NL2036874B1 - Chimney cap for extinguishing a chimney fire - Google Patents

Abstract

The invention relates to a chimney cap for extinguishing a chimney fire. The chimney cap has a frame that is configured to be installed on a chimney, Where a flue pipe of the chimney can enter the frame through an opening. The chimney cap also has a guiding assembly fixed to the frame, and a sealing device that is movable with respect to the frame along the guiding assembly between a first position and a second position. In the first position the sealing device is at a relatively large distance from the opening, thereby allowing flue gas to exit the flue pipe through the chimney cap, While in the second position the sealing device is at a relatively small distance from the opening, so as to at least partially seal the flue pipe by beating against it. According to the invention, the guiding assembly leaves the opening clear.

Description

CHIMNEY CAP FOR EXTINGUISHING A CHIMNEY FIRE

The invention relates to a chimney cap for extinguishing a chimney fire, comprising a frame that is configured to be installed on a chimney, the frame defining an opening on one end of the frame, the opening being configured to receive a flue pipe of the chimney and defining an opening axis normal to the opening, a guiding assembly fixed to the frame. and a sealing device that is movable with respect to the frame along the guiding assembly between a first position and a second position, wherein in the first position the sealing device is at a relatively large distance from the opening, thereby allowing flue to exit the flue pipe through the chimney cap, and wherein in the second position the sealing device is at a relatively small distance from the opening, so as to at least partially seal the flue pipe by bearing against it.

Such a chimney cap is in itself known from FR 544.465 A. Chimney cap is used to limit damage caused by a chimney fire, by extinguishing it by blocking the flue pipe. Chimneys can ignite during operation due to several reasons, such as the buildup of soot and/or an excess use of fuel. The fire can have dire consequences, depending on the location of the chimney, and how fast the fire can be extinguished. The cap known from FR 544.465 A blocks the flue pipe in case of a fire, which results in less oxygen being available. Accordingly, the fire will be smothered and ultimately extinguished. FR 544.465 A makes use of fusible supports to hold a sealing means in place away from the flue pipe. In case of a chimney fire, the supports melt, causing the sealing means to fall down to block the flue pipe. The closing means is carried by and guided by guiding means.

The design proposed in FR 544.564 A has the disadvantage, that due to the exposure to smoke and soot, in flue gases from the flue pipe, the guiding means may be contaminated reducing its effectiveness. In the worst case, the guiding means may actually block the closing means from moving towards the flue pipe, thereby inhibiting the function of blocking the flue pipe. Such a failure would normally only be spotted during or after the chimney fire, because in normal operation the guiding means are not used. The design of FR 544.564 A is therefore fundamentally unreliable. Compensation has to date only been possible via regular inspection, which may still be insufficient at worst, and labor intensive and/or dangerous and best.

It is therefore an object of the invention to provide a more reliable chimney cap.

The object is achieved by a chimney cap according to the preamble, wherein the guiding assembly leaves the opening in the frame clear.

Accordingly, interaction between flue gas leaving the chimney and the guiding assembly is reduced. This reduced interaction may result in a smaller deposition of soot and other contamination on the guiding assembly, possibly ensuring a more reliable functioning.

Additionally or alternatively, the flue pipe may be used more effectively, since it is not partially blocked by the guiding assembly.

At least partially closing the flue pipe in case of a chimney fire may contribute to the chimney fire being detected by smoke detectors already installed inside the establishment having the chimney. In many cases. such smoke detectors are required by law, and/or installed for safety reasons. However, under many circumstances, smoke detectors inside the establishment may not detect a chimney fire in an early stage, because the chimney fire starts inside the chimney only, and flue gases exit through the chimney as well. Therefore, the smoke detectors may be ill-positioned to detect a chimney fire. However, when the chimney is closed, or put more accurately, when the flue pipe is at least partially closed during the chimney fire by the chimney cap described herein, flue gases in case of a chimney fire will also flow downwards through the chimney. thereby entering the establishment. Accordingly, the smoke detectors can detect the flue gases in a relatively early stage. Thus, the chimney cap is not only relatively reliable, but also boosts safety by allowing easier detection of chimney fires via readily available smoke detectors.

In particular, the guiding assembly may be arranged radially outside the opening, with respect to the opening axis. This, however, does not necessarily mean in a circular pattern. In fact, the flue pipe and the opening may be of any suitable cross sectional shape.

By placing the guiding assembly outside of the opening, it will be further away from the source of the flue gases, thereby reducing interaction, further lowering the chance of failure occurring in the guiding assembly. Moreover, radially away from the opening flue gases may have cooled somewhat, reducing the amount of deposition on the guiding assembly when interaction does take place.

Preferably, the guiding assembly is arranged radially outside of a space defined by a projection of the opening along the opening axis. preferably towards an end of the chimney cap opposing the one end and/or away from that opposite end beyond the one end.

By not only keeping the guiding assembly outside of the flue pipe, but also out of the space above and/or below it, even less interaction takes place.

In an embodiment of the invention, the chimney cap further comprises a release mechanism, which comprises: - a locking mechanism movable between a locking position, in which it locks the sealing device with respect to the guiding assembly, and an unlocking position, in which the sealing device is free to move with respect to the guiding assembly; and - an actuation mechanism, configured for actuating the locking mechanism from the locking position to the unlocking position in case of a chimney fire.

Under normal operation, when a chimney fire is not occurring, the chimney and in particular its flue pipe is behaving as normal, i.e. it exhausts flue gases. In this situation, the chimney cap and thus the sealing device will still be present but do not interfere with the ability of the chimney exhaust flue gases.

In particular the actuation mechanism can comprise at least one bias member biasing the locking mechanism to the unlocking position; and a fusible clasp keeping the locking mechanism inthe locking position, the fusible clasp being configured to fail due to melting or softening when exposed to elevated temperatures occurring during a chimney fire, thereby releasing the locking mechanism; and/or a heat deformable clasp keeping the locking mechanism in the locking position, the heat deformable clasp being configured to deform when exposed to elevated temperatures occurring during a chimney fire, thereby releasing the locking mechanism.

The fusible clasp and/or heat deformable clasp may be configured such that it will not fail or deform to unlock the locking mechanism when there is no chimney fire, by choosing a material and design that has suitable thermal properties. In particular, fusible lead parts are available and are considered herein.

In any case, due to using a deformable or fusible clasp, actuation may be both reliable and passive, thereby further improving the reliability of the chimney cap. In comparison, detection of a chimney fire through electronic smoke detectors or other electronic/electric methods may fail under certain circumstances, for instance if the sensors emploved are contaminated by deposits such as soot. Using a heat sensitive clasp, such as the fusible clasp or the heat deformable caps, however, may be more reliable, as the temperature during a chimney fire is typically elevated, thus activating the release mechanism without problems.

In an embodiment of the invention, the fusible clasp or heat deformable clasp is arranged on a side of the sealing device which faces the opening.

Accordingly, the clasp faces the flue pipe directly, and may therefore be more exposed to heat generated in a chimney fire. Accordingly, the reliability may be further increased by increasing the odds of successfully triggering the release mechanism.

It may be advantageous to have a shield arranged between the fusible or heat deformable clasp and the opening in the frame.

The shield may shield (i.e. protect) the clasp from the temperatures of the flue gas during normal operations, i.e. when there is no chimney fire, thus lowering the risk of accidental activation of the release mechanism. Additionally or alternatively, the shield may reduce contamination of the clasp. In case of a chimney fire, typical temperatures are so much elevated, that the shield no longer provides protection and the fusible / deformable clasp will indeed melt or deform.

In vet another embodiment of the invention, the actuation mechanism is configured so that a biasing force from the bias member acts upon the clasp as a tensile force. This can be achieved by connecting a pretensioned spring in series with the fusible clasp, thus also putting a tensile force on the clasp.

The tensile force causes the clasp to be pulled apart when melting, increasing the likelihood of unlocking the release mechanism. Reliability may thereby be improved.

Alternatively, when put under compression, molten or softened parts of the clasp might come in contact with e.g. the mechanism, and result in an inability to unlock, thus preventing the sealing device from moving and being unable to extinguish the chimney fire.

In particular, the sealing device may carry the release mechanism. By having the sealing device carry the release mechanism, said sealing device will be weightier. This may be advantageous when gravity is the main acting force for movement from the first to the second position, as this will mean that there is a larger chance of the sealing device falling instead of being stuck, as may be the case with the prior art design of FR 544.465 A.

In an embodiment of the invention, the locking mechanism is located on a side of the sealing device which faces away from the opening, wherein additionally or alternatively the bias member, if it is provided. is provided on that side.

This means the locking mechanism, and/or the bias member, may experience less exposure to flue gases, thereby possibly further reducing the risk of failure and improving reliability accordingly.

In another embodiment of the invention the locking mechanism comprises at least one sliding member, which in the locking position engages the guiding assembly for locking the sealing device.

Using a sliding member is an elegant solution that enables the clasp and locking mechanism to be on separate sides of the sealing device and it may be relatively cost effective compared to more complex constructions.

In yet another embodiment of the invention the at least one sliding member comprises a planar main body and at least one reinforcing rib.

The force applied by the actuation mechanism, especially in the case a constant force is applied by the pretensioned bias member, can lead to deformations in the sliding member if no reinforcement is applied. Because such deformations could cause malfunctions, the reinforcing ribs contribute to reliability exactly by avoiding or reducing the deformation.

Preferably, not only one reinforcing rib is used, but two at a mutually perpendicular angle.

Deformation in multiple directions may be countered accordingly.

In particular, the guiding assembly can define a recess for receiving the at least one sliding member, the recess being tapered in a direction away from the sliding member.

This may have one or both of the following two advantages, the first being that it may provide as self-centering action by when the sliding member is pretensioned into the recess. Due to the tapering shape, the sliding member will be forced towards a preferred position in the recess, thereby centering the sliding member. Secondly, the tapered shape may reduce the drag on the sliding member when being released to the second position. After all, as soon as the sliding member slides somewhat out the recess, the available cross sectional space for the sliding member 5 is increased due to the taper, thereby reducing or even avoiding drag forces which could otherwise form between sliding member and guiding assembly.

The sealing device may be provided with e.g. flat ends, for instance for interaction with the guiding assembly.

In an embodiment of the invention the sealing device has a larger cross section than the opening as seen perpendicular to the opening axis.

This may ensure that the flue pipe will be properly sealed, while possibly also preventing the sealing device from falling into the chimney.

The sealing device optionally comprises on a side facing the opening a protrusion extending circumferentially at a distance radially inwards from a circumference of the sealing device.

This may have one or more advantages, for instance the following. Firstly, the protrusion may aid a sealing interaction with the flue pipe, thereby increasing efficacy of the sealing device.

Secondly, the protrusion may be used to further increase the weight of the sealing device. The latter effect may be exacerbated when the protrusion is provided in a planar construction of the sealing device. In such a case, the sealing device may be planar, and the protrusion may be provided by a smaller plate mounted on the primary sealing plate. Regardless of whether or not the protrusion is provided. the sealing device may be planar, for instance mate of a plate. e.g. sheet metal. Additionally or alternatively the sealing device may have a layered structure.

In another embodiment of the invention the guiding assembly comprises one or more, preferably four, guiding profiles placed around the chimney, wherein said guiding profiles extend substantially parallel to the opening axis.

By increasing the number of guiding profiles, the reliability of the system may be improved, by providing a more accurate and constraining guide for the sealing device. Moreover, by having the guide profiles extend vertically, an elegant structure may be obtained.

In yet another embodiment of the invention the chimney cap further comprises a top cover on an end opposite the one end of the frame.

The top cover may protect the mechanisms and the chimney from external effects such precipitation. Alternatively, the top cover may protect vital parts of the chimney cap from birds looking to place their nests.

The sealing device may be provided with one or more stops, which project towards the top cover to engage with the top cover to prevent the sealing device from exiting the guiding assembly.

This increases reliability.

Preferably, the one or more guiding profiles extend beyond the first position of the sealing device and wherein the top cover is attached to the guiding profiles beyond the first position.

Accordingly the guiding profiles may serve as a structural component also, thereby reducing the number of parts needed in the frame.

It is possible for the guiding profiles to be equidistant. This leads to a more even distribution of forces throughout the guiding assembly, which in tum may lead to a smoother movement of the sealing device from the first position to the second position.

It is advantageous if the guiding profiles are slotted along their length, in order to prevent deposit buildup. In general, deposits are more likely to build up as the amount of material around the chimney increases. In the case of the guide profiles, deposits could block the sealing means from moving, so that for them in particular deposit prevention can be important.

In another embodiment of the invention, the chimney cap further comprises a mantle extending around at least the opening, the guiding assembly, the sealing device and the frame. This mantle may act as a protection from external effects, and/or may act as a barrier to prevent animals, or debris from entering the chimney. The mantle may further reduce or prevent burning material entrained in flue gas from escaping.

In particular, the mantle can be manufactured from sheet metal and/or the mantle can be a single integrally formed part. A corresponding design may facilitate manufacturing and/or durability.

In particular, the mantle can be provided with apertures. These will allow the flue gas to escape the chimney cap.

An alternative, mantle structure can be achieved by using a mesh. The mantle made of mesh has the further advantage that it includes relatively little material, which results in less deposits to build up due to condensation. Of course the mesh is particularly advantageous if the hole size as compared to the wire size of the mesh is sufficiently large, for instance 5 times larger.

To further reduce discourage deposit build up, the mesh extends relatively far down, even beyond its attachment point at the frame. This could of course also be done with the plate mantle.

The mesh extending down further removes the bottom of the caps exterior from the outlet of the chimney. In particular, a bottom plate is moved further away, thereby reducing its effect on deposit buildup.

A bottom plate may be provided, preferably extending outwards to beyond the mantle, to move water away from the chimney, also to discourage deposit formation. The bottom plate may have means for promoting water to detach / drip from the plate, for instance via an downward pointing edge. The bottom plate may be slanted.

The mantle, whether or not it is the mesh mantle, may include an inner mantle to locally reduce wind at the outlet of the chimney. It is advantageous if the inner mantle ends at a distance from the bottom plate, so that water may still exit beneath the inner mantle.

The top plate (i.e. the top cover), which preferably also extends outwardly to beyond the mantle, may have similar means for promoting water to detach / drip from the plate.

The invention will be further elucidated with reference to the attached drawings, in which:

Figure 1A shows schematically a front view of a chimney cap placed on a chimney connected to a furnace;

Figure 1B shows schematically a front detail view of the chimney cap of figure 1A during a chimney fire;

Figure 2 shows schematically a perspective view of the chimney cap of figures 1A — 1B with a sealing device in the first position;

Figure 3 shows schematically a perspective view of the same chimney cap, but with the sealing device m the second position;

Figure 4 shows schematically a top view of the sealing device with release mechanism;

Figure 5 shows schematically a close-up front view of a fusible clasp:

Figures 6 and 7 show schematically the sealing device and release mechanism before and during a chimney fire respectively;

Figure 8 shows schematically a cross section of another chimney cap, in perspective view.

Throughout the figures. like elements will be referred to using like reference numerals. Like elements of different embodiments are referred to using reference numerals increased by hundred (100).

Figure 1A shows the chimney cap 1, which has been placed on a chimney 2. The chimney 2 forms a connection between a furnace 23 and the environment, allowing flue gases to be transported away from the furnace 23 through the chimney 2, which in this case consist of a flue pipe, and the chimney cap 1. The mantle 3 on the outside of the frame of the chimney cap 1 is visible, along with the apertures it has been provided with. On top of the chimney cap 1 a top cover 4 is placed, which in this case extends outwards from the diameter of the mantle 3. Figure 1B shows the chimney cap 1, this time during a chimney fire (indicated by flames).

Figure 2 gives a more detailed view of the components of the chimney cap 1. Both the mantle 3 and the top cover 4 have been depicted transparently to enable viewing of interior components. The sealing device 5 has been placed in the first position, at the top of guiding profiles 9,10 together defining a guiding assembly. According to the current disclosure, the guiding assembly is placed radially outside the opening for the chimney 2. In this case, the sealing device 5 is a plate, made of sheet metal. The sealing device 5 is located in between the guiding assembly. It is noted that the guiding assembly extends along a projection of the opening of the chimney, thereby running along it but staying radially outside. Located on top of the sealing device 5 is the release mechanism 6. Sliding members 7 are placed on top, and have their degrees of freedom restricted by several guiding screws 8 which cooperate with slots in the sliding members 8. The sliding members 8 form a locking mechanism as described herein, because they either lock or release the sealing device 5 with respect to the guiding assembly. Furthermore, they are connected to a wall of the sealing device 5 by use of a bias member 12 for each sliding member 8, in this case a tensile spring. The sealing device 5 is slid into a recess 13 in the guiding profiles 9. The recess tapers in a direction away from the sliding member, i.e. it becomes narrower in that direction.

Guiding profiles 9, 10 are connected to the top cover 4 through the use of a hole 19 in which a bolt can be placed, and to the chimney 2 through a similar hole 20, and finally to the frame 50 with yet another similar hole 21. Finally, a shield 11 is visible, which is placed between the fusible clasp 13, which is not shown in this figure, and the chimney 2, to protect it from the heat when a chimney fire is not currently occurring.

Figure 3 once again shows the chimney cap 1, this time with the sealing device 5 in the second position, where it seals the outlet of the chimney 2. Compared to figure 2, the sealing device 5 has moved along the guiding profiles 9,10, after the release mechanism 6 released the sealing device from the recess 13 in the guiding profiles 9. The fusible clasp 15, which is not shown in the figure, has melted, thus allowing the movement of the sliding members 7 inwards and out of engagement with the guiding assembly, thereby unlocking the sealing device 5. The bias members 12 thus pulled the sliding members 7 towards the guiding profiles 9 closest to the respective bias member 12, thereby removing the protrusion of the sliding member 7 that was previously slid in the recess 13 from said recess 13, allowing the sealing device 5 to move down the guiding assembly.

Figure 4 shows the release mechanism 6 from the top down. Aside from the previously discussed parts, a part of the fusible clasp 15 is now visible in the middle of the sealing device 3, where it is connected to the sliding members 7 by protrusions of the sliding members 7, that travel through a hole in the sealing device 5. Finally, at the locations the sealing device 5 engages the guiding profiles 9,10, a protrusion 17 on the sealing device 5 has been bent perpendicular to the main plane of the scaling device 5, for the sealing device 5 to better fit in the guiding profile 9,10 and thus provide smoother movement. The fusible clasp 15 thus cooperates with the tensile springs 12 to create an actuation mechanism, which triggers when there is a chimney fire. Of course, a deformable clasp could be used instead of the fusible clasp 15, or some other type of heat-activated mechanism. Now referring to figure 5, the protrusions 14 on the sliding members can be seen from the side, with the fusible clasp 15 locking their movement. Behind them, the shield 11 can be seen, which hangs from the sealing device 3, and is bent so it forms a wall below the fusible clasp 15.

Figures 6 and 7 show the sealing device from the underside. A protrusion 16 from the bottom of the sealing device 5 can be noticed. This can either be a separate plate, or be part of the same piece of material that the original sealing device was manufactured with. The protrusion 16 has a diameter equal to the inner diameter of the chimney 2 the chimney cap 1 will be placed upon, thus creating the desired seal. In figure 7, a chimney fire is occurring, and thus the fusible clasp 15 has melted.

Figures 8 shows a chimney cap 101, which differs from the previously described chimney cap | in some aspects, but is otherwise the same. In particular, it has a mesh mantle 103. The mesh mantle 103 extends downwards further than its attachment point to the chimney 192 at frame 150.

Surrounding the opening of the chimney 192 is an inner mantle 194, which protects against e.g. wind and rain. The inner mantle 194 ends at a distance from a bottom plate 196, leave a space 193 open for water to flow outwards. The bottom plate 196 serves to move water away from the chimney 192, and may for this purpose (although not shown) even by slanted downwards. At its free end, the bottom plate 196 comprises a downward pointing edge 195 to promote water to drip off. A similar structure can be seen with the upper plate 104, which in the shown chimney cap 101 extends further outward than the previously shown upper plate 4. A similar drip promoting edge 199 is provided. Further, the sealing device 5 is provided with stoppers 197 on its top side, which can engage the top plate 104 and prevent the sealing device to move out of its guides 109. The sealing device 105 comprises flat ends 198 for engagement with the guides 109. Although not shown, the sealing device 105 comprises a stopper 197 for each of four guides, and similar flat ends 198 for each guide.

The present invention is not limited to the embodiment shown, but extends also to other embodiments falling within the scope of the appended claims.

Claims (22)

Conclusions 1. A chimney cap (10) for extinguishing a chimney fire, the chimney cap (10) comprising: - a frame (11) adapted to be installed on a chimney, the frame (11) defining an opening (12) at an end (13) of the frame (11), the opening (12) adapted to receive a flue from the chimney and defining an opening axis perpendicular to the opening, - a guide assembly (15) fixed to the frame (11), and - a sealing device (20) movable along the guide assembly (15) relative to the frame (11) between a first position (21) and a second position (22), wherein in the first position (21) the sealing device (20) is at a relatively large distance from the opening (12), thereby allowing flue gas to exit the flue through the chimney cap (10), and wherein in the second position (22) the sealing device (20) is at a relatively small distance from the opening (12), thus at least partially closing off the flue by abutting against it, characterised in that the guide assembly (15) leaves the opening (12) clear. 2. Chimney cowl (10) according to the preceding claim, wherein the guide assembly (15) is arranged radially outside the opening (12). A chimney cowl (10) as claimed in the preceding claim, wherein the guide assembly (13) is disposed radially outwardly of a space defined by a projection of the opening (12) along the opening axis, preferably towards an end of the chimney cowl (10) opposite the one end (13) and/or away from that opposite end beyond the one end (13). A chimney cowl (10) according to any preceding claim, further comprising a release mechanism (25), the release mechanism comprising: - a locking mechanism movable between a locking position, locking the sealing device (20) relative to the guide assembly (13), and an unlocking position, freely movable the sealing device (20) relative to the guide assembly (15); and - a drive mechanism adapted to drive the locking mechanism from the locking position to the unlocking position in the event of a chimney fire. A chimney cowl (10) as claimed in the preceding claim, wherein the actuating mechanism comprises: - at least one biasing member biasing the locking mechanism towards the unlocking position; and - a fusible fastener (26) holding the locking mechanism in the locked position, the fusible fastener (26) being adapted to fail by melting or softening when exposed to elevated temperatures encountered during a chimney fire, thereby releasing the locking mechanism; and/or - a heat-formable fastener (27) holding the locking mechanism in the locked position, the heat-formable fastener (27) being adapted to deform when exposed to elevated temperatures encountered during a chimney fire, thereby releasing the locking mechanism. 6. A chimney cowl (10) as claimed in the preceding claim, wherein the fusible closure or the heat-deformable closure is arranged on a side of the sealing device which faces the opening. A chimney cowl (10) as claimed in any one of claims 5 to 6, further comprising a shield (23) disposed between the fusible or heat-formable closure (26, 27) and the opening (12). 8. Chimney cowl (10) according to any one of claims 5 to 7, for example with the fusible closure, wherein the drive mechanism is arranged so that a pre-tensioning force of the pre-tensioning member acts as a tensile force on the closure (26). Chimney cowl (10) according to any of claims 4 to 8, wherein the sealing device (20) carries the release mechanism (25). A chimney cowl (10) as claimed in any one of claims 4 to 9, wherein the locking mechanism is located on a side of the sealing device (20) facing away from the opening, further or alternatively the biasing means, if provided, being provided on that side. Chimney cowl (10) according to any of claims 4 to 10, wherein the locking mechanism comprises at least one slide member (28) which, in the locking position, engages the guide assembly (15) to lock the sealing device (20). Chimney cowl (10) according to the preceding claim, wherein the at least one slide member (28) comprises a flat main body (41) and at least one reinforcing rib (42). A chimney cowl (10) as claimed in any one of claims 11 to 12, wherein the guide assembly (15) defines a recess (16) for receiving the at least one slide member (28), the recess (16) tapering in a direction away from the slide member (28). A chimney cowl (10) as claimed in any preceding claim, wherein the sealing device (20) has a larger cross-sectional area than the opening (12) when viewed from perpendicular to the opening axis. A chimney cowl (10) as claimed in the preceding claim, wherein the sealing device (20) comprises on a side facing the opening (12) a projection extending circumferentially at a distance radially inward from a periphery of the sealing device (20). 16. Chimney cap (10) according to any one of the preceding claims, wherein the guide assembly (15) comprises one or more, preferably four, guide profiles (17) positioned around the chimney, the guide profiles (17) extending substantially parallel to the opening axis. A chimney cowl (10) as claimed in any preceding claim further comprising a top cover (30) at an end opposite the one end (13) of the frame (11). Chimney cowl (10) according to the preceding claim, wherein the one or more guide profiles (17) extend beyond the first position (21) of the sealing device, and wherein the top cover (30) is arranged beyond the first position (21) on the accompanying profiles (17). Chimney cowl (10) according to any of claims 17 to 18, wherein the guide profiles (17) have an equal mutual spacing. A chimney cowl (10) as claimed in any preceding claim further comprising a skirt (32) extending around at least the opening (12), the guide assembly (15), the sealing device (20) and the frame (11). 21. A chimney cowl (10) as claimed in the preceding claim, wherein the casing (32) is made of sheet metal and/or wherein the casing (32) is a single, integrally formed part. 22. Chimney cowl (10) according to the preceding claim, wherein the casing (32) is provided with holes.