GB2189023A - Mounting a ventilator fan in a wall - Google Patents

Abstract

An extractor fan is provided with a pipe 17 to facilitate the mounting of the fan upon a wall 16. The pipe 17 is inserted into, and embedded within, an aperture formed in the wall 16 and component parts of the extractor fan are then mounted on the ends of the pipe by screws which pass into apertures formed in the end of the pipe. The pipe 17 may be formed either as a single component or as a multi-component pipe. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a method of and apparatus for wall mounting a fan The present invention relates to a method of and apparatus for wall mounting a fan, more particularly an electric extractor fan.

Whilst, in this specification, reference will be made to an extractor fan, it is to be appreciated that this term is to include fans used either to extract air from a space being ventilated or, alternatively, to inject air into the space being ventilated. Indeed certain embodiments of extractor fan presently available commercially are provided with reversible motors or impellers so that they can both extract air from and inject air to a space being ventilated.

Many types of extractor fan assembly have been proposed previously, most of which have been intended for mounting in position on a window. Such fans usually comprise two housing elements, one element being mounted on one side of the window, and the other element being mounted on the other side of the window, the two elements being connected in some way through a hole formed in the glass of the window. It is, however, sometimes desirable to mount an extractor fan in a wall of a building, for example, in rooms where it may not be practicable to provide a window but where a throughflow of air is desirable.

The normal procedure presently adopted for mounting an extractor fan in a wall comprises the initial step of forming an aperture in the wall corresponding approximately to the size of the fan. A common problem is that it is difficult to provide an aperture of precisely the required shape and size in a wall of conventional construction. If the wall is a brick wall, for example, complete bricks at the periphery of the aperture may be dislodged, thus providing an aperture with a very irregular periphery.

If the size of the aperture formed does not correspond fairly closely to the dimensions of the fan to be mounted in the wall then it is necessary to finish the aperture to the required size by filling in parts of the aperture with cement or some other suitable filler.

Particular problems occur when attempting to mount an extractor fan in a cavity wall, i.e.

a wall comprising an inner wall and an outer wall separated by a gap or cavity. If an extractor fan is simply mounted over the ends of an aperture formed through a cavity wall then the air extracted from the space being ventilated tends to flow into the cavity between the two wall surfaces and may flow around the walls of the building in the cavity.

In an attempt to overcome the problems encountered when mounting an extractor fan on a cavity wall it has been proposed to provide a pipe within the aperture formed within the cavity wall, the pipe being cemented in place within the aperture. Then, when the fan is mounted in position the air extracted by the fan passes through the pipe to the outside of the building and does not enter the cavity. It will thus be appreciated that after the aperture in the wall has been prepared the periphery of the aperture through the wall will most probably be surrounded by wet cement or other filler.

The next step in mounting the fan in position is to provide screw holes adjacent the aperture to receive screws used to hold the two housing elements of the fan on the two opposite sides of the wall. Since it is not practicable to provide screw holes in such wet cement or filler it is necessary to wait until the cement or filler has hardened or dried.

This may make it necessary for the person fitting the fan to make two visits to the site, thus significantly increasing the cost of fitting the fan.

According to one aspect of this invention there is provided a method of mounting an extractor fan upon a wall, said method comprising the steps of forming an aperture in said wall, inserting a pipe into said aperture, said pipe being an elongate, hollow member having a longitudinal axis, said method comprising the further steps of firmly embedding the pipe in position within the wall by filling the gap between the pipe and the aperture with a suitable filler and mounting the component elements of the extractor fan on opposite ends of the pipe so that the component elements of the fan are connected to and supported by the pipe.

According to another aspect of this invention, there is provided a method of mounting an extractor fan upon a wall, said method comprising the steps of forming an aperture in said wall, inserting a pipe into said aperture, said pipe being an elongate, hollow member having a longitudinal axis and comprising means disposed at opposed ends thereof defining apertures for receiving screws, said method comprising the further steps of firmly embedding the pipe in position within the wall by filling the gap between the pipe and the aperture with a suitable filler and mounting component elements of the extractor fan on opposite ends of the pipe by passing screws through the component elements of the fan and screwing the screws into the said screw receiving apertures in a direction substantially parallel to the longitudinal axis of the pipe, so that the component elements of the fan are connected to and supported by the pipe.

Preferably, said means defining said apertures are formed integrally with said pipe.

Conveniently, said means define two said apertures at each end of said pipe.

Advantageously, said pipe is of circular cross-section and said means defining said apertures comprises a plurality of longitudinally extending, diametrally opposed lips formed on the outer periphery of said pipe.

Preferably, said lips define substantially keyhole-shaped channels extending axially of the pipe, said keyhole-shaped channels being open at their radially outermost ends, the axial ends of the channels constituting said apertures for receiving said screws.

Conveniently, said lips extend over the entire length of said pipe.

Preferably, said pipe is formed of a plastics material, and may be formed as an extruded member.

Alternatively said pipe may be formed from a plurality of interconnectable components, the components being interconnected by a projection on one component and a correspondingly shaped recess on the adjacent component.

Conveniently each component is an elongate component of arcuate cross-section, which is provided upon its radially outer surface with a longitudinally extending pair of lips which define an elongate channel, the ends of which constitute said means defining said apertures.

Preferably four said components are required to form said pipe, said four components being substantially identical and each component constituting one quarter of the periphery of said pipe.

Advantageously a radially outer surface of each said component is provided with a plurality of longitudinally extending parallel ribs.

According to another aspect of this invention there is provided an extractor fan, when mounted on a wall, said extractor fan comprising two or more component elements, at least one on each side of the wall, the component elements being connected to and supported by a pipe embedded in an aperture formed in the wall.

Preferably, said pipe comprises means at the opposed ends thereof defining apertures for receiving screws, the component elements of the fan being connected to the pipe by means of screws passing into said apertures in a direction substantially parallel to the longitudinal axis of the pipe The pipe may be formed from a plurality of interconnectable components.

According to a further aspect of invention there is provided a pipe, said pipe being an elongate, hollow member having a longitudinal axis and comprising means disposed at opposed ends thereof defining apertures for receiving screws, the apertures being such that the screws may be inserted in to said apertures in a direction substantially parallel to said longitudinal axis with the screw thread on each screw threadedly engaging the aperture.

The pipe may be formed from a plurality of interconnectable components.

In order that the present invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a partial cross-section showing an extractor fan mounted on a cavity wall in accordance with the invention; Figure 2 is an exploded, partly cut-away, perspective view of part of the extractor fan of Fig. 1 as mounted on one side of the wall; Figure 3 is an exploded, partly cut-away, perspective view of another part of the extractor fan shown in Fig. 1 mounted on the other side of the wall; Figure 4 is an exploded, perspective view of an alternative extractor fan mounted on a cavity wall in an alternative manner, with part of the wall cut away for clarity of illustration; and Figure 5 is an end view of one component of the pipe on which extractor fan of Fig. 4 is mounted.

Referring to Fig. 1 an extractor fan 1 comprises an inner housing element 2 and an outer housing element 3. The inner housing element 2 is shown more clearly in Fig. 2, whilst the outer housing element 3 is shown more clearly in Fig. 3. Both the inner housing element 2 and the outer housing element 3 of the fan 1 are substantially rectangular in shape. When the fan is to be mounted on a window then the inner housing element 2 is mounted on the inside of the window, whilst the outer housing element 3 is mounted on the outside of the window.

The inner housing element 2 of the fan 1 is shown in Fig. 2 and comprises a substantially rectangular housing 4, within which is housed a fan 5 and an electric motor (not shown in the drawings). The housing 4 defines a central, circular aperture 6 within which the motor and fan 5 are located. The housing 4 is provided with two diametrically opposed bores 7, through which securing screws 8 may be inserted, in order to mount the inner housing element 2 in position. The inner housing element 2 is also provided with a removable grille 9 which may be mounted upon the side of the inner housing element 2 located innermost within the space to be ventilated.

The outer housing element 3, comprises a substantially rectangular housing 10 of the same general configuration as the housing 3 of the inner housing element 2 and also defines a central, circular aperture 11, through which air may flow. One side of the housing 10 is provided with a series of parallel, spaced-apart slats 12 (shown in part in the drawings). The purpose of the slats 12 is to prevent the penetration of rain and gusting winds into the fan assembly. The opposite side of the housing 10 is provided with a cylindrical projection or spigot (not visible in the drawings), which may pass through a window or into a pipe located within an aperture in a wall upon which the fan 1 is to be mounted.The spigot is usually provided with a seal or gasket which fits around the outer periphery of the spigot in order to form a seal with the inside of the pipe or with a pane of glass mounted in the window in which the fan is to be mounted. The central aperture 11 provided in the housing 10 of the outer housing element 3 incorporates diametrically opposed recesses 13 which are blocked off at one end so as to form partial flange portions 14. Each flange portion 14 is provided with a bore suitable for receiving screws 15 used to locate the outer housing element 3 of the fan 1 in position.

Provided for use with the fan 1 when the fan is intended to be mounted on a wall 16 of a building is a pipe 17. The pipe 17 is of circular cross-section and is in the form of an elongate, hollow member having a central, longitudial axis 18. The pipe 17 is formed from a plastics material and is manufactured by extrusion. Formed integrally with the pipe 17 are two diametrically opposed projections 19, the projections 19 extending longitudinally over the full length of the pipe 17. The projections 19 project radially outwardly from the outer periphery of the pipe 17 and are each provided with a keyhole-shaped channel 20.

The channels 20 each define, at each end of the pipe, a circular aperture 21 which corresponds to the head of the keyhole and a rectangular aperture 22 corresponding to the body of the keyhole. The circular aperture 21 corresponding to the head of the keyhole is positioned radially innermost in the projections 19, with the rectangular aperture 22 extending radially outwardly from the circular aperture 21. The rectangular aperture 22 is open at its radially outermost edge and it will therefore be appreciated that the projections 19 effectively comprise two slightly flexible lips 23.The pipe 17 is designed so that the circular aperture 21 at the ends of the keyhole-shaped channel 20 are aligned with the bores 7 in the inner housing element 2 and the corresponding bores in the outer housing element 3, so that the screws 8, 15 may be passed through the respective housing elements and screwed into the circular apertures 21 in order to locate the housing elements on the ends of the pipe 17. Thus the channels 20 effectively define means at the ends of the pipe adapted to receive mounting screws used to mount the housing elements of the fan in position. It will be appreciated that when the screws 8, 15 are passed through their respective housing elements they will then be inserted into the circular apertures 21 in a direction substantially parallel to the longitudinal axis 18 of the pipe 17.The flexibility of the lips 23 of the projections 19 allows various sizes of screws 8, 15 to be used to locate the housing elements 2, 3 in position on the ends of the pipe 17, since the lips 23 will merely expand or be forced apart if oversize screws are used. The extruded pipe 17 may have a length equal to or slightly less than the thickness of the wall 16.

In order to mount an extractor fan, as described above, on the wall of a building, it is first necessary to provide a hole or aperture 24 in the wall 16, with the size of the aperture 24 being greater than the size of the central, circular apertures 6, 11 provided in the inner and outer housing elements 2, 3 of the fan. The pipe 17 is then cut to length, if necessary, so that the length of the pipe is equal to or just less than the thickness of the wall 16. The pipe 17 is then inserted into the aperture 24 and firmly embedded in position using cement 25 or the like to fill any gaps between the pipe 17 and the aperture 24.

The inner housing element 2, optionally with an associated gasket, is then offered up to the end of the pipe 17 located on the inside of the wall 16 and the screws 8 are passed through the housing element 2 and screwed loosely into the circular apertures 21 of the channel 20. The outer housing element 3 is then offered up to the opposite end of the pipe 17, with the spigot being inserted into the pipe 17 so that the seal around the spigot forms a seal with the inner periphery of the pipe 17. With the outer housing element 3 held in position on the end of the pipe 17 the screws 15 can then be inserted through the bores in the flange portions 14 of the housing 10 of the housing element 3 and screwed loosely into the circular apertures 21 of the channel 20.The screws 8, 15 can then be tightened in order to firmly mount the inner housing element 2 and the outer housing element 3 of the fan 1 in position on the ends of the pipe, so that the elements of the fan are mounted on and supported by the pipe.

The pipe 17 may be relatively large, for example approximately 200 mm in diameter and 400 mm in length. This makes the packaging for the components of one fan assembly rather bulky and the packaged components require a considerable amount of storage space.

In order to overcome this inconvenience the pipe 17 may be formed as a multi-component pipe so that the components take up less space when disassembled than a complete pipe and therefore the amount of storage space per fan assembly is reduced.

Fig. 4 illustrates an arrangement in which the pipe 17 is formed from a plurality of substantially identical components 26. In this embodiment the inner and outer housing elements 2, 3 are respectively mounted on the pipe 17 via an inner and an outer mounting plate 27, 28.

In the specific design illustrated in Fig. 4 the pipe 17 is formed from four substantially iden tical components 26. One component 26 is illustrated in end view in Fig. 5. The component 26 is a thin, elongate component which may be formed from a plastics material by extrusion. The component 26 is of arcuate cross-section and is designed so as to form a quarter of the periphery of the circular pipe 17. Each component 26 is designed to interconnect with a further component 26 by way of a snap-fitting or slide fitting interconnection, such that four components form a complete pipe 17.

For the purpose of joining the components together each component 26 is provided along one longitudinal edge with a shaped, elongate projection 27 and along its other longitudinal edge with a correspondingly shaped recess 28. The projection 27 comprises a first portion 29 of substantially circular cross-section formed integrally along the edge of the component 26 and a second portion 30 formed on the side of the first portion 29 which is remote from the edge of the component 26, the second portion 30 being of substantially rectangular cross-section and having a rounded head along its free edge. The recess 28 is defined between a pair of arms 31 and comprises a substantially circular-section portion 32 adjacent the free ends of the arms 31 leading into a substantially rectangular portion 33 having a rounded inner end.

The underside or radially inner surface 34 of the component 26, which forms the internal surface of the assembled pipe 17, is a smooth surface, whilst the upper or radially outer surface 35, which forms the outer surface of the assembled pipe 17, is provided with a plurality of longitudinally extending, parallel ribs 36. The ribs 36 assist the setting of the pipe 17 in position when the pipe is cemented in an aperture within a wall.

A pair of lips 37 extend longitudinally along the radially outer surface 35 of the component 26 at a position centrally between, and in a direction parallel to, the two longitudinal edges of the component. The two lips 37 define a keyhole-shaped channel 38 comprising a tapering entrance 39 and a circular cross-sectioned base 40. The channel 38 is open ended and therefore presents an aperture at each end of the component 26 which is designed to receive screws by of which component parts of the fan 1 are mounted on the pipe 17. The lips 37 are slightly flexible and thus the apertures are capable of receiving screws of differing sizes.

It will be appreciated that with four identical components 26 forming the pipe 17 there will be four longitudinally extending channels 38 running along the pipe, offset at approximately 900 around its outer periphery. It would of course be possible to form the pipe 17 from two componets 26 and two further components which do not have a channel 38 so that the resulting pipe has two diametrically opposed channels 38 similar to the embodiment illustrated in Figs. 1 to 3.

With the arrangement illustrated in Fig. 4 the inner housing element 2 of the fan 1 is mounted on one end of the pipe 17 by way of an inner mounting plate 27 which is a substantially rectangular plate having a central circular aperture 41 and a pair of diametrically opposed arcuate slots 42 by way of which the plate is mounted on the pipe 17. The outer housing element 3 is mounted on the opposite end of the pipe 17 by way of on outer mounting plate 28 which again comprises a substantially rectangular plate 43 having a central circular aperture 44 and a pair of diametrically opposed arcuate slots 45 by way of which the plate is mounted on the pipe 17.

In addition the outer mounting plate 28 is provided on one side with an upstanding projection 46 surrounding the central circular aperture 44. The projection 46 is designed to be insertable into the assembled pipe 17.

In order to mount an extractor fan as illustrated in Fig. 4 upon the wall of a building, it is first necessary to provide a hole or aperture 24 in the wall 16. The size of the aperture 24 should be slightly larger than the central, circular apertures 41, 44 provided in the inner and outer mounting plates 27, 28. The components 26 can then be cut to length, if necessary, so that the length of each component is equal to or just less than the thickness of the wall 16. The pipe 17 is then assembled from the four components 26 by snap fitting the components together by way of the projections and corresponding recesses provided along each longitudinal edge thereof.

Thus the projection 27 of one component is inserted in the recess 28 of an adjacent component, thus forming a semi-circular assembly.

Two further components are added in a similar way to form a complete pipe.

The assembled pipe 17 is then inserted into the aperture 24 and firmly embedded in position using cement or the like to fill any gaps between the pipe 17 and the aperture 24.

The inner mounting plate 27 is then offered up to the end of the pipe 17 located on the inside of the wall 16 and is then secured onto the end of the pipe 17 by passing screws 47 through the arcuate slots 42 so that they are received in the apertures in the ends of two diametrically opposed channels 38. The arcuate configuration of the slots 42 allows for any misalignment of the mounting plate 27 with the end of the pipe 17. Once the mounting plate 27 is attached to the end of the pipe 17 the inner housing element 2 may be mounted upon the mounting plate 27 by way of the screws 8 passing through the housing element and being screwed into bosses 49 on the mounting plate 27.

The outer mounting plate 28 is then offerred up to the opposite end of the pipe 17 with the upstanding projection 46 being inserted into the pipe 17 so that the mounting plate 28 forms a seal around the end of the pipe 17. The outer mounting plate 28 is then screwed into place on the end of the pipes 17 by screws 48 through the arcuate slots 45 and into the apertures at the ends of two diametrically opposed channels 38. Once the outer mounting plate 28 is mounted in position on the end of the pipe 17 the outer housing element 3 may be mounted upon the mounting plate by way of further screws passing through the housing element 3 and into bosses on the plate 28. The mounting plates 27, 28 cover the cement adjacent the ends of the pipe 17 and prevent any flaking cement from entering either of the housing elements 2, 3 within which the fan components are housed.

As an alternative to providing a multi-component pipe 17, packaging and storage space may be saved by using a pipe which is initially a substantially planar member formed from a flexible material. The planar member may be provided with longitudinally extending lips which define a channel whose ends present apertures for receiving screws, similar to the lips 37 and channel 38 illustred in Fig. 5. The member may be formed integrally on opposed edges with interconnecting means so that the member can be folded over on itself to form a substantially circular pipe. Alternatively a separate clamping arrangement may be provided so that the member is folded over on itself to form a circular pipe, with the adjacent free edges of the pipe then being clamped together by suitable clamping means.

It will be appreciated from the above description that the mounting of a fan 1 upon a wall 16 may be completed in one simple set of operations. Since the two housing elements 2, 3 of the fan 1 are screwed to the pipe 17 it is not necessary to wait for the cement 25 to dry. Thus the fan can be fitted in only one visit to the site.

It will be appreciated that many modifications and variations may be made to the disclosed fan assembly without departing from the scope of the present invention. For example, precise details of the inner and outer housing elements of the fan have not been given since many alternative embodiments of fan may be used with the present invention.

The pipe 17 may also be modified such that the projections 19 or lips 37 do not extend along the entire length of the pipe 17, but instead are only present at the ends of the pipe. The pipe 17 need not necessarily be formed from four components as described in the specific embodiment, but can be formed from any convenient number of interconnectable components.

Claims (38)

1. A method of mounting an extractor fan upon a wall, said method comprising the steps of forming an aperture in said wall, inserting a pipe into said aperture, said pipe being an elongate, hollow member having a longitudinal axis, said method comprising the further steps of firmly embedding the pipe in position within the wall by filling the gap between the pipe and the aperture with a suitable filler and mounting the component elements of the extractor fan on opposite ends of the pipe so that the component elements of the fan are connected to and supported by the pipe.

2. A method of mounting an extractor fan upon a wall, said method comprising the steps of forming an aperture in said wall, inserting a pipe into said aperture, said pipe being an elongate, hollow member having a longitudinal axis and comprising means disposed at opposed ends thereof defining apertures for receiving screws, said method comprising the further steps of firmly embedding the pipe in position within the wall by filling the gap between the pipe and the aperture with a suitable filler and mounting component elements of the extractor fan on opposite ends of the pipe by passing screws through the component elements of the fan and screwing the screws into the said screw receiving apertures in a direction substantially parallel to the longitudinal axis of the pipe, so that the component elements of the fan are connected to and supported by the pipe.

3. A method according to Claim 2, wherein said means defining said apertures are formed integrally with said pipe.

4. A method according to Claim 2 or Claim 3, wherein said means define two said apertures at each end of said pipe.

5. A method according to any one of Claims 2 to 4, wherein said pipe is of circular cross-section and said means defining said apertures comprises a plurality of longitudinally extending, diametrally opposed lips formed on the outer periphery of said pipe.

6. A method according to Claim 5, wherein said lips define substantially keyhole-shaped channels extending axially of the pipe, said keyhole-shaped channels being open at their radially outermost ends, the axial ends of the channels constituting said apertures for receiving said screws.

7. A method according to Claim 5 or Claim 6, wherein said lips extend over the entire length of said pipe.

8. A method according to any one of Claims 1 to 7, wherein said pipe is formed of a plastics material.

9. A method according to any one of Claims 1 to 8, wherein said pipe is formed as an extruded member.

10. A method according to any one of Claims 1 to 8, wherein said pipe is formed from a plurality of interconnectable components.

11. A method according to Claim 10, wherein the components are interconnected by a projection on one component and a correspondingly shaped recess on the adjacent component.

12. A method according to Claim 11, wherein each component is an elongate component of arcuate cross-section, each component being provided upon its radially outer surface with a longitudinally extending pair of lips which define an elongate channel, the ends of which constitute said means defining said apertures.

13. A method according to any one of Claims 10 to 12, wherein four said components are required to form said pipe.

14. A method according to Claim 13, wherein said four components are substantially identical, each component constituting one quarter of the periphery of said pipe.

15. A method according to any one of Claims 10 to 14, wherein a radially outer surface of each said component is provided with a plurality of longitudinally extending parallel ribs.

16. An extractor fan, when mounted on a wall, said extractor fan comprising two or more component elements, at least one on each side of the wall, the component elements being connected to and supported by a pipe embedded in an aperture formed in the wall.

17. An extractor fan according to Claim 16, wherein said pipe comprises means at the opposed ends thereof defining apertures for receiving screws, the component elements of the fan being connected to the pipe by means of screws passing into said apertures in a direction substantially parallel to the longitudinal axis of the pipe.

18. An extractor fan according to Claim 16 or 17, wherein said pipe is of circular crosssection and said means defining said apertures comprises a plurality of longitudinally extending diametrally opposed lips formed on the outer periphery of the pipe.

19. An extractor fan according to any one of Claims 16 to 18, wherein said pipe is formed from a plurality of interconnectable components.

20. A pipe, suitable for use in the method of any one of Claims 2 to 15, said pipe being an elongate, hollow member having a longitudinal axis and comprising means disposed at opposed ends thereof defining apertures for receiving screws, the apertures being such that the screws may be inserted into said apertures in a direction substantially parallel to said longitudinal axis with the screw-thread on each screw threadedly engaging the aperture.

21. A pipe according to Claim 20, wherein said means defining said apertures are formed integrally with said pipe.

22. A pipe according to Claim 20 or 21, wherein said means define a plurality of said apertures at each end of said pipe.

23. A pipe according to any one of Claims 20 to 22, wherein said pipe is of circular cross-section and said means defining said apertures comprises a plurality of longitudinally extending, diametrally opposed lips formed on the outer periphery of said pipe.

24. A pipe according to Claim 23, wherein said lips define substantially keyhole-shaped channels extending axially of the pipe, said keyhole-shaped channels being open at their radially outermost ends, the axial ends of the channels constituting said apertures for receiving said screws.

25. A pipe according to Claim 23 or Claim 24, wherein said lips extend over the entire length of said pipe.

26. A pipe according to any one of Claims 20 to 25, wherein said pipe is formed of a plastics material.

27. A pipe according to any one of Claims 20 to 26, wherein said pipe is formed as an extruded member.

28. A pipe according to any one of Claims 20 to 27, wherein said pipe is formed from a plurality of interconnectable components.

29. A pipe according to Claim 28, wherein the components are interconnected by a projection on one component and a correspondingly shaped recess on the adjacent component.

30. A pipe according to Claim 29, wherein each component is an elongate component of arcuate cross-section, each component being provided upon its radially outer surface with a longitudinally extending pair of lips which define an elongate channel, the ends of which constitute said means defining said apertures.

31. A pipe according to any one of Claims 28 to 30, wherein four said components are required to form said pipe.

32. A pipe according to Claim 31, wherein said four components are substantially identical, each component constituting one quarter of the periphery of said pipe.

33. A pipe according to Claim 31, wherein the four components comprise two pairs of identical components, the components of one pair carrying a longitudinally extending pair of lips defining a channel, the ends of which constitute the means defining said apertures.

34. A pipe according to any one of Claims 28 to 33, wherein the outer surface of each said component is provided with a plurality of longitudinally extending parallel ribs.

35. A pipe substantially as herein described, with reference to, and as shown in, the accompanying drawings.

36. A method of mounting an extractor fan upon a wall substantially as herein described.

37. An extractor fan when mounted on a wall substantially as hereinbefore described, with reference to, and as shown in, the accompanying drawings.

38. Any novel feature or combination of features disclosed herein.