CHIMNEY COWLS

Abstract: The cowl comprises a hood (10) having a flat top portion (11) and a downwardly and outwardly extending peripheral por­ tion (12), there being provided a series of openings (15) dis­ posed around the periphery of the flat topped portion (11). An annular, channel (18) is disposed below the hood (10) with its top opening upwardly beneath the openings (15). A gap (20) is formed between the outer wall of the channel (18) and the edge (23) of the portion (12) of the hood for the discharge of smoke and chimney gases. The hood (10) is carried from the channel (18) by brackets (30) and the channel (18) is adapted with hook bolts (25) for fastening to the chimney stack (24).

Description: IMPROVEMENTS IN CHIMNEY COWLS This invention relates to chimney cowls. A chimney cowl is usually fitted to reduce downdraught in the chimney and to reduce the entry of rain into the chimney flue. Simple chimney hoods are known which cover over the chimney opening to reduce direct rain entry. Also known are cowls which are capable of reducing downdraught for given wind directions, bearing in mind not only that a chimney may be sheltered from wind blowing from certain quarters and be subject to prevailing winds but also that wind may blow horizontally across the top of a chimney or at an angle either upwardly or downwardly with respect to the horizontal. Such cowls need to be properly orientated with respect to the chimney to obtain the best results depending upon the prevailing wino direction. An object of this invention is to arrive at an improved chimney cowl which is more effective to prevent rain entry into a chimney flue and which is effective to prevent or reduce downdraught in a chimney irrespective of the wind direction. According to this invention, a chimney cowl comprises a hood, the hood having a flat top portion and a downwardly and outwardly extending peripheral portion, there being provided a series of openings disposed around the periphery of the flat top portion of the hood, an annular, channel-form member disposed below the hood in downwardly spaced relation thereto and dimensioned and arranged so as to lie with its channel top opening upwardly directly beneath said openings to enable said channel to collect precipitation falling through said openings, an annular gap being formed between the upper, peripheral edge of the outer wall of the channel-form member and the peripheral edge of the downwardly and outwardly extending peripheral portion of the hood, and means for securing the cowl to a chimney with the channelform member encircling the chimney opening. Preferably, the securing means is carried by the channel-form member and the channel-form member supports the hood. Conveniently, the channel-form member is circular in shape and said openings are arranged in a circular ring. A tubular bird guard may be provided, the bird guard being in one piece and being held in position between the underside of the hood and the floor of the channel in the channel-form member, the bird guard surrounding the inner wall of the channel-form member and extending upwardly from the upper peripheral edge thereof to engage the underside of the hood. With this arrangement, the bird guard, if provided, is securely retained in the cowl and cannot readily fall into the flue and cause a blockage. A specific embodiment 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 front elevation of a chimney cowl according to the present invention; FIGS. 2 and 3 are respectively top plan and underneath plans of the cowl; and FIG. 4 is a section on line 4-4 in Fig. 2. With reference now to the accompanying drawings, the cowl comprises a hood 10 having a circular, generally flat top portion 11 and a downwardly and outwardly extending peripheral portion 12, there being provided a series of four, elongated openings 15 disposed around the periphery of the flat topped portion 12 of the hood in a circular ring. An annular, channel-form member 18 of circular shape is disposed below the hood in downwardly spaced relation thereto. The channel-form member 18 is dimensioned and arranged so as to lie with its open channel top facing upwardly directly towards the openings 15 to enable the channel to collect precipitation falling through the openings. A directly downwardly facing annular gap 20 is formed between the upper, peripheral edge 22 of the outer wall of the member 18 and the peripheral edge 23 of the portion 12 of the hood. Hook bolt means 25 is provided for securing the cowl to a chimney 24 with the member 18 encircling the chimney opening 25. The hook bolt means is carried by the member 18 and comprises four radially disposed hook bolts 27 at 900 angles which are passed through opposite holes in the inner and outer walls of the member 18 respectively. The ends of the hooks 27' are engaged with the inner surface of the chimney with the cowl centred over the chimney opening and the wing bolt nuts 28 are then tightened evenly so as to draw the hooks into firm engagement with the chimney inner surface and thereby secure the cowl in place. The member 18 supports the hood 10 via four U-shaped brackets 30 screw fixed, as at 31 and 32, to the floor of the channel-form member 18 and the flat top portion 11 of the hood respectively and to the latter at locations between the adjacent ends of adjacent openings 15. The horizontally extending limbs 33, 34 of the brackets 30 are directed radially outwardly and the vertically extending portions 34 of the brackets are spaced from the inner wall of the channel-form member 18. The gap thus provided receives and locates the lower edge portion of a hollow, right cylindrical, one piece, bird guard 40 formed of wire mesh. The bird guard 40 extends upwardly to engage the under side of the flat-topped portion 11 of the hood and is held loosely in a central position between the underside of the hood and the floor of the channel in the channel-form member by the brackets 30. The limbs 33, 34 of the brackets 30 are provided with lugs 41, 42 which locate in holes 45 and 46 respectively in the hood and in the outer wall of the member 18, the latter forming drain holes for draining water collected in the channel of the member 18 to the outside of the chimney opening. The outer wall of the member 18 is upwardly and outwardly curved towards the peripheral edge of the peripheral portion 12 of the hood to improve the weathering and the fact that the gap 20 between the wall and the hood is downwardly facing prevents the direct entry of wind under the hood for most conditions. At the same time, this gap 20 is made adequate enough to provide for the exit of smoke and not unduly to increase the resistance to flow of air up the chimney flue. The central portion 11 of the hood is slightly domed in an upward direction to to strengthen the hood against buckling and to cause water to run off the top of the hood while the openings 15 are provided each with a surrounding upturned lip to prevent water draining through the openings. In use of a chimney cowl as described, wind striking the hood from any direction and being deflected across the top of the hood and across the openings 15 gives rise to an aspirating effect improving the updraught through the chimney. Due to the symmetrical shape of the hood, this is done regardless of the general direction of the wind. The cowl substantially covers over and shelters the chimney opening to prevent downdraughting under adverse wind conditions and also acts to prevent or reduce rain penetration into the chimney flue, precipitation falling through the openings 15 being collected and drained off to the outside of the chimney opening by the channel member 18. The cowl as described is of "knock-down" construction and can be assembled on site using the fixing screws described. In installing the cowl it is unnecessary to "direct" the cowl to suit prevailing wind conditions. The cowl is easy to fit and requires no tools. The channel-form of the member 18 constituting the base of the cowl and carrying the hook bolt fixings provides sufficient rigidity to resist distortion under the action of the forces exerted by the hook bolts attaching the cowl to the chimney. Whilst a circular cowl has been described by way of example, this is not essential. A generally square-form cowl, as viewed in plan, is within the scope of this invention and could be provided to suit square chimney flues. Alternatively, a tubular adapter could be provided for converting a square chimney flue into a round section to suit the circular cowl described. The cowls may be provided in various sizes to suit chimney flues of various dimensions. It is to be understood, however, that the hook bolt fixings enable a cowl of any given dimensions to be fitted to quite a wide range of flue sizes. The channel-form member 18 might conceivably be of inverted channel-form or replaced with 2 closed or solid-sectioned annular member which will equally perform the rigidifying function of the channel-form member 18. Such 2 closed or solid-sectioned or inverted channel-form member might have its upwardly facing or top surface directly beneath the openings 15 adapted simply to drain off water outwardly of the opening to the top of the chimney flue. In any event, it would be preferred to provide the inverted channel-form or closed or solidsectioned member with an upwardly and outwardly curved wall surface corresponding to that at the outer wall of the member 18. With reference to the construction of chimney cowl as described in the last but one paragraph above it is within the scope of the present invention to provide a chimney cowl comprising a hood, the hood having a flat top portion and a downardly and outwardly peripheral portion, there being provided a series of openings disposed around the periphery of the flat top portion of the hood, an annular frame member disposed below the hood in downwardly spaced relation thereto, an annular gap being formed between the frame member and the peripheral edge of the downwardly and outwardly extending peripheral portion of the hood, support means supporting the hood from the frame member, and securing means carried by the frame member for securing the cowl to a chimney with the frame member encircling the chimney opening. Preferably, in this case, the frame member would have its upwardly facing top surface disposed directly beneath said openings and adapted to drain off water outwardly of the chimney opening.

Claims: CLAIMS: 1. A chimney cowl comprising a hood, the hood having a flat top portion and a downwardly and outwardly extending peripheral portion1 there being provided a series of openings disposed around the periphery of the flat top portion of the hood1 an annular, channel-form member disposed below the hood in downwardly spaced relation thereto and dimensioned and arranged so as to lie with its channel top opening upwardly directly beneath said openings to enable said channel to collect precipitation falling through said openings, an annular gap being formed between the upper, peripheral edge of the outer wall of the channel-form member and the peripheral edge of the downwardly and outwardly extending peripheral portion of the hood, and means for securing the cowl to a chimney with the channel-form member encircling the chimney opening. 2. A chimney cowl as claimed in claim 1 in which the securing means is carried by the channel-form member and the channel-form member supports the hood. 3. A chimney cowl as claimed in claim 1 or 2 in which said openings are arranged in a circular ring. 4. A chimney cowl as claimed in any preceding claim further comprising a tubular bird guard, the bird guard being in one piece and being held in position between the underside of the hood and the floor of the channel in the channel-form member, the bird guard surrounding the inner wall of the channel-form member and extending upwardly from the upper peripheral edge thereof to engage the underside of the hood.

Inventors: BURTENSHAW, RAYMOND ALFRED FRANK
Applicants: COLT BUILDING PRODUCTS LIMITED
Application year: 1985
Main classification: F23L17
IPC codes: F23L17