GB2045917A - Roof ventilators - Google Patents

Abstract

A louvred ventilator, especially for flat roof mounting, has pile sealing strips (106) carried adjacent the leading edges (44) of the louvres (40) at locations to project transversely across water drainage channels (57) formed between overlapping portions of the louvres when closed. Further pile sealing strips (100) on the ventilator casing seal against the side edges of the louvres. Seals (106) are favourably positioned not to obstruct the ventilation opening when the louvres are open. When the louvres are closed water may still drain under flanges (65) into channels (57) and thence under seals (100) to the outside of the ventilator. Thus, a drained, flat roof, louvred ventilator is provided which is substantially fully sealed when closed. <IMAGE>

Description

SPECIFICATION Improvements in ventilators This invention relates to ventilators and concerns louvred ventilators.

It is well known to provide a louvred ventilator having louvres hingeably movable to open and close the ventilator and control the ventilation therethrough. It is desirable that, in their open position, the louvres define air passages within a duct. Otherwise the exhaust of stale air through the ventilator cannot be assured under windy conditions but instead, a draught is created inwardly through the ventilator, into the building, when the ventilator is open.

With such a louvred ventilator, it is necessary for the louvres to prevent weather entry in their closed position.

In earlier prior art arrangements it was usual for the louvres to engage against one another and in many cases against a sealing flange or lip at the mouth of the duct to provide a weather tight seal.

However, where as is now quite often the case, a louvred ventilator is required to be roof mounted, on a flat roof for example, this type of weather sealing is not possible because water is unable to run off the ventilator but tends, instead, to seep between the interengaging surfaces and drip into the building.

Accordingly, it is now more common to construct a louvred ventilator in such a way that the louvres combine together when closed to form a water shield within the duct which shield acts to drain water over the sides of a ventilation opening formed at the upstream end of the duct and into gutters formed within the duct to the outside of walls defining the ventilation opening, which gutters lead water draining over the sides of the water shield out of the duct, onto the outside of the roof surface for example.In order to form the water shield, the louvres have leading and trailing edge portions respectively which overlap one another, the overlapping portions having respectively, upturned and downturned flanges which combine together to form water traps which lead water penetrating under the downturned, trailing edge flanges transversely over the side edges of the leading edge portions of the next adjacent louvres, into the gutters.

A louvred ventilator in which the louvres close to form a water shield in the ventilator duct is capable of fully weathering a ventilation opening even when the ventilator is mounted at a very shallow angle of inclination, and such ventilators are, therefore, quite often employed as clear opening fire ventilators, as well as natural, flat roof ventilators for that reason.

A problem which now arises is that by virtue of their design, which avoids the use of mutually engaging sealing surfaces, the prior art ventilators are not airtight when closed and because of this, there is a severe heat loss through the ventilators during winter-time. Also, in the case where the ventilators are mounted at a lower level, their lack of airtightness gives rise to draughts, and allows the penetration of dirt and dust.

Afurther problem is that the ventilators are not very good sound insulators when closed.

British Patent 355,448 describes a louvred ventilator for a vehicle roof in which the louvres have leading and trailing edge portions respectively which overlap one another, the overlapping portions having, respectively, upturned and downturned flanges which combine together to form water traps which lead water penetrating under the downturned trailing edge flanges transversely over the side edges of the leading edge portions of the next adjacent louvres into drainage gutters lying along two opposite sides of the roof opening. The upturned leading edge flanges each carry a rubber strip along, and gripping round, its upper edge to engage the underside of the next adjacent louvre to prevent rattling. The rubber strips serve simultaneously as stops and act also as seals. Because of their positioning, and their stop forming and anti-rattle function, the strips wear quite rapidly.Also, the strips become ineffective as seals if the louvres should become bent, or sag under their own weight. The rubber of the strips is subject to perishing due to atmospheric pollution. A further disadvantage is that the strips can become frozen to the adjacent louvres which prevents the ventilator from being opened or causing the strips to be damaged or torn off when the ventilator is forced open.

An object of the present invention is to provide an improved sealing arrangement between the adjacent louvres which avoids these disadvantages.

To this end, the present invention provides a louvred ventilator comprising a plurality of louvres hingeably movable to control ventilation through a ventilation opening of the ventilator, the louvres overlying and spanning an opposed pair of walls defining one pair of opposite sides of the opening to drain water on the outer surfaces of the louvres over said walls to the outside thereof, the louvres overlapping one another in their closed position to define a transverse water channel between an inner, leading edge portion of each louvre and an outer trailing edge portion of the next adjacent louvre and flexible sealing strips carried by the louvres and disposed longthwiseofthe louvres to engage between the overlapping portions of the louvres at locations spaced from the leading and trailing edges of the louvres.

Such sealing strips may be mechanically or adhesively secured to the louvres and are flexible enough to remain in sealing contact with the louvre surface against which they strike when the louvres are closed despite deflections of or irregularities in the louvre surfaces. The sealing strips still prevent the penetration of water between the louvres when the louvres are closed and dust is trapped in a satisfactory way due to the labyrinth path it must foliow to arrive at the seal. This labyrinth path also helps in increasing the sound insulation of the ventilator when closed. Also, since the sealing strips act bet ween the overlapping portions of the louvres they do not additionally block the ventilation opening when the louvres are open.Since the sealing strips engage between the louvre surfaces at locations spaced from the leading and trailing edges of the louvres the water channels remain open to drain water on the outer surfaces of the louvres to the outside of the ventilation opening. Also, the sealing strips are not exposed to the condensation of water droplets which might freeze to adhere the strips to their striking surfaces on the adjacent louvres so causing the strips to be damaged or torn off when the louvres are moved to their open positions.

Preferably, the sealing strips project across the water channels.

This ensures that the sealing strips are brushed substantially transversely by the louvre surfaces with which they strike during opening and closing movements of the louvres with the advantage that the sealing strips are not crushed between the louvres when the louvres are moved to their closed positions. This prevents the possible sticking of the sealing strips to the striking surfaces under pressure with consequent damage to the strips when the ventilator is opened. It also allows the ventilator to be controlled with relatively light operating gear since the opening gear will never be overstrained due to sticking.

Preferably also, the sealing strips are composed of or comprise a pile of woven yarn or natural or synthetic fibres which have been treated with a waterrepellent substance.

This ensures that under freezing conditions the sealing strips cannot become adhered to the striking surfaces due to icing of water seeping onto the sea I- ing strips from outside the ventilator, with consequent damage to the strips and/or the control gear when the ventilator is opened.

A further object of the present invention is to provide a louvred ventilator which is substantially airtight when closed and yet which is capable of weathering a flat roof ventilation opening without having to be disposed at a substantial angle of inclination in order to drain off water.

To this end, the present invention further provides a louvred ventilator comprising an outer body part or casing defining a duct, a ventilation opening defined within the duct between an opposed pair of walls of an inner body part or casing within the duct, a plurality of louvres hingeably movable to control ventilation through the ventilation opening, the louvres overlying and spanning said opposed pair of walls to drain water on the outer surfaces of the louvres over said walls into gutter means in said duct and leading outside said duct, the louvres overlapping one another in their closed position to define a transverse water channel between an inner leading edge portion of each louvre and an outer trailing edge portion of the next adjacent louvre, first flexible sealing strips positioned to engage between said outer body part and portions of the side edges of the louvres extending from their trailing edges, when the louvres are in their closed positions, and second flexible sealing strips carried by the louvres and disposed lengthwise of the louvres to engage between the overlapping portions of the louvres at locations spaced from the leading and trailing edges of the louvres, said transverse water channels opening at their two ends respectively over side edge portions of the louvres extending from their leading edges to communicate with the side of said first flexible sealing strips adjacent said gutter means.

With a ventilator in accordance with the present invention as defined in the immediately preceding paragraph, the flexible sealing strips render the ventilator substantially draught-proof, dust-proof and sound-proof, whilst at the same time, water may penetrate under the trailing edges of the louvres and be lead off by the transverse water channels and said gutter means and cannot, therefore, accumulate on the outer surfaces of the louvres even when the ventilator is mounted in a horizontal position. Such accumulation of water could lead to seepage of water past the sealing strips into the building and in freezing conditions to the complete icing-up of the ventilator, preventing it opening automatically in quick response to the onset of a fire condition.

Specific embodiments of the present invention will now be described by way of example, and not by way of limitation, with reference to the accompanying drawings in which: Fig. 1 is a side view of a portion of a ventilator in accordance with the present invention and showing overlapping trailing and leading edge portions of an adjacent pair of louvres of the ventilator and flexible sealing strips provided in accordance with the present invention, Fig. 2 is a cross-sectional side elevation of a further ventilator according to the present invention, with a central portion broken away, the louvres being shown in their closed position, Fig. 3 is a partial plan view of the ventilator shown in Fig. 2 with a central portion broken away, Fig. 4 is a side view corresponding with Fig. 2 and showing the louvres and their control gear in their open position, Fig. 5 is a view from the left hand side in Fig. 4, and Fig. 6 is a partial cross-sectional view on line 6-6 in Fig. 2.

With reference now to the accompanying drawings, the ventilators which are about to be described will be assumed to be mounted horizontally on a flat roof so as to serve as natural roof ventilators for providing day-to-day ventilation. It will be understood, however, that the ventilators may additionally, or alternatively, serve as automatically opening fire ventilators.

It will be further assumed that the leading edges of the louvres are their lower edges when the louvres are open, as shown in Fig. 4, the trailing edges of the louvres then lying at the top, as seen in Fig. 4.

While ventilators are being described in a horizorital or flat roof orientation, it will be readily understood that they may alternatively be mounted on a pitched roof structure so as to be downwardly inclined from left to right in Figs. 2,3 and 4, with all the louvres extending horizontally, as shown in Fig.

5, or again the ventilators may be mounted vertically in a wall structure, the left hand end of the ventilator in Figs. 2,3 and 4 then being the top of the ventilator.

Considering first Figs. 2 to 6, the ventilators comprise a rectangular body part or casing 10 presenting a base flange 11 for flashing the ventilator to the roof structure or the wall. An inner body part of the casing has two opposite pairs of parallel, upstanding walls 12 defining a rectangular ventilation opening 14 through the base flange 11. The body further comprises a pair of channel members 15 and a pair of channel members 16 disposed respectively along opposite sides of the inner body part. The channels 15 have a substantially greater width than the channels 16 and act as gutter means for water which runs off the outer surfaces of the louvres. The channel members 15 and 16 are welded to the casing 10 with one upstanding flange or wall abutting the outside of one of the walls 12 and the web or floor of the member abutting the base flange 11.

An outer body part or casing 20 of the ventilator is in the form of a rectangular duct having an outwardly directed flange 21 abutting the flange 11.The part 20 is secured to the outside of the upstanding flanges or walls of the channel sectioned members 15 and 16 remote from the walls 12, by means of rivets for example.

As shown in Fig. 6, one end of each channel member 15 which may be the lower end, opens through the outer body part 20 to drain off water outside the body of the ventilator onto the roof surface, a slot 22 being formed in the lower edge of the body part 20 to fit over the channel member.

Instead of being fitted horizontally, the ventilator, when in a flat roof position, may be fitted so as to slope at a very shallow angle, say 2a , from left to right in Fig. so that the channel members 15 slope downwardly towards their open ends.

The walls 12 each have an out-turned lip 1 2a to prevent water being blown up the walls 12 into the ventilation opening 14 when the ventilator is open.

Ventilation through the opening 14 is controlled by a series of parallel louvres 40 each of which is hinged for opening and closing movement about a hinge axis 41 disposed parallel to, and about midway between, its leading and trailing edges 44,45. The louvres are hinged on hinge pivots on the opposite longitudinal sides of the body part 20. Each louvre overlies the ventilation opening 14, which is positioned within the casing part 20, and well down inside the casing. This enables the louvres also to be positioned inside the casing 20, the casing acting as a windshield for the louvres when these are in an open position and preventing a return draught of air through the ventilator. The transverse dimension of the louvres is such that they span the opposed pair of walls 12 extending parallel with the channel members 15 at the exit from the ventilation opening 14.The louvres nevertheless, lie in an upwardly spaced relation to the opening when in their closed position. In their closed position, an outer, trailing edge portion 45' and an inner, leading edge portion 44' of each pair of adjacent louvres 40 overlap one another, the inner, leading edge portion of each louvre being turned upwardly as at 55, so as to extend towards the outer, overlapping trailing edge portion of the adjacent louvre, and then rearwardly as at 56, with respect to the outer, overlapping trailing edge portion, and the trailing edge portion of each louvre being turned downwardly, as at 64, so as to extend towards the inner, leading edge portion of the adjacent louvre thereby to enclose a transverse water channel 57 to lead water penetrating under rearwardly projecting trailing edge flanges 65 on the louvres over the side edges of the louvres into the channel members 15.To this end the louvres slope downwardly from their trailing edges towards their leading edges when in their closed position at an angle of about 8" when the ventilators are disposed horizontally.

The outer casing 20 is formed along its ends adjacent the channel members 16 with fixed portions 70,71 shaped substantially in accordance with the trailing and leading edge portions 45' and 44' respectively of the louvres 40, the fixed trailing-edgeshaped portion 70, overlying the leading edge portion 44' of the first louvre 40 at the left hand end of the ventilator shown in Fig. 2 and the fixed leadingedge-shaped portion 71 underlying the trailing edge portion 45' of the last louvre 40 at the right hand side in Fig. 2.

The transverse water channels 57 formed between the fixed portions 70,71 and the leading and trailing edge portions of the first and last louvres respectively lead water over the side edges of the first and last louvres respectively, into the gutter means 15.

In their closed position, the louvres 40 form a water shield covering over and weathering the opening 14, as is best appreciated by considering Figs. 3 and6.

Referring now to Fig. 1, in the particular ventilator construction there illustrated, the louvres 40 may have no side flanges. However, downwardly extending side flanges may be provided which are restricted to a portion only of the side edges of the louvres and which end short of the trailing edges of the louvres so as not to overlap or otherwise interfere with one another in the closed position of the louvres but instead, to leave open or exposed, the two ends respectively of each water channel 57.

One function of side flanges on the louvres 40 could be to pivot the louvres. Another function could be to connect the louvres to an operating link which interconnects the louvres to open and close the louvres in unison.

Attached to each of the opposite longitudinal sides of the body part 20 is a first sealing strip 100 extending horizontally, lengthwise thereof, the strips 100 being positioned at a level to engage with the side edges of the louvres and over a portion of each side edge of each louvre which extends from the trailing edge 45 of the louvre as far as the underlying or inner, leading edge portion 44' of the louvre. The side edges of the leading edge portions of the louvres do not engage the sealing strips 100 however, but lie inwardly of these strips on the side of the strips adjacent the channel members 15. Accordingly, the flow of water entering the channels 57 out of the ends of the channels 57 and into the gutter means 15 is not impeded by the sealing strips 100 which, nevertheless, act as seals to seal the gaps between the longitudinal sides of the body part 20 and the adjacent side edges of the louvres when the louvres are closed, as may be appreciated with reference to Fig. 3 which shows, however, a different form of the louvres.

The leading edge flange 56 of each louvre 40 carries a second flexible sealing strip, generally indicated at 105, which projects across the water channel 57 to engage with the inner surface of the downturned, trailing edge flange 64 of the adjacent louvre, and a similar second sealing strip 105 is provided on the corresponding flange formation of the fixed portion 71 to engage with the inner surface of the trailing edge flange 64 of the last or bottom louvre 40.

The second sealing strips 105 effectively seal the transverse air gaps between adjacent louvres and the first and last louvres and the body part of the ventilator. A substantially airtight design is thus provided which nevertheless drains water off the outer surfaces of the louvres.

The sealing strips 100 and 105 are composed of or comprise a close pile 106 of woven yarn of natural or synthetic fibre on a semi-rigid, plastics backing 107, the individual fibres of which have been treated with a water-repellent substance to prevent icing of the pile to the louvres. Preferably, silicone-treated polypropylene pile is used of a suitable pile height, which may be from 10 mm to 18 mm, the higher pile being used to seal the longitudinal gaps between the side edges of the louvres and the body part of the ventilator and the shorter pile being used to seal the transverse gaps between the louvres themselves, and between the first and last louvres and the ventilator body part.

By positioning the sealing strips 100 at the height of the side edges of the louvres 40, that is to say, the side edges of their outer surfaces, and allowing water to drain from the outer surfaces of the louvres under their trailing edges 45 and into the internal drainage channels 15, icing of the louvres may be substantially prevented, even when the ventilator is mounted in a horizontal position on a flat roof. By inclining the outer surfaces of the louvres towards their leading edges, in this horizontal position of mounting and by refraining from sealing the transverse air gaps between adjacent louvres at their trailing edge flanges 65, a positive draining of the outer surfaces of the louvres is achieved with the louvres in their closed position.

Whilst the sealing strips 105 could be repositioned so that the pile 106 extends upwardly from the flanges 56 or downwardly towards the flanges 56 for example, a sideways brushing and sealing action rather than a crushing, sealing action on the pile is preferred. As described, therefore, the flanges 64 move transversely relative to the pile 106 as the louvres are opened and closed and a sideways brushing and sealing action is achieved. Corres pondingly, a sideways brushing and sealing action is achieved between the pile 106 of sealing strips 100 and the side edges of the louvres.

The sealing strips 100 may be in short lengths car ried by the side edges of the louvres if desired.

Inasfar as the pile 106 is water-repellent, the strips 100 tend to confine standing water on the outer sur faces of the louvres when the louvres are closed.

However, any seepage of water between the sealed strips 100 and the side edges of the louvres is captured in the channel members 15 which underlie the sealing strips 100.

It is preferred to mechanically lock the sealing strips 100 to the opposite longitudinal sides of the body part 20, for example, by capturing the sealing strip backing in a dovetailed groove. The strips may, however, be stuck in place or mechanically fixed in any other way.

It will be noted that the sealing strips 105 are likewise mechanically locked to the leading edge flanges 55 and 56 of the louvres. The strips 105 comprise a channel-form mounting strip 110 of metal which presents a T-slot for mounting the strip of pile 106 on its backing 107, the channel flanges being of different heights and each having an inwardly directed flange 110', 110" at its free edge. The channel-form strip embraces the flanges 55, 56 with its higher channel flange and free edge flange 110' and is locked against the flanges 55, 56 by a rectangular sectioned metal locking bar tight fitted by being driven between the flange 55 and the flange 110". The T-slot may be formed in an inwardly directed flange carried at the free edge of the flange 56 if desired.

The form of ventilator illustrated in Figs. 2 to 6 is more fully waterproofed for flat roof mounting and is preferred. To this end, the louvres 40 are provided with depending side edge flanges 48 which extend forwardly from their trailing edges to end beyond their leading edges, as will be explained, the side edge flanges penetrating well down towards the drain channels 15 as best seen in Fig. 6. Each flange 48 is formed at its lower, leading edge corner with a lobe 50. An operating link 52 for the louvres is provided along each side, one immediately above and centrally disposed over each channel 15, and the lobes 50 along each side are all hinged to the adjacent one of these links.The links are connected con venientlythrough one or more of the louvres with further operating mechanism 120 in part shown in Fig. 6 for moving the links longitudinally thereby to pivot the louvres in unison about their hinge axes 41.

The links 52 are of channel section and receive the flanges 48 between their flanges as shown in Fig. 6.

The overlap of the leading and trailing edge portions of adjacent louvres extends to the flanges 48 in the present embodiment. Thus, the flanges 48 of adjacent louvres 40 also overlap. To permit this overlapping of the flanges 48, the side edges of the louvres diverge slightly from their leading to their trailing edges so that the flanges 48 are spaced apart where they overlap. Because of the overlap of the flanges 48, the ends of the water channels 57 are confronted by portions of the flanges 48 in this construction and communicate with passages 112 formed between the overlapping portions of the flanges 48 which lead water downwardly into the channels 15.

The flanges 48 together with the links 52 form depending wall formations in the closed position of the louvres to the outside of, and extending along the whole length of, the opposed walls 12 adjacent the channels 15. The sealing strips 100, in this con struction, engage against the outsides of these wall formations. The ends of the water channels 57 open over side edge portions of the louvres extending from their leading edges to communicate with the sides of the sealing strips 100 adjacent the channel members 15 via the passages 112. Accordingly, the lower edges of the sealing strips 100 are not necessarily disposed at a level above the floors of the water channels 57 in this construction and the sealing strips 100 may be located at a somewhat lower level if desired.However, to prevent icing, the presence of water traps in channels formed between the side flanges 48 of the louvres and the body part of the ventilator is to be avoided.

In the construction of Figs. 2 to 6, the sealing strips 105 are replaced by sealing strips 105' mounted on the undersides of the outer, overlapping trailing edge portions 45' of the louvres. The arrangement of sealing strips 105 as described with reference to Fig.

1 is, however, preferred.

As may be seen particularly from Figs. and 6, each sealing strip 100 has a backing strip 107 mechanically locked in a groove 113 of dovetail shape in cross-section, roll formed in a mounting plate 114 r wed to the body part of the ventilator.

The mounting plates 114 carry pivot pins 115 for the louvres immediately below the grooves 113.

The louvres may be partially opened while still weathering the opening 14 to some extent since rain falling on the outer surfaces of the louvres may then drain down those outer surfaces into the gutters formed by the leading edge flanges 55,56 of the louvres which lead the water transversely into the channels 15 from which it flows out onto the outer surface of the roof.

By positioning the louvres vertically as shown in Fig 4, a substantially clear opening to the sky is provided through the opening 14.

Some variants of the sealing arrangements between overlapping louvre portions have been represented in Fig. 4 for the two central louvres in the Figure. The right hand central louvre in this Figure has a dovetail fold 8 in its flange 64 for a flexible sealing strip 105" extending along the whole length of the louvre. This strip strikes against the flange 55' at the leading edge of the adjacent louvre which is without a return flange 56 in this case.

The arrangement of Fig. 1 is, however, preferred for its labyrinth path between the overlapping louvre portions which improves the sealing action to prevent draughts and the entry of dust and to improve the soundproofing effect.

The left hand central louvre in F;g. 4 shows a further variation for positioning the sealing strips 105 on the louvres in a fold 8' in a downturned portion of the flanges 56. This may be combined with a sealing strip 105' as shown at the trailing edge of the left hand central louvre in Fig. 4. further variation is to combine the sealing strips 105", 105 shown respectively at the trailing and leading edge portions of the right and left hand central louvres in Fig. 4.

In all the embodiments described the sealing strips 105 lie within the profile of louvres when open so that they do not form an additional obstruction to the outflow of air through the ventilators.

Claims (13)

1. A louvred ventilator comprising a plurality of louvres hingeably movable to control ventilation through a ventilation opening of the ventilator, the louvres overlying and spanning an opposed pair of walls defining one pair of opposite sides of the opening to drain water on the outer surfaces of the louvres over said walls to the outside thereof, the louvres overlapping one another in their closed position to define a transverse water channel between an inner, leading edge portion of each louvre and an outer, trailing edge portion of the next adjacent louvre and flexible sealing strips carried by the louvres and disposed lengthwise of the louvres to engage between the overlapping portions of the louvres at locations spaced from the leading and trailing edges of the louvres.

2. A louvred ventilator as claimed in claim 1 in which the sealing strips project across the water channels.

3. A louvred ventilator comprising an outer body part of casing defining a duct, a ventilation opening defined within the duct between an opposed pair of walls of an inner body part or casing within the duct, a plurality of louvres hingeably movable to control ventilation through the ventilation opening, the louvres overlying and spanning said opposed pair of walls to drain water on the outer surfaces of the louvres over said walls into gutter means in said duct and leading outside said duct, the louvres overlapping one another in their closed position to define a transverse water channel between an inner leading edge portion of each louvre and an outer trailing edge portion of the next adjacent louvre, first flexible sealing strips positioned to engage between said outer body part and portions of the side edges of the louvres extending from their trailing edges, when the louvres are in their closed positions, and second flexible sealing strips carried by the louvres and disposed lengthwise of the louvres to engage between the overlapping portions of the louvres at locations spaced from the leading and trailing edges of the louvres, said transverse water channels opening at their two ends respectively over side edge portions of the louvres extending from their leading edges to communicate with the side of said first flexible sealing strips adjacent said gutter means.

4. A ventilator as claimed in claim 3 in which said first said flexible sealing strips are disposed on said outer body part and said side edge portions of the louvres extending from their leading edges are positioned on the side of the first said flexible sealing strips adjacent said gutter means.

5. A ventilator as claimed in claim 3 in which said transverse water channels communicate with the side of said first said flexible sealing strips adjacent said gutter means via passages formed between overlapping portions of depending side flanges of adjacent louvres at their leading and trailing edges respectively.

6. A ventilator as claimed in any preceding claim in which the flexible sealing strips are composed of or comprise a pile of woven yarn or natural or synthethic fibre which has been treated with a water- repellent substance.

7. A ventilator as claimed in claim 6 in which the pile is of silicone4reated polypropylene fibres.

8. A ventilator as claimed in claim 6 or7 in which the pile has a height of 10 mm to 18 mm.

9. A ventilator as claimed in any preceding claim in which the flexible sealing strips are mechanically secured in place.

10. A ventilator as claimed in claim 9 in which the sealing strips or some of them are provided with backings slid into dovetail folds or slots thereby to secure them in place.

11. A ventilator as claimed in any preceding claim in which some at least of the flexible sealing strips carried by and disposed lengthwise of the louvres are supported at the edges of rearwardly directed flanges at the leading edges of the louvres to engage downturned trailing edge flanges of the louvres.

12. A ventilator as claimed in any preceding claim 1 to 10 in which a pair of said flexible sealing strips is carried by and disposed lengthwise of each louvre, the flexible strips on adjacent louvres extending perpendicular with respect to one another and being secured adjacent the edges of the overlapping portions of the louvres.

13. A ventilator substantially as any one of the specific embodiments hereinbefore described with reference to the accompanying drawings.