GB2236170A - Control of air flow through a flue - Google Patents

Abstract

A device for controlling air flow through a flue, such as a chimney flue, 7, comprises an inflatable bladder 1 of a flexible material, adapted when in its deflated state to be inserted into a flue and thereafter, in use, inflated into its inflated state so as to sit in substantially sealing manner within the flue and thereby control the flow of air. The bladder may also include passages 4 (with closures 5) by which, when it is inflated, a reduced flow of air can pass from side to side of the bladder within the flue. An inlet valve 2 and pressure relief valve 3 are provided. <IMAGE>

Description

Title: Control of Air Flow through a Flue Field of the invention This invention relates to the control of air flow through a flue, and has particular, but not exclusive, application to reduction of air flow through a chimney flue in the case where an open fire below the chimney flue is not in use.

Background to the invention Many buildings. both old and new, have open fireplaces with chimneys for directing smoke and fumes from the fire tn the outside of the building. When an open fire is not in use draughts, caused by the flow of air through the chirtiney flue, may arise, possibly causing problems. Not nrllv can heat be lost from the building by the flow of t..rou~h the flue to the outside, but also, particularly nn windy days, a downwards current of air can bring soot, with its associated dirt and odour, into the building from inside the flue. Rain can also enter the building through an open chimney.

Various methods, most of which involve blocking off the chimney flue to the outside air or restricting air flow through the flue in some way, are currently known for alleviating this problem. One such method involves the fitting of a cowl to the top of the flue. This can be a costly process and generally has to be performed by an expert. Prevention of down-draughts is not always reliably achieved; nor do cowls inhibit heat loss through the flue to any material extent.

Another currently used method involves "capping" a chimney flue by placing a metal plate across its top. This can also be expensive, and again the cap generally needs to be fitted by an expert. This approach also results in the flue being permanently blocked and hence prevents further use of the open fire, whereas in many cases only a temporary solution to the draught problem is needed. For instance, an open fire might be used regularly in the winter but less so in the summer, and temporary protection from undesired air flow through the chimney flue would only be needed during the summer months of the year.

A third method, often used to reduce draughts through a chimney flue, is to block the flue with items such as pillows, blankets, newspapers and the like. this is clearly unsatisfactory, not only because the articles used to block the flue can frequently become dislodged, but also because the method can result in insufficient ventilation of the flue.

It is an aim of the present invention to provide a device and method for the temporary control of air flow through a flue, involving apparatus which is relatively easy to install in, and remove from, the flue and which can therefore be used as a solution to the problems associated with undesired air flow through the flue.

Summary of the invention According to one aspect of the present invention there is provided a device for controlling air flow through a flue, comprising an inflatable bladder of flexible material, the bladder being inflatable and deflatable between a deflated and an inflated state, with means being provided for maintaining the bladder in its inflated state, the bladder being adapted when in its deflated state to be inserted into a flue and thereafter, in use, inflated into its inflated state so as to sit in substantially sealing manner within the flue and thereby control the flow of air through the flue.

Such a device can easily be inserted, in its deflated state, into a flue, particularly a chimney flue over an open fire, and there inflated so as to remain positioned inside the flue. Typically the device would be instailed a short distance above the inner end of the flue, So as to be readily accessible. The device can also be easily removed, say when the user wishes to use an open fire below, by deflation and removal of the bladder. The device can thus be temporarily installed by the user himself and represents a relatively cheap solution to problems associated with unwanted or excessive air flow through a flue.

The bladder may be made of any suitable impermeable, flexible material, which is preferably capable of being inflated and of remaining in its inflated state for extended periods of time. Both natural rubber and butyl rubber are suitable materials, although natural rubber is the preferred material since it is mechanically strong resistant to puncture, either by sharp objects or through wear. Since the device of the present invention will probably have to withstand repeated inflation and deflation, it is preferable that the material from which it is made is resistant to such wear.

The dimensions and shape of the bladder may vary according to the dimensions and shape of the particular flue in which the device is intended to be used, and a range of bladders of different sizes and shapes may be produced for use in different flue types.

The bladder is preferably between 3 and 4 inches in height when in use in its inflated state inside a flue.

The bladder may be inflatable by any standard means, such as a foot pump or any other pump. The bladder conveniently has an inlet valve such as is found on the inner tube of a car tyre or alternatively the inner tube of a bicycle tyre, through which the bladder can be inflated, and is preferably inflated with air, although any other fluid such as water or an inert gas may alternatively be used.

The bladder preferably additionally comprises a pressure release valve so as to prevent over-inflation. If the bladder is inflated to too high a pressure inside a flue, its outer edges may be pressed too firmly against the inner walls of the flue, and since these inner walls are quite often rough and may incorporate sharp edges or other protruding objects, pressing the bladder too tightly against the walls may result in its puncture.

It is desirable that not all of the air flow through the flue is cut off when the device of the present invention is in use. Rather, a controlled but reduced flow of air is required through the flue between the building and the outside, in order to prevent the build up of damp or stale air inside the flue. In order to achieve such a controlled flow of air, the bladder conveniently includes passage means by which, when the bladder is positioned in its inflated state in a flue, a reduced flow of air inside the flue can pass between the region above the bladder and the region below the bladder.

The passage means will typically comprise one or more passages running through the bladder and communicating, when the bladder is in use, between regions of the flue above and below the bladder.

Each such passage is conveniently closeable at its lower end in use. Each passage may, for instance, be provided with a stopper which can be removably inserted into an end of the passage to close or open the passage as desired.

Thus, the user can select the number of passages which are required to be open and hence can control the flow of air through the flue and the bladder positioned in it.

In a further aspect the invention provides a method of controlling air flow through a flue, comprising inserting into the flue a device in accordance with the invention and inflating the device so as to sit in substantially sealing manner within the flue.

One embodiment of a device of the present invention will now be described, by way of illustration only, with reference to the accompanying drawings.

Brief description of the drawings Figure 1 shows a schematic section through a device in accordance with the present invention; Figure 2 is a plan view of the device of Figure 1; and Figure 3 is a schematic section through a chimney flue, showing the device of Figure 1 in use.

Detailed description The device shown in Figures 1 and 2 comprises an inflatable bladder 1 of generally rectangular configuration, made of natural or butyl rubber (shown in the figures in an inflated state). The bladder includes an inlet valve 2 which is similar to an inlet valve on rne inner tube of a car tyre or bicycle tyre, and which enables the bladder to be inflated with air or another suitable fluid, eg by use of a standard foot pump. Oneway pressure-release valve 3 ensures that the bladder is not over-inflated and hence, in use, does not press too firmly against the inner walls of a chimney flue.

The bladder additionally comprises three passages 4, extending through the bladder. When the device is in use inside a flue, each passage communicates with flue regions above and below the device. Each passage 4 is provided with a releaseable stopper 5 at its lower end, thus enabling the user to open or close any of the three passages according to requirements.

The device of Figure 1 can be inserted into a flue in its deflated state and then held in position at a suitable location inside the flue, and inflated to its inflated state. In this state, the device sits in position in the flue, with its outer edges flush with the inner walls of the flue.

Figure 3 shows the device in such a position inside a chimney flue 7, above an open fireplace 6.

The bladder is inflated so as to press against the inner walls of the flue just firmly enough to hold the device in position. The device thus forms a block across the flue, substantially preventing the passage of air from the inside of the building, through the open fire place 6 and the flue 7 to the outside, or vice versa.

The device 1 is positioned in the flue 7 with passages 4 running substantially vertically, these passages allowing for a certain amount of air to pass through the device from the region below to the region above it, or vice versa. Thus a small and controlled flow of air through the flue is achieved, in order to ventilate the flue and prevent damp. The extent of the flow is controllable by the user by means of stoppers 5 to open or close passagcs 4.

when the user wishes to light a fire in the open fire place 6 below the flue, the device 1 is simply deflated by opening inlet valve 2, and the bladder can then be easily removed, in its deflated state, from inside the flue.

The device, when in use, not only prevents draughts through the flue, but also provides a measure of insulation, reducing heat flow from the inside of the building to the outside.

The device of Figure 1 is of such dimensions and shape as to fit snugly inside the chimney flue 7 shown in Figure 3.

However, a device in accordance with the present invention could be made to be inflatable to any desired size and shape.

Such a device may be used in its fully inflated state, or in an inflated state intermediate between its fully inflated and fully deflated states. Thus the same device may be inflated to fit inside a range of different sizes of flue.

The device of Figure 1 is clearly easy to use and, because of the simplicity of its design, and the material from which it is made, will be relatively inexpensive to produce. It is also portable and easy to store, being in its deflated state small, light and compact.

Claims (14)

1. A device for controlling air flow through a flue, comprising an inflatable bladder of flexible material, the bladder being inflatable and deflatable between a deflated and an inflated state, with means being provided for maintaining the bladder in its inflated state, the bladder being adapted when in its deflated state to be inserted into a flue and thereafter, in use, inflated into its inflated state so as to sit in substantially sealing manner within the flue and thereby control the flow of air through the flue.

2. A device according to Claim 1, wherein the bladder is made of an impermeable, flexible material, and is capable of being inflated and of remaining in its inflated state for extended periods of time.

3. A device according to Claim 1 or Claim 2, wherein the bladder is made of natural rubber.

4. A device according to Claim 1 or Claim 2, wherein the bladder is made of butyl rubber.

5. A device according to any one ot the preceaing claims, wherein the bladder is between 76 and 102mm (3 and 4 inches) in height when in use in its inflated state inside a flue.

6. A device according to any one of the preceding claims, wherein the bladder has an inlet valve through which the bladder can be inflated.

7. A device according to any one of the preceding claims, wherein the bladder additionally comprises a pressure release valve so as to prevent over-inflation of the bladder.

8. A device according to any one of the preceding claims, wherein the bladder includes passage means by which, when the bladder is positioned in its inflated state inside a flue, a reduced flow of air inside the flue can pass between the region above the bladder and the region below the bladder.

9. A device according to Claim 8, wherein the passage means comprises one or more passages running through the bladder and communicating, when the bladder is in use, between regions of the flue above and below the bladder.

10. A device according to Claim 9, wherein one or more of the passages is closeable at its lower end in use.

11. A device according to Claim 9 or Claim 10, wherein one or more of the passages is provided with a respective stopper which can be removably inserted into an end of the passage to close or open the passage as desired.

12. A device for controlling air flow through a flue substantially as herein described with reference to, and as shown in, the accompanying drawings.

13. A method of controlling air flow through a flue, comprising inserting into the flue a device according to any one of the preceding claims and inflating the device so as to sit in substantially sealing manner within the flue.

14. A method according to Claim 13, wherein the device is inflated with air.