GB2448670A

GB2448670A - Valve assembly

Info

Publication number: GB2448670A
Application number: GB0708283A
Authority: GB
Inventors: Thomas Mccarthy; Paul Barton; Thomas Andrew Heaps; Graham Keith Lacy; Nick Gerald Fitton; Barry Lillis; Matthew Spencer Jaynes Candy
Original assignee: Baxi Heating UK Ltd
Current assignee: Baxi Heating UK Ltd
Priority date: 2007-04-28
Filing date: 2007-04-28
Publication date: 2008-10-29
Anticipated expiration: 2027-04-28
Also published as: GB2448670B; GB0708283D0

Abstract

A valve assembly positioned between an external water supply and a central heating system automatically or manually tops up the central heating system with water to the required pressure in response to pressure loss within the circuit. It is also configured to create and maintain an air gap between the mains water supply and the central heating system to prevent back-flow of water from the central heating system into the mains water supply. The valve assembly may automatically isolate the central heating system from the mains water supply following water top-up to avoid over-pressurization of the system. To this end a method of controlling fluid supply comprises introducing the fluid via a supply inlet 101 into a valve assembly; allowing the fluid to flow from the inlet to a first chamber 103; utilising chamber valve means to prevent fluid from flowing into a second chamber 104; draining any fluid present within the second chamber via a drain outlet 130; and opening the chamber valve means to allow fluid to flow from the valve assembly via a supply outlet 102.

Description

VALVE ASSEMBLY

Field of the Invention

The present invention relates to a valve assembly and in particular, although not exclusively, to a valve assembly configured to control the flow of a fluid between a fluid supply source and a fluid circuit.

Background to the Invention

Domestic and commercial central heating systems may be divided into two categories: open or sealed fluid systems. Sealed systems typically involve the circulation of water independently of the building's mains water supply and are commonly associated with combination boilers which require water be circulated under pressure so as to achieve optimum heating efficiency. More traditional open or vented systems comprise a header tank and a cold water storage cistern located in the uppermost region of the building well above the boiler and heat exchanger. Water is fed into the central heating system from the storage system which is fed by the mains water supply. In the event of the system degassing, commonly referred to as bleeding', or water loss due to leakage, topping-up of the system with water is provided by the header tank which feeds water into the boiler under gravity.

Repressurisation of closed central heating systems in response to bleeding or water leakage requires a connection of the system directly to the mains water supply so as to refill and pressurise the system to the required operating conditions typically one bar for domestic applications.

Owing to the fact that as the fluid within the central heating system becomes contaminated over time, legislation in certain territories prohibits permanent connection of the central heating circuit to the mains supply to avoid cross contamination of the mains supply by back-flow' of water from the central heating circuit. This requirement has led to the development of temporary connections to couple the mains supply to the central heating circuit to allow manual repressurisation in the event of degassing or liquid loss.

GB 2204669 discloses a water connection device configured to connect the mains water supply to a central heating system and comprises a flexible pipe, flow regulator and non-return valve. The connection device allows fluid to flow from the mains supply to the central heating circuit but prevents reverse flow.

Attachment and removal of a temporary connector of the type disclosed in GB 2204669 is inconvenient and inefficient as a qualified service engineer is typically required to perform the task where the end user is incapable and/or not confident in doing so.

GB 2300695 attempts to address the above problem by providing a valve supply assembly configured to be permanently connected between the mains water supply and the central heating system. To satisfy legislation and prevent back-flow of water from the central heating system, a removeable connector is positioned within the assembly such that when not in use the connector is removed from the assembly to create an air gap between the mains supply and the central heating system preventing any back-flow of water.

The connection device of GB 2300695 is not suitable for use by the elderly and infirm who may find it difficult manipulating the removeable connector into position so as to establish the high pressure water joint. Additionally, once removed, the connector may become lost rendering the connector useless.

What is required is a valve assembly that addresses the above problems.

Summary of the Invention

The inventors provide a valve assembly configured to be permanently connected between the mains water supply and a central heating circuit enabled with manual and/or automatic valve control according to specific implementations. The valve assembly allows water to be supplied into the central heating system on demand in the event of pressure loss within the system resulting from water leakage and/or air bleeding from the system.

The valve assembly is configured to be self-draining between topping-up' intervals so as to avoid stationary water standing within the valve assembly which would otherwise provide an incubation environment for bacteria such as legionella.

The present invention is configured to be permanently connected between the mains water supply and the central heating system obviating the requirement for a specialised service engineer to connect and disconnect the mains supply to the main water circuit. When not operating to enable the water from the mains supply to flow into the primary circuit of the heating system, an air gap is created within the assembly between the mains supply and the heating system. This satisfies legislation in certain jurisdictions including, for example, the United Kingdom. The present valve assembly may be retro-fitted to existing central heating systems according to specific implementations or may operate with specifically designed boilers, in particular, combination boilers and appropriate non-vented fluid based central heating systems for both domestic and commercial environments.

According to a first aspect of the present invention there is provided a valve assembly configured to be positioned between a fluid supply source and a fluid circuit, said valve assembly comprising: a supply inlet to allow fluid from said supply source to flow into said valve assembly; a first chamber, said supply inlet provided at said first chamber; a second chamber provided in fluid communication with said first chamber; chamber valve means operable to allow and prevent fluid communication between said first and second chambers; a drain outlet provided at said second chamber configured to allow fluid to drain from said chamber; a supply outlet to allow fluid from said supply source to flow out of said valve assembly, said supply outlet provided at said second chamber; and drain valve means operable to reverseably open and close said drain outlet.

Preferably, the chamber valve means and the drain valve means are operable such that the drain valve is either opened or closed before the chamber valve means is opened or closed. This way, fluid is always drained from the second chamber prior to fluid being supplied into the central heating system from the mains. Additionally, fluid under pressure from the mains supply is prevented from simply flowing through the drain outlet and not into the primary circuit of the heating system.

Preferably, the assembly further comprises control means to control operation of the chamber valve and drain valve means. The control means may be located at the valve assembly or may be integrated within the boiler in particular a combination boiler. The control means may comprise printed circuit boards, pressure transducers, pressure sensors and the like as will be appreciated by those skilled in the art. In particular, actuation of the valve means within the assembly may be provided by suitable actuators including at least one solenoid and/or electronically controlled actuators including electromagnetic actuators. The present valve assembly may therefore by automated for operation in response to pressure levels within the central heating system and responsive to restore the pressure to a predetermined level by the introduction of mains water into the system.

Preferably, the assembly further comprises at least one non-return valve positioned at the supply inlet. Preferably, two non-return valves are positioned at the supply inlet to prevent back-flow of water within the assembly to the mains supply. Additionally, the valve assembly may comprise at least one non-return valve positioned at the supply outlet, in particular two non-return valves positioned at the supply outlet.

According to a specific implementation, the assembly comprises a moveable shaft extending through the first and second chambers configured to move in its axial direction. The assembly may comprise first seal means connected to the shaft at the region of the interface between the first and second chambers such that movement of the shaft provides movement of the seal means in the axial direction of the shaft whereby movement of the shaft provides an opening and a closing of the fluid communication between the first and second chambers. Alternatively, the seal means may be located within the assembly housing at the interlace between the first and second chambers. As the first shaft moves in its axial direction, the seal means would be contacted and compressed to close the inter-chamber fluid passageway between the first and second chambers. Preferably, at least one actuator is connected to one end of the moveable shaft configured to provide movement of the shaft in the axial direction.

Preferably, the second seal means, positioned at the drain outlet comprises a through-bore which provides a fluid passageway through the second seal means between the second chamber and an external region. The through-bore serves as a release for any hydraulic lock which would otherwise prevent release of the drain valve means to open upon or following termination of the flow of water through the assembly.

Preferably, the assembly comprises bias means configured to bias the moveable shaft in an axial direction opposed to the direction of movement provided by the actuator. That is, the bias means is configured to bias the chamber valve means into a closed position and the drain valve means into an open position. Optionally, the bias means comprises at least one spring, in particular a coil spring.

According to a specific implementation, the assembly may comprise a first shaft extending through the second chamber, the first shaft being rotateable about it longitudinal axis. Preferably, a first cam is provided on the first shaft such that on rotation of the shaft, the cam is configured to releaseably open and close the drain outlet by sealing the drain outlet aperture as the outer surface of the cam is brought into position to cover it.

Preferably, the valve assembly comprises a second shaft aligned substantially transverse to the first shaft and positioned to extend through a part of the first and second chambers, the second shaft is configured to move in its axial direction. Preferably, the first shaft comprises a second cam such that on rotation of the first shaft, said second cam is rotated to abut one end of the second shaft and displace it in its axial direction away from the first shaft.

Preferably, the assembly further comprises seal means provided at a region of the interface between said first and second chambers, axial movement of the second shaft being configured to provide a releasable fluid tight seal between the first and second chambers. The seal means may be positioned at the second shaft, being moveable with the second shaft or alternatively the seal means may be secured in position in the region of the fluid passageway between the first and second chambers within the valve assembly housing.

Preferably, the assembly further comprises bias means configured to bias the second shaft in the axial direction in a direction towards the first chamber.

Preferably, the assembly comprises further bias means configured to bias the second shaft against rotation in the axial direction.

Preferably, the assembly further comprises a third shaft axially aligned with the first shaft and moveable in its axial direction. Further additional bias means may be provided to bias the third shaft into contact with the first shaft.

Optionally, lock means are provided to releaseably lock the first and third shafts in position to prevent their respective rotation.

According to a second aspect of the present invention there is provided a domestic or commercial central heating system comprising a valve assembly according to the present invention.

According to a third aspect of the present invention there is provided a method of controlling the supply of a fluid to a fluid circuit from a fluid supply source, said method comprising: introducing a fluid into a valve assembly through a supply inlet; allowing said fluid to flow from said inlet to a first chamber; preventing said fluid within said first chamber from flowing into a second chamber using chamber valve means; allowing any fluid present within said second chamber to drain from said second chamber via a drain outlet and drain valve means provided at said second chamber; closing said drain outlet via said drain valve means and opening said chamber valve means to allow fluid to flow from said inlet through said first and second chambers and from said valve assembly via a supply outlet

Brief Description of the Drawings

For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: Figure 1 illustrates a cross-sectional side elevation view of the valve assembly according to a first specific implementation; Figure 2 illustrates an external rear elevation view of the valve assembly of figure 1; Figure 3 illustrates a cross-sectional side elevation view of the valve assembly of figure 2; Figure 4 illustrates a cross-sectional side elevation view of the valve assembly of figure 3; Figure 5 illustrates a cross-sectional side elevation view of a valve assembly according to a further specific implementation of the present invention; Figure 6 illustrates a cross-sectional side elevation view of the valve assembly of figure 5; Figure 7 illustrates a cross-sectional side elevation view of the valve assembly of figure 6; Figure 8 illustrates a cross-sectional side elevation view of the valve assembly of figure 7; Figure 9 illustrates a cross-sectional side elevation view of the valve assembly of figure 8; Figure 10 illustrates a cross-sectional side elevation view of the valve assembly of figure 9; Figure 11 illustrates a cross-sectional side elevation view of the valve assembly of figure 10.

Detailed Description

There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to

unnecessarily obscure the description.

Figure 1 illustrates a cross-sectional side elevation view of the valve assembly 100 and figure 2 illustrates a rear elevation view of the valve assembly according to a first specific implementation. Referring to figure 1 and 2 the assembly comprises a first housing 117 defining a first chamber 103 and a second housing 116 defining a second chamber 104. Housings 117, 116 are removeably connected via a housing clip 121 slideably positioned within a recess formed within both housings 117, 116. An 0-ring seal 120 is positioned internally at the junction between first and second housings 117, 116 so as to provide a fluid-tight seal between first and second chamber 103, 104.

According to the substantially vertical alignment of the valve assembly 100 as illustrated in figure 1, first chamber 103 is positioned directly above second chamber 104, with both chambers being provided in fluid communication with one another via a respective opening or passageway in the lower portion of first housing 117 and an upper portion of second housing 116.

Upper housing 117 comprises an inlet extension 127 projecting substantially perpendicular to the main length of chamber 103. The substantially hollow inlet extension 127 comprises a first open end 101 configured to be connected to a mains water supply and a second end 126 being open and in fluid communication with first chamber 103. A first and second non-return valve 122, 123 are housed within inlet extension 127 and are separated by a non-return valve spacer 134.

Lower housing 116 similarly comprises a hollow outlet extension 128 extending substantially transverse to the substantially vertically aligned length of second chamber 104. Relative to the vertical alignment of first and second chambers 103, 104, outlet extension 128 is inclined to extend from an angle 500 80 from the vertical. Outlet extension 128 comprises a first open end 102 configured for connection to a primary circuit of a central heating system and a second open end 110 positioned in fluid communication with second chamber 104. As with inlet extension 127, two non-return valves 124, 125 are housed within outlet extension 128 separated by spacer 134. According to the specific implementation, inlet extension 127 is located immediately above outlet extension 128.

A vertically moveable shaft 108 is mounted to extend centrally through first chamber 103 and second chamber 104 within housings 117, 116, respectively. A suitable aperture 135 positioned at an uppermost region of first housing 117 enables shaft 108 to be moveably positioned within the housings. A first end of shaft 111 is positioned at a lowermost region of second chamber 104 whilst a second end of shaft 107 is mated with a solenoid 129 capable through activation to displace shaft 108 about its longitudinal axis and in the vertical direction through chambers 103, 104.

A main bobbin 136 is secured about a substantially central portion of shaft 108 and is secured in position by main bobbin circlips 119. A lowermost region of bobbin 136 is flanged 133 to prohibit the lowermost region of bobbin 133 from passing from second chamber 104 into first chamber 103. An 0-ring seal 105 is positioned at flange 133 configured to mate against an internal shoulder of second housing 116 to provide a fluid tight seal between the first and second chambers 103, 104 to prevent inter-chamber fluid communication.

Second chamber 104 is defined at its lowermost end by a housing cap 130 secured in position within the lowermost region of second housing 116. Housing cap 130 comprises a hollow central cavity 113 open in fluid communication with second chamber 104. A suitable 0-ring seal 131 is positioned between housing cap 130 and second housing 116 to provide a fluid-tight seal. Gauze 132 is positioned within housing cap 130 to extend across cavity 113.

A main bobbin bias spring 106 is positioned between bobbin flange 133 and the innermost surface of housing cap 130.

A second bobbin 115 is positioned at second end Ill of shaft 108 and is secured in position by appropriate circlips. A second bobbin bias spring 114 is positioned within second bobbin 115 to bias second bobbin 115 relative to shaft end 111.

A drain outlet seal 109 is positioned over and about the drain outlet extending through and about housing cap 130. A through-bore 112 extends through drain outlet seal 109 extending in fluid communication between second chamber 104 and drain cavity 113.

Additional seals (not shown) are also provided between shaft 108, aperture and solenoid 129 so as to prevent fluid from escaping from first chamber 103 during operation.

Figures 3 and 4 illustrate cross-sectional side elevation views of the valve assembly of figure 1 and 2 in a closed and open state, respectively.

Referring to figure 3, an air gap is created and maintained between the mains water supply connected at inlet 101 and the central heating circuit connected at outlet 102 via chamber 104 and an innermost region 110 of outlet extension 128. In the valve closed' state, water from the main supply 300 flows into the valve assembly via inlet 101 through non-return valves 122, 123 and into first chamber 103 via inlet 126. Shaft 108 is biased towards the solenoid end 129 by spring 106 referring to figure 1. With the shaft in this position, main bobbin flange 133 and 0-ring 105 are positioned in contact with second housing 116 to effectively isolate first chamber 103 from second chamber 104 from fluid communication. In this closed state, first chamber 103 is flooded with mains water whilst second chamber and region 110 of outlet extension 128 are substantially water-free providing an air gap between the mains water supply and the central heating system.

Additionally, with shaft 108 biased in the upward direction, shaft end 111 is provided in an non-contact position with drain outlet seal 109. In particular, through-bore 112 is open at both ends providing airflow communication between second chamber 104 and the drain outlet which is connected to a suitable drain or dirty water collection vessel. As shaft 108 does not press down on drain outlet seal 109, any water within second chamber 104 is capable of draining from the air gap out through the drain outlet.

Figure 4 illustrates the valve assembly in a valve open' state in which solenoid 129 is energised to displace shaft 108 in the downward direction against the return force of main bobbin spring 106 and second bobbin spring 114. In this valve open state, shaft end 111 is positioned in contact with drain outlet seal 109 to block through-bore 112 and close and seal the drain outlet between second housing 116 and housing cap 130. Accordingly, any fluid within chamber 104 and chamber 110 is prevented from flowing out of the valve assembly via the drain outlet.

The downward displacement of shaft 108 also displaces main bobbin 136, bobbin flange 133 and main bobbin seal 105 away from the interface between first chamber 103 and second chamber 104. This downward displacement of bobbin 136 creates a fluid flow passageway between first chamber 103 and second chamber 104. Mains water within chamber 103 can then flow to second chamber 104, chamber 110 and through non-return valves 125, 124 to be supplied to the central heating circuit as indicated by arrow 400.

From the valve closed to open state, the first operation is to close the drain outlet as shaft end 111 contacts drain outlet seal 109. Once a fluid tight seal has been secured at the drain outlet, the inter-chamber seal provided by 0-ring 105 and flange 133 is broken to allow liquid within first chamber 103 to flow into second chamber 104 and into the central heating system.

In the reverse direction from a valve open to valve closed state, the first operation is to close the inter-chamber valve via 0-ring seal 105 prior to the opening of the drain outlet valve via drain outlet seal 109. As solenoid 129 is de-energised, shaft 108 and main and second bobbins 136, 115 are forced in the upward direction by return springs 106, 114. Any hydraulic lock created by drain outlet seal 109 is released by air being bled into second chamber 104 via through-bore 112 as shaft end 111 is released from contact with drain outlet seal 109.

Figures 5 to 11 illustrate cross-sectional side elevation views of the valve assembly according to a further specific implementation 500. The assembly comprises a first housing 523 that defines a first chamber 521. A second housing 501 connected to first housing 523 defines a second chamber 522 provided in internal fluid communication with said first chamber 521 via passageway 524. Formed at the junction between first chamber 521 and second chamber 522.

A rotateable first shaft 505 extends centrally through second chamber 522 and is capable of rotation about its longitudinal axis within chamber 522. A second shaft 506 extends centrally through first chamber 521 and into a region of second chamber 522. Second shaft 506 is configured for movement in a direction parallel to its longitudinal axis such that a further end 516 of second shaft 506 is capable of projecting into and extracting from second chamber 522 via passageway 524.

Positioned at one end of second chamber 522 and first shaft 505 is a third shaft 520 coaxial and rotateably coupled to first shaft 505 via a shaft extension 507. Third shaft 520 is coaxial and rotateably coupled internally to a rotateable knob 517.

Third shaft 520 may be slideably disconnected from first shaft 505 via a disconnection with shaft extension 507 by movement in its axial direction. Third shaft 520 is maintained in indirect contact with first shaft 505 by a bias coil spring 508 positioned internally within housing 501 to abut, indirectly, against one end of third shaft 520.

s A further coil spring 511 is positioned towards one end of first shaft 505 configured to provide a return rotational force when first shaft 505 is rotated axially.

A drain outlet 502 is provided through first housing 501 so as to provide a fluid drain outlet from second chamber 522. A first cam 510 extends from the external surface of first shaft 505 in the region of drain outlet 502. A second cam 509 extending from the external surface of first shaft 505 is positioned at the region where second shaft 506 emerges into second chamber 522 towards contact with first shaft 505.

A coil spring 513 extends within first chamber 521 between first housing 523 and a flange 525 extending from one end of second shaft 506. Spring 513 is configured to bias second shaft 506 into contact with first shaft 505. A further coil spring 514 provides an additional bias force against second shaft 506 being positioned at one end of shaft 506 furthest from second chamber 522 and first shaft 505. A seal 512, typically an 0-ring seal, is positioned about second shaft 506 about the region of the internal fluid passageway 524 between first chamber 521 and second chamber 522. A further 0-ring seal 515 is provided substantially at the junction between slideably mounted third shaft 520 and one end of first shaft 505.

First housing 523 defines a supply inlet 503 suitable for coupling to a mains water supply pipe 526. Second housing 501 defines a supply outlet 504 also configured for coupling to water supply piping 527. Supply inlet 503 is provided in fluid communication with first chamber 521 whilst supply outlet 504 is provided in fluid communication with second chamber 522.

A locking mechanism 528 is provided at knob 517 configured to lock knob 517 in position to prevent axial rotation. Locking mechanism 528 comprises a shaft 518 configured to project into a co-operating groove 519 formed internally towards one end of rotatable knob 517.

In operation, with knob 517, third shaft 520 shaft extension 507 and first shaft 505 in a non-rotated position drain outlet 502 is open allowing any liquid within second chamber 522 to drain from the valve assembly 500. The operation of the valve assembly according to the further specific implementation will now be described with reference to figures 6 to 11.

Referring to figure 6, rotation 600 of knob 517 through 45 provides coupled axial rotation of third shaft 520, shaft extension 507 and the coupled first shaft 505. Cam 510 extending from the outer surface of first shaft 505 is also rotated and brought into contact with a flange 601 positioned internally within second chamber 522 at drain outlet 502. In this rotated position, cam 510 provides a fluid tight seal over and about the internal aperture of drain outlet 502 preventing fluid from flowing from second chamber 522 through drain outlet 502.

Referring to figure 7, further rotation 700 of knob 517 to provide a total rotation of approximately 180 provides further rotation of third shaft 520, first shaft 505 and cam 509. As cam 509 rotates it is brought into position towards inter-chamber passageway 524 and into contact with the end portion 516 of second shaft 506. This causes shaft 506 to be displaced along its longitudinal axis through first chamber 521 such that coil springs 513, 514 are compressed.

As shaft 516 is displaced away from passageway 524 so is seal 512. This allows fluid 701 to flow through supply inlet 503 through first chamber 521, inter-fluid passageway 524, and into second chamber 522. As the drain outlet is sealed by cam 510 fluid within second chamber 522 flows out of the valve assembly 702 and 703 via supply outlet 504. According to the configuration of figure 7, the valve assembly is configured to allow liquid, in particular water, within the central heating system to be topped-up' from the mains supply according to the manually controlledprocess of a user rotating knob 517 through the required angle.

Referring to figure 8, the valve assembly may be locked in the open position to allow fluid to flow from the mains supply into the central heating system. This is achieved by a sliding movement 800 of knob 517 towards and within second housing 501. When an end region 801 of knob 517 abuts internally against second housing 501 the moveable shaft 518 of locking mechanism 528 is depressed by a user 802 to engage with cooperating groove 519. This provides a rotateable lock for knob 517 and maintains valve assembly 500 in the open state.

Referring to figure 9, the valve assembly comprises a safety shut-off mechanism configured to prevent over pressurising of the central heating system by over-filling with water from the mains supply.

When the liquid pressure within second chamber 522 reaches a predetermined level of, for example 2 bar, third shaft 520 is displaced in the axial direction 900 away from first shaft 505. This pressure-forced movement of shaft 520 compresses coil spring 508 and releases locking mechanism 528 by dislodging shaft 518 from groove 519 in turn, forcing knob 517 axially away from second housing 501. With third shaft 520 held in the non-coupling position of figure 9, rotation of knob 517 does not provide coupled rotation of shaft extension 507 and importantly first shaft 505.

Referring to figure 10 as first shaft 505 is no longer held in position by knob 517, torsion spring 511 forces shaft 505 to rotate 1000 counter-clockwise to knob rotation 600, 700. Rotation of shaft 505 provides corresponding return rotation of cams 509, 510 releasing first shaft 505 and the seal provided at drain outlet 502.

Second shaft 506 is then displaced along its longitudinal axis 1002 by compression springs 513, 514 such that seal 512 is moved into position to provide a fluid-tight seal about passageway 524 and prevent fluid communication from first chamber 521 and second chamber 522. In this configuration water from the mains supply floods supply inlet 503 and first chamber 521, but is prevented from flowing further into the central heating system by the inter-chamber valve.

As the seal at the drain outlet is broken, liquid within second chamber 522 drains 1001 from the valve assembly. This creates an air gap at second chamber 522 between the mains supply connected at supply inlet 503 and the central heating system connected at supply outlet 504.

Back-flow of water from the central heating system into the valve assembly is prevented by at least one or a plurality of non-return valves (not shown) positioned at the supply outlet 504. Similarly, one or a plurality of non-return valves (not shown) are positioned at the supply inlet 503 to prevent back-flow of water from first chamber 521 into the mains supply.

Referring to figure 11, in response to the creation of the air gap within valve assembly 500 and a corresponding reduction in the internal pressure, shaft 520 is forced to return in the axial direction 1100 by coil spring 508 towards re-coupling with shaft extension 507. Accordingly, in the re-coupled position, rotation of knob 517 provides corresponding rotation of first shaft 505 and cams 510 and 509 such that knob 517 is returned to the control state of the valve assembly 500.

As will be appreciated by those skilled in the art, the valve assembly of the present invention provides variable fill rate functionality according to both the automated and manual control implementations. Additionally, both the automated and manual control valve assemblies are configured to provide an automatic shut-off of the valve in response to fluid pressure monitoring within the system to prevent over pressurising and in turn valve and system damage.

The present valve assemblies satisfy WRAS requirements due to the creation of an air gap between the supply inlet and supply outlet of the valve assembly corresponding to the mains water supply and the central heating system, respectively.

The valve assembly of the present invention is configured for releasable connection to the hydraulic component of both a domestic of commercial boiler, and in particular a combination boiler.

According to the specific implementations, as will be appreciated by those skilled in the art, should the valve assembly fail, the air gap within the second chamber is maintained until the assembly can be repaired. Accordingly, when the assembly is installed in position between the mains supply and the central heating system in an orientation rotated through 1800 as illustrated in figures 5 to 11, the air gap provided by the second chamber is positioned directly above the drain outlet to allow liquid draining from the device under gravity.

Claims

Claims: 1. A valve assembly configured to be positioned between a fluid

supply source and a fluid circuit, said valve assembly comprising: a supply inlet to allow fluid from said supply source to flow into said valve assembly; a first chamber, said supply inlet provided at said first chamber; a second chamber provided in fluid communication with said first chamber; chamber valve means operable to allow and prevent fluid communication between said first and second chambers; a drain outlet provided at said second chamber configured to allow fluid to drain from said chamber; a supply outlet to allow fluid from said supply source to flow out of said valve assembly, said supply outlet provided at said second chamber; and drain valve means operable to open and close said drain outlet.
2. The valve assembly as claimed in claim I wherein said chamber valve means and said drain valve means are operable such that said drain valve means is either opened or closed before said chamber valve means is opened or closed.
3. The valve assembly as claimed in claim 2 further comprising control means to control operation of said chamber valve means and said drain valve means.
4. The valve assembly as claimed in any preceding claim further comprising at least one non-return valve provided at said supply inlet.
5. The valve assembly as claimed in claim 4 comprising two non-return valves positioned at said supply inlet.
6. The valve assembly as claimed in any preceding claim comprising at least one non-return valve positioned at said supply outlet.
7. The valve assembly as claimed in claim 6 comprising two non-return valves positioned at said supply outlet.
8. The valve assembly as claimed in any preceding claim further comprising a moveable shaft extending though said first and second chambers, said shaft moveable in its axial direction.
9. The valve assembly as claimed in claim 8 further comprising first seal means positioned at the region of the interlace between said first and second chambers wherein movement of said shaft in its axial direction serves to open and close fluid communication between said chambers.
10. The valve assembly as claimed in claim 9 further comprising second seal means positioned towards one end of said shaft at said drain outlet wherein movement of said shaft provides movement of said second seal means in the axial direction of said shaft to open and close said drain outlet.
11. The valve assembly as claimed in any one of claim 8 to 10 further comprising an actuator connected towards a second end of said shaft, said actuator configured to move said shaft in said axial direction.
12. The valve assembly as claimed in claim 11 wherein said actuator comprises a solenoid.
13. The valve assembly as claimed in claim 10 wherein said second seal means comprises a through-bore providing a fluid passageway through said second seal means between said second chamber and a region external to said second chamber.
14. The valve assembly as claimed in any one of claims 11 to 13 further comprising bias means to bias said shaft in its axial direction opposed to said direction of movement provided by said actuator.
15. The valve assembly as claimed in claim 14 wherein said bias means comprises at least one spring.
16. The valve assembly as claimed in any one of claim 1 to 7 further comprising a first shaft extending through said second chamber, said first shaft being rotateable about its longitudinal axis.
17. The valve assembly as claimed in claim 16 wherein said first shaft comprises a first cam, such that on rotation of said first shaft said cam is configured to releaseably open and close said drain outlet.
18. The valve assembly as claimed in claim 17 further comprising a second shaft aligned substantially transverse to said first shaft positioned to extend through a part of said first and second chambers, said second shaft configured to move in its axial direction.
19. The valve assembly as claimed in claim 18 wherein said first shaft comprises a second cam wherein on rotation of said first shaft said second cam is configured to abut one end of said second shaft and displace said second shaft in said axial direction.
20. The valve assembly as claimed in claim 19 further comprising seal means provided at a region of the interface between said first and second chambers, axial movement of said second shaft configured to provide a releaseable fluid tight seal between said first and second chambers.
21. The valve assembly as claimed in claim 20 further comprising bias means configured to bias said second shaft in the axial direction into said first chamber.
22. The valve assembly as claimed in claim 21 comprising further bias means configured to bias said first shaft against said axial rotation.
23. The valve assembly as claimed in claim 21 or 22 wherein said bias means comprises at least one spring.
24. The valve assembly as claimed in claim 23 further comprising a third shaft axially aligned with said first shaft and moveable in the axial direction; and further bias means to bias said third shaft into contact with said first shaft.
25. The valve assembly as claimed in claim 24 further comprising a knob positioned at one end of said third shaft to enable a user to rotate said first and third shafts by rotation of said knob.
26. The valve assembly as claimed in any one of cLaims 16 to 25 further comprising lock means to releaseably lock said first shaft in position to prevent rotation.
27. A domestic central heating system comprising a valve assembly according to any preceding claim.
28. A commercial central heating system comprising a valve assembly as claimed in any one of claims 1 to 26.
29. A method of controlling the supply of a fluid to a fluid circuit from a fluid supply source, said method comprising: introducing a fluid into a valve assembly through a supply inlet; allowing said fluid to flow from said inlet to a first chamber; preventing said fluid within said first chamber from flowing into a second chamber using chamber valve means; allowing any fluid present within said second chamber to drain from said second chamber via a drain outlet and drain valve means provided at said second chamber; closing said drain outlet via said drain valve means and opening said chamber valve means to allow fluid to flow from said inlet through said first and second chambers and from said valve assembly via a supply outlet.