing the pump 42 increases the residence time of the water flowing through the water heater 12 and thus increases this temperature and vice versa.

The controller 32 pulses the motor of the pump 42 at a known number of pulses per minute in order to calculate the volume of water pumped through the heater 12. As the controller 32 is monitoring the temperature sensors 50 and 54 about every 10 milliseconds, the adjustment of the speed of the pump 42 is very accurate and fast.

As with the first embodiment, the water heater 12 operates with a fixed energy input and output. The volume of water heated can be the entire volume of the tank 14 or a lesser volume, as determined is required or suitable by the controller 32. The system 40 thus suits relatively small volume tanks where tank temperature sensitivity is not required. As with the first embodiment, the heating action is top-down heating so as to provide hotter water (e.g. 70°C) above the lines 58, and thus adjacent the first outlet 18, and cooler water (e.g. 5 to 30°C) below the lines 58, where colder mains water is introduced. The system 40 advantageously avoids the expense associated with having a temperature sensor in the water tank.

Fig. 3 shows a third embodiment of a water heating system 60. The water heating system 60 is similar to the water heating system 40 shown in Fig. 2 and like features have been indicated with like reference numerals. However, in the water heating system 60, the temperature sensor 54 is omitted and the controller 32 is respectively connected to first, second and third temperature sensors 62, 64 and 66 positioned at or near the top, middle and bottom of the tank 14. The sensors 62, 64 and 66 are respectively connected to the controller 32 by lines 68, 70 and 72. The temperature sensor 50 is retained as a fourth temperature sensor.

The system 60 operates in a similar manner with that described with reference to a system 40, except that the system 60 has the ability to accurately heat a specific volume of water dependent on the decisions made by the controller 32, in response to the temperature of the water in the tank at the three positions provided by the sensors 62, 64 and 66. These three temperatures allow the controller 32 to determine whether or not all or some smaller desired percentage of the volume of the tank 14 is to be heated. This advantageously allows the heated water volume to be determined by user inputs, through the controller 32, or independently by algorithms within the software logic of the controller 32.

The use of three sensors 62, 64 and 66 also enables the system 60 to effectively emulate a two tank system (in which a first tank is used as a preheater and has variable water temperatures dependent on input and a second tank is a boosted tank with a consistent temperature suitable for delivery to the user) with only the (single) tank 14. The use of the single tank 14 advantageously lowers production and installation complexity and cost.

In addition, the first temperature sensor 62 is advantageously able to provide a signal to the controller 32 indicative of the maximum allowable temperature of the water in the tank 14, for example 80 degrees C. The second temperature sensor 64 is advantageously adapted to provide a signal to the controller 32 indicative of the volume in the tank 12 above or below a predetermined temperature, for example 50 degrees C. The third temperature sensor 66 is advantageously able to provide a signal to the controller 32 indicative of the temperature of the water being supplied to the inlet of the pump 42 and/or to the water heater 12.

Fig. 4 shows a third embodiment of a water heating system 80. The water heating system is similar to the water heating system 60 shown in Fig. 3 and like features have been indicated with like reference numerals. However, the water heating system 80 also includes a first diverter valve 82 with an inlet 84, a first outlet 86 and a second outlet 88. The system 80 also includes a solar panel 90 with an inlet 92 and an outlet 94. The inlet 84 of the first diverter valve 82 is in fluid communication with the outlet 46 of the pump 42. The first outlet 86 of the first diverter valve 82 is in fluid communication with the inlet 20 of the heater 12. The second outlet 88 of the first diverter valve 82 is in fluid communication with the inlet 92 of the solar panel 90 via pipe 96. The outlet 94 of the solar panel 90 is in fluid communication with the second inlet 28 of the tank 14 via pipe 98. The first diverter valve 82 is connected to the controller 32 by line 100. The solar panel 90 includes a fifth temperature sensor 102 connected to the controller 32 by line 104.

In operation, the controller 32 can advantageously control the first diverter valve 82 to direct pumped water either through the water heater 12 or through the solar panel 90. Generally speaking, the controller 32 determines whether the water heater 12 or the solar panel 90 are activated in order to best suit expected demands and will always attempt to heat the water using solar energy over gas energy.

More particularly, the controller 32 controls the first diverter valve 82 to direct water to the first outlet 86 of the first diverter valve 82 in response to the fifth temperature sensor 94 indicating that the temperature of the water in the solar panel 90 is about 10 degrees C or more than the temperature of the water at the third (ie. bottom of tank) temperature sensor 66. If the fifth temperature sensor 94 indicates that the temperature of the water in the solar panel 90 is less than about 10 degrees C or more than the temperature of the water at the third (ie. bottom of tank) temperature sensor 66, and the sensors 62, 64, and 66 indicate a falling water temperature in the tank 14, then the controllere energises the pump 42 and the heater 12. The controller 32 also controls the first diverter valve 82 to direct water to the second outlet 88 of the first diverter valve 82 in response to the fifth temperature sensor 94 indicating that the temperature of the solar panel 90 is about 4 degrees C or less than the temperature of the water at the third (ie. bottom of tank) temperature sensor 66.

The system 80 can also emulate a two tank system, in conjunction with the solar panel 90, such that the portion of the tank 14 below the lines 58 acts as a cooler water tank and the portion of the tank 14 above the lines 58 acts as a hotter water tank. The three sensors 62, 64 and 66 allow for accurate positioning of the lines 58 line or, put another way, the volume above the lines 58 can be adjusted from zero to the whole of the tank 14. For example, in a 250 litre tank, a volume of 25-50 litres of water can be maintained at about 70 degrees C to suit expected normal usage.

Fig. 5 shows a fifth embodiment of a water heating system 120. The system 120 is similar to the system 80 shown in Fig. 4 and like components have been indicated with like reference numerals. However, the system 120 includes a second diverter valve 122 and a one-way valve 124. The second diverter valve 122 has an inlet 126 in fluid communication with the outlet 88 of the first diverter valve 82. The second diverter valve 122 also has a first outlet 128, in fluid communication with the inlet 92 of the solar panel 90, and a second outlet 130, which can drain to atmosphere, or for collection for re-use.

In operation, if the controller 32 determines that the ambient temperature is cold enough to freeze water in the solar panel 90, and thus cause damage, then the second diverter valve 122 is controlled to direct water from the inlet 92 to the second outlet 130. This causes the water in the solar panel 90 to drain and empty. Such draining is, for example, in response to the fifth temperature sensor 94 indicating that the temperature of water in the solar panel 90 is about 6-8 degrees C or less. Draining can also be performed to prevent overheating of the solar panel 90, responsive to temperatures measured at the fifth temperature sensor 94. Such draining is, for example, in response to the fifth temperature sensor 94 indicating that the water in the solar panel 90 is about 90 degreees C or more. These draining operations are described in the Applicant’s International PCT Patent Application No. PCT/AU2008/001476 filed 3 October 2008, the relevant contents which are incorporated herein by cross-reference. The one-way valve 24 prevents water draining from the tank 14 through the outlet 130.

In addition, if the controller 32 receives from the first temperature sensor 62 a signal indicative of the temperature of the water at or near the top of the tank 14 is about 80 degrees C or more, the controller 32 issues a control signal to de-energise the pump 42 (to stop water flowing through the solar panel 90).

Fig. 6 shows a fifth embodiment of a water heating system 140. The system 140 is similar to the system 80 shown in Fig. 4 and the system 120 shown in Fig. 5 and like components have been indicated with like reference numerals. However, the system 140 includes a fan coil type, water to air heat exchanger 142, with a fan 143, and a pump 144. The heat exchanger 142 also has an air inlet, adjacent the fan 143, and an air outlet. The heat exchanger 142 has a water inlet 146 in fluid communication with the outlet 148 of the pump 144 via a pipe 145. An inlet 150 of the pump 144 is in fluid communication with the first outlet 18 of the tank 14 via a pipe 151. The heat exchanger 142 has an water outlet 152 in fluid communication with the bottom of the tank 14 via a pipe 153. The system 140 also includes a user operated (ie. in house) display and control unit 154. The display and control unit 154, the pump 144 and the fan 143 are all connected to the controller 32 by lines 156, 158 and 160 respectively. The tempreature in the heat exchanger 142 is monitored by the controller via line 161.

In operation, a user selects heating at the display and control unit 154. This instruction is communicated to the controller 32 which activates the pump 144 to drive heated water, from the top of the tank 14, into the heat exchanger 142. The controller 32 also activates the fan 143 to drive (relatively colder) ambient air 162 into the heat exchanger 142 via the air inlet. The air is heated by the water within the heat exchanger 142, resulting in heated air 164, which is then ducted from the air outlet into the room or rooms required. This process also cools the water in the heat exchanger 142 which is returned to the bottom of the tank 14 via the pipe 153. The speeds of the pump 144 and the fan 143 are adjusted by the controller 32 to deliver the temperature and flow rate of heated air required by the user.

The system 140 can advantageously supply a building’s heating and hot water needs contemporaneously. This avoids multiple plants and saves cost and space. The controller 32 understands if solar energy is available, the heated condition of the tank 14, the temperature of the room or rooms to be heated and the user’s instructions. The building’s heating and hot water needs stimulate (singularly or contemporaneously) energy input into the water heater 12 if there is insufficient energy stored in the tank 14 to satisfy the required energy output. The controller 32 will always attempt to use solar engergy as a preference, to minimise purchased energy (eg. gas), but will defer to other sources (eg. gas) in order to satisfy user requirements. A variation of the system 140 can be used to deliver heated water to a wall mounted fan or heat exchanger/radiator in a room or rooms.

Although the invention has been described with reference to specific examples, it will be appreciated by persons skilled in the art that the invention can be embodied in many other forms. As an example, the gas instantaneous water heaters can be replaced with electric instantaneous water heaters, which results in electrical energy being saved instead of gas energy being saved. Other fuels can also be used in the instantaneous water heater. As another example, valves 82 and 122 can be combined into one valve with numerous inlets/outlets in order to avoid the cost of a second diverter motor. The solar panel or panels can be flat panel type, evacuated tube type or black absorption material type. The water tank can be 50-600 litres in size.

Claims

1. A water heating system comprising: a water storage tank having a top and a bottom; a first mains water tank inlet at or near the bottom of the tank; a first water tank outlet at or near the top of the tank; an instantaneous-type water heater having an inlet and an outlet; a second water tank outlet at or near the bottom of the tank a second water tank inlet in fluid communication with the outlet of the instantaneous-type water heater; a first pump having an inlet and an outlet, the first pump inlet being in fluid communication with the second water outlet and the first pump outlet being in fluid communication with the inlet of the instantaneous-type water heater; a third water tank inlet at or near the bottom of the tank; a heat exchanger having a water inlet, a water outlet, an air inlet and an air outlet, the heat exchanger water outlet being in fluid communication with the third water tank inlet; a second pump having an inlet and an outlet, the second pump inlet being in fluid communication with the first water tank outlet and the second pump outlet being in fluid communication with the heat exchanger water inlet; a user control input device; and a controller, wherein, in response to a user input to the user control input device, the controller energises the second pump to drive water through the heat exchanger.

2. The system as claimed in claim 1, wherein the heat exchanger includes a fan adapted to drive air through the heat exchanger, for heat exchange with the water being driven therethrough, and the controller energises the fan and the second pump together.

3. The system as claimed in claim 2, wherein the controller is further adapted to vary the speed of the energised second pump and of the fan in order to control the temperature and flow rate of the air leaving the heat exchanger.

4. The system as claimed in claim 1, 2 or 3, wherein the water heating system includes a tank water temperature sensor and the controller is further adapted to energise the instantaneous-type water heater in response to the tank water temperature sensor indicating to the controller that the temperature of the water in the tank is substantially equal to or below a first predetermined value.

5. The system as claimed in claim 4, wherein the first predetermined value is about 50 degrees C.

6. The system as claimed in claim any one of claims 1 to 5, wherein the water heating system includes a temperature sensor.

7. The system as claimed in claim 6, wherein the temperature sensor is at or near the bottom of the tank.

8. The system as claimed in any one of claims 1 to 7, wherein the instantaneous-type water heater has a fixed power output.

9. The system as claimed in claim 1, 2 or 3, wherein the system also includes a first water temperature sensor adapted to provide a first signal indicative of the temperature of the water upstream of the first pump; and a second water temperature sensor adapted to provide a second signal indicative of the temperature of the water downstream of the water heater, wherein the controller is further adapted to energise the first pump and the water heater in response to the first temperature sensor indicating to the controller that the temperature of the water upstream of the first pump is substantially equal to or below a first predetermined value, and wherein the controller is further adapted to vary the speed of the energised first pump such that the second temperature sensor indicates to the controller that the water at or downstream of the outlet of the instantaneous-type water heater is a substantially constant second predetermined value.

10. The system as claimed in claim 9, wherein the first predetermined value is about 50 degrees C.

11. The system as claimed in claim 9 or 10, wherein the second predetermined value is about 70 degrees C.

12. The system as claimed in any one of claims 1 to 11, wherein the instantaneous-type water heater has a fixed power output.

13. The system as claimed in any one of claims 1 to 12, wherein the controller monitors the first pump to thereby determine the volume of pumped water.

14. The system as claimed in claim 13, wherein the first pump preferably includes a motor.

15. The system as claimed in claim 14, wherein the motor is controlled by pulsing, whereby the revolutions per minute are monitored and thus the pumped volume calculated.

16. The system as claimed in claim 15, wherein the controller has an embedded algorithm such that the pulsing is altered relative to the incoming water temperature and the outgoing water temperature.

17. The system as claimed in claim 14, wherein the revolutions per minute of the motor are monitored with a tachometer to calculate pumped volume.

18. The system as claimed in claim 1, 2 or 3, wherein the water heating system further includes: first, second and third temperature sensors at or near the top, middle and bottom of the tank respectively; and a fourth water temperature sensor adapted to provide a signal indicative of the temperature of the water downstream of the water heater, wherein the controller is further adapted to determine a volume of water requiring heating from signals indicative of the temperature of the water in the tank from the first, second and third temperature sensors and energise the first pump and the water heater in response thereto, and wherein the controller is further adapted to vary the speed of the energised first pump such that the fourth temperature sensor indicates to the controller that the water at or downstream of the outlet of the instantaneous-type water heater is a substantially constant first predetermined value.

19. The system as claimed in claim 18, wherein the first predetermined value is about 70 degrees C.

20. The system as claimed in claim 18 or 19, wherein the first temperature sensor is adapted to provide a signal to the controller indicative of the maximum temperature of the water in the tank.

21. The system as claimed in claim 18, 19 or 20, wherein the second temperature sensor is adapted to provide a signal to the controller indicative of the volume in the tank above or below a predetermined temperature

22. The system as claimed in claim 21, wherein the predetermined temperature is 50 degrees C.

23. The system as claimed in any one of claims 18 to 22, wherein the third temperature sensor is adapted to provide a signal to the controller indicative of the temperature of the water being supplied to the first pump and/or to the water heater.

24. The system as claimed in any one of claims 1 to 23, wherein the water heating system includes: at least one solar panel with an inlet, an outlet and a fifth temperature sensor; and a first diverter valve having: an inlet in fluid communication with the outlet of the first pump; a first outlet in fluid communication with the inlet of the water heater; and a second outlet in fluid communication with the inlet of the solar panel, wherein the outlet of the solar panel is in fluid communication with the second inlet of the tank.

25. The system as claimed in claim 24, wherein the controller is adapted to: receive from the fifth temperature sensor a signal indicative of the temperature of the water in the solar panel; and a issue control signal to the first diverter valve, wherein, the controller is adapted to control the first diverter valve to direct water to the first outlet of the first diverter valve in response to the fifth temperature sensor indicating that the temperature of the water in the solar panel is about 10 degrees C or more than the temperature of the water at the third temperature sensor, and to direct water to the second outlet of the first diverter valve in response to the temperature signal indicating that the temperature of the solar panel is about 4 degrees C or less than the temperature of the water at the third temperature sensor.

26. The system as claimed in claim 24 or 25, wherein the water heating system includes: a one way valve adapted to prevent water flow towards the outlet of the solar panel; and a second diverter valve having: an inlet in fluid communication with the second outlet of the first diverter valve; a first outlet in fluid communication with the inlet of the solar panel heater; and a second outlet in fluid communication with atmosphere.

27. The system as claimed in claim 24, 25 or 26, wherein the controller is adapted to: receive from the fifth temperature sensor a signal indicative of the temperature of the water in the solar panel; and issue a control signal to the second diverter valve, wherein the controller is adapted to control the second diverter valve to direct water to the second outlet in response to the fifth temperature sensor indicating that the temperature of water in the solar panel is about 6-8 degrees C or less.

28. The system as claimed in claim 27, wherein the controller is also adapted to: receive from the fifth temperature sensor a signal indicative of the temperature of the water in the solar panel; and issue a control signal to the second diverter valve, wherein the controller is adapted to control the second diverter valve to direct water to the second outlet in response to the fifth temperature sensor indicating that the water in the solar panel is about 90 degrees C or more.

29. The system as claimed in claim 28, wherein the controller is also adapted to: receive from the first temperature sensor a signal indicative of the temperature of the water at or near the top of the tank; and issue a control signal to the second diverter valve, wherein the controller is adapted to de-energise the pump in response to the first temperature sensor indicating that the water at or near the top of the tank is about 80 degrees C or more.