AU2245200A - Thermostatic valve and tap assembly - Google Patents

Description

Wr P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title e: THERMOSTATIC VALVE AND TAP ASSEMBLY GSA INDUSTRIES (AUST.) PTY LTD Applicant: The following statement is a full description of this invention, including the best method of performing it known to me: 1 Doament THERMOSTATIC VALVE AND TAP ASSEMBLY The present invention relates to a thermostatic valve, and a tap assembly for use with such a valve. The invention has particular application for use with open vented storage water heaters (also known as low pressure water heaters) and it will be convenient to describe the invention in relation to that application.

It should be appreciated however, that the invention could have wider application and is therefore not restricted to the particular application described.

Open vented storage water heaters traditionally have been coupled to hot/cold water mixer taps which provide a permanently open passage to allow S" •:venting of expanding hot water, as well as providing a tap mechanism that enables the user to regulate the volume of water flow and the temperature of 0 that water. Such mixer taps generally have employed two tap valve mechanisms which facilitate the above described water volume and temperature control. Typically, one of the two tap mechanisms controls cold water flow direct to the mixing chamber of the mixer tap, while the other of the tap mechanisms controls cold water flow to the water heater. A schematic illustration of a traditional form of water mixer tap is shown in Figure 1.

In Figure 1, the water mixer tap 10 includes a cold water inlet 11, that communicates with a passage 12 which extends in either direction to two spaced-aport tap valves 13 and 14. Each of the tap valves 13 and 14 includes a valve head 15, 16 for seating against a respective valve seat 17, 18 and flow of water past the respective valve heads 15, 16 is dependent on the size of the gap between the head and the respective seats 17, 18. Flow past the valve head 15 proceeds directly to the mixing chamber 19 of the mixer tap 10, while flow past the valve head 16 proceeds to the water heater, through the passage 20, and after heating that water, returns through the passage 21 to the mixing chamber 19. In the mixing chamber 19, the hot and cold flows mix and exit the mixer tap 10 through the water outlet 22.

The mixer tap 10 advantageously can be used with a water heater without the necessity for an expansion or pressure relief valve. This occurs because the heater is directly connected to the passage 21 which is in permanent communication with the water outlet 22. Thus, the mixer tap eliminates the possibility of pressure build-up within the heater, because any 3 water that expands due to heating, can expand into the passage 21 and through the outlet 22.

Arrangements such as that shown in Figure 1 have several inherent problems. Firstly, by the nature of the mixer tap, the user is required to continuously adjust the relative mix of hot and cold water to maintain a constant outlet temperature because the temperature within the heater tends to drop as its heated water reserves are depleted and replacement cold water is introduced thereinto.

The arrangement is also sensitive to changes in cold water supply pressure, because pressure loss through the heater differs from pressure loss in the flow passage that extends directly to the mixing chamber 19. Thus, any change in cold water supply pressure will cause a change in the relative proportions of hot and cold water entering the mixing chamber 19, so that the temperature through the tap outlet will change.

The arrangement can also be awkward to use, because any desirable change to the water outlet temperature or flow, requires careful regulation of both tap valves.

It is an object of the present invention to provide a mixer tap that o overcomes one or more of the above disadvantages of the prior art. It is a ooo* further object of the invention to provide a thermostatic mixer valve for use in a mixer tap, for use with an open vented storage water heater. It is still a further object of the invention that a thermostatic mixer valve be provided in a form that can be readily installed and removed from a mixer tap.

According to a first aspect of the present invention there is provided a thermostatic mixer valve, including a valve housing having first and second inlet ports for connection to a supply of cold water and a supply of hot water respectively, said first and second inlet ports being arranged for respective communication with first and second flow passages which communicate with a mixing chamber, said mixer valve further including first and second outlet ports, said first outlet port being in communication with said first flow passage and in use, with water heating means and flow of water from said first passage flow through said first outlet port to said water heating means and from said first flow passage to said mixing chamber is controlled by thermostatic control means, said control means including a movable member which is movable in a first 4 direction to reduce the amount of water which can flow to said first outlet port and increase the amount of water which can flow to said mixing chamber and in a second direction to increase the amount of water which can flow to said first outlet port and decrease the amount of water which can flow to said mixing chamber, said thermostatic controller reacting to the temperature of mixed water in either said first or second directions upon deviation of the mixed water temperature from a preset temperature, said second inlet port being in use, in communication with said water heating means to receive heated water therefrom and for flow through said second flow passage into said mixing chamber, said second outlet port being in communication with said mixing chamber for dispensing mixed water therefrom.

:The thermostatic controller can be set to position the movable member so that the mixed water in the mixing chamber has any desirable temperature and movement of the movable member by the controller occurs when the S 15 temperature of the water in the mixing chamber deviates from the set •.temperature of the controller. The level of deviation required to cause the movable member to be moved, may vary depending on the sensitivity of the thermostatic controller. However, it is not considered necessary that the controller be particularly sensitive. Preferably the movable member is a piston or pistons and preferably at least a portion of the first flow passage is defined by one or more of the pistons.

Movement of the movable member alters the amount of unheated water which flows from the first flow passage through the first outlet port to the heating means. Thus, when the thermostatic controller is exposed to mixed water which exceeds the preset temperature, the movable member is moved in the first direction to a position in which it restricts the flow of unheated water through the first outlet port. By this action, a greater proportion of unheated water remains within the first flow passage and flows directly to the mixing chamber, while reduced proportion of unheated water flows through the first outlet port for heating by the heating means. Thus, the temperature of water in the mixing chamber is reduced.

Conversely, if the thermostatic controller is exposed to water which is lower than the preset temperature, the movable member is moved in the second direction by the controller to have an effect which is the reverse of that described above.

The first flow passage is preferably at least partly cylindrical and the movable member is preferably a cylindrical piston which is disposed within the at least partly cylindrical portion of the first flow passage. Communication between the first flow passage and the first outlet port is preferably through an opening in the first flow passage and flow through that opening is controlled by the position of the piston relative to that opening. In one embodiment, the piston can close the opening by extending fully thereacross and in the closed condition, the piston may engage a suitably formed seat. The seat could have any suitable configuration and could for example be made of a resilient material, such as a rubber-like material, against which the piston abuts. Alternatively, the piston may simply extend across the opening to provide the required flow S"restriction. In this latter arrangement, the outer diameter of the piston is slightly smaller than the inner diameter of the flow passage, such that in the closed condition, negligible water flow between the piston and the flow passage to the first outlet port occurs. The latter arrangement is advantageous, because the valve can accommodate maximum expansion of the thermostatic element of the controller beyond the normal position of a seat, by allowing continued movement of the piston beyond the position at which the first flow passage opening is closed. Further in this arrangement, a seal may be provided to seal between the flow passage and the piston, to fully seal against or close flow of water to the first outlet port. An O-ring seal, preferably disposed in the intemrnal wall of the flow passage adjacent the flow passage opening, can be provided for this purpose.

Full closure of water flow to the first outlet port advantageously permits the valve to have cold water only exit through the second outlet port. That is, by fully closing flow of water to the first outlet port, no water flows to the water heater for heating and thus all of the water that flows through the first inlet port flows through the first flow passage and out through the second outlet port, without being mixed with any heated water. Therefore, if it is desirable to receive cold or unheated water only, such as for drinking purposes, totally unheated water can be provided by setting the thermostatic controller to maintain the movable member to close flow through the first outlet port.

I,

6 The valve of the invention advantageously permits the second flow passage to remain permanently in unrestricted communication with the mixing chamber, so that any water expanding from the heating means can leak through the second flow passage, into the mixing chamber and through the second outlet port. It is particularly advantageous that flow through the second flow passage is not restricted by movement of the movable member in either of the first or second directions, because that may hinder venting of expanding heated water. In particular, in a valve in which vented water is required to flow past a movable member of the above kind, failure of the member can prevent venting from occurring.

It is a further advantage of the invention that the backpressure within the heater due to the function of the valve is minimised, because throttling of the water (usually mains water pressure) by the movable member occurs adjacent or near the first inlet port. Thus, the greatest loss of pressure occurs prior to the 15 water flowing to the heater. This arrangement differs from an alternative arrangement in which the movable member is positioned at or adjacent to the second outlet port, causing a build up of pressure at that port and thus within the heater. The heater controlled by the valve of the present invention is thus subject to reduced pressure that results in an increased life and reliability for the o 20 heater.

According to a second aspect of the present invention there is provided a thermostatic mixer valve, including a valve housing having first and second inlet ports for connection to a supply of cold water and a supply of hot water respectively, said first and second inlet ports being arranged for respective communication with first and second flow passages which communicate with a mixing chamber, thermostatic control means is provided for controlling flow of water from said first and second inlet ports to said first and second flow passages, said control means including a movable member which is movable by a thermostatic controller in a first direction to reduce flow of water through said first inlet port and increase flow of water through said second inlet port, and in a reverse, second direction, to increase flow of water through said first inlet port and to decrease flow of water through said second inlet port said thermostatic controller reacting to the temperature of mixed water to move said movable member in either of said first or second directions upon deviation of the mixed water temperature from a preset temperature, said movable member having maximum movement in said first direction to at least substantially close communication between said first inlet port and said first flow passage and having maximum movement in said second direction to substantially close communication between said second inlet port and said second flow passage, said mixer valve further including an outlet port in communication with said mixing chamber for dispensing water therefrom. Preferably the movable member is a piston or pistons, and preferably the, or one of the pistons, includes a flow passage defined therethrough.

Movement of the movable member is controlled by a thermostatic controller, which monitors the mixed temperature of the water and which positions the movable member relative to the first and second inlets to control water flow through those inlets to achieve the appropriate hot and cold water mix for the desired temperature.

The movable member of the mixer valve is arranged to reciprocate between one position in which it at least substantially closes communication between the first inlet and the first flow passage and another position in which it substantially closes communication between the second inlet and the second flow passage. In each of these positions, communication between the inlet and S 20 the flow passage which is not substantially closed by the movable member is at a maximum.

The movable member is arranged to substantially close communication between the second inlet and the second flow passage only and not to completely close that communication, so that leakage of hot water may occur past the movable member as necessary. Thus, the mixer valve of the invention, like the prior art mixer of Figure 1, can accommodate expansion of hot water from the heater, by leakage of the expanding water past the movable member and through to the mixing chamber and the mixer outlet.

Valves according to the invention can be employed in a tap assemblies.

A tap which employs a mixer valve according to the first aspect of the invention includes a tap inlet port for connection to a cold water supply, flow of cold water through said tap inlet port being controlled by valve means, said tap inlet port being in communication with said first inlet port of said mixer valve, said mixer tap further including a tap outlet flow passage in communication with said first 8 outlet port and a water heater tap inlet flow passage in communication with said water heater and said second inlet port, and a tap dispensing flow passage in communication with said second outlet port for dispensing water mixed in said mixer valve.

A tap which employs a mixer valve according to the second aspect of the invention includes a tap inlet port for connection to a cold water supply, flow of cold water through said tap inlet port being controlled by valve means, said tap inlet port being in communication with first and second tap flow passages, said first tap flow passage communicating with said first inlet port of said mixer valve while said second tap flow passage communicates in use, with the inlet of a water heater, a third tap flow passage communicates in use, both with the outlet of the water heater for receipt of heated water, and with said second inlet port of •9 ,said mixer valve, water from said first and third tap flow passages being mixed in said mixer valve and said tap including an outlet flow passage for dispensing 15 the mixed water.

The attached drawings show example embodiments of the invention of the foregoing kind. The particularity of those drawings and the associated description does not supersede the generality of the preceding broad description of the invention.

20 Figures 2 and 3 show a mixer valve 30 according to one aspect of the invention. The mixer valve 30 is of generally elongate form and includes an upper portion 31 of a cylindrical valve housing that accommodates a water temperature adjustment spindle 32 in threaded connection therewith at 33. The spindle 32 is of solid cylindrical form and includes an O-ring groove 34 for accommodating an O-ring 35, for sealing the spindle 32 within the inside surface 36 of the upper portion 31 of the valve housing. The upper portion 31 includes a further O-ring groove 37 that accommodates an O-ring 38 on the external surface 39 of the upper portion 31. That O-ring 38 provides for sealing engagement when the mixer valve 30 is fitted within a mixer tap. The outer surface 39 of the upper portion 31 may also include connection means which facilitate connection of the valve 30 within a mixer tap and such connection means may be a threaded connection.

A middle portion 40 of the cylindrical valve housing extends about a piston 41 and the upper end of a thermostatic controller 42. The upper 9 portion 31 and the middle portion 40 are joined, such as by a threaded joint, to form a cartridge that can be installed and removed from a mixer tap as a single unit. The thermostatic controller 42 is of a known form and example controllers can be found in the specifications of US Patent Nos. 3180150 and 4607788.

The thermostatic controller 42 includes an internal plunger, only the end 43 of which is shown in Figures 2 and 3. It can be seen that the plunger end 43 is in contact with the lower end of the spindle 32. That contact may be fixed, such as by a threaded contact, or it may be an abutting contact only. The plunger end 43 is arranged to bear against the underside of the spindle 32 so that movement of the plunger relative to the spindle is prevented.

The plunger is housed within a housing 44 of the controller 42 and relative movement between the plunger and the housing 44 occurs when the temperature of the water flowing through the outlet 45 of the valve 30 changes.

The middle portion 40 of the valve housing includes two inlet ports 46 and 47 and these ports are separated longitudinally by a transverse annular portion 48 that sealingly engages the outer surface 49 of the piston 41 by an Oring 50. The annular portion further includes an O-ring 51 located within a groove 52 that serves to provide sealing engagement between the middle portion 40 of the valve housing and a mixer tap to which the mixer valve 30 is fitted. Further O-rings which are shown in the drawings, but which do not *require description are provided for the same purpose.

The piston 41 includes an annular wall 53, which is coaxial with the .i general longitudinal axis of the valve 30 and is arranged to engage a valve seat 54 disposed on the underneath surface of the upper portion 31 of the valve housing. It is preferred that engagement of the piston with the valve seat 54 completely closes flow between the inlet 46 and a flow passage 55 within the piston 41. To ensure complete closure, a resilient seat 54 may be employed, such as a rubber or rubber-like seat.

The piston 41 further includes a radially inward extending base 56 that extends into fixed connection with the outer surface of the housing 44. The fixed connection between the base 56 and the housing 44 may be achieved in any suitable manner such as by a threaded connection and is such that axial movement of the housing causes equivalent axial movement of the piston 41.

The radially extending base 56 includes a plurality of axial flow passages 57 that facilitate flow of water from the flow passage 55 through to a mixing chamber 58. Thus, water flowing through the inlet 46, flows over the upper edge of the piston 41 when that upper edge is not sealingly engaged with the seat 54, and into the flow passage 55. In the position shown in Figure 1, the upper edge of the piston 41 is spaced from the seat 54 and therefore in this position, flow of water through the inlet port 46 to the flow passage 55 will occur.

From the flow passage 55, the water then flows through the axial flow passages 57 and into the mixing chamber 58. Water which flows into the mixing chamber 58 is mixed therein before flowing out of the mixer valve 30 through the outlet Mixing of water is not wholly restricted to within the mixing chamber 58, but can also take place within the tube 58a.

The inlet 47 communicates with the mixing chamber 58 through a flow passage between an upper internal edge 59 of the middle portion 40 of the 15 valve housing and a lower external edge 60 of the piston 41. In the position :shown in Figure 2, the upper and lower edges 59 and 60 are in close proximity and therefore flow between those edges will be largely restricted. The shape of :"the respective edges 59 and 60 is not important for the invention. What is important is that the flow communication between the inlet 47 and the mixing chamber 58 be substantially closed when required.

The thermostatic controller 42 includes a thermostatic element within its lower end 62, generally including some form of temperature sensitive material, *such as a wax that can expand or contract on increasing or decreasing temperature, and expansion and contraction of that material drives the plunger contained within the housing 44. The thermostatic controller could alternatively take any other suitable form as is known in the art.

The lower end 62 of the controller 42 is exposed to the mixed temperature of water that flows through the outlet 45 from the mixing chamber 58. Thus, any change in the temperature of water in the outlet 45 will cause the thermostatic element to react, either by contraction or expansion of the temperature sensitive material. That change in volume of the temperature sensitive material drives the plunger 43 in the housing 44, causing movement of the housing 44 and resulting in simultaneous movement of the piston 41, either toward or away from the valve seat 54. Movement of the piston 41 in the above 11 described manner respectively decreases or increases the volume of water from the inlet ports 46 and 47 that can flow through the respective flow passages and into the mixing chamber 58. Thus, movement of the piston 41 toward the seat 54 reduces the opening between the inlet port 46 and the flow passage 55 so as to reduce the volume of the water flowing into the flow passage 55 from the inlet port 46. That movement will, in contrast, facilitate increased flow through the inlet 47 as the lower edge 60 of the piston 41 moves away from the upper edge 59 of the middle portion 40. Movement of the piston in the reverse direction, ie away from the valve seat has the opposite effect, in that water flow through the inlets 46 and 47 will be respectively increased and decreased.

The piston 41 sealingly engages the valve seat 54 in the extreme upward stroke thereof. That sealed engagement results from the type of seat and piston edge employed and by the relationship between the thermostatic controller 42 and a spring 63 acting on the controller 42 to which the piston 41 is fixed. The coil spring 63 is positioned in compression between one end 64 of an annular conduit 65 and a bearing ring 66. Expansion of the thermostatic element of the thermostatic controller 42 acts against the coil spring 63, to move the piston 41 away from the valve seat 54. The coil spring 63 locates one end of the thermostatic controller 42 and facilitates reciprocal movement of the **0controller.

While it is not essential to the invention that the inlet port 46 is connected to a cold water supply, that would normally be the case and in such an .i arrangement movement of the piston 41 toward the valve seat 54 would occur when the temperature of the water in the outlet 45, was below that which was required, so as to reduce the amount of cold water entering the mixing chamber 58 and in contrast, to increase the amount of hot water. It follows, that the arrangement of the upper and lower edges 59, 60 would normally control flow of hot water through the inlet 47, so as to substantially restrict that flow when the piston 41 is in the extreme lower position of its stroke. However, the edges 59 and 60 do not enter into a sealed engagement in that position of the piston and thus, the respective edges always facilitate flow of water therepast. The arrangement does however, significantly restrict water flow therepast, so that in 12 practice when the piston 41 is in the lowest position in its stroke, hot water flow into the mixing chamber 58 is relatively negligible.

In practice the piston can be arranged to be manually adjustable past the level in which hot water flow is restricted at the junction of the upper and lower edges 59 and 60, to facilitate increased flow of cold water. That arrangement, is however separate from actuation by the thermostatic controller 42.

The arrangement described above facilitates drainage through the mixer valve of excess water produced by expansion during water heating, to prevent pressure build-up within the heater. The expanded water will simply leak between the piston 41 and the middle portion 40, and if there is sufficient leakage, that water will pass through to the outlet The mixer valve 30 could appropriately be used for a variety of water heater installations, but its primary use is with relatively small unvented water storage heaters. Such heaters may also embody an instantaneous heating 15 capacity. The mixer valve preferably forms part of a tap assembly for such a heater and a suitable assembly is shown schematically in Figure 4.

In Figure 4, a cold water supply is attached to the inlet 67 of the tap assembly which is generally designated by the reference numeral 68. A tap valve 69 is disposed at the internal end of the inlet 67, which governs flow of water through the inlet. The tap valve 69 can be a simple screw valve having a head 70 that can seat in the closed condition of the tap valve, against a valve seat 71. Movement of the head 70 toward and away from the seat 71 is by a .o threaded spindle 72 which is turned in a threaded opening 73 in the tap assembly 68 by a handle 74. The tap valve 69 could clearly take other designs.

It could for example, be of a non-rising stem design, or any other suitable form.

The inlet 67 is connected to a supply of cold or unheated water and water that flows past the valve seat enters a flow passage 75 that splits between two further flow passages 76 and 77. The flow passage 76 extends directly to a mixer valve 78, which may be of the same configuration as that shown in Figures 2 and 3. The flow passage 77 extends in communication with the inlet of a water heater, such as an open vented water storage heater described earlier. The tap assembly further includes a flow passage 79 in communication with the outlet of the water heater and that flow passage extends to the mixer valve 78.

13 The flow passages 76 and 79 communicate with separate inlet ports of the mixer valve 78. Water flowing into the mixer valve 78 flows into the mixing chamber thereof and through the outlet thereof, into the outlet 80 of the tap assembly 68. The thermostatic controller of the mixer valve senses the temperature of the mixed water, and adjusts the flow volume through the respective inlet ports to ensure water flowing to the outlet 80 is at the desired temperature.

The temperature of the tap assembly 68 may be set permanently, or it may be adjustable by an adjustment facility 81. Such an adjustment facility may be connected to the water temperature adjustment spindle 32 of the mixer valve of Figures 2 and 3.

The arrangement shown in Figure 4 facilitates a substantially constant "°.outlet temperature, with available flow adjustment by the tap valve 69. The outlet temperature is not generally affected by changes to the cold water supply 15 pressure (although there may be small changes in normal operation), because the thermostatic controller can quickly alter the proportion of hot and cold water being mixed, to maintain substantially the same temperature prior to the flow change taking place. Moreover, because the temperature can be set, ***adjustment of the water flow through the tap valve 69 does not effectively alter the outlet temperature, and the tap assembly is easy to use because a single separate adjustment is required for changes in temperature or flow, but adjustment of one does not greatly affect the other.

Figure 5 is a cross-sectional view of a thermostatic mixer valve 100 according to another aspect of the invention, while Figure 6 is a perspective cross-sectional view of the same valve 100. The mixer valve 100 is of generally elongate form and includes a hollow valve housing 101. The valve housing 101 includes a thermostatic controller 102 which includes a push rod 103. The upper end 104 of the thermostatic controller 102 encloses an expandable/contractable wax material that acts on the push rod 103 and is fitted within an annular sleeve 105 which also receives the stem end 106 of an adjustment mechanism generally designated by the reference numeral 107.

The adjustment mechanism 107 is secured to an end cap 108, which is threadably connected to the upper end 109 of the valve housing 101. The lower edge 110 of the end cap 108 abuts against an upper face 111 of the annular 14 sleeve 105 so as to secure that sleeve against axial movement. The sleeve is further secured by a retaining ring 112 that secures the sleeve 105 adjacent its upper face 111, as well as adjacent its lower end 113. The retaining ring 112 is secured within the housing 101, against a radial step 114 in the internal surface 115 of the housing 101.

The mixing valve 100 includes a first inlet port 116 and a second inlet port 117. In practice, it is normal for the first inlet port 116 to be connected to a cold water, or unheated water supply, and for the second inlet port 117 to be connected to a hot or heated water supply. The housing 101 further includes a first outlet port 118 and a second outlet port 119. In practice, it is normal for the first outlet port 118 to be connected to a suitable water heater, for providing water for heating by the water heater, whereafter the heated water is returned to the valve through the second inlet port 117. The second outlet port 119 is the port through which mixed hot and cold water exits the valve 100.

The push rod 103 of the controller 102 extends and retracts relative to the remaining portion of controller 102 by respective expansion and contraction of the wax material enclosed therein. As shown, the controller 102 includes a tubular retaining portion 120 that retains one end of the push rod 103, while the other end of the push rod abuts against an internal surface 121 of a piston 122.

The piston 122 also includes a tubular retaining portion 123 and each of the ,.respective tubular retaining portions co-operate to hold the push rod 103 in position. Surrounding the respective tubular retaining portions 120 and 123, is the lower end 124 of the retaining ring 112. It is to be noted that the lower most end 125 of the end 124 includes a recess 126 for receiving an O-ring to seal against the outer surface of the tubular retaining portion 123, and that there is no engagement between the end 125 and the portion 123, so that relative movement between those parts is not restricted.

The piston 122 is biased toward engagement with the underneath surface 127 of the retaining ring 112 by a coil spring (not shown) which extends between the lower edge 128 of the piston 122 and the inwardly depending flange 129 of the valve housing 101. The piston 122 is movable between a first position as shown in Figure 5, in which the upper end of the piston engages the underneath surface 127 of the retaining ring 112, and a second position in which the piston is moved away from that engagement, by extension of the push rod 103.

Movement of the piston 122 serves to control flow of water through the valve 100. In this respect, cold water enters the valve 100 through the inlet port 116 and, depending on the position of the piston 122, can either flow through the piston (which as shown is hollow) and past the underneath surface 127 of the retaining ring 112, or it can flow past the lower edge 130 of the piston 122 and through the first outlet port 118. The respective flowpaths are illustrated by arrows. In the position shown in Figure 5, flow of water according to the flowpath A is prevented by engagement of the piston 122 against the underneath surface 127. Thus, all water entering the valve 100 through the first inlet port 116 flows past the lower edge 130 of the piston 122 and out through the first outlet port 118 according to the flowpath B. That water flows to a suitable heater, is heated, and then returns to the valve 100 through the second inlet port 117. Arrow C shows the flowpath of that water.

In the Figure 5 arrangement described above, the upper end 104 of the thermostatic controller 102 is exposed to heated water only, such that the push rod 103 extends under wax expansion, pushing the piston 122 downwardly and thus opening the flowpath A between the piston 122 and the underneath 20 surface 127 of the retaining ring 122. The water flowing through flowpath A enters a mixing chamber 131 in which both the heated water which has entered through the second inlet port 117, and the unheated water which has entered between the piston 122 and the underneath surface 127 is caused to mix.

Thus, the upper end 104 is then exposed to water at a reduced temperature, due to the influx of unheated water into the mixing chamber 131, and expansion of the wax in the upper end 104 may either slow, stop or contract as the temperature of the mixed water approaches, reaches or overshoots the set temperature of the thermostatic controller 102.

As is apparent, movement of the piston 122 away from the underneath surface 127 also restricts the flow of cold water through to the first outlet port 118 so that the action of downward movement of the piston 122 is such as to reduce the amount of unheated water which is tapped through the first outlet port 118 for heating.

16 The operation of the valve 100 is therefore such as to control the temperature of water which emerges from the second outlet port 119 to a set temperature.

A particular advantage of the valve 100, is that the flow passage C is a permanently open passage, so that heated water is able to be permanently vented through the valve 100 without the risk of pressure build-up. In particular, the flowpath C, is unaffected by the position of the piston 122.

A further advantage, as discussed earlier is that the piston 122 is positioned adjacent the first inlet port 116, so that throttling of inlet water pressure occurs prior to water flowing to the first outlet port 118, or past the underneath surface 127. Thus, the major portion of the valve 100 and the water heater (not shown) are subject to pressure loading below that existing at the first inlet port 116.

The position of the thermostatic controller 102 can be altered- by the og:• 15 adjustment mechanism 107, and this can be achieved in any suitable manner •A such as by a threaded head 132 that can be moved axially by rotation with respect to the housing 101. Movement of the threaded head 132 causes complimentary movement of the stem end 106 against the controller 102 such *e that the thermostatic element 103 and the piston 122 are also displaced axially.

The biasing influence of the coil spring maintains the piston 122 in connection with the push rod 103 regardless of the direction of displacement.

Figure 7 shows a further embodiment of a valve 200 according to the invention. The valve 200 includes many of the features of the valve 100, and these features are therefore designated by like numerals plus 100.

The major difference between the valves 100 and 200, is the position of the first inlet port 216, which is positioned in the side wall of the valve housing 201. The position of the first inlet port 216 necessitates a piston 222, which is of a different construction to that shown in Figure 5. The piston 222 includes an opening 240 which facilitates passage of water through the first inlet port 216 and into the valve housing 201. Depending on the position of the piston 222, water flowing through the first inlet port 216 can take either of the paths designated by the arrows D and E. As will be appreciated, downward movement of the piston 222 tends to restrict flow of water along the flowpath D, while upward of the piston 222 tends to restrict flow of water along the flowpath 4 1- 17 E. Otherwise, the valve works in substantially the same manner as that of the valve 100 shown in Figures 10 and 11 and no further description of the valve 200 is necessary.

The valves according to this aspect of the invention are suitable for attachment to a tap assembly and Figure 8 shows a suitable assembly. As shown, the tap assembly includes an inlet 300 for receipt of unheated water, which inlet is controlled by a tap valve 301 which can be of any suitable form.

For example, the tap valve 301 can be a simple screw valve having a head 302 which can seat in the closed condition of the valve, against a seat 303.

Movement of the head 302 toward and away from the seat 303 is by a threaded spindle 304 which is turned in a threaded opening 305 in the tap assembly 306.

The opening 300 is arranged to be connected to a supply of cold or unheated water and in an opened condition of the tap valve 301, water flows in the direction shown to the thermostatic valve 307. The thermostatic valve 307 15 can for example, be in accordance with either of valves 100 or 200 shown in Figures 5 to 7. According to the earlier description, depending on the position of the piston 122, 222 in the valve 307, a proportion of the water entering that valve is diverted to a water heater via the passage 308, while the remaining 5 portion of the water remains within the valve for mixing with heated water, 20 before flowing out of the valve and through the outlet 309 of the tap assembly 306. Water which is diverted to the heater through the passage 308, returns to the valve 307, through the passage 310, whereafter it is mixed with the portion of the unheated water and the mixed water then flows out through 9 i the outlet passage 309.

The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.

Claims (17)

1. A thermostatic mixer valve, including a valve housing having first and second inlet ports for connection to a supply of cold water and a supply of hot water respectively, said first and second inlet ports being arranged for respective communication with first and second flow passages which communicate with a mixing chamber, said mixer valve further including first and second outlet ports, said first outlet port being in communication with said first flow passage and in use, with water heating means, and whereby flow of water from said first passage through said first outlet port to said water heating means and from said first flow passage to said mixing chamber is controlled by thermostatic control means, said control means including a movable member which is movable in a first direction to reduce the amount of water which can flow to said first outlet port and increase the amount of water which can flow to 15 said mixing chamber and in a second direction to increase the amount of water which can flow to said first outlet port and decrease the amount of water which can flow to said mixing chamber, said thermostatic controller reacting to the ***temperature of mixed water to move said movable member in either said first or 9 second directions upon deviation of the mixed water temperature from a preset 20 temperature, said second inlet port being in use, in communication with said water heating means to receive heated water therefrom afterwhich it can flow through said second flow passage into said mixing chamber, said second outlet port being in communication with said mixing chamber for dispensing mixed water therefrom.

2. A thermostatic mixing valve according to claim 1, said movable member being in the form of a cylindrical piston and said piston at least partially defining said first flow passage.

3. A thermostatic mixing valve according to claim 2, said thermostatic controller including a plunger which acts on said piston to move it in either of said first or second directions upon the temperature of mixed water deviating from said preset temperature. F I- 19

4. A thermostatic mixing valve according to claim 3, said piston including an abutment face for abuting engagement with said plunger, said abutment face being formed radially across one end of said piston.

5. A thermostatic mixing valve according to any one of claims 2 to 4, said first flow passage including an opening for communication with said first inlet port and said piston being disposed for movement within said first flow passage across said opening for controlling the amount of water flow from said first flow passage to said first outlet port.

6. A thermostatic mixing valve according to any one of claims 2 to wherein said first inlet port communicates with said first flow passage through an opening in said piston. 15 7. A thermostatic mixing valve according to any one of claims 2 to 6, said piston being arranged to move in said first direction against biasing means disposed in said first flow passage.

8. A thermostatic mixing valve according to any one of claims 2 to 7, said e" 20 piston being arranged to abut respective valve seats at the maximum travel in said first and second directions. A thermostatic mixing valve according to claim 6 or 7 when dependent on claim 5, the portion of said first flow passage upstream of and adjacent said opening having an internal diameter slightly greater than the outer diameter of the piston such that the end of said piston can be received within said portion of said first flow passage upon maximum travel of said piston in said first direction. A thermostatic mixing valve according to claim 9, said piston being arranged to abut a valve seat at the maximum travel in the second direction.

11. A thermostatic mixing valve according to any preceding claim, said valve including adjustment means for adjusting the position of said movable member within said valve housing, so that said preset temperature may be adjusted. I 1

12. A thermostatic mixing valve according to claim 11, said adjustment means including a manual adjuster which is operable to adjust the position of said thermostatic controller within the valve housing, and so adjusting the position of said movable member.

13. A thermostatic mixing valve according to claim 12, said adjuster including a rotatable element which is threadably connected to a member which is movable axially upon rotation of said element, axial movement of said member resulting in axial movement of said thermostatic controller and said movable member.

14. A thermostatic mixer valve substantially as herein described with reference to any one of Figures 5 to 7. 15 15. A mixer tap, including a thermostatic mixer valve according to any one of claims 1 to 14, said tap further including a tap inlet port for connection to a cold water supply, whereby in use, flow of cold water through said tap inlet port being controlled by valve means, said tap inlet port being arranged for communication with said first inlet port of said mixer valve for supply of cold 20 water thereto, said mixer tap further including a tap outlet flow passage for communication with said first outlet port and a water heater, and a tap inlet flow passage in communication with said water heater and said second inlet port, to permit flow of water from said first outlet port to the water heater and from the water heater to said second inlet port, and a tap dispensing flow passage in communication with said second outlet port for dispensing water mixed in said mixer valve.

16. A thermostatic mixer valve, including a valve housing having first and second inlet ports for connection to a supply of cold water and a supply of hot water from hot water heating means respectively, said first and second inlet ports being arranged for respective communication with first and second flow passages which communicate with a mixing chamber, thermostatic control means is provided for controlling flow of water from said first and second inlet ports to said first and second flow passages, said control means including a 4 AW 21 movable member which is movable by a thermostatic controller in a first direction to reduce flow of water through said first inlet port and increase flow of water through said second inlet port, and in a second direction, to increase flow of water through said first inlet port and to decrease flow of water through said second inlet port said thermostatic controller reacting to the temperature of mixed water to move said movable member in either of said first or second directions upon deviation of the mixed water temperature from a preset temperature, said movable member having maximum movement in said first direction to at least substantially close communication between said first inlet port and said first flow passage and having maximum movement in said second direction to substantially close communication between said second inlet port and said second flow passage, said mixer valve further including an outlet port in communication with said mixing chamber for dispensing water therefrom. I 15 17. A thermostatic mixer valve according to claim 16, said movable member being in the form of a hollow piston and said first flow passage extending through the interior of said piston.

18. A thermostatic mixer valve according to claim 17, said thermostatic 20 controller including a housing and a plunger which is arranged so that said housing moves relative to said plunger upon deviation of the mixed water temperature from a preset temperature, said piston being movable with said S" housing in either of said first or second directions.

19. A thermostatic mixer valve according to claim 18, said valve including biasing means for biasing said thermostatic controller against movement of said piston in said second direction. A thermostatic mixer valve according to any one of claims 16 to 19, said valve including adjustment means for adjusting the position of said movable member within said valve housing, so that said preset temperature may be adjusted. -4 .l I- 22

21. A thermostatic mixer valve according to claim 20, said adjustment means including a manual adjuster which is operable to adjust the position of the thermostatic controller within the valve housing and so adjusting the position of said movable member.

22. A thermostatic mixer valve according to any one of claims 17 to 21, said piston being cylindrical and being arranged at one end thereof to abut a valve seat at the maximum travel in the first direction so as to close flow between said first inlet and the first flow passage, and further being arranged at the other end thereof to be received closely within a cylindrical portion of said housing at the maximum travel in the second direction, said receipt being such as to substantially close flow between said second inlet and said second flow passage, but to allow hot water leakage therepast. 15 23. A thermostatic mixer valve according to claim 22, said valve housing being generally cylindrical with said first inlet being disposed adjacent the abutting valve seat and said second inlet being disposed adjacent said o ocylindrical portion of said valve housing, said mixing chamber being disposed coaxially adjacent said cylindrical portion and said outlet port being disposed 20 coaxially adjacent said mixing chamber, said thermostatic controller being disposed coaxially within said valve housing between said abutting valve seat and said outlet port. SO

24. A thermostatic mixer valve substantially as herein described with reference to any one of Figures 2 or 3. A mixer tap, including a thermostatic mixer valve according to any one of claims 16 to 24, said tap further including a tap inlet port for connection to a cold water supply, flow of cold water through said tap inlet port being controlled by valve means, said tap inlet port being in communication with first and second tap flow passages, said first tap flow passage communicating with said first inlet port of said mixer valve while said second tap flow passage communicates in use, with the inlet of a water heater, a third tap flow passage communicates in use, both with the outlet of the water heater for receipt of heated water, and with 0 23 said second inlet port of said mixer valve, water from said first and third tap flow passages being mixed in said mixer valve and said tap including an outlet flow passage for dispensing the mixed water. DATED: 22 March 2000 PHILLIPS ORMONDE FITZPATRICK Attorneys for: GSA INDUSTRIES (AUST.) PTY LTD W:NSKARONAnrPCTCOMP576847dalffr.doc @0 0