Water closet

Abstract

A cistern assembly, including a mount, of an air-assisted water closet, the mount comprising a first generally planar portion arranged in a first plane, the first portion having a front side, a rear side opposite the front side, and one or more first mounting features for fixing the rear side to a wall; one or more second mounting features for mounting a water tank to the mount; and one or more third mounting features for mounting an air pump to the mount.Figure 3

Description

WATER CLOSET  FieldThe present disclosure relates to components for use in an air-assisted water closet, assemblies thereof, and to operating methods associated with such components and assemblies. BackgroundAir-assisted water closets exist which, in addition to water, use air pressure to assist with the flushing of waste from a waste pan of said water closet, into a drainage system of a building. Previous designs of air-assisted water closets, and associated operating methods, have proved successful but not entirely optimal. The present disclosure aims to alleviate, at least to an extent, problems associated with existing air-assisted water closets. SummaryAccording to a first aspect of the present disclosure there is provided a mount for a cistern assembly of an air-assisted water closet, the mount comprising:a first generally planar portion arranged in a first plane, the first portion having a front side, a rear side opposite the front side, and one or more first mounting features for fixing the rear side to a wall;one or more second mounting features for mounting a water tank to the mount; and one or more third mounting features for mounting an air pump to the mount.Optionally, the one or more first mounting features comprise at least one slot configured to receive at least two screws to support a weight of the mount. Optionally, the one or more first mounting features further comprise apertures configured to receive screws for fixing the rear side to a wall. Optionally, the one or more first mounting features are positioned relative to both the one or more second mounting features and the one or more third mounting features such that the one or more first mounting features are outside an area of the mount that is covered by the water tank and the air pump when they are mounted to the mount.Optionally, the mount further comprises a second generally planar portion arranged in a second plane, the second plane being parallel to and spaced apart from the first plane in a direction away from the rear side and towards the front side, wherein the second portion comprises an opening therethrough for air to pass through, and wherein the third mounting features and the opening are arranged relative to each other such that when an air pump is mounted to the second portion using the third mounting features, the opening is arranged to admit air to at least a portion of the air pump. Thus, in one or more examples, the second generally planar portion comprises a part of the mount configured to be spaced away from a wall upon which the mount is fixed.Optionally, the second portion further comprises one or more alignment features for aligning a cover of said air pump with the second portion when said air pump is mounted to the second portion.Optionally, the one or more second mounting features comprise at least one protrusion arranged for engagement with a corresponding recess of a corresponding water tank, and / or at least one recess arranged for engagement with a corresponding protrusion of said corresponding water tank.According to a second aspect of the present disclosure there is provided a cistern assembly comprising the mount of any preceding claim, and comprising at least one of a corresponding air pump and a corresponding water tank, arranged for mounting to the mount.Optionally, the cistern assembly comprises said air pump, wherein the air pump is a centrifugal type, vane pump type or any other type.Optionally, the cistern assembly comprises said air pump, wherein the air pump comprises an electric motor, a cover, and noise reducing material provided between the motor and the cover, wherein optionally the noise reducing material comprises a foam material.Optionally, the cistern assembly comprises said air pump, wherein the air pump comprises a pump body and an electric pump motor, wherein the pump motor is attached to the pump body via a number of vibration insulators. According to a third aspect of the present disclosure there is provided a subframe component of a water tank assembly of an air-assisted water closet, said subframe component being arranged to be removably mountable inside a water tank of said water tank assembly, by virtue of the subframe component comprising an engagement portion for removable engagement with said water tank, wherein said subframe component is provided with respective attachment positions for a plurality of further components of said water tank assembly.Optionally, the subframe component comprises two or more of: a first attachment position for attaching a water inlet valve, such as a solenoid water inlet valve; a second attachment position for attaching a water delivery device; a third attachment position for attaching a water level sensor; and a fourth attachment position for attaching a water overflow sensor.Optionally, the subframe component comprises the first attachment position, and further comprising a water inlet valve, such as a solenoid water inlet valve, removably attachable to the first attachment position, wherein the water inlet valve comprises a water inlet, the water inlet comprising a support bracket removably attachable thereto.Optionally, the subframe component comprises the second attachment position, and further comprising a water delivery device removably attachable to the second attachment position, said water delivery device comprising a water delivery tube arranged for removable connection with a water outlet connector of a water tank to which said subframe component is arranged to be fitted.Optionally, the subframe component comprises a bayonet-type fitting at the second attachment position for securing the water delivery device by virtue of a corresponding portion on the water delivery device.Optionally, the water delivery device comprises a pump and a siphon.Optionally, the water delivery device has a body, with an inlet at a lower part of the body, wherein the second attachment position is located relative to the engagement portion such that when the subframe component is mounted in said water tank and the water delivery device is mounted to the subframe component, the inlet of the water delivery device is positioned adjacent to the bottom of the tank while allowing water ingress from the tank into the inlet of the water delivery device.Optionally, the water delivery device comprises a number of side openings at least partly around a perimeter of the lower part of the body, and optionally wherein the side openings are in the form of castellations.Optionally, the subframe component comprises the third attachment position, and further comprising a water level sensor removably attachable to the third attachment position, the water level sensor arranged for sensing, by virtue of a relative position of the water level sensor versus the engagement portion, when a water level inside a water tank to which said subframe component is arranged to be removable mountable has reached a first predetermined level.Optionally, the subframe component comprises the fourth attachment position, and further comprising a water overflow sensor removably attachable to the fourth attachment position, the water overflow sensor arranged for sensing, by virtue of a relative position of the water overflow sensor versus the engagement portion, when a water level inside a water tank to which said subframe component is arranged to be fitted has exceeded a second predetermined level. According to a fourth aspect of the present disclosure there is provided a water tank assembly of an air-assisted water closet, the water tank assembly comprising: a water tank; and the subframe component of the third aspect.Optionally, the water tank assembly comprises a primary water containment volume, and has a water outlet connector through a wall of a lower portion of the primary water containment volume, said water outlet connector arranged for removable connection inside the water tank with a water delivery tube of a water delivery device.Optionally, the water outlet connector comprises a first one-way valve allowing egress of water from the water delivery tube to a first external pipe connection of the water outlet connector, and preventing ingress of fluid from the first external pipe connection.Optionally, the water tank assembly further comprises a float indicator mounted through the water tank and arranged to indicate an under-filled condition of the water tank by virtue of buoyancy.Optionally, the water tank assembly further comprises an overflow weir separating an overflow volume of the water tank from a primary water containment volume of the water tank, and further comprising an overflow outlet through a wall of a lower portion of the overflow volume.Optionally, the overflow outlet comprises a second one-way valve allowing egress of water from the overflow volume to a second external pipe connection of the overflow outlet, and preventing ingress of fluid from the second external pipe connection.Optionally, the water tank assembly further comprises an auxiliary overflow opening through a wall of the water tank, wherein a lower edge of the auxiliary overflow opening is arranged such that in use it is positioned higher than a top edge of the overflow weir and is positioned lower than an opening of a water inlet spout of the water tank assembly.Optionally, the water tank assembly further comprises one or more mounting features, wherein optionally said mounting features comprise at least one recess arranged for engagement with a corresponding protrusion of a corresponding mount, and / or at least one protrusion arranged for engagement with a corresponding recess of a corresponding mount.Optionally, the water tank comprises an attachment position for a removably mountable support bracket for supporting a water inlet pipe connection.Optionally, the water tank assembly further comprises a cable tray at an upper portion of the water tank, for managing cables of electrical components that in use are mounted inside the water tank assembly.Optionally, the water tank assembly is additionally provided with a 2-to-1 connector pipe arranged for joining the first external pipe connection and the second external pipe connection to provide a combined water outlet.Optionally, the pipe connections of the 2-to-1 connector pipe are quick-release connections each comprising an O-ring seal and securing means, and optionally wherein the securing means is a retaining clip that is selectably engageable with both said connector pipe and said external pipe connections. According to a fifth aspect of the present disclosure there is provided a waste valve assembly for an air-assisted water closet, the waste valve assembly comprising:a valve body having a selectively closable opening therethrough;a valve shutter located in the valve body and movable between at least two positions, wherein in a first position the opening is at least partially open, and in a second position the opening is closed;an actuator connectable to the valve shutter for moving the valve shutter between the first position and the second position; anda chassis,wherein the chassis comprises mounting positions for the valve body and the actuator, and wherein a guard hoop extends from the chassis and at least partially surrounds the actuator mounting position to define an area inboard of the guard hoop within which a whole range of movement of the actuator is accommodated. Optionally, the waste valve assembly further comprises an electric motor arranged for driving the actuator and thereby moving the shutter between the first and second positions, and optionally, the actuator is a linear actuator and the valve body and valve shutter are arranged as a gate valve configuration.Optionally, the waste valve assembly further comprises a lubrication fitting for a maintenance operator to add lubricant to the waste valve assembly when the waste valve assembly is in-situ.Optionally, the valve body comprises a pipe fitting on at least one of an inlet and an outlet side of the waste valve assembly, and optionally wherein the pipe fitting comprises at least one of a collar and a flange. According to a fifth aspect of the present disclosure there is provided a method executed by a controller of an air-assisted water closet, the method comprising the following steps:conditional upon a lid of a waste pan of the air-assisted water closet being closed, causing the opening of a waste valve that controls flow between the waste pan and a drainage system into which the waste pan is intended to drain;commencing a combined air and water flushing cycle; andupon completion of the combined air and water flushing cycle, causing the closing of said waste valve. Optionally, the method further comprises: responsive to detecting the opening of the waste pan lid while the waste valve is open, terminating any flushing cycle that is in progress, and causing the closing of the waste valve.Optionally, the method further comprises: upon commencing the combined air and water flushing cycle, causing an optical indicator on a part of the air-assisted water closet to indicate that a flushing cycle is in progress; and upon completion of the combined air and water flushing cycle, causing said optical indicator to cease indicating that a flushing cycle is in progress.Optionally, the method further comprises: upon at least one of commencing the combined air and water flushing cycle and completing the combined air and water flushing cycle, such as after the completing of one or more combined air and water flushing cycle, causing the sending of a message to a computer server, said message containing data relating to said flushing cycle (or, more generally, relating to one or more combined air and water flushing cycles).Optionally, the combined air and water flushing cycle further comprises the following steps: upon commencement of a combined air and water flushing cycle, causing a water pump of a water delivery device to run for a first predetermined time period, such that said water pump urges water through a siphon arrangement of the water delivery device, to the waste pan from a water tank pre-filled with a predetermined volume of water; after the first predetermined time period, causing the water pump to stop, whereupon water flow into the waste pan continues by virtue of action of said siphon; causing an air pump to run for a second predetermined time period, such that said air pump provides air to the waste pan, and such that water flow through said siphon is stalled by resulting back-pressure from the waste pan to the water tank; after the second predetermined time period, ceasing causing the air pump to run; and waiting for a third predetermined time period to allow the air pump to stop and to allow action of the siphon to resume and complete, constituting completion of the combined air and water flushing cycle.Optionally, the method further comprises triggering a maintenance condition wherein the waste valve is caused to open and to remain open until an reset operation is performed by a user, said maintenance condition being triggered by detecting a specific sequence of user-operations of a sensor, and optionally the maintenance condition further comprises activating the air pump for a predetermined time period when the lid of the waste pan is closed.Optionally, the method further comprises: upon causing the opening of said waste valve, monitoring an electrical current drawn by an electric motor driving an actuator of said waste valve, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a predetermined threshold, then detecting an error and aborting the combined air and water flushing cycle.Optionally, the method further comprises: prior to commencing the combined air and water flushing cycle, sensing a water level in a water tank of said air-assisted water closet, and if too low or too high then detecting an error and optionally deferring any combined air and water flushing cycle.Optionally, the method further comprises: upon activating an air pump for providing to the waste pan the air of said combined air and water flushing cycle, measuring an electrical current drawn by a motor of said air pump, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a predetermined threshold then detecting an error and optionally aborting the combined air and water flushing cycle.Optionally, the method further comprises: upon activating a water pump for providing to the waste pan the water of said combined air and water flushing cycle, measuring an electrical current drawn by a motor of said water pump, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a threshold then detecting an error and optionally aborting the combined air and water flushing cycle.Optionally, the method further comprises: upon activating a water inlet valve, such as a solenoid water inlet valve, for admitting water into a water tank of said air-assisted water closet, measuring an electrical current drawn by said water inlet valve, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a threshold then detecting an error and optionally deferring any combined air and water flushing cycle.Optionally, the method further comprises: signalling any detected errors to a remote server over a network, and / or indicating any such error on an optical indicator on a part of the air-assisted water closet.Optionally, the method further comprises: recording data related to the flush cycles that are performed, and periodically sending said data to a server over a network.Optionally, the method further comprises: determining from said data that maintenance is required when a number of flush cycles exceeds a predetermined threshold, and indicating that determination by sending a message to said server and / or by activating an optical indicator on a part of the air-assisted water closet. According to a sixth aspect of the present disclosure there is provided a controller unit arranged to carry out the method steps of the fifth aspect.Optionally, the controller unit further comprises an optical indicator that is arranged to indicate at least one of (i) when a flush operation is in progress, and (ii) when a state requiring attention exists such as a detected error or a determined maintenance requirement.Optionally, the controller unit further comprises a housing for mounting a circuit assembly, wherein the circuit assembly comprises at least one processor arranged for carrying out the method steps, and the housing is arranged to fit directly on top of the water tank assembly of the fourth aspect, thereby forming a lid of said water tank assembly.Optionally, the controller unit further comprises a network interface configured for communicating status of the controller unit to a data server across a network, and optionally the network interface is a wireless network interface. According to a seventh aspect of the present disclosure there is provided a computer-implemented method comprising the following steps:receiving, over a network, data indicative of a number of flush operations performed by an air-assisted water closet;based on said data, determining whether or not a maintenance operation is due;andif a maintenance operation is due, signalling via a network, an electronic messageaddressed to a maintenance operator, said electronic message containing data instructing the performance of said maintenance operation on a particular air-assisted water closet associated with the data. According to an eighth aspect of the present disclosure there is provided a computer-implemented method comprising the following steps:receiving, over a network, data indicative of an error state associated with an air- assisted water closet;based on said data, determining that a maintenance operation is required; and signalling via a network, an electronic message addressed to a maintenanceoperator, said electronic message containing data instructing the performance of said maintenance operation on a particular air-assisted water closet associated with the data. Optionally, in the method of the seventh or eighth aspects, each one of a plurality of air-assisted water closets is associated with a respective unique node address, and each node address is associated with a respective physical location.Optionally, each node address or physical location is associated with addressing information by which an electronic message can be sent to a particular maintenance operator, and wherein said addressing information is used to send, to said particular maintenance operator, the electronic message containing data instructing the performance of said maintenance operation. According to a ninth aspect of the present disclosure there is provided a computer program product comprising machine-readable instructions that when executed by one or more processors causes the one or more processors to carry out the method of any of the fifth, seventh and / or eighth aspects.According to a tenth aspect of the present disclosure there is provided a computer- readable medium storing machine-readable instructions that when executed by one or more processors causes the one or more processors to carry out the method of any of the fifth, seventh and / or eighth aspects. According to an eleventh aspect of the present disclosure there is provided an air- assisted water closet including a mount as defined in the first aspect, a cistern assembly as defined in the second aspect, a subframe component as defined in the third aspect, a water tank assembly as defined in the fourth aspect, a waste valve assembly as defined in the fifth aspect, and / or a controller unit as defined in the sixth aspect, a computer program product as defined in the ninth aspect and / or a computer-readable medium as defined in the tenth aspect. It will be appreciated in the light of the present disclosure that certain features of certain aspects and / or embodiments described herein can be advantageously combined with those of other aspects and / or embodiments. The following description of specific embodiments should not therefore be interpreted as indicating that all of the described steps and / or features are essential. Instead, it will be understood that certain steps and / or features are optional by virtue of their function or purpose, even where those steps or features are not explicitly described as being optional. The above aspects are thus not intended to limit the scope of the present invention which is instead defined by the appended claims. Description of FiguresAspects of the disclosure may be carried out in various ways and some preferred embodiments will now be described by way of example only and in a non-limiting way with reference to the accompanying drawings, in which:Figure 1 is a 2-dimensional front view of a cistern assembly according to an embodiment of the disclosure.Figure 2 is a perspective view of said cistern assembly.Figure 3 is a perspective exploded view showing various constituent components of said cistern assembly.Figure 4 is a 2-dimensional left side view of said cistern assembly. Figure 5 is a 2-dimensional underside view of said cistern assembly.Figure 6 is a perspective exploded view of an air pump component of said cistern assembly.Figure 7 is a perspective view of a water tank assembly comprised in said cistern assembly.Figure 8 is a perspective view of a subframe assembly comprised in said water tank assembly.Figure 9 is a first perspective view of a waste valve assembly for use with said cistern assembly.Figure 10 is a second perspective view of a waste valve assembly for use with said cistern assembly.Figure 11 is a perspective exploded view of said waste valve assembly.Figure 12 is a perspective view of a waste pan assembly for use with said cistern assembly and / or said waste valve assembly.Figure 13 is a schematic view of a computer network system comprising network nodes which each correspond to a controller of said cistern assembly.Figure 14 is a representation of a network node hierarchy into which network nodes can advantageously be grouped.Figure 15 is a flow diagram depicting method steps performed by a controller of an embodiment.Figure 16 is a flow diagram depicting further method steps performed by a controller of an embodiment.Figure 17 is a flow diagram depicting method steps performed by a network server. Figure 18 is a flow diagram depicting method steps performed by a network server.Figure 19 is a representation of an example web-based application, which can be executed on the network (cloud) server, specifically a login screen of said application.Figure 20 is a representation of an administrator-level display generated by said application.Figure 21 is a representation of a partner-level display generated by said application.Figure 22 is a representation of a customer-level display generated by said application.Figure 23 is a representation of a building-level display generated by said application.Figure 24 is a representation of a washroom-level display generated by said application. Detailed DescriptionExisting designs of air-assisted water closets, and associated operating methods, have proved successful but not entirely optimal. The presently disclosed cistern assembly, waste valve assembly, and methods of operating said assemblies, overcome, at least to an extent, drawbacks in said existing designs, as will be described below. By way of introduction, certain problems addressed by the solutions provided in the present disclosure will now be briefly discussed.Some existing air displacement toilets (otherwise termed “air-assisted water closets”) have been found to be noisy, with undesirably high sound levels negatively affecting acceptance levels and thereby reducing the widespread employment of such toilets, negating somewhat the potential water efficiency advantages provided by such devices. The disclosed apparatus and method herein improve on existing designs, in part by the use of a tangential centrifugal air pump, combined with a vibrationally-insulated mounting arrangement, a cover, a sound damper (e.g. foam strip) between motor and cover, and a downward and / or rearward-facing inlet orifice. These features combine to effectively reduce sound pressure levels and vibration transmission.Furthermore, some existing air-assisted toilets are at risk of backflow into the waste pan in situations when a building’s drains have become blocked. The present disclosure solves such problems by the addition of an electromechanical waste valve, appropriately controlled, which prevents reverse flow of water and / or solids when the waste pan’s lid is open and / or a flushing operation is not in progress.A further problem with some existing toilets is that they use float operated inlet valves to allow water into the cistern, and the pressure which float-operated inlet valves require to close is affected by the inlet water pressure, which means that the water level in the cistern can fluctuate. Such fluctuation is undesirable, since air-assisted toilets are required to flush using an exact amount of water, to meet regulatory standards relating to flush performance. In addition, float-operated inlet valves are subject to frequent failure which allows water to leak by, such failures often being unreported and thus unremedied for long periods of time, potentially wasting 1,000’s of litres of water per year. The present disclosure solves these problems by the use of an electrically-operated solenoid valve, combined with a water level sensor switch used to control the solenoid. Additionally, the use of a secondary water level sensor to detect and report overflow due to valve failure to maintenance personnel reduces water wastage in such an event.Additionally, existing toilets house all components inside the cistern. It is conventional for those components to be supplied separately and require assembly onsite. That makes installation and maintenance difficult and time consuming, and allows for installer error, especially so in the case of existing air-assisted toilets which comprise more parts than traditional water-flush toilets. The present disclosure solves this problem by the use of a back plate (or “mount”) that is arranged for mounting of key sub-assemblies (e.g. cistern assembly, control unit, motor sub assembly), and by the use of a subframe component which fits inside the water tank of the cistern assembly and has provision for mounting sub-components of the water tank assembly (e.g. solenoid valve, water delivery pump / siphon, level sensor and overflow sensor). For example, the sub-assemblies can be press-assembled during installation, and are easy to access in subsequent servicing and maintenance operations. Installation can be further eased by the optional use of a 2-to-1 manifold, including 2x non return valves, which allow the water tank’s overflow outlet to drain into the waste pan and thereby remove the need for a separate overflow pipe.Furthermore, existing toilets are prone to failure modes due to wear and tear, and frequent user abuse. For example, it is often the case with existing toilets that the first time that a failure is known about is when someone wants to use the toilet but finds it broken, potentially leading to a poor user experience. In the case of air-assisted toilets, this can lead to reduced acceptance of such water-saving devices, and resultingly limited deployment and enjoyment of the water-saving benefits thereof. To address this it has been traditional to employ preventative maintenance programmes with regular cleaning and component replacement cycles to ensure that toilets are working, however in a building with multiple toilets this can still result in periods of time between maintenance visits where toilets have failed, and can also mean that components are unnecessarily changed (on a preventative basis) on toilets that have only seen relatively low use (observation shows that a bank of toilets will not see equal use). The present disclosure solves this by the addition of a controller unit incorporating a network node (e.g. an “Internet-of-Things” or “IoT” node), thereby allowing flush count and fault data to be captured in real time, logged by a server, and shared with an operator and / or with users (e.g. maintenance staff) to alert them to faults in good time, and to advise users of maintenance needs on a toilet by toilet basis. Failure patterns can also be rapidly identified, such that common faults can be investigated and addressed by revision to component designs.Referring to Figures 1 to 5, particularly Figure 3, a mount (or “backplate”) 110 for a cistern assembly 100 of an air-assisted water closet is provided. The mount 110 is preferably made from steel, zinc coated for corrosion resistance. In an embodiment, the mount 110 comprises a first portion 118 which is generally planar and arranged in a first plane. The first portion 118 has a first side and a second side opposite the first side, the first side being a front side when in use and the second side being a rear side when in use (e.g. when installed in a washroom), said rear side being fixable to an object such as a wall of a building. The mount 110, particularly the first portion 118, comprises one or more first mounting features (e.g. holes) 111 for fixing the mount 110 to such a wall. The mounting features 111 at a lower edge of the mount may comprise slots for sliding over screws that are previously screwed into the wall for ease of mounting by taking the weight of the mount while further mounting features 111 receive further screws. Optionally, the mount 110 can comprise further holes for economy of material and / or to reduce weight. The mount 110 further comprises one or more second mounting features 115, 116, e.g. mounting studs 115 and / or tabs 116 and / or holes, for mounting a water tank assembly 120 to the mount 110, optionally using fixings such as threaded fasteners. In the present example, at least one or more (such as two) of the second mounting features 116 are mounted at the transition 113 between the second portion 119 (which lies in the second plane) forward from the first portion 118 to support the weight of the water tank while being further secured by the second mounting features 115. The mount 110 further comprises one or more third mounting features 114 for mounting an air pump assembly 140 to the mount 110.Optionally, the mount 110 further comprises a second portion 119, the second portion 119 being generally planar and arranged in a second plane, the second plane being parallel to and spaced apart from the first plane in a direction away from the second (rear, when installed / in use) side of the first portion 118 and towards the first (front when installed / in use) side of the first portion 118. Preferably, the second portion 119 comprises an opening 112 through the second portion 119, for air to pass through, and the second portion 119 comprises the third mounting features 114. Thus, the second portion 119 constitutes a section of the mount 110 which is “raised” away from a wall upon which the mount 110 is attached, thereby allowing air to pass through the opening 112 even when the mount 110 is attached to a wall. The opening 112 and the third mounting features 114 are positioned relative to each other such that when an air pump 140 is mounted to the mount 110 using the third mounting features 114, a cooling air inlet 147 (referring to Figure 6) of the air pump 140 aligns with the opening 112 so as to admit air into the cooling air inlet 147 for cooling a motor 143 of the air pump 140. The displacement of the second portion 119 (which lies in the second plane) forward from the first plane in which the first portion 118 lies (said first portion 118 when in use being mounted to an object e.g. a wall) provides that the cooling air inlet 147 of the air pump 140 faces the wall, but cooling air can still be admitted into the air pump 140 for circulating around the motor 143 by virtue of the resulting gap between the second portion 119 and the wall. Such placement of the cooling air inlet 147 results in quieter operation because the opening 112 and cooling air inlet 147 are directed towards the wall and away from a user of the water closet.Optionally, the second portion 119 comprises one or more alignment features 117, such as slots extending at least partially around a circumference of a circle outward of and concentric with the opening 112, with which a cover 141 of the air pump 140 can engage when the air pump 140 is mounted to the front side of the second portion 119, thereby aligning the air pump 140 and its cover 141 with the mount 110.Optionally, the one or more second mounting features 115, 116 for mounting a water tank assembly 120 to the mount 110 comprise at least one protrusion (such as mounting studs 115 and / or tabs 116) arranged for engagement with a corresponding recess (such as mounting holes 1212) of a corresponding water tank component of a water tank assembly 120, and / or the one or more second mounting features comprise at least one recess arranged for engagement with a corresponding protrusion of the corresponding water tank 1215 component. By way of example, these features provide easier mounting and alignment than conventional use of threaded fasteners. Correspondingly, the water tank 1215 comprises one or more mounting features 1212 for mounting said water tank 1215 to the mount 110. Said mounting features 1212 optionally comprise at least one recess or opening arranged for engagement with a corresponding protrusion (e.g. mounting features 115 of the mount 110) of said mount 110, and / or the mounting features 1212 of the water tank 1215 can optionally comprise at least one protrusion arranged for engagement with a corresponding recess of said mount 110, and / or said mounting features can optionally comprise a feature suitable for engagement with a fastener. Thus, simpler and more effective attachment of the water tank assembly 120 to the mount 110 is provided for, which eases installation and reduces assembly errors, thereby improving reliability.As illustrated in Figures 1 to 5, a cistern assembly 100 can be provided, comprising, in an embodiment: the mount 110 and at least one of a water tank assembly 120 and an air pump assembly 140, the sub-components of which will be described further below. The components of the cistern assembly 100 can be pre-assembled to the mount 110, thereby reducing installation effort and errors, and so increasing reliability. Alternatively, the water tank assembly 120 and / or the air pump assembly 140 can be supplied detached from the mount 110, but nevertheless the provision of the mount 110 permits easier assembly and disassembly / repair / replacement of components, compared with existing air-assisted water closets in which all cistern assembly components are typically contained within the cistern assembly which hinders maintenance.Referring to Figure 6, in embodiments, the air pump assembly 140 comprises a pump body (or “rear housing”) 144, a pump motor 143 coupled to an impellor inside an impellor housing 149, said impellor housing 149 having an impellor air inlet 142, e.g. in its end face as illustrated. An assembly comprising the pump motor 143 and impellor housing 149, is mounted to the pump body 144 by a number of (e.g. 3) vibrational insulators (or anti- vibration mounts, e.g. rubber bobbins) 145. This reduces noise transmission from the rotational mass of the motor 143 and impellor to the mount 110, and thus reduces noise transmitted to the building environment when the pump body 144 is mounted to the mount110. The air pump 140 further comprises an air pump cover 141 which covers the motor 143 and impellor housing 149, and comprises at least one cover air inlet 148 (for example one or more openings at an underside of the cover 141, such as one or more slots as shown in Figure 5) for admitting air into the air pump cover 141 from where it can enter the impellor air inlet 142. In some other examples, the impellor air inlet 142 is configured to draw air through the opening 112, such as by being positioned adjacent thereto or by being connected to the opening 112 via a conduit (not shown). More generally, the impellor air inlet 142 and / or the cooling air inlet 147 is positioned adjacent to or fluidly connected to the opening 112 via a conduit (not shown). The downward facing orientation of the cover air inlet 148 assists with reduction of noise experienced by a user when the pump motor 143 is in operation, because there is no direct path from the opening of the cover air inlet 148 to a user’s ear, and because of a filtering effect resulting from the enclosed volume inside the cover 141. The air pump cover 141 also assists with the direction of airflow from the cooling air inlet 147 to around the pump motor 143 for cooling said pump motor 143, improving cooling and reducing noise experienced by a user. Optionally, a noise reducing material such as sound-insulating foam damper 1410 can be interposed between the air pump cover 141 and the pump motor 143 and / or impellor housing 149 so as to further reduce noise levels that are transmitted from the motor 143 and / or impellor housing 149 to the building environment.The air pump 140 is preferably of a centrifugal type, since that type of pump is relatively easy to balance and inherently has lower noise characteristics than rotary vane pumps used in some existing air-assisted water closets. A further advantage of the centrifugal type of air pump 140 described in the present application is that it tends to produce a smoothly-ramped increase / decrease in air pressure, building pressure and dissipating pressure gradually as it is operated, rather than a relatively instant transition in air pressure which rotary vane pumps can produce, and this smoothly-ramped transition in air pressure is less likely to cause pressure shocks which could cause the waste pan lid (e.g. as shown in Figure 19) to rattle and degrade user-experience. As shown in Figures 4 and 5, the air outlet 146 of the air pump 140 is tangential to the rotation of the impellor inside the impellor housing 149, and preferably when the air pump 140 is mounted to the mount 110 the air outlet 146 exits the impellor housing 149 in a downward direction for easy connection (e.g. via a flexible hose, attached using pipe clips) to the waste pan 171 at the waste pan’s air inlet connection 173 (see Figure 12).Referring to Figure 7, the water tank assembly 120, as previously shown in Figures 1 to 5, comprises a water tank 1215, and embodiments further comprises components as detailed below. The water tank 1215 has an attachment position 1213 for attaching a removable subframe component 131 of a subframe assembly 130. The subframe component 131 in turn has provision for mounting further components on it, as described below, and in embodiments comprises said further components. It will be appreciated that said water tank 1215 and / or subframe component 131 can be supplied with said further components assembled to them, or supplied with said further components unassembled.Referring to Figures 7 and 8, the subframe component 131 of the subframe assembly 130 is arranged to be removably mountable in the water tank 1215 of the water tank assembly 120, by virtue of the subframe component 131 comprising an engagement portion 1311 which is arranged to engage with a corresponding portion of the water tank 1215. For example, the subframe component 131 comprises an inverted “U” shaped portion which is arranged to engage with a top edge of a horizontal wall of the water tank 1215. Optionally, further securing means such as a screw or other fastener can be included to enhance security of engagement between the subframe component 131 and the water tank 1215. The subframe component 131 can be formed, for example, by injection moulding of plastics material, or by forming sheet metal, or by casting of a metal, or by any other appropriate construction technique including additive manufacturing.The subframe component 131 is provided with respective attachment positions for a plurality of further components of the subframe assembly 130 (which in turn are thus further components of the water tank assembly 120). Such further components of the subframe assembly 130 include at least two of: an electrical solenoid water inlet valve 132 (which in turn comprises a water inlet 133 and a water spout 134); a water delivery device 135 (which in embodiments comprises a water pump, a siphon, and a water delivery tube 127); a water level sensor 136 (e.g. a float switch); and a water overflow sensor 137 (e.g. a second float switch) mounted higher in use than the water level sensor. By providing a subframe component 131 on which at least two components can be mounted, it is provided that at least some components of the water tank assembly 120 can be pre-assembled off- site, prior to installation of the water tank assembly at an installation site, thereby reducing installation effort and errors, and so increasing reliability. It will be appreciated that the water inlet valve 132 may be mechanically, pneumatically or otherwise operated in other examples.Preferably, but optionally, the subframe component 131 comprises a first attachment position for attaching the solenoid water inlet valve 132, to which attachment position the solenoid water inlet valve 132 is attached when installed. The solenoid water inlet valve has a water inlet 133, and a water spout 134 for delivering water into the water tank 1215. Optionally the water inlet 133 incorporates a 90-degree elbow to aid component packaging within the limited space available, and preferably the water inlet 133 incorporates a push fitting for ease of installation. In advantageous embodiments, the first attachment position is located relative to the engagement portion 1311 (and considering the relative location of the corresponding attachment position 1213 of the water tank 1215) such that when the subframe component 131 and water tank 1215 are assembled together, then even when the water tank 1215 is full and overflowing, the water spout 134 is mounted sufficiently above (e.g. 2cm above) the level of the water in the water tank 1215 so as to prevent reverse siphoning of water from the tank back into the water supply, thereby meeting regulatory requirements. Optionally, the water inlet 133 of the solenoid water inlet valve 132 comprises a support bracket 1310 for supporting the water inlet 133 pipe connection, in which cases the water tank 1215 comprises a corresponding second attachment position 1216 for attachment of said support bracket 1310. The provision of the support bracket 1310 and second attachment position 1216 facilitates simple and convenient removal / replacement of the subframe assembly 130 in the water tank 1215 (e.g. without a need to thread an inlet pipe through a hole in the water tank 1215 and secure it with a nut fitting as is conventional). Preferably, but optionally, the subframe component 131 comprises a second attachment position for attaching the water delivery device 135. The second attachment position is positioned relative to the engagement portion 1311 (and considering the location of the corresponding attachment position 1213 of the water tank 1215) such that when the subframe component 131 and water tank 1215 are assembled together, the water delivery tube 127 of the water delivery device 135 is located in a position suitable for engagement with a water outlet connector 121 of the water tank 1215, for delivering water to an external pipe connection. A push-fit (e.g. using an o-ring 1219) can be provided for the connection between the water delivery tube 127 and the water outlet connector 121, such that the subframe component 131 can more easily be inserted or removed from the water tank 1215, while avoiding leakage. Optionally, the subframe component 131 comprises a bayonet fitting at the second attachment position for removably securing the water delivery device 135 to the subframe component 131, the water delivery device 135 having a corresponding portion for cooperating with the bayonet fitting.In a preferred embodiment, the water delivery device 135 comprises a water pump and a siphon, as well as a water inlet 138 for the combined water pump and siphon. The water inlet 138 preferably comprises a skirt portion extending downwards from a body of the water delivery device 135, towards the base of the water tank 1215 when the water delivery device 135 is mounted in the water tank 1215. The water inlet 138 comprises at least one side opening in the skirt portion, preferably a number of side openings in the form of castellations, such that when the water delivery device 135 is mounted in the water tank 1215 by virtue of the arrangement of the subframe component 131 and the engagement portion 1311 engaged with the attachment position 1213 of the water tank 1215, the skirt portion of the water delivery device 135 is positioned at the bottom of the water tank 1215. Optionally, the skirt portion is removably mountable to a lower portion of the water delivery device 135 using a push-fit employing an o-ring seal.Thus, in use, the water inlet 138 admits water into the water delivery device 135 (e.g. combined water pump / siphon), more specifically into the water pump. The water pump, when operated, draws water from the water inlet 138 of the water delivery device 135, and pumps said water into said siphon, from which the water exits to the water delivery tube 127 and then out into the water outlet connector 121. When the water pump ceases operation, the action of the siphon causes water flow to continue until the water level in the water tank 1215 drops to the level of the water inlet 138 (preferably in the form of at least one side opening in the skirt), whereupon air is able to be drawn into the siphon which then breaks the siphonic action. The water tank 1215 can then be refilled without flow recommencing. A further function of the at least one side opening is that a sufficient water inlet opening is ensured, regardless of the accuracy (subject to design and manufacturing tolerances) with which the lower skirt of the water delivery device 135 is located near the bottom of the water tank 1215.Preferably, but optionally, the subframe component 131 comprises a third attachment position for attaching the water level sensor 136. The third attachment position is positioned relative to the engagement portion 1311 (and considering the location of the corresponding attachment position 1213 of the water tank 1215) such that when the subframe component 131 and water tank 1215 are assembled together and installed, the water level sensor 136 is located at a height relative to the bottom of the water tank 1215 which corresponds to the water tank 1215 having been pre-filled (before a flushing operation) with a predetermined volume of water (e.g. 1.5L) for delivery to a waste pan 171. The water level sensor 136 can be any known type of water level sensor, such as a float switch, and can be attached to the subframe component 131 by any suitable means such as by a threaded fastener. Said water level sensor 136 is used by a controller 160 (e.g. an electronic controller comprising a processor) to determine when a water level in the water tank 1215 has reached a predetermined level corresponding to the predetermined water volume, and for example to open the solenoid water inlet valve to admit water into the water tank 1215 if the predetermined level has not been reached, or to close the solenoid water inlet valve if the predetermined level has been reached.An advantage of using a water level sensor 136 and controller 160 to control water level by operating said solenoid water inlet valve, is that the water level can be more accurately controlled compared with existing devices which use a ball float valve. That is because ball float valves are subject to the inlet water pressure, since a ball float must apply a corresponding pressure to its inlet valve in order to cancel inlet water pressure and thereby stop water flow, and since the pressure that the ball float must apply (equal to the inlet pressure) can vary then it follows that the level of the water versus the ball float at its stop position must vary, and thus water level varies if it is controlled by a legacy ball float valve. In embodiments of the present disclosure, the water level is independent of inlet water pressure, because as soon as the water level reaches a height sufficient to trigger the water level sensor 136, the controller 160 closes the solenoid water inlet valve, accurately setting the water level. Having the ability to accurately set the water level in the water tank 1215 is advantageous in an air-assisted water closet arrangement for the following reasons. Firstly, it saves water, because in a legacy ball float valve system it can be necessary to set the water level slightly higher than desirable, so as to guard against cases when low water pressure would cause the water level to be too low for adequate flushing, whereas in the presently disclosed embodiments there is no such need to set the water level higher than is desirable. Secondly, it is necessary to ensure that after a flushing operation has been completed, an appropriate level of water is left in the waste pan trap 171, so as to prevent odours entering a toilet cubicle from the drainage system. In a legacy water closet, this is simple to do by merely ensuring that a volume of water that is greater than the volume of the waste trap is flowed into the waste pan (since excess water will simply flow away, leaving the trap full). However, for an air-assisted water closet of the type described herein, which is designed to save water, such crude delivery of water is undesirable, and it is necessary to ensure that an accurately measured volume of water is delivered to the waste pan 171 to refill the trap after a flushing cycle has completed. The aforementioned arrangement employing a water level sensor 136, solenoid water inlet valve 132 and controller 160 permits such an accurately measured volume of water to be delivered to the waste pan 171. This is especially important when a waste valve assembly 150 is employed with the waste pan assembly 170, since when the waste valve 1510 is in the closed state it is not possible for excess water to exit the waste pan 171 into the drainage system, and therefore it is especially important, for a consistent waste pan water level to be achieved, that the amount of water dispensed into the waste pan 171 is accurately measured. Furthermore, the described arrangement is more compact than a legacy ball float valve arrangement, giving benefits in terms of flexibility of packaging the components of the water tank assembly 120.Preferably, but optionally, the subframe component 131 comprises a fourth attachment position for attaching the water overflow sensor 137. The fourth attachment position is positioned relative to the engagement portion 1311 (and considering the location of the corresponding attachment position 1213 of the water tank 1215) such that when the subframe component 131 and water tank 1215 are assembled together and installed, then the water overflow sensor 137 is located at a height relative to the bottom of the water tank 1215 which is higher than that of the water level sensor 136 by a margin that is sufficient to ensure that the water overflow sensor 137 will not be triggered unless the solenoid water inlet valve fails to shut off water ingress to the water tank 1215 when commanded to in response to a controller 160 sensing that the water level sensor 136 has triggered. The overflow sensor 137 is preferably mounted at a level that is slightly lower than the overflow weir 125 so that a leaking solenoid water inlet valve 132 is noticed before actual water loss occurs. The water overflow sensor 137 can be any known type of water level sensor, such as a float switch, and can be attached to the subframe component 131 by any suitable means such as by a threaded fastener. This arrangement saves water compared to existing devices such as those including legacy ball float valves, (i) because ball float valves are subject to multiple failure modes which require manual inspection and therefore typically go unreported and so persist for long periods of time, and (ii) because in the presently disclosed embodiment, any overflow condition resulting from failure of the solenoid water inlet valve is detected by the controller 160 and flagged to an operator, and can be automatically notified to a maintenance person for remedying.Referring to Figure 7, in embodiments of the present disclosure, a water tank assembly 120 can be provided, comprising the aforementioned water tank 1215 and the aforementioned subframe component 131 (or optionally the subframe assembly 130 complete with its further components assembled to it).The water tank 1215 can be constructed from a plastics material, e.g. by using injection moulding or vacuum forming, or can be constructed from metal, e.g. folded sheet metal or cast metal, or constructed by any other appropriate construction technique including additive manufacturing. In a preferred embodiment plastic injection moulding is used. At an upper portion of the water tank 1215 there is provided a cable tray 1217 for managing cables of electrical components that when installed are mounted inside the water tank assembly 120, thereby improving reliability by preventing such cables from being submerged. Thus, in particular, the cable tray 1217 may be provided at the upper portion of the water tank 1215 above an overflow level (defined by overflow weir 125) of the water tank. Optionally, as shown in Figure 7, one or more maintenance attachment points 1218 can be provided on the water tank 1215 for attaching the controller 160 (via corresponding features on the controller enclosure base 161) to the water tank when the controller 160 has been removed from the top of the water tank 1215 for access to the internal components of the water tank 1215 during maintenance.The water tank 1215 further comprises a primary water containment volume 123 into which the subframe component 131 is receivable, the subframe component 131 being securable to a first attachment position 1213 of the water tank 1215. The water tank 1215 optionally also comprises a second attachment position 1216 for attaching a support bracket 1310 for a water inlet 133 of a solenoid water inlet valve 132 that can be mounted to the subframe component 131. The provision of the support bracket 1310 and second attachment position 1216 facilitates simple and convenient removal / replacement of the subframe assembly 130 in the water tank 1215, e.g. without a need to thread an inlet pipe through a hole in the water tank 1215 and secure it with a nut fitting as is conventional, and thus assembly / maintenance effort and resultant errors are reduced.At a lower portion of the primary water containment volume 123 there is provided a water outlet connector 121, which is arranged inside the water tank 1215 for receiving a water delivery tube 127 of the water delivery device 135, and which water outlet connector 121 is also arranged outside of the water tank 1215 for connecting to an external pipe suitable for connection to a water inlet 174 of the waste pan assembly 170. Preferably the water tank 1215 incorporates a first one-way valve at or in the water outlet connector 121 for preventing backflow (ingress of fluid) into the water tank 1215 from the external pipe.Preferably, but optionally, the water tank 1215 further comprises an overflow volume 124 that is separated from the primary water containment volume 123 by an overflow weir 125 which has a wall height that corresponds to a water level at which any excess water in the primary water containment volume 123 is desired to overflow into the overflow volume 124. At a lower portion of the overflow volume 124 there is provided an overflow outlet 126, which is arranged outside of the water tank 1215 for connecting to an external pipe. That external pipe can be separate from the external pipe that is connected to the water outlet connector 121 and can thus lead to a separate drain, or the overflow outlet 126 can be connected in common with the water outlet connector 121, to the water inlet 174 of the waste pan assembly 170 (for example using a 2-to-1 connector pipe 128). Preferably if the overflow outlet 126 is to drain in common with the water outlet connector 121, or otherwise optionally, the water tank 1215 incorporates a second one-way valve at or in the overflow outlet 126 for preventing backflow (ingress of fluid) into the water tank 1215. In order that an overflow condition can be detected, the water overflow sensor 137 is arranged so as to trigger at a water level that is higher than a normal water level than triggers the water level sensor 136, but lower than the wall height of the overflow weir 125. Thus, if the solenoid water inlet valve 132 fails in the open state, the controller 160 is notified, in which case the controller 160 causes the waste valve 1510 to open so that water overflowing into the waste pan 171 can exit into the drainage system.Optionally, the water tank assembly 120 can be provided with a 2-to-1 connector pipe 128 that is arranged to fit to both the water outlet connector 121 and the overflow outlet 126 external to the water tank 1215, joining them into a combined water outlet 1210 that carries both water from the water delivery device 135 and overflow water, such that both water sources can drain into the waste pan 171 of the pan assembly 170, thereby reducing installation effort by eliminating any need for a separate overflow pipe to be provided and connected. The combining of those two outlets into a combined water outlet 1210 by the use of the 2-to-1 connector pipe 128 is supported by the presence of a one-way valve 129 in each of the water outlet connector 121 and the overflow outlet 126, which one-way valves 129 permit water to exit the water tank 1215 but prevent fluids such as air, water or waste, from entering the water tank 1215. This has the effect that when the waste pan 171 is pressurised by the air pump 140 of the cistern assembly 100, pressure is able to build in the 2-to-1 connector pipe 128 (e.g. instead of leaking through the overflow outlet 126 into the water tank 1215) and thus close the one-way valve 129 of the water outlet connector 121, thereby stalling water flow (that would otherwise continue regardless of water pump operation, due to action of the siphon) from the water delivery device 135.Optionally, said 2-to-1 connector pipe 128 can be arranged to connect to said water outlet connector 121 and / or said overflow outlet 126 using quick-release connectors 139,e.g. comprising push-fit connectors with an o-ring seal. Further optionally, each pipe connection is retained together by a respective pipe retaining clip 1211 that is selectably engageable with both of (i) said 2-to-1 connector pipe and (ii) the respective one of the water outlet connector 121 and said overflow outlet 126, thereby retaining the 2-to-1 connector pipe in engagement with the respective outlets to which it is fitted. The combined water outlet 1210 can be connected by a flexible hose and suitable pipe retaining clips to the water inlet 174 of the pan assembly 170.Optionally, the water tank 1215 further comprises an auxiliary overflow outlet 1214, comprising an opening (e.g. a letterbox shaped opening, optionally including vertical bars to prevent insertion of objects) through a wall of the water tank 1215, with the lower edge of said opening arranged at a height from a base of the water tank 1215 as installed, such that if the overflow outlet 126 proves to be blocked or inadequate for handling a particular rate of water flow into the water tank 1215, then excess water is able to exit the water tank 1215, ensuring that the level of water inside the water tank 1215 never exceeds a maximum safe level below the water inlet spout 134, thereby protecting the water supply against back- siphoning in the event of transitions from high to low water inlet pressure.Further optionally, the water tank 1215 can comprise a float indicator 122 mounted through a wall of the water tank 1215 and arranged to indicate an under-filled condition by virtue of buoyancy, without relying upon electrical power to the controller 160 being present, and without requiring the lid of the water tank 1215 to be removed for inspection of the water level. Preferably, said float indicator 122 is arranged such that it rises by virtue of buoyancy to a highest position when the level of water in the water tank 1215 is at the correct level for normal operation of the water closet, and said float indicator 122 falls to indicate an under- filled condition if the level of water in the tank is lower than optimal for normal operation. A corresponding scale can be provided on the water tank 1215 exterior so that a pointer of the float indicator 122 can indicate the amount of under-fill.Referring to Figures 1 to 5, a controller unit 160 is provided, having a controller enclosure lid 162 and a controller enclosure base 161, which is preferably but optionally mounted on top of the water tank 1215, thereby enhancing packaging efficiency, and simplifying routing of control wires between the controller unit 160 and the sensors, solenoid valve and pump. Optionally, the cable tray 1217 of the water tank 1215 is included for enhancing cable management (to hold cables away from water inside the water tank 1215). The controller housing can be injection moulded from plastics material, or formed from metal sheet, or cast from metal, or can be constructed using any suitable method including additive manufacturing.In an embodiment, the controller unit 160 comprises a power inlet 163, which can be arranged for accepting mains power such as ~110V or ~230V AC, or can be arranged for accepting a low voltage feed such as 24V DC (optionally, the controller can further include a battery-back up power source). The controller unit 160 further comprises a power outlet 164 for feeding power to the air pump 140 when required, which similarly can output~110V or ~230V AC mains power, or can output a lower voltage such as 24V DC, depending upon the requirements of the air pump 140. Internally to the controller unit 160, there is provided a power converter for converting either mains or battery power into the various voltages required in the controller and required by the other electrical / electronic components comprised in the cistern assembly 100. The controller unit 160 further comprises an auxiliary connector 165 for connection to a network (which can be either a wired network or a wireless network, or both), and optionally the controller unit 160 comprises a wireless modem, constituting a wireless network node 185 as shown in Figure 13, by which status and errors can be reported to a cloud server 183, preferably via a gateway 184.In the controller enclosure lid 162 there is provided a status indicator led 166, which is arranged to indicate status by predetermined encoded flashes and / or colours having predetermined meanings, as can easily be defined in any arbitrary manner. A cable connector 167 exits underneath the controller unit 160, providing electrical connections for connecting to the drive motor 153 of the waste valve assembly 150, and to a lid sensor of the waste pan assembly 170. Inside the controller unit’s enclosure, a circuit board is provided comprising circuitry for executing control of a water closet, for example the circuit board comprising at least one processor with at least random access memory and non- volatile storage storing program instructions, that when executed by the processor, cause the processor to execute a control method as will be described further below with reference to Figures 15 to 16.Referring to Figures 9 to 11, a waste valve assembly 150 for an air-assisted water closet is provided. In an embodiment, said waste valve assembly 150 comprises a waste valve 1510 comprising a valve body 157 which has a selectively closable opening 158 therethrough, and a valve shutter 156 located in the valve body 157. Said valve shutter 156 is movable between at least two positions, e.g. a first position in which the valve opening 158 is at least partially open to permit liquids and / or solids to pass therethrough, and a second position in which the valve opening 158 is closed to prevent liquids and / or solids from passing therethrough. The waste valve assembly 150 further comprises an actuator 154 that is connectable (and when in use is connected) to the valve shutter 156 for moving the valve shutter 156 between the first and second positions. In an embodiment a connecting rod 155 is provided for connecting the actuator 154 to the valve shutter 156. The waste valve assembly 150 optionally further comprises a lubrication fitting such as a grease nipple for providing an operator the ability to inject grease or other persistent lubricant into the assembly 150 when in-situ, for example using a corresponding tool such as a grease gun, for the purpose of maintenance so as to extend the operating lifetime of the waste valve assembly 150.The waste valve assembly 150 further comprises a chassis 151 upon which the valve body 157 and actuator 154 can be mounted, by virtue of the chassis 151 having corresponding mounting positions. The chassis comprises a guard hoop 152, which extends from the chassis and at least partially surrounds the mounting position for the actuator 154, to define an area inboard of the guard hoop 152 within which a whole (e.g. entire) range of movement of the actuator 154 is accommodated. In this way, it is ensured that the actuator 154 (and connecting rod 155 if included) do not extend beyond the guard hoop 152 at any point of their range of movement. Thus, when the waste valve assembly 150 is installed (e.g. at the back of a waste pan 170), provided that an installer installs the waste valve assembly 150 into a space that is able to accommodate the guard hoop 152, it is ensured that the installation space is capable of accommodating the full range of movement of the actuator 154 and connecting rod 155. This ensures that full opening of the valve shutter 156 is possible when installed and in use, thereby reducing installation problems and improving system reliability. In a preferred embodiment, the actuator 154 is a linear actuator, and is driven by a drive motor 153 which is coupled to the actuator 154 and is mounted on the chassis 151. Preferably, the waste valve 1510 is a gate valve with a sliding shutter, since such a valve is less prone to having its operation blocked.In embodiments, the waste valve assembly 150 comprises a pipe fitting (e.g. a collar or flange) on an inlet side and / or an outlet side of the waste valve 1510 (which comprises the valve body 157 and the valve shutter 156), such that a pipe can be conveniently attached to said pipe fitting(s) e.g. by a pipe clip. When installed, one side of the waste valve assembly 150 is coupled to the waste outlet 172 of a waste pan 170, and the other side of the waste valve assembly 150 is coupled to a drainage system (e.g. the drainage system of a building).In use, the waste valve 1510 is opened during a flush cycle and otherwise closed. If the lid of the waste pan 170 is opened then the waste valve 1510 is immediately closed and any flush cycle in progress is aborted. This prevents potential problems with the occurrence of backflow into the waste pan 170 when a number of water closets are connected to a common drain pipe, and when a building’s main drain outlet becomes blocked. In such cases, with existing air-assisted water closets, undesirable backflow of waste from the common drain pipe into the waste pans 170 of one or more of the number of water closets can occur. In accordance with embodiments of the present disclosure, not only is backflow prevented by the waste valve of each of the number of water closets, but blockage of the building’s main drain becomes less likely. That is because only “active” water closets that are proceeding with a flush cycle (and are therefore pressurised) have their waste pans connected to the building’s drainage system, and therefore pressure transferred from the “active” water closets to the building’s drainage system cannot easily escape except by urging the waste out of the building, thereby assisting with clearance of any blockage. This is in contrast to existing systems, where all waste pans are always connected to the building’s drainage system, and thus pressure applied by an “active” water closet to a common drain pipe can escape into the waste pans of inactive water closets.Existing systems have attempted to alleviate such problems by providing a vertical vent pipe behind each waste pan assembly 170, however such solutions are less effective and require more installation space than the above-described solution that uses a waste valve assembly 150. The waste valve assembly 150 also assists with preventing odours from passing from the drainage system into the washroom in which the water closet is installed. To accommodate maintenance operations, such as dealing with a blocked drain, a maintenance mode is provided which is entered when an operator performs a specific operation, such as actuating a sensor or switch in a specific sequence. In said maintenance mode, the waste valve 1510 is opened and stays open until a reset operation is performed (which can be performed remotely via a command sent to the controller 160 via a network, or can be performed in response to an operator performing the or another specific operation such as actuating a sensor or switch in a specific sequence, or by closing the lid of the waste pan which is sensed by a lid state sensor). A variant of said maintenance mode can further be provided, in which during the maintenance mode the air pump 140 is operated for a predetermined period (e.g. 5 seconds) with the lid of the waste pan 171 closed, to attempt to clear a blockage in the waste pan and / or the common drain pipe.Referring to Figures 15 and 16, with reference also to Figure 13, a control method carried out by embodiments of the above-described controller 160 will now be described, which method is performed by an air-assisted water closet including embodiments described herein after having been installed and made ready for operation.Referring to Figure 15, step 200 comprises, conditional upon detecting a lid of a waste pan 170 of said air-assisted water closet being closed (i.e. changed from an open state to a closed state) by a user, causing the opening of a waste valve 1510 that controls flow between the waste pan 170 and a drainage system (e.g. a drainage system of a building) into which the waste pan 170 is intended to drain. Step 210 comprises commencing a combined air and water (air-assisted) flushing cycle that combines air and water flushing, as will be further described below with reference to Figure 16. Step 220 comprises, upon completion of the flushing cycle, causing the closing of the waste valve 1510. In this way, the waste pan 170 is isolated from the drainage system by the waste valve 1510, except when the lid of the waste pan 170 is closed and a flushing cycle is proceeding. Thus, if first and second air-assisted water closets are connected to a common drain, and the drainage system becomes blocked, flushing of the first air-assisted water closet (which will force pressurised air, water and waste into the common drain) will not result in pressurised air, water and waste being ejected from the common drain into the waste pan 170 of the second or other such water closets that are connected to the common drain.Optionally, the method described above with reference to Figure 15 further includes: responsive to detecting the opening of a lid of the waste pan 170 while the waste valve 150 is open, terminating any flushing cycle that is in progress and closing the waste valve 150. This provides a safety interlock, such that in normal operation the waste valve 150 is never open at the same time as the waste pan lid is open, preventing waste from being ejected into the washroom in which the water closet is installed. Optionally in such cases, an error is logged, but if the lid is closed again then the flushing cycle resumes.Optionally, the method described above with reference to Figure 15 further includes: upon commencing the flushing cycle, causing an optical indicator (such as a multi-colour LED) on a part of the air-assisted water closet (e.g. such as on a controller enclosure lid 162) to indicate that a flushing cycle is in progress (e.g. by flashing green), and upon completion of said flushing cycle causing said optical indicator to cease such indication. This can provide a convenient source of status indication to an operator or maintenance person, easing diagnosis of any apparent malfunction.Preferably, but optionally, the method described above with reference to Figure 15 can further comprise: upon at least one of commencing and completing the combined air and water flushing cycle, such as a time after the combined air and water flushing cycle, causing the sending of a message via a network to a computer server (e.g. cloud server 183), optionally via a gateway 184 or “hub”, said message containing data relating to said flushing cycle and / or any status of components of the water closet known by the controller 160, as well as containing an identification of the water closet and / or sub- components of the water closet. The sending of the message may be sent after each flush or sent at a predetermined data upload time, such as with other messages that may be queued for sending. Further, the method may include causing the sending of a message in response to or after an incomplete or failed combined air and water flushing cycle. This permits the cloud server to gather information regarding the number of flushing cycles performed by a given water closet, and any errors logged or components that are exhibiting impending or present failure. Said cloud server can then send one or more messages to appropriate operator personnel, notifying them of such status / errors, and / or automatically recommending maintenance / repair operations that should be performed, thereby improving system reliability and lowering operating costs.Referring to Figure 16, step 210 can further comprise the following steps. Step 300 comprises, upon commencement of a flushing cycle, causing a water pump of a water delivery device 135 to run for a first predetermined time period (e.g. 2 seconds), such that said water pump urges water through a siphon arrangement of the water delivery device 135, to the waste pan 170 from a water tank 1215 that has been pre-filled with a predetermined volume of water. Step 310 comprises, after the first predetermined time period, ceasing causing the water pump to run and / or causing the water pump to stop, whereupon water flow into the waste pan 170 continues by virtue of the action of the siphon in the water delivery device 135. Step 320 comprises causing an air pump 140 to run for a second predetermined time period (e.g. 2 seconds), such that said air pump 140 provides air to the waste pan 170. This has a further effect that the air pressure applied, by the air pump 140 to the waste pan 170, causes back-pressure in the water pipe that connects the water inlet 174 of the waste pan 170 to the water outlet connector 121 of the water tank assembly 120, which pressure causes the one-way valve 129 at the water outlet connector 121 to close, thereby stalling the water flow while the air pump 140 remains running. Step 330 comprises, after the second predetermined time period, ceasing causing the air pump 140 to run and / or causing the air pump 140 to stop, and then at step 340 waiting for a third predetermined time period (for example 2 seconds) to allow the air pump to stop (or “spool down”) and to allow the action of the siphon to resume and complete (thus refilling the pan with the remainder of the predetermined volume of water from the water tank 1215), whereupon the combined air and water flushing cycle is complete, and thus the waste valve150 is then closed (as in step 220). Once the air pump 140 has stopped, the aforementioned back-pressure dissipates so that the one-way valve 129 at the water outlet connector 121 re-opens, and water delivery then passively resumes from the water tank 1215 to the waste pan 170 via the siphon in the water delivery device 135, said siphon keeping the water flowing until the predetermined volume of water remaining in the water tank 1215 has been fully dispensed (thereby refilling the waste pan 170 with said remaining volume of water), at which point the inlet 138 of the water delivery device 135 becomes no- longer submerged by water. When the inlet 138 is no longer submerged by water (e.g. when the water level drops to the level of the castellations) then the siphon is broken. The controller 160 can then operate the solenoid water inlet valve 132 to refill the water tank 1215 up to the level at which the water level sensor 136 triggers, and the cistern assembly 100 is then ready for the next flush cycle.After a successful flush cycle, an internal flush counter is incremented and the status indicator LED 166 indicates (e.g. by fully illuminating green) a successful flush, both of which actions provide helpful indications for assisting with diagnosis of any faults. Thus, the controller 160 records data related to the flush cycles that are performed, and periodically sends said data to a server (e.g. cloud server 183) over a network. The controller 160, acting as a network node 185, may comprise circuitry to record the flush count and may be configured to send the flush count (and optionally fault information, battery / charging status) to a hub, such as gateway 184, periodically or after a predetermined number of flush cycles. The network nodes 185 may be configured to communicate with the hub or gateway 184 via a first network, such as a 433MHz radio frequency network. The hub, which may be located in the building in which the water closets / network nodes 185 are located, may collect data, such as flush count, from a plurality of network nodes 185. The hub or gateway 184 may be configured to send the data it collects from the controllers 160 / network nodes 185 to a server (e.g. cloud server 183) over a different, second network, such as a mobile network (GSM, 3G, LTE, 5G) or WiFi network. Preferably but optionally, the number of successful flushes is periodically sent as data in a message to the cloud server 183 for maintenance log purposes. Optionally, the controller 160 determines from said data that maintenance is required when a number of flush cycles exceeds a predetermined threshold (e.g. 200,000), and indicates that determination by sending a message to said server and / or by activating an optical indicator (e.g. status indicator LED 166) on a part of the air-assisted water closet (e.g. on the controller enclosure lid 162). Periodically sending data that is low priority (e.g. flush statistics) rather than instantly sending such data is advantageous because it reduces network usage. Conversely, error status is sent as soon as practicable, so as to reduce error reporting latency.Optionally, the entering of a maintenance condition is triggered when the controller detects that a user has operated a sensor (such as a sensor indicating whether the waste pan lid is open or closed) with a specific sequence. In said maintenance condition, which can be useful if it is required to unblock the building’s drain to which the waste pan 170 is connected, the waste valve 1510 is held in the open state, and remains so until a reset condition is detected by the controller (e.g. detection of the user closing the lid).Further optionally, a waste pan clearance operation (which can be considered to be a variant of the maintenance condition, or can be a separate mode) can be triggered by the controller 160 if the controller detects another specific sequence of user interactions with a sensor (e.g. a specific sequence of operation of the waste pan lid sensor), in which operation the controller 160 causes the waste valve 1510 to open and the air pump 140 to operate for a predetermined period (e.g. 5 seconds), with the aim of clearing any blockage in the waste pan 170. After the period of air pump 140 operation expires or if the lid is opened (in which case the air pump 140 is stopped immediately), the controller 160 closes the waste valve 1510.In accordance with some embodiments, prior to commencing a combined air and water flushing operation at step 210, as expanded in steps 300 to 330, certain self-checking and diagnostic checks can be made, which if passed permit the flushing cycle to proceed. By way of example:Optionally, upon causing the opening of the waste valve 1510, the controller 160 monitors an electrical current drawn by an electric motor 153 driving an actuator 154 of said waste valve 1510, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a predetermined threshold (e.g. +200% or - 50% of a normal current draw), then the controller 160 detects an error and aborts the combined air and water flushing cycle. Further optionally, the controller closes the waste valve 1510 after a delay of around 0.5 to 5 seconds (e.g. 2 seconds has been found to be satisfactory) from when the air pump 140 is turned off, the controller 160 measures the current drawn by the drive motor 153 of the waste valve assembly 150, and if the current reading is outside predetermined limits (e.g. +200% or -50% of normal) then an error is generated and the flush cycle (and / or a future flush cycle) is stopped.Preferably, prior to commencing the combined air and water flushing cycle, the controller 160 senses a water level in a water tank 1215 of said air-assisted water closet, and if too low or too high then the controller 160 detects an error and defers the flushing cycle. More specifically, if the water level is too low (i.e. the water level sensor 136 is not in the triggered state) the solenoid water inlet valve 132 is opened, and if the water level then remains too low for more than a predetermined length of time (e.g. 35 to 45 seconds, other time periods can be used as appropriate depending on the usual time taken for the water tank 1215 to fill from empty) then an error is generated and the flush cycle is aborted. By way of a more detailed example, the solenoid water inlet valve 132 is switched on after a delay of e.g. about 6 seconds (the delay allows the pan to be refilled with about 1 litre of water via a siphon effect and allows the siphon to break before the cistern is refilled – other delay periods can be used as appropriate depending on a usual length of time taken for the siphon to break). The solenoid water inlet valve 132 is switched off when the water level sensor 136 indicates that the water tank 1215 is full. If the water level sensor 136 has not detected the water tank 1215 being full after the aforementioned predetermined length of time then the solenoid water inlet valve 132 is turned off to prevent overflow, an error is generated, and the flush cycle stops. If the water level sensor 136 indicated that the water tank 1215 was full within the relevant predetermined length of time then the flush cycle is allowed to continue.Optionally, upon activating an air pump 140 for providing to the waste pan 170 the air of said combined air and water flushing cycle, the controller 160 measures an electrical current drawn by a motor 143 of said air pump 140, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a predetermined threshold (e.g. +200% or -50% of normal) then the controller 160 detects an error and aborts the flushing cycle. By way of example, the air pump can be run for 1 second during which time the current is measured.Optionally, upon activating a water pump in a water delivery device 135 for providing to the waste pan 170 the water of said combined air and water flushing cycle, the controller 160 measures an electrical current drawn by a motor of said water pump, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a threshold (e.g. +200% or -50% of normal) then the controller detects an error and aborts the combined air and water flushing cycle. By way of further example, the water pump can be run for 0.45 seconds for a 1.35L flush, after which the water pump motor current is measured, and if the reading is below 0.1 amps or above 4.5 amps then an error is generated, and the flush cycle is stopped.Optionally, upon activating a solenoid water inlet valve 132 for admitting water into the water tank 1215 of said air-assisted water closet, the controller 160 measures an electrical current drawn by said solenoid water inlet valve, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a threshold (e.g. +200% or -50% of normal) then detecting an error and deferring any combined air and water flushing cycle.Preferably but optionally, the controller 160 signals any error to a remote server such as cloud server 183 over a network, and / or indicates any such error on an optical indicator (such as status indicator LED 166) on a part of the air-assisted water closet (e.g. on the controller enclosure lid 162).Examples of errors and / or maintenance states optionally detectable and reportable by embodiments of the controller 160 follow below:No error, system ready for use: solid green LEDNo error, system is in a flush cycle: flashing green LED.Waste valve has exceeded a predetermined maximum number of cycles (e.g. 200,000) and needs maintenance (e.g. re-greasing): flashing red then green LED.Any of the following errors: flashing Red LED in a unique corresponding sequence (which sequence can be assigned in any arbitrary manner):o1 The toilet lid is open.o2 The water tank is empty.o3 The toilet pan is full or blocked.o4 The water pump is faulty.o5 The air pump is faulty.o6 The water level sensor failed to detect water.o7 The maximum reserved flushes on battery were reached.o8 The AGV is faulty.o9 The overflow float switch has been activated.Each controller 160 is preferably connected to a network, optionally via a wireless network modem, and constitutes a network node 185, e.g. an Internet-of-Things (IoT) node, for fault and status reporting. Status is reported (to a server 183) periodically to reduce network bandwidth requirements, while errors are reported (to the server 183) immediately for reduced latency. Each controller 160 has assigned to its network node 185 a unique address, and the address associated with each controller is mapped to a particular cubicle (or washroom). In this way, data from different controllers 160 can be mapped to the same cubicle, so that if the controller 160 is replaced then data collected by a first controller 160 for a given cubicle can be collated with data collected by a second controller 160 for the same cubicle, and thus data (which may be relevant to the maintenance state of the other components of the air-assisted water closet in that cubicle) can stay with the cubicle even if the controller is replaced.Turning to Figures 17 and 18, method steps executed by a server, e.g. cloud server 183, will now be described. At step 400, the server receives, over a network, data indicative of a number of flush operations performed by an air-assisted water closet. At step 410, based on said data, the server 183 determines whether or not a maintenance operation is due. At step 420, if a maintenance operation is due, the server 183 signals via a network (which may be the same network as in step 400 or may be a different network) an electronic message addressed to a maintenance operator 181, said electronic message containing data instructing the performance of said maintenance operation on a particular air-assisted water closet that is associated with the data.At step 500, a server (e.g. cloud server 183) receives, over a network, data indicative of an error state associated with an air-assisted water closet. At step 510, based on said data, the server 183 determines that a maintenance operation is required. At step 520, the server 183 signals via a network (which may be the same network as in step 500 or may be a different network) an electronic message addressed to a maintenance operator 181, said electronic message containing data instructing the performance of said maintenance operation on a particular air-assisted water closet that is associated with the data.In the methods shown in Figures 17 and 18, each one of a plurality of air-assisted water closets is associated with a respective unique node address, and each node address is associated with a respective physical location. Further, each node address or physical location is associated with addressing information by which an electronic message can be sent to a particular maintenance operator 181, and said addressing information is used to send, to said particular maintenance operator 181, the electronic message containing data instructing the performance of said maintenance operation. In other words, each water closet is associated with data held on the server 183 that indicates in which building 187, in which washroom 186, and in which cubicle a particular water closet is physically located, and each cubicle has a particular maintenance operator 181 associated with it, such that maintenance messages can be automatically sent by the server 183 to the maintenance operator 181, thereby resulting in reduced time before a fault is reported and remedied. This can not only reduce the time that a cubicle is out of service or in an unacceptable condition, but can also reduce the incidence and severity of further damage that may result from an initial fault being unreported or unremedied (e.g. water damage to a building resulting from a leaking cistern not being noticed for months, or vandalism caused by user dissatisfaction with the operating condition of a water closet).As shown in Figures 13 and 14, fault and maintenance information is collected by individual water closets at the level of individual cubicles or toilets (corresponding to network nodes 185), and as previously described this data is reported over a network to a server183. The controller 160 of each cistern assembly 100 includes a network node 185, and each network node 185 has an individual address. The network node 185 can either be plugged into the controller’s circuit board (e.g. via a connector on the controller’s circuit board or via a further auxiliary connector) or it can be built directly onto the controller’s circuit board. The network node 185 typically uses LoRa technology but can employ any suitable networking technology. The network node 185 transmits data when power is applied to the controller, and the data is sent to a gateway 184 (although network nodes 185 can also be configured to send data to other software applications such as asset tracking apps, which can be done in any suitable form such as MQQT, JSOT, HTML). A minimum of one gateway 184 is used per building, and some buildings 187 may need more than one gateway 184. The gateway 184 transmits data to a server (e.g. cloud server 183) which hosts a web- based application 190. This transmission is typically via a wireless modem using a SIM card, but it can be via other suitable technologies such as Wi-Fi and / or Ethernet. The server can be hosted locally or on services such as Azure, Google and / or AWS.In a database hosted at the server 183, the network node 185 (connected to the controller 160 of each water closet) is associated with a particular toilet / cubicle. The server183 can store further information detailing which washroom 186 each toilet / cubicle is located in, and also detailing which building 187 each washroom 186 is located in. Further, the server 183 can store information detailing individual proprietors (“customers 188”) with which each building 187 is associated. Furthermore, each building proprietor can be associated with a particular “partner 189” which may be an entity under which building proprietors are hierarchically grouped.As shown in Figures 19 to 24, a web application can be used to manage data from the water closets, and to manage the associations between the entities shown in Figure 14. The web application has multiple tiers of access and permissions, including Administrator level, Partner level, Customer level and Engineer level. The Administrator access level enables visibility off all data, and the ability to set up Partner pages 189, Customer pages 188, Buildings 187, Washrooms 186, Toilets (corresponding to network nodes 185) and Contacts 181. Thus, an administrator 1810 can set a link between any of the aforementioned entities, including setting up a link between each particular toilet / cubicle (corresponding to a particular network node 185) and a corresponding maintenance contact181. Thus, when a fault occurs it is logged in the system and a message can be automatically sent to the nominated maintenance contact 181 (for example this can be by email or text message). Cubicle to contact person mapping thus provides for maintenance / repair tasks to be notified to maintenance personnel in real time. Once maintenance has been performed and the fault rectified, the logged fault on the system can be cleared by logging into the web application and clearing the logged fault, at which time details of actions taken and / or components changed can be captured, which data can be subsequently analysed to improve fault tracking and prediction (e.g. if a particular component type or batch of components proves to have a higher than expected failure rate then appropriate rectification action can be taken, potentially including preventative maintenance). Reports can be generated at toilet, washroom, building, customer, partner and administrator level, viewing historic data relating to use (e.g. flush count), fault codes, component changes and account status, as applicable.Partners 189 only have permissions to view and update information relating to customers 188 who are linked to that partner, and customers 188 only have permissions to view and update information relating to their linked buildings 187. Engineer (e.g. maintenance personnel) access level allows visibility of all toilets linked to that Engineer. Figure 19 shows an example login page 191 of the web application 190. Figure 20 shows an example administrator level view 192 of the web application 190. Figure 21 shows an example partner level view 193 of the web application 190. Figure 22 shows an example customer level view 194 of the web application 190. Figure 23 shows an example building level view 195 of the web application 190. Figure 24 shows an example cubicle level view 196 of the web application 190. Such a reporting hierarchy provides for data to be kept confidential and not shared between different customers. Said hierarchy further provides for data on water savings and maintenance requirements to be reported to the relevant customer (e.g. building proprietor), such that data that is irrelevant to said customer is filtered out, thereby increasing the intelligibility and relevance of the data.In one or more examples, the server 183 and / or application 190 may be configured to identify trends the fault and maintenance information and / or usage information (e.g. flush count). The trends may be presented via a user dashboard presented by computing device(s) 182.Advantages and technical effects of aspects and embodiments, including those mentioned above, will be apparent to a skilled person from the foregoing description and from the Figures.It will be appreciated that the described methods can be carried out by one or more computers under control of one or more computer programs arranged to carry out said methods, said computer programs being stored in one or more memories and / or other kinds of computer-readable media. Figure 13 shows an example of a networked computer system 180 which can be used to implement the methods described herein, said computer system 180 comprising one or more cloud servers 183 incorporating one or more databases and hosting one or more web-based applications 190, one or more gateways 184, and one or more computing devices 182 (such as a PC, tablet and / or mobile device) for accessing said web application 190, wherein said cloud servers 183 and said computing devices 182 are communicatively coupled with each other by a computer network. Said computer network may comprise one or more of any kinds of computer network suitable for transmitting or communicating data, for example a local area network, a wide area network, a metropolitan area network, the Internet, a wireless communications network, a cable network, a digital broadcast network, a satellite communication network, a telephone network, etc. Each of the one or more gateways 184, cloud servers 183 and / or computing devices 182 may operate under control of one or more computer programs arranged to carry out all or a subset of method steps described with reference to any embodiment, thereby interacting with one another so as to collectively carry out the described method steps. Each of the one or more gateways 184, cloud servers 183 and / or computing devices182 may comprise a processor, memory, computer-readable storage medium, output interface, input interface and network interface, which can communicate with each other by virtue of one or more data buses. It will be appreciated that one or more of these features may be omitted, depending on the required functionality of said system. Said computer- readable storage medium may be any form of non-volatile and / or non-transitory data storage device such as a magnetic disk or optical disk, or other memory device such as RAM or ROM or Flash memory, and may store data, application program instructions according to one or more embodiments of the disclosure herein, and / or an operating system. The storage medium may be local to the processor, or may be accessed via a computer network or bus. The processor may be any apparatus capable of carrying out method steps according to embodiments of the invention, and may for example comprise a single data processing unit or multiple data processing units operating in parallel or in cooperation with each other, or may be implemented as a programmable logic array, graphics processor, or digital signal processor, or a combination thereof. The input interface is arranged to receive input from a user and provide it to the processor, and may comprise, for example, a mouse (or another pointing device), a keyboard and / or a touchscreen device. The output interface optionally provides a visual, tactile and / or audible output to a user of the system, under control of the processor.It will be appreciated that the above-described partitioning of functionality can be altered without affecting the functionality of the methods and systems, or their advantages / technical effects. The above-described functional partitioning is presented as an example in order that the invention can be understood, and is thus conceptual rather than limiting, the invention being defined by the appended claims. The skilled person will also appreciate that the described method steps may be combined or carried out in a different order without affecting the advantages and technical effects resulting from the invention as defined in the claims. It will be further appreciated that the described functionality can be implemented as hardware (for example, using field programmable gate arrays, ASICs or other hardware logic), firmware and / or software modules, or as a mixture of those modules. It will also be appreciated that, a computer-readable storage medium and / or a transmission medium (such as a communications signal, data broadcast, communications link between two or more computers, etc.), carrying a computer program arranged to implement one or more aspects of the invention, may embody aspects of the invention. The term “computer program,” as used herein, refers to a sequence of instructions designed for execution on a computer system, and may include source or object code, one or more functions, modules, executable applications, applets, servlets, libraries, and / or other instructions that are executable by a computer processor.Various modifications may be made to the preferred embodiments described herein without departing from the scope of the invention as defined by the accompanying claims.Many combinations, modifications, or alterations to the features of the above embodiments will be readily apparent and are intended to form part of the disclosure. Any of the features described specifically relating to one embodiment or example may be used in any other embodiment by making appropriate changes as apparent in the light of the above disclosure. CLAIMS 1.A cistern assembly of an air-assisted water closet, the cistern assembly comprising:a mount comprising:a first generally planar portion arranged in a first plane, the first portion having a front side, a rear side opposite the front side, and one or more first mounting features for fixing the rear side to a wall;one or more second mounting features for mounting a water tank to the mount; and one or more third mounting features for mounting an air pump to the mount; andat least one of a corresponding air pump and a corresponding water tank, arranged for mounting to the mount. 2.The cistern assembly of claim 1 further comprising a second generally planar portion arranged in a second plane, the second plane being parallel to and spaced apart from the first plane in a direction away from the rear side and towards the front side, wherein the second portion comprises an opening therethrough for air to pass through, and wherein the third mounting features and the opening are arranged relative to each other such that when an air pump is mounted to the second portion using the third mounting features, the opening is arranged to admit air to at least a portion of the air pump. 3.The cistern assembly of claim 2, wherein the second portion further comprises one or more alignment features for aligning a cover of said air pump with the second portion when said air pump is mounted to the second portion. 4.The cistern assembly of any preceding claim wherein the one or more second mounting features comprise at least one protrusion arranged for engagement with a corresponding recess of a corresponding water tank, and / or at least one recess arranged for engagement with a corresponding protrusion of said corresponding water tank. 5.The cistern assembly of claim 2, wherein the second portion is configured to be spaced from the wall when the mount is mounted to the wall. 6.The cistern assembly of any preceding claim, comprising said air pump, wherein the air pump is a centrifugal type or a vane type. 7.The cistern assembly of any preceding claim, comprising said air pump, wherein the air pump comprises an electric motor, a cover, and noise reducing material provided between the motor and the cover, wherein optionally the noise reducing material comprises a foam material. 8.The cistern assembly of any preceding claim, comprising said air pump, wherein the air pump comprises a pump body and an electric pump motor, wherein the pump motor is attached to the pump body via a number of vibration insulators. 9.The cistern assembly of any preceding claim, comprising said water tank, wherein the water tank comprises a water tank assembly including a subframe component of the water tank assembly, said subframe component being arranged to be removably mountable inside a water tank of said water tank assembly, by virtue of the subframe component comprising an engagement portion for removable engagement with said water tank, wherein said subframe component is provided with respective attachment positions for a plurality of further components of said water tank assembly. 10.The cistern assembly of claim 9, the subframe component comprising two or more of:a first attachment position for attaching a solenoid water inlet valve; a second attachment position for attaching a water delivery device; a third attachment position for attaching a water level sensor; and a fourth attachment position for attaching a water overflow sensor. 11.The cistern assembly of claim 10, comprising the first attachment position, and further comprising a water inlet valve removably attachable to the first attachment position, wherein the water inlet valve comprises a water inlet, the water inlet comprising a support bracket removably attachable thereto. 12.The cistern assembly of claim 9, comprising the second attachment position, and further comprising a water delivery device removably attachable to the second attachment position, said water delivery device comprising a water delivery tube arranged for removable connection with a water outlet connector of a water tank to which said subframe component is arranged to be fitted. 13.The cistern assembly of claim 12, comprising a bayonet-type fitting at the second attachment position for securing the water delivery device by virtue of a corresponding portion on the water delivery device. 14.The cistern assembly of claim 12 or claim 13, wherein the water delivery device comprises a pump and a siphon. 15.The cistern assembly of any of claims 12 to 14, wherein the water delivery device has a body, with an inlet at a lower part of the body, wherein the second attachment position is located relative to the engagement portion such that when the subframe component is mounted in said water tank and the water delivery device is mounted to the subframe component, the inlet of the water delivery device is positioned adjacent to the bottom of the tank while allowing water ingress from the tank into the inlet of the water delivery device. 16.The cistern assembly of any of claims 12 to 15, wherein the water delivery device comprises a number of side openings at least partly around a perimeter of the lower part of the body, and optionally wherein the side openings are in the form of castellations. 17.The cistern assembly of any of claims 10 to 16, comprising the third attachment position, and further comprising a water level sensor removably attachable to the third attachment position, the water level sensor arranged for sensing, by virtue of a relative position of the water level sensor versus the engagement portion, when a water level inside a water tank to which said subframe component is arranged to be removable mountable has reached a first predetermined level. 18.The cistern assembly of any of claims 10 to 17, comprising the fourth attachment position, and further comprising a water overflow sensor removably attachable to the fourth attachment position, the water overflow sensor arranged for sensing, by virtue of a relative position of the water overflow sensor versus the engagement portion, when a water level inside a water tank to which said subframe component is arranged to be fitted has exceeded a second predetermined level. 19.The cistern assembly of any one of claims 9 to 18, comprising a primary water containment volume, and having a water outlet connector through a wall of a lower portion of the primary water containment volume, said water outlet connector arranged for removable connection inside the water tank with a water delivery tube of a water delivery device. 20.The cistern assembly of claim 19, wherein the water outlet connector comprises a first one-way valve allowing egress of water from the water delivery tube to a first external pipe connection of the water outlet connector, and preventing ingress of fluid from the first external pipe connection. 21.The cistern assembly of any one of claims 9 to 20 , further comprising a float indicator mounted through the water tank and arranged to indicate an under-filled condition of the water tank by virtue of buoyancy. 22.The cistern assembly of any one of claims 9 to 21, further comprising an overflow weir separating an overflow volume of the water tank from a primary water containment volume of the water tank, and further comprising an overflow outlet through a wall of a lower portion of the overflow volume. 23.The cistern assembly of claim 22, wherein the overflow outlet comprises a second one-way valve allowing egress of water from the overflow volume to a second external pipe connection of the overflow outlet, and preventing ingress of fluid from the second external pipe connection. 24.The cistern assembly of any one of claims 9 to 23, further comprising an auxiliary overflow opening through a wall of the water tank, wherein a lower edge of the auxiliary overflow opening is arranged such that in use it is positioned higher than a top edge of the overflow weir and is positioned lower than an opening of a water inlet spout of the water tank assembly. 25.The cistern assembly of any one of claims 9 to 24, further comprising one or more mounting features, wherein optionally said mounting features comprise at least one recess arranged for engagement with a corresponding protrusion of a corresponding mount, and / or at least one protrusion arranged for engagement with a corresponding recess of a corresponding mount. 26.The cistern assembly of any one of claims 9 to 25, wherein the water tank comprises an attachment position for a removably mountable support bracket for supporting a water inlet pipe connection. 27.The cistern assembly of any one of claims 9 to 26, further comprising a cable tray at an upper portion of the water tank, for managing cables of electrical components that in use are mounted inside the water tank assembly. 28.The cistern assembly of any one of claims 22 to 27, additionally provided with a 2-to1 connector pipe arranged for joining the first external pipe connection and the second external pipe connection to provide a combined water outlet. 29.The cistern assembly of claim 28, wherein the pipe connections of the 2-to-1 connector pipe are quick-release connections each comprising an o-ring seal and securing means, and optionally wherein the securing means is a retaining clip that is selectably engageable with both said connector pipe and said external pipe connections. 30. The cistern assembly of claim 2, wherein the second generally planar portion comprises a part of the mount configured to be spaced away from the wall upon which the mount is fixed. 31.A waste valve assembly for an air-assisted water closet, the waste valve assembly comprising:a valve body having a selectively closable opening therethrough;a valve shutter located in the valve body and movable between at least two positions, wherein in a first position the opening is at least partially open, and in a second position the opening is closed;an actuator connectable to the valve shutter for moving the valve shutter between the first position and the second position; anda chassis,wherein the chassis comprises mounting positions for the valve body and the actuator, and wherein a guard hoop extends from the chassis and at least partially surrounds the actuator mounting position to define an area inboard of the guard hoop within which a whole range of movement of the actuator is accommodated. 32.The waste valve assembly of claim 31, further comprising an electric motor arranged for driving the actuator and thereby moving the shutter between the first and second positions, and optionally wherein the actuator is a linear actuator and the valve body and valve shutter are arranged as a gate valve configuration. 33.The waste valve assembly of claim 31 or 32, further comprising a lubrication fitting for a maintenance operator to add lubricant to the waste valve assembly when the waste valve assembly is in-situ. 34.The waste valve assembly of any of claims 31 to 33, wherein the valve body comprises a pipe fitting on at least one of an inlet and an outlet side of the waste valve assembly, and optionally wherein the pipe fitting comprises at least one of a collar and a flange. 35.A method executed by a controller of an air-assisted water closet, the method comprising the following steps:conditional upon a lid of a waste pan of the air-assisted water closet being closed, causing the opening of a waste valve that controls flow between the waste pan and a drainage system into which the waste pan is intended to drain;commencing a combined air and water flushing cycle; andupon completion of the combined air and water flushing cycle, causing the closing of said waste valve. 36.The method of claim 35, further comprising: responsive to detecting the opening of the waste pan lid while the waste valve is open, terminating any flushing cycle that is in progress, and causing the closing of the waste valve. 37.The method of any of claims 35 to 36, further comprising: upon commencing the combined air and water flushing cycle, causing an optical indicator on a part of the air- assisted water closet to indicate that a flushing cycle is in progress; and upon completion of the combined air and water flushing cycle, causing said optical indicator to cease indicating that a flushing cycle is in progress. 38.The method of any of claims 35 to 37, further comprising: upon at least one of commencing the combined air and water flushing cycle and completing the combined air and water flushing cycle, causing the sending of a message to a computer server, said message containing data relating to said flushing cycle. 39.The method of any of claims 35 to 38, wherein the combined air and water flushing cycle further comprises the following steps:upon commencement of a combined air and water flushing cycle, causing a water pump of a water delivery device to run for a first predetermined time period, such that said water pump urges water through a siphon arrangement of the water delivery device, to the waste pan from a water tank pre-filled with a predetermined volume of water;after the first predetermined time period, causing the water pump to stop, whereupon water flow into the waste pan can continue by virtue of action of said siphon;causing an air pump to run for a second predetermined time period, such that said air pump provides air to the waste pan, and such that water flow through said siphon is stalled by resulting back-pressure from the waste pan to the water tank;after the second predetermined time period, ceasing causing the air pump to run;andwaiting for a third predetermined time period to allow the air pump to stop and toallow action of the siphon to resume and complete, constituting completion of the combined air and water flushing cycle. 40.The method of any of claims 35 to 39, further comprising triggering a maintenance condition wherein the waste valve is caused to open and to remain open until an reset operation is performed by a user, said maintenance condition being triggered by detecting a specific sequence of user-operations of a sensor, and optionally wherein the maintenance condition further comprises activating the air pump for a predetermined time period when the lid of the waste pan is closed. 41.The method of any of claims 35 to 40, further comprising: upon causing the opening of said waste valve, monitoring an electrical current drawn by an electric motor driving an actuator of said waste valve, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a predetermined threshold, then detecting an error and aborting the combined air and water flushing cycle. 42.The method of any of claims 35 to 41, further comprising: prior to commencing the combined air and water flushing cycle, sensing a water level in a water tank of said air- assisted water closet, and if too low or too high then detecting an error and optionally deferring any combined air and water flushing cycle. 43.The method of any of claims 35 to 42, further comprising: upon activating an air pump for providing to the waste pan the air of said combined air and water flushing cycle, measuring an electrical current drawn by a motor of said air pump, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a predetermined threshold then detecting an error and optionally aborting the combined air and water flushing cycle. 44.The method of any of claims 35 to 43, further comprising: upon activating a water pump for providing to the waste pan the water of said combined air and water flushing cycle, measuring an electrical current drawn by a motor of said water pump, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a threshold then detecting an error and optionally aborting the combined air and water flushing cycle. 45.The method of any of claims 35 to 44, further comprising: upon activating a solenoid water inlet valve for admitting water into a water tank of said air-assisted water closet, measuring an electrical current drawn by said solenoid water inlet valve, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a threshold then detecting an error and optionally deferring any combined air and water flushing cycle. 46.The method of any of claims 35 to 45, further comprising: signalling any detected errors to a remote server over a network, and / or indicating any such errors on an optical indicator on a part of the air-assisted water closet. 47.The method of any of claims 35 to 46, further comprising: recording data related to the flush cycles that are performed, and periodically sending said data to a server over a network. 48.The method of claim 47, further comprising: determining from said data that maintenance is required when a number of flush cycles exceeds a predetermined threshold, and indicating that determination by sending a message to said server and / or by activating an optical indicator on a part of the air-assisted water closet. 49.A controller unit arranged to carry out the method steps as defined in any of claims 35 to 48. 50.The controller unit of claim 49, further comprising an optical indicator that is arranged to indicate at least one of (i) when a flush operation is in progress, and (ii) when a state requiring attention exists such as a detected error or a determined maintenance requirement. 51.The controller unit of any of claims 49 to 50, further comprising a housing for mounting a circuit assembly, wherein the circuit assembly comprises at least one processor arranged for carrying out the method steps, and the housing is arranged to fit directly on top of the water tank assembly of any of claims 19 to 30 thereby forming a lid of said water tank assembly. 52.The controller unit of any of claims 49 to 51, further comprising a network interface configured for communicating status of the controller unit to a data server across a network, and optionally wherein the network interface is a wireless network interface. 53.A computer-implemented method comprising the following steps:receiving, over a network, data indicative of a number of flush operations performed by an air-assisted water closet;based on said data, determining whether or not a maintenance operation is due;andif a maintenance operation is due, signalling via a network, an electronic messageaddressed to a maintenance operator, said electronic message containing data instructing the performance of said maintenance operation on a particular air-assisted water closet associated with the data. 54.A computer-implemented method comprising the following steps:receiving, over a network, data indicative of an error state associated with an air- assisted water closet;based on said data, determining that a maintenance operation is required; and signalling via a network, an electronic message addressed to a maintenanceoperator, said electronic message containing data instructing the performance of said maintenance operation on a particular air-assisted water closet associated with the data. 55.The method of claim 53 or claim 54, wherein each one of a plurality of air-assisted water closets is associated with a respective unique node address, and each node address is associated with a respective physical location. 56.The method of any of claims 53 to 55, wherein each node address or physical location is associated with addressing information by which an electronic message can be sent to a particular maintenance operator, and wherein said addressing information is used to send, to said particular maintenance operator, the electronic message containing data instructing the performance of said maintenance operation. 57.A computer program product comprising machine-readable instructions that when executed by one or more processors causes the one or more processors to carry out the method of any of claims 35 to 48 and / or claims 53 to 56.  58.A computer-readable medium storing machine-readable instructions that when executed by one or more processors causes the one or more processors to carry out the method of any of claims 35 to 48 and / or claims 53 to 56. 59.An air-assisted water closet including a cistern assembly as defined in any of claims 1 to 30, a waste valve assembly as defined in any of claims 31 to 34, a controller unit as defined in any of claims 49 to 52, a computer program product as defined in claim 57 and / or a computer-readable medium as defined in claim 58.  ABSTRACT A cistern assembly, including a mount, of an air-assisted water closet, the mount comprising: a first generally planar portion arranged in a first plane, the first portion having a front side, a rear side opposite the front side, and one or more first mounting features for fixing the rear side to a wall; one or more second mounting features for mounting a water tank to the mount; and one or more third mounting features for mounting an air pump to the mount. Figure 3 

Claims

1.A cistern assembly of an air-assisted water closet, the cistern assembly comprising:a mount comprising:a first generally planar portion arranged in a first plane, the first portion having a front side, a rear side opposite the front side, and one or more first mounting features for fixing the rear side to a wall;one or more second mounting features for mounting a water tank to the mount; and one or more third mounting features for mounting an air pump to the mount; andat least one of a corresponding air pump and a corresponding water tank, arranged for mounting to the mount. 2.The cistern assembly of claim 1 further comprising a second generally planar portion arranged in a second plane, the second plane being parallel to and spaced apart from the first plane in a direction away from the rear side and towards the front side, wherein the second portion comprises an opening therethrough for air to pass through, and wherein the third mounting features and the opening are arranged relative to each other such that when an air pump is mounted to the second portion using the third mounting features, the opening is arranged to admit air to at least a portion of the air pump. 3.The cistern assembly of claim 2, wherein the second portion further comprises one or more alignment features for aligning a cover of said air pump with the second portion when said air pump is mounted to the second portion. 4.The cistern assembly of any preceding claim wherein the one or more second mounting features comprise at least one protrusion arranged for engagement with a corresponding recess of a corresponding water tank, and / or at least one recess arranged for engagement with a corresponding protrusion of said corresponding water tank. 5.The cistern assembly of claim 2, wherein the second portion is configured to be spaced from the wall when the mount is mounted to the wall. 6.The cistern assembly of any preceding claim, comprising said air pump, wherein the air pump is a centrifugal type or a vane type. 7.The cistern assembly of any preceding claim, comprising said air pump, wherein the air pump comprises an electric motor, a cover, and noise reducing material provided between the motor and the cover, wherein optionally the noise reducing material comprises a foam material. 8.The cistern assembly of any preceding claim, comprising said air pump, wherein the air pump comprises a pump body and an electric pump motor, wherein the pump motor is attached to the pump body via a number of vibration insulators.9.The cistern assembly of any preceding claim, comprising said water tank, wherein the water tank comprises a water tank assembly including a subframe component of the water tank assembly, said subframe component being arranged to be removably mountable inside a water tank of said water tank assembly, by virtue of the subframe component comprising an engagement portion for removable engagement with said water tank, wherein said subframe component is provided with respective attachment positions for a plurality of further components of said water tank assembly. 10.The cistern assembly of claim 9, the subframe component comprising two or more of:a first attachment position for attaching a solenoid water inlet valve; a second attachment position for attaching a water delivery device; a third attachment position for attaching a water level sensor; and a fourth attachment position for attaching a water overflow sensor. 11.The cistern assembly of claim 10, comprising the first attachment position, and further comprising a water inlet valve removably attachable to the first attachment position, wherein the water inlet valve comprises a water inlet, the water inlet comprising a support bracket removably attachable thereto. 12.The cistern assembly of claim 9, comprising the second attachment position, and further comprising a water delivery device removably attachable to the second attachment position, said water delivery device comprising a water delivery tube arranged for removable connection with a water outlet connector of a water tank to which said subframe component is arranged to be fitted. 13.The cistern assembly of claim 12, comprising a bayonet-type fitting at the second attachment position for securing the water delivery device by virtue of a corresponding portion on the water delivery device. 14.The cistern assembly of claim 12 or claim 13, wherein the water delivery device comprises a pump and a siphon. 15.The cistern assembly of any of claims 12 to 14, wherein the water delivery device has a body, with an inlet at a lower part of the body, wherein the second attachment position is located relative to the engagement portion such that when the subframe component is mounted in said water tank and the water delivery device is mounted to the subframe component, the inlet of the water delivery device is positioned adjacent to the bottom of the tank while allowing water ingress from the tank into the inlet of the water delivery device. 16.The cistern assembly of any of claims 12 to 15, wherein the water delivery device comprises a number of side openings at least partly around a perimeter of the lower part of the body, and optionally wherein the side openings are in the form of castellations. 17.The cistern assembly of any of claims 10 to 16, comprising the third attachment position, and further comprising a water level sensor removably attachable to the third attachment position, the water level sensor arranged for sensing, by virtue of a relative position of the water level sensor versus the engagement portion, when a water level inside a water tank to which said subframe component is arranged to be removable mountable has reached a first predetermined level. 18.The cistern assembly of any of claims 10 to 17, comprising the fourth attachment position, and further comprising a water overflow sensor removably attachable to the fourth attachment position, the water overflow sensor arranged for sensing, by virtue of a relative position of the water overflow sensor versus the engagement portion, when a water level inside a water tank to which said subframe component is arranged to be fitted has exceeded a second predetermined level. 19.The cistern assembly of any one of claims 9 to 18, comprising a primary water containment volume, and having a water outlet connector through a wall of a lower portion of the primary water containment volume, said water outlet connector arranged for removable connection inside the water tank with a water delivery tube of a water delivery device. 20.The cistern assembly of claim 19, wherein the water outlet connector comprises a first one-way valve allowing egress of water from the water delivery tube to a first external pipe connection of the water outlet connector, and preventing ingress of fluid from the first external pipe connection.21.The cistern assembly of any one of claims 9 to 20 , further comprising a float indicator mounted through the water tank and arranged to indicate an under-filled condition of the water tank by virtue of buoyancy. 22.The cistern assembly of any one of claims 9 to 21, further comprising an overflow weir separating an overflow volume of the water tank from a primary water containment volume of the water tank, and further comprising an overflow outlet through a wall of a lower portion of the overflow volume. 23.The cistern assembly of claim 22, wherein the overflow outlet comprises a second one-way valve allowing egress of water from the overflow volume to a second external pipe connection of the overflow outlet, and preventing ingress of fluid from the second external pipe connection. 24.The cistern assembly of any one of claims 9 to 23, further comprising an auxiliary overflow opening through a wall of the water tank, wherein a lower edge of the auxiliary overflow opening is arranged such that in use it is positioned higher than a top edge of the overflow weir and is positioned lower than an opening of a water inlet spout of the water tank assembly. 25.The cistern assembly of any one of claims 9 to 24, further comprising one or more mounting features, wherein optionally said mounting features comprise at least one recess arranged for engagement with a corresponding protrusion of a corresponding mount, and / or at least one protrusion arranged for engagement with a corresponding recess of a corresponding mount. 26.The cistern assembly of any one of claims 9 to 25, wherein the water tank comprises an attachment position for a removably mountable support bracket for supporting a water inlet pipe connection. 27.The cistern assembly of any one of claims 9 to 26, further comprising a cable tray at an upper portion of the water tank, for managing cables of electrical components that in use are mounted inside the water tank assembly. 28.The cistern assembly of any one of claims 22 to 27, additionally provided with a 2-to1 connector pipe arranged for joining the first external pipe connection and the second external pipe connection to provide a combined water outlet. 29.The cistern assembly of claim 28, wherein the pipe connections of the 2-to-1 connector pipe are quick-release connections each comprising an o-ring seal and securing means, and optionally wherein the securing means is a retaining clip that is selectably engageable with both said connector pipe and said external pipe connections. 30. The cistern assembly of claim 2, wherein the second generally planar portion comprises a part of the mount configured to be spaced away from the wall upon which the mount is fixed. 31.A waste valve assembly for an air-assisted water closet, the waste valve assembly comprising:a valve body having a selectively closable opening therethrough;a valve shutter located in the valve body and movable between at least two positions, wherein in a first position the opening is at least partially open, and in a second position the opening is closed;an actuator connectable to the valve shutter for moving the valve shutter between the first position and the second position; anda chassis,wherein the chassis comprises mounting positions for the valve body and the actuator, and wherein a guard hoop extends from the chassis and at least partially surrounds the actuator mounting position to define an area inboard of the guard hoop within which a whole range of movement of the actuator is accommodated. 32.The waste valve assembly of claim 31, further comprising an electric motor arranged for driving the actuator and thereby moving the shutter between the first and second positions, and optionally wherein the actuator is a linear actuator and the valve body and valve shutter are arranged as a gate valve configuration. 33.The waste valve assembly of claim 31 or 32, further comprising a lubrication fitting for a maintenance operator to add lubricant to the waste valve assembly when the waste valve assembly is in-situ. 34.The waste valve assembly of any of claims 31 to 33, wherein the valve body comprises a pipe fitting on at least one of an inlet and an outlet side of the waste valve assembly, and optionally wherein the pipe fitting comprises at least one of a collar and a flange. 35.A method executed by a controller of an air-assisted water closet, the method comprising the following steps:conditional upon a lid of a waste pan of the air-assisted water closet being closed, causing the opening of a waste valve that controls flow between the waste pan and a drainage system into which the waste pan is intended to drain;commencing a combined air and water flushing cycle; andupon completion of the combined air and water flushing cycle, causing the closing of said waste valve. 36.The method of claim 35, further comprising: responsive to detecting the opening of the waste pan lid while the waste valve is open, terminating any flushing cycle that is in progress, and causing the closing of the waste valve. 37.The method of any of claims 35 to 36, further comprising: upon commencing the combined air and water flushing cycle, causing an optical indicator on a part of the air- assisted water closet to indicate that a flushing cycle is in progress; and upon completion of the combined air and water flushing cycle, causing said optical indicator to cease indicating that a flushing cycle is in progress. 38.The method of any of claims 35 to 37, further comprising: upon at least one of commencing the combined air and water flushing cycle and completing the combined air and water flushing cycle, causing the sending of a message to a computer server, said message containing data relating to said flushing cycle. 39.The method of any of claims 35 to 38, wherein the combined air and water flushing cycle further comprises the following steps:upon commencement of a combined air and water flushing cycle, causing a water pump of a water delivery device to run for a first predetermined time period, such that said water pump urges water through a siphon arrangement of the water delivery device, to the waste pan from a water tank pre-filled with a predetermined volume of water;after the first predetermined time period, causing the water pump to stop, whereupon water flow into the waste pan can continue by virtue of action of said siphon;causing an air pump to run for a second predetermined time period, such that said air pump provides air to the waste pan, and such that water flow through said siphon is stalled by resulting back-pressure from the waste pan to the water tank;after the second predetermined time period, ceasing causing the air pump to run;andwaiting for a third predetermined time period to allow the air pump to stop and toallow action of the siphon to resume and complete, constituting completion of the combined air and water flushing cycle. 40.The method of any of claims 35 to 39, further comprising triggering a maintenance condition wherein the waste valve is caused to open and to remain open until an reset operation is performed by a user, said maintenance condition being triggered by detecting a specific sequence of user-operations of a sensor, and optionally wherein the maintenance condition further comprises activating the air pump for a predetermined time period when the lid of the waste pan is closed. 41.The method of any of claims 35 to 40, further comprising: upon causing the opening of said waste valve, monitoring an electrical current drawn by an electric motor driving an actuator of said waste valve, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a predetermined threshold, then detecting an error and aborting the combined air and water flushing cycle. 42.The method of any of claims 35 to 41, further comprising: prior to commencing the combined air and water flushing cycle, sensing a water level in a water tank of said air- assisted water closet, and if too low or too high then detecting an error and optionally deferring any combined air and water flushing cycle. 43.The method of any of claims 35 to 42, further comprising: upon activating an air pump for providing to the waste pan the air of said combined air and water flushing cycle, measuring an electrical current drawn by a motor of said air pump, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a predetermined threshold then detecting an error and optionally aborting the combined air and water flushing cycle. 44.The method of any of claims 35 to 43, further comprising: upon activating a water pump for providing to the waste pan the water of said combined air and water flushing cycle, measuring an electrical current drawn by a motor of said water pump, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a threshold then detecting an error and optionally aborting the combined air and water flushing cycle. 45.The method of any of claims 35 to 44, further comprising: upon activating a solenoid water inlet valve for admitting water into a water tank of said air-assisted water closet, measuring an electrical current drawn by said solenoid water inlet valve, and if a magnitude of difference between the electrical current drawn and an expected electrical current draw is above a threshold then detecting an error and optionally deferring any combined air and water flushing cycle. 46.The method of any of claims 35 to 45, further comprising: signalling any detected errors to a remote server over a network, and / or indicating any such errors on an optical indicator on a part of the air-assisted water closet. 47.The method of any of claims 35 to 46, further comprising: recording data related to the flush cycles that are performed, and periodically sending said data to a server over a network. 48.The method of claim 47, further comprising: determining from said data that maintenance is required when a number of flush cycles exceeds a predetermined threshold, and indicating that determination by sending a message to said server and / or by activating an optical indicator on a part of the air-assisted water closet. 49.A controller unit arranged to carry out the method steps as defined in any of claims 35 to 48.50.The controller unit of claim 49, further comprising an optical indicator that is arranged to indicate at least one of (i) when a flush operation is in progress, and (ii) when a state requiring attention exists such as a detected error or a determined maintenance requirement. 51.The controller unit of any of claims 49 to 50, further comprising a housing for mounting a circuit assembly, wherein the circuit assembly comprises at least one processor arranged for carrying out the method steps, and the housing is arranged to fit directly on top of the water tank assembly of any of claims 19 to 30 thereby forming a lid of said water tank assembly. 52.The controller unit of any of claims 49 to 51, further comprising a network interface configured for communicating status of the controller unit to a data server across a network, and optionally wherein the network interface is a wireless network interface. 53.A computer-implemented method comprising the following steps:receiving, over a network, data indicative of a number of flush operations performed by an air-assisted water closet;based on said data, determining whether or not a maintenance operation is due;andif a maintenance operation is due, signalling via a network, an electronic messageaddressed to a maintenance operator, said electronic message containing data instructing the performance of said maintenance operation on a particular air-assisted water closet associated with the data. 54.A computer-implemented method comprising the following steps:receiving, over a network, data indicative of an error state associated with an air- assisted water closet;based on said data, determining that a maintenance operation is required; and signalling via a network, an electronic message addressed to a maintenanceoperator, said electronic message containing data instructing the performance of said maintenance operation on a particular air-assisted water closet associated with the data. 55.The method of claim 53 or claim 54, wherein each one of a plurality of air-assisted water closets is associated with a respective unique node address, and each node address is associated with a respective physical location. 56.The method of any of claims 53 to 55, wherein each node address or physical location is associated with addressing information by which an electronic message can be sent to a particular maintenance operator, and wherein said addressing information is used to send, to said particular maintenance operator, the electronic message containing data instructing the performance of said maintenance operation. 57.A computer program product comprising machine-readable instructions that when executed by one or more processors causes the one or more processors to carry out the method of any of claims 35 to 48 and / or claims 53 to 56.  58.A computer-readable medium storing machine-readable instructions that when executed by one or more processors causes the one or more processors to carry out the method of any of claims 35 to 48 and / or claims 53 to 56. 59.An air-assisted water closet including a cistern assembly as defined in any of claims 1 to 30, a waste valve assembly as defined in any of claims 31 to 34, a controller unit as defined in any of claims 49 to 52, a computer program product as defined in claim 57 and / or a computer-readable medium as defined in claim 58. 

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