GB2139338A - Flue system - Google Patents

Abstract

A flue system for use in timber- framed buildings is built up from precast concrete flue blocks 1 which have no external locating nibs. The flue blocks are located one above another by a metal sleeve 3 which slides into the flue passage 2 and bridges the joint between adjacent blocks. Lugs 4 pressed out of the sleeve 3 lie in the joint and hold the sleeve in position. The sleeve 3, and the flue system, are secured to a timber framework by clips 5 which engage the sleeve and which lie in and extend beyond the joint between adjacent blocks. The sleeves 3 also prevent mortar laid between adjacent blocks from extruding into the flue passage. <IMAGE>

Description

SPECIFICATION Flue system In new dwellings having brick or block walls flues for domestic gas fires or boilers are conventionally provided by use of pre-cast concrete flue blocks containing an internal flue passage. The blocks are provided with alternate handed horizontal nibs which interlock with the adjacent brick or block courses.

The flue blocks are accordingly produced to the same dimensions as the bricks or blocks.

The blocks also interlock with each other vertically through an upstanding lip surrounding the flue passage on the upper surface and a corresponding rebate in the lower surface.

These blocks are clearly unsuitable for use in constructions not using bricks or blocks.

With the current increasing interest in timberframed dwellings there is a need for a flue system having the easy building properties of conventional pre-cast units but which can be erected without interlocking with the building structure.

The present invention provides a flue system in which flue blocks are located one above another using a sleeve whose external dimensions match the internal dimensions of the flue passage in the flue block, so that the sleeve is a sliding fit in the flue passage. The sleeve is positioned so as to bridge the joint between adjacent blocks and has outwardly projecting lugs to support it on the uppermost surface of a flue block during assembly, so that the lugs lie in the joint between adjacent blocks.

The flue system may be stabilised against the building structure by use of metal clips having one end portion which engages the sleeve, an intermediate portion which lies in the joint between blocks and extends beyond the joint and in which the other end portion is secured to the building structure, e.g. the timber frame.

Because the flue blocks are secured to a support through the sleeve, the blocks may be manufactured without external locating nibs.

Also the locating action of the sleeve means that upstanding lips and rebates for vertical interlocking of the flue blocks may be omitted.

As there is no longer any need for an interlock with brick or block courses, the flue blocks can be produced in greater lengths.

thus further simplifying construction.

The joint between adjacent flue blocks is sealed with mortar as with conventional system, and the sleeve gives the added advantage of preventing mortar from being extruded into the flue passage and causing a restriction of the draught through the flue passage.

An embodiment of this invention will now be described in more detail making reference to the accompanying drawings, in which: Figure 1 is an isometric view of a sleeve positioned ready for location in a flue block and also shows fixing clips attached to the sleeve, Figure 2 is a sectional view through a joint made- between two flue blocks using a sleeve as shown in Fig. 1, Figure 3 shows the connection of a flue block to other flue elements.

Figure 4 is an isometric view showing a starter flue block positioned against a wall.

Referring to Fig. 1 of the drawings, a preferred form of the flue system of this invention uses precast concrete flue blocks 1 which are in general symmetrical in crosssection across the flue passage and of constant wall thickness. No external nibs for connection to brick or block courses are needed and also no upstands or rebates for connecting adjacent blocks. Clearly the flue block is thus greatly simplified compared to blocks used in more conventional building structures. Because there is no need to relate the flue blocks to the courses of the building structure, the blocks can be produced in much greater lengths (e.g. 1 200 mm) than hitherto and than shown in the purely illustrative Fig.

1. A more accurate representation of the relative dimension 5 which can be adopted in actual use are shown in Fig. 3.

A metal sleeve 3, which may be folded from sheet metal, preferably stainless steel, is dimensioned to slide into the flue passage 2 of the flue block 1. Lugs 4 are pressed out of the sleeve substantially centrally of each face of the sleeve. When the sleeve is positioned in the flue passage the lugs bear against the horizontal surface of the flue block and locate the sleeve with half its depth within the flue passage. The other half of the sleeve projects from the flue passage to be available for location in the flue passage of the next block of the flue system.

Before the next block is added to the flue, retaining clips 5 are mounted on the sleeve (or may be already attached) and a bed of mortar is laid on the horizontal surface of the block. This surface may be provided with a channel 6 to provide a key for the mortar. The sleeve prevents mortar entering the flue passage both during laying of the mortar and when the next block is pressed home. Thus the sleeve ensures a smoother flueway than hitherto and thus smoother gas flow through the flue.

The clips 5 are also preferably folded from stainless steel sheet. The end 5A is folded so as to slot over the sleeve leaving the midportion 5B lying against the horizontal block surface when the sleeve is in position. The portion 5B extends beyond the block and terminates in the upright end portion 5C which is apertured for bolting or screwing to a timber frame or other part of a building structure. Once the clips have been secured to the structure the next block can be added.

A section through a joint formed in this way between flue blocks 11 and 1 2 is shown in Fig. 2. This sectional view shows clearly how the sleeve 1 3 prevents mortar 1 4 from entering the flue passage and at the same time positively located the upper flue block 11 on the lower block 1 2. Retaining clips 1 5 at tached to the sleeve 1 3 are attached to a timber frame 1 6 by screws 1 7 to stabilise the system.

As with conventional systems, to build up a flue system appropriate for a particular building, flue blocks of various shapes can be used to provide bends, junctions, terminals and connectors e.g. for a flue pipe, as shown in Fig. 3.

Fig. 4 shows a flue block 21 secured to a timber framed structure through clips 25 engaged with a sleeve 23. In this case the flue block is a starting block which has an aperture 36 to form an entry point for a gas appliance.

This starting block may be provided with a base 27 closing the flue passage for added strength and to assist in fixing the unit to the floor.

By producing flue blocks in an insulating grade of concrete, and providing the fixings behind the stack, and with the reduced number of joint lines, it may be possible to plaster the outer surface of the flue directly, or even decorate directly, with obvious economies. Alternatively, a simple batten and board covering may be provided as shown in Fig. 4. The horizontal portion 5B of the clips 5 may be extended if desired to space the flue from the building structure for addition of rear insulation.

Claims (6)

1. A fiue system comprising flue blocks located one above another by sleeves dimensioned to be a sliding fit within the flue passage of the blocks, each sleeve being positioned to bridge the joint between adjacent blocks and being supported at that position by outwardly projecting lugs which lie in the joint between adjacent blocks.

2. A flue system as claimed in claim 1 in which the surfaces of the flue blocks which form a joint with an adjacent flue block are provided with a channel or other recesses to provide a key for a mortar bedding layer between adjacent blocks.

3. A flue system as claimed in claim 1 or 2 including clips each having one end portion engaging a sleeve, an intermediate portion lying in a joint between adjacent blocks and the other end portion secured to a support structure.

4. A flue system as claimed in claim 1, 2 or 3 in which the sleeve is a metal band and the lugs are formed by piercing and folding portions of the band.

5. A flue system comprising precast concrete flue blocks having no external locating nibs or rebates, the flue blocks being located one above another using a metal sleeve whose external dimensions match the internal dimensions of the flue passage in the flue block, the sleeve being positioned so as to bridge the joint between adjacent blocks and having outwardly projecting lugs to support it on the uppermost surface of a flue block during assembly of the system.

6. A flue system substantially as described herein with reference to the accompanying drawings.