MVHR STALE AIR SUPPLY
TECHNICAL FIELD
[0001] The present invention relates to the supply of stale air to a Mechanical Ventilation with Heat Recovery, MVHR, unit. Particularly, the present invention relates to the selective receipt of stale air from first and second locations within a building. The present invention further relates to a stale air valve mechanism, separate from an MVHR unit, that selectively receives stale air from first and second locations within a building. The present invention further relates to corresponding ventilation methods.
BACKGROUND
[0002] A building ventilation system is designed to supply fresh air to the building and to expel stale air. An MVHR system is a type of building ventilation system. An MVHR system comprises an MVHR unit, which includes a heat exchanger, and appropriate ventilation ducting for fresh air and stale air. An MVHR system is designed to provide controlled, efficient ventilation while recovering the heat from outgoing stale air to minimise heat loss from the building (or heat gain in the event that the ambient temperature outside the building exceeds the desired temperature inside the building). An MVHR system may also enhance indoor air quality, and reduce energy consumption for heating and cooling. A fresh air intake brings in fresh outdoor air from outside the building. Stale indoor air is simultaneously extracted from the building. Both the incoming fresh air and outgoing stale air pass through a heat exchanger. The heat exchanger allows the transfer of heat between the two air streams without mixing them. During the heat exchange process, the heat from the warm outgoing air is transferred to the cooler incoming air, pre-warming it in the winter. In the summer, the process can be reversed to provide cooling of incoming fresh air. The pre-conditioned fresh air is then distributed to various living spaces within the building through a network of ducts and vents. Before entering the living spaces, the fresh air typically goes through filters to remove pollutants, allergens, and particles. Further powered heating, cooling, or conditioning of fresh air may be provided. The extracted stale air is usually expelled to the outside, along with moisture, odours, and other pollutants. MVHR systems are equipped with controls to regulate airflow, temperature, indoor pollution, and humidity levels according to user preferences.
[0003] For regions of a building that may be periodically humid, including bathrooms and kitchens, particular in a domestic property, extractor fans may be provided to exhaust the humid air from the building. An extractor fan does not typically include heat recovery and so can be inefficient, for instance if warm internal air is replaced by cooler fresh air that must be separately cooled.
[0004] It is an aim of certain examples of the present invention to solve, mitigate or obviate, at least partly, at least one of the problems and/or disadvantages associated with the prior art. Certain examples aim to provide at least one of the advantages described below.
BRIEF SUMMARY OF THE INVENTION
[0005] According to a first aspect of the present invention there is provided a Mechanical Ventilation with Heat Recovery, MVHR, unit comprising: a fresh air inlet to receive fresh air and a fresh air outlet to discharge fresh air, the fresh air outlet being coupled to the fresh air inlet through a fresh air duct; a stale air inlet to receive stale air and a stale air outlet to discharge stale air, the stale air outlet being coupled to the stale air inlet through a stale air duct; and a heat exchanger configured so that heat can be transferred between stale air in the stale air duct and fresh air in the fresh air duct; wherein the stale air inlet includes a stale air valve configured in use to selectively receive stale air from first and second stale air supply ducts.
[0006] An advantage of the first aspect of the invention is that the MVHR unit is able to selectively receive stale air from different supply ducts and hence from different regions of a building according to where it is most advantageous to source the stale air. In an example of a normal operation mode, it may be that stale air is drawn from warmer regions of the building, particularly warm regions where that heat is of limited utility to building occupants -for instance above head height, at the top of a stair well or in a building plantroom. This may maximise the efficiency of heat transfer to fresh air drawn into the MVHR unit. However, where high humidity levels or high indoor pollution levels are detected or predicted in other regions of the building, for instance in bathrooms and kitchens, then stale air may be drawn preferentially from those locations. This may remove the need for dedicated extraction systems for those locations in addition to an MVHR building ventilation system.
[0007] The MVHR unit may further comprise a controller configured in use to receive a control signal or a sensor signal and in response control the stale air valve such that in use the stale air inlet receives stale air from the first stale air supply duct or the second stale air supply duct.
[0008] According to a second aspect of the present invention there is provided a building ventilation system comprising: an MVHR unit as described above; and a sensor configured to detect an environmental parameter or an indication of a potential change in the environmental parameter and transmit to the controller a control signal or sensor signal indicative of the environmental parameter.
[0009] According to a third aspect of the present invention there is provided a stale air valve mechanism comprising: a stale air valve connecting first and second stale air supply ducts and a stale air outlet duct; and a controller configured in use to receive a control signal or sensor signal and in response control the stale air valve such that in use the stale air inlet duct selectively receives stale air from the first stale air supply duct or the second stale air supply duct.
[0010] An advantage of the third aspect of the invention is that the stale air valve mechanism may be coupled to a conventional MVHR unit, either during initial commissioning or as a later, retrofit solution. The MVHR unit may be conventionally controlled, and the stale air valve mechanism independently controlled to source stale air appropriately.
[0011] According to a fourth aspect of the present invention there is provided a building ventilation system comprising: an MVHR unit comprising: a fresh air inlet to receive fresh air and a fresh air outlet to discharge fresh air, the fresh air outlet being coupled to the fresh air inlet through a fresh air duct; a stale air inlet to receive stale air and a stale air outlet to discharge stale air, the stale air outlet being coupled to the stale air inlet through a stale air duct; and a heat exchanger configured so that heat can be transferred between stale air in the stale air duct and fresh air in the fresh air duct; a stale air valve mechanism according to claim 4 coupled to the MVHR unit stale air inlet so that in use the MVHR unit stale air inlet receives stale air from the first or second stale air supply ducts via the stale air valve; and a sensor configured to detect an environmental parameter or an indication of a potential change in the environmental parameter and transmit to the controller a control signal or sensor signal indicative of the environmental parameter.
[0012] The environmental parameter may comprise temperature, humidity, or a measure of indoor pollution. The sensor may comprise at least one of: a humidity sensor; a particulate matter sensor; a gas sensor; a motion sensor; or a sensor providing a signal indicative of whether a light or appliance has been turned on in the second location.
[0013] At least one of the fresh air duct and the stale air duct in the MVHR unit may include a bypass channel which selectively allows the heat exchanger to be bypassed.
[0014] The stale air valve may be controllable to receive stale air: solely from the first stale air supply duct; solely from the second first stale air supply duct; or in variable proportion from both stale air supply ducts.
[0015] The building ventilation system may further comprise stale air supply ducting including the first and second stale air supply ducts coupled to the stale air valve.
[0016] According to a fifth aspect of the present invention there is provided a building comprising: a building ventilation system as described above; wherein the first and second stale air supply ducts extend from the stale air valve to respective first and second locations within the building.
[0017] The first location within the building may comprise a location in which the ambient temperature is generally higher than the average ambient building temperature, for instance one or more of: an upper portion of a stair well; an upper floor of the building; a building plant room; or a location proximal to a heat exchange radiator of a domestic appliance or a cooling system.
[0018] The second location within the building may comprise a location in which the humidity or indoor pollution is intermittently higher than the average building humidity or indoor pollution or where indoor pollution is intermittently higher than the building average, for instance one or more of: a bathroom; a toilet; a kitchen; a cooker hood within a kitchen; or a gym.
[0019] The building may further comprise: a fresh air exterior inlet on an exterior portion of the building, the fresh air exterior inlet being coupled to the MVHR unit fresh air inlet through fresh air supply ducting; a stale air exterior outlet on an exterior portion of the building, the stale air exterior outlet being coupled to the MVHR unit stale air outlet through stale air exhaust ducting; and at least one fresh air room outlet coupled to the MVHR unit fresh air outlet through fresh air exhaust ducting.
[0020] According to a sixth aspect of the present invention there is provided a method of operating an MVHR unit, the MVHR unit comprising: a fresh air inlet to receive fresh air and a fresh air outlet to discharge fresh air, the fresh air outlet being coupled to the fresh air inlet through a fresh air duct; a stale air inlet to receive stale air and a stale air outlet to discharge stale air, the stale air outlet being coupled to the stale air inlet through a stale air duct; and a heat exchanger configured so that heat can be transferred between stale air in the stale air duct and fresh air in the fresh air duct; wherein the stale air inlet includes a stale air valve; and wherein the method comprises controlling the stale air valve to selectively receive stale air from first and second stale air supply ducts.
[0021] According to a seventh aspect of the present invention there is provided a method of operating a stale air valve mechanism, the stale air valve mechanism comprising: a stale air valve connecting first and second stale air supply ducts and a stale air outlet duct; and a controller; wherein the method comprises: receiving at the controller a control signal or sensor signal; and in response to receiving the control signal or sensor signal, the controller controlling the stale air valve such that the stale air outlet duct selectively receives stale air from the first stale air supply duct or the second stale air supply duct.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Examples of the invention are further described hereinafter with reference to the accompanying drawings, in which: Figure 1 schematically illustrates an MVHR unit in accordance with an embodiment of the present invention; Figure 2 schematically illustrates an MVHR system including an MVHR unit and a stale air valve mechanism in accordance with an embodiment of the present invention; Figure 3 schematically illustrates pads of an MVHR system within a building according to an embodiment of the present invention; and Figure 4 is a flow chart illustrating a method of operating an MVHR unit or a stale air valve mechanism according to an embodiment of the present invention.
DETAILED DESCRIPTION
[0023] The present invention relates to a building ventilation system. In particular, the present invention relates to a building MVHR system. In some embodiments the present invention comprises a modification to an MVHR unit such that the MVHR unit is able to selectively receive stale air from different supply ducts and hence from different regions of a building according to where it is most advantageous to source the stale air. In other embodiments a stale air valve mechanism is provided separate from an MVHR unit (which may be wholly conventional) upstream of the MVHR unit stale air inlet. The stale air valve mechanism is able to selectively receive stale air from different supply ducts and hence from different regions of a building. In a normal operation mode, it may be that stale air is drawn from warmer regions of the building. However, where high humidity levels or high indoor pollution levels are detected or predicted in other regions of the building, then stale air may be drawn preferentially from those locations.
[0024] The term building" should be broadly construed to mean any structure defining a space which is wholly or partially contained. The term "building" includes industrial, commercial, retail and office buildings or structures as well as domestic premises including houses and apartments (hereinafter referred to as "homes"). The present invention is not limited to the use of an MVHR unit in any particular type of building. However, as will become apparent from the following description, embodiments of the present invention are particularly suited to the use of an MVHR system within a home. This is because the nature of a home relative to other types of buildings is that there may be a wider range of temperature, indoor pollution, and humidity within the building, for instance due to the presence of kitchens and bathrooms. Accordingly, a ventilation system able to more efficiently respond to the different environmental parameters within a home may be particularly desirable.
[0025] In some embodiments of the present invention an MVHR unit is specified to provide a total fresh air flow within the typical ranges experienced for a domestic building. This may be within the range 10 m3/h to 1000 m3/h, optionally over 100 m3/h and optionally less than 500 m3/h. The flow of fresh air and the flow of stale air through an MVHR unit is typically driven by one or more fans or other forms of pumps in the respective air flow paths. In accordance with the present invention the flow of stale air may be the same as the flow of fresh air so that the ventilation system is balanced and has a neutral effect on the pressure within the building. However, certain embodiments of the present invention may permit a mode of operation that is slightly unbalanced, for instance with a slightly higher volume of fresh air being delivered to the building relative to the extracted volume of stale air. This may have the effect of slightly pressurising the building relative to the exterior environment. In some situations, this may be desirable in order to ensure that the house is ventilated with fresh air and any excess escapes through building leakage or intended ventilation apertures, for instance a window trickle vent.
Advantageously, this prevents uncontrolled air from entering the building. Especially in the case that the fresh air through an MVHR unit is filtered and dehumidified, this can assist in reducing damp and pollution within the building. It is noted that in the following description conventional features of MVHR units such as fans, vents, additional heaters, and dehumidifiers (or humidifiers if required) are not explicitly described but may be included within embodiments of the present invention.
[0026] Referring first to figure 1, this schematically illustrates an MVHR unit 101 according to an embodiment of the present invention. Parts of the MVHR unit 101 may be conventional except as specifically noted below. The MVHR unit 101 comprises a housing 102 that contains the working parts. A fresh air inlet 103 is configured to receive fresh air and a fresh air outlet 104 is configured to discharge fresh air. The fresh air outlet 104 is coupled to the fresh air inlet 103 through a fresh air duct 105. A stale air inlet 106 is configured to receive stale air and a stale air outlet 107 is configured to discharge stale air. The stale air outlet 107 is coupled to the stale air inlet 106 through a stale air duct 108. The passage of stale and fresh air in and out of the MVHR is indicated by the arrows at the inlets and outlets. A heat exchanger 109 is configured so that heat can be transferred between stale air in the stale air duct 108 and fresh air in the fresh air duct 105. In some examples of the present invention (also in respect of figure 2, described below) one or both of the stale air duct and fresh air duct may include a bypass channel bypassing the heat exchanger so that the MVHR unit can be controlled to prevent the exchange of heat between air flows. For instance, this may be selectively activated during summer months in which the air inside the house is warmer than required, and so it is desirable to exhaust heat to outside of the building without transferring that heat to incoming fresh air. This may especially be the case if the air inside the building is warmer than the air outside of the building. Similarly, during winter months if the air inside the building is colder than the air outside of the building then the bypass may be activated to prevent heat being transferred from incoming fresh air to exhaust stale air.
[0027] According to an embodiment of the present invention, and differing from a conventional MVHR unit, the stale air inlet 106 includes a stale air valve 110 configured in use to selectively receive stale air from first and second stale air supply ducts 111, 112. The stale air valve 110 is controlled by a controller 113. The controller 113 may control the stale air valve 110 to selectively receive stale air from the first stale air supply duct 111 or the second stale air supply duct 112 or from a mixture of both ducts 111, 112 in variable proportion. This control may be responsive to the receipt of a control signal, for instance a sensor signal, by the controller 113, as is described later in this specification.
[0028] In essence, the fresh air flow path for the MVHR unit 101 is conventional, and the stale air path is conventional from the heat exchanger 109 onwards. However, according to the present invention, upstream of the heat exchanger 109 the stale air valve permits stale air to be drawn from different locations within a building. As is described in greater detail below, for an MVHR unit 101 installed within a home, a first, default, location may be a hot portion of the home, for instance the top of a stairwell where the hot air is redundant. This provides maximum heating to incoming fresh air (where the ambient environment outside of the home is cooler than that within the home). A second location is a potentially humid location, for instance a kitchen or bathroom to extract humid air when required. This may remove the need for a separate humid air extraction system for those rooms. A second location may also or alternatively be a location where indoor air pollution is typically higher, for instance a room with a gas-powered appliance or cooking facilities. It will be appreciated that the present invention is extensible to the stale air valve selectively receiving stale air from any number of different locations within a building, including through selection between more than two stale air supply ducts. Furthermore, the stale air valve may selectively mix the stale air flows though different ducts, for instance if there is an insufficient flow from a humid location. That is, the valve need not be limited to being fully on or fully off in respect of each supply duct. This may permit the mix of stale air drawn into the MVHR unit to be optimised for heat recovery and moisture/indoor pollution control (through the use of suitable further sensing as required, as well as or in place of humidity sensing or indoor pollution sensing). Different modes of operation of the MVHR unit 101 are set out in the following description.
[0029] Tuning now to figure 2, this schematically illustrates a stale air valve mechanism 220 according to an embodiment of the present invention in combination with an MVHR unit 201. The MVHR unit 201 may be wholly conventional, the stale air valve mechanism 220 serving to selectively receive stale air from a first stale air supply duct or second stale air supply duct upstream of the MVHR unit. The MVHR unit 201 thus differs from the MVHR unit 101 of figure 1 in respect of the stale air inlet 206. The remaining features may be identical and so features that correspond to those previously described for figure 1 are given the same reference numbers incremented by 100.
[0030] In the MVHR unit 201 of figure 2 the stale air inlet 206 comprises a simple inlet mechanism. The stale air valve mechanism 220 comprises a stale air valve 221 selectively connecting first and second stale air supply ducts 222, 223 and a stale air outlet duct 224 that is coupled to the MVHR unit stale air inlet 206 through appropriate stale air supply ducting 225. Although displayed proximal to the MVHR unit 201, no particular spatial relationship for the stale air valve mechanism 220 should be inferred: it may suitably be located at any upstream location anywhere within stale air supply ducting forming part of a complete building ventilation system.
[0031] The stale air valve mechanism 220 further includes a controller 226 configured in use to receive a control signal, for instance a sensor signal, and in response control the stale air valve 221. Functionally, controller 226 and stale air valve 221 operate in the same way previously described for controller 113 and stale air valve 110 of figure 1, differing only in their location outside of the MVHR unit instead of forming part of the MVHR unit, and so the description of this functionality is not repeated. This separation advantageously removes any requirement to modify a conventional MVHR unit.
[0032] Turning now to figure 3, this schematically illustrates parts of an MVHR system within a building. The building is schematically represented by a ground floor floorplan 301 and a first-floor floorplan 302. The number of floors and the distribution of rooms on each floor should not be considered to be limiting. Figure 3 illustrates an MVHR unit 101 according to figure 1, though equally this may be the MVHR unit 201 of figure 2 in combination with the stale air valve mechanism 220 of figure 2. The MVHR unit 101 is shown in figure 3 to be spaced apart from the ground floor 301 and first-floor 302. It will of course be understood that it will be physically located in one of the rooms within the building.
[0033] Figure 3 illustrates first and second stale air supply ducts 111, 112, though equally this could be the first and second stale air supply ducts 222, 223 of figure 2. The first and second stale air supply ducts 111, 112 are shown extending from the MVHR unit 101 (specifically, the stale air valve 110) to respective first and second locations within the home. In fact, each stale air supply duct 111, 112 is shown branched and extending to two or more rooms within the home, and hence two or more respective first and second locations, though this is not to be construed as limiting on the claimed scope of protection.
[0034] Each first location within the building comprises a location in which the ambient temperature is generally higher than the average ambient building temperature. For instance, a first location may comprise one or more of an upper portion of a stair well, an upper floor of the building, a building plant room, or a location proximal to a heat exchange radiator of a domestic appliance or a cooling system. In the example of figure 3, first stale air supply duct 111 is shown extending to stale air room inlets 303 in a plant room 304 on the ground floor 301 and a top of a stairwell 305 on the first-floor 302. Nothing should be construed about the exact location of a stale air room inlet 303 in any room of the building from the illustrated position in figure 3.
[0035] Each second location within the building comprises a location in which the humidity is intermittently higher than the average building humidity or where indoor pollution, for instance the measured amount of particulate matter or a gas for instance CO2, is intermittently higher than the building average. For instance, a second location may comprise one or more of a bathroom, a toilet, a kitchen, a cooker hood within a kitchen, or a gym. In the example of figure 3, second stale air supply duct 112 is shown extending to stale air room inlets 303 in a toilet 306 on the ground floor 301, a kitchen 307 on the ground floor 301, and a bathroom 308 on the first-floor 302.
[0036] Figure 3 further illustrates a sensor 309 within each second location (that is, the toilet 306, kitchen 307 and bathroom 308). Each sensor 309 is configured to transmit a control signal to the controller indicative of a current or predicted increase in humidity or indoor pollution in the second location. It is not necessarily the case that each sensor 309 is of the same sort or measures the same parameter. Furthermore, while figure 3 illustrates the sensor 309 being coupled via a wired network 310 to the MVHR unit 101 (particularly the controller 113), this should not be construed as limiting: for instance, a wireless connection may be used.
[0037] In response to the control signal or sensor signal, controller 101 of figure 1 (or controller 226 of figure 2) is configured to determine whether to control the stale air valve 110 (or the stale air valve 221 of figure 2) to receive stale air from the second location 306, 307, 308 via the second stale air supply duct 112 as well as or in place of receiving stale air from the first location 304, 305 via the first stale air supply duct 111. In further examples of the present invention, there may be one or further valves such that individual locations may be selected: for instance, only the stairwell 305 or only the bathroom 308.
[0038] A sensor 309 may indicate a current high humidity or high pollution event, or where one is predicted. Current signals may be provided directly through a humidity sensor or a pollution sensor, such as particulate matter sensor or gas sensor. A predicted event may be predicted for instance by using a motion sensor to detect a person entering a room such as a bathroom, where it is likely that high humidity will shortly be experienced. Similarly, the sensor may simply detect that a light has been switched on in a second location (either directly, by being wired into the lighting circuit or via a light detector.
Sensors 309 in some cases may be incorporated into the stale air room inlet 303. Other sensor types may detect when a device that typically generates high humidity or pollution is activated, for instance an oven or hob or a shower. The controller 101 may be configured to continue to extract stale air for a period of time after a signal indicating a current or predicted high humidity or air pollution event has ended. This may be a predetermined period, for instance to continue to exhaust stale air from a toilet or bathroom for a predetermined period of time after a light has been switched off.
[0039] It will be appreciated that the present invention is extensible to an MVHR system in which all or a majority of rooms include a stale air room inlet and one or more sensor types allowing air quality to be measured or predicted in all or a majority of rooms and the stale air supply to the MVHR unit selected to optimise air quality throughout the building.
[0040] In some situations, sensors may be incorporated into the stale air room inlets in order to provide for a simplified method of installation that does not require further steps for the installer. The MVHR unit or stale air valve mechanism may be provided as a ventilation system kit in combination with the sensors. The sensors may be battery powered or coupled to a mains electricity supply. The sensors may communicate directly with the stale air valve controller without the need for integration with any form of wider building control system. The communication with the controller may be wireless. In some cases, it may be wired. In some cases, a wired connection and optionally a power supply may be incorporated into the ventilation system ducting, again to avoid the need for any additional installation steps.
[0041] In the absence of a control signal to the controller indicative of a current or predicted increase in humidity or indoor pollution in a second location, the controller may be configured to control the stale air valve to receive stale air from the first location or to receive a majority of stale air from the first location.
[0042] Although not illustrated in figure 3, it will be appreciated that the building (particularly, the building ventilation system) will further comprise a fresh air exterior inlet on an exterior portion of the building, the fresh air exterior inlet being coupled to the MVHR unit fresh air inlet through fresh air supply ducting, a stale air exterior outlet on an exterior portion of the building, the stale air exterior outlet being coupled to the MVHR unit stale air outlet through stale air exhaust ducting, and at least one fresh air room outlet coupled to the MVHR unit fresh air outlet through fresh air exhaust ducting.
[0043] The sensors described above are intended for one specific example of the present invention in which normally stale air is sourced from a first location which is a warm location and in response to a sensor signal or control signal the stale air valve is actuated to receive stale air from a humid location. However, the present invention is not limited to this. More generally, any form of sensor including temperature, humidity and pollution sensors may be used to provide the controller with information concerning the indoor environment (or a predicted change in the indoor environment) at one or more location where stale air may be extracted. The controller may then select which location (or which combination of locations) within the building from which to supply stale air to the MVHR unit. For instance, in other examples, the stale air may be sourced from the most overheated location within the building, or from the most humid or polluted locations. In some examples, the stale air may by default be extracted from typically humid locations I5 and warm locations only vented on demand. Numerous further configurations and modes of operation using commercially available sensor types and combinations of valves will be appropriate to the skilled person. At its broadest, the present invention is concerned with providing the controller with the information to determine the optimum location from which to draw stale air to maintain a desired environment within the building.
[0044] Turning now to figure 4, this is a flow chart illustrating a method of operating an MVHR unit or a stale air valve mechanism according to an embodiment of the present invention. At step 401, the controller may initially control the stale air valve to receive stale air from a first location. As noted above the first location is one in which the obtainable stale air temperature is higher than average. At step 402 the controller receives a control signal or sensor data indicating that a high humidity or indoor pollution event is current or predicted in a second location. In response, at step 403 the controller actuates the stale air valve to change the stale air supply ducts that are coupled to the MVHR unit. At step 404 the stale air valve receives stale air from the second location in place of or partially in addition to receiving stale air from the first location. As noted previously, the valve may be controlled to receive stale air in any proportion between the or each first and second locations. Where there is multiple first and second locations and appropriate ducting and control valves, the controller may be configured to selectively receive stale air from any specific location.
[0045] Throughout this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other components, integers, or steps. Throughout this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. Throughout this specification, the term "about" is used to provide flexibility to a range endpoint by providing that a given value may be "a little above" or "a little below" the endpoint. The degree of flexibility of this term can be dictated by the particular variable and can be determined based on experience and the associated description herein.
[0046] Features, integers, or characteristics described in conjunction with a particular aspect or example of the invention are to be understood to be applicable to any other aspect or example described herein unless incompatible therewith. All of the features disclosed in this specification, and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing examples. The invention extends to any novel feature or IS combination of features disclosed in this specification. It will also be appreciated that, throughout this specification, language in the general form of "X for Y" (where Y is some action, activity or step and X is some means for carrying out that action, activity, or step) encompasses means X adapted or arranged specifically, but not exclusively, to do Y. [0047] Each feature disclosed in this specification may be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
[0048] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.