GB2211287A

GB2211287A - Roof ventilator

Info

Publication number: GB2211287A
Application number: GB8724382A
Authority: GB
Inventors: Alan Bell
Original assignee: STEELPRESS
Current assignee: STEELPRESS
Priority date: 1987-10-17
Filing date: 1987-10-17
Publication date: 1989-06-28
Anticipated expiration: 2007-10-17
Also published as: GB8724382D0; GB2211287B

Abstract

A natural-draft ventilator (1) is provided for mounting at an air aperture (7) on a roof (2) of a building. The ventilator (1) comprises an elongate casing structure defining a longitudinal air inlet (6) for positioning at the air aperture (7) and longitudinally extending air discharge means (13, 14), the casing structure providing air passage means (11, 12) between the air inlet (6) and the air discharge means (13, 14). Secondary air discharge means (16, 17), for example in the form of louvres, are provided on the casing walls and open onto the air passage means. Barrier means are also formed by the casing walls to prevent ingress of water to the air inlet (6) from either of the primary or secondary air discharge means. <IMAGE>

Description

VENTILATOR Description The present invention relates to ventilators and in particular to natural-draft roof mounted ventilatoiss for buildings, especially industrial buildings.

It is known to use natural-draft ventitators mounted on the roof of industrial buildings eg. factories. Since these ventilators function by means of natural draft effect they are usually mounted at the apex or ridge of the building roof so as to be at the highest point of the building, and these ventilators are preferably of elongate form extending along a substantial portion of the roof ridge so that satisfactory ventilation performance may be achieved.

In one such prior art ventilator, the ventilator comprised an elongate casing structure of canopy form for location over an air discharge aperture at the ridge or apex of a roof of a building, said casing structure including a lower air inlet at said air discharge aperture and a top air discharge vertically above said air inlet.

Further, baffle means housed in the casing structure between the air inlet and the top air discharge served to prevent water ingress to the air inlet (and hence to the interior of the building) from the top discharge, discharged air flowing from the air inlet to the top discharge being deflected around and through said baffle means. Water discharge openings were located at the bottom end of the casing structure for the escape of any water caught by the baffle means. A pivoting damper and air flow control plate was usually provided at the air inlet.

The performance of a natural-draft roof mounted ventilator can be measured in terms of the volume of air discharged through the ventilator by natural draft effect per unit length of the ventilator. This performance is dependent to a large degree on the size of the air inlet and the air discharge. In the previous ventilator as described above, it has proved difficult to increase the air outlet area to give improved performance since this gives rise to difficulties in preventing water ingress to the building via the ventilator.

It is an object of the present invention to provide a natural-draft ventilator of improved performance.

According to the present invention a natural-draft ventilator for mounting at an air aperture on a roof of a building comprises a casing structure defining an air inlet for location at said air aperture and a primary air discharge means; the casing structure providing an air passage between said air inlet and the primary air discharge means; secondary air discharge means in or beside the air flow path between the air inlet and the primary discharge means, and means to preclude water ingress to the air inlet from either of the air discharge means.

Preferably said secondary air discharge means comprises louvred vents on at least one wall of the casing structure.

Preferably barrier wall means are provided facing said secondary air discharge means to preclude water flow from the secondary air discharge means to the air inlet.

Preferably the primary air discharge means are downwardly facing while the casing structure has an outer wall portion of canopy form serving to deflect air downwardly towards said downwardly facing primary air discharge means.

In a preferred embodiment the casing structure includes a plurality of laterally-spaced longitudinally extending plate members, air passages being defined between pairs of said plate members, the plate members including sets of louvred openings defining said secondary air discharge means. The space between opposed bottom edges of adjacent plate members can define said primary air discharge means.

Preferably an inner plate member provides a barrier wall means facing a set of louvred openings on an adjacent but outwardly positioned plate member, said barrier wall means serving to preclude water flow to the air inlet from said louvred openings.

Preferably the bottom edge of one plate member is located at a tower level than the bottom edge of an adjacent outer plate member, said outer plate member including a set of touvred openings located at a higher level than a louvred opening set on the adjacent inner plate member.

Preferably the air inlet is defined between an opposed pair of longitudinally extending walls of the casing structure, and the various longitudinal walls of the structure are preferably held in spaced relationship by means of opposed end walls. The opposed longitudinal wall pair can carry shoulder plates to facilitate the attachment of the casing structure to a building roof.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Fig. 1 is a pictorial view of part of a roof ventilator according to the present invention; Fig. 2 is a sectional elevation of the ventilator of Fig. 1; and Fig. 3 shows part of a secondary vent system of the ventilator in greater detail.

Referring to the drawings, a natural draft roof ventilator 1 is adapted for mounting at the ridge of a building roof 2. The ventilator 1 is in the form of a casing structure comprising longitudinally extending plate members carried by an opposed pair of end plates 3 (only one shown in Fig. 1). Opposed walls 4, 5 define an air inlet 6 to the casing structure which inlet 6 is located over an air discharge aperture 7 at the ridge of roof 2, while the top of the casing structure comprises a canopy 8, preferably of two part constructions 8A, 88 when the width of the casing is above a particular size, and including vertical side walls 9. Intermediate each wall pair 4/9, 5/9 is a partition wall 10 whereby outer air passages 11 are provided between the walls 9, 10 and inner air passages 12 between the walls 4, 10 (and 5, 10). The passages 11, 12 Lead to downwardly opening air discharges 13, 14 respectively defined between the bottom edges of walls 9, 10 and between the bottom edge of walls 9 and walls 4, 5 respectively, the air discharges 13, 14 defining primary air discharge means of the ventilator 1. The walls 4, 5 carry shoulder plates 15 to facilitate fitting of the ventilator 1 to the roof 2.

In addition to the primary air discharge means, the ventilator 1 also includes secondary air discharge means in the form of sets of louvred openings or perforations 16, 17 on the walls 9, 10 respectively. As best seen in Fig. 3 the louvre plates 16A (17A) of the openings 16 (17) extend downwardly at a suitable angle to shield the openings 16 (17) from downwards or sideways directed rain.

The louvred openings 16, 17 can be conveniently formed by stamping the walls 9, 10 and indeed all of the parts of the casing structure can be made by a suitable metal pressing operation. The casing parts can be made of steel or aluminium sheet and the various longitudinal walls can be joined to the end walls 3 by means of rivets.

The top of walls 4, 5 comprise outwardly turned apertured flanges 4A, 5A while the bottom of the walls 9, 10 comprise inwardly turned apertured flanges 9A, 10A flange 10A being at a lower level than flange 9A As can be seen in Fig. 2 the sets of louvred openings 16, 17 are vertically staggered and the wall 10 provides a non-perforated barrier wall portion 108 facing openings 16 to preclude any rain which penetrates the openings 16 from passing to the inlet 6 (and hence to the interior of the building) while the walls 4, 5 constitute similar barriers vis-avis the openings 17.Airflow through the ventilator 1 is by natural-draft effect ie. by convection flow and/or by pressure differential action and the dashed arrows in Fig. 2 show the passage of air through the ventilator from the air discharge 7 on the roof 2: thus the canopy 8 causes the airflow to be turned into the passages 11, 12 whence the air passes to atmosphere via the primary and secondary air discharge means. The ventilator 1 can be adapted to be fitted to a wide variety of roof patterns and in particular roofs with corrugated roof sleeting The combination of the primary air discharge ie.

discharges 13, 14 and the secondary air discharge ie.

louvred openings 16, 17 provide increased air discharge area in comparison with comparable prior art ventilators, and this gives rise to increased performance in the ventilator. The ventilator can have a relatively low profile height and the ventilator will not unduly detract from the architectural aesthetics of the building, this latter characteristc being enhanced by the symmetrical, ie. ridge, location of the ventilator.

Claims

1. A natural-draft ventilator for mounting at air aperture on a roof of a building comprising a casing structure defining an air inlet for location at said air aperture and primary air discharge means; the casing structure providing an air passage between said air inlet and the primary air discharge means; secondary air discharge means in or beside the air flow path between the air inlet and the primary discharge means, and means to preclude water ingress to the air inlet from either of the air discharge means.

2. A ventilator as claimed in claim 1, wherein said secondary air discharge means comprises louvred vents on at least one wall of the casing structure.

3. A ventilator as claimed in claim 1 or 2, wherein barrier wall means are provided facing said secondary air discharge means to preclude water flow from the secondary air discharge means to the air inlet.

4. A ventilator as claimed in any one of the preceding claims, wherein the primary air discharge means are downwardly facing while the casing structure has an outer wall portion of canopy form serving to deflect air downwardly towards said downwardly facing primary air discharge means.

5. A ventilator as claimed in any one of the preceding claims, wherein the casing structure includes a plurality of laterally-spaced longitudinally extending plate members, air passages being defined between pairs of said plate members, and the plate members including sets of louvred openings defining said secondary air discharge means. The space between opposed bottom edges of adjacent plate members defining said primary air discharge means.

6. A ventilator as claimed in claim 5, wherein an inner plate member provides a barrier wall means facing a set of louvred openings on an adjacent but outwardly positioned plate member, said barrier wall means serving to preclude water flow to the air inlet from said louvred openings.

7. A ventilator as claimed in claim 5 or 6, wherein the bottom edge of one plate member is located at a lower level than the bottom edge of an adjacent outer plate member, said outer plate member including a set of louvred openings located at a higher lever than a louvred opening set on the adjacent inner plate member.

8. A ventilator as claimed in any one of the preceding claims, wherein the air inlet is defined between an opposed pair of longitudinally extending walls of the casing structure, and the various longitudinal walls of the structure are preferably held in spaced relationship by means of opposed end walls.

9. A ventilator as claimed in claim 8, wherein the opposide longitudinal wall pair carries shoulder plates to facilitate the attachment of the casing structure to a building roof.

10. A natural-draft ventilator substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.