DIFFUSER MODULE

Abstract

Disclosed herein is a diffuser module that can be used to air condition a space. The space may comprise the interior space(s) of buildings such as hospitals, enclosed shopping malls, warehouses, factories, etc. The module may comprise a body defining an interior chamber, the body having an upper end able to be connected to the air conditioning unit (AHU) and an opposing lower end. The module may also comprise a first channel disposed in the chamber for receiving a first air stream from the unit. The module may also comprise at least one diffuser connected to the lower end of the body, the at least one diffuser able to receive the first air stream from the first channel and discharge it to the space.

Claims

1. A diffuser module for connection to an air conditioning cooling or heating unit arranged to condition air in a space, the module comprising; a body defining an interior chamber, the body having an upper end able to be connected to the air conditioning unit and an opposing lower end; a first channel disposed in the chamber, the first channel having an inlet at an in-use upper end of the channel for receiving a first air stream from the unit in a first direction, and an outlet at an in-use lower end of the channel for discharging the first air stream in the first direction; and at least one diffuser connected to the lower end of the body adjacent to the outlet of the first channel to receive the first air stream from the first channel in the first direction and to discharge the first air stream to the space; wherein the at least one diffuser is able to discharge to the space at least a portion of the first air stream at a substantially constant discharge velocity or throw when the airflow rate of the first air stream is varied.

2. A diffuser module according to claim 1, wherein the at least one diffuser is a high induction swirl diffuser, and wherein a central axis of the swirl diffuser is parallel to or aligned with a longitudinal axis of the module.

3. (canceled)

4. A diffuser module according to claim 1, wherein the upper end comprises a mounting flange that facilitates attachment of the body to a support structure of a building, optionally the support structure is a roof and, in use, the lower end of the body is suspended below the roof of the building and defines an underside of the body.

5. A diffuser module according to claim 1, further comprising a second channel disposed in the chamber for returning a second air stream from the space to the unit.

6. A diffuser module according to claim 1, wherein the direction of the first air stream discharged by the at least one diffuser is adjustable, and wherein the discharge direction of the first air stream is able to be adjusted between a first direction, which lies in a first plane that is substantially parallel to the face of the diffuser, and in a second direction that is substantially perpendicular to the face of the diffuser.

7. A diffuser module according to claim 1, wherein the at least one diffuser is configured to discharge at least a portion of the first air stream substantially parallel to the face of the diffuser at a substantially constant discharge velocity when the airflow rate of the first air stream is adjusted.

8. A diffuser module according to claim 1, wherein the at least one diffuser is configured to discharge at least a portion of the first air stream substantially parallel to the face of the diffuser with a substantially constant throw when the airflow rate of the first air stream is adjusted.

9. A diffuser module according to claim 4, wherein the at least one diffuser is a high induction swirl diffuser, wherein a central axis of the swirl diffuser is parallel to or aligned with a longitudinal axis of the module, wherein the swirl diffuser comprises primary vanes, each configured to rotate about a substantially radial axis that extends radially out from the central axis of the swirl diffuser, and wherein the airflow direction discharged by the swirl diffuser is adjustable within a first range of rotation of at least one primary vane, and wherein the airflow rate discharged by the swirl diffuser, for a constant total supply air pressure, may be adjustable within a second range of rotation of at least one primary vane.

10. A diffuser module according to claim 9, wherein, the first range of rotation varies between: an airflow direction of the first air stream being discharged to be substantially perpendicular to the face of the diffuser for a steep angle of primary vane rotation; and an airflow direction of the first air stream being discharged to be substantially parallel to the face of the diffuser for a shallower angle of primary vane rotation; whereby the steep angle of rotation is greater than the shallower angle of rotation relative to the face of the diffuser.

11. A diffuser module according to claim 9, wherein within the second range of rotation of the at least one primary vane the airflow direction of the first air stream discharged by the diffuser is substantially parallel to the face of the diffuser.

12. A diffuser module according to claim 9, wherein within the second range of rotation, the airflow rate discharged by the diffuser varies between a substantially maximum airflow rate at a steep angle of rotation and a substantially minimum airflow rate at a shallow angle of rotation, and wherein the steep angle of rotation is greater than the shallow angle of rotation of the at least one primary vane relative to the face of the diffuser.

13. A diffuser module according to claim 9, wherein the steep angle of rotation of the at least one primary vane in the first range of rotation is greater than the steep angle of rotation of the at least one primary vane in the second range of rotation relative to the face of the diffuser.

14. A diffuser module according to claim 9, wherein the first range of rotation is employed when the first air stream temperature is warmer than the air in the space, and wherein the second range of rotation is employed when the first air stream is cooler than the air in the space.

15. A diffuser module according to claim 9, wherein the swirl diffuser further comprises at least one secondary vane; the at least one secondary vane is arranged to discharge a secondary airstream such that it generally flows from the diffuser in a plane that is substantially parallel to the face of the diffuser; and the at least one primary vane is arranged to discharge a primary airstream that is able to be induced by the secondary airstream such that the direction of the primary airstream is able to be substantially determined by the direction of travel of the secondary airstream.

16. A diffuser module in according to claim 15, wherein rotation of the at least one primary vane is able to vary the airflow rates of the secondary airstream and of the primary airstream, and wherein rotation of the at least one primary vane is able to vary the airflow rates of the primary airstream and of the secondary airstream substantially independently of one another.

17. A diffuser module according to claim 16, wherein; a given rotation of the at least one primary vane in a portion of the second range of rotation is able to reduce the airflow rate of the primary airstream without substantially changing the airflow rate of the secondary airstream; and a given rotation of the at least one primary vane within a portion of the first range of rotation is able to reduce the airflow rate of the secondary airstream without substantially changing the airflow rate of the primary airstream.

18. A diffuser module according to claim 15, wherein the direction of the first air stream discharged by the at least one diffuser is adjustable, and wherein the discharge direction of the first air stream is able to be adjusted between a first direction, which lies in a first plane that is substantially parallel to the face of the diffuser, and in a second direction that is substantially perpendicular to the face of the diffuser, and wherein the airflow rate of the first air stream discharged by the swirl diffuser remains substantially constant, for a constant total supply air pressure, across a given range of airflow direction adjustment, and optionally wherein the primary vanes each have an equal angular extent of rotation.

19. A diffuser module according to claim 9, wherein, when viewed along the longitudinal axis, the predominant airflow pattern discharged by the swirl diffuser covers an are of 360°, and optionally wherein at least one of the primary vanes is able to be fixed at a shallow angle of rotation within the second range of rotation, while the other primary vanes can remain rotatable or are able to be fixed at an angle greater than the shallow angle such that, when viewed along the longitudinal axis, the predominant airflow pattern discharged by the swirl diffuser covers an arc of less than 360°, and optionally wherein the diffuser module further comprises at least one removable blocking element which is able to substantially block the air path to the at least one fixed primary vane, such that it is able to substantially reduce the airflow discharged by that fixed primary vane.

20. A diffuser module according to claim 9, further comprising a crown gear configured to rotate about the central axis of the diffuser, the crown gear being further configured to engage and rotate at least one bevel gear connected to a respective primary vane to thereby rotate the primary vane about its substantially radial axis.

21. A diffuser module according to claim 9, wherein in profile, the primary vane comprises a planar surface and an angled lip along its trailing edge, such that when the primary vane is closed, the angled lip is orientated at a greater angle to the face of the diffuser relative to the angle between the planar surface and the face of the diffuser.

22. A diffuser module according to claim 1, wherein the upper end of the body is profiled to fit within an aperture in a roof, the upper end having a mounting flange that facilitates attachment of the diffuser module to a support structure located at the roof aperture, and optionally wherein the upper end of the body is able to provide support for an end of the unit, or optionally wherein the upper end of the body is profiled to fit within an aperture in a wall, the upper end having a mounting flange that facilitates attachment of the diffuser module to a support structure of the wall.

23. A method of installing an HVAC system in the roof or wall of a building, the method comprising; fabricating supporting framework protruding as a flange from a diffuser module; lowering or positioning the diffuser module through a hole in a structure of the building until the flange rests on the structure of the building surrounding the hole, the diffuser module comprising: a body defining an interior chamber, the body having an upper end able to be connected to an air conditioning unit and an opposing lower end, the upper end being configured to receive a first air stream from the air conditioning unit in a first direction; the lower end being configured for discharging the first air stream in the first direction through an outlet; and at least one diffuser mounted to the lower end of the body adjacent to the outlet to receive the first air stream from the body interior chamber and discharge the first air stream to a space; the method further comprising securing the air conditioning unit outside the roof or wall to the structure of the building such that the unit is in communication with the diffuser module; and wherein the at least one diffuser is mounted to the lower end of the body when lowered or positioned through the hole in the roof or wall.

24. A method of installing an HVAC system in accordance with claim 23, wherein the diffuser module the at least one diffuser of the diffuser module is able to discharge to the space at least a portion of the first air stream at a substantially constant discharge velocity or throw when the airflow rate of the first air stream is varied.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Embodiments will now be described by way of example only, with reference to the accompanying drawings in which

[0067] FIG. 1 shows a side view of the diffuser module fitted to a packaged air conditioning system that is located on a roof of a building;

[0068] FIG. 2 shows a cross section through the diffuser module of FIG. 1;

[0069] FIG. 3 shows a bottom view of the diffuser module;

[0070] FIG. 4 shows a perspective view of the diffuser module shown in FIG. 3.

[0071] FIG. 5 shows a bottom view of another embodiment of the diffuser module;

[0072] FIG. 6 shows a perspective view of the diffuser module shown in FIG. 5;

[0073] FIGS. 7a-d show cross sections through the diffuser with the primary vane rotated through four different positions;

[0074] FIG. 8 shows a perspective view from the top of a diffuser component with the primary vane closed;

[0075] FIG. 9 shows a perspective view from the top of the diffuser component of FIG. 8 with the primary vane partially open;

[0076] FIG. 10 shows a perspective view from the top of the diffuser component of FIG. 8 with the primary vane completely open;

[0077] FIG. 11 shows a perspective view from the top of the diffuser with the diffuser components installed in a plate;

[0078] FIG. 12 shows a perspective view from the bottom of the diffuser of FIG. 11 with the diffuser components installed in the plate;

[0079] FIG. 13 shows a cross section of the diffuser module attached to the roof structure of a building;

[0080] FIG. 14 shows another embodiment of the diffuser module attached to the roof structure of a building;

[0081] FIG. 15 shows an embodiment of the primary vane that is twisted;

[0082] FIG. 16 shows an embodiment of the diffuser with 360° discharge;

[0083] FIG. 17 shows an embodiment of the diffuser with 360° discharge for a reduced airflow rate range;

[0084] FIG. 18 shows an embodiment of the diffuser with less than 360° discharge;

[0085] FIG. 19 shows a cross section of the primary vane with angled trailing edge lip;

[0086] FIG. 20 shows an isometric view from below of an alternative embodiment of the diffuser;

[0087] FIG. 21 shows an isometric view from above of the diffuser shown in FIG. 20;

[0088] FIG. 22 shows an another isometric view from above of the diffuser shown in FIG. 20; and

[0089] FIG. 23 shows a section through the diffuser shown in FIG. 20.

DETAILED DESCRIPTION

[0090] In the following detailed description, reference is made to accompanying drawings which form a part of the detailed description. The illustrative embodiments described in the detailed description, depicted in the drawings and defined in the claims, are not intended to be limiting. Other embodiments may be utilised and other changes may be made without departing from the spirit or scope of the subject matter presented. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings can be arranged, substituted, combined, separated and designed in a wide variety of different configurations, all of which are contemplated in this disclosure.

[0091] Disclosed herein is a diffuser module for connection to an air conditioning cooling or heating unit arranged to condition air in a space. Referring firstly to FIGS. 1 and 2, the diffuser module 1 will be described in detail. The diffuser module, in the form of a basket dropper 1, comprises a body in the form of a duct 3 that defines an interior chamber 5. The duct 3 has an upper end 7 able to be connected to the air conditioning unit 9 and an opposing lower end 11. The basket dropper 1 includes a first channel, in the form of supply air plenum 13, disposed in the duct 3 for receiving a first air stream, in the form of supply air 15, from the unit 9. The basket dropper 1 also includes at least one diffuser 17 (see also FIGS. 3 to 6) connected to the lower end 11 of the body. The diffuser 17 is able to receive the supply air 15 from the supply air plenum 13 and discharge it to the interior space 19, such as an interior space warehouse. Supply air 15 may flow to the diffuser 17 via a perforated baffle plate 13a located in supply air plenum 13. The diffuser 17 is able to discharge at least a portion of the supply air stream 15 at a substantially constant discharge velocity when the airflow rate of the supply air stream 15 received from the unit is varied. As such, the basket dropper 1 is able to operate as a variable air volume (VAV) diffuser.

[0092] The supply air plenum 13 is arranged to receive the supply air 15 from the unit 9 in a first direction (represented in FIG. 2 as supply air stream 15A). The diffuser 17 is arranged to receive the supply air stream 15 from the supply air plenum 13 in the same direction (represented in FIG. 2 as supply air stream 15B). In other words, the supply air stream 15 does not substantially change its direction in the supply air plenum 13 between the inlet adjacent the upper end 7 and the outlet at the lower end 11. Perforated baffle plate 13a reduces the turbulence and improves the uniformity of supply air stream 15B as it flows onto diffuser 17. The configuration of the diffuser 17 allows for the supply air stream 15 to be discharged in a plane that is parallel with the face of the diffuser.

[0093] Supply air plenum 13 may be internally lined with thermally insulating and acoustically absorbing material, to prevent thermal bridging of the temperature differential between the supply air stream and the interior space 19, as well as to attenuate noise from the supply air fan in the unit 9.

[0094] As shown in FIGS. 3 to 6, the upper end 7 of the duct 3 includes a mounting flange 21 that facilitates attachment of the duct 3 to a support structure of a building. In the described embodiments, the support structure is a roof 23. In use, the lower end 11 of the duct 3 is suspended below the roof 23 of the building and defines an underside of the duct 3.

[0095] The basket dropper 1 can be lowered into the roof 23 by a crane through a hole in the upstand 23a on the roof 23 until the protruding flange 21 of the basket dropper 1 rests on, and seals onto, the upstand 23a, which, in turn, is connected beneath the roof 23 to the structure of the roof (i.e. roof beams). This is described in further detail with reference to FIG. 13. The basket dropper 1 may also include a second channel, in the form of a return air plenum 25, disposed in the duct 3, for returning the return air 27 from the space 19 to the unit 9. Advantageously, including the return and supply air plenums within a single duct saves on space requirements and the quantity of ducting associated with the installation of the HVAC system. However, if required, the return air plenum 25 can be manufactured and installed separately to the supply air plenum 13 and duct 3. Optionally, the return air plenum 25 can be formed from fire resistant material such that it can be used to exhaust smoke from the space in the event of a fire. This arrangement saves on the space requirements and capital costs associated with the installation of a dedicated smoke extraction system. A divider wall 24 is located within the duct 3 to separate the supply air plenum 13 from the return air plenum 25. A return air grille 26 is located about the periphery of the duct 3 and at the underside 28 of the rectangular top portion 30 of the basket dropper 1. As shown in FIGS. 6 and 8, the return air grille 26 can be located around the whole duct 3 for aesthetic reasons. The portion of the grille 26 that is located adjacent the supply air plenum 13 is internally covered with a blanking strip to ensure that no supply air passes through the return air grill 26.

[0096] Return air plenum 25 may be internally lined with acoustically absorbing material to attenuate noise from the supply air fan in the unit 9.

[0097] As will now be described with reference to FIGS. 7a-d, the direction of the supply air stream 15 discharged by the diffuser 17 is adjustable. The discharge direction of the supply air stream 15 is able to be adjusted between a first direction A, which lies in a first plane that is substantially parallel to the face 27 (see also FIGS. 3 to 6) of the diffuser 17, and in a second direction B that is substantially perpendicular to the face 27 of the diffuser 17.

[0098] The diffuser 17 is configured to discharge at least a portion of the supply air stream 15 at a substantially constant discharge velocity substantially in direction A when the airflow rate of the supply air stream 15 supplied from the unit is adjusted. The diffuser 17 is also configured to discharge at least a portion of the supply air stream 15 with a substantially constant throw substantially in direction A when the airflow rate of the supply air stream 15 supplied from the unit is adjusted. In the detailed embodiments, the diffuser 17 is a high induction swirl diffuser. The swirl diffuser is positioned such that a central axis C (see FIGS. 3 and 11) of the swirl diffuser 17 is parallel to a longitudinal axis D (see FIG. 2) of the module. When installed in the roof 23 of a building, the longitudinal axis D is substantially vertical in orientation. In the detailed embodiments, the central C and longitudinal D axes are coincident.

[0099] The swirl diffuser 17 includes primary vanes 31 configured to rotate about radial axes that extend out from the central axis C of the diffuser (see E1 to E6 in FIG. 3). The radially aligned axes E1 to E6 emanate/extend from, and are substantially perpendicular to, the central axis C and coincident longitudinal axis D. The airflow direction of the supply air stream 15 discharged by the swirl diffuser 17 is adjustable in a first range of rotation of the primary vanes 31. For the first range of rotation, the airflow direction of the supply air stream 15 discharged by the swirl diffuser 17 is substantially perpendicular B to the face 17a of the diffuser 17 for a steep angle of rotation (as shown in FIG. 7b), and substantially parallel A to the face 27 of the diffuser 17 for a shallow angle of rotation (as shown in FIG. 7a). The steep angle of rotation is greater than the shallow angle of rotation of the primary vanes relative to the face 17a of the diffuser 17. In one form, the steep angle of rotation is a position whereby the primary vane 31 is at an angle of approximately 90° to the face 17a of the diffuser 17 and the shallow angle of rotation is a position whereby the primary vane 31 is at an angle of approximately 70° to the face 17a of the diffuser 17.

[0100] The airflow rate of the supply air stream 15 discharged by the swirl diffuser 17, for a constant total supply air pressure, is variable in a second range of rotation of the primary vanes 31. The airflow direction of the first air stream discharged by the diffuser is substantially parallel A to the face 17a of the diffuser 17 in the second range of rotation of the primary vanes 31. For the second range of rotation, the airflow rate of the supply air stream 15 discharged by the diffuser 17 varies between a substantially maximum airflow rate at a steep angle of rotation (as shown in FIG. 7a) and a substantially minimum airflow rate at a shallow angle of rotation (as shown in FIG. 7d). Again, the steep angle of rotation is greater than the shallow angle of rotation of the primary vane 31 relative to the face 17a of the diffuser 17. In one form, the steep angle of rotation is a position whereby that primary vane 31 is at an angle of approximately 70° to the face 17a of the diffuser 17 and the shallow angle of rotation is a position whereby the primary vane 31 is at an angle of approximately 0° to the face 17a of the diffuser 17. The angle between the primary vane 31 and the face 17a of the diffuser in the first range is greater than the angle between the primary vane 31 and the face 17a of the diffuser in the second range (i.e. an angle from within the range 70° to 90° is greater than an angle from within the range 0° to 70°). The angles between the primary vane 31 and the face 17a of the diffuser in the first and second ranges can be dependent on the total pressure of supply air stream 15 and/or the dimensions of the diffuser. For example, in an alternative embodiment, the first range can be approximately 80° to 90° and the second range can be 10° to approximately 80°. In another alternative embodiment, the first range can be approximately 60° to 80° and the second range can be 0 to approximately 60°.

[0101] In one form, the primary vanes 31 are not planar but twisted, whereby the central portion of each primary vane 31 has a steeper angle than one or both ends of the primary vane 31 relative to the face 27 of the diffuser 17, as shown in FIG. 15. This allows for the maximum primary vane 31 angle in the second range of rotation to be increased so as to increase the maximum amount of primary air 31 that may be discharged.

[0102] The first range of rotation is employed when the supply air stream's 15 temperature is warmer than the air in the space 19. In the first range of rotation, warm air can be directed downward from the face of the diffuser such that the throw, to an acceptably low terminal velocity, is approximately equal to the distance between the floor of the space and the diffuser face 17a. This is regulated by a combination of primary vane 31 angle in the first range of adjustment, airflow rate adjustment and supply-to-space temperature differential adjustment of the supply air stream. This arrangement overcomes the buoyancy of the warm supply air over the full heating range. The second range of rotation is employed when the supply air stream 15 is cooler than the air in the space 19. This allows for the diffusers to supply air to a large volume of space 19, which subsequently means that they can be spaced long distances apart. In one embodiment, basket droppers 1 can be placed up to 50 metres apart and supply air up to 8,000 litres/second, with each basket dropper can producing approximately 200 kW of capacity.

[0103] Referring again to FIGS. 7a-d, the swirl diffuser 17 will be described in further detail. The swirl diffuser 17 further comprises at least one secondary vane 33. The secondary vanes 33 are arranged to discharge a secondary airstream 35 such that it generally flows from the diffuser 17 in a plane that is substantially parallel to the face 17a of the diffuser 17. The primary vanes are arranged to discharge a primary airstream 37 that is induced downstream of the face of the diffuser by the secondary airstream 35 such that the direction of the primary airstream 37 is substantially determined by the direction of travel of the secondary airstream 35.

[0104] Rotation of the primary vanes 31 is able to vary the airflow rates of the secondary airstream 35 and of the primary airstream 37. Further, the primary vane 31 is able to vary the airflow rates of the primary airstream 37 and of the secondary airstream 35 substantially independently of one another. Rotation of the primary vanes 31 in a portion of the second range of rotation is able to reduce the airflow rate of the primary airstream 37 without substantially changing the airflow rate of the secondary airstream 35 (see for example, rotation between the positions shown in FIG. 7a and FIG. 7c). Rotation of the primary vanes 31 within a portion of the first range of rotation is able to reduce the airflow rate of the secondary airstream 35 without substantially changing the airflow rate of the primary airstream 37 (see for example, rotation between the positions shown in FIG. 7a and FIG. 7b)

[0105] In an embodiment shown in FIG. 16, the angle of rotation of all of the primary vanes 31 is substantially equal. When viewed along the longitudinal axis D, the predominant airflow pattern discharged by the swirl diffuser 17 covers an arc of 360°. In another embodiment shown in FIG. 17, the angle of rotation of some of the primary vanes, repeating in a regular pattern about longitudinal axis D (e.g. three out of every four, as shown) is substantially equal to one another and greater than the angle of rotation of the remaining primary vanes 31a, which are also repeating in a regular pattern about longitudinal axis D and are shown at the minimum angle. Again, the predominant airflow pattern discharged by the swirl diffuser 17 covers an arc of 360°, but over an airflow rate range that is smaller than that of the diffuser shown in FIG. 16, assuming that both operate at the same pressure. In the embodiment shown in FIG. 17, discharge components 39 could be permanently closed to reduce the capacity of the diffuser. For example, if every fourth diffuser component is not connected to the rotating element 73, the duty of the diffuser may be reduced by a quarter. This allows for a single basket dropper 1 to be used for a variety of different airflow rate ranges, and hence for different cooling or heating capacity requirements, without resizing the entire basket dropper.

[0106] In an embodiment detailed in FIG. 18, at least one of the primary vanes 31a is fixed at a shallow angle of rotation in the second range of rotation (for example, the position shown in FIG. 7d) while the other primary vanes 31 remain rotatable (i.e. are able to rotate from the position shown in FIG. 7b to the position shown in FIG. 7d) such that, when viewed along the longitudinal axis, the predominant airflow pattern discharged by the swirl diffuser covers an arc of less than 360°. This arrangement is useful when the basket dropper 1 is positioned near a wall or a fragile air curtain of a refrigeration unit in a supermarket. In this embodiment, at least one removable blocking element can also be installed in the diffuser 17 such that it substantially blocks the air path to fixed primary vane 31 to further reduce the airflow discharged by that fixed primary vane 31 if required (eg if the primary vane is twisted rather than planar).

[0107] It will be apparent to a person skilled in the art that many combinations of the principles described above with reference to FIG. 17 and FIG. 18 are possible, allowing for a single VAV diffuser to be used for multiple of airflow ranges, discharge pattern requirements and applications, thereby allowing for standardisation of the product range.

[0108] Advantageously, the swirl diffuser 17 depicted in FIGS. 16 to 18 includes a central hub, which may be removable to provide access to for replacement of the swirl diffuser electric actuator, and that may be used to locate sensors in communication with the space 19, such as temperature and CO.sub.2 sensors, which, due to the highly inductive discharge characteristics of the swirl diffuser depicted, even when discharging diagonally downwards, will, for a wide range of operating conditions, provide temperature and indoor air quality measurements that are substantially representative of the air conditions lower down in the space 19.

[0109] Referring now to FIGS. 8 to 12, the diffuser 17 will be described in further detail. The diffuser 17 includes a plurality of discharge components 39. In the detailed embodiment, the discharge components 39 have one secondary vane 33 and one primary vane 31. In alternative embodiments, a single discharge component could however include a plurality of primary and/or secondary vanes. As is shown in FIGS. 11 and 12, the discharge components 39 are located adjacent one another and about the central axis C to form the swirl diffuser 17. The discharge components 39 each include opposing peripheral support structures 41, 43 for supporting the primary vane 31 and the secondary vane 33. The primary and secondary vanes are located between the peripheral support structures 41, 43.

[0110] In the detailed embodiment, a secondary vane 33 is integrally formed with the opposing peripheral support structures 41, 43 to form a first portion of the discharge component, in the form of a moulded portion 45. The moulded portion 45 of the discharge component 39 is injection moulded from plastic. This method of forming the moulded portion 45 of the discharge component reduces the complexity and cost associated with forming a large swirl diffuser. Each moulded portion of the discharge component 39 can be injection moulded separately, saving on both cost and time, particularly where the size of the diffuser is large. For example, the diffuser shown in the detailed embodiments may be 2 metres in diameter and therefore is able to discharge up to 8,000 L/s of supply air. Manufacturing a diffuser of this size and complexity using traditional methods would be expensive and time consuming.

[0111] A primary vane 31 is rotatably mounted to the moulded portion 45 of the discharge component 39. The primary vane 31 includes connectors 47 that project from an inner surface 49 of the primary vane 31. The connectors 47 are adapted to connect to and be received by the moulded portion 45 of the discharge component 39 such that the primary vane 31 is able to rotate relative to the moulded portion 45 of the discharge component 39. The moulded portion 45 includes slots 51 that allow for the connectors 47 to be received by the moulded portion 45 during rotation of the primary vane 31. The primary vane 31 can be formed from plastic or metal, with the former offering the advantage of reduced on-going manufacturing cost and complexity of the diffuser, as well as affording the ability to snap-fit the primary vane 31 into the moulded portion 45, thereby allowing for quick and cheap assembly of the diffuser.

[0112] The opposing peripheral support structures 41, 43 include a proximal support structure 43 that is located adjacent to a centre (indicated by axis C in the Figures) of the swirl diffuser 17, and a distal support structure 41 that is located adjacent to the periphery of the swirl diffuser 17.

[0113] The distal support structure 41 of each moulded portion 45 comprises a recess 53 formed therein for supporting the distal support structure 41 of an adjacent discharge component 39. The distal support structure 41 of each discharge component also includes an arm 55 that projects from the secondary vane 33 and away from the recess 53. The arm 55 is able to be received by the recess 53 of another adjacent discharge component 39. In this way, multiple discharge components 39 can be located and aligned to hook into one another in a circular arrangement to form a swirl diffuser 17. The arm can sit in loose in the recess, so as to align the discharge components. Alternatively, the connection between the arm and the recess can be by interference or friction fit, adhesive fit, or plastic welding.

[0114] The distal support structure 41 of each discharge component 39 includes a first lip 57 projecting from an external wall 59 of the distal support structure 41, as well as a first and a second clip. The external wall 59 faces away from the centre of the diffuser 17. The proximal support structure 43 of each discharge component 39 includes a second lip 69 projecting from an external wall 71. The external wall 71 faces towards the centre of the diffuser 17, such that the second lip 69 opposes the first lip 57. The first and second lips 57, 69 are able to receive and abut to the underside of a plate 61 that forms both the face of the swirl diffuser, as well as the opposing lower end 11 of the basket dropper 1. The plate can be any shape to suit the application. The plate 61 includes a plurality of apertures 63 that are each configured to support one discharge component 39. The plurality of apertures 63 are spaced evenly around the central axis C, each aperture being bounded by an inset edge 67 that lies on a first circle centred at the central axis, an outer edge 65 that lies on a second larger concentric circle and sides of each aperture that lie on angularly spaced radii extending from the central axis C. The outer 65 and inset 67 edges that are located at opposing ends of each aperture 63. The edges 65, 67 are configured to connect to the discharge components 39 by abutting the upper edges of the first and second lips 57, 69, respectively. The outer edge 65 is located near the periphery of the diffuser 17 and the inset edge 67 is located near the centre of the diffuser 17 when assembled. The second lip 69 is adapted to receive the inset edge 67 of the plate 61 and the first lip 57 is adapted to receive the outer edge 65 of the plate 61 such that the discharge component 39 is able to be mounted within the aperture 63 of the plate 61. Therefore, each discharge component 39 can be slotted into an aperture 63 in the plate and a recess 53 of an adjacent discharge component 39.

[0115] The external walls 59, 71 of the proximal 43 and distal 41 support structures each comprise a locking tab, in the form of clips 73. The clips 73 projecting in opposing directions from the external walls 59, 71 (i.e. project away from the external wall 59, 71) of the proximal 43 and distal 41 support structures such that the outer 65 and inset 67 opposing edges of the plate 61 are able to be received between the lip 57, 69 and the clip 73 of each support structure 41, 43, thereby locking the diffuser component 39 to the plate 61. Each diffuser component 39 can therefore be clipped into and then supported by the plate 61 that forms face of swirl diffuser 17, as well as the lower end 11 of the basket dropper 1.

[0116] Referring again to FIG. 11, the diffuser 17 and the mechanism used to rotate the primary vanes 31 is described in detail. A rotating element 73 is located within the interior chamber of the duct 3 and is configured to rotate the primary vanes 31. The rotating element 73 includes a plurality of spokes 75 that radiate about the central axis C. As shown in FIG. 8, the primary vanes 31 include a rotator 77 that projects from the inner surface 49 of the primary vane 31. The rotator 77 of each primary vane 31 is configured to cooperate with the rotating element 73 to rotate the primary vane 31. The rotator 77 includes an aperture, in the form of guide slot 79, which has an arced profile. The guide slot 79 is able to receive a spoke 75 of the rotating element 73 such that rotation of the rotating element 73 rotates the primary vane 31. Alternative mechanisms are also possible. For example, the plurality of spokes 75 could be connected to the plurality of primary vanes 31 by means of linkages. In another alternate embodiment, rather than including a plurality of spokes 75, the rotation element 73 may include a circumferential crown gear that, for each discharge component 39, engages with a vane bevel gear that is in communication with primary vane 31. This particular embodiment will be described in further detail with reference to FIGS. 20 to 23.

[0117] Referring now to FIG. 19, an embodiment of the primary vane 31 will now be described. The primary vane 31 includes a substantially planar surface, in the form of flat surface 81, and an angled trailing edge lip 83. The angled trailing edge lip 83 is located adjacent to the diffuser face 17, downstream of the flat surface 81. The surface of the angled trailing edge lip 83 forms an obtuse angle with the flat surface 81 of the primary vane 81. In other words, in profile, the primary vane 31 includes a flat surface 81 and an angled lip 83 along its trailing edge, such that when the primary vane 31 is closed, the angled lip 83 is orientated at a greater angle to the face 17 of the diffuser relative to the angle between the flat surface 81 and the face 17 of the diffuser.

[0118] The method of constructing such a swirl diffuser includes the steps of moulding a plurality of discharge components 39, mounting a rotatable primary vane 31 to the discharge components 39 and then inserting the discharge components 39 into apertures 67 disposed within the plate 61. The discharge components 39 will then be supported by the plate 61 and the diffuser will be capable of discharging a swirling airflow.

[0119] An embodiment of the diffuser will now be described in further detail with reference to FIGS. 20 to 23. FIG. 20 shows an isometric view taken from the underside of the diffuser. In this form, the primary vanes 31 and secondary vanes 33 are recessed and directly fixed within a bellmouth discharge face 76. The bellmouth discharge face replaces the plate 61 detailed in the previously described embodiment. The use of a bellmouth discharge face allows the angle of the primary vanes 31 relative to the plane of the diffuser face to be increased relative to the previously described embodiment (i.e. including a flat discharge face) whilst achieving discharge substantially parallel to the plane of the diffuser face, thereby increasing the amount of air discharged relative to that achieved with a flat plate face when the discharge direction from the diffuser is substantially parallel to the plane of the diffuser face. A primary vane angle of 50° or more relative to the plane of the diffuser face can be achieved with the bellmouth whilst maintaining discharge substantially parallel to the plane of the diffuser face. FIG. 21 shows an isometric view from above of the alternative embodiment of the diffuser shown in FIG. 20. Again, the primary vanes 31 and secondary vanes 33 are recessed in the bellmouth discharge face. The primary and secondary vanes are therefore recessed both from the diffuser face and from within the throat of the diffuser.

[0120] Referring now to FIGS. 22 and 23, the mechanism used to actuate the primary vanes 31 is described in detail. A rotating element, in the form of crown gear 78, is located within the interior housing of the diffuser 76 and is configured to rotate about the central axis C to thereby actuate the primary vanes 31. Not shown in the Figures, for simplicity, is an actuator to drive the crown gear 78. The actuator may be located above the crown gear with a drive shaft centrally located and coincident with the diffuser central axis. The drive shaft can engage directly with the crown gear, which is also centrally located. The gear ratio may be such that the actuator drive shaft (and hence the crown gear that the drive shaft connects directly to) would rotate through 90° in order to drive the plurality of primary vanes from the fully closed position to the fully open position. This means that a standard rotary damper actuator, as used throughout the HVAC industry and typically available with 0-10V AI (analogue input for modulating control) and 24 V AC or 24 V DC power supply, can be used. Using a readily available actuator allows not only for simple sourcing and for controls and power requirements that are standard in the HVAC industry, but also for simple actuator replacement in the event of actuator failure. The actuator can be attached to a mounting frame, which would span the diameter of the diffuser neck, to be connected to the neck via rivets or similar.

[0121] FIG. 23 shows the connection between the vanes 31 and the crown gear 78. The crown gear includes projecting teeth 82 that are configured to mesh with corresponding teeth 86 of a plurality of bevel gears 84. Each bevel gear 84 is attached to a respective primary vane 31 such that rotation of the crown gear 78 about axis C causes a rotation of the primary vanes 31 about an axis that is substantially perpendicular to axis C. It will be apparent to a person skilled in the art that the disclosed arrangement can be reconfigured to include some of the primary vanes that are in a fixed open or fixed closed position (i.e. by reconfiguring the crown gear to drive some of the primary vanes or by omitting one or more bevel gears for the fixed primary vanes).

[0122] In the previously described embodiment, for each primary vane, a rotator connected to the primary vane engages with a spoke that rotates about the diffuser central axis to rotate the primary vane. The advantages of the alternative embodiment, whereby the crown gear engages a plurality of bevel gears, each of which is attached to a primary vane, thereby rotating the plurality of primary vanes, include the prevention of linkages (spokes, rotators, etc) from projecting into the air stream, thereby reducing noise and pressure drop, and also avoiding the risk of interference between linkage components and other diffuser components (in particular the secondary vane) during operation of the mechanism.

[0123] Returning to FIGS. 1, 2 and 4, the basket dropper 1 will be described in further detail. The upper end 7 of the duct 3 is profiled to fit within an aperture in an upstand 23a of a roof 23. As previously described, the upper end 7 has a mounting flange 21 that rests on the upstand 23a of the roof A gasket seal is located between the upper end 7 of the duct 3 and the air conditioning unit 9. Referring now to FIGS. 13 and 14, the connection between the roof, basket dropper and packaged air conditioning (PAC) unit will be described in further detail. In these detailed embodiments, there is no platform above the roof. The PAC 9 has a base frame 93 that surrounds the perimeter of the PAC 9, protruding beyond and hanging over the mounting flange 21, rather like a short skirt. The mounting flange 21 is not attached to the frame 93. Instead, the mounting flange 21 rests on the roof upstand 23a, transferring the weight of the basket dropper 1 onto the upstand 23a. Additionally, the weight of the air handler end of the PAC 9 is borne by the mounting flange 21, which transfers it to the upstand 23a. This is because the flat bottom underside of the PAC 9 (which is slightly higher than the surrounding PAC frame) rests on a gasket 95 sandwiched between the mounting flange 21 and the flat bottom of the PAC 9. The flat bottom underside of the PAC 9 provides both a flat surface for gasket 95 to seal to and lateral tolerancing of the PAC 9 on the gasket. In the detailed embodiment of FIG. 13, the flange 21 doubles up as over-flashing for the roof, which includes under-flashing 97, support beams 87 and sheeting 89. In this embodiment, the flange 21 not only protrudes outwards, but then folds downwards, so as to automatically form the over-flashing over the under-flashing 97 that is taken up the sides of the upstand 23a, thereby automatically weatherproofing the installed dropper installation. In the detailed embodiment of FIG. 14, the frame 93 doubles up as over-flashing for the roof, which includes under-flashing 97, support beams 87 and sheeting 89. In this embodiment, the under-flashing 97 is taken over the flange 21 and under the gasket 95, and the frame 93 hangs over over-flashing 97, to complete the weatherproofing. The PAC unit 9 can be lowered by crane to rest on the gasket 95 attached to the top end of the basket dropper 1. The module flange 21, therefore, supports both the basket dropper 1 and the air handling end of the PAC unit 9, thereby eliminating the need for a rooftop platform to support the PAC unit, and the gasket 95 creates an air tight seal for both the supply and return air ducts; it also provides tolerancing in the horizontal plane, so that a minor misalignment of the PAC unit 9, when it is landed onto the basket dropper 1, does not matter.

[0124] Referring now to FIGS. 13 and 14, the connection between the diffuser module and the roof will be described in detail. The upper end 7 is able to attach to gasket 95 and provide support for one end of the unit 9. Advantageously, in this embodiment, no rooftop platform is required to support the end of the unit supported by the upper end 7. In another alternative embodiment not detailed in the drawings, the upper end 7 of the duct 3 is profiled to fit within an aperture in a wall. In this alternative embodiment, the upper end 7 has a mounting flange that facilitates attachment of the basket dropper 1 to a support structure of the wall. In another alternative embodiment, the basket dropper 1 includes additional air outlets 85 (see FIG. 6), openings or perforations about the periphery of the duct 3 through which a part of supply air 15 is discharged. The discharge of a portion of supply air 15 through outlets such as nozzles may increase the horizontal throw of the supply air 15. The discharge of a portion of supply air 15 through perforations about the periphery adjacent to swirl diffuser 17 may reduce the induction of high level heat into the supply air stream 15 discharged by swirl diffuser 17, thereby improving energy efficiency when cooling. In a further embodiment, the basket dropper includes a fire sprinkler pipe internally and a sprinkler head protruding through the diffuser 17. In a further embodiment, the basket dropper includes wiring to a temperature sensor and a CO.sub.2 sensor, both of which may be located in the return air plenum 25 or beneath the centre of the diffuser 17, as well as wiring to an electric actuator of diffuser 17, as well as pressure piping to space 19 and to supply air plenum 3, especially to downstream of perforated baffle plate 13a.

[0125] The method of installing the described heating, ventilation and air conditioning (HVAC) system in/on the roof/wall of a building includes the steps of fabricating supporting framework protruding as a flange from duct 3, lowering or positioning a basket dropper 1 through the hole in the roof or wall until the protruding flange rests on the roof structure surrounding the hole, securing heating and cooling plant (unit 9) outside the roof or wall to the framework such that it rests on the diffuser module. This method of installing an HVAC system is extremely quick and, if required, does not require access to the internal structure of the building. The disclosed method therefore provides significant time savings associated with the installation of, particularly, HVAC systems for large open plan commercial spaces (e.g. a warehouse).

[0126] In the claims that follow and in the preceding summary except where the context requires otherwise due to express language or necessary implication, the word “comprising” is used in the sense of “including”, that is, the features as above may be associated with further features in various embodiments.

[0127] Variations and modifications may be made to the parts previously described without departing from the spirit or ambit of the disclosure.