Patent Description:
Fan coil units are one of the most popular types of air conditioning unit in the world, and can be found in residential, commercial, and industrial buildings. A fan coil unit is essentially a device comprising a heating or cooling coil and fan. Due to their simplicity, fan coil units are often more economical to install than ducted cooling and heating systems with air handling units. However, they can be noisy because the fan is within the temperature controlled space. Furthermore, if the fan coil unit or an 'all air' system is installed within a suspended ceiling, it can require large floor to floor heights to provide the space to accommodate the fan coil unit. They can also complicate maintenance as the suspended ceiling must be removed to access the unit.

A cassette air conditioning unit is a form of fan coil unit in which ceiling mounted cassettes are mounted in a ceiling void so that only a fascia is visible. The internal unit incorporates a cooling or heating coil and directional flaps allow air to be distributed around a room in <NUM>, <NUM>, or <NUM> different directions.

Prior art arrangements are known from <CIT>, <CIT> and <CIT>. <CIT> discloses an air conditioning unit having a main body, a fan, a thermal element, wherein the thermal element is disposed within the airflow passage upstream of the fan and the air inlet and the thermal element are arranged at the periphery of a first face on which the outlet is disposed.

According to the present invention, there is proposed an air conditioning unit as defined in claim <NUM>.

The air conditioning unit provides for an airflow velocity at the thermal element that is lower, for a given total airflow through the fan, than the airflow velocity at the thermal element in prior art arrangements where the air inlet and thermal element are central on the face of the unit/central within the body of the unit. A greater surface area is available at the periphery of the first face than at a more central location.

Preferably the air inlet and thermal element extend along at least <NUM>% of the periphery of the first face, and more preferably at least <NUM>% of the periphery of the first face. In preferred embodiments, the periphery of the first face may also include space for connections to building utilities such as electrical power and/or incoming/outgoing working fluid for the thermal element. It is preferred for the thermal element and air inlet to extend around the entirety of the available space about the periphery of the first face, which in the case above would be the space not required for connection to building utilities.

Preferably the air inlet, the air outlet and the airflow passage are arranged such that, in use, the airflow velocity through the airflow passage at the thermal element is less than <NUM>%, preferably less than <NUM>%, of the airflow velocity through the airflow passage downstream of the fan, e.g. at an output of the fan. Where there is relatively little pressure increase caused by the fan, this is approximately equivalent to the airflow passage cross-sectional area at the thermal element being at least twice, preferably at least three times, that of the airflow passage cross-sectional area at the output of the fan.

In a preferred embodiment, the air conditioning unit may be arranged such that, when the fan is driven to give an air output velocity of about <NUM> metres/second at the first face, the airflow velocity through the airflow passage at the thermal element is between <NUM> and <NUM> metres/second, and preferably about <NUM> to <NUM> metres/second. This is much lower than in most fan coil units, which operate at an air velocity of around <NUM> metres/second at the cooling coils.

This configuration, which takes advantage of the reduced airflow velocity at the thermal element discussed above, both reduces the pressure drop across the thermal elements and increases the thermal transfer rate between the thermal elements and the airflow. Hence, the heat transfer efficiency can be increased, whilst also reducing the work required to be performed by the fan.

The main body may comprise one or more second faces extending from the periphery of the first face, and the air inlet may be disposed on the second face(s).

The one or more second faces are preferably generally perpendicular (e.g. within about <NUM>° of perpendicular) to the first face. The second face(s) hence may essentially be side faces of the unit, with the first face being a front face. Any number of side faces may be provided, for example where the main body is rectangular there will be four side faces. Other shapes may also be used, for example an air conditioning unit having a triangular shape would have three side faces.

In preferred embodiments, the first face of the air conditioning unit is rectangular, preferably having a width of less than <NUM> and a length of less than <NUM>. The main body of the air conditioning unit is preferably generally cuboid. This enables the main body to be conveniently installed in a standard ceiling grid. With a generally cuboid shape the second faces would be sides of the cuboid, extending away from the sides of the rectangular first face and being generally perpendicular to the surface of the first face.

Preferably the main body of the air conditioning unit has a thickness of less than <NUM>, more preferably less than <NUM> and most preferably <NUM> or less. Conventional fan coil units have not been able to achieve such thicknesses. However, the arrangement of the present invention allows these low thicknesses to be achieved.

In some embodiments, the thermal element may comprise a thermal coil for heat exchange with air flowing across the coil, such as a water-cooled coil. This may be arranged either in a cooling only ('<NUM>-pipe') coil configuration or a cooling and heating ('<NUM>-pipe') coil configuration. The thermal element may further comprise heat exchange fins adjacent to the air inlet, so as to maximise heat transfer between the coil and the air.

In alternative embodiments, the thermal element may instead be a chilled beam for heat exchange with air flowing through the chilled beam.

According to the present invention, the fan is oriented such that a rotational axis of the fan is substantially perpendicular to the first face, such that a relatively large diameter fan can be used without increasing the thickness of the main body of the unit (i.e. the distance from the front face to the rear of the main body). In some embodiments, the diameter of the fan may be greater than <NUM>. It will be noted that the preferred placement of the fan on the first face and at a centre of the unit allows for maximum space for a large diameter of fan, without restricting the space available for the air inlet and thermal elements, which are at the periphery around the fan.

The fan vents air directly into the temperature-controlled space. This is contrary to the arrangement of most traditional fan coil units, where the fan vents the air through further downstream components, such as diffuser fins, secondary ducting, and so on.

According to the present invention, the fan is configured to provide a swirl effect to the air output into the temperature-controlled space. That is to say, the air discharges straight from the tips of the fan blades in a pattern that spreads out in a circular flow. Although a similar effect can be achieved in conventional units using a swirl diffuser, this causes energy loss as the airflow is redirected by blades. The swirl effect causes a high induction air flow, which is desirable because it can introduce cold air into a conditioned space with less risk of draughts. Using the fan to provide the swirl effect rather than by blades minimises changes in direction for the air, and minimises energy loss.

The impellors of the fan may include a ramp at their tips, just before the discharge, to increase the downward velocity of the air. This can help to achieve the preferred high induction air pattern. In some embodiments, turning vanes may be included in the airflow passage upstream of the fan to smooth the airstream, reduce friction and reduce the pressure drop at the bend between the air inlet and the fan.

The air conditioning unit, as detailed in any of the above statements, may be arranged to be mounted vertically, i.e. with the first face extending substantially vertically. In such a configuration, if the periphery of the first face includes space for connections to building utilities such as electrical power and/or incoming/outgoing working fluid for the thermal element, this space will be provided on an upper substantially horizontally extending peripheral side of the first face. The thermal element and air inlet will extend around substantially the entirety of the available space about the periphery of the first face, which in this case would be the space not required for connection to building utilities, i.e. the space about the lower substantially horizontally extending peripheral side and about the substantially vertically extending peripheral sides of the first face. In such an arrangement, the portion of the thermal element extending along lower substantially horizontally extending peripheral side of the first face may be provided at an oblique angle to the vertical/front face, preferably at an angle of around <NUM> degrees.

Further according to the present invention, the thermal element is mounted to a first housing portion of the main body and the fan is mounted to a second housing portion of the main body, the second housing portion being hinged with respect to the first housing. As a result, the second housing portion is rotatable via the hinge with respect to the first housing portion from a first position to a second position, wherein the fan is operable for normal use in the first position and is accessible for maintenance in the second position. Preferably the second housing portion includes the first face and is adapted so as to be exposed, in use, to the temperature controlled space.

Thus, the air conditioning unit allows 'self-access'. That is to say, components of the air conditioning unit requiring access (e.g. for maintenance), such as the fan and filters, can be reached simply by unlatching and rotating the second housing, rather than for example requiring removal of ceiling tiles and disassembly or removal of the fan coil unit, as is presently required. As the rotatable second housing portion remains attached to the rest of the unit, which is attached to the ceiling or other support, then maintenance can be carried out in situ without the need to disconnect the power supply or heat/cooling source.

The air conditioning unit may include an air filter in the airflow passage upstream of the fan, and preferably also upstream of the thermal element.

The filter is preferably arranged within the main body such that it cannot be removed from the main body when the second housing portion in the first position and can be removed from the main body when the second housing portion is in the second position. In some arrangements, the filter may be releasably mounted within the first housing portion.

The air conditioning unit preferably further comprises a drip tray arranged so as to be, in use, vertically below at least the thermal element. Where multiple thermal elements are provided, the drip tray will overlap with all of the vertical elements. The drip tray is thus configured to catch condensate that forms on the thermal element when operating in a cooling mode. When any of the thermal elements is provided at an oblique angle to the vertical, as for example when the air conditioning unit is arranged to be mounted vertically, the drip tray may only partially overlap with the angled thermal element to leave a free space for the flow of outside air to the angled thermal element through a lower horizontally extending second face. Condensate will run down the angled face to collect in the drip tray. The drip tray (or one or more additional drip trays) may also be provided under further chilled components of the air conditioning unit, such as cooling medium valves and pipes connecting to the thermal element.

The or each drip tray preferably contains a hydrophilic member, such as a tube formed of hydrophilic material, which is disposed within the drip tray to collect condensate caught by the drip tray. The use of a hydrophilic material allows water to be drawn into the material, avoiding the need for gravity drainage, which would increase the thickness of the air conditioning unit. Instead, the condensate can be drawn via the member along a drip tray that is substantially horizontal along its length, or even up a slight incline in situations where the air conditioning unit is not installed perfectly level.

The drip tray may have a sloped floor arranged to, in use, direct the condensate toward the hydrophilic member. This allows a smaller hydrophilic member to be used without significantly increasing the thickness of the unit. Preferably the drip tray is elongate and the slope is perpendicular to the longitudinal direction of the tray, i.e. so as to direct the condensate toward an elongate hydrophilic member running substantially the length of the drip tray. Preferably the drip tray is arranged so as to be substantially horizontal, in its longitudinal direction in use. As the air conditioning unit is preferably very thin, a steep gradient cannot be provided across the entire length of the drip tray to drain condensate to a single drainage location. Instead, a local gradient directs the condensate to the hydrophilic member, which collects the condensate.

The air conditioning unit may further comprise a pump arranged to draw the condensate along the hydrophilic member. In some embodiments, a moisture detector, such as moisture detection tape, may be provided adjacent to the hydrophilic member, and the pump may then be arranged to activate when moisture is detected by the moisture detector. Thus, when the hydrophilic member is saturated with condensate, the unabsorbed moisture will be detected and the pump will activate, e.g. for a predetermined period of time, to drain the moisture absorbed by the hydrophilic member. This then minimises the time the pump is active, reducing the energy required for the pump and any pump noise. The pump will be arranged to have minimal noise when running.

The air conditioning unit preferably further comprises: an installation frame adapted to be mounted to the ceiling during a first fix and comprising isolatable connections for services of the air conditioning unit to be connected, wherein the main body is adapted to be mounted to the installation frame during a second fix.

By this arrangement, the installation frame can be installed during the first fix and the services, such as power lines, control lines and/or cooling/heating medium pipework, can be connected to the isolatable connections. Then, at a later time during a second fix, the main body of the air conditioning unit can be installed. This means that workflow can be optimised as the various services need merely be connected to the installation frame when they are installed in the ceiling. This is more efficient than fitting them all at the same time as the air conditioning unit is installed, as it gives flexibility for different trades to attend to make connections at different times.

In an example, not covered by the present invention, a method of installing the air conditioning unit comprises: fixing the installation frame to a ceiling; installing ceiling services, terminating at the isolatable connections of the installation frame; installing a suspended ceiling; and mounting the main body of the air conditioning unit onto the installation frame.

In some embodiments, the air outlet may be adapted to receive a light emitting device. That is to say, it may include for example light fittings for lamps to be inserted. The output air is then output around the light allowing the air conditioning unit to provide a dual function. The air outlet may further be arranged to act as a light diffuser for the light emitting device.

In some embodiments, the air conditioning unit may be adapted to be suspended from a ceiling, for example as a pendant. This may be appropriate for retail use, or restaurants, with exposed ceilings. There is also a move in office design towards removing suspended ceilings and having exposed services and suspended units. In such an embodiment, the main body may include second faces that are hinged to permit access.

Where the air conditioning unit is adapted to be suspended, the unit may further comprise a rim member surrounding the main body. Preferably rim member has an outer edge having a height less than <NUM>% of the thickness of the main body. The rear of the rim member will be hard to see from below, this giving the illusion of a slim unit.

The rim member may include additional services, such as lights, fire detectors, sprinklers, public announcement facilities, and so on, thus allowing the air conditioning unit to act as a multiservice unit.

An embodiment of invention can also be seen to provide a structure including the air conditioning unit, wherein the structure comprises a floor, a ceiling and a temperature controlled space defined between the floor and the ceiling, and wherein the main body of the air conditioning unit is disposed within a ceiling void of the ceiling such that the first face is exposed to the temperature controlled space.

In some embodiments, the structure is arranged such that air is drawn into the temperature controlled space via a floor void of the floor.

An alternative embodiment of the invention can be seen to provide a structure including the air conditioning unit, wherein the structure comprises a floor, a ceiling, a vertical wall and a temperature controlled space defined between the floor, the ceiling and the wall, and wherein the main body of the air conditioning unit is disposed within the vertical wall such that the first face is vertical and exposed to the temperature controlled space. The vertical wall may include a void adjacent the air inlet of the air conditioning unit, the cavity being in gaseous communication with the temperature controlled space.

In this arrangement, the vertically-mounted air conditioning unit can be installed into a wall. The low profile of the air conditioning unit enables it is be installed in the wall without unduly limiting the space within the room. This configuration may be particularly well suited to a small computer room, such as an SER (Small equipment Room) or SCR (Sub Comms Room).

The use of a hydrophilic member allows condensate to be drawn into the material providing the advantages discussed above.

The drip tray may have a sloped floor as described above to, in use, direct the condensate toward the hydrophilic member.

The condensate removal system according to an example not falling under the present invention, may advantageously be combined with an air conditioning system of the type described above, but it also provides advantages with other air conditioning systems. This is because the depth/height required to house a condensate removal system is reduced by the system of this aspect. Thus, any air conditioning unit can be redesigned to have a lower profile, and a condensate removal system can be included even when space is limited. It can be a significant advantage to allow for an air conditioning unit to have a 'wet' mode, since it increases the range of temperature and humidity within which the unit can operate. In addition, the condensate removal system can be more effective at gathering condensate due to the use of hydrophilic materials. This reduces the risk of drips, leakage or flooding.

Certain preferred embodiments of the present invention will now be discussed in greater detail, by way of example only and with reference to the accompanying drawings, in which:.

<FIG> shows a cross section through an exemplary building illustrating airflow through an air conditioning unit <NUM>. It should be noted that whilst the detailed description herein focusses on the use of such air conditioning units in buildings, they may equally be suitable for transport applications, such as coaches and railway carriages, or otherwise, due to their low height. The building uses a floor plenum <NUM> to provide an outside air supply and a ceiling plenum <NUM> for air extraction. Outside air enters a temperature controlled space <NUM> from the floor plenum <NUM> via floor outlets <NUM> formed in a raised floor <NUM>. Air is circulated within the space <NUM> and is eventually extracted through a suspended ceiling <NUM> into the ceiling plenum <NUM> via ceiling openings <NUM>, such as via the light fittings, as illustrated in <FIG>.

This arrangement may not suit some projects, for example where smoke extract ductwork is required, but is intended to illustrate one exemplary configuration. Depths of <NUM> are suitable for each of the supply and extract plenums <NUM>, <NUM>, based on an assumed travel distance of <NUM> to <NUM> metres from the air supply in a central core of the building to the perimeter of the plenum <NUM>, <NUM>.

The shallow depth of the ceiling void <NUM> will require careful co-ordination of pipework, cables and other services. As shown, services <NUM> for the air conditioning unit <NUM> are delivered to and from the air conditioning unit <NUM> within the ceiling void <NUM>. Such services <NUM> include cooling/heating liquid medium, e.g. chilled or heated water, power and control supplied to the air conditioning unit <NUM> and condensed water and return refrigerant from the air conditioning unit <NUM>.

The air conditioning unit <NUM> is designed so as to achieve the same comfort quality standards as conventional air conditioning systems, e.g. fan coil units, chilled beams, chilled ceilings, VAV boxes, etc., whilst being only <NUM> high. It could save typically <NUM> on each storey height of a building. For a building where the height is limited to <NUM> metres (approximately <NUM> stories at <NUM> floor to floor height), this would add one floor within the same overall building height.

Furthermore, the air conditioning unit <NUM> does not require an accessible ceiling and can instead fit in the narrow <NUM> ceiling void <NUM> discussed above. Also, compared with a conventional fan coil system there is no secondary ductwork, and potentially far less primary ductwork.

As will be discussed below, the ductwork and pipework for the air conditioning unit <NUM> can be installed as part of first fix, and then a main body <NUM> of the air conditioning unit <NUM> including the fan <NUM> and coils <NUM> can be installed during a second fix, before or after the suspended ceiling <NUM> is installed. Commissioning, maintenance, and even unit replacement can be carried out after the ceiling <NUM> is installed.

<FIG> shows a sectional plan view, of a main body <NUM> of the air conditioning unit <NUM> shown in <FIG>. <FIG> and <FIG> show cross-sectional views of the main body <NUM> taken along section lines A-A and B-B.

The air conditioning unit <NUM> is defined by a main body <NUM> having a front face, a rear face, and four side faces. The front and rear faces of the main body <NUM> are generally parallel to one another and the side faces are generally perpendicular to the front and rear faces. Suitable fixing means <NUM>, which may comprise threaded rods, are preferably provided for suitably installing the air conditioning unit <NUM>. When installed, the front face is exposed to the temperature controlled space <NUM>.

The front face is substantially square having dimensions of about <NUM> x <NUM>, which is sized to fit a standard ceiling grid (although other shapes and/or dimensions could of course be utilised). The unit has a height of about <NUM> between the front and rear faces.

The front face comprises a facia plate <NUM> having air outlets <NUM> through which conditioned air is directly injected into the temperature controlled space <NUM>, i.e. there is no secondary ductwork. The air outlets <NUM> may comprise perforations in the facia plate and, at the outlets <NUM>, the facia plate <NUM> is preferably at least <NUM>% perforated. The side faces comprise air inlets <NUM> through which air is drawn into the air conditioning unit <NUM>. The air inlets <NUM> are not usually visible during normal operation and so may simply comprise openings, but a filter <NUM> or the like may also be used to prevent large debris entering the unit <NUM>, if desired.

Between the air inlets <NUM> and the air outlets <NUM> there is an airflow passage through which the air flows and is conditioned. In this arrangement, the airflow passage is defined by a fan plate 27a separating the air flowing into the fan <NUM> from the air being output by the fan <NUM>.

Within the main body <NUM> is provided one or more thermal element <NUM> to heat and/or cool the air in the airflow passage and a fan <NUM> to drive the air. The thermal elements <NUM> are provided upstream of the fan <NUM>. Also within the main body <NUM> may be provided a plurality of air filters <NUM>. The air filters <NUM> are disposed upstream of the thermal element <NUM>. An air filter <NUM> and a thermal element <NUM> are provided adjacent to each air inlet <NUM>. The air filters <NUM> are preferably retained by respective air filter guides 30a at their upper and side edges. The air filters <NUM> are retained in position by a clip at their lower edge.

The air inlets <NUM> are provided on three of the four sides of the air conditioning unit <NUM>. It is desirable to maximise the air inlet area so as to minimise the airflow velocity over the thermal elements <NUM>. However, some space must be left for the services <NUM> to enter the unit. Thus, it is not possible for the inlets <NUM> to cover more than about three and a half of the sides (less than about <NUM>% of the periphery of the air conditioner unit <NUM>). However, the air conditioner unit <NUM> would of course still operate with a smaller number of inlets <NUM>, for example air inlets <NUM> could be provided on only two sides, i.e. along at least <NUM>% of the periphery of the air conditioner unit <NUM>.

A baffle plate 29a is provided on the fourth face of the air conditioner unit, which wraps round the fan control unit <NUM> and condensate pump <NUM>, and prevents air from being drawn in, which would bypass the thermal elements <NUM>.

By providing the air inlets <NUM> about the periphery of the air conditioner unit <NUM>, the inlet area can be maximised. In this air conditioning unit <NUM>, the air travelling across the thermal element <NUM> travels at approximately <NUM> to <NUM> metre/second, which is significantly lower than in conventional fan coil units, where there air speed at the thermal element <NUM> is about <NUM> metres/second. This improves heat transfer to or from thermal element <NUM> and reduces the pressure drop across the thermal element <NUM>, allowing a smaller fan <NUM> to be used and hence allowing the air conditioner unit <NUM> to be made thinner than traditional fan coil units where the air would be drawn in at the centre at relatively high speed.

During operation, air enters the air conditioner <NUM> substantially horizontally through the air inlets <NUM> into the airflow passage. The air continues substantially horizontally through one of the air filters <NUM> and across a region of the thermal element <NUM>. The air is then drawn vertically downwards into the fan <NUM> and ejected directly out of the air conditioning unit <NUM> via the air outlets <NUM> into the temperature controlled space <NUM>.

The air conditioning unit <NUM> may include turning vanes (not shown) on the approach to the fan <NUM> to smooth the airstream and reduce friction. The arrangement shown in <FIG> is equivalent to a <NUM> degree bend via a plenum. Installing turning vanes in this location may reduce the pressure drop for this bend to <NUM>% of the pressure drop for a plenum arrangement (i.e. without any turning vanes).

The fan <NUM> is a plug fan, which has the known characteristic of having lower pressure drops and noise than the tangential fans normally used in fan coil units. The fan is driven by a motor (not shown), which may be a DC motor to give good energy performance and variable speed capabilities.

The blades of the fan <NUM> are arranged so as to direct the air ejected from the outlets in a pattern that spreads out in a circular flow. The blades may include a ramp just before discharge to increase the downward velocity of the air to achieve the desired air pattern.

To illustrate the efficiency of this configuration, one exemplary and non-limiting specific example will now be described. Based on a selection of <NUM><NUM>/s at <NUM> Pa, <NUM>% fan efficiency and <NUM>% motor efficiency, the fan power consumption will be about <NUM> W. Serving a floor area of <NUM><NUM>, this is a fan energy consumption of <NUM> W/m<NUM>. This is much lower than the usual "rule of thumb" concept design stage allowance of <NUM> W/m<NUM> for fan coil unit fan energy.

In the UK Building Regulations Part L there is a requirement to achieve a minimum Specific Fan Power (SFP) calculated as power (watts) per unit flow rate of air (litre/second). For fan coil units and other terminal units the required SFP inferred from the Part L energy calculation is <NUM> or lower. Using the figures above the SFP is <NUM>. This is again far better than the requirement.

In an embodiment of the present invention, a mixed flow fan is used, i.e. having curved blades in the centre, changing to vertical blades at the perimeter. Such a fan may also satisfy the conditions of low noise and low energy consumption, whilst fitting into a narrow air conditioning unit <NUM>, e.g. having a height of <NUM>.

According to the present invention, the blades of the fan <NUM> are designed so that the air conditioning unit <NUM> will provide a swirling air flow pattern, similar to a swirl diffuser. Further according to the present invention, the air discharges straight from the tips of the fan blades in a pattern that spreads out in a circular flow. This means that for minimal change of direction, and therefore minimal energy loss, a high induction air flow can be achieved.

It is desirable to minimise vibration from the fan <NUM> within the air conditioning unit <NUM> to minimise noise. This can be achieved by using high quality, well balanced fan <NUM>, and by the use of anti-vibration mounts 27b at the points where the fan is supported. For example, the fan <NUM> is supported by the fan plate <NUM> and is connected via anti-vibration mounts 27b.

The front face of the air conditioning unit <NUM> comprises a perforated facia plate <NUM>, with at least <NUM>% opening at the outlets <NUM>. This is sufficient for the air to pass through without altering the air flow characteristics.

As the air flow pattern from the fan <NUM> does not depend on the coanda effect from the adjacent ceiling, the air conditioning unit <NUM> can be pendant mounted (as will be discussed below) and will have the same air flow pattern as the unit <NUM> mounted in the ceiling. This fan arrangement also means that the air flow can be reduced to almost zero without cold air dumping. Cold air dumping is the phenomenon whereby a current of cold air, typically flowing horizontally below a ceiling and adhering to the ceiling due to the coanda effect, becomes detached from the ceiling, thereby falling down into the occupied space (dumping) with a consequent risk of cold draughts.

The air conditioning unit further includes air inlets <NUM> defined around the sides of the main body <NUM>.

As discussed above, the thermal elements <NUM> are provided along three peripheral sides of the air conditioning unit <NUM>. In this air conditioning unit <NUM>, the thermal elements <NUM> comprise thermal coils 26b and heat exchange fins 26a for maximising thermal transfer. The coils 26b receive heated or chilled water via inlet pipe(s) 18a, which is then pumped through the coils 26a before being returned via the return pipe(s) 18b to be regenerated. The condensate pump <NUM> may be located below or adjacent to the changeover and control valves, 32a and 32b, and pumps condensed water into the condensate return pipework 18c".

<FIG> show schematically the thermal coil 26b and the corresponding HVAC infrastructure, respectively. The present air conditioning unit <NUM> uses a single coil 26b, having valves 32a, 32b to provide a changeover from the heating pipes 18a", 18b" to the cooling pipes 18a', 18b', as required. Whilst this adds complexity to the circuit, it reduces the energy loss when driving air through the coil 26b.

<FIG> shows a cooling arrangement where cool water is supplied via the cold inlet pipe 18a'. In order to maximise the heat transfer in the coil 26b, a counterflow heat exchanger arrangement is used. One exemplary and non-limiting specific example will now be described - the flow water at <NUM> enters the downstream set of pipework, passes horizontally through the coils, heating up to <NUM>, then returns via the upstream set of pipework, and returns to the cold return pipe 18b' at <NUM>. In the cooling mode (as illustrated in <FIG>), a counterflow heat exchange configuration means that the coldest water (from the inlet pipe 18a') is adjacent to the air leaving the cooling coil 26b (radially inner side), and the warmer water (to the return pipe 18b') is adjacent to the air entering the cooling coil 26b (radially outer side). This gives the most efficient use of the heat exchange process, and gives the lowest possible air conditioner output temperature.

In an alternative arrangement, the changeover valves 32a, 32b and the heating medium inlet and return pipes 18a", 18b" may be omitted such that the coil 26b provides a cooling-only coil <NUM>. In such an arrangement, separate heating units may be provided at the perimeter of the building for heating when necessary.

In a further alternative arrangement, a separate heating coil may be provided adjacent to a cooling-only coil 26b. This is the same configuration as a conventional cooling and heating ('<NUM>-pipe') fan coil unit. However, this has the disadvantage of increasing the coil pressure drop, and thereby increasing energy use and decreasing the overall air conditioning unit efficiency.

The present arrangement is a two-row coil 26b, split into three sections on each of three sides of the air conditioning unit <NUM>. This is merely exemplary and other numbers of section and/or rows could be used, for example air inlets <NUM> and corresponding sections of the coil 26a may be provided only on two sides. Also one-row or three-row coils 26a may be appropriate depending on the duty.

<FIG> shows an HVAC infrastructure for supplying cooling or heating medium to a plurality of air conditioning units <NUM>. Within the infrastructure, the cooling system <NUM> for the air conditioning unit <NUM> is generally independent from the heating system <NUM>. First the cooling system <NUM> will be described.

The cooling system <NUM> comprises a condenser <NUM>, such as a cooling tower, and a chiller <NUM>. The cooling medium (e.g. water) for the air conditioning units <NUM> is cooled by the chiller <NUM> and the heat is dissipated by the condenser <NUM>.

Conventional fan coil operating temperatures are in the region of about <NUM> flow and about <NUM> to <NUM> return. However, these temperatures will give rise to condensation under the majority of room conditions, and a condensate removal system must therefore be included.

An alternative approach is to use higher water temperatures, typically <NUM> to <NUM> flow and <NUM> to <NUM> return, in order to avoid condensation. These temperatures will not give rise to condensation under the majority of room conditions (although a condensate removal system is typically still included).

The present air conditioning unit <NUM> has been selected to have the option to run using low energy sources which are non-refrigerated, with temperatures of <NUM> flow and <NUM> return, though other operational temperatures could be used.

During one mode of operation, the cooling medium is cooled to flow temperature using the chiller <NUM>. In another mode of operation, water from the condenser <NUM> (the cooling tower) can be used directly as a refrigerated source. In the UK it is possible to run such an arrangement for a significant portion of the year using the condenser water from the cooling tower <NUM> for cooling directly. To deliver a design flow temperature of <NUM> directly from a cooling tower, the ambient wet bulb temperature would have to be <NUM> or lower, based on a tower size, to give a <NUM> difference between the wet bulb and the flow temperature. In London, for example, ambient wet bulb temperatures are below <NUM> at least <NUM>% of the hours in the year.

Thus, in the winter, the water from the cooling tower <NUM> could be connected directly to the air conditioning unit <NUM> by connecting cooling tower flow and return valves 42a, 42b to respective cooling circuit system flow and return valves 44a, 44b. In the summer, the cooling tower <NUM> would connect to the chiller <NUM>, with condenser water temperatures of, for example, <NUM> flow and <NUM> return. The chiller <NUM> would generate chilled water at the desired temperatures.

Other sources of low energy cooling water may also be used, for example the cooling tower <NUM> may be replaced or supplemented by using, for example, river water and/or ground water.

If a water-cooled chiller <NUM> is used for the cooling options, at high ambient temperatures, e.g. operating at temperatures of <NUM> / <NUM>, the refrigeration circuit can be arranged to provide condenser water from the cooling tower <NUM> to the heating system <NUM> by connecting the cooling tower flow and return valves 42a, 42b to respective heating circuit system flow and return valves 46a, 46b. This can be used for heat recovery, providing 'free' heating to the air conditioning units <NUM> that require heating.

As discussed above, even where relatively high operating temperatures are used to minimise condensation, it is still common to include a condensate removal system <NUM> (although this could be omitted if desired). Use of a condensate removal system <NUM> then allows the air conditioning unit <NUM> to be operated at lower temperatures, if desired. It also means that the unit <NUM> can be used in a mixed mode building, i.e. where natural ventilation is used for parts of the year. (In a fully air conditioned building with a sealed façade the humidity can be kept to a low figure, such as <NUM>% RH, to avoid condensation. In a naturally ventilated building this is not possible, and a humidity of up to <NUM>%RH may occur, which would cause condensation on a cold surface such as an air conditioning unit cooling coil).

<FIG> shows a condensate removal system <NUM> for the air conditioning unit <NUM>. <FIG> shows a longitudinal section through the condensate removal system <NUM>, and <FIG> shows a transverse section through the condensate removal system <NUM>.

Due to the shallow depth of the air conditioning unit <NUM>, gravity drainage may not be feasible. When gravity drainage is not possible and condensate removal is required it must be by pumping. The condensate removal system comprises a condensate pump <NUM> and a drip tray <NUM>, made of for example plastic, aluminium or other suitable material, provided below one or more cool elements of the unit <NUM>, such as portions of the cooling coil 26b and/or the cool water control valves 32a, 32b. The condensate pump <NUM> is preferably of the variable geometry type, which does not require a sump or float switch. The pump <NUM> will run slowly to remove condensate as it collects in the drip tray <NUM>, in contrast to a centrifugal pump which requires a sump and only pumps the condensate after a sufficient quantity has accumulated.

A hydrophilic condensate collection member <NUM>, for example in the form of a pipe with a hydrophilic coating, is provided, which preferably runs the length of the drip tray <NUM>. The hydrophilic coating allows water to pass through the coating but not air. This means that the member <NUM> will collect condensate at any point along its length.

A moisture sensor <NUM>, for example a moisture sensitive conductor is also provided, which also preferably runs the length of the drip tray <NUM>. If a moisture above a threshold moisture level is detected, then the pump <NUM> is activated. The condensate control system <NUM> may also have an override to turn off the chilled water supply and fan <NUM> in the event that the condensate accumulates, for example if there is a fault.

By use of this condensate control system <NUM>, all condensate is trapped by the hydrophilic member <NUM> and then pumped out of the air conditioning unit <NUM> by the pump <NUM>.

The air conditioning unit <NUM> is designed to be installed in two phases, corresponding to first fix and second fix. First, an installation frame <NUM> is installed at the time of first fix. The installation frame <NUM> is shown in section in <FIG> and in plan in <FIG>. The main body <NUM> of the air conditioner unit <NUM> is then installed in second fix, shown in <FIG>.

The installation frame <NUM> comprises a rigid body portion <NUM> adapted to be mounted to the soffit of the ceiling during a first fix. The rigid body portion <NUM> further comprises raised sections <NUM>, preferably adjacent the corners of the body portion <NUM>, adapted to receive threaded rods <NUM>, for example via internally-threaded through holes. The threaded rods <NUM> provide the frame <NUM> with means for mounting the main body <NUM> of the air conditioning unit <NUM> to the installation frame during the second fix.

The installation frame <NUM> may further comprise fluid connection points <NUM> for certain services <NUM>, such as inlet and outlet cooling/heating medium pipes 18a, 18b, to be attached the installation frame <NUM>. <FIG> illustrates one pair of pipes - as described before there may be two pairs if a there is a <NUM> pipe system. Within the installation frame <NUM> may also be provided flexible connections <NUM> for linking the fluid connection points <NUM> of the installation frame <NUM> to the main body <NUM> of the air conditioning unit <NUM>, when it is installed during the second fix. The connection points <NUM> should each include an isolation valve <NUM> to allow the main body <NUM> of an individual air conditioning unit <NUM> to be removed without shutting down services to a larger network.

Similarly, the installation frame <NUM> may also comprise electrical connection points <NUM> for other services <NUM>, such as power and control cables, to be attached to the installation frame <NUM>. The electrical connection points <NUM> may each comprise a fused spur and interface box.

The flexible pipes and cables are preferably located to be sufficiently short for them to be accessed by hand from below through the main body of the air conditioning unit when it is open in 'self-access' mode.

The following sequence is recommended for installation:.

There are many components in a typical false ceiling, and some require more access than others. Typically the chilled water (CHW) & low-temperature hot water (LTHW) pipework, sprinkler pipework, cable trays and cables will be installed as first fix items, and will remain relatively unchanged until there is a major fit-out. These components are unlikely to require access once they have been installed.

The components that typically do require access, either for commissioning after the ceilings are up, or later for maintenance, include lamps, smoke detectors, and the HVAC components, such as balancing dampers, balancing valves, fan coil filters and control boxes. These components are accessed in traditional installations with either access panels or a fully accessible ceiling. Conversely, the air conditioning unit <NUM> described herein is arranged to provide self-access, as illustrated in <FIG>.

The main body <NUM> of the air conditioning unit <NUM> is composed of two housing portions <NUM>, <NUM>. The first housing portion <NUM> is mounted to the ceiling, for example via the installation frame <NUM>. The second housing portion <NUM> is attached to the first housing portion <NUM> via a hinge such that it can be rotated from an operational position (as in <FIG>) to a maintenance position (shown in <FIG>). When moving into the maintenance position, the second housing portion <NUM>, which includes the front face of the main body <NUM>, swings into the thermally controlled space <NUM> to provide access to the components of the air conditioning unit <NUM>.

The thermal elements <NUM> are mounted within the first housing portion <NUM>. This means that the cooling/heating medium supply does not need to be disconnected when maintenance is being performed on the air conditioning unit <NUM>.

The fan <NUM>, fan plate <NUM> and motor are mounted within the second housing portion <NUM> such that they swing down with the second housing portion <NUM> when it is moved into the maintenance position. This allows a worker performing maintenance (when using a ladder) to work at eye level in front of him, rather than working on a unit <NUM> above his head, as has been the case with traditional fan coil units that could be maintained in situ. This working position is safer and more comfortable.

The fan <NUM> may include a fan control box <NUM>, which is also mounted on the second housing portion <NUM>. A display of the fan control box <NUM> can then be arranged to be easily read by the worker doing the maintenance or commissioning. Again, this can be read easily at eye level, rather than requiring the worker to look upwards when working.

In the maintenance position, the various motorised valves (such as changeover valves 32a, 32b and isolating valves <NUM>) of the air conditioning unit <NUM> are easily accessible as the fan has been moved out of the way with the second housing portion <NUM>. The condensate pump <NUM> and drip tray <NUM>, which are also mounted to the first housing portion <NUM>, are similarly easily accessible.

The filters <NUM> are positioned such that they can slide vertically downwards for cleaning or changing in the maintenance position.

As illustrated in <FIG>, the air conditioning unit <NUM> can be disconnected and dropped out of the ceiling if required. To do this, the second housing portion <NUM> is swung down into the maintenance position, the connections to power, cooling/heating medium and condensate are isolated (via valves <NUM>) and the flexible connections <NUM> disconnected, and the four corner fixing bolts <NUM> are unscrewed from the first housing portion <NUM> to disconnect it from the installation frame <NUM>. The whole air conditioning unit <NUM> can then be carefully dropped out of the ceiling.

<FIG> and <FIG> show exemplary ceiling layouts incorporating the air conditioning unit <NUM>.

In the <FIG> layout, the light fixtures <NUM> are arranged to provide one light fixture <NUM> per <NUM><NUM> and the air conditioning units <NUM> are arranged to provide one air conditioning unit <NUM> per <NUM><NUM>.

In the <FIG> layout, the light fixtures <NUM> are arranged to provide the same lighting density as in the <FIG> layout, but the air conditioning units <NUM> are arranged to provide one air conditioning unit <NUM> per <NUM><NUM>. Furthermore, a greater density of air conditioning units <NUM> is provided at the periphery of the building (righthand side of <FIG>) to account for fabric load (external conditions).

<FIG> illustrate various alternative arrangements of the air conditioning unit <NUM> discussed above with reference to <FIG>. Except for the differences discussed below, the configurations of the following alternative air conditioning units are the same as in the air conditioning unit <NUM> discussed above.

<FIG> shows an air conditioning unit <NUM> in which the main body <NUM> of the air conditioning unit <NUM> is the same as the main body <NUM> of the first air conditioning unit <NUM> shown in <FIG>.

In <FIG>, the air conditioning unit <NUM> has been installed in a ceiling having a more conventional ceiling depth of around <NUM>. The main advantage of this is that it permits the use of a ducted outside air supply 118a, rather than using a plenum floor supply <NUM> as used by the air conditioning unit <NUM> shown in <FIG>.

<FIG> shows an example of an air conditioning unit <NUM> not falling under the present invention in which the thermal element <NUM> comprises a chilled beam <NUM>. The use of a chilled beam <NUM> provides a very large area thermal element. This increases thermal conduction between the airflow and the thermal element <NUM>, as well as reducing the pressure drop across the thermal element <NUM>.

Whilst this configuration requires a thicker unit <NUM>, as in <FIG>, this then permits the use of a ducted outside air supply 218a.

In this arrangement, the air inlets <NUM> are still arranged at the side faces of the air conditioning unit <NUM>, about its periphery. The air is drawn into the air conditioning unit <NUM> horizontally via the air inlets <NUM>, and then drawn vertically downwards through an air filter <NUM> and then through the chilled beam <NUM> by the fan <NUM>. It is then output by the fan <NUM> in a swirl pattern into the temperature controlled space <NUM>.

Where a chilled beam <NUM> is used instead of a cooling coil 26b, certain modification may be made to the condensate removal system. In this air conditioning unit <NUM>, a condensate shield 254a is provided above the fan <NUM> to prevent condensate falling into the fan <NUM>. A condensate tray <NUM> is arranged vertically below the chilled beam <NUM>, i.e. across the rear of the front face, to collect condensate from the chilled beam <NUM>. The condensate shield 254a is arranged to direct condensate that would fall into the fan <NUM> into the condensate tray <NUM>.

As above, a hydrophilic member is provided within the condensate tray <NUM> to collect the condensate, and a condensate pump <NUM> is used to draw the condensate along the hydrophilic member and out of the air conditioning unit <NUM>.

<FIG> shows pendant suspension configuration, in which a main body <NUM> of an air conditioning unit <NUM> is suspended from the ceiling. This may be appropriate for retail use, or restaurants, with exposed ceilings. There is also a move in office design towards removing suspended ceilings and having exposed services and suspended units.

In this configuration, the side faces of the main body <NUM> comprise perforated facia panels <NUM>, which may be hinged to permit access to the filters around the periphery of the front face of the main body <NUM>.

The internal structure of the main body <NUM> of the air conditioning unit is unchanged from that of the main body <NUM> of the air conditioning unit <NUM> shown in <FIG>. Particularly, as discussed above, the air discharges straight from the tips of the fan blades in a pattern that spreads out in a circular flow. As the air flow pattern does not depend on the coanda effect from the adjacent ceiling, the air conditioning unit <NUM> can be pendant mounted whilst still achieving the same air flow pattern as the unit <NUM> mounted in the ceiling.

<FIG> illustrates a modification that can be incorporated into any of the air conditioning units discussed herein.

In this arrangement, the inclined surface of the fan plate <NUM> is used as a diffuser to bounce the intense light from LED sources <NUM>, to produce a diffuse lighting effect in the space below. The perforated plate <NUM> covering the complete underside of the air conditioning unit is not present in this arrangement - the plate is solid, and reduced in width to the minimum needed to cover the fan and support the LED sources <NUM>. An advantage of integral lighting when applied to an exposed pendant version of the air conditioning unit <NUM> is that the unit <NUM> may be perceived as a light fitting, rather than as an unlit suspended shape.

<FIG> show a further exemplary ceiling layout incorporating this air conditioning unit <NUM>. In order to provide the desired lighting density, one air conditioning unit <NUM> per <NUM><NUM> is provided. However, this is not visually obtrusive as the air conditioning units <NUM> is not perceived as such.

<FIG> illustrate an air conditioning unit <NUM> which is a variation of the pendant air conditioning unit <NUM> shown in <FIG>.

The main body <NUM> of the air conditioning unit <NUM> is suspended from the ceiling. The air conditioning unit <NUM> further comprises a rim member <NUM>. The rim member may comprise downward-directed lights <NUM> and/or upward-directed lights <NUM>.

The air conditioning unit <NUM> is arranged to be visually appealing by having a relatively wide unit <NUM> with a slim profile. The intention is for the visible depth, i.e. the height of side panels <NUM> of the rim member <NUM>, to be about <NUM>% of the width of the air conditioning unit <NUM>. As can be seen in <FIG>, the rear face of the rim member <NUM> is sloped such that the sloping back panels will be hard to see from below. In this example, the side panels <NUM> of the rim member <NUM> have a height of about <NUM> and the rim member <NUM> has a width of <NUM>. This results in an air conditioning unit <NUM> having apparent dimensions of about <NUM> x <NUM> x <NUM>.

The side panels <NUM> and facia plate <NUM> preferably have a high quality finish, such as stainless steel. To provide a "clean" appearance, the back panels of the rim member <NUM> may comprise perforated air inlets <NUM> to allow air to be drawn in on the non-visible upper side, through the rim member <NUM> into the air inlets <NUM> of the main body <NUM>.

<FIG> illustrate a multi-service air conditioning unit <NUM> which is a variation of the pendant air conditioning unit <NUM> shown in <FIG>.

There has been a trend to use multi-service units <NUM> in offices, incorporating all of the MEP components required in a single unit. The multi-service air conditioning unit <NUM> has a rim member <NUM> that provides lighting <NUM>, as well as various other services <NUM>, such as smoke or heat detectors, sprinklers, public announcement / voice alarm loudspeakers, and/or PIR detectors.

<FIG> show a vertical air conditioning unit. The air conditioning unit is the same as the air conditioning unit <NUM> shown in <FIG>, except that the condensate removal system <NUM> is modified so as to provide a drip tray spaced vertically below the thermal elements and a coil provided at an oblique angle.

The coils <NUM> are again provided on three sides. They are arranged so that condensate can be collected from each of the three coils. The top side of the unit contains the fan controls, the control valves and the condensate pump. There may be provided an upper small drip tray below this section, with a branch of the hydrophilic drain pipe.

The two side coils <NUM>, which extend substantially vertically, have the same size and duty as in the air conditioning unit <NUM> shown in <FIG>. The lowest of the three coils, which extends substantially horizontally, is, in contrast, smaller in length and height, and is fitted at an angle of approximately <NUM> degrees from the vertical, as seen most clearly in <FIG>. The air flow enters the lower surface of the air conditioning unit across the whole width of the filter <NUM>, which permits the pressure drop to remain low. The air passes to the side of the drip tray below the coil, through the coil and then up into the unit, as indicated by the arrows in <FIG>. The coil is angled at approximately <NUM> degrees from the vertical to permit the air to flow at an angle into the unit, in a region that is not covered by the drip tray. As seen in <FIG>, the drip tray <NUM>, which is substantially planar (except for vertically projecting side walls) has an elongated central portion that extends across the entire width of the angled coil <NUM> and end portions that project from the ends of the central portion to lie entirely under the vertically extending side coils <NUM>. Any condensate that forms on the face of the angled coil <NUM> will run down the face of the angled coil into the drip tray, to be caught by the central portion thereof. Any condensate that forms on the face of the vertically extending side coils will be collected by the end portions. Whilst, an angle of <NUM> degrees is stated here for the angled coil <NUM>, various alternative oblique angles will provide the desired effect.

The cooling coil pipework connections between the side coils and the angled lower coil are intricate. The pipes on the upstream face in the vertically extending side coil are connected to the pipes on the upstream face in the horizontal angled coil, and then back to the upstream face on the opposite vertically extending side coil. The same applies to the downstream pipes. This keeps the pipework connection arrangement the same as shown in the arrangement of <FIG>.

A branch of the hydrophilic drain pipe runs down from the condensate pump at the top of the unit to remove condensate from the lower tray. In alternative arrangements, a gravity arrangement may be used to remove condensate from the two drip trays instead.

A void may be provided above, below or to the side of the unit to allow a return air path. Outside air can be ducted or supplied by a separate means.

It should be appreciated, whilst allowing for the angled coil and alternative condensate collection arrangement that any adaptations or alternatives stated in respect of the embodiments described above may be applied to the vertical arrangement described with reference to <FIG>.

Vertical air conditioning units could be used in hotel or conference centre function rooms, in residential buildings, offices or schools. They could be located below window sills, they could further be used in underground transit stations/platforms and to cool computer rooms.

One option would be to use a <NUM> deep zone, as with the ceiling-based air conditioning unit <NUM>. The face velocity, if based on <NUM><NUM>/sec and a 600x600 diffuser, would be <NUM>/s face velocity, which would be too high for some applications. However, if the depth of the unit <NUM> is increased to <NUM> to <NUM> and a diffuser plate <NUM> is used, then the face velocity can be reduced to <NUM>/s. If the supply temperature was also to be set at <NUM>, then the unit <NUM> would reproduce the supply conditions of a displacement diffuser, which is known to give acceptable comfort for occupants near the diffuser.

If an array of vertical air conditioning units <NUM> is installed in a wall it is possible to achieve the cooling loads need to cool for example a small computer room, such as an SER (Small equipment Room) or SCR (Sub Comms Room), with a single row of racks <NUM>. This arrangement is illustrated in <FIG>.

In the example sketched, with three computer racks <NUM> with a conventional cooling load of <NUM> kW each, the loads and cooling capacity will be:.

The cooling capacity far exceeds the requirement of standard racks, and high density racks of <NUM> kW each could be accommodated.

Claim 1:
An air conditioning unit (<NUM>), comprising:
a main body (<NUM>) including an air inlet (<NUM>) and an air outlet (<NUM>), the main body (<NUM>) defining an airflow passage between the air inlet (<NUM>) and the air outlet (<NUM>);
a fan (<NUM>) disposed within the airflow passage; and
a thermal element (<NUM>) disposed within the airflow passage upstream of the fan (<NUM>),
wherein the main body (<NUM>) has a first face on which the air outlet (<NUM>) is disposed,
wherein the air inlet (<NUM>) and thermal element (<NUM>) are disposed at the periphery of the first face,
wherein the fan (<NUM>) is oriented such that the rotational axis of the fan (<NUM>) is substantially perpendicular to the first face,
wherein the first face is adapted so as to be exposed, in use, to a temperature-controlled space,
wherein blades of the fan (<NUM>) are designed so that the air conditioning unit (<NUM>) provides a swirling air flow pattern with the air discharged straight from tips of the blades of the fan (<NUM>) into the temperature controlled space in a pattern that spreads out in a circular flow,
the thermal element (<NUM>) is mounted to a first housing portion (<NUM>) of the main body (<NUM>) and the fan (<NUM>) is mounted to a second housing portion (<NUM>) of the main body (<NUM>), the second housing portion (<NUM>) being hinged with respect to the first housing (<NUM>), and
the second housing portion (<NUM>) is rotatable via the hinge with respect to the first housing portion (<NUM>) from a first position to a second position, and wherein the fan (<NUM>) is operable for normal use in the first position and is accessible for maintenance in the second position.