GB2516897A

GB2516897A - A Thermostatic Mixing Valve

Info

Publication number: GB2516897A
Application number: GB1313995.1A
Authority: GB
Inventors: Christopher Jonathan Taylor; Ian Robert Lloyd
Original assignee: Bristan Group Ltd
Current assignee: Bristan Group Ltd
Priority date: 2013-08-05
Filing date: 2013-08-05
Publication date: 2015-02-11
Anticipated expiration: 2033-08-05
Also published as: GB201313995D0; GB2516897B

Abstract

A thermostatic mixing valve body 12 comprises hot and cold water inlet ports 14, 16 and a mixing chamber 56 receiving a thermostatic mixing valve cartridge 112. The body has a hot water passageway 54 extending between the hot water inlet 14 and the mixing chamber 56 and a cold water passageway 52 extending between the cold water inlet 16 and the mixing chamber 56. The body also has a bypass passageway 90 extending between the hot and cold water passageways 54, 52 upstream of the mixing chamber 56 and a bypass valve 94 arranged to selectively block the bypass passageway 90. The body has an isolating valve 64 to selectively block an opening 66 of the cold water passageway 52 upstream of the bypass passageway 90. The isolating valve 64 has an actuation mechanism accessible from the exterior of the valve body.

Description

A Thermostatic Mixing Valve Thc invcntion relates to thermostatic mixing valves for mixing hot and cold watcr flows to produce a mixcd water outlet flow.

Thermostatic mixing valves are used upstream of a shower head or the like for setting the temperature and, optionally, flow rate at the shower head.

Known thermostatic mixing valves comprise respective hot and cold water supply pipes connected to a valve body. The body comprises a number of internal passagcways, a mixcd watcr outlct and a thcrmostatic mixing valvc cartridgc. Thc passageways include a cold water passageway directing water from the cold water inlet to the mixing valve cartridge and a hot water passageway connecting the hot water inlet to the mixing valve cartridge. The mixing valve cartridge has an outlet coupled to the mixed water passageway which is arranged to direct mixed temperature water from the mixing valve cartridge to the mixed water outlet.

It is known to flush hot water from the hot water supply pipe through the mixed water passageway in the absence of cold water. GB245 1800 describes such a mixing valve apparatus. GB245 1800 directs only hot water through the cartridge and into the mixed water passageway by first actuating an isolating valve provided on the cold watcr supply pipe then actuating a bypass valve arrangcd between the hot water passageway and the cold water passageway upstream of the mixing valve cartridge.

It is an object of the present invention to provide a thermostatic mixing valve body

which further improves on the prior art.

According to a first aspect of the present invention there is provided a thermostatic mixing valve body comprising respective hot and cold water inlet ports for conncction to respective hot and cold water supply pipes and a mixing chamber arranged to receive a thermostatic mixing valve cartridge, the body further comprising a hot water passageway extending between the hot water inlet port and the mixing chamber, a cold water passageway extending between the cold water inlet port and the mixing chamber, a bypass passageway extending between the hot and cold water passageways upstream of the mixing chamber, a bypass valve arranged to selectively block the bypass passageway, and an isolating valve in the body arranged to selectively form a blockage of the cold water passageway upstream of the bypass passageway, wherein the isolating valve comprises an actuation mechanism accessible from an exterior surface of the valve body.

The provision of the isolating valve in the body accessible from an exterior surface of the valve body as opposed to the isolating valve being located on the cold water supply pipe allows for the flushing system to be used with a wider range of inlet types.

For example, supply pipes oflen have a short length where it can be difficult to accommodate an isolating valve. Also, for supply pipes using a shrouded wall mount fitting which has screw threaded shrouds which is sometimes advantageous over the alternative pull back fittings the present arrangement is preferable.

The isolating valve may comprise a threaded screw.

The isolating valve may comprise a plug portion arranged to sealingly engage an opening in the cold water passageway to form the blockage. The plug and opening combination is a simple and reliable way to achieve a blockage. The valve may be actuated by an elongate tool such as a screw driver, hexagonal key or preferably a key with a bespoke design to ensure only authorised personnel may access it.

The isolating valve may further comprise an 0-ring arranged to fit intermediate the plug and opening when fitted together. The 0-ring further enhances the fluid seal.

The body may further comprise a threaded bushing received on the surface of the body, the bushing being arranged to captively receive the threaded screw. In such a case, the bushing has a bore therethrough to allow access to the isolating valve by an actuating tool. The bushing further enhances the water tight seal between the threaded screw and the body and prevents untimely removal of the screw from the body.

The bushing may be arranged to screw fit with the surface of the body. The bushing may comprise a surface formation arranged to engage with a dedicated bushing fitting tool. This allows access to removal of the threaded screw to be controlled to authoriscd persons.

The surface formation may comprise a plurality of circumferentially arranged indentations. There may be two diametrically opposed indentations either side of the bore. Such a surface formation prevents the bushing from being removed with the standard off the shelf fitting tools such as scrcw drivers or thc like. Maintenance personnel can then be provided with a bespoke tooling having a corresponding pair of diametrically opposed protrusions.

The bypass valve may comprise a threaded screw.

The bypass valve may comprise a plug portion arranged to sealably engage an opening in the bypass passageway to selectively open and block the passageway. Like the isolating valve, the plug and opening is a simple and effective way of forming the blockage. The bypass valve may further comprise an 0-ring arranged to fit intermediately the plug and opening when fitted together. This further enhances the fluid seal.

A bypass valve bushing substantially the same as the isolating valve bushing may be provided. This allows for the same advantages to be provided to the bypass valve as thc isolating valvc. Also, thc samc tooling can be uscd for surface formations of both bushings.

The opening of the cold water passageway may be arranged to divide the cold water passageway into an upstream and a downstream portions. The upstream portion should be as small as possible and preferably has a volume of less than 20% of the total volume of the cold water passageway. The upstream portion is preferably less than 10% of the total cold water passageway volume. Limiting the volume of the upstream portion in this way allows for most of the cold water passageway, ie the downstream portion being flushed with hot water during a flushing operation.

According to a second aspect of the present invention there is provided a thermostatic mixing valve apparatus comprising a cold water supply pipe and a hot water supply pipe passing through a wall and a thermostatic mixing valve body as described hereinabove wherein the hot and cold water supply pipes are coupled to the hot and cold water inlet ports of the body.

The hot andior cold water supply pipes may be threadingly engaged with a threaded wall mount shroud. The hot and cold water supply pipes may be relatively short in length.

One embodiment of the invention is described in detail with reference to the accompanying drawings, in which: Figure 1 shows an exploded perspective view of a thermostatic mixing valve apparatus according to both aspects of the present invention; Figure 2 shows an exploded top view of the apparatus of figure 1; Figure 3 shows an above section vicw of the apparatus of figure 1 during normal operation; and Figure 4 shows a similar view to figure 3 for the apparatus during a flushing operation.

With reference to figures 1 to 4, a thermostatic mixing valve apparatus 10 comprises a thermostatic mixing valve body 12 connected to a hot water supply pipe 14 and a cold water supply pipe 16.

The hot and cold water supply pipes 14, 16 each comprise the same components so it is only necessary to describe one in detail. The hot water supply pipe 14 comprises a wall mount fitting 18 arranged to fit to a bathroom wall (not shown). The fitting 18 has an annular skirt 20 surrounding an internally threaded apcrturc 21. A supply pipe shroud 22 is arranged to threadingly engage to the internally threaded aperture 21. Thc supply pipe shroud 22 encases the supply pipe 16 for aesthetic reasons and also to provide thermal insulation to a user. The supply pipe shroud 22 is a hollow cylinder allowing access to a hot water mains pipe 24. The hot water mains pipe 24 is threaded along its length and has flats 26 formed to allow a tightening tool such as a wrench to engage with it. The supply pipe 14 further comprises a filter 28, a flow restrictor 30, and a check valve 32 arranged sequentially in the water flow direction.

The filter 28 prevents particles in the water entering the body 12. The flow restrictor limits the flow rate of the water entering the body 12. The check valve 32 prevents water from the body 12 back flowing into the hot water mains pipe 24. A supply pipe bushing 34 is provided and arranged to couple to a hot water inlet port 36 of the valve body 12. The supply pipe bushing 34 comprises a neck portion 38 arranged to couple to a protruding annulus 40 inside the hot water supply pipe 40 for coupling the two together by screw fit.

An 0-ring 42 is provided to fit between the hushing 42 and the valve body 12 to provide a fluid tight seal. The supply pipe 14 further comprises a nut 44. The nut 44 is held eaptively in compression against the body 12 around the bushing 34 by a lip 46 provided on the bushing 34. The nut 44 is partially internally threaded so as to threadingly engage threaded end 26 of the hot water mains pipe 24. The nut 44 comprises a plurality of axial flat faces 48 arranged to engage axial ribs 50 arranged around the intemal periphery of the supply pipe shroud 22. The nut 44 and supply pipe shroud 22 are thus axially disengaged and rotatably engaged with one another. In this way, tuning the supply pipe shroud 22 clockwise or antielockwise causes the nut 44 to tighten or loosen respectively on the pipe 24.

As only the hot water supply pipe 14 is described in detail, it will be appreciated that the cold water supply pipe 16 comprises the same components extending between a cold water pipe 25 and a cold water inlet port 37 on the valve body 12.

The hot and cold water supply pipes 14,16 are not defined as part of the valve body 12. The hot and cold water supply pipes 14, 16 transfer water from the respective mains pipe 24 to the respective hot and cold water inlet port 36, 37. The hot and cold water inlet ports 36, 37 are the entry points for hot and cold water respectively into the valve body 12. The hot and cold water inlet ports 36, 37 are connectable to the respective hot and cold water supply pipes.

The body 12 comprises a number of internal passageways. Those passageways include a cold water passageway 52, a hot water passageway 54, a mixing chamber 56 and a mixed water passageway 58. The cold water passageway 52 is divided into an upstream portion 60 and a downstream portion 62. The upstream portion 60 has a volume of less than 10% of the total volume of the cold water passageway. This percentage may be increased but is preferably less than 20% of the total volume of the cold water passageway.

An isolating valve 64 is provided in the body 12 to selectively form a blockage in an opening 66 of the cold water passageway 52 between the upstream portion 60 and the down stream portion 62. The isolating valve 64 comprises a bushing 68 arranged to screw fit into a counter bored hole 70 provided on an external surface 72 of the valve body 12. The bushing 68 is internally threaded. The isolating valve 64 further comprises a threaded screw 74 forming an actuating means having a plug 76 at one end. The threaded screw 74 is arranged to threadingly engage the internal surface of the bushing 68. The plug 76 is arranged at the interior of the body 112 when assembled so that the threaded screw 72 is held captive by the bushing 68. The plug 76 is arranged to sealingly engage the opening 66 of the cold water passageway 52.

Three O-rings78, 80, 82 are provided as part of the isolating valve 64 to prevent leakage. One 0-ring 78 is provided to sit between the plug portion 76 and the opening 66 of the cold water passageway. A second 0-ring 80 is provided to sit between the and the bushing 68 and a third 0-ring 82 is provided to sit between the threaded screw 74 and the bushing 68.

The bushing 68 comprises an outer face 84 (not shown) having two diametrically opposed indentations. The indentations are preferably 3 to 4 mms in diameter. The indentations are arranged to fit a bespoke tool for screwing the bushing into the valve body and prevent removal of the threaded screw. The threaded screw 74 is provided with a conventional screwdriver type outer surface pattern for receiving a phillips or hexagon or flathead screw driver. Alternatively, a bespoke form tool may be required.

The outer surface of the threaded screw 74 is arranged so as to be accessible from the exterior of the body 12.

The downstream portion 62 of the cold water passageway extends from the cold water side of the valve body 12 to the hot water side of the valve body 12. Although not shown in the section views, the downstream portion 62 of the cold water passageway surrounds the other aforementioned passageways 54, 56, 58. The downstream portion 62 of the cold water passageway comprises an annular opening 86 leading to the mixing chamber 56.

The hot water passageway 54 extends between the hot water inlet port 36 and an opening 86 leading to the mixing chamber 56. The hot water passageway 54 comprises a bypass passageway 90. The bypass passageway 90 is elongate and terminates at an opening 92 leading to the downstream portion 62 of the cold water passageway.

A bypass valve 94 is provided to selectively form a blockage in the opening 92 of the bypass passageway. The bypass valve 94 is similar in form to the isolation valve 64 and comprises the same components differing only in terms of dimension and shape.

Specifically, the bypass valve 94 comprises a bushing 96 arranged to screw fit into a counter sunk hole 98 on the external surface 72 of the valve body as the isolating valve 64. The bushing 96 is internally threaded so as to receive a threaded screw 100 forming an actuating means. The threaded screw 100 has a plug portion 102 at one end. The plug portion 102 is arranged to sealingly fit into the opening 92 of the bypass passageway. Three 0-rings 104, 106, 108 are again provided to sit between the plug 102 and opening 100, the plug 102 and the bushing 96, and the threaded screw 100 and the bushing 96 respectively. An outer surface 110 of the bushing comprises two diametrically opposed indentations (not shown). The indentations are the same as those of the isolating valve 64. This allows for the same bespoke tool to be used for both valves 64, 94.

A thermostatic mixing valve cartridge 112 is provided at the hot water side of the valve body 12 through an opening 114. The cartridge 112 is of a conventional type and is not described in any great detail here. A temperature control knob 116 is arranged to engage with the cartridge 112 in a conventional manner. The cartridge 112 is fluidly coupled to the annular opening 86 of the downstream portion 62 of the cold water passageway and the annular opening 88 of the hot water passageway 54.

The cartridge 112 has an exit nozzle 118 arranged to protrude into the mixing chamber 56.

The mixing chamber 56 has a converging portion and a diverging trumpet shaped portion. The trumpet shaped portion terminates at an opening 120 leading to the mix water passageway 58. A ceramic disk valve 122 is inserted through a hole 124 in the cold water side of the body 12 through the mixed water passageway 58. The ceramic disk valve 122 is of conventional form and is not described in any great detail here.

The ceramic disk valve 122 is coupled to a flow rate control knob 126 in a conventional manner. The ceramic disk valve 122 is arranged to engage the opening between the mixing chamber 56 and the mixed water passageway 58. The mixed water passageway 58 then leads to a mixed water exit port 128. An outlet fitting 130 is coupled to the exit port 130 and has an 0-ring 132 therebetween to enhance the fluid seal.

Particularly with reference to figures 3 and 4, the isolating valve 64 and the bypass valve 94 can be set so that the thermostatic mixing valve body 12 performs either a normal operation or a flushing operation. The normal operation will be described first followed by the flushing operation.

With reference to figure 3, in normal operation the plug 102 of the bypass valve 94 is distanced from the opening 66 of the cold water passageway 52 so that cold water may flow from the upstream portion 60 to the downstream portion 62. Cold water, particularly between 5-15°C flows to the hot water side of the body 12 and through to the caiuidge 112 through the angular opening 86. Hot water, typically in excess of 55°C, enters the body through the hot water inlet port 36 and continues to the cartridge 112 via the hot water passageway 54 then the opening 92. Depending on the setting of the cartridge 112 according to the position of the temperature control knobi 16, a pre-determined quantity of hot and cold water enters the cartridge 112 and exits through the exit nozzle 118. Mixed temperature water is typically in the temperature range from about 30-40°C. The mixed temperature water exiting the exit nozzle 118 enters the mixing chamber 56. The ceramic disk valve 122 aHows a pre-determined flow rate of mixed temperature water to enter the mixed water passageway 58 depending on the position of the flow rate control knob 126. Mixed temperature water at a given flow rate then exits the valve body 12 through the mixed temperature water outlet port 128.

With reference to figure 4, the flushing operation is commenced by screwing the threaded screw 74 of the isolating valve 64 so that the plug 76 cooperates with the opening 66 in the cold water passageway 52 so as to form a blockage. Thc upstream portion 60 and the downstream portion 62 of the cold water passageway 52 are therefore fluidly isolated from one another. The threaded screw 100 of the bypass valve 94 is turned so as to remove the plug 102 from the opening 92 of the bypass passageway 90. Hot water is thus allowed to flow to the entire upstream portion 62 of the cold water passageway 52 from the hot water passageway 54. Hot water entering the cartridge 112 through the annular opening 88 in the hot water passageway 54 initially causes the cartridge 112 to restrict the quantity of hot water and increase the quantity of cold water entering. The remaining cold water is flushed through the cartridge 112 to a steady state where only hot water is entering the cartridge 112 through annular opening 86 of the cold water passageway 52. The balanced temperature of water entering the cartridge 112 through both annular openings 86, 88 causes the cartridge to remain open to hot water entering from the cold water passageway 52 and the hot water passageway 54. This forces hot water only through the cartridge 112 into the mixing chamber 56. The hot water passes through the mixed water passageway 58 and out of the valve body 12 through the mixed water exit port 128. The presence of hot water, typically above 55°C, in the mixing chamber 56 and the mixed water passageway 58 is sufficient to kill off any bacteria present.

The flushing operation lasts for enough time to sterilise the mixed water passageway 58 and the mixing chamber 56. After the pre-determined amount of time for the flushing operation, the bypass valve 94 and the isolating valve 64 are re-configured by turning the respective threaded screws 100, 74 so that normal operation of the valve body 12 may re-commence.

The provision of the isolating valve 94 on the valve body 12 instead of on the cold water supply pipe, as described in 0B245 1800, allows for relatively short supply pipes 14, 16 to be used together with threaded shroud 22 mounting arrangements which would be difficult if the isolating valve 64 was provided on the supply pipe itself 14, 16.

The isolating valve 64 and the bypass valves 94 may also be modified, for example by changing the surface arrangements of the bushings 96, 68. For example, the surface arrangement could include a plurality of indentations around the circumference. The exact surface arrangements depends on a tool with which the bushing 96, 68 should engage in order to remove the valve from the body.

Claims

Claims 1. A thermostatic mixing valve body comprising respective hot and cold water inlet ports for connection to respective hot and cold water supply pipes and a mixing chamber arranged to receive a thermostatic mixing valve cartridge, the body further comprising a hot water passageway extending between the hot water inlet port and the mixing chamber, a cold water passageway extending between the cold water inlet port and the mixing chamber, a bypass passageway extending between the hot and cold water passageways upstream of the mixing chamber, a bypass valve arranged to selectively block the bypass passageway, and an isolating valve in the body arranged to selectively form a blockage of the cold water passageway upstream of the bypass passageway, wherein the isolating valve comprises an actuation means accessible from an exterior surface of the valve body.
2. The body of claim 1 wherein the actuation means comprises a threaded screw.
3. The body of claim I or claim 2 wherein the isolating valve comprises a plug arranged to sealingly engage an opening of the cold water passageway to form the blockage.
4. The body of claim 3 wherein the isolating valve further comprises an 0-ring arranged to fit intermediate the plug and opening when fitted together.
5. The body of any of claims 2 to 4 further comprising a threaded bushing received on the surface of the body, the bushing arranged to captively receive the threaded screw.
6. The body of claim 5 wherein the bushing is arranged to screw fit with the exterior surface of the body.
7. The body of claim 6 wherein thc bushing comprises a surface formation arranged to engage with a fitting tool.
8. The body of claim 7 wherein the surface formation comprises a plurality of circumferentiafly arranged indentations.
9. The body of claim 8 having two diametrically opposed indentations.
10. The body of any preceding claim wherein the bypass valve comprises a threaded screw.
11. The body of any preceding claim wherein the bypass valve comprises a plug portion arranged to scalably engage an opening of the bypass passageway to selectively open and block the passageway.
12. The body of claim 10 or claim 11 further comprising a threaded bushing received on the surface of the body, the bushing arranged to receive the threaded screw.
13. The body of claim 12 wherein the bypass valve bushing is substantially the same as the isolating valve bushing of any claims 5 to 8.
14. The body of claim 3 or any claim based thereon wherein the opening of the cold water passageway divides the cold water passageway into an upstream and a down stream portions.
IS. The body of claim 14 wherein the upstream portion has a volume of less than 20% of the total volume of the cold water passageway.
16. The body of claim 15 wherein the upstream portion has a volume of less than 10% of the total volume of the cold water pasasgeway.
17. A thermostatic mixing valve apparatus comprising a cold water supply pipe and a hot watcr supply pipc passing through a wall, thc apparatus fiirthcr comprising a thermostatic mixing valve body according to any preceding claim, a thermostatic mixing valve cartridge is received within the mixing chamber, and wherein the hot and co'd water supply pipes are coupled to the hot and cold water in'et ports of the body.
18. The thermostatic mixing valve apparatus of claim 16 wherein the hot and/or cold water supply pipes are threadingly engaged with a threaded wall mount shroud.
19. The thermostatic mixing valve of claim 17 or claim 18 wherein the hot and cold water supply pipes are relatively short in length.
20. A thcrmostatic mixing valve body substantially as described herein with reference to the accompanying figures.
21. A thermostatic mixing valve apparatus substantially as described herein with reference to the accompanying figures.