Flush valve apparatus

Abstract

A flush valve 100 including a central tube 10 having a first end 12 securable to a flush valve seat and a flush opening (e.g. slots 18 Fig. 2) located towards the first end of the tube for allowing wa

Description

The present invention relates to a toilet flush valve apparatus for use with, for example, a toilet system comprising a push button toilet flush. A toilet flush mechanism comprises several parts where, over time, one or more of these parts may become faulty. Existing methods for repairing a toilet flush mechanism often require the replacement of several parts where only one of those may be faulty. This is, at least in part, because existing parts of a toilet flush mechanism produced by one manufacturer are generally not compatible with the parts produced by a different manufacturer. For example, a toilet flush valve seat generally connects and supports a toilet flush valve apparatus to a flush outlet hole in the toilet cistern, the hole fluidly connected to the toilet bowl. The flush valve apparatus is arranged to provide a volume of water to pass through the flush valve seat to the toilet bowl, when the toilet flushing mechanism is operated. A flush valve seat made by one manufacturer typically has a bayonet style mount fitting, whereby it comprises a cage portion having a slot or recess with a precise size and shape for receiving a corresponding pin (having a matching size and shape) located on a matching flush valve apparatus produced by the same manufacturer. The slot on the cage portion of the flush valve seat will typically be shaped such that a flush valve apparatus produced by a different manufacturer will not be compatible. Consequently, if the flush valve apparatus is faulty, both the flush valve seat and flush valve apparatus may need replacing, which can be time consuming and can also be a waste of the non-faulty part. Due to the fiddly nature of the existing systems, people generally require a plumber to repair the toilet system. Existing flush valve apparatus are generally designed to fit either a flush valve seat having a 2 inch diameter or a flush valve seat having a 1.5 inch diameter. The diameter refers to the internal pipe diameter of the flush valve seat. US 2009 / 0025130 Al describes a flush valve for flushing a toilet bowl. The flush valve includes a centre tube having a lug, a flush activation device configured to initially raise the centre tube, at least one latching mechanism configured to control movement of the centre tube, and at least one rack configured to have movement controlled by the at least one latching mechanism. The at least one latching mechanism controls volume of fluid used during a flush. The present invention seeks to provide a flush valve apparatus which is user-friendly, and which is simple to install. The present invention also seeks to provide a flush valve apparatus that is compatible with a variety of flush valve seats. According to a first aspect of the present invention there is provided a flush valve apparatus comprising: a central tube having a first end configured to be securable to a flush valve seat, and a flush opening located in a sidewall of the central tube towards the first end for allowing water to pass through the sidewall into a central lumen of the central tube, an outer tube slidably moveable over the central tube, the outer tube having a sealing end for sealing with the flush valve seat, wherein in a closed position, the sealing end creates a watertight seal with the flush valve seat and the outer tube prevents fluid ingress via the flush opening to the central lumen. In this way, the present invention provides a flush valve apparatus that has a relatively simple design and is simple to install into an existing flush valve seat fitted within a toilet cistern. The apparatus is suitable for retrofitting to existing toilet cisterns having, for example, an existing toilet flush valve seat. The flush valve apparatus of the invention can be installed with many existing flush valve seats. The simple design of the apparatus provides a flush valve which is slim and compact to assist in straight forward installation. The simple design also has the advantage of having fewer parts making it more durable. Preferably, the central tube is also an overflow tube. In this way, the apparatus permits overflow water within the toilet cistern to enter into the central lumen of the central tube and then pass into the toilet bowl. As the apparatus itself provides an overflow tube, this allows the apparatus to be fit into any existing flush valve seat, which may or may not have an existing overflow tube. Conveniently, the first end of the central tube is configured to be securable to the flush valve seat in a push-fit manner. The apparatus can thus be installed in an easy and user-friendly way without requiring tools or complicated fittings. The push-fit fitting provides a sturdy and secure fixture to the flush valve seat. Preferably, the first end of the central tube is configured to be securable to an internal pipe of the flush valve seat. In this way, the apparatus can be secured to various different types of flush valve seats, regardless of any existing bayonet style fittings that they may already have. This ensure that the apparatus is easy to retrofit. Conveniently, in an open position the sealing end is disengaged from the flush valve seat to thereby allow water to flow via the flush opening to the central lumen of the central tube. Preferably, operation of a flush activator causes the outer tube to slidably move along the longitudinal axis of the central tube, thereby moving the apparatus from the closed position to an open position. Conveniently, the central tube comprises multiple flush openings. Preferably, there are at least two flush openings in the central overflow tube. In this way, upon flushing the toilet water can flow from the toilet cistern into the central lumen of the central tube via a number of different openings. This ensures that enough water enters the toilet bowl. Preferably, the central tube comprises overflow openings located in the sidewall of the central tube towards a second end, wherein the second end is opposite the first end. The overflow openings allow water to pass through the sidewall of the central tube. In this way, the apparatus permits overflow water within the toilet cistern to enter the central lumen of the central tube and fluidly pass into the toilet bowl. In particular, when the water level reaches above the outer tube, water will flow into the overflow openings. As the apparatus itself provides overflow openings, this allows the apparatus to be fit into any existing flush valve seat, which may or may not have an existing overflow tube. Conveniently, the sealing end comprises a sealing ring. In this way, the apparatus provides a simple and straightforward mechanism for creating the watertight seal with the flush valve seat. In addition, should the sealing ring of the apparatus become faulty or damaged through wear and tear it would be easy to replace. Preferably, the central tube comprises a bung at the first end for securing the apparatus within the flush valve seat. Preferably, the bung secures the apparatus within the flush valve seat in a fluidly sealed manner. In this way, the apparatus of the invention is user-friendly and easy to install with the flush valve seat. By using a bung, the apparatus attaches to the flush valve seat in a simple, push-fit manner which provides a firm fit to the internal pipe of the flush valve seat. In this way, the invention avoids the bayonet style attachments to the cage portion of the flush valve seats which is typically seen in the flush valve apparatus of the prior art. Preferably, the bung is composed of a deformable material. An example of a suitable deformable material is foam rubber, which provides a firm fitting to the flush valve seat. Conveniently, the central tube has a second end opposite the first end, wherein the second end and the outer tube are both configured for attachment to a flush activator. In this way, the apparatus can be attached to an existing flush activator, such as a push-button flush mechanism. Preferably, the second end of the central tube comprises a cap having a guide for attaching to the flush activator. Preferably the cap is removable from the central tube. This relatively simple attachment to the flush activator makes installing the apparatus user-friendly. Conveniently, the outer tube comprises a float for assisting the buoyancy of the outer tube. In this way, the float ensures that upon the toilet being flushed the outer tube is lifted up above the water line such that it no longer blocks or partially blocks the flush opening to allow water to enter therethrough. This ensures that an adequate amount of water is able to flow through the flush opening and fill the toilet bowl to the desired level. Conveniently, the apparatus further comprises an adaptor attached to the first end of the central tube. In this way, the invention is able to fit to flush valve seats having a greater variety of internal pipe diameters. For example, the adaptor may be used when the apparatus is attached to a flush valve seat having an internal pipe diameter of 1.5 inches. In embodiments where the adaptor is used with the apparatus, the bung is attached to the adaptor. Preferably, the apparatus is suitable for use with a 1.5 inch flush valve seat or a 2 inch flush valve seat. Most common current existing flush valve seats have an internal diameter of either 1.5 inches or 2 inches. The apparatus of the invention is designed to fit into either of these, as well as other sized flush valve seats. Conveniently, the apparatus further comprises a guide system for aligning the central tube and the outer tube together. In this way, the apparatus prevents unwanted rotation of the outer tube relative to central tube. Preferably, the guide system comprises a ribbed portion on the central overflow tube and a corresponding recessed portion on the outer tube, or vice versa. This provides the invention with a simple, easy to use and manufacture way for preventing unwanted rotation of the outer tube relative to the central tube. According to a second aspect of the present invention there is provided a kit of parts comprising the apparatus according to the invention. According to a third aspect of the present invention there is provided a method of installing the flush valve apparatus according to the invention, the method comprising: placing the central tube within a flush valve seat; and attaching the outer tube to a flush activator. In this way, the invention provides an easy and straightforward method for installing a new flush valve apparatus. Due to the push-fit nature of the attachment between the apparatus of the invention and the internal pipe of a flush valve seat, installing the apparatus of the invention is typically easier compared to existing toilet flush apparatus which generally require a bayonet style fitting to the cradle / basket portion of the flush valve seat. The attachment of the apparatus to a flush activator is also designed to be user-friendly. The apparatus can be used with an existing flush activator. According to a fourth aspect of the present invention there is provided a method of flushing a toilet using the flush valve apparatus according to the invention. Features of the first aspect of the invention may be used with the second, third or fourth aspects of the invention. The above and other aspect of the present invention will now be described in further detail, by way of example only, with reference to the accompanying Figures, in which: Figure 1 shows a front view of the apparatus of the present invention Figure 2 shows an exploded view of the apparatus according to the present invention Figure 3 shows a cross section of the apparatus of the present invention Figure 4 shows the apparatus of the present invention in a first, closed position in a toilet cistern Figure 5 shows the apparatus of the present invention in a second, open position in a toilet cistern Figure 1 shows a front view of flush valve apparatus 100. The apparatus 100 comprises a central overflow tube 10 and an outer tube 30. The apparatus is shown attached to a push button flush activator 300. The central overflow tube 10 has a first end 12, a second end 14 and a sidewall 16 extending therebetween. The central overflow tube 10 has a lumen 15. The sidewall 16 of the central overflow tube 10 has overflow openings 17 and flush openings 18, as shown in Figure 2. The overflow openings 17 provide a fluid opening into lumen 15 for water overflow. Water flowing into lumen 15 will flow into a toilet bowl associated with the cistern in which the apparatus is installed. As shown, the overflow openings 17 are located towards the second end 14 (which in use is the top) of the central overflow tube, in this way water will only flow into the overflow openings 17 when the water level reaches the height of the overflow openings 17 and is above the height of the outer tube 30. In the illustrated embodiment several overflow openings 17 are shown, however the number of overflow openings 17 may vary. For example, it is possible that there may be fewer or a greater number of overflow openings than those depicted. It is also possible that the size and shape of the overflow opening / s may vary. For example, the illustrated embodiment shows oval openings, however the opening / s may be any suitable shape, providing that water is able to flow through the overflow openings 17 into lumen 15, to thereby avoid water overflow. The overflow openings 17 should therefore allow an adequate volume of water to flow therethrough. The flush openings 18 of the central tube 10 shown in Figures 2 and 3 provide fluid openings into lumen 15 for water to be flushed into the toilet bowl. As shown, the flush openings 18 are located towards the first end 12 of the central overflow tube 10, i.e., the opposite end from the overflow openings 17. While the illustrated embodiment shows four flush openings 18 it is possible that there may be a single opening or more than two openings. It is also possible that the size and shape of the opening / s may vary. For example, the illustrated embodiment shows oval openings, however the opening / s may be any suitable shape, providing that upon operating the flush activator 300 an adequate amount of water is able to flow through the flush openings 18 into lumen 15 to flush the toilet. The flush openings 18 should therefore allow an adequate volume of water to flow therethrough. The central tube 10 also has a removable bung 20 attached to the end of the first end 12. In the embodiments shown, the bung 20 is push-fit on to the central overflow tube 10. As shown in Figures 4 and 5 (discussed in greater detail below), the bung 20 is tapered and secures the central overflow tube 10, and consequently the entire apparatus 100, to the flush valve seat 50 by securing to the internal pipe 52 of the flush valve seat in a push-fit manner. Thus, the outer diameter of the bung 20 (at its widest part) is sized to fit securely within the internal pipe 52 of a flush valve seat 50, preferably in a fluidly sealed manner. The material of the bung 20 is resilient to thereby assist in its fitting and its tapered shape makes it easier to fit securely within the flush valve seat. In the illustrated embodiment, the bung is positioned on the central tube such that the top of the bung 20 is adjacent the bottom of the flush openings 18. The bung 20 preferably has a lip (not shown) facing inwards at its lower end to prevent the bung 20 moving up the central overflow tube 10. Bungs having different outer dimensions can be fitted to the central tube 10 to enable the apparatus to fit within different sized flush valve seats. The dimensions of the bung 20 may therefore vary depending on the dimensions of the internal pipe 52 of the flush valve seat 50 to which it is to be secured. For example, if the toilet cistern is fitted with a working flush valve seat having an internal pipe diameter of 2 inches, then a bung having an outer diameter designed to fit a pipe of 2 inches can be used. As the bung 20 secures the apparatus 100 in place, it should fit tightly and securely within the flush valve seat 50. The flush valve apparatus 100 may also comprise a removable adapter (not shown) to allow the apparatus to fit within different sized toilet flush valves. The removable adaptor is an additional tubular portion that can be fitted to the end of first end 12 of the central tube 10. Preferably, the removable adapter 24 has a threaded portion for securing to a corresponding threaded portion on the first end 12. The adaptor preferably has a smaller diameter compared to the diameter of the central tube 10, such that a smaller bung can be fitted thereto. In this way, the removable adapter enables the apparatus 100 to fit to a wider variety of different sized flush valve seats. As shown in the Figures, the central overflow tube 10 is open at the second end 14 to permit water to flow over the second end 14 into the lumen 15 and into the toilet bowl. In this way, the apparatus provides another path for overflow water (in addition to that provided by the overflow openings 17). The second end 14 of the central overflow tube 10, which is opposite the first end 12, comprises a removeable cap 25. The cap 25 has a short tubular portion which is shaped to fit over the second end 14. The top of the cap 25 is open such that it does not cover or block the lumen 15 of the central overflow tube 10, to thereby still allow excess water to flow over the second end 14 of the central overflow tube 10 into the lumen 15. An inner lip (not shown) is provided on the inside of the cap 25 to prevent the cap 25 moving along the longitudinal length of the central overflow tube. The removable cap 25 has a first cable guide portion 26 extending outwards from the tubular portion for attaching to a cable 60 of the flush activator mechanism 300. The first cable guide portion 26 of the cap 25 is aligned with a second cable guide portion 45 on the outer tube 30, which is explained in greater detail below. In addition to providing guidance for a flush activator, the cap 25 restricts the slidable movement of the outer tube 30 along the longitudinal axis of the central overflow tube 10 by preventing the outer tube 30 from moving past the second end 14 of the central tube 10. In the illustrated embodiment, the first cable guide portion 26 comprises two cable holding plates 27a, 27b for securely guiding the cable of the flush activator. The cable holding plates extend outwardly from the removable cap 25 and are aligned and parallel to one another and. While the illustrated embodiment shows two cable holding plates 27a, 27b the number of holding plates may vary. For example, there may be a single cable holding plate or more than two cable holding plates providing that the cable holding plate / s securely guide the cable of a flush activator. Alternatively, the guide portion may take another form other than cable holding plates. As shown in Figures 1 and 2, the outer tube 30 has a sealing end 32, a second end 34 and a sidewall 36 extending therebetween. The outer tube 30 has lumen 35. A sealing ring 38 is located at the end of the sealing end 32 of the outer tube 30 which, in use, forms a watertight seal with a flush valve seat (depicted in Figures 4 and 5). Situated above the sealing ring 38 is a float 40. The float 40 helps to keep the outer tube 30 up to the water line during the flushing process. The float 40 is preferably a foam outer washer. In the illustrated embodiments a raised rim 41 is provided on the outer tube 30 to stop the float 40 sliding along the longitudinal axis of the outer tube 30. While the illustrated embodiment depicts a raised rim 41, the float 40 can be secured in place using any suitable means. Located above the float 40 and raised rim 41 is a second cable guide portion 45 which extends outwardly from the sidewall 36. The second cable guide portion 45 is configured such that the cable 60 of the flush activator can be thread therethrough. As shown in Figures 1 and 3 for example, the second cable guide portion 45 is aligned with the first cable guide portion 26 of the removable cap, such that it sits beneath the guide portion 26. This prevents any slack in the cable 60. The second cable guide portion 45 couples the outer tube 30 to the end of the same cable 60 attached to the cap 25. In the embodiment shown, the second cable guide portion 45 comprises a small tubular portion having a longitudinal axis which is parallel to the longitudinal axis of the central and outer tubes. At the end of the cable 60 is a ball, such that diameter of the end of the second cable guide portion 45 is smaller than the diameter of the cable 60. When the flush 300 is operated (e.g. by a user pushing the flush button), this causes the cable 60 to shorten. Due to the second cable guide portion 45 being smaller than the end of the cable, the end of the cable is forced against the second cable guide portion 45, driving the outer tube 30 upwards along the longitudinal axis of the central tube 10. As a result, the seal between the sealing ring 38 and the flush valve seat 50 is broken, thereby allowing water in the toilet cistern to flow therethrough. As shown in the Figures, the central overflow tube 10 and the outer tube 30 are co-axial. Accordingly, the inner diameter of the outer tube 30 is slightly larger than the outer diameter of the central overflow tube 10, such that the outer tube 30 can slide easily over the central overflow tube 10. Both the central overflow tube 10 and outer tube 30 have a substantially elongate configuration. In use, the outer tube 30 is slidably connected to the central overflow tube 10 such that they share the same longitudinal axis. As depicted, the outer tube 30 has a shorter longitudinal length compared to that of the central overflow tube 10 to enable the outer tube 30 to slide along the longitudinal length of the central overflow tube, without extending above or below it. The cap 25 prevents the outer tube 30 sliding past the second end 14 of the central overflow tube 10 off the central overflow tube 10. The second cable guide portion 45 also has longitudinal axis which, as mentioned, is parallel to the longitudinal axis of the central and outer tubes. While the illustrated embodiments show components having a generally circular cross section, the components may have any suitable shaped cross section. Figure 4 shows the flush valve apparatus of the present invention in a first, closed position. In this closed position, the flush openings 18 of the central overflow tube 10 are occluded such that water surrounding the apparatus cannot flow through the flush openings. In use, the bung 20 is secured in place within the internal pipe 52 of the flush valve seat 50 and the sealing ring 38 forms a watertight seal with the base portion 54 of the flush valve seat 50. Thus, in the closed position water in a toilet cistern is prevented from flowing through the flush openings 18 by the outer tube 30 blocking the flush openings and the watertight seal between the sealing ring 38 and the flush valve seat 50. In this way, when the flush valve apparatus is installed in a toilet cistern, water is held within the cistern when the flush valve apparatus is in the closed position. As shown in Figures 4 and 5, existing flush valve seats 50 typically have a cage portion 56, a base portion 54 and an internal pipe 52 extending therefrom. The cage portion 56 and the base portion 54 of the flush valve seat sit in the toilet cistern, while the internal pipe 52 extends through an outlet flush hole in the toilet cistern 200 to fluidly connected the cistern to an adjacent toilet bowl (not shown). The water level within the cistern is normally controlled by a toilet fill valve (not shown) such that the toilet fill valve stops water entering the cistern once a predetermined amount or level of water is held within the tank. However, in case this system fails, an overflow tube is typically installed which enables excess water in the cistern to flow through the overflow tube and into the toilet bowl and thereby prevent the cistern overfilling and / or flooding. The central overflow tube 10 of the present invention provides this overflow system. Thus, even if the flush valve apparatus is in the closed position, if the water level reaches the overflow openings 17, the water will flow through the overflow openings 17 into the lumen 15 of the central overflow tube 10 and into the toilet bowl. As the second end of the central tube 10 is open, this also provides another path for water to flow through, should the water reach the top of the central tube. Figure 5 shows the flush valve apparatus of the present invention in a second, open position. In the open position, the outer tube 30 is above the flush openings 18 of the central overflow tube 10 and the sealing ring 38 is above the base 54 and therefore no longer forms a watertight seal with the flush valve seat 50. Thus, in the open position water surrounding the flush valve apparatus is free to flow from within the cistern through the flush openings 18 into the lumen 15 of the central overflow tube 10 and into the toilet bowl. In use, the flush valve apparatus of the present invention is moved from the closed position to the open position upon activation of a flush activator 300. In Figures 4 and 5, the flush activator 300 is shown as a push button flush mechanism. As described, upon operation of the flush activator 300, the cable 60 temporarily shortens, causing the end of the cable 60 to pull upwards and as a result the outer tube 30 is slidably pulled up along the longitudinal axis of the central overflow tube 10. This releases the watertight seal between the sealing ring 38 and the flush valve seat 50 and at least partially reveals the openings. The float 40 holds the outer tube 30 up to the water line. The central tube 10 does not move during the flushing cycle as it is held in place in the flush valve seat 50 by bung 20. While the illustrated embodiments depict a push button toilet flushing mechanism, the apparatus can be used with any suitable toilet flushing mechanism. Once the flush activator 300 is released and the water has emptied from the cistern, the outer tube 30 is no longer held up by flush activator 300 or the float 40, and so the outer tube 30 will fall back into the closed position due to gravity, reforming the watertight seal between the sealing ring 38 and the base 54 of the flush valve seat 50 and blocking the openings 18. A toilet refill / inlet valve (not shown) allows water to enter the cistern and refill, ready for the next flush activation. The water volume can be controlled in this instance by the toilet inlet valve. In the illustrated embodiments shown in Figures 1 and 2, the flush valve apparatus 100 is provided with a guide system to ensure that the components of the apparatus are aligned correctly. In particular, the central overflow tube 10 comprise rib 29 (an identical rib is also located on the opposite side of the central overflow tube 10 but cannot be seen in the Figures). The ribs 29 are a continuous line from the second end 14 to around halfway along the longitudinal length of the central overflow tube 10. The outer tube 30 is provided with corresponding recesses 39 to accommodate the ribs 29, such that the outer tube 30 slides easily along the longitudinal length of the central overflow tube. The removable cap 25 is also provided with corresponding recesses (not shown) to accommodate the ribs 29 on the central overflow tube 10. The guide system prevents unwanted clockwise or anticlockwise turning of the central overflow tube, outer tube or the cap 25 relative to one another. This is for maintaining alignment of the second cable guide portion 45 (located on the outer tube 30) and the first cable guide portion 26, including cable holding plates 27a, 27b (located on the central overflow tube 10). The first and second cable guide portions should be aligned so that the length of the cable 60 is consistent between flushes for consistent and efficient flushing. While the illustrated embodiment shows a guide system comprising two ribs and two corresponding recesses, any suitable guide system may be used which prevents unwanted clockwise or anticlockwise movements between the components. It is possible, for example, that the central overflow tube may comprise only one rib, with the outer tube and cap having only one corresponding recess each. In addition, while the illustrated embodiment shows the central overflow tube comprising ribs and the outer tube and cap having corresponding recesses, this could also be the other way round whereby the outer tube has ribs and the central overflow tube comprises the recess. In addition, while the illustrated embodiment shows a guide system comprising ribs and recesses, other means of aligning the components of the flush valve apparatus are also possible. To install the flush valve apparatus of the present invention into a toilet cistern, the central tube is simply pushed into the internal pipe of a flush valve seat. The cable of a flush activator is then thread through the second cable guide portion (the ball portion may need to be detached from the cable and then reattached once thread through) and then attached to the first cable guide portion. Thus, in contrast to the prior art, the toilet flush valve apparatus of the present invention secures in a push-fit manner to the internal pipe of the flush valve seat. Kits of the present invention comprise the components of the flush valve apparatus described herein. Preferably, kits of the invention comprise two different sized bungs for fitting within different sized flush valve seats. In this way, kits of the invention can be easily applied to a variety of different existing flush valve seats. While exemplary materials are described herein, it will be appreciated that any suitable materials may be used for the features of the apparatus providing that the features are able to carry out their primary functions, as detailed herein. The flush valve apparatus is preferably composed of a material, such as plastic, which is relatively inexpensive, durable and resistant to corrosion. The material of the central overflow tube 10 and the outer tube 30 is preferably one which can be easily cut to size, for example using a hacksaw. In this way, the apparatus can be easily adapted to fit a variety of different toilet systems. The bung 20 may be composed of foam rubber, as this enables the bung to be easily but firmly fitted (by simply pushing) within the internal pipe of the flush valve seat. The float 40 may be composed of foam and the sealing ring 38 may be composed of silicone. While exemplary dimensions are described herein, it will be appreciated that any suitable dimensions may be used for these features of the apparatus providing that the features are able to carry out their primary functions, as detailed herein. In an exemplary embodiment, the central overflow tube has a longitudinal length of approximately 250 mm and the outer tube has a longitudinal length of approximately 168 mm. The diameter of the lumen of the central overflow tube is approximately 28 mm and the diameter of the lumen of the outer tube is approximately 34 mm. The sealing ring has an outer diameter of approximately 66 mm. The flush valve apparatus of the present invention is designed for use in standard toilet systems. In particular, the apparatus is designed to fit flush valve seats having an internal pipe diameter of around 1.5 inches or 2 inches.

Claims

1. A flush valve apparatus comprising:a central tube havinga first end configured to be securable to a flush valve seat, anda flush opening located in a sidewall of the central tube towards the first end for allowing water to pass through the sidewall into a central lumen of the central tube, an outer tube slidably moveable over the central tube, the outer tube havinga sealing end for sealing with the flush valve seat,wherein in a closed position, the sealing end creates a watertight seal with the flush valve seat and the outer tube prevents fluid ingress via the flush opening to the central lumen.

2. The apparatus according to claim 1, wherein the central tube is an overflow tube.

3. The apparatus according to claim 1 or claim 2, wherein the first end of the central tube isconfigured to be securable to the flush valve seat in a push-fit manner.

4. The apparatus according to any one of the preceding claims, wherein the first end of the central tube is configured to be securable to an internal pipe of the flush valve seat.

5. The apparatus according to any one of the preceding claims, wherein in an open position the sealing end is disengaged from the flush valve seat to thereby allow water to flow via the flush opening to the central lumen of the central tube.

6. The apparatus according to claim 5, wherein activation of a flush activator causes the outer tube to slidably move along the longitudinal axis of the central tube, thereby moving the apparatus from the closed position to an open position.

7. The apparatus according to any one of the preceding claims, wherein there are at least two flush openings in the central tube.

8. The apparatus according to any one of the preceding claims, wherein there are multiple flush opening in the central tube.

9. The apparatus according to any one of the preceding claims, wherein the central tube comprises an overflow opening located in the sidewall of the central tube towards a second end, wherein the second end is opposite the first end.

10. The apparatus according to claim 9, wherein there are multiple overflow openings.

11. The apparatus according to any one of the preceding claims, wherein in use the central tubeis fixed in place such that it does not move during a flushing cycle.

12. The apparatus according to any one of the preceding claims, wherein the central tube comprises a bung at the first end for securing the apparatus within the flush valve seat.

13. The apparatus according to claim 12, wherein the bung is composed of a resilient material.

14. The apparatus according to any one of the preceding claims, wherein the central tube has asecond end opposite the first end, wherein both the second end and the outer tube are configured for attachment to a flush activator mechanism.

15. The apparatus according to claim 14, wherein the second end comprises a cap having a first cable guide portion and the outer tube comprises a second cable guide portion wherein each of the first cable guide portion and the second cable guide portion is for attaching to the flush activator mechanism.

16. The apparatus according to any one of the preceding claims, wherein the outer tube comprises a float for assisting the buoyancy of the outer tube.

17. The apparatus according to any one of the preceding claims, wherein the apparatus further comprises an adaptor attached to the first end of the central tube.

18. The apparatus according to any one of the preceding claims, wherein the apparatus further comprises a guide system for aligning the central tube and the outer tube together to prevent unwanted rotation relative to one another.

19. The apparatus according to claim 18, wherein the guide system comprises a ribbed portion on the central tube and a corresponding recessed portion on the outer tube, or vice versa.

20. A kit of parts comprising the apparatus according to any one of claims 1 to 19.

521. A method of installing the flush valve apparatus according to any one of claims 1 to 19, the method comprising:securing the central tube within the flush valve seat; andattaching the central tube and the outer tube to a flush activator.1022. A method of flushing a toilet using the flush valve apparatus according to any one of claims 1 to 19.15

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