WO2008123785A1

WO2008123785A1 - Improvements in and relating to fluid systems

Info

Publication number: WO2008123785A1
Application number: PCT/NZ2008/000078
Authority: WO
Inventors: Chris Edward King
Original assignee: Saveh20com Ltd
Current assignee: Saveh20com Ltd
Priority date: 2007-04-10
Filing date: 2008-04-10
Publication date: 2008-10-16
Anticipated expiration: 2009-10-10
Also published as: AU2008236933A1; AU2008236933B2

Abstract

A fluid system including a fluid supply (2), at least one outlet and associated outlet control device, said outlet control device (3) operable between open and closed positions to respectively permit and block passage of fluid from said outlet; a supply conduit (4) connecting the fluid supply to said outlet; a return conduit (6) connected to said fluid supply (2); a return valve (7) located proximate and connected to said outlet, said return valve (7) being connected to the supply (2) and return conduits (6), the return valve (7) configured to be capable of moving between a dispensing configuration, permitting fluid passage from the supply conduit (4) to the outlet and blocking fluid passage to the return conduit (6); and a recirculation configuration, permitting fluid passage from the supply conduit (4) to the return conduit and blocking fluid passage to the outlet; a controller (13) capable of controlling said return valve (7) to control the direction of fluid, said controller (13) coupled to a sensor (14) in the supply conduit (4) or return valve (7), said sensor capable of detecting a parameter of interest in the fluid within said supply conduit or return valve (7); and a flow switch (15) coupled to the supply conduit (6) and/or return valve (7); and wherein said flow switch is configured to close an electrical circuit when the fluid flow within said supply conduit (4) reaches a predetermined flow-rate, the closed circuit providing electrical power to said controller (13), and wherein said controller (13) is suitably programmed such that upon said sensor (14) relaying that said parameter of interest meets a predetermined parameter value (7), the controller (13) operates the return valve (7) to move to either the recirculation or dispensing configuration.

Description

00078

IMPROVEMENTS IN AND RELATING TO FLUID SYSTEMS

STATEMENT OF CORRESPONDING APPLICATIONS

This application is based on the Provisional specification filed in relation to New Zealand Patent Application Number 554423 the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to improvements in and relating to fluid systems.

In particular, the present invention relates to a system for minimising the wastage of water from hot water systems.

BACKGROUND ART

The present invention has particular application to hot water systems though this should not be seen to be limiting as the principles of the present invention may have application to other fluid systems.

For ease of reference only, the present'invention will now be described with reference to hot water systems.

Water conservation is particularly important in situations where there is a limited water supply. For example, water conservation is particularly important in mobile applications such as mobile homes, ships and boats, caravans, aircraft and other vehicles.

Limiting wastage of water is also a major concern, not only in arid geographical regions but also, due to rising supply infrastructure costs, in cities and regions with abundant water supplies. Increasing residential, industrial, agricultural and horticultural, water use also places strain on the water supply infrastructure.

A major water use by modern societies is hot water for showers, bathing, cooking, cleaning and the like. Typically hot water is supplied from a hot water tank to a controlled outlet tap via a line from the hot water tank to each tap. However, this configuration leads to a cooling of a body of water (known as a 'slug') which is situated in the line between the tap and hot water tank during periods of non-use. Thus, a user requiring hot water must generally first purge the line of the cold water slug before receiving hot water. This purged water is typically passed to an outlet or waste drain and is generally not utilised. In mobile applications, such as vehicles, this wasted water may represent a significant portion of the water-carrying capacity of the vehicle and thus for a given volume of water for usage, a larger storage tank is required. This represents a higher cost to the user.

Thus, the present invention may have particular application to hot water systems where the source of the hot water is not immediately adjacent to the hot water outlet.

One system that alleviates this problem is described by Stephen et al. in New Zealand Patent No. 239664. Stephen et al. discloses a hot water system that constantly cycles hot water from the hot water tank about a closed loop pipe that has outlet valves attached thereto. The hot water may be cycled through a thermo-siphon effect or via a pump. A constant supply of hot water is thus provided to the outlets while any pathogens in the water slug contained in the loop are killed by the heat therein. However, the Stephen et al. device has a significant disadvantage in that there is a substantial amount of energy used to maintain the temperature of the hot water slug in the pipe in addition to the energy used to cycle the water.

Various other systems have been developed to remove the cold water slug from the line while passing hot water to the outlet and are exemplified by the system described in AU 2005/203025 by Willsford and Murray.

Willsford and Murray describe a water recovery system which includes a hot water tank, an outlet tap and a cold water supply. A thermostatic diverter valve at the tap only permits water to travel out of the tap when the temperature of the water flowing through valve to a re-circulation pipe is within a pre-determined temperature range. The cold water slug passing through the re-circulation pipe is passed to a holding tank.

Similar systems are described in WO 2006/058392 by Winn, Japanese Patent Application No. 2004-287321 by Nakamura et al, and Canadian Patent No. 2252350 by Karmel and Karmel.

WO 2006/058392 by Winn describes a water saving device that uses a controller and two temperature controlled valves, the first of which allows passage of the cold water 00078

slug into a holding tank until hot water enters the pipe to the outlet wherein the first valve closes and the second valve opens to allow hot water to pass to the outlet. The cold water in the storage tank may be mixed with the hot water via a siphon valve arrangement before flowing to the outlet. While the Winn system effectively recycles the cold water slug, the controller must be continuously on to detect the. temperature and water flow in the supply conduit. Thus, in mobile homes, boats and other mobile applications, the battery electricity supply may be drained.

Japanese Patent Application No. 2004-287321 by Nakamura et al describes a water diversion system which includes a temperature controlled valve that allows passage of the cold water 'slug' in the hot water outlet pipe to pass to a storage tank or cold water outlet and closes when the water in the hot water outlet pipe reaches a predetermined temperature. Thus, only hot water is permitted to pass from the hot water outlet.

Canadian Patent No. 2252350 by Karmel and Karmel describes a hot water re- circulation system including a cold water supply pipe, a hot water supply pipe and a temperature dependent diverter valve which permits only hot water in the hot water outlet pipe to travel to a hot water outlet. The cold water 'slug' in the hot water outlet pipe is thus passed to a storage tank and subsequently may be used to supply cold water to the outlet or alternatively may pass to another outlet for alternative uses.

What the above prior art systems share in common a holding tank to which the cold water slug is passed before hot water may be passed to the outlet. These holding tanks may be useful in providing filtration and/or holding potentially unclean water and are essential to the workings of the prior art systems. However, the holding tanks occupy a substantial amount of space which may not be available in space-restricted applications such as water supplies on vehicles. Furthermore, there is additional expense and manufacturing complexity in providing holding tanks and the necessary valves and piping.

Another known method of purging the cold water slug involves use of a redirection line with a valve that is opened for a predetermined period of time to purge the cold water slug through the redirection line. Such timer purge systems require a user to press a button or switch to open the valve and an electrical or mechanical timer then closes the valve after a preset time. Once the valve is closed the user can then open the outlet tap to receive hot water. 00078

Another known adaptation of such a purge system utilises a manual valve that can be opened or closed by the user, requiring the user to judge the appropriate purge time.

The aforementioned purge systems can prove inconvenient as the cold water slug can only be purged through manual user activation. Thus, it is up to the user to remember to purge the slug.

It would thus be advantageous to provide an improved water saving system having a hot water supply or tank and a hot water outlet and a line connecting same, capable of one or more of:

- reducing the quantity of cold water in the line (i.e. the slug) passing to the hot water outlet;

- automatically redirecting cold water (i.e. the slug) to the fluid supply;

- ensuring that a majority of water passed to the hot water is of a predetermined temperature;

minimising manufacturing complexity and cost;

- minimising space requirements; and/or

minimising possibility of failure.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein; this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

It is acknowledged that the term 'comprise' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or 78

elements. This rationale will also be used when the term 'comprised' or 'comprising¹ is used in relation to one or more steps in a method or process.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION

According to a first aspect of the present invention there is provided a fluid system including:

- a fluid supply,

- at least one outlet and associated outlet control device, said outlet control device operable between open and closed positions to respectively permit and block passage of fluid from said outlet;

- a supply conduit connecting the fluid supply to said outlet;

- a return conduit connected to said fluid supply;

- a return valve located proximate and connected to said outlet, said return valve being connected to the supply and return conduits, the return valve configured to be capable of moving between:

o a dispensing configuration, permitting fluid passage from the supply conduit to the outlet and blocking fluid passage to the return

^■ conduit; and

o a recirculation configuration, permitting fluid passage from the supply conduit to the return conduit and blocking fluid passage to the outlet;

- a controller capable of controlling said return valve to control the direction of fluid, said controller coupled to a sensor in the supply conduit or return valve, said sensor capable of detecting a parameter of interest in the fluid Within said supply conduit or return valve; and - a flow switch coupled to the supply conduit and/or return valve; and

wherein said flow switch is configured to close an electrical circuit when the fluid flow within said supply conduit reaches a predetermined flow-rate, the closed circuit providing electrical power to said controller, and

wherein said controller is suitably programmed such that upon said sensor relaying that said parameter of interest meets a predetermined parameter value, the controller operates the return valve to move to either the recirculation or dispensing configuration.

For ease of reference only, the present invention will now generally be described in relation to a hot water fluid supply. However, this should not be seen as limiting as the present invention may also be used with gases, flowable particulate, other liquids or any other fluid.

The outlet control device preferably takes the form of one of various valves commonly found on taps, faucets and the like. Closing of such a valve thus prevents any fluid passage therethrough and therefore also fluid passage through the return valve to the outlet when in the dispensing configuration.

In preferred embodiments, a flow switch is provided in the supply conduit and configured to open or close an electrical circuit depending on the fluid flow-rate in the supply conduit, i.e. the flow switch may open or close when the flow-rate is respectively below and above a predetermined value. The circuit preferably provides electrical power to the controller when the circuit is closed. The controller may thus only use power when fluid flows in the supply conduit (e.g. when opening the outlet) and thereby minimises power consumption. Such a 'normally off' controller is thus particularly suited to mobile applications (e.g. mobile homes and the like) which have a limited power supply.

The flow switch may include any of many known flow switches or sensors and by way of example may include one or more mechanical, acoustic, inductive, electrical or thermal flow switches or sensors. It should be appreciated that in some embodiments the flow switch may incorporate a power supply to operate a sensor, e.g. an acoustic sensor and in such embodiments the controller preferably does not draw power from said flow switch power supply. Preferably, the controller is configured to reset the flow switch to open the circuit to cut power to said controller when said return valve moves from said recirculation configuration to said dispensing configuration. The controller thus only draws power during the time between:

- operation of the outlet control device to permit fluid flow, thus triggering flow switch, and

- detection of the fluid reaching the predetermined parameter value, e.g. the time for a slug of cold water to be purged from the outlet.

Preferably, the return valve is configured to move to the dispensing configuration when the outlet control device is closed. Thus, when the outlet control device is opened, the fluid in the supply conduit will initially flow toward the outlet, triggering the flow switch to thereby close the circuit and provide power to the controller. The controller once activated can then control the direction of fluid flow from the supply conduit to either the outlet or return conduit.

In preferred embodiments, the controller is configured to actuate the return valve to either the recirculation or dispensing configuration upon a parameter of interest of the fluid in the supply conduit reaching a predetermined value.

It is envisaged the parameter of interest may be one or more of any number of fluid parameters, including, but not limited to:

- pressure;

- flow-rate;

- density;

- composition;

- chemical/mineral content;

- radioactivity; or

- other detectable fluid condition. In preferred embodiments, the parameter of interest is the fluid temperature and the parameter value triggering actuation between the recirculation and dispensing configurations is a predetermined threshold temperature. It should be appreciated that the 'threshold temperature' need not be a single temperature and may include a temperature range.

Preferably, the return valve may be actuated to move between the recirculation and dispensing configurations upon receiving a temperature-dependant signal from a temperature sensor in thermal contact with the fluid in said supply conduit and/or return valve.

It will be appreciated by one skilled in the art that various temperature sensor and actuation mechanisms may be employed in the present invention and by way of example may include one or more of: thermocouples, bimetallic switches, thermometer switches, thermal expansion switches, thermistors or the like.

Preferably, the temperature sensor is in thermal contact with the supply conduit in 'close' proximity to the return valve to thereby provide a temperature-dependant signal based on the temperature of the fluid near the outlet.

Preferably, the controller is capable of being programmed by the user to adjust said threshold temperature. A user may thus vary the temperature of the fluid that is passed from the outlet.

In one embodiment, the controller may be configured to pass a temperature- dependant signal to a display to indicate to a user the temperature of said fluid. Such a display may allow a user to monitor the temperature of the fluid and obviate the need for a user to touch the fluid or outlet tap to determine the temperature.

Preferably, when the controller is activated by the flow switch and receives a signal from the temperature sensor indicating the fluid temperature, the controller actuates said return valve to:

the recirculation configuration when said fluid temperature is below a threshold temperature, and

the dispensing configuration when said fluid temperature is equal to, or greater than, said threshold temperature. The controller preferably requires input from a temperature sensor to determine where the return valve will direct the water. For example, if the temperature sensor determines water is below a predetermined temperature (i.e. 'cold'), the return valve will divert water to the fluid supply via the return conduit, whereas if the temperature sensor detects the water is above said predetermined temperature (i.e.. 'hot'), water will be directed to the outlet via the return valve.

The outlet may appear in a variety of different forms, for example, a tap, mixer tap or shower rose. It will be appreciated that where a mixer tap is provided the controller may also be configured to open/close a valve in the cold water supply conduit connected to the mixer tap to thus permit/block water from either the cold or hot water supply conduits from exiting the tap until the water in the hot water supply conduit has reached a predetermined temperature.

In general the outlet control device may be a tap or other device capable of being operated between open and closed positions by a user requiring hot water from the outlet.

The fluid supply may also come in a variety of different forms. In one preferred embodiment the fluid supply includes a hot water tank (also known as a hot water cylinder) and a cold water supply line to the hot water tank.

In other preferred embodiments the fluid supply may be in the form of a 'mains' supply line together with a heater element which is not immediately adjacent a hot water outlet.

In one preferred embodiment, the return conduit is connected directly to the fluid supply. The fluid system thus ensures that the re-circulated fluid is passed directly back to the fluid supply ready for re-use.

In an alternative embodiment, the fluid system may also include a 'holding tank' or other intermediate container capable of containing fluid, the return conduit configured to direct fluid from the supply conduit to the fluid supply via said holding tank. The preceding embodiment, having the return conduit connected directly to the fluid supply, minimises space requirements and expense and is therefore particularly suited for mobile applications. However, in household, industrial or commercial applications which have large distances between the outlet and fluid supply, the expense of extensive plumbing may be minimised by incorporating a holding tank which can then pass fluid back to the fluid supply via the existing 'mains' lines, or alternatively to the hot water tank or an outlet.

The^" holding tank is also useful in minimising plumbing where the fluid system includes multiple outlets, e.g. the smaller holding tank can be located relatively 'close' to the outlets and each outlet may have a corresponding return conduit connected to the holding tank which may have a single return conduit connected to the fluid supply.

Alternatively, some other preferred embodiments the return conduit may include a main-return-conduit (main conduit) with a number of branched-return-conduits (branched conduits) connected to the main conduit, said main conduit being connected to the fluid supply.

The return and supply conduits may generally be in the form of pipes through which water can be conveyed.

The term 'proximate' as used herein with respect to the outlet and return valve refers to their relative spatial position being substantially close to one another as will be understood by one skilled in the art.

In some preferred embodiments the return valve may be located substantially adjacent the outlet i.e. the return valve and outlet are as close to each other as is practical.

In some further preferred embodiments the return valve may also effectively function . as the outlet i.e. the return valve is 'integrated' with the outlet.

By positioning the return valve proximate the outlet this minimises or eliminates the cold slug of water present in conventional hot water systems.

In relation to the following description of the return valve, it will be understood by those skilled in the art, that there may be more than one return valve. However, the arrangement of said valves will achieve substantially the same objective as that achieved in relation to the following description, given for a single 'three-way' valve, for ease of reference.

Preferably, the return valve is a 'three-way' valve having one inlet connected to said supply conduit, and two outlets, a first valve outlet connected to the fluid system outlet and a second valve outlet connected to the return conduit, wherein said three-way valve is capable of selectively blocking each one of the valve outlets and opening the other.

In an alternative embodiment, the return valve may be formed from two valves, a first valve capable of selectively blocking fluid flow from the supply conduit to the return conduit and a second valve capable of selectively blocking fluid flow from the supply conduit to the outlet.

Preferably, the return valve is capable of being manually actuated to the dispensing and/or recirculation configurations. It may prove useful in many applications to provide such a manual override to allow a user to control the direction of water, e.g. in the case of faults in the controller.

Preferably, the return valve includes at least one solenoid valve. As will be appreciated by one skilled in the art, a solenoid valve may be convenient in applications where the valve cannot be opened or closed manually and/or requires automatic actuation.

Preferably, the solenoid valve is biased towards a first (e.g. dispensing) position directing fluid flow to the outlet and when electricity is provided to the solenoid the valve will move to a second (e.g. recirculation) position directing fluid flow to the return conduit. In an alternative embodiment the solenoid valve may be unbiased and capable of actuating between the first and second positions by reversing the polarity of the electricity supplied to said solenoid. It should be appreciated that many numerous valve configurations are possible for use with the present invention and reference herein to use of a solenoid valve being actuated between two positions , should not be seen to be limiting.

In one embodiment, the return valve may be reversibly actuable between an open configuration, for permitting passage of fluid from the supply conduit to either the outlet, (dispensing configuration) or the fluid supply via the return conduit, (recirculation configuration) and a closed configuration preventing the passage of fluid to both the return conduit and the outlet. 78

Preferably, the controller includes a timer and is configured to actuate the return valve to one of: the open or closed positions, recirculation or dispensing configuration after predetermined time period after activation of the controller.

Preferably, the controller is configured to close the return valve after a preset period of time. Such a timed 'shut-off' provides a useful safety mechanism for ensuring the return valve is closed when there is a fault in the system, e.g. if the hot water tank is faulty and is not heating sufficiently, the cold water may be continuously cycled into the return conduit, thereby potentially wasting energy pumping the water. A user may also turn on the outlet and then leave the vicinity while waiting for the water. There is thus the potential for the user to forget and leave the outlet open, potentially draining the hot water tank if the return valve is not closed.

Preferably, the fluid system includes a pump or the like in fluid communication with the return conduit and fluid supply, said pump capable of pumping fluid from the return conduit to said fluid supply. The provision of such a pump can be useful in applications where there is insufficient fluid pressure to drive fluid through the return conduit to the fluid supply, e.g. where the fluid supply includes a high-pressure mains line the mains pressure may prevent fluid entering from the return conduit.

In one embodiment, the controller is configured to actuate the return valve between the recirculation and dispensing configurations after a predetermined period of time.

Preferably, the predetermined time is the time period required for the volume of water contained in the supply conduit to pass to the return conduit. Thus, this 'time- dependant' embodiment may ensure that only fluid from the fluid supply is passed to the outlet and not the fluid temporarily contained in the supply conduit, i.e. the 'slug'. It will be appreciated that numerous mechanisms may be employed to perform the time- dependant switching including: electronic/mechanical timers, flow-meter revolution counters, or the like.

In another alternative embodiment, the controller is configured to actuate the return valve between the recirculation and dispensing configurations after passage of a predetermined volume of fluid. For example, a flow-meter connected to the return valve may measure the volume of fluid that flows to the return conduit and actuate the return valve to switch to passing fluid to the outlet when a predetermined volume has passed. NZ2008/000078

According to another aspect of the present invention there is provided a method of directing fluid from a fluid supply using a fluid system substantially as hereinbefore described.

According to yet another aspect of the present invention there is provided a method of directing fluid from a fluid supply in a fluid system including an outlet connected to the fluid supply via a supply conduit and a return conduit located proximate the outlet and connected to the supply conduit, said return conduit connected to said fluid supply, said method including the steps of:

- directing fluid from said fluid supply to the return conduit until the temperature of said fluid in said supply conduit reaches a predetermined threshold temperature; and

- directing fluid to said outlet when said fluid in said supply conduit reaches said threshold temperature.

It should be appreciated that while the present invention has been described for a single outlet this should not be seen to be limiting as the present invention may modified for use with multiple outlets.

An example of the present invention used with multiple outlets may include a return valve and temperature sensor at each outlet and a flow switch in a supply conduit connected to each outlet. The controller may be connected to each return valve, temperature sensor and flow switch and being capable of controlling each return valve thereby controlling the entire system on opening of any one of the outlets.

It will be appreciated that where there are multiple supply conduits a flow switch may be required for each said supply conduit.

Preferred embodiments of the present invention can thus provide significant advantages over the prior art including providing a fluid system that may be capable of one or more of:

- reducing the volume of the .'slug' of fluid present in the supply conduit that is passed to the outlet;

- reducing water wastage; minimising power consumption;

minimising manufacturing complexity and cost, and/or

minimising space requirements.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects and advantages of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 shows a schematic diagram of a fluid system according to a first preferred embodiment of the present invention;

Figure 2 shows three schematic diagrams of the fluid system shown in figure 1 in:

Figure 2a a closed configuration

Figure 2b a recirculation configuration; and

Figure 2c a dispensing configuration;

Figure 3 shows a schematic diagram of a fluid system according to a second preferred embodiment of the present invention;

Figure 4 shows three schematic diagrams of the fluid system shown in figure 1 in:

Figure 4a a closed configuration;

Figure 4b a recirculation configuration; and

Figure 4c a dispensing configuration;

BEST MODES FOR CARRYING OUT THE INVENTION

In relation to all the drawings, water flow in each figure is indicated by arrows on the various water conduits (4, 6 and 11) and common reference numerals have been used to indicate the common elements. Figures 1-4 show schematic diagrams of fluid systems according to two alternative preferred embodiments of the present invention. It should be appreciated that the different features of each embodiment are interchangeable without departing from the scope of the present invention.

It will be appreciated that the dimensions, scale and components shown are representative only and may be varied without departing from the scope of the present invention.

It should also be appreciated that, for ease of reference only, the figures are shown with the water system componentry as separate parts in various positions although individual components may be combined or form part of a single apparatus or may be positioned differently without departing from the scope of the present invention.

With respect to figures 1 and 2 there is provided a fluid system according to a first preferred embodiment in the form of hot water system (1). The hot water system (1) has a fluid supply in the form of hot water tank (2), and an outlet control device in the form of tap (3) connected to the water tank (2) via a supply conduit in the form of a first 'supply' pipe (4).

The hot water tank (2) has a heating element (5) for heating the water therein.

A return conduit is provided in the form of second 'return' pipe (6) which connects the supply pipe (4) to the tank (2).

A return valve (7) is provided as a three-way solenoid valve with an inlet port (8) and two outlet ports (9, 10) for respectively passing water from the supply pipe (4) to either the .tap (3), in a dispensing configuration (as shown in figure 2c), or the return pipe (6), . in a recirculation configuration as shown in figure 2b.

Figure 1 shows a closed hot water system (1) without a mains supply line (11) such as is shown in Figure 3. A 'mains' supply (11) is typically not available in many applications such as mobile homes, caravans, yachts, other vehicles, or applications relying on rainwater or other supplies stored in tanks.

The hot water system (1) has a pump (12) in the return pipe (6) for pumping water to the hot water tank (2). The pump (12) is useful in applications where there is insufficient hot water pressure to force a cold water slug along return pipe (6) to the hot water supply (2).

The pump (12) is also useful in forcing water from the return pipe (6) to the mains supply (11) when the water pressure in the mains (11) is higher than that in the return pipe (6). This pressure differential would otherwise stop entry of water from the return pipe (6) to the mains (11).

It will also be appreciated that in applications with a high-pressure mains supply (11) a separate 'holding tank' (not shown) may be provided for holding the water from the return conduit (6) before passing to the hot water tank (2) or mains supply (11).

The hot water system (1) is automatically controlled by an electronic controller (13) which is capable of selectively actuating the return valve (7) between recirculating (shown in figure 2b) and dispensing configurations (shown in figure 2c). The controller (13) is also configured to actuate the pump (12) when the return valve (7) is in the recirculation configuration.

The controller (13) is configured to receive signals from a temperature sensor (14) to determine whether to actuate the return valve (7) to the:

- recirculation configuration when the water temperature is below a preset threshold; or

- dispensing configuration when the water temperature is above the preset threshold.

The temperature sensor (14) comprises a thermistor (not shown) in thermal contact with the water in supply pipe (4) adjacent the return valve (7). The thermistor forms part of an electrical circuit of the controller (13) and reverses the voltage polarity over the return valve solenoid (not shown) when the water temperature passes the preset threshold temperature to thus actuate the return valve (8) between the recirculation and dispensing configurations when the water temperature is respectively below or above the threshold..

A flow switch (15) is provided for detecting flow in the supply pipe (4) when the tap (3) is opened. The flow switch (15) can take any known form of switch capable of closing an electrical circuit upon flow of water in the supply pipe (4), e.g. the flow switch (15) may comprise a pivoting conductive arm with one end in contact with the water in supply pipe (4) such that the arm pivots to close the circuit when there is sufficient flow. An alternative configuration may use a pressure switch or the like.

The return valve (7) is normally initially set in the dispensing configuration (shown in figures 2a, c) when the tap (3) is closed so that as soon as the tap (3) is opened, water will flow in pipe (4) and close the flow switch (15).

In turn, the controller circuit will close and the controller (13) will be activated as electrical power from power supply (16) is supplied to the controller (13). Once activated, the controller (13) will actuate the return valve (7) to the recirculating or dispensing configurations depending on whether the temperature sensor (14) respectively indicates the water temperature is below or above the threshold temperature.

The controller (13) thus only uses power when water flows in the supply pipe (4) (e.g. when opening the tap (3)) and thereby minimise power consumption.

The operation of the hot water system (1) shown in figures 1 and 2 will now be described with respect to figures 2a-c.

Figure 2a shows the system (1) in a closed configuration with the tap (3) turned Off (outlet valve closed) and the return valve (7) in the dispensing configuration. Water flow through the return valve (7) is prevented by the closed tap (3).

When the tap (3) is opened (as shown in Figure 2b) the flow switch (15) detects water flow in supply pipe (4) and the controller (13) is activated.

The controller (13) then applies a voltage across the solenoid of the return valve (7) to actuate between the recirculating or dispensing configurations depending on the water temperature at the return valve (7) as indicated by the temperature sensor (14).

Figure 2b shows cold water in the supply pipe (4) which is detected by the temperature sensor (14) and triggers the controller (13) to actuate the return valve (7) to the recirculating configuration to purge the cold water through the second pipe (6) via the pump (12) to the hot water supply (2).

After the cold water slug has been purged the hot water flowing from the tank (2) along the supply pipe (4) return valve (7) will reach the temperature sensor (14). This hot water is detected by the temperature sensor (14) which triggers the controller (13) to actuate the return valve (7) to the dispensing configuration.

When the tap (3) is closed and water ceases to flow in supply pipe (4) the flow switch (15) opens the controller circuit and cuts power to the controller (13), pump (12) and, return valve (7). The return valve (7) is biased to the dispensing configuration so that when water flow stops, the return valve (7) 'resets' to the initial position as shown in figure 2a.

Although in the figures shown all components share a common power supply, it should be appreciated that in some applications the return valve (7) and/or pump (12) may have separate power supplies to the controller (13).

The controller (13) is capable of rapid actuation of the return valve (7) between the recirculating and dispensing configurations so that in spite of the return valve (7) normally being in the dispensing configuration when the tap (3) is opened, if cold water is detected the return valve (7) will immediately switch to the recirculating configuration. Thus, little, or no cold water is passed to the tap (3).

Figures 3 and 4 show a second preferred embodiment of the present invention which achieves the same result as the embodiment shown in figures 1 and 2 with a different configuration. For ease of reference, like parts have been numbered with like reference numerals.

The hot water system (100) of figures 3 and 4 differs to the first embodiment in the:

- addition of a 'mains' cold water supply (11) connected to the hot water tank (2), and

- replacement of the single three-way return valve (7) of the first embodiment with first (7a) and second (7b) solenoid valves.

The operation of the hot water system (100) shown in figures 3 and 4 will now be described with respect to figures 4a-c.

The first valve (7a) is located in the supply pipe (4) between the tap (3) and the return pipe (6) and selectively blocks water flow to the tap (3). The second valve (7b) is located in the return pipe (6) between the pump (12) and supply pipe (4). It should be appreciated that in some applications it may be suitable to have the pump (12) and second valve (7b) formed as a combined device, e.g. the pump (12) may be configured to only pass water when turned on, thereby also effectively acting as the second valve (7b).

Figure 4a shows the hot water system (100) in a closed configuration with the tap (3) turned Off (outlet valve closed), the first valve (7a) open and the second valve (7b) closed. Water flow through the first valve (7a) is prevented by the closed tap (3).

When the tap (3) is opened (as shown in Figure 4b) the flow switch (15) detects water flow in supply pipe (4) and the controller (13) is activated. The controller (13) applies a voltage across the solenoids in the first (7a) and second (7b) valves to actuate between the recirculating (figure 4b) or dispensing (figure 4c) configurations depending on the water temperature at the temperature sensor (14) in the supply pipe (4) immediately upstream of the first valve (7a).

Figure 2b shows 'cold' water in the supply pipe (4) which is detected by the temperature sensor (14) and triggers the controller (13) to actuate the first valve (7a) to the closed position and the second valve (7b) to the open position to provide the recirculating configuration to purge the cold water through the second pipe (6) via the pump (12) to the mains water supply (11).

Figure 4c shows the hot water flowing in the supply pipe (4) from tank (2) once the cold water slug has been purged, i.e. passed to the return conduit (6). This hot water is detected by the temperature sensor (14) which triggers the controller (13) to actuate the first valve (7a) to the open position and the second valve (7b) to the closed position to provide the dispensing configuration.

The controller (13) comprises circuitry that is configured to selectively and automatically open or close the first (7a) and second (7b) valves (as described above) when the temperature sensor (14) indicates the water temperature passes a preset threshold, i.e. between hot and cold and vice-versa.

When the tap (3) is closed and water ceases to flow in supply pipe (4) the flow switch (15) opens the controller circuit and cuts power to the controller (13), pump (12) and valves (7a, b). The first valve (7a) is biased open and the second valve (7b) is biased closed so that when water flow stops in supply pipe (4) the hot water system (100) 'resets' to the initial position as shown in figure 4a.

In both the first (figures 1 and 2) and the second (figures 3 and 4) embodiments the cold water 'slug' contained in the supply pipe (4) when the hot water system (1 , 100) is in a closed configuration (as shown in Figures 2a and 4a) may be re-circulated by passing the 'slug' back to the tank (2) (as shown in Figures 2b and 4b) when a user opens the tap (3). When hot water from the tank (2) reaches the valve (7, or 7a) the return valve (7, or 7a and 7b) switches to pass the hot water to the tap (3) (as shown in Figures 2c and 4c). This ensures that only substantially heated water may exit the tap (3) when opened.

It should be appreciated that while the figures show components spaced from each other for clarity, in practice it is beneficial to minimise such spacing, particularly between the valves (7 in figures 1 and 2, 7a in figures 3 and 4) and, the outlet tap (4) and/or temperature sensor (14).

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the appended claims.

Claims

CLAIMS:

1. A fluid system including:

- a fluid supply,

- a supply conduit connecting the fluid supply to said outlet;

- a return conduit connected to said fluid supply;

o a dispensing configuration, permitting fluid passage from the supply conduit to the outlet and blocking fluid passage to the return conduit; and

- a controller capable of controlling said return valve to control the direction of fluid, said controller coupled to a sensor in the supply conduit or return valve, said sensor capable of detecting a parameter of interest in the fluid within said supply conduit or return valve; and

- a flow switch coupled to the supply conduit and/or return valve; and

2. A fluid system as claimed in claim 1, wherein the return valve is configured to move to the dispensing configuration when the outlet control device is closed.

3. A fluid system as claimed in claim 1 or claim 2, wherein the controller is configured to reset the flow switch to open the circuit to cut power to said controller when said return valve moves from said recirculation configuration to said dispensing configuration.

4. A fluid system as claimed in any one of claims 1-3, wherein said parameter of interest is selected from one or more of: pressure; flow-rate; density; composition; chemical/mineral content; radioactivity.

5. A fluid system as claimed in any one of claims 1-3, wherein said parameter of interest is the fluid temperature and said parameter value is a predetermined threshold temperature.

6. A fluid system as claimed in claim 5, further including at least one temperature sensor in thermal contact with the fluid in said supply conduit and/or return valve for detecting fluid temperature therein.

7. A fluid system as claimed in claim 6, wherein the temperature sensor is configured to pass a temperature-dependant signal to a display.

8. A fluid system as claimed in any one of claims 6-7, wherein the return valve is configured to move between said recirculation and dispensing configurations upon receiving a temperature-dependant signal from said temperature sensor.

9. A fluid system as claimed in claim 8, wherein the controller is configured to actuate the return valve to:

- the recirculation configuration when said fluid temperature is below said threshold temperature;

• the dispensing configuration when said fluid temperature is equal to or greater than said threshold temperature.

10. A fluid system as claimed in claim 9; wherein the controller is capable of being programmed by the user to vary said threshold temperature

11. A fluid system as claimed in any one of claims 6-10, wherein the controller is configured such that upon receiving a signal from said flow switch indicating fluid- flow and a signal from said temperature sensor indicating the fluid temperature, the controller actuates said return valve to:

- the recirculation configuration when said fluid temperature is below the threshold temperature;

- the dispensing configuration when said fluid temperature is equal to or greater than said threshold temperature.

12. A fluid system as claimed in any one of the preceding claims, wherein the fluid supply includes a hot water tank and a cold water supply conduit to the hot water tank.

13. A fluid system as claimed in any one of the preceding claims, wherein the fluid supply includes a 'mains' hot water supply conduit together with a heater element which is not immediately adjacent to a hot fluid outlet.

14. A fluid system as claimed in any one of the preceding claims, wherein the return valve is connected directly to the fluid supply.

15. A fluid system as claimed in any one of the preceding claims, wherein the return valve is integrated with said outlet.

16. A fluid system as claimed in any one of the preceding claims, wherein the return valve is a 'three-way' valve having one inlet connected to said supply conduit, and two outlets, a first valve outlet connected to the fluid system outlet and a second valve outlet connected to the return conduit, wherein said three-way valve is capable of selectively blocking each valve outlet and opening the other.

17. A fluid system as claimed in claim 16, wherein said return valve is also capable of selectively blocking both outlets.

18. A fluid system as claimed in any one claims 1-15, wherein the return valve includes two valves, a first valve capable of selectively blocking fluid passage from the supply conduit to the return conduit and a second valve capable of selectively blocking fluid passage from the supply conduit to the outlet.

19. A fluid system as claimed in any one of claims 16-18, wherein said return valve is capable of being manually actuated to the dispensing configuration.

20. A fluid system as claimed in any one of claims 16-19, wherein said return valve is capable of being manually actuated to the recirculation configuration.

21. A fluid system as claimed in any one of the preceding claims, wherein the return valve includes at least one solenoid valve.

22. A fluid system as claimed in claim 21 , wherein said solenoid valve is biased towards a first position directing fluid flow to the fluid system outlet, and configured such that when electricity is provided to the solenoid, said valve moves to a second position directing fluid flow to the return conduit.

23. A fluid system as claimed in claim 21, wherein the solenoid valve is capable of actuating between a first position, directing fluid flow to the outlet, and a second position, directing fluid flow to the return conduit, said valve actuable between said .first and second positions by reversing the polarity of electricity supplied to said . solenoid.

24. A fluid system as claimed in any one of the preceding claims, wherein the return valve is reversibly actuable between:

an open configuration, permitting passage of fluid from the supply conduit to either the outlet or the fluid supply via the return conduit, and

- a closed, configuration preventing the passage of fluid to both the return conduit and the outlet.

25. A fluid system as claimed in claim 24, wherein the controller is configured to actuate the return valve between said open and closed configurations after a predetermined period of time after activation of said controller.

26. A fluid system as claimed in claim 1 , wherein the controller is configured to actuate the return valve between said recirculation and dispensing configurations after a predetermined period of time.

27. A fluid system as claimed in claim 26, wherein said predetermined time is the time period required for the volume of fluid contained in the supply conduit to pass to the return conduit.

28. A fluid system as claimed in claim 1 , wherein the controller is configured to actuate the return valve between the recirculation and dispensing configurations after passage of a predetermined volume of fluid.

29. A fluid system as claimed in claim 28, further including a flow-meter capable of generating a signal indicative of the volume-flow past said flow-meter, said controller capable receiving said signal and actuating the return valve between the recirculation and dispensing configurations after passage of a predetermined .volume of fluid.

30. A method of directing fluid from a fluid supply in a fluid system as claimed in any one of the preceding claims.

31. A fluid system, substantially as hereinbefore described, with reference to and as shown in figures 1 and 2.

32. A fluid system, substantially as hereinbefore described, with reference to and as shown in figures 3 and 4.

33. A method of directing fluid, substantially as hereinbefore described with reference to the accompanying figures.