Technical Field This invention relates to water saving in a domestic, industrial or commercial hot water service. It also relates to the provision of a temperature controlled water service in such environments..

Background Art

From time to time problems arise in various areas and localities as a result of localised drought conditions which place a restriction on the available water supply, causing local instrumentalities to introduce and enforce restrictions as to water usage. Although taken by many in our modern societies to be an unlimited resource, good available water of the necessary quality suitable for drinking and other human uses should perhaps be regarded as a more precious resource than it often is and not taken so lightly for granted. Even though many persons might regard the supply of water as free,. modern societies demand a quality of water which places an ongoing burden on instrumentalities to ensure those conditions are maintained, and as a result there is a cost associated therewith. Aside from the need to conserve water as a basic life . sustaining necessity, water wastage has its own economic consequences.

Instrumentalities may therefore introduce specific restrictions such as limitations on the way in which households and businesses use water, for example by limiting the number of hours in which people may hose gardens, or use watering systems etc. Instrumentalities may also limit the types of water usage, for example, by restricting the hosing of hard surfaces and so on, encouraging any washing to be dorie over grass areas etc, in order to limit water wastage by simple run-off into drains and the like.

However, underlying all water restrictions is the general notion of avoiding unnecessary water wastage. To this end, householders and businesses are encouraged to avoid water wastage by ensuring for example that taps are in good condition, as a leaking tap can waste more water unknowingly than a deliberate use or even abuse of an amount of water which one uses intentionally. In this context it will thus be appreciated that perhaps one unrealised and unexplored area of water wastage in household and domestic hot water services which occurs constantly in our daily routines, arises when a user turns on the hot water tap and waits while the system comes to the desired temperature, for example in running a shower or in many other usage situations. This follows because the "hot" water in the hot water line, ie between the hot water tank and the hot outlet, will have cooled since the hot water tap was last in use. Very often the colder or at least cooler water which first issues, is simply allowed to run down the sink or drain and is thus wasted.

Although this might seem like only a small volume of water on each occasion, the combined effect, multiplied by the number of times an individual might thus waste water throughout the day and then multiplied by the number of individuals in a community, the volume o(f water thus wasted may be regarded as anything but inconsequential.

Object of the Invention

It would therefore be advantageous if there were an effective means of reducing water wastage arising from the use of a hot water service, during the time in which the temperature rises to the desired temperature at the outlet for the water service. Such a system should be simple and not only available for new installations but ideally should be capable of fitment to existing hot water services economically and with as little disruption to existing facilities as possible. It would also be advantageous if such a system also provided overall control of both the flow rate and temperature of water at the outlet.

At the very least the following disclosure provides an alternative to present means of eliminating or reducing water wastage in domestic and commercial hot water services.

Disclosure of the Invention

According to the present invention, there is provided a water saving system for use in conjunction with one or more temperature controlled outlets for a domestic or commercial hot water service having a hot water line and a cold water line for the delivery of hot and/or cold water to a mixer outlet, in which computer controlled flow switches are located in each of the hot water and cold water lines adjacent to or in the vicinity of the mixer outlet to control the combined flow of hot and cold water delivered at the outlet at a predetermined temperature and flow rate, and wherein a water saving or return line is utilised in the service in addition to the conventional hot and cold water lines; the water saving or return line being connected between the flow switch located in the hot water line and the cold water infeed to the hot water tank, either directly or by means such that a portion of the existing cold water plumbing facility is utilised to create a return path; the return line further having a flow pump located therein; the flow switches being regulated by the computer so as to control the flow of hot water and cold water therethrough to deliver water at a predetermined temperature and flow rate at the mixer based on the measured temperature in each line, and in the case of the flow switch in the hot water line, directing the water therein to return via the return line to the hot water tank by means of the flow pump located in the return line until such time as the temperature in the hot water line reaches a temperature capable of satisfying the predetermined temperature required at the outlet, at which time it then directs the water in the hot water line to the outlet, the flow switch in the cold water line being also turned off until that time or until cold water is otherwise required.

Preferably a pressure control device ensures constant pressure for both the cold and hot water lines. The advantage of this lies in then being able to provide the correct mix of hot and cold water at the mixer to satisfy the tempefature called for. Thus it will be preferable to have a means to control the mains pressure so as to be able easily to control the overall functioning and operation of the system.

It will thus be appreciated that rather than having a conventional tap or faucet, the mixer outlet will be controlled by means of a control device in the form of a control panel for a computer for example, where the desired temperature and flow rate may be entered. In this regard it should be understood that the invention is not limited to a computer controlled outlet, where the control device is remote from the outlet, but may include a "computerised tap" where the flow rate and/or temperature may be adjusted directly at the outlet. In other words, the control device maybe a panel which is independently located with respect to the outlet, or may be integrated therewith.

Once the desired temperature and flow rate are entered, then the control device may be set to "on" for delivery of water at that temperature and at that flow rate. Not until the desired temperature is reached at the flow switch in the hot water line will the water from either line be allowed to flow to the mixer outlet. Preferably the control device will also allow for further adjustment of the temperature and flow rate during the time the water is flowing from the outlet as well as providing for turning the flow off altogether.

During the time the flow pump is operational, ie causing the water in the return line to be returned or recycled to the hot water tank, it will be preferred to have the mains pressure infeed interrupted, for example by means of a mains pressure flow switch acting in conjunction with the flow switches in the hot and cold water lines.

Preferably means to determine the temperature in the both the hot and cold water lines is provided by a temperature sensing device located in each line adjacent or in the vicinity of the flow switch in that line, and on the infeed side thereof.

Optionally, a temperature sensing device may also be employed at the mixer outlet itself to allow control of the temperature of the water delivered at that outlet, rather than being determined merely by the temperature of the water in the hot water line itself as described above.

It will be appreciated that in new dwellings and buildings this system may be readily implemented by the use of a separate and thus independent water pipe from the flow switch installed in the hot water line directly to the hot water tank. This will be the most efficient system for a new dwelling. In this system, there is no interference with the cold water portion of the system. On the other hand, in existing dwellings and buildings, where major reinstallation of the plumbing system are not intended, nor indeed maybe practicable, it is possible instead, to use the existing cold water pipes to return water which has not yet reached the desired temperature in the hot water line, to the hot water tank. In this case, the water saving return line is short and connects directly back into the cold water line making it less efficient as this effectively puts some hot (or at least warm) water into the cold water line. For example, the short connecting line may be conveniently located immediately behind the outlet mixer. This system is less desirable, but is a compromise for existing dwellings. Each dwelling must be assessed for the best system based on cost and practicality.

In existing dwellings where the return flow line is connected to the infeed of the hot water tank by means of the existing cold water line, it will be understood that the flow switch and mains pressure in the cold water line will need to be simultaneously controlled with the hot water line to allow the return path to function.

In either case, a temperature and flow control device or panel is preferably used to control the flow switches and flow pumps in the respective lines.

It will also be readily appreciated that this system may be employed for multiple mixer outlets, where individual flow switches are installed in each of the hot and cold lines at each outlet, and where individual return lines are connected in known fashion to return the cooler water which has not yet reached the predetermined temperature to the infeed of the hot water tank via the flow pump. Individual control devices or panels will be thus utilised at each mixer outlet.

In addition, a master controller may be employed to limit the overall temperature that the system is capable of delivering, so that at no time water hotter than a predetermined temperature will be delivered at any outlet. This would be particularly useful for example in households where there are small children, as it would limit the possibility of serious injury arising from scalding hot water being delivered at any outlet. Brief Description of the Drawings The invention may be better understood from the following non-limiting description of preferred embodiments, in which:

Figure 1 is a schematic diagram showing one outlet of a water saving and temperature controlled water service utilising an independent return line to the water heater for water in the hot water line which has not yet reached a required temperature; Figure 2 is a schematic diagram of a water service comprising several outlets of the type depicted in Fig 1; Figure 3 is a schematic diagram showing one outlet of an alternate water saving and temperature controlled water service utilising a portion of the cold water line as the return path to the hot water heater for water in "the hot water line which has not yet reached a required temperature; and Figure 4 is a schematic diagram of a water service comprising several outlets of the type depicted in Fig 3. Detailed Description of the Drawings Turning to Figure 1, there is shown a water saving system generally referenced 11 which comprises a mixing unit 12 leading to an outlet 13 for supplying amix of hot and cold water as required. The mixing unit 12 is fed by a cold water line 14 and a hot water line 15. The cold water line 14 is fed by so-called mains pressure and is a direct feed from the water meter 16 to the mixing unit 12, ie from the point at which the dwelling or building is connected to the external water supply from the local instrumentality. The hot water line 15 connects from the outlet 17 of the hot water tank 18 to the mixer 12. A branch line 19 from the cold water line 14 is connected to the inlet 20 of the hot water tank 18. A mains pressure flow switch 21 is provided in the branch line 19 to ensure control of the water pressure to the hot water tank 18. Flow switches 22 and 23 are located in each of the respective cold and hot water lines 14, 15 adjacent or in the vicinity of the mixing unit 12. Just prior to each of the flow switches 22, 23, ie on the infeed side thereof, there are located temperature sensing devices 24 and 25 for each of the cold and hot water lines 14, 15 respectively. The δ temperature sensing devices 24, 25 may be integrated with each of the corresponding flow switches 22, 23, or may be independent thereof.

A return line 26 for water in the hot water line 15 which has not reached a required temperature, is connected between the flow switch 23 in the hot water line 15 and the hot water tank 18 via a flow pump 27.

o A computer operated control device (not specifically illustrated), in this case having a control panel generally referenced 28 has a number of buttons marked as shown in Fig 1 , and is provided to control the overall flow of hot and cold water in the respective lines 14 and 15, ie by means of controlling the flow switches and pumps 22, 23 and flow pump 27, so that only water at the required temperature and at a s desired flow rate is delivered from the mixer 12 to the outlet 13. The control panel 28 receives information from and continually monitors the sensors 24 and 25 to establish the correct parameters for the flow switches 22, 23 and flow pump 27, to ensure that only water at the correct temperature and flow rate is delivered at the outlet 13. This includes diverting the flow of water in the hot water line 15, back to the water tank 18, until such time as the temperature in the hot water line 15 is sufficient to ensure that water having the desired temperature can be delivered at the outlet 13. During this time the water will also be prevented from flowing in the cold water line 14 to the mixer 12.

The direction of flow of water in each of the respective lines 14, 15 and 26 is indicated by the arrows as shown.

Thus in operation, adjustment of the required water pressure is made by selecting the "buttons" named "Flow Rate Up" or "Flow Rate Down" either at the control panel 28 as depicted in Fig 1 or at a computerised "tap" or outlet. The indicator shown in the panel 28 and labelled "Flow" adjusts to show the level of water flow. To achieve the desired temperature, the user selects either the button labelled "Hotter" or "Colder" until the "Desired temperature" is thus indicated in the panel or window labelled thus.

5 Once the desired temperature and flow rate have been set, it is a simple matter to select the "On" button and the water will be caused to flow at the selected rate and temperature.

Adjustments can also be made as the water is running.

If the user runs out of hot water, pressing the "Hot tap only" button will cause the hot 10 water only to flow until the water becomes cold.

When finished, the user touches the "Off button and the flow of water will cease. Once functioning, if the hot water is about to run out, the system can be utilised to warn the user and can automatically switch to hot water only so that the outlet, for example a shower, does not stop mid-stream.

15 Pressing the "Hot tap only" button causes the water delivered at the outlet 13 to be at the temperature in the hot water tank 18.

Conversely, pressing the "Cold tap only" button causes the water at the outlet 13 to be at the temperature in the cold water line 15.

Thus, in operation, when the hot water is switched on, the mains pressure flow switch 20 21 is automatically in the off position. The hot water flow switch 23 is automatically in the position to return the water back to the hot water tank 18 utilising the flow pump 27 located in the return or water saving line 26.

This will continue until the water reaches the desired temperature measured by the hot water temperature measuring device 25, the computer then controls both the hot 25 and cold flow switches 22, 23.

The computer continually calculates and adjusts for the "desired temperature" and "flow" rate, by using the information gathered from the hot water temperature measuring device 25 and the cold water temperature measuring device 24. Although not specifically shown, this information may be augmented by utilising a third sensor located in the mixing unit 12 to confirm that the required temperature has been met for delivery to the outlet 13.

Using this system there will be no hot or cold water coming out of the spout or outlet 13 until the desired temperature and flow rate requested is achievable. When the water comes out of the spout or outlet 13, cold water is then released by the main pressure flow switch 21 into the hot water tank 18, the water no longer being diverted from the hot water line 15 to the tank 18. If the temperature of the water in the hot water tank 18 is not as hot as the "desired temperature", no water will come out of the outlet 13 until the "desired temperature" is lowered to that temperature in the hot water tank 18. If the user runs out of hot water, pressing the hot water only button will cause the hot water to flow until the water becomes cold, The connection to the line for the next cold outlet is shown at item 41, and to the line for the next hot water outlet at item 42.

Turning to Fig 2, there is depicted diagrammatically a water service for a household, based on the embodiment shown in Fig 1, there being several outlets associated for example with a kitchen 31 , bathroom 32 and en-suite bathroom 33. The various components are referenced with the same reference numerals as in Fig 1.

Essentially each outlet 13 requiring both hot and cold water has in addition to standard plumbing for that purpose, a computer controlled mixer unit of the type described above (not specifically shown), and a water saving return line 26 allowing water which has not yet reached a sufficient temperature in the respective hot water line 15 to be diverted. back to the hot water tank 18. A central "maximum control switch" 34 may be incorporated to ensure that water cannot be delivered over and above a maximum safe temperature. Figures 3 and 4 depict an embodiment of the invention for existing dwellings where it is not practicable to utilise an independent return line as described in relation to the embodiment of Figs 1 and 2. Here again however, like components to those described above utilise the same reference numerals.

The major difference between the embodiment illustrated in Fig 3 when compared to that Figure 1 , is that the direct return line 26 which extends back to the hot water tank 18 in Fig 1 , is here replaced with a short return line 36, which connects from the flow switch 23 located in the hot water line 15 to the nearest convenient point 37 in the cold water network, thereby causing a portion of the existing cold water plumbing to provide the return path. In this case, the mains pressure flow switch 21 is located nearer the water meter 16 to control the overall pressure in the system.

In this case, when the hot water is switched on, the mains pressure flow switch 21 is automatically in the off position. The hot water flow switch 23 is automatically in the position to return the water back to the hot water tank 18 using the flow pump 27 located in a portion of the cold water line 14, into which the short return or water saving line 36 is connected. Thus the flow of water in portions of the cold water line 15 will be in reverse flow to normal as indicated in relevant portions of cold water line 14 as shown in Fig 3.

This procedure will continue until the water in the hot water line 15 reaches the desired temperature measured by the hot water temperature measuring device 25, the computer then once again controlling both the hot and cold flow switches 22, 23.

The computer calculates the "desired temperature" by using information gathered from the "flow rate", hot water temperature measuring device 25 and the cold water temperature measuring device 24.

Again, using this system there will be no hot or cold water coming out of the spout 13 until the desired temperature and flow rate requested is achievable. When the water comes out of the spout 13, cold water is then released by the main pressure flow switch 21 into the hot water tank 18. If the hot water tank 18 is not as hot as the "desired temperature" no water will come out of the spout 13 until the "desired temperature" is lowered to the temperature in the hot water tank 18. If a user runs out of hot water, pressing the hot water only button will cause the hot water to flow until the water becomes cold.

Fig 4 shows the overall layout of the system in an existing swelling utilising the arrangement depicted in Fig 3. For simplicity the short return lines 36 are not shown, the cold water line 14 being utilised as discussed above in relation to Fig 3.

Each hot water outlet 13 can be individually adjusted to save water and will start at the temperature selected. Also each hot water outlet 13 can be individually adjusted to a maximum temperature for the safety of children so they can not be scolded utilising the central safe temperature control switch 34.

It will be appreciated by those skilled in the art that many modifications and variations may be made to the embodiments described herein without departing from the spirit or scope of the invention.

Throughout the specification the word "comprise" and its derivatives are intended to have an inclusive rather than exclusive meaning unless the context requires otherwise.