GB2544784A

GB2544784A - A Chimney cowl

Info

Publication number: GB2544784A
Application number: GB1520913.3A
Authority: GB
Inventors: Byrne Gearoid
Original assignee: Design IQ Ltd
Current assignee: Design IQ Ltd
Priority date: 2015-11-26
Filing date: 2015-11-26
Publication date: 2017-05-31
Also published as: GB201520913D0

Abstract

A chimney cowl arrangement comprising a base portion 20 to be inserted into a chimney 4, the base portion including plural barbs or teeth 10 to engage with the inner surface of the chimney to hold the cowl in position. Preferably the barbs are mounted on a ring 8a, 8b around the base portion. There are preferably two sets of barbs, a first 8b located at the base of the base portion and a second 8a located upward of the first ring.

Description

Title A chimney cowl Field

The present application relates to chimney cowls and in particular to methods of securing them to a chimney.

Background Of The Invention

Chimney cowls also known as chimney terminals are provided on the top of chimneys for a number of purposes including for example: a to solve “draught” problems; b stop debris or rain entering the chimney; c prevent birds or other animals nesting;

The termination of some chimneys utilise the continuation of the chimney liner through the brickwork capping onto which a cowl/terminal can usually be easily fitted. However, for architectural reasons it is common practice to use a chimney pot to finish off the top of a chimney.

There are currently a number of different approaches to fixing a cowl to a chimney pot including: a) Clamp Cowl. In this arrangement, 4 adjustable hook bolts are employed to engage on the inner face of the chimney pot. The bolts are tightened by wing nuts from the outside of the cowl. This arrangement suffers from a number of problems including that they can loosen in strong winds or overtightening can crack the chimney pot. b) Sleeve Cowl. In this arrangement, an expanding sleeve engages the internal circumference of the chimney pot. These however tend to be expensive and difficult to centre on the chimney pot. c) Strap Cowl. In this arrangement which is the most commonly employed design, a series of legs from the cowl are fixed by a strap which is tightened around the circumference of the chimney pot.

The strap cowl is by far the most commonly employed as it is reliable, inexpensive and easy to fix. At the same time, the use of the strap spreads the load around the circumference of the chimney pot and thus reduces the risk of cracking the chimney pot.

Unfortunately, the strap cowl is not suitable for all chimney pots depending on their profiles. Some examples of chimney pot profiles 4a-d and their suitability/unsuitability for use a strap cowl 2 are illustrated in figure 1. Each representation a - d illustrates a cowl 2, the chimney pot 4a-4d and then an assembly where possible of the cowl on a chimney pot in a chimney stack 6.

The first chimney pot 4a represents the one which works best when fixing a cowl and the suitability decreases from left to right, with the fourth chimney pot 4d representing a situation where a cowl cannot be fixed.

The present application is directing at providing an alternative fixing method to fix a cowl to a chimney pot.

Summary

The present application provides a cowl which avoids the problems of the prior art by using resilient engaging features on a base section of a cowl to engage with the inner surface of a chimney pot rather than the conventional approaches of fixing to the outside of a chimney pot. The resilient engaging features are designed to allow the base section be slid into the chimney whilst at the same preventing the cowl from being withdrawn (e.g. by force of the wind.

Brief Description Of The Drawings

The present application will now be described with reference to the accompanying drawings in which:

Figure 1 illustrates different types of chimney pot and their suitability for installing a prior art strap cowl thereon;

Figure 2 is a side profile view of a chimney pot in which is inserted a base portion of a chimney cowl according to a first aspect of the present application;

Figure 3 is a view of a strip with engaging features employed with the first aspect shown in Figure 2;

Figure 4 is a end view of the strip of Figure 3;

Figure 5 is a perspective view of a strip of the type shown in Figures 3 and 4 formed into a circular form;

Figure 6 is a side view of the circular arrangement of Figure 5;

Figure 7 is a base portion of a cowl including an insertion limiting feature; Figure 8 is a base portion of a cowl as shown in Figure 7 with a top section shaped to limit downdraft;

Figure 9 are examples of exemplary cowls with a bottom section as shown in figure 7 and various top sections shaped to a prevent bird ingress, b provide a H shaped cowl, c to prevent rain ingress a capping cowl;

Figure 10 illustrates two examples of how the barbed strips may be employed on cowls for use with non-cylindrical shaped chimneys, e.g. square shaped chimneys;

Figure 11 is a perspective view of a chimney with a cutaway illustrating how when a cowl is inserted it resists the wind; and

Figure 12 is an example of how the cowl may be used with a chimney.

Detailed Description Of The Drawings

The present application solves the problems of the prior art by providing a cowl that is designed to be inserted into and to substantially match with and thus fit within the interior wall of a chimney pot. As the interior profiles of chimney pots tend to have a uniform shape for example constant diameter, the difficulties of accommodating different external profiles is overcome.

At the same time, the solution provided is easy to install, inexpensive to manufacture, resistant to wind and not prone to damaging the pot in which it might be installed.

As shown, in Figure 2, an exemplary cowl of the present application comprises a base portion 20 having a generally cylindrical body. The cylindrical body has a leading edge 22 which is dimensioned to be insertable into the opening of a chimney pot 4.

The external diameter of the cylindrical body is selected to be less than the internal diameter of the chimney pot to allow the cylindrical body to be slidably inserted into the chimney pot 4. At the same time, the external diameter is selected to be sufficiently large so that there is limited movement possible between the cowl and the internal wall of the chimney pot. In this respect, suitably the external diameter of the cowl is approximately within 10mm or less of the internal diameter of the chimney pot.

It will be appreciated that different cowls, or at least different base portions, may be provided for different diameters of chimney pot.

The cylindrical body suitably has one or more engaging features provided around its circumference to fix the cowl in place so as to prevent wind lifting the cowl from the chimney pot.

In the arrangement shown, the engaging features comprise at least one arrangement of barbs, 8a, 8b, provided around the base portion 20 of the chimney cowl 2 in a crown like fashion.

The crown comprises a strip 8 of material, suitably a metal, which may be fixed to the outer cylindrical surface of the base. The strip may be of sufficient length to encircle the base portion or alternatively several strips may be separately affixed around the cowl possibly with gaps there between. The strip comprises a planar main section 18. The planar main section has a longitudinal axis and the barbs 10 extend from one side of the main section in a direction transverse to the longitudinal axis. At the same time, the barbs are angled away from the plane of the planar main section.

The strips may be fixed by a fastening method, for example, welding soldering or adhesive. Mechanical fastenings may also be used, for example rivets or fixing tabs with co-operating slots in the cowl.

When fixed on the base portion of a cowl, the barbs extend from the strip or strips in a crown like configuration in a generally upwards direction, i.e. away from the leading edge of the base portion. The barbs are formed to be resilient. Thus as a cowl is inserted into a chimney, the barbs when forced against the wall of the chimney pot flex toward the cowl allowing the cowl to be inserted. However, once inserted into a chimney pot, the ends of the barbs engage with the surface of the chimney pot prevent the removal of the cowl. To assist with this the end profile of each barb may be shaped to define an edge rather than a point. In this arrangement, the edge is suitably aligned with the longitudinal axis of the strip. While points may be used, greater strength is obtained by using the wider profile of the edge.

The base portion of the chimney cowl is shaped so as to be insertable into a corresponding chimney pot 4. However, it desirable that there be a limit to the extent to which the cowl may be inserted. In this respect, a flange, bead, rim 40 or other insertion limiting feature such a protruding series of raised bumps, bolts etc may be provided on the outer surface of the base portion to limit the insertion of the cowl into the chimney pot. The insertion limiting feature is suitably provided on the opposite side of the crown to the leading edge of the cowl base. For obvious reasons, the outer diameter of the insertion limiting feature is suitably larger than the internal diameter of the chimney pot into which the cowl is being inserted.

The crown of barbs is provided around the circumference of the outer surface of the cowl between the leading edge and the insertion limiting feature. Each of the barbs 10 is configured to engage with the inner surface of a chimney pot 4 as the cowl 2 is inserted into the chimney pot 4 so as to provide a force prevent the removal of the cowl. The barbs suitably extend linearly from the cowl to the chimney 6. Alternatively, they barbs may be curved slightly toward the chimney. Desirably, the barbs are not curved back toward the cowl as this would present a smooth rounded surface to the chimney pot, which would not engage the interior surface of the chimney pot to retain the pot in place unless significant resilient force was employed, which might lead to cracking of the chimney pot. The barbs are suitably formed from a resilient material so that they are sprung. In this way, the barbs have a relaxed state in which they have an angle with respect to the cowl. The outer circumference of the crown of barbs in this relaxed state is selected to be higher than the inner circumference of the chimney pot into which the cowl is to be inserted. As the cowl 2 is inserted into the chimney pot 4, the crown of barbs 8 is compressed to a compressed state. The resilient nature of the barb material is such however that the barbs react against this compression providing a corresponding expansive force.

The crown 8 may be formed as a single strip which is provided around the outer surface of the chimney cowl 2. The strip may be fixed by any suitable fixing method, including for example, welding, soldering, adhesive or rivets.

In an alternative construction, the barbs 10 are integrally formed in the cowl for example by stamping out their profile in the outer surface of the cowl.

Whilst a single crown of barbs may be sufficient, it is preferable to employ more than one crown. In this arrangement, the multiple crowns are spaced apart from each other along the base portion with a first crown nearer to the leading edge and the second crown nearer to the insertion limiting feature. One or more intermediate crowns may be positioned between the first and second crowns. As an example, Figures 2, 7, 8, 9 and 11 all show two crowns 8a, 8b present on the base portion of a cylindrical cowl.

Using the first and second crowns 8a, 8b provides for a more secure fit and limits lateral skewing movement, for example, by wind that might happen if just one crown was employed, for example close to the insertion edge.

It will be appreciated that the barbs 10 need to engage with the internal surface of the chimney pot 4 to prevent movement. Accordingly, the barbs are selected to provide a relatively sharp engaging end 30. This need be nothing more than the leading edge of the barb. However, it clearly cannot be anything that presents a smooth or low friction engagement with the chimney pot, for example a curved end profile where the leading edge curves back towards the cowl. Such a curved surface would allow for the cowl to be easily inserted and removed since the friction would be the same when inserting the cowl into the chimney pot as when removing it.

In contrast, the purpose of the shape of the barbs is to present a larger frictional force in the direction of removal from a chimney pot than in the direction of insertion into a chimney pot.

Accordingly, a desirable feature of the present application is that each of the barbs 10 is configured to engage with the surface to prevent the withdrawal of the cowl. Alternatively stated, the individual barbs are shaped to allow insertion of the cowl 2 into a chimney pot 4 but to limit the withdrawal of the cowl from the chimney pot. Thus, ignoring the effects of gravity, it requires significantly more effort to overcome the frictional force, for example five times greater or more, to remove the cowl from the chimney than to insert the cowl into the chimney.

Whilst the crown 8 may be employed with a cowl 2 having a circular cross section for inserting into a corresponding circular cross section chimney pot 4, it will be appreciated that it may equally be employed with other shapes. Thus for example if the chimney pot has a generally rectangular, e.g. square, profile, it would require a correspondingly shaped cowl and in which case a rectangular shaped crown of barbs may be employed, as illustrated in the cowls 60a, 60b of Figure 10

In one example, the crown 8 is formed as a strip acting as a base 18 with an engaging portion of each barb 10 extending from the intersection 32 with the base 32 to an engaging edge 30. Suitably the engaging portion tapers along the sides 34 so that the width of the base end 32 is greater than that at the engaging edge 30. Thus in the exemplary arrangement shown, the width at the base end is 25mm with the width at the engaging end being 15mm. Suitably, the width of the engaging end is at least 40% that of the base end.

The width of the engaging portion at the base end is suitably equal to or greater than the length, shown in the example as 10mm, of the engaging portion from the base end to the engaging end. This ensures there is sufficient resilience in the barb 10. This resilience is improved further if the width of the engaging end is greater than the length of the engaging portion from the base end to the engaging end.

In the exemplary arrangement shown, the engaging ends are shown as a linear edge which is parallel to the strip base of the crown. The use of such an edge maximises the contact with the chimney. Other shapes for example sawtoothed profiles could be employed along the engaging edge.

Additionally, in the exemplary arrangement shown, there is a spacing provided between adjacent barbs. In the exemplary arrangement, the spacing is 5mm. Suitably, the spacing and tapering of the barbs is such that the combined length of the engaging surfaces along a strip are at least 50% of the strip length, and preferably greater than 70%.

The barbs 10 are pre-bent from the strip to a particular angle. This angle defines a relaxed state of the crown. Suitably, the angle is at least 15 degrees. Similarly, the angle is suitably less than 60 degrees. As a cowl 2 is inserted into a chimney, the chimney surface compresses the angle of the barbs. The resilient reaction of the barbs to this compression in combination with the sharp edge of the barbs prevents the cowl once inserted from being removed.

The crowns may be integrally formed with the cowl, i.e. the cowls are sold to the end user with the barbs pre-fitted. Alternatively, the crowns may be provided separately to the cowls. For example, the crowns may be provided in a roll form to an installer from which the installer can cut a section to generally match the outer circumference size of the cowl. Once cut, the section may then be fixed to the cowl by a suitable fixing method, e.g. adhesive, welding, soldering or a mechanical fixing such as a rivet, screw or nut and bolt. In this respect, the strip portion of the crown 8 may have pre-formed holes provided therein to facilitate fixing of the strip to the crown using a mechanical fixing. As an example, a fixing hole might be provided in the strip generally aligned with the centre of each barb. Alternatively, the crown 8 may be formed from a series of strips having a smaller length than the circumference of the cowl 2 and in which case they are arranged together to provide a crown around the cowl. It will be appreciated that the reference to crown is merely for illustration and it is not necessary that the entire circumference of the cowl be covered with barbs. Thus for example, where a series of strips are employed, there may be gaps between each of the adjacent strips. However, desirably the length of the gaps is limited as much as practical.

It will be appreciated that the optimal dimensions for the barbs 10 will depend on the choice of material for the barbs and cowl 10 and the material thickness. Suitably, the barbs and cowl material is a metal. In the context of its intended use, the metal selected needs to provide a degree of resilience and at the same time be suitable for use in the environment in question e.g. present a degree of resistance to corrosion. Thus one example of a suitable metal is a stainless steel. In the context of the present use, a thickness of at least ,2mm is desirable to ensure suitable resilience. At the same time, a thickness of less than 2mm is desirable to ensure that the resilient force is not too high that it would prevent reasonable insertion of the cowl 2 into the chimney pot.

The base portion may be used with a variety of different top sections depending on the type of cowl required in a particular application. In this respect, the top section and base portion may be provided as one integral piece or alternatively they may be fixed together as required. Thus different sized base portions may be provided to accommodate different chimney sizes with different top sections provided to provide different types of cowl which may be fixed to a required base section as appropriate prior to or during installation. Exemplary cowl types are thus shown in Figure 8 and 9.

The present application also provides a method of fixing a cowl using the previously discussed crown. The method comprises selecting a chimney cowl 2 having a base portion having an outer shape and size to be receivable in the chimney pot. The diameter of the cowl is suitably no more than 1 cm less than that of the inner diameter of the chimney pot 4. A least one row of resilient barbs 10 are provided around the outer surface of the base portion, for example of the type described above and finally the cowl is inserted in the chimney pot.

In this arrangement, each of the barbs is directed generally away from the leading end of the cowl so that when inserted in a chimney they are generally angled upward and toward the inner surface of the chimney pot.

It will be appreciated that the fixing method described in this application is such that excessive wind conditions can not disturb the mechanical grip demonstrated by the barbed crowns or strips 8. The horizontally aligned rectangular profile of each of the mechanically secured crowns or strips is such that any substantial sideways movement out of the vertical would be almost impossible under normal environmental conditions e.g. storm winds 80 as shown in Figure 11. Indeed it will be appreciated that were there any slight movement, it result in an increase of the “bite” or engagement of the barbs, making it very difficult for any wind induce pressure movement to loosen the hold or removal of the cowl 2 or terminal.

Additionally, it will be appreciated that the cowl arrangement described herein, may be used with chimney pots such as the exemplary pot 4d shown in Figure 1 as illustrated in Figure 12.

The words comprises/comprising when used in this specification are to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers , steps, components or groups thereof.

Claims

1. A chimney cowl comprising a body having a base portion having an outer surface shaped to be received within a chimney pot, the base portion having a leading end for inserting first into the chimney pot, the outer surface having provided thereon a plurality of resilient barbs which are configured to engage with the inner surface of a chimney pot as the cowl is inserted into the chimney pot so as to prevent the removal of the cowl.

2. A chimney cowl according to claim 1, wherein the resilient barbs are integrally formed in the base portion of the cowl.

3. A chimney cowl according to claim 1, wherein the resilient barbs are formed as one or more strips which are fixed to the base portion of the cowl.

4. A chimney cowl according to any preceding claim wherein an insertion limiting feature is provided at the opposite end of the base portion to the leading end to limit the progress of the cowl into the chimney.

5. A chimney cowl according to any preceding claim, wherein the plurality of resilient barbs comprises a first row of barbs arranged generally about the perimeter of the base portion.

6. A chimney cowl according to claim 5, further comprises a second row of barbs arranged generally about the perimeter of the base portion wherein the first and second rows are spaced apart along the length of the base portion.

7. A chimney cowl according to any preceding claim, wherein the cowl has a generally circular cross section.

8. A chimney cowl according to any one of claims 1 to 6, wherein the cowl has a generally rectangular cross section.

9. A chimney cowl according to any preceding claim, wherein each barb has a base affixed to the cowl with an engaging portion extending from the base to an engaging edge.

10. A chimney cowl according to any preceding claim, wherein the engaging edge is directed away from the cowl base and the leading end.

11. A chimney cowl according to any preceding claim, wherein the engaging edge is linear.

12. A chimney cowl according to any one of claims 1 to 10, wherein the engaging edge is tooth shaped.

13. A chimney cowl, according to any preceding claim, wherein the barb extends linearly from the barb base to the engaging edge.

14. A chimney cowl according to any preceding claim, wherein the angle of barb to the base relative to the center axis of the cowl prior to insertion in a chimney is less than 50 degrees.

15. A chimney cowl according to any preceding claim, wherein the angle of barb to the base relative to the center axis of the cowl prior to insertion in a chimney is at least 20 degrees.

16. A chimney cowl according to any preceding claim, wherein the angle of barb to the base relative to the center axis of the cowl after insertion is greater than 10 degrees.

17. A method of fixing a chimney cowl to a chimney pot, the method comprising the steps of: a) selecting a chimney cowl having a base portion having an outer shape and size to be receivable in the chimney pot and wherein the base portion comprises a leading end for inserting first into the chimney; b) providing at least one row of resilient barbs around the outer surface of the base portion, wherein each of the barbs is directed generally away from the outer surface and the leading end; and c) inserting the chimney cowl into the chimney pot.

18. A chimney cowl as described herein with reference to and/or as illustrated in accompanying figures 2 to 12.

19. A chimney cowl as described herein with reference to and/or as illustrated in accompanying figures 2 to 12.

20. A barbed crown for use with a cowl as described herein with reference to and/or as illustrated in accompanying figures 2 to 12.