GB2572232A

GB2572232A - A fluid flow regulator for an electric shower

Info

Publication number: GB2572232A
Application number: GB1816358.4A
Authority: GB
Inventors: Mcgowan Luke
Original assignee: Bristan Group Ltd
Current assignee: Bristan Group Ltd
Priority date: 2018-03-21
Filing date: 2018-10-08
Publication date: 2019-09-25
Anticipated expiration: 2038-10-08
Also published as: GB2572232B; GB201816358D0; GB201804518D0; GB2572174A; GB2572174B

Abstract

A fluid flow regulator provides a controlled flow of cold water to a water heater and comprises a first member 26, and a second member 28 moveable with respect to the first member. A biasing spring 34 biases the first member 26 into a position with respect to the second member 28 in which water flow is maximised. A fluid inlet 20 is arranged to bifurcate and provide a first flow 42 to an outlet 24 and a pressure path 44 for water to provide a counter force on the first member against the bias of the spring 34. The second member 28 is a cylindrical collar, and the first member 26 is a longitudinal valve member. The valve member and the collar are shaped such that upon relative movement the cross sectional area for water flow between the collar and the valve member is varied. Upon reduction of the inlet water pressure, the cross sectional area for water flow is increased and upon increase of the inlet water pressure, the cross sectional area for water flow is decreased. The second member 28 is moved by a rack and pinion mechanism.

Description

A Fluid Flow Regulator for an Electric Shower

The present invention relates to a fluid flow regulator for an electric shower or tap. The invention also relates to an electric shower and a tap or hot water outlet device. The invention in embodiments also relates to a method of controlling the output of a hot water outlet device such as an electric shower.

Electric hot water on demand sources, such as provided as or as part of electric showers are well known and typically operate by receiving as an input, a flow of cold water and then heating the water in real time such that the water that leaves the shower is at an appropriate temperature as set by a user. The description below will relate mostly to electric showers, but it will be appreciated that it applies as appropriate to electric hot water on demand water sources. A problem which such showers tend to suffer from is that given that they rely upon instantaneous water heaters, any variation in inlet water pressure can produce a corresponding change in the rate of flow of water through the heater and consequently a change in the temperature of the water that is output from the shower. This can lead to quite significant fluctuations in the temperature of the water from the shower which at the very least can be uncomfortable for a user and in some cases can cause burning.

For example, if a user has set the water temperature at a certain level and this is based on feeling the water coming out of the shower when it is first switched on, the heater will be controlled such as to generate a certain amount of heat required to ensure that the cold water that passes through the shower, when leaving is at a desired temperature or within a certain range of the desired temperature. If the water flow rate reduces then the heater which is still being powered by the same amount of electricity, will have less water to heat which in turn will mean that the water will be heated to a temperature higher than that desired by the user.

GB-A-2,049,884 discloses a fluid flow regulator including a substantially straight tubular body whose ends are arranged to be connected to co-operating inlet and outlet pipes, and which incorporates a partition separating the interior of the housing into an inlet and an outlet compartment. The partition is provided with an opening which interconnects the compartments and is arranged so that the axis of the opening extends generally transverse to the body axis. A control member is supported coaxially with respect to the opening and an elastically deformable ring is provided around the control member. The arrangement is such that the ring tends to deform due to the difference in pressures of the fluid in the inlet and outlet compartments. This results in a change in cross-section of the flow path or paths through the opening in the sense which tends to maintain the rate of flow of fluid through the regulator approximately at a set value. Means for manually adjusting the position of the control member along the axis of the opening are provided such that the set rate of flow can be varied. Although such system can work, a problem arises in that when a user wants to change the temperature of the water coming out of the shower, there can be a significant delay due to the reaction time of the elastically deformable ring. Furthermore, fluctuation in cold water pressure will still affect the through flow and therefore the output temperature.

DE2346350 discloses a liquid flow regulator including an inner sliding piston capable of axial motion relative to a sleeve, the axial position of which is preset to give a chosen flow rate. The underside of the piston is subjected to supply pressure from an inlet and a pressure drop occurs across an orifice between an inlet and outlet chamber. Output flow is transmitted between apertures in the sleeve and piston walls. The piston is spring biased axially against the sleeve and operates to balance the static pressure difference across the regulating orifice. In operation a change in flow rate results in a change in pressure drop to produce a compensating effect.

US2015/0198263 discloses a control valve for controlling liquid flow in a heating and/or cooling installation. The control valve comprises a valve housing with an inlet and an outlet, a flow area regulator for regulating a flow area of an entry opening through which the liquid flowing through the control valve from the inlet to the outlet has to pass. The flow regulator comprises at least one valve member that is rotatable between a fully open position that corresponds to a largest possible flow area of the entry opening and a fully closed position that corresponds to the smallest possible flow area of the entry opening, in which the entry opening is essentially closed, a pressure regulating arrangement downstream of the flow area regulator with a pressure chamber upstream of the flow area regulator and downstream of the pressure regulating arrangement. The pressure regulating arrangement is configured for maintaining an essentially constant differential pressure between the pressure in the inlet and the pressure in the pressure chamber.

US5704390 and GB2254569 disclose further examples of pressure and/or flow regulating devices.

According to a first aspect of the present invention, there is provided a fluid flow regulator, to provide a controlled flow of water onwards to a water heater, wherein the fluid flow regulator comprises a first member in the form of a longitudinal valve member, and a second member in the form of a collar moveable with respect to the first member, wherein the second member is shaped such that upon movement of the second member relative to first member an area for water flow through the fluid flow regulator is varied; a biasing spring to bias the first member into a position with respect to the second member in which area for water flow is maximised, wherein the inlet is arranged to direct a flow of water to the outlet for onwards flow to a water heater and to provide a pressure path for water to provide a counter force on the first member against the bias of the spring member; in which the, the valve member and collar are shaped such that upon relative movement the cross sectional area for water flow between the collar and the longitudinal valve member is varied; such that upon reduction of the inlet water pressure, the cross sectional area for water flow is increased, and such that upon increase of the inlet water pressure, the cross sectional area for water flow is reduced. The fluid flow regulator may be used in a system such as an electric shower or a tap/mixer.

A fluid flow regulator for an electric shower or other electric hot water on demand water source, is provided in which first and second members are provided that are arranged to interact in such a way that upon reduction of the inlet water pressure, the cross sectional area for water flow (between the first member which is a cylindrical collar and the second member which is a longitudinal valve member having a shaped end such that upon relative movement with the collar the cross sectional area for water flow between the cylindrical collar and the longitudinal valve member is varied) is reduced. The shaping of the longitudinal valve member and the manner in which it interacts with the first member ensures that a repeatable and reliable variation in flow rate can be achieved. In contrast to known systems, such as that described above with reference to Figure 1A and 1B or indeed GB-A-2,049,884 which rely upon an elastically deformable member, the fluid flow regulator operates by interaction of two rigid members which ensures a more reliable, repeatable and predictable performance.

In one example, the shaped end of the valve member is tapered.

It is preferred that the shaped end of the valve member is tapered such that as it moves out of interaction with a collar of predetermined cross sectional radius, the available area for passage or flow of liquid increases. The gradient of the tapering is preferably controlled to ensure that a selected variation in the cross sectional area can be achieved to achieve a corresponding control in rate of change of flow rate.

In one example, the inner surface of the collar has a varying diameter such that upon relative movement with the collar the cross sectional area for water flow between the cylindrical collar and the longitudinal valve member is varied. In other words instead of the variation in fluid flow path being achieved by tapering of the valve member the “tapering” is effectively provided internally on the collar.

In one example, the first member has a projection against which in use the biasing spring is arranged to act.

In one example, the first member is a solid longitudinal member. In this example, in which second member is a solid longitudinal member, the assembly and structure of the fluid flow regulator is simplified. Preferably the solid longitudinal member is a unitary element. In one example though it operates in use as if it were a unitary element although it may be composed of a base section and separate tapered nose section, which when arranged within the flow regulator function as a unitary object.

In one example, the second member is moveable in an axial direction such as to enable determination of a fixed reference position with respect to which in use the first member can move.

In one example, the second member is a longitudinal collar.

In one example, the collar has a rack provided thereon and in which the regulator further comprises a pinion adjustable by a user to vary the position of the collar. Providing a collar with an integrated rack limits part count for the fluid flow regulator and hereby simplifies assembly.

According to a second aspect of the present invention, there is provided an electric shower, comprising a fluid flow regulator; a temperature control handle for a user to use to set a desired temperature output for water; and a heater to receive water from the a fluid flow regulator and heat it for output from the shower, wherein the fluid flow regulator is a regulator according to the first aspect of the present invention.

According to a third aspect of the present invention, there is provided a method of controlling the temperature of a water outlet, such as the water from an electric shower, the method comprising providing a regulator including a first member, and a second member moveable with respect to the first member, wherein the second member is shaped such that upon movement of the second member relative to first member an area for water flow through the fluid flow regulator is varied; a biasing spring to bias the first member into a position with respect to the second member in which area for water flow is maximised, wherein the inlet is arranged to bifurcate and provide a first flow onwards to the outlet for onwards flow to the water heater and a pressure path to provide a counter force on the first member against the bias of the spring member; in which the second member is a collar such as a cylindrical collar and the first member is a longitudinal valve member, the valve member having a shaped end such that upon relative movement with the collar the cross sectional area for water flow between the collar and the longitudinal valve member is varied, the method comprising: providing an inlet flow of cold water to the fluid flow regulator; with the regulator, controlling the onwards flow rate of water; and providing the water from the regulator to a heater to heat the water.

According to a fourth aspect of the present invention, there is provided a fluid flow regulator for an electric shower, to provide a controlled flow of cold water onwards to a water heater, wherein the fluid flow regulator comprises a first member, and a second member moveable with respect to the first member, wherein the second member is shaped such that upon movement of the second member relative to first member an area for water flow through the fluid flow regulator is varied; a biasing spring to bias the first member into a position with respect to the second member in which area for water flow is maximised, wherein the inlet is arranged to bifurcate and provide a first flow onwards to the outlet for onwards flow to the water heater and a second flow to provide a counter force on the first member against the bias of the spring member, such that upon reduction of the inlet water pressure, the area for water flow is increased; in which the first member is a cylindrical collar and the second member is a solid longitudinal valve member having a tapered end such that upon relative movement with the collar the cross sectional area for water flow is varied.

According to a fifth aspect of the present invention, there is provided a fluid flow regulator having an inlet and an outlet, the fluid flow regulator being arranged to receive water at the inlet and provide a controlled flow of water onwards to a water heater, wherein the fluid flow regulator comprises: a valve member, and a collar, wherein the collar and the valve member are moveable with respect to each other, and are shaped such that upon movement of the collar relative to the valve member an area for water flow through the fluid flow regulator is varied; a biasing spring to bias the valve member into a position with respect to the collar in which the area for water flow is maximised, wherein the inlet is arranged to receive water at an inlet pressure and to direct a flow of water to the outlet for onwards flow to a water heater and to provide a pressure path for water to provide a counter force on the valve member against the bias of the spring member; in which the collar has a pressure chamber at its proximal end and a pressure chamber at its distal, each arranged in use to receive water at the inlet pressure thereby enabling pressure balancing of the inlet pressure with respect to the collar.

According to a further aspect of the present invention, there is provided a fluid flow regulator having an inlet and an outlet, the fluid flow regulator being arranged to receive water at the inlet and provide a controlled flow of water onwards to a water heater, wherein the fluid flow regulator comprises: a valve member, and a collar, wherein the collar and the valve member are moveable with respect to each other, and are shaped such that upon movement of the collar relative to the valve member an area for water flow through the fluid flow regulator is varied; a biasing spring to bias the valve member into a position with respect to the collar, wherein the inlet is arranged to receive water at an inlet pressure and to direct a flow of water to the outlet for onwards flow to a water heater and to provide a pressure path for water to provide a counter force on the valve member against the bias of the spring member; in which the collar has a pressure chamber at its proximal end and a pressure chamber at its distal, each arranged in use to receive water at the inlet pressure.

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which:

Figures 1A and 1B are schematic representations of an example of a known flow control valve for an electric shower;

Figures 2 to 4 show schematic representations of longitudinal cross sections through a flow control valve for an electric shower;

Figures 5A to 5C show examples of varying liquid flow path sizes;

Figure 6A shows a schematic representation of a longitudinal cross section through a second embodiment of a flow control valve for an electric shower;

Figure 6B shows a perspective view of a partial cutaway of the flow control valve of Figure 6A; and

Figure 6C shows a perspective view of a part of a section through the regulator of Figure 6A.

Referring first to Figure 1, as indicated above, this flow control valve comprises an opening 2 for receiving cold water from a water inlet. The flow valve could be used in an electric shower or indeed in any other temperature controlled water flow system. Typically the opening 2 could be a cold water pipe within a shower housing. An outlet 4 is provided through which water having a known flow rate is exhausted. The water passing out of the outlet 4 of the flow control system will typically pass onwards to a water heater. A control handle 6 is provided which, when rotated, varies the axial position of central arrangement 8. The arrangement 8 includes a cylindrical axial member 10 surrounded by generally frustoconical member 12 arranged to pass axially through a sealing ring 14. A number of grooves 16 are provided in frustoconical member 12. The grooves 16 vary in depth along the axial length of the assembly 8. As the axial arrangement 8 is inserted further into opening defined by the sealing ring 14, the available passage for water is reduced, thus providing flow control.

Regulation can be achieved in that when pressure of water entering inlet 2 increases, this causes a compression of sealing ring 14, which in turn reduces the crosssectional area for the passage of water. Thus what would otherwise result in an increased flow rate, (the increase in pressure delta between inlet 2 and outlet 4), is counteracted by the reduced available cross-section for flow.

As described above, problems that such a system encounters relate to the delay in the movement of the O ring 14 as it interacts with the axial grooves 16.

Figure 2A is a schematic view of a cross section through a fluid flow regulator for an electric shower. The regulator 18 comprises an inlet 20 for connection to a cold water inlet. An outlet 22 is provided through which cold water is exhausted for onward transmission via conduit 24 to a water heater.

The fluid flow regulator comprises a first member 26 and a second member 28 mounted movably with respect to each other such that, in this example, the first and second members 26 and 28 are able to move in a relative axial direction. The first member can be considered to be a longitudinal valve member since its position with respect to the opening of the second member serves to determine the dimension of the opening between the two. Indeed, the effect of such movement is to vary the cross sectional area for water flow. An area 30 is defined between the longitudinal distal end of the first member 26 and the inner cylindrical surface 32 of second member 28.

Figure 2B is an enlarged view of the second member 28 and the longitudinal distal end of the first member 26. As can be seen, in the enlarged view, the first member 26 is shaped such that upon relative movement, the cross sectional area through which, in use, water will flow, varies. Thus, in the view shown in Figure 2B, the cross sectional area which will have a generally cylindrical form, is at a maximum due to the generally chamfered end profile of first member 26.

The longitudinal valve member 26 is preferably a unitary element of solid structure. This is preferable as it is durable and easy to manufacture. Preferably it is formed of a material such as a plastic and can be moulded. In one example it is formed of metal. The avoidance of opening means that there is reduced surface area of the longitudinal valve member which means that there is less surface area for the build-up of residue and/or dirt which can be problematic, particularly if it becomes dislodged and then has the potential to cause a blockage downstream, i.e. in the opening between the first and second members.. In one example the longitudinal valve member is in fact formed of 2 pieces rather than being unitary in structure.

Of course, once arranged within a fluid flow regulator it functions as a single unit, but the provision of a two part valve member provides flexibility in terms of operation of the system as a whole. As explained above, the rate of flow of water through the system is varied by movement of the first and second members with respect to each other. This in turn can be determined by the profile of the tapering of the first member. If a quick change in flow rate (or rather a high responsiveness to relative movement of the first and second members) is needed then a steeper tapering can be used. Conversely if a slow change of flow rate is desired then a more gradual or less steep tapering can be used. By providing the first member 26 as a two part unit, the desired tapering can be provided whilst use is made of a common base.

Referring again to Figure 2A, a spring 34 is provided, which, in this case, is a helical spring and it is arranged to bias the first member 26 in a direction generally away from the second member 28. In Figure 2A, this would mean that the first member 26 was biased to the left. This is achieved by provision of a shoulder 36 upon which the left hand end of spring 34 applies pressure.

The inlet 20 through which cold water enters is generally defined by a cylindrical opening 38 and has at its axial end 40 a central opening for onward transmission of received water.

The opening 40 leads to a bifurcated path such that water can travel in a first direction 42 and also in a second direction 44. Water travelling in the first direction 42 will travel towards the opening 30 defined between the first member and the second member 26 and 28. However, water travelling in the second direction 44 in an axially opposite direction to the propagation of water in direction 42, travels on what may be referred to as a pressure path for the water, to a rear pressure zone 46 provided on the left hand side of the first member 26. As demonstrated by the arrow D water in pressure zone 46 provides a support pressure to the first member 26 which acts against the biasing force of helical spring 34.

In the example shown, the fluid flow regulator housing has a first section 48 and a second section 50. The pressure zone 46 is defined generally by the open end of first section 48 together with a plug 52.

A sealing O ring 54 is provided to ensure a seal between the plug 52 and housing 48.

An inner cylindrical collar 56 is provided presenting an annular end surface 58 for engagement with the shoulder 36.

Second member 28 has on one side thereof a rack 58 integrally formed. A pinion 60 is provided which enables a user to cause axial movement of the second member 28 and thereby to vary the opening between first member 26 and second member 28. A sealing ring 62 is provided to ensure a seal between second member 28 and the housing element 64.

In use a user turns on the water flow which enables water to initially flow in through opening 20 and onwards to outlet 24. By rotation of a handle or control (not shown) which interacts with pinion 60, the relative position of second member 28 is set with respect to first member 26. Thus, the temperature of the outlet water from the shower will be determined by the flow rate of the water. Use of a rack and pinion is a preferred way of providing user control of the position of the second member. In an alternative other means for providing control of the position of the second member may be used. Examples include the use of a multi-geared interaction or use of a control motor such as a stepper motor to accurately provide positional control to a user.

Once the relative position has been set in this way, if the flow rate of water entering inlet 20 decreases due to a reduction in supply pressure, then the pressure in pressure chamber 46 will correspondingly decrease causing first member 26 to move leftwards and thereby increase the size of opening 30 and correspondingly increase, or maintain, the flow rate of water through the fluid flow regulator. Conversely, if the pressure of the water increases, then the pressure within chamber 46 will increase and cause the first member 26 to move rightwards with respect to second member 28, thereby reducing the size of opening 30. Thus, water flow will be reduced, or maintained, as compared to what it would be if no movement of first member with respect to second member took place.

A pressure cut-off switch (not shown) is provided in communication with a pressure chamber 33 arranged in use to contain static water which will be at the same pressure as water passing through the flow control valve. The pressure of water in the chamber 33 determines whether or not a pressure cut-off switch (not shown) is activated which can be arranged to turn off the water heater if the pressure of water falls below some threshold level. This could be set at a level at which the flow of water is so low that the heating is likely to cause burning of a user in the shower.

Looking at Figures 3 and 4, the position of first member can be seen to be different with respect to second member 28. In Figure 3, a maximum opening is provided and this is set by a user. Subsequently, the pressure increases and this causes the first member to move to the right as can be seen by the relative position of collar 56 and first member 26. The cross section 30 is thereby reduced and the water flow is maintained at a corresponding level to ensure that there is no variation in temperature from the shower.

In the examples shown the second member 28 is provided as a cylindrical collar of uniform circular cross-section and the variation in cross-section for water flow is achieved by the tapered end of the first member. In another example, the inner surface of the collar has a varying diameter such that upon relative movement with the collar the cross sectional area for water flow between the cylindrical collar and the longitudinal valve member is varied. In this case the cross-section of the first member can be uniform and variation in available cross sectional area for water flow is derived by the variation in the internal diameter of the collar. In this example at the left hand part of the collar the internal diameter is larger than at the right hand side such that longitudinal relative movement of the first member with respect to the second member causes a variation in the cross-section for water flow.

In another example the internal transverse cross section of the second member 28 is not circular, but instead is of some other shape such as square, rectangular, elliptical or indeed any desired shape. The first member will of course need to be shaped to correspond to the shape of the internal cross section of the second member to enable interaction and control of the available cross section for flow of water as a result of relative axial movement.

Figures 5A to 5C are end views looking axially into the second member 28, with the first member 26 in position within the fluid flow regulator. No contours or edges are shown on the first member. As can be seen there is a variation in available crosssectional area for the flow of liquid through the fluid flow regulator between the first and second members 26 and 28. In Figure 5A the available cross-sectional area is close to a minimum. The first member 26 is effectively close to its most right hand position similar to that shown in Figure 2A. Such a relative position of the first and second members might exist when the water pressure is at a maximum and so the cross section for passage of water is reduced to control the flow of water to a desired volumetric flow rate.

In the example of Figure 5C, the water pressure is reduced and so if the available cross section was the same as that shown in Figure 5A, the volumetric flow rate would correspondingly reduce which could in turn lead to an increase in the temperature of the output water which leaves the shower unit as a whole, i.e. after it has been heated by the electric heater. The position of the first and second members shown in Figure 5C corresponds to that of Figure 3. Figure 5B shows an intermediate position.

As described throughout the fluid flow regulator is suitable for use with an electric shower. In other embodiments the regulator is used as a control for a hot water dispenser in the form of a tap or other outlet without necessarily including a shower head coupled or attached thereto. For example the regulator could be provided as part of a hot water on demand tap outlet which is arranged to heat water when turned on in an analogous manner to an electric shower but instead to dispense it via a tap opening.

Figure 6A shows a longitudinal cross section through a second embodiment of a flow control valve for an electric shower.

Figure 6B shows a perspective view of a partial cutaway of the flow control valve of Figure 6A.

The flow control valve of Figures 2 to 5 works well. However, to ensure pressure equalisation and to avoid any risk of inlet pressure itself leading to an increase in flow rate independently of the determined position of the valve, Figure 6A includes a pressure equalisation mechanism 72. In some situations where there is an unexpected increase in the inlet pressure, for example due to a surge in water mains pressure, the effect of the water pressure acting on an end surface 27 of member 28 can be to cause it to move and thereby open more than required the flow path 30 for water between the members 26 and 28.

This can occur in particular when the valve member is already positioned relative to the collar such that the cross section 30 for flow is small, because the pressure is already high. In this situation, it may not be possible for the valve to close more, which will simply mean that if pressure is increased the additional pressure can only act on the surface 100 of the collar. This can cause the collar to move in the same direction (to the right in Figure 2A) as the valve, thereby opening the flow path and leading to much greater and undesirable water flow.

This is addressed by a pressure balancing or equalisation mechanism 72 shown in Figures 6A and 6B. The mechanism 72 includes a generally cylindrical member 74 arranged to move slidably under the control of a pinion 76 in the same way as the member 28 operates shown in Figures 2A to 2C. In this example however, a seal, in the form of a sealing ring 76, is provided at a distal end of the generally cylindrical member 74. The generally cylindrical member 74 has a closed end surface 78 arranged to define a surface of a pressure chamber 80. The pressure chamber 80, in this example is defined by internal surfaces 81 and 83 of the regulator, together with the outer side of end sirface 80.

The generally cylindrical member 74 is provided with an external rack 82 and in addition, includes a number of circumferential openings 84 through which water flows in normal use to an outlet 86 similar to the outlet 24 shown in Figure 2A.

Water enters the flow control valve 70 via an inlet 88. The water flowing into the valve 70 enters a flow path 90 and from here is able to pass between the opening that is defined between the end of the longitudinal member 92 and the generally cylindrical member 74 through which water will flow. In a manner similar to the system described above with reference to Figure 2A, a pressure chamber 94 is defined and arranged to receive a flow of water from the inlet 88 which causes pressure on the member 92 against the force of biasing member (spring) 96.

In normal functioning, the pressure within chamber 94 balances against the force provided by the spring 96 such that given the position at which the cylinder 82 has been set by a user with the rack and pinion mechanism 76, the rate of flow through the cylinder 74 will be at a desired rate such as to ensure that the temperature that ultimately the water is heated to, can be fixed.

However, in the event of an over pressure situation from the inlet water, a pressure channel 98 is provided which facilitates passage of water to pressure chamber 80 so as to impinge on end surface 78 of the cylindrical member 74. Thus, there is a pressure balancing of the position of the generally cylindrical member 74 since the end surface 78 of the generally cylindrical member 74 will also be subject to water at the same defined inlet (over-)pressure. Thus, this will overcome the otherwise excessive pressure appearing at and acting upon the end surface 100 of the cylinder 74 at its inlet end. Seal 85 ensures that there is no leakage between the proximal end of the generally cylindrical member 74 and the inner surface 81 of the regulator.

At the distal end of the generally cylindrical member 74, the water inlet pressure acts on the end surface 78 of the generally cylindrical member 74 and at its proximal end the inlet water pressure acts upon the end surface 100.

Thus, the collar can be thought of as having a pressure chamber at each of its ends, each arranged in use to receive water at the inlet pressure thereby enabling pressure balancing of the inlet pressure with respect to the collar. This ensures that inlet pressure variation, and in particular over-pressure, will not lead to movement of the collar and therefore undesirable change in the cross section of the space between the collar and the valve member.

In addition, a pressure switch 102 is provided which is operable to act as a cut-off to the electrical power supply to a downstream heater in the event that the water pressure in chamber 80 diminishes below some defined threshold.

Figure 6C shows a perspective view of a part of a section through the regulator of Figure 6A. As shown and indicated by arrow 110 water from the inlet reaches the end surface 78 of the generally cylindrical member and pressure chamber 80 defined in part by inner surfaces of the housing of the regulator. A pressure is therefore applied to the generally cylindrical member which will increase if, say, there is a sudden increase in the inlet water pressure. Thus a counter to the force at the inlet of the generally cylindrical member 74 is provided.

The arrangement of the opening 84 within the cylindrical member 74 can be provided as appropriate. In one example, a single row of arcuate openings are provided along a length of the cylinder. In another example, two or more parallel or helically arranged rows of openings are provided so as to ensure that the flow of water through the openings and onto channel 86 is substantially uniform in its radial direction.

Embodiments of the present invention have been described with particular reference to the examples illustrated. However, it will be appreciated that variations and modifications may be made to the examples described within the scope of the present invention.

Claims

1. A fluid flow regulator having an inlet and an outlet, the fluid flow regulator being arranged to receive water at the inlet and provide a controlled flow of water onwards to a water heater, wherein the fluid flow regulator comprises:

a valve member, and a collar, wherein the collar and the valve member are moveable with respect to each other, and are shaped such that upon movement of the collar relative to the valve member an area for water flow through the fluid flow regulator is varied;

a biasing spring to bias the valve member into a position with respect to the collar in which the area for water flow is maximised, wherein the inlet is arranged to receive water at an inlet pressure and to direct a flow of water to the outlet for onwards flow to a water heater and to provide a pressure path for water to provide a counter force on the valve member against the bias of the spring member;

in which the collar has a pressure chamber at its proximal end and a pressure chamber at its distal, each arranged in use to receive water at the inlet pressure thereby enabling pressure balancing of the inlet pressure with respect to the collar.

2. A fluid flow regulator according to claim 1, in which the collar has a closed distal end defining a wall of the pressure chamber at its distal end.

3. A fluid flow regulator according to claim 1 or 2, in which the collar has openings along its axial length to provide an outlet for water flowing therethrough.

4. A fluid flow regulator according to any of claims 1 to 3, in which the collar has a rack formed thereon, for engagement with a control pinion, moveable by a user to determine a position of the collar with respect to the valve member.

5. A fluid flow regulator according to claim 3, in which the opening are formed between teeth of the rack.

6. A method of regulating fluid flow using a fluid flow regulator having an inlet and an outlet, the fluid flow regulator being arranged to receive water at the inlet and provide a controlled flow of water onwards to a water heater, wherein the fluid flow regulator comprises:

in which the collar has a pressure chamber at its proximal end and a pressure chamber at its distal, each arranged in use to receive water at the inlet pressure thereby enabling pressure balancing of the inlet pressure with respect to the collar; the method comprising:

causing water to flow through the regulator.

7. A fluid flow regulator, to provide a controlled flow of water onwards to a water heater, wherein the fluid flow regulator comprises a first member in the form of a longitudinal valve member, and a second member in the form of a collar, the first and second members being moveable with respect to each other, wherein at least one of the first and second members are shaped such that upon movement of the second member relative to first member an area for water flow through the fluid flow regulator is varied;

a biasing spring to bias the first member into a position with respect to the second member in which area for water flow is maximised, wherein the inlet is arranged to direct a flow of water to the outlet for onwards flow to a water heater and to provide a pressure path for water to provide a counter force on the first member against the bias of the spring member;

in which the, the valve member and collar are shaped such that upon relative movement the cross sectional area for water flow between the collar and the longitudinal valve member is varied;

such that upon reduction of the inlet water pressure, the cross sectional area for water flow is increased, and such that upon increase of the inlet water pressure, the cross sectional area for water flow is reduced.

8. A fluid flow regulator according to claim 7, in which the valve member has a tapered end.

9. A fluid flow regulator according to claim 7, in which the inner surface of the collar has a varying diameter such that upon relative movement with the collar the cross sectional area for water flow between the cylindrical collar and the longitudinal valve member is varied.

10. A fluid flow regulator according to any of claims 7 to 9, in which the valve member has a projection against which in use the biasing spring is arranged to act.

11. A fluid flow regulator according to any of claims 7 to 9, in which the valve member is a solid longitudinal member.

12. A fluid flow regulator in which the collar is moveable in an axial direction such as to enable determination of a fixed reference position with respect to which in use the valve member can move.

13. A fluid flow regulator according to claim 12, in which the collar has a rack provided thereon and in which the regulator further comprises a pinion adjustable by a user to vary the position of the collar.

14. A fluid flow regulator according to any of claims 7 to 13, further comprising a manual adjustment control to enable a user to manually control the relative positions of the valve and collar members.

15. A fluid flow regulator according to any of claims 7 to 14, in which the collar has a closed distal end and the inlet of the regulator is arranged to direct water to a pressure chamber defined in part by the closed distal end of the collar.

16. A fluid flow regulator according to any of claims 7 to 15, in which the collar has openings along its length to allow for the flow of water therethrough.

17. An electric shower or a tap or a hot water outlet device, comprising a fluid flow regulator;

a temperature control handle for a user to use to set a desired temperature output for water; and a heater to receive water from the a fluid flow regulator and heat it for output from the shower, wherein the fluid flow regulator is a regulator according to any of claims 7 to 16.

18. A method of controlling the temperature of an electric shower, a tap or a hot water outlet device, the method comprising providing a regulator including a valve member, and a collar moveable with respect to the valve member, wherein the collar is shaped such that upon movement of the collar relative to valve member an area for water flow through the fluid flow regulator is varied;

a biasing spring to bias the valve member into a position with respect to the collar in which area for water flow is maximised, wherein the inlet is arranged to bifurcate and provide a first flow onwards to the outlet for onwards flow to the water heater and a pressure path to provide a counter force on the valve member against the bias of the spring member;

in which the collar and valve member are shaped such that upon relative movement the cross sectional area for water flow between the collar and the valve member is varied, the method comprising:

providing an inlet flow of cold water to the fluid flow regulator; with the regulator, controlling the onwards flow rate of water; providing the water from the regulator to a heater to heat the water.