GB2119921A - Fuel-effect gas fire - Google Patents

Abstract

A fuel-effect gas fire has a burner 1, a vertical first array 4 of radiants 5 and a wall 6 spaced therefrom to define a passage 7 for the product stream from the burner and a second array 10 of radiants 11 leading rearwardly from the top of the first array, the second array forming a bed for loose material 15 adapted to glow without combusting when heated by the product stream. A heat resistant glass cowl 16 can be provided above the array 10 of radiants without reducing heat radiated from the array 4. A down-draught diverter assembly 38 is provided with an upper wall 45 to direct any down-draught away from the flue spigot 37 so that flue products are not prevented from leaving the fire through the flue spigot. <IMAGE>

Description

SPECIFICATION A gas fire Technical field The present invention relates to gas fires and is particularly concerned with a gas fire which is intended to imitate a solid fuel fire, that is a fire which appears to be burning such fuel as wood, coal or coke but is actually gas-fired. Such fires have been previously proposed and are commonly, and hereinafter, referred to as "fuel-effect fires".

Background art Previously proposed fuel-effect fires incorporate a gas burner and immediately adjacent thereto a bed for fuel-effect material which bed is permeable to air and to the product stream of the burner. The fuel-effect material comprises individual pieces having the appearance of, for example, wood or coke and usually made of a ceramic material which is adapted to glow without combusting at the temperature of the product stream.The gas burner may be located immediately below the bed so that when the burner is turned down to a low setting, there is merely a glow from the fuel-effect material, but so that when it is on a high setting flames appear around the glowing individual pieces of fuel-effect material. Particulariy where the fuel-effect material is in the shape of logs of wood, the burner may be located at the ievel of the bed, or slightly below it, in orderto produce flames aroung the material whenever the burner is alight.

Such fuel-effect fires are known to provide heat by both radiation and convection. For efficiency and other reasons it is usual to provide a glass screen or cowl in front of the fuel-effect material but this tends to have the effect of reducing the radiation output.

The radiant output of a typical open-fronted gas fire is 30-35% of input, but introduction of the glass screen referred to above has been found to reduce this typically to 18-20% of input.

Statement ofinvention and advantages It is an object of the present invention to provide a fuel-effect fire which is adapted to receive a glass cowl over the fuel-effect material without having the effect of reducing the overall radiation output as aforedescribed, and there is accordingly provided a gas fire comprising a gas burner, a first substantially vertical array of spaced radiants above the burner and first means spaced rearwardly of said array and defining therewith a substantially vertical passage above the burner for the passage of the product stream from the burner, a second array of spaced radiants extending generally rearwardly from said first array and defining the uppermost extent of said substantially vertical passage, and wherein said passage is extended generally rearwardly beneath said second array of radiants and said second array of radiants forms a bed for loose material which is adapted to glow without combusting when heated by said product stream.

By the present invention the gas burner is spaced a considerably greater distance than has hitherto been proposed from the bed whereby thermal radiation output occurs from the first substantially vertical array of radiants as well as from the bed. In practice the gas fire of the present invention will almost always be provided with cowl means substantially enclosing the combustion chamber above the bed is provided, and this is conveniently spaced generally forwardly of and above the second array of radiants and defines at its rearmost extent an opening for the product stream from the second array of radiants to a heat exchanger from which a flue is adapted to receive the product stream, with at least part of the cowl means being formed of heat resistant glass through which the second array of radiants is capable of being viewed and the lower limit of the cowl means being above the lower extent of the first substantially vertical array of radiants so that heat generated by the burner may radiate directly from said first array to the environment from below the cowl means. With such an arrangement it has been found that heat radiated directly from the first array of radiants combined with heat radiated from the cowl means can give a relatively high radiant output of 30-35% of the input comparable with most open-fronted fires.

The gas fire of the present invention may have an advantageous appearance since the first array of radiants is at least partly visible from the environment or room in which the fire is located and may be in the form of the upright array of bars of a grate of a solid fuel fire. A further advantage may thus be gained when the rearwardly-spaced first passagedefining means is visible through the first array of radiant by making, or coating, said first means in a material which glows when heated by the product stream, such as resin-bonded ceramic fibre. Such glowing first passage-defining means may have the appearance of accumulated hot ash.Where a cowl means is provided, it conveniently extends not only above the second array of radiants but also forward thereof. Afire-guard may extend downwardly from the cowl means in front of the first array of radiants to alleviate the likelihood of accidental contact with the latter. Secondary air for combustion heating may be drawn underneath the cowl means as well as between the radiants of the first array, and usually the gas burner will be spaced slightly from the first passage to provide for entry of secondary air into the first passage.

Preferably, the first and second arrays of radiants are connected or bridged at the uppermost extent of the first passage by shaped end parts which assist in guiding the product stream into the extended passage beneath the second array of radiants. Preferably also, the second array of radiants is inclined rearwardly from the first array.

Since the gas burner is substantially spaced from the fuel-effect bed, flames may not appear through the fuel-effect material from the gas burner. If the appearance of flames is desirable, they may be provided, particulariy where the gas fire includes a cowl means, by a flame assembly conveniently located immediately forwardly of the second array of radiants although an alternative rearward position is possible. The flame assembly may comprise a second gas burner which produces a flame over the fuel-effect material.In a preferred embodiment, a perforated gas supply pipe extends across the width of the fire and gas therefrom may be ignited by the fuel bed when it is hot; conveniently, however, the gas supply pipe has spaced holes along its length for the oufflow of gas and there is provided a trough defining a flash tube extending the length of the gas supply pipe adjacent thereto with the gas supply pipe and trough being relatively rotatable so that the holes in the pipe open into the trough whereby a single spark formed by an ignition device at one end of the supply pipe is capable of igniting a flame at every hole in the pipe.

The product stream passing from the fuel bed is generally directed into a heat exchanger over which air passes to provide convection heating. The heat exchanger preferably has two boxes in series with the product stream passing from the fuel bed into the forwardmost one and then into the second rearwardly located box; from there the product stream may pass into the flue. The flue may include a down-draught diverter of a design which minimises any problems caused by down-draught when the fire produces only a small thermal lift. Such a diverter may comprise a nozzle arrangement between two chambers, a first of which chambers receives the flue gases from a flue spigot of the heat exchanger and a second, rearwardly located, chamber defines an easy path for the down-draught, leading the down-draught away from the flue spigot.

Figures in the drawings One embodiment of a gas fire in accordance with the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure lisa sectional side view of the gas fire including a glass cowl and fire guard; Figure 2 is a front view, partly in section, of the gas fire of Figure 1 with the glass cowl and fire guard omitted, and Figures 3 and 4 show respectively the side and front views of an alternative down-draught diverter.

Detailed description of the drawings The gas fire illustrated in Figures 1 and 2 is a fuel-effect fire, that is it has the appearance of being solid-fuel fired, in this case by coal or coke, but is actually wholly gas fired.

A gas burner shown generally shown at 1 is provided at the base of the fire and extends substantially across the width of the fire. The burner 1 has a gas supply pipe 2 extending across the fire which is pierced at spaced locations and from which gas may be ignited manually or automatically in known manner. Avalve arrangement 3 is provided to control the supply of gas to the pipe 2.

Located substantially immediately above the burner is a vertical array 4 of spaced horizontal radiant bars 5 which is clearly visible forwardly of the fire (to the right in Figure 1 ) for example by an occupant of a room in which the fire is located and which may be made of, for example, a suitable ceramic material.

Spaced rearwardly of the vertical array 4 is a thermal insulating back brick 6 which defines with the vertical array 4 a vertical passage 7 directly above the burner 1 forthe product stream of the burner. A support piece 8 between the burner 1 and the vertical array 4 and back brick 6 provides openings 9 immediately above the burner for the entry of secondary air to the passage 7. Secondary air may also enter the passage 7 between the lowermost of spaced horizontal radiant bars 5. The back brick 6 will be heated by the gas burner 1 and by the product stream therefrom, and is advantageously formed of bonded ceramic fibre which glows when heated but is not otherwise substantially affected by the heat developed by the burner 1. Such glowing is advantageous for reasons which will be described hereinafter.

The uppermost extent of the vertical array 4 of radiants 5 is defined by an upper horizontal radiant part 5a which mates with a second array 10 of spaced horizontal radiants 11 which is inclined upwardly and rearwardly therefrom and which may also be formed of a suitable ceramic material. The lower radiant 1 1a of the array 10 defines with the radiant part 5a the uppermost extent of the vertical passage 7, the two radiant parts 5a and 1 1a together having a solid surface which defines a corner that deflects the product stream from the gas burner 1 out of the vertical passage 7 into an extension 12 thereof beneath the second array 10 of radiants.A second thermal insulating back brick 13 extending rearwardly in inclined manner from the back brick 6 defines an opposed surface of said extended passage 12, said inclination of the back brick 13, as shown, being the same as the inclination of the second array 10 of radiants. The second back brick 13 may comprise a material which glows when heated by the product stream. The extended passage 12 is restricted at it rearmost end by a third thermal insulating back brick 14, which may also glow when heated, whereby the product stream from the gas burner 1 is directed upwardly from the extended passage 12 between adjacent radiants 11 of the second array 10 and between the array 10 and the back brick 13. The second array 10 of radiants act as a bed for particulate material 15 which simulates solid fuel.Each lump of particulate material 15 may be formed of a bonded ceramic fibre which glows when it is heated by the product stream from the gas burner passing therearound but is otherwise sub stantially unaffected by the heat of the product stream.

Heat generated by the gas burner 1 accordingly passes up the vertical passage 7 as well as radiating out from between the radiant bars 5 of array 4. At the same time, the heat in the product stream may cause back brick 6 to glow. The product stream passes from the vertical passage 7 into the extended passage 12 and up through the bed of particulate material 15 which is heated thereby and caused to glow in simulation of solid fuel. The first array 4 of radiant bars has the appearance of the front of a fire grate and the glowing back brick 6 may simulate ash in a fire grate to give the gas fire a greater appearance of a solid-fuel fire.

In the embodiment shown (not shown in Figure 2), a substantially glass cowl 16 is provided above and forwardly of the second array 10 of radiants to collect the rising product stream. The glass of the cowl 16 is transparent whereby the particulate material 15 is visible therethrough and extends downwardly in dog-leg manner to the level of the mating radiant parts 5a and 1 lea, but forwardly thereof whereby secondary air may enter the space beneath the cowl 16 between the radiant part 5a and lowermost part 17 of the cowl 16. Afireguard 18 (not shown in Figure 2) depends from the part 17 to provide protection from the hot radiants 5 and comprises spaced bars 19 between which the first array 4 and the firebrick 6 are visible.

The heat radiated from the first array 4 combined with that radiated from the cowl 16 may comprise 30-35% of the thermal energy input. The upper portion 20 of the dog-leg of cowl 16 is inclined upwardly and rearwardly to direct the product stream therebeneath towards an orifice 21 leading upwardly behind the portion 20 into a heat exchanger assembly 22. A canopy (not shown) will generally be provided upwardly behind the portion 20 into a heat exchanger assembly 22. A eanopy (not shown) will generally be provided over the heat exchanger assembly 22 and part of the cowl 16 to direct air thereover for convection heating and such an arrangement can lead to 70% efficiency in the use of the thermal energy input.

Because the bed of particulate material 15 is substantially spaced from the gas burner 1, flames from the gas burner may not be visible around the particulate material. it may be desirable in fuel-effect fires to provide the appearance of a flame in the particulate material and an artificial flame assembly 23 is located forwardly of the second arry 10 of radiant bars 11 to give such an appearance. The assembly 23 comprises a gas supply pipe 24 extending across the width of the fire immediately forwardly of the mating radiant parts 5a and 1 1a and having spaced openings 25 therealong which are directed upwardly and rearwardly for the outflow of gas. A gas supply valve 26 is provided at one end of the pipe 24 and receives mains gas at 27.The valve 26 is manually operable to control the supply of gas to the pipe 24 and when open, gas emitted from the openings 25 may be automatically ignited by the particulate material 15 when the latter is fully heated by the product stream. The flames 28 at openings 25 play over the particulate material 15 and at least when viewed through the glass of cowl 16 may have the appearance of being omitted from around the particulate material 15.

In order to light the artificial flame assembly 23 as soon as the gas fire is lit, there is advantageously provided an automatic ignition assembly 29 which is shown includes a piezo-electric spark assembly 30 and an electrode device 31. Also provided is an elongate trough 32 which extends immediately forwardly of and the length of the gas supply pipe 24. The trough 32 opens into the gas supply pipe 24 and the latter is rotatable, preferably against biasing means (not shown) so that the openings 25 are temporarily directed into the trough 32 during ignition. Such rotation of the gas supply pipe 24 occurs automatically on moving the gas supply valve 26 into an ignition position in which gas is directed into the pipe 24 and through the openings 25 into the trough 32.In the ignition position of the valve 26, the spark assembly 30 and electrode device 31 ignite the gas at the end of the trough 32 thereadjacent, such flame igniting the gas along the full length of the trough. After ignition the valve 26 is moved into an "on" position and the pipe 24 is returned to its operative position by the biasing means. In such operative position the openings 25 are directed away from the trough 32 and individual flames 28 occur at the openings.

The heat exchanger 22 which receives the product stream from the particulate material 15 by way of the orifice 21 is a two-box arrangement to provide optimum heat transfer. Orifice 21 opens into the bottom of a front box 33 and heat is exchanged from the product sream particularly over the transfer surface 34. The front box 33 and a rear box 35 are connected by an opening 36 and the cooling product stream passes therethrough from the front box downwardly to a flue spigot 37 which opens into a down-draught diverter assembly 38 which is located in the entrance to the flue 39.

In view of the potential high thermal efficiency of the gas fire of the present invention it may produce only a small thermal lift in the flue which could make the fire more sesceptible to down-draught. The down-draught diverter assembly 38 illustrated in Figure lisa novel design which aims to direct any down-draught away from the flue spigot 37 so that the flue products are not prevented from leaving the fire by way of the flue spigot. The assembly 38 comprises an inner chamber 40 and an outer chamber 41. The inner chamber 40 is closed to the room in which the fire is located and receives the flue spigot 37 centrally in its front wall 42 which forms part of the flue closure plate 51.A sheet metal structure defines the back and bottom walls 43 and 44 with the back wall 43 extending substantially parallel to the front wall 42 and the bottom wall 44 extending therefrom to substantially close with the front wall 42. An upper wall 45 of the inner chamber 40 is defined by an inclined metal structure which at its rearward, lower end overhanges the back wall 43 and defines therewith a nozzle 46 by which the flue products enter the outer chamber 41 from the inner chamber 40. The inner and outer chambers have common side walls 47 (one shown in Figure 1) and the outer chamber 41 extends around the back of the inner chamber but is open at its upper end 40 and at its lower end 49. The lower end 49 of the outer chamber opens into the room in which the fire is located, behind the fire, through an opening 50 provided in the closure plate 51. The upper end 48 of the outer chamber 41 opens into the flue 39 and a plate 52 overlies the open upper end 48 to alleviate the likelihood of material entering the outer chamber therethrough.

Generally, the thermal lift of the fire is sufficient to carry the flue products from the inner chamber 40 through the nozzle 46 into the outer chamber 41 and through the open upper end 48 into the flue 39. On the few occasions when there is a down-draught, this will enter the outer chamber 41 from the flue through the open upper end 48 but be deflected from the nozzle 46 and the inner chamber 40 by the inclined upper wall 45 of the inner chamber. The down-draught may then exit from the outer chamber 41 into the room by way of opening 50 without restricting the exit of the flue products from the flue spigot 37.The shape of the nozzle 46 may have the advantageous effect that when the down-draught is diverted by the upper wall 45 of the inner chamber it creates a negative pressure in the outer chamber 41 adjacent the nozzle 46 which assists in drawing the flue products out of the inner chamber.

An alternative down-draught diverter assembly 53 is shown in Figures 3 and 4 welded to a flue closure plate 54 which replaces the flue closure plate 51 of Figures 1 and 2. The plate 54 has a rectangular opening 55 therein of equivalent width to the assembly 53, the opening 55 being extended upwardly at 56 centrally of the upper edge 57 to receive the flue spigot 37 with the extension portion 56 being narrower than the opening 55. The assembly 53 overlies the opening 55 and extension portion 56 on the side of the plate 54 remote from the fire and has oppositely inclined upper and lower walls 58 and 59 and side walls 60 welded to the plate 54. A back wall 61 extends parallel to the plate 54. A back wall 61 extends parallel to the plate 54 between the upper wall 58, the lower wall 59 and the side walls 60 to define a box capable of receiving the flue products from the flue spigot 37.Entry of the flue products to the flue 39 is by way of two spaced slots 62 at the respective lateral extremities of the inclined upper wall 58 of the diverter assembly 53. Cover plates 63 are welded overthe slots 62 to alleviate the iikelihood of debris in the flue falling through the slots while permitting the passage of the flue products around the cover plates 63. In the event of a down-draught in the flue, this is abie to pass downwardly through slots 62 and through the opening 55 in the flue closure plate 54 into the room in which the fire is provided while the flue products exit from the flue spigot 37 centrally between the slots 62.The slots 62 overlie the plate 54 rather than the opening 55 or extension portion 56 therein so that in normal use when there is no down-draught the flue products are restrained from directly entering the room by the plate 54.

CLAIMS (Filed on 4 Mar 1983) 1. A fuel-effect gas fire comprising a gas burner, a substantially vertical first array of spaced radiants above the burner and first means spaced rearwardly of said first array and defining therewith a substantially vertical passage above the burner for the passage of the product stream from the burner, a second array of spaced radiants extending generally rearwardly from said first array and defining the uppermost extent of said substantially vertical passage, said passage being extended generally rearwardly beneath said second array of radiants which forms a bed for loose material which is adapted to glow without combusting when heated by said product stream.

2. A fuel-effect gas fire as claimed in Claim 1, comprising a cowl spaced generally forwardly of and above the second array of radiants.

3. A fuel-effect gas fire as claimed in Claim 2, in which the cowl defines, at its rearmost extent an opening for the product stream from the second array of radiants to a heat exchanger from which a flue is adapted to receive the product stream.

4. A fuel-effect gas fire as claimed in Claim 3, in which at least part of the cowl is formed of heat resistant transparent glass through which the second array of radiants is capable of being viewed.

5. A fuel-effect gas fire as claimed in Claim 4, in which the lower limit of the cowl is above the lower extent of the first array of radiants so that heat generated by the burner may radiate directly from the first array to the environment from below the coal.

6. A fuel-effect gas fire as claimed in any one of the preceding claims, in which said first means is made of or coated with a material which glows when heated by the product stream, said glowing being visible from in front of the fire through the first array of radiants to give the appearance of hot ash.

7. A fuel-effect gas fire as claimed in Claim 6, in which said material is resin-bonded ceramic fibre.

8. A fuel-effect gas fire as claimed in any one of Claims 2 to 7, in which a fire guard extends downwardly from the cowl in front of the first array of radiants.

9. A fuel-effect gas fire as claimed in any one of the preceding claims, in which the first and second arrays of radiants are connected or bridged at the uppermost extent of the first passage by shaped end parts which assist in guiding the product stream into the extended passage beneath the second array of radiants.

10. A fuel-effect gas fire as claimed in any one of the preceding claims, in which a flame assembly is provided adjacent to the second array of radiants to simulate the flames of a solid fuel fire.

11. A fuel-effect gas fire as claimed in Claim 10, in which the flame assembly includes a second gas burner in the form of a predetermined gas supply pipe extending across the width of the fire.

12. A fuel-effect gas fire as claimed in Claim 11, in which extending the length of the gas supply pipe there is a flash tube in the form of a trough, the pipe and trough being relatively rotatable so that the perforations in the pipe open into the trough whereby a single spark formed by an ignition device at one end of the pipe is capable of igniting gas emerging at every perforation in the pipe.

13. A fuel-effect gas fire as claimed in Claim 3, in which the heat exchanger has two boxes in series.

14; Afuel-effect gas fire as claimed in Claim 13, in which the flue includes a down-draught diverter which diverts any down-draught from the flue when the fire produces small thermal lift.

15. A fuel-effect gas fire as claimed in Claim 14, in which the diverter comprises a nozzle arrangement between the two chambers, a first of which chambers receives the flue gases from a flue spigot of the heat exchanger and a second, rearwardly located, chamber defines an easy path for the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (16)

**WARNING** start of CLMS field may overlap end of DESC **. this will enter the outer chamber 41 from the flue through the open upper end 48 but be deflected from the nozzle 46 and the inner chamber 40 by the inclined upper wall 45 of the inner chamber. The down-draught may then exit from the outer chamber 41 into the room by way of opening 50 without restricting the exit of the flue products from the flue spigot 37. The shape of the nozzle 46 may have the advantageous effect that when the down-draught is diverted by the upper wall 45 of the inner chamber it creates a negative pressure in the outer chamber 41 adjacent the nozzle 46 which assists in drawing the flue products out of the inner chamber. An alternative down-draught diverter assembly 53 is shown in Figures 3 and 4 welded to a flue closure plate 54 which replaces the flue closure plate 51 of Figures 1 and 2. The plate 54 has a rectangular opening 55 therein of equivalent width to the assembly 53, the opening 55 being extended upwardly at 56 centrally of the upper edge 57 to receive the flue spigot 37 with the extension portion 56 being narrower than the opening 55. The assembly 53 overlies the opening 55 and extension portion 56 on the side of the plate 54 remote from the fire and has oppositely inclined upper and lower walls 58 and 59 and side walls 60 welded to the plate 54. A back wall 61 extends parallel to the plate 54. A back wall 61 extends parallel to the plate 54 between the upper wall 58, the lower wall 59 and the side walls 60 to define a box capable of receiving the flue products from the flue spigot 37.Entry of the flue products to the flue 39 is by way of two spaced slots 62 at the respective lateral extremities of the inclined upper wall 58 of the diverter assembly 53. Cover plates 63 are welded overthe slots 62 to alleviate the iikelihood of debris in the flue falling through the slots while permitting the passage of the flue products around the cover plates 63. In the event of a down-draught in the flue, this is abie to pass downwardly through slots 62 and through the opening 55 in the flue closure plate 54 into the room in which the fire is provided while the flue products exit from the flue spigot 37 centrally between the slots 62.The slots 62 overlie the plate 54 rather than the opening 55 or extension portion 56 therein so that in normal use when there is no down-draught the flue products are restrained from directly entering the room by the plate 54. CLAIMS (Filed on 4 Mar 1983)

1. A fuel-effect gas fire comprising a gas burner, a substantially vertical first array of spaced radiants above the burner and first means spaced rearwardly of said first array and defining therewith a substantially vertical passage above the burner for the passage of the product stream from the burner, a second array of spaced radiants extending generally rearwardly from said first array and defining the uppermost extent of said substantially vertical passage, said passage being extended generally rearwardly beneath said second array of radiants which forms a bed for loose material which is adapted to glow without combusting when heated by said product stream.

2. A fuel-effect gas fire as claimed in Claim 1, comprising a cowl spaced generally forwardly of and above the second array of radiants.

3. A fuel-effect gas fire as claimed in Claim 2, in which the cowl defines, at its rearmost extent an opening for the product stream from the second array of radiants to a heat exchanger from which a flue is adapted to receive the product stream.

4. A fuel-effect gas fire as claimed in Claim 3, in which at least part of the cowl is formed of heat resistant transparent glass through which the second array of radiants is capable of being viewed.

5. A fuel-effect gas fire as claimed in Claim 4, in which the lower limit of the cowl is above the lower extent of the first array of radiants so that heat generated by the burner may radiate directly from the first array to the environment from below the coal.

6. A fuel-effect gas fire as claimed in any one of the preceding claims, in which said first means is made of or coated with a material which glows when heated by the product stream, said glowing being visible from in front of the fire through the first array of radiants to give the appearance of hot ash.

7. A fuel-effect gas fire as claimed in Claim 6, in which said material is resin-bonded ceramic fibre.

8. A fuel-effect gas fire as claimed in any one of Claims 2 to 7, in which a fire guard extends downwardly from the cowl in front of the first array of radiants.

9. A fuel-effect gas fire as claimed in any one of the preceding claims, in which the first and second arrays of radiants are connected or bridged at the uppermost extent of the first passage by shaped end parts which assist in guiding the product stream into the extended passage beneath the second array of radiants.

10. A fuel-effect gas fire as claimed in any one of the preceding claims, in which a flame assembly is provided adjacent to the second array of radiants to simulate the flames of a solid fuel fire.

11. A fuel-effect gas fire as claimed in Claim 10, in which the flame assembly includes a second gas burner in the form of a predetermined gas supply pipe extending across the width of the fire.

12. A fuel-effect gas fire as claimed in Claim 11, in which extending the length of the gas supply pipe there is a flash tube in the form of a trough, the pipe and trough being relatively rotatable so that the perforations in the pipe open into the trough whereby a single spark formed by an ignition device at one end of the pipe is capable of igniting gas emerging at every perforation in the pipe.

13. A fuel-effect gas fire as claimed in Claim 3, in which the heat exchanger has two boxes in series.

14; Afuel-effect gas fire as claimed in Claim 13, in which the flue includes a down-draught diverter which diverts any down-draught from the flue when the fire produces small thermal lift.

15. A fuel-effect gas fire as claimed in Claim 14, in which the diverter comprises a nozzle arrangement between the two chambers, a first of which chambers receives the flue gases from a flue spigot of the heat exchanger and a second, rearwardly located, chamber defines an easy path for the

down-draught, leading the down-draught away from the flue spigot.

16. A fuel-effect gas fire substantially as herein described with reference to Figure 1 and Figure 2 or Figure 3 of the accompanying drawings.