GB2356452A

GB2356452A - Domestic gas fire

Info

Publication number: GB2356452A
Application number: GB9920260A
Authority: GB
Inventors: James Corbett; Prakash Patel
Original assignee: MAGIGLO Ltd
Current assignee: MAGIGLO Ltd
Priority date: 1999-08-26
Filing date: 1999-08-26
Publication date: 2001-05-23
Anticipated expiration: 2019-08-26
Also published as: GB9920260D0; GB2356452B

Abstract

A domestic gas fire includes a refractory fireback (20) located behind and above a combustion region of the fire. The fireback includes a plurality of openings (21) through which hot flue gases produced in the combustion region pass to an exhaust flue outlet (26) at the rear of the fireback. The openings are preferably formed as louvre openings. After passing through the openings, the hot flue gases may flow around a heat exchange (22) disposed behind the fireback, the heat exchanger having an internal passage for the flow of convected air. The heat exchanger may include an array of parallel tubular ducts. Artificial coals or logs (33) may be stacked on a ceramic fibre matrix block (18). The matrix block (18) and the fireback (20) may be a moulded one-piece structure.

Description

2356452 DOMESTIC GAS FIRES This invention relates to a domestic gas fire

in which diffused gas is ignited beneath a bed of artificial coals or logs and flows upwardly to create the effect of a real coal or log fire.

Traditionally, such fires, while providing a realistic in-ftation of a coal or log fire, have allowed much of the heat generated by combustion to escape with the flue gases. This problem has been alleviated to some extent by providing fires in which a room is heated by a combination of radiation and convection. In a convector gas fire, cool air drawn in beneath the fire bed is able to pass up and around the back of a firebox containing the bumer unit so that the air is heated before emerging into the room at the top of the firebox. However a significant amount of heat is still lost with the hot flue gases which exit through a slot at the rear of the firebox into an exhaust flue or chimney. Restricting the slot reduces the heat loss but increases the risk of flue gases spilling out into the room, so that a canopy is normally installed at the top of the firebox to deflect the flue gases toward the exhaust slot at the rear of the firebox. Such a canopy generally detracts from the appearance of the fire.

Attempts to increase the radiant heat output by forming the fireback of refractory materials that reflect a greater proportion of the incident heat have been partially successful, but the increase in radiant heat is offset by a reduction in the convected heat. This arises because less heat is transmitted through the fireback to heat the convected air.

According to a first aspect of the present invention there is provided a domestic gas fire wherein a refractory fireback is located behind and above a combustion region of the fire, and wherein the fireback includes an opening communicating with an exhaust outlet, the opening being located such that hot flue gases produced in the combustion region pass through the opening to the exhaust outlet.

1) Preferably the opening is formed in a forwardly inclined wall of the fireback disposed above the combustion region, and preferably the wall includes a plurality of such openings. In this case the openings are preferably horizontal openings disposed one above the other, and each opening is preferably formed behind a forwardly projecting portion of the inclined wall. The respective forwardly projecting portions of the wall preferably overlap one another such that the openings appear as louvre openings.

In this manner a domestic gas fire is produced which has a fireback capable of radiating a substantial amount of heat into the room but which no longer requires an overhead canopy to prevent spillage of the flue gases into the room. In effect the louvre openings form a series of minicanopies.

In a preferred embodiment of the invention the fire is a convector fire and the opening or openings in the fireback are located adjacent a heat exchanger such that the hot flue gases flow around the heat exchanger after passing through the opening or openings and before emerging from the outlet- In the heat exchanger the hot flue gases heat a flow of convected air passing around the back of the fire, the heated air then passing into the room being heated to supplement the heat provided by radiation.

Preferably the heat exchanger comprises a plurality of tubular channels through which the convected air flows, and the hot flue gases circulate around the channels before passing through the exhaust outlet. Preferably at least one of the openings 'in the fireback is located at a level below the outlet such that the hot flue gases flow upwardly in a direction parallel to the channels while -traversing the channels to the outlet.

In this manner a substantial length of each tubular channel is in direct contact with the hot flue gases and an efficient heat exchanger uni't is formed.

According to a second aspect of the invention there is provided a domestic gas fire wherein a refractory fireback is provided behind and above a combustion region of the 3 fire, and wherein artificial coals or logs are supported on a block of refractory material in the combustion region, the fireback and the block of refractory material being moulded as an integral one-piece structure. The reftactory material is preferably a ceramic fibre material.

By way of example only, a domestic gas fire embodying the invention will now be described with reference to the accompanying drawings in which:

Fig. I is diagrammatic sectional view through a domestic gas fire-, Fig. 2 is a schematic front view of the fire; Fig. 3 illustrates a heat exchanger used in the fire, Fig. 4 is a section on fine A-A in Fig. 5, and Fig. 5 is a front view of a combined matrix block and fireback moulded as one unit.

Referring to these figures, the fire consists of a firebox 10 formed of sheet metal and having opposed side walls 11, 12, a top wall 13 a bottom wall 14, and a hollow rear wall consisting of an outer skin 15 and an inner skin 16.

The firebox also includes a shelf 17 supporting a ceramic fibre matrix block 18 upon which the artificial coals or logs 33 are stacked. Beneath the shelf 17 area burner unit 19 with a gas diffuser 34, and the various controls (not shown) for controlling the fire.

Integrally moulded with the matrix block 18 is a ceramic fibre fireback 20 which includes louvre openings 21 through which the hot flue gases pass when the fire is ignited. After passing through the openings 2 1, the hot flue gases flow up and around a series of parallel tubular ducts 23 forming a heat exchanger 22 located in the hollow rear wall of the firebox between the inner and outer skins 15, 16, 4 The ceramic matrix block 18 insulates the metal shelf 17 and increases the radiant heat output of the fire. It also includes channels 41 shaped to control secondary aeration and therefore provides greater control of the combustion process. By moulding the matrix block 18 and the fireback 20 as an integral one-piece structure, the manufacture of the fire is simplified.

The sides of the fireback 20 taper rearwardly and inwardly, and the louvre openings 21 extend the full width of a forwardly miclined rear wall 38 disposed over the combustion region of the fire. The fireback 20 not only increases the radiant heat output of the fire but improves the combustion process by increasing the temperature of the gases in the combustion region.

The provision of the louvre openings 21 in the fireback 20 reduces the tendency of the flue gases to spill out into the room and the fire can therefore be constructed without the need for a canopy to retain the flue gases. This enhances the appearance of the fire.

The louvre openings 2 1 are formed by overlapping ribs 3 7 in the forwardly sloping wall 3 8 of the fireback, the openings being formed behind the respective ribs such that the openings are obscured when viewing the fireback from the front as in Fig. 5 - As can be seen from Fig. 3 the parallel tubular ducts 235 of the heat exchanger 22 are spaced apart from one another and interconnected by upper bounding flanges 24 and lower flanges 25 which are rivetted respectively to the outer skin 15 and the inner skin 16 of the hollow rear wall. The area bounded by the flanges 24 and 25 and containing the ducts 23 is aligned with cut-outs in the inner and outer skins so that the hot flue gases emerging from the openings 21 in the fireback are able to flow around and between the ducts 23 before emerging from the firebox through an outlet 26 communicating with a flue at the top of the hollow rear wall. Since the openings 21 are located at a level below that of the outlet 26, the flue gases will flow upwardly in a direction parallel to the ducts while at the same time traversing the ducts to reach the outlet 26. The lower edge of the outlet 26 is formed by the top edge of a cover 27 partially covering the cut-out in the outer skin 15 of the hollow rear wall, the top edge of the cover including a ridge 40 such that the cover is spaced a small distance clear of the outer skin to allow the flue gases to circulate around the ducts 23.

The ducts 2') contain cool air drawn in by convection at the bottom of the firebox as shown by the arrows 28 in Fig. 1, the cool air passing upwardly between the inner and outer skins of the hollow rear wall and through the tubular ducts 23 where the air is heated before passing out into the room through a slot 29 'in the front of the firebox.

It can be seen therefore that the hot flue gases will be in direct contact with the heat exchanging ducts 2') over a substantial length of the ducts before finally emerging from the firebox through the outlet 26. Compared to known convector fires, a greater proportion of heat is therefore transferred from the flue gases to the convector air for heating the room space, and a more efficient fire is achieved.

A decorative trim 3 5 (shown in dashed outline in Fig. 2) is fitted over a pair of side flanges 30, 31 and a top flange 32 at the front of the firebox, the transverse top of the trim including a slot 36 aligned with the slot 29, and acting to retain the fireback/matrix 18, 20 within the firebox.

UK 9920260.8

Claims

CLAIMS:

1. A domestic gas fire wherein a refractory fireback is located behind and above a combustion region of the fire, the fireback including an opening located such that hot flue gases produced in the combustion region pass through the opening to an exhaust flue outlet at the rear of the fireback.

2. A domestic gas fire according to claim I wherein the opening is formed in a forwardly inclined wall of the fireback disposed above the combustion region.

3. A domestic gas fire according to claim 2 wherein the wall includes a plurality of the said openings.

4. A domestic gas fire according to claim 3 wherein the openings comprise generally horizontal openings disposed one above the other, each opening being formed behind a respective forwardly projecting portion of the inclined wall.

5. A domestic gas fire according to claim 4 wherein the respective forwardly projecting portions of the wall overlap one another to form louvre openings.

6. A domestic gas fire according to any one of the preceding claims wherein the fire is a convector fire having a heat exchanger disposed behind the fireback, the heat exchanger having an internal passage for the flow of convected air, and the opening or openings in the fireback being located adjacent the heat exchanger such that the hot flue gases flow around the heat exchanger after passing through the opening or openings and before passing through the exhaust outlet.

7. A domestic gas fire according to claim 6 wherein the internal passage in the heat exchanger comprises a plurality of parallel tubular channels spaced apart from one another, the hot flue gases traversing the channels before passing through the exhaust outlet.

UK 9920260.

8 1 8. A domestic gas fire according to claim 7 wherein at least one of the openings in the fireback is located at a level below the exhaust outlet such that the hot flue gases flow upwardly to the outlet in a direction parallel to the tubular channels.

9. A domestic gas fire according to any one of the preceding claims wherein the refractory fireback comprises a ceramic fibre material.

10, A domestic gas fire wherein a refractory fireback is provided behind and above a combustion region of the fire, and wherein artificial coals or logs are supported on a block of refractory material in the combustion region, the fireback and the block of refractory material being moulded as an integral one-piece structure.

11. A domestic gas fire according to claim 10 wherein the refractory material is a ceramic fibre material.