GB2076514A

GB2076514A - Flue terminal

Info

Publication number: GB2076514A
Application number: GB8016351A
Authority: GB
Original assignee: TOWER FLUE COMPONENTS Ltd
Current assignee: TOWER FLUE COMPONENTS Ltd
Priority date: 1980-05-16
Filing date: 1980-05-16
Publication date: 1981-12-02

Abstract

A flue terminal comprising a single folded metal sheet forming a cylinder closed by an overlapping longitudinal edge join (19) and incorporating a continuous annular indentation (18) as a stiffening section in the flue terminal body at or adjacent one end for insertion in or attachment to the flue, the opposite end of the flue terminal body incorporating a series of part-annular vents (12) in the flue terminal wall and being fitted with an end cap (14) formed by a separate pressing with an overlapping rim (15) into which the main flue terminal body is received. <IMAGE>

Description

SPECIFICATION Flue terminal This invention relates to flue terminals and is particularly concerned with the terminal or endfitting for a chimney, flue or other gas flow duct or passage. Such a flue terminal enables gases etc., being vented from the flue, to emerge freely, whilst preventing the ingress of extraneous matter such as general debris (even birds) and rain, which might obstruct the flue and inhibit the egress of gas or vapour therefrom, possibly interfering with the combustion source or burner venting into the flue.

Owing to the importance of correct flue terminal design, particularly for gas burning appliances where correct combustion conditions and venting of noxious gases must be achieved for safety and efficiency of operation, fairly strict guidlines or criteria may be laid down by appropriate regulatory authorities, such as the British Gas Corporation, for the construction and dimensions of flue terminals, for example bent area in proportion to the flue duct cross-section.

The construction must also be durable enough to withstand exposure to severe weather conditions in the presence of moisture, wind and hot flue gases, without deteriorating, and specifically without deforming, leaking or corroding. Exposure to wind conditions requires that the flue terminal must be of inherently rigid construction and provided with means for securing fixing to the flue or flue liner.

Flues or flue liners of rigid or flexible walled metal construction have been used extensively and metal flue terminals of complementary construction are a commonly preferred means of capping or ending the flue. Typically such metal construction has employed an assembly of several separate parts of stamped, pressed orfolded metal sheets to form the flue terminal top or head of desired shape, typically a cylinder, which is punched with the necessary vent apertures and provided with separately fabricated end cap mounted transversely to the duct axis and across the pipe cross-section, so that gases vent from the side of the terminal rather than the end.

Another cylindrical neck section, typically of smaller cross-section for securing to the flue wall is similarly fabricated from several parts, but without vents, and is secured to the head assembly.

Fabrication from several sheet metal parts in this way is time-consuming and expensive on a mass production scale and the manner of assembly can result in a multiplicity of exposed overlapping edges, which may allow the uncontrolled egress of noxious vapour and the ingress of water, imparing the performance of the flue terminal and accelerating the onset of corrosion. Similarly the manner of fastening of overlapping, adjoining or abutting edges of the metal sheet may require the laborious multiple drilling and riveting process.

It is also an architectural requirement that the flue terminal design be of acceptably unobtrusive appearance, whilst retaining the operational effectiveness referred to above.

It is an object of the invention to provide a simplified flue terminal construction.

According to one aspect of the invention a method of fabricating a flue terminal comprises the steps of folding a metal sheet round a former into a cylindrical flue duct shape of generally uniform cross-section, joining along the longitudinal edges parallel to the duct axis and forming an annular indentation in the wall of the flue body to act as a stiffening rib.

A separately fabricated end cap is subsequently attached to the flue terminal body formed in this manner.

Punching or stamping of the vents in the flue terminal wall may be achieved before folding the single metal sheet forming the entire flue terminal body.

The stiffening rib thus lies between one 'neck' end of the terminal for connection to a flue and the opposite end to receive an end cap and vents in the wall thereof.

According to another aspect of the invention a flue terminal comprises a single folded metal sheet forming a cylinder closed by an overlapping longitudinal edge join and incorporating a continuous annular indentation as a stiffening section in the flue body at or adjacent one end for insertion in or attachment to the flue, the opposite end of the flue terminal body incorporating a series of part-annular vents in the flue terminal wall and being fitted with an end cap formed by a separate pressing with an overlapping rim into which the main flue terminal body is received.

Preferably, the flue terminal is of generally uniform cross-section.

Desirably, the longitudinal overlapping edge join of the flue terminal body and the rim of the end cap are secured by riveting. Alternatively, these joins can be secured by other means, such as welding or brazing or forming one or more locking indentations through the overlapping layers.

There now follows a description of a particular embodiment of the invention, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a perspective view of a flue terminal; Figure 2 shows an upper plan view of the flue terminal shown in Figure 1; Figure 3 shows an underside plan view of the flue terminal shown in Figures 1 and 2; Figure 4 shows a side elevation of the flue terminal shown in Figures 1 to 3; and Figure 5 shows a section along line 5-5 in Figure 2.

Referring to the drawings, a flue terminal comprises a generally cylindrical body 10 formed by folding a single metal sheet around a former and joining the opposed overlapping edges along a single longitudinal join 19, as shown only in Figure 1. Rivets, not shown, or other fastening means may be used to s'ecure this join.

The body 10 is closed at one end by and end cap 14. The latter has an overlapping rim 15 by which the end cap 14 is secured firmly to the end lip of the flue terminal body. A suitable fastening means may be employed for this purpose, but as an example a rivet 16 is shown in Figures 1 and 2 - and a series of such rivets spaced around the circumference of the rim 15 may be employed.

A series of rows of part-annular vents 12 in the terminal body circumference are formed by special stamp or punch tooling which cuts out three sides of each individual vent opening to form a flat joined to the vent body wall along one long edge and this flap is subsequently deformed slightly to form a louvre type opening. An adjacent series of such vents are simultaneously formed to achieve an overall louvred effect, which will deflect draughts which would otherwise blow directly into the flue terminal, producing a downdraught into the flue affecting the combustion device or burner venting into the flue and possibly pushing noxious gases and or smoke and fumes back into the area of the burner.

At the same time, the louvred vent configuration allows the free egress of vapours from the flue.

The terminal cap 14 prevents the direct ingress of large objects such as birds and smaller debris, falling rain or moisture, which might accumulate in or obstruct the flue and or fall down and affect the operation of the combustion device or burner venting into the flue.

The annular indentation 18 forms a stiffening rib in the overall flue terminal body to maintain overall rigidity and strength, in particular to inhibit deformation of the flue terminal body wall when fitted on the end of the flue. Mounting of the flue terminal may either be by inserting the end of the metal flue or flue liner into the mouth of the flue terminal up to the annular internal ledge formed by the identation 18, or alternatively, the flue terminal may be fitted internally of the ffue, particularly those with supporting ledge therein and additional fastening means such as rivets may be employed if so desired.

Claims

1. A method of fabricating a flue terminal comprising the steps of folding a metal sheet round a former into a cylindrical flue duct shape of generally uniform cross-section, joining along the longitudinal edges parallel to the duct axis and forming an annular indentation in the wall of the flue body to act as a stiffening rib.

2. A flue terminal comprising a single folded metal sheet forming a cylinder closed by an overlapping longitudinal edge join and incorporating a continuous annular indentation as a stiffening section in the flue body at or adjacent one end for insertion in or attachment to the flue, the opposite end of the flue terminal body incorporating a series of part-annular vents in the flue terminal wall and being fitted with an end cap formed by a separate pressing with an overlapping rim into which the main flue terminal body is received.