GB2547000A

GB2547000A - Heating apparatus and valve assembly

Info

Publication number: GB2547000A
Application number: GB1601971.3A
Authority: GB
Inventors: Anthony Byrne William
Original assignee: Basic Holdings
Current assignee: Basic Holdings
Priority date: 2016-02-03
Filing date: 2016-02-03
Publication date: 2017-08-09
Also published as: GB201601971D0

Abstract

A heating apparatus has a burner assembly 14 having first 28 and second 30 burners and a controller such as a valve 60 to supply fuel separately to the first and second burners. Combustion of fuel at the first burner 28 is sufficient to ignite fuel supplied to the second burner 30. This may be achieved by means of a row of apertures 50,52 at which flames are produced on combustion of fuel. Fuel may be supplied to the second burner only if fuel is also supplied to the first burner. The burners may comprise a burner body with a plurality of apertures 40,44 that produce flames on combustion. The first burner may have secondary apertures to produce flames adjacent to the second burner that may also form a path to the second burner. The burners may have elongate primary regions 40,44 for combustion that may overlap. Another embodiment is for a valve assembly with three valves each located downstream of one another from an inlet port to first and second outlet ports (figures 4a-4f).

Description

DESCRIPTION

HEATING APPARATUS AND VALVE ASSEMBLY

The present Invention relates to heating apparatus and to valve assemblies which are particularly suitable for use in heating apparatus.

Decorative gas fires comprise a burner assembly covered with a layer of heat-resistant imitation fuel bed elements such as heat-resistant coal pieces, imaticn logs or pebbles. When gas is burnedv"at the burner assembly, the fuel bed elements are heated. The fuel bed elements glow and flames emerge from between the fuel bed elements, to provide a realistic simulation of a solid fuel fire or some other decor alive effect. it is desirable to be able to control the amount of combustion, both to regulate the heat output of the appliance and to control the visual appearance. For example, in some circumstances it may be desirable to produce visible flames from the fuel bed elements whereas in other circumstances it may be desirable to have fewer, or no flames and to have a glowing fuel bed. in other to assist in the control of the combustion, it is known to have a plurality of burners in the burner assembly, if both burners are fed with fuel at the same rate, then whilst it is possible to adjust the heat output, it is more difficult to control the appearance of the imitation fuel bed and the pattern of flames produced at the fuel bed. it would be possible to have a burner assembly formed from a plurality of separate burners, in which supply to each burner was controlled separately, but this would make it more difficult to control the appearance of the combustion. In addition, it would be necessary to provide separate controls for the two burners, which would increase the cost and complexity. in accordance with a first aspect of the present invention, a heating apparatus comprises a first and second burner means, and control means for controlling the supply of combustible fuei separately to the first and second burner means, wherein combustion of fuei at the first burner means is sufficient to ignite fuei supplied to the second burner means. in this way, whenever combustion takes piece at the first burner means, then if fuel is also supplied to the second burner means, it will also be ignited by virtue of the combustion of fuei at the first burner means.

Preferably, the control means is configured to suppiy fuei to the second burner means only if fuei is also supplied to the first burner means.

In this way, the pattern of flames and combustion can be controiied more accurately.

Preferably, each of the first and second burner means comprises a burner body and a plurality of apertures in the burner body at which fiames at produced on combustion fuei.

Preferably, each of the first and second burner means comprises one or more primary or main regions for combustion of fuei. in a preferred embodiment, the first burner means comprises a plurality of secondary apertures which are configured to produce flames at a location adjacent to the second burner means.

This helps to ensure that combustion at the first burner means also results in ignition of fuel supplied to the second burner means.

Preferably, the secondary apertures in the first burner means form a path leading from the primary combustion region.

Preferably, the secondary apertures in the first burner means lead to secondary apertures in the secondary burner means, which in turn leads to the primary combustion region of the second burner means

Preferably, each of the first and second burner means comprises an elongate primer/ or main region for combustion of fuel, and the primary combustion regions of the first and second burner means overlap each other.

This also ensures that combustion of fuel at the first burner means results in ignition supplied to the second burner means.

Preferably, one or both of the first and second burner means comprises a plurality of primary or main regions for combustion of fuel·

Preferably, the first and second burner means each comprise an elongate burner body. in accordance with a second aspect of the present invention, a valve assembly comprises a valve housing; an inlet port in the housing; first and second outlet ports in the housing; a flow path extending through the valve housing from the inlet port, to the first and second outlet ports; a first valve seat located upstream of the first and second outlet ports; a first valve closure member releasabiy engageahle with the first valve seat. a second valve seat located downstream of the first valve seat and upstream of the first and second outlet ports; a second valve closure member reieesably engageahle with the second valve seat; a third valve seat located between the second valve seat end the second outlet port; and a third valve closure member releesebly engageable with the th;rd valve seat.

By appropriate control of the valve assembly, It can be ensured that fuel can only be output to the second outlet port If ii Is also output to the first outlet port.

Preferably, the valve assembly further comprises a control rod extending out of the valve housing for determining the position of a second and third valve closure members.

The second and third valve closure members are preferably mounted on the control rod.

The second valve closure member may be slidably mounted on the control rod and the third valve closure member may be slidably mounted on the control rod.

The valve assembly may further comprise biasing means acting on opposite ends of the second valve closure member and/or the third valve closure member Preferably the biasing means is mounted on the control rod.

In a preferred embodiment, the control rod Is displaceable to lift the first valve closure member from the first valve seat.

In one embodiment, the fust valve closure member forms part of a solenoid actuated valve.

Preferably, the solenoid actuated valve Is configured to be held in the open position upon receipt of a signal from an oxygen depletion sensor.

The valve assembly may further comprise a third outlet port located downstream of the first valve seat and upstream of the second valve seat- This may, for example, provide a flow of fuel to a pilot burner If the first valve closure member is lifted from the first valve seat.

Preferably, the cross-sectional area of the third outlet port is smaller than the cross-sectional area of the first and second outlet ports.

The present Invention also includes a heating apparatus In accordance with the first aspect of the invention in combination with a valve assembly in accordance with the second aspect of the invention.

By way of example only, specific embodiments of the present invention wilt now be described, with reference to the accompanying drawings, in which:

Fig. 1 Is a perspective view of a first embodiment, of gas fire in accordance with the present invention, showing fuel bed elements partially removed;

Fig. 2 is a perspective view of a first embodiment of burner assembly in accordance with the present Invention, which is fitted to the fire of Fig. 1;

Fig. 3 is a plan view of the burner assembly of Rg. 2;

Figs, 4(a) to (f) are cross-sections! views through a control valve which forms part of the burner assembly of Fig. 2, shown in different positions;

Fig, 5 is a perspective view of a second embodiment of burner assembly in accordance with the present invention, which is a remote-controlled variant of the burner assembly of Fig 2; and

Fig, 6 is a plan view of the burner assembly of Fig. 5.

Referring firstly to Figs. 1 to 3, a gas fire 10 comprises a hollow housing indicated generally at 12, In the base of which a burner assembly 14 is located. The housing 12 is pressed from metal sheet and is generally cuboids! in shape. The housing 12 has a rectangular glass sheet 18 and a decorative trim 20 extends around the periphery of the aperture 18. The Interior wails of the housing are also provided with insulating panels 22.

As shown in Fig. 1, in use the burner assembly 14 is covered with a layer of heat-resistant imitation coal pieces 24 which are stacked to resemble a fuel beck but other fuel bed elements such as heat-resistant imitation logs or pebbles can be used if desired.

The fuel bed elements sit on top of the burner assembly 14 and when heated by the barrier assembly the elements glow and flames emerge from between the fuel bed elements, to provide a realistic simulation of a solid fuel fire.

The burner assembly 14 is shown in more detail in Figs. 2 and 3 and comprises a pressed metal tray 26 which is secured to the base of the housing 12, and on which the other components of the burner assembly are mounted. Front and rear elongate burners 28, 30 are secured adjacent to, and parallel to, each other by securing their ends to mounting brackets 32r 34 secured to the upper face of the tray 26.

Each burner 2S, 30 comprises a length of circular metal tube 32, 34, the two burners being of the same length. The tubes 32, 34 are located parallel to each other and are spaced apart by a short distance. The front burner 28 has a straight row 38 of slot-like outlet pods 40 formed in the uppermost facing portion of the wall of the tube 32, forming a main or primary region of combustion. The ports 40 are identical and the length of the row Is approximately naif the length of the tube 32 and located equidistant its two ends. A combustible gas/air mixture fed to the front burner £8 (as will he explained) is ignited at the ports 40 by means of a flame from a pilot burner P at the front of the tube and produces flames from the ports 40,

The rear burner 30 has two identical straight rows 42 of slot-like ports 44 (identical to the ports 40 of the front burner) formed in the uppermost facing portion of the wall of the tube 34, each forming a main or primary region of combustion. The length of each row 42 of ports is approximately one quarter the length of the tube 34 and they are located equidistantiy form the centre of the tube 34. The combustible gas/alr mixture fed to the rear burner is ignited (as will be explained), producing flames at the ports 44.

As best seen in Figs. 2 and 3. the tube 32 of the front burner is aiso provided with two parallel rows 46 of small circular ports, forming a secondary or supplementary region of combustion leading from the vicinity of the pilot burner P to the centre of the row 38 of ports 40 in the front burner. The combustible fuel/air mixture exiting from the ports of the two rows 46 of ports i§ therefore reliably lit by the pilot burner P: and the rows 46 of ports in turn ensure that the combustible fuel/air mixture exiting from the main row 38 of ports 40 in the front burner 28 Is reliably Ignited.

An identical pair of rows 48 of smell circular ports, forming a secondary or supplementary region of combustion, aligned with the first rows 48 also leads from the centre of the main row 38 of ports 44, The pair of parallel rows 48 of ports is in turn aligned will) an identical pair of parallel rows 50 of ports in the tube 34 of the rear burner 3, also forming a secondary or supplementary region of combustion, at its mid-point. The rows of ports 50 in turn intersect two parallel rows 52 of small circular ports extending between the inner ends of the two rows 42 of ports 44, also forming secondary or supplementary regions of combustion.

Whenever flames are present at the row 38 of ports 40 in the front burner, the combustible gas mixture exiting from the rows 48 of ports is also ignited. The flames emerging from the ports at the end of the rows 48 closer to the second burner 30 will project towards the ports in the aligned rows 50 of the ports in the aligned rows 50 of ports in the rear· burner 50. Consequently, if a combustible fuel/air mixture is supplied to the rear burner 30, ignition of fuel will take place along the rows 50 of ports, and from there to the row 52 of ports and from there to the two rows 42 of ports 44 in the rear burner 30.

Consequently, whenever fuel is supplied to the rear burner, as long as a flame is produced by the pilot burner F, ignition of the rear burner will aiso take piace, resulting from flames produced along the rows 48, 48 of ports in the front burner 28 and the rows of ports 50, 52 in the rear burner 30, it will also be observed that the ends of the row 38 of ports 40 in the front burner 28 overlap in the longitudinal direction with the inner end of each of the two rows 42 of ports 44 of the rear burner 30, as shown at “d::. Consequently, flames produced at the ends of the main row 38 of ports 44 will ignite combustible fuel/air mixture exiting from the rows 42 of ports 44 in the rear burner.

As wlH be explained below, the burner assembly is configured so that fuel can only be supplied to the rear burner 30 if it is slso supplied to the front burner 28, By virtue of the above arrangements, whenever fuel is supplied to the rear burner 30, it is ignited without the need for a separate pilot burner for the rear burner 30,

Fuel is supplied to the front and rear burners 28, 30 via an adjustable control valve 80. The control valve receives gaseous fuel at an inlet port 82 from e supply pipe 64. Fuel Is supplied to an injector 88 at one end of the front burner 28 from a first valve outlet port 88 through a first outlet, pipe 70 and is supplied to an injector 72 at the opposite end of the second burner 30 from a second valve port 74 through a second outlet pipe 76. As will be explained, the control valve 60 is configured so that fuel can only be supplied to the second burner 30 if it is also being supplied to the first burner 28. A pilot burner supply pipe 78 also branches off the outlet pipe 70 to the first burner, so that fuel is supplied to the pilot burner P whenever it Is supplied to the first burrser 28. in an alternative construction, fuel can be supplied from a separate dedicated output from the control valve, as will be explained.

The control valve 68 is adjusted by varying the position of a valve slide arm 80 which projects out of the control valve and is connected to a valve adjustment member 82 within the valve. The outer end of the valve slide arm 80 is pivotably connected to one end of a slide link arm 84. the other end of which is pivotally connected to a slide handle 86, which is pivotally mounted to the tray 28 at pivot 88. By manipulating the slide handle 88, the position of the valve slide arm can thereby he controlled in order to adjust the setting of the control valve 80.

An igniter unit 30 and batten/ 82 are mounted on the upper face of the control valve, to provide en igniting spark to the pilot burner P. A conventional oxygen depletion sensor (CDS) 94 is also mounted adjacent, to the pilot burner P so that, in the conventional manner, the fuel supply is cut off if the pilot flame is extinguished, or if the sensed oxygen concentration fails below a predetermined level.

The control valve 80 Is shown In mors detail In Fig, 4. The control valve comprises an elongate rectangular metal housing block 100 having a longitudinally-extending main bore 102 aligned with the longitudinal axis of the housing block 100 and passing through the block from one end to the other; The main bore 102 receives one end of the slide arm 80 which is slidably disposed in a cylindrical through aperture 106 in an end cap 108 which is screw-thneadediy received at one end of the main bore 102. The slide arm 80 is displaceable longitudinally within the main bore 1G2t as will be explained. A conventional electromagnetic cut-off valve 110 is secured in the opposite end of the main bore 102. The cut-off valve 110 has a valve ciosure head 112 which is displaceable between an actuated, withdrawn position shown in Figs. 4(b) to (f) and a tripped, extended position shown in Fig. 4(a). In the tripped, extended position of Fig. 4(a), the valve closure head is sealingly engaged with a first annuiar valve seat 114 formed by a shoulder of the main bore, and in the actuated, withdrawn position, shown in Fig. 4(b) to (f), the valve closure head 112 is displaced from the valve seat, in the actuated, withdrawn position, gaseous fuel Is allowed to flow to the pilot burner P and the main burners 28, 30, as will be explained, and in the tripped, extended position the flow of fuel to the burner assembly is prevented. The cut-off valve 110 is held in its actuated, withdrawn position by means of an electrical signal generated at the ODS 94 at the front burner 28, in the conventional manner, so that if the ODS senses that no combustion (or incomplete combustion) is taking place at the burner, the cut-off valve 110 will trip to the closed position shown in Fig. 4(a) and cut-off the supply of fuel to the burner assembly.

The housing block 110 is provided with a gas inlet port 118. first and second main outlet ports 118, 120 and an optional pilot outlet port 122 on one sins face, all of which are locatsd downstream cf the first valve seat 114. Each of the ports communicates with the main bore 102 by means of a respective transverse passage 124, 126, 128,130. In addition, a gas supply bore 134, extends through the housing block 100 parallel to the mein bore, and communicates with the main inlet port 116 via a transverse passage 136 and with the first valve seat 114 of the cut-off valve 110 via a transverse passage 138.

The slide arm BO has a main portion 142 of a first, larger diameter which passes out of the valve through the end cap 108, and an end portion 144 of smaller diameter which is located within the control valve 80, A first, smaller cylindrical valve closure head 148 is slidably mounted on the smaller diameter portion 144 and is reieasabiy and sealingiy engageable with a second annular valve seat 148 formed by a shoulder portion of the main here 102 adjacent to the first outlet port 118, located downstream of the first valve seat 114 and upstream of the first and second main outlet ports 118, 120. The head 148 is urged towards the end of the smaller diameter portion 144 by a compression spring 149 mounted on the portion 144, the inner end of the spring engaging a circlip 150 on the valve rod. The displacement of the first valve closure head 148 towards the end of the smaller diameter portion 144 is limited by a further circlip 152 on the valve rod. A further compression spring 154 is mounted on the end of the smaller diameter portion 144, for engagement with the cut-off valve 110, as will be explained. A second, larger cylindrical valve closure head 155, of larger diameter than the head 148, is slidably mounted on the smaller diameter portion 144 of the slide arm 80. the second valve closure head 158 Is slidably and sealingiy mounted in an enlarged diameter portion 158 of the main bore 102.. A compression spring 160 mounted on the smaller diameter portion 144 extends between the outer face of the head 156 and a shoulder 182 formed at the junction of the main portion 142 and the smaller diameter portion 144 of the slide arm 80. The compression spring 148 which is engageable with the first smaller valve closure head 148 can also abut the opposite end face of the larger valve closure head 158 in certain positions of the slide arm 80, as will be explained.

The larger valve closure head 158 is reieasabiy and sealingiy enoageable with a third annular valve seat 184 formed by a further shoulder portion of the main bore 102 adjacent to the second output port 120, located between the second valve seat 148 and the second main outlet port 120, l.e. downstream of the second valve seat 148 and upstream of the second main outlet port 120. As will be explained, the second valve closure head 158 can also be displaced to the position shown in Fig, 4(f), In which the transverse passage 124 connecting the gas inlet pert 118 and the gas supply bore 134 is partially dosed.

Hie control valve 60 is adjusted between the configurations illustrated in Figs, 4{a) to 4(f) by varying the position of the slide handle 86, which in turn controls the position of the valve slide arm 80.

In the configuration shown in Fig. 4(a), the slide handle 86 is pivoted ίο the right (to the position shown in Fig, 1) to its maximum extent, which causes the vaive siide arm 80 to be withdrawn from the control valve 80 to its maximum extent, as governed by engagement of a circlip 168 mounted on the main portion 142 of the slide arm with the inner face of the end cap 108,

In this position, the smaller valve closure head 146 is also withdrawn from the second vaive seat 148 to the maximum extent and the compression spring 149 urges the larger ciosure head 158 into the position shown in Fig. 4(a) in which gas fed through the input port 118 is prevented from entering the gas supply bore .::5::1::84 via the transverse bore 136. The supply of gas to the valve is therefore completely cut-off, and as a result no flame can be produced at the ODS 94, which causes the cut-off valve 110 to trip to its closed position, in which the valve head 112 is in engagement with the first vaive seat 114, as shown in Fig. 4(a).

When it is desired to light the appliance, the slide handle 86 Is pivoted to the left to its maximum extent, which causes the vaive slide arm 80 to be displaced inwardly to its maximum extent, as shown in Fig. 4(b). This causes the and of the main portion 142 of the slide arm 80 to engage the adjacent end face of the larger valve closure head 156 and to displace the head 158 inwardly, into engagement with the third valve seat 164. it also causes the smaller valve closure head 146 to engage with the second valve seat 148 and also displaces the valve closure member 112 of the cut-off valve 110 from the first vaive seat 114.

As a result, gas is allowed to flow from the inlet 118 through the gas supply bore 134 via the transverse bore 136 to the transverse bore 138. This permits gas to flow to the pilot burner P via the pilot outlet port 122, but gas Is prevented from exiting the main outlets 118, 120 as a result of the engagement of the smaller valve closure head 148 with its vaive seat 148. Holding open the cut-off vaive 110 also activates the igniter, which causes gas fed to the pilot burner P fo ignite. This in turn heats the ODS 94 and once the DOS 94 is at an operating temperature, the slide handle 86 can be released. The signal from the ODS 94 then holds the cut-off valve 110 open end the springs mounted on the valve slide arm 80 cause the slide arm to be slightly withdrawn from its maximum inward position. This causes the smaller valve closure head 148 to be lifted from its valve seat 148 and allows gas to flow through the first outlet port 118, This supplies gas to the front burner 28, which is then ignited by the pilot burner P as described previously.

Moving the slide handle 88 slightly mors fo the right causes the valve slide arm 80 to be further withdrawn, which withdraws the smaller valve closure head 146 further, completely opening the first main outlet pod 118. in this position, as shown in Fig. 4(d), the gas is supplied to the pilot burner P and the front burner 28 is supplied with gas to Its maximum extent. As will be seen from Fig. 4(d), in this position the larger valve closure head 156 remains in engagement with its valve seat 158. preventing gas from being supplied to the rear burner 30 via the second main outlet port 120.

Further movement of the slide handle 88 to the right further withdraws the valve slide arm 8Q. The spring 149 is then urged by the smaller valve closure head 148 against, the inner face of the larger valve closure head 158, and causes the larger valve closure head 156 to be lifted front its valve seat 158, into the position shown in Fig. 4(e), This results in a supply of gas to the rear burner 30, in addition to the full supply of gas fo the front burner 28. As described previously, the dames generated at the front burner 28 ensure that gas supplied to the rear burner 30 is ignited.

Further movement of the slide handle 88 to the right causes the larger valve closure head 1S8 to be completely withdrawn from the transfer port 128 leading to the second main outlet port 120, as shown in Fig. 4(f). In this position, the maximum supply of gas is fed to both the first and second main output ports 118, 120.

In this way, the supply of gas to the front and/or rear burners can be controlled However, it is important to note that gas can only be supplied to the rear burner 30 if it is also supplied to the front burner 28, in the above description, fuel is supplied to the pilot burner P via the optional outlet ροή 122. if the pilot outlet ροή is not used, fuei can instead be supplied to the pilot burner P via the main outlet port 118 and a pilot burner supply pipe 78 branched off the outlet pipe 70 to the first burner 28 (see Figs. 2 and 3). A second embodiment of burner assembly in accordance with the present invention, which can be used in place of the burner assembly 14 of the first embodiment, is illustrated in Figs. 5 and 8. in the following description, features of the second embodiment which correspond to features of the first embodiment are identified with the same reference numeral as in the first embodiment, with the additional of a prime (‘),

The second embodiment is a remotely-controlled variant of the first embodiment, in practice, the burner assembly will be controlled by means of a contactless control (such as an infrared control). This will require the use of an appropriate sensor and controlling circuits, which will be known to those skilled in the ad and v^hich have been omitted from Figs. 5 and 8, for the purposes of simplicity and clarity.

The burner assembly 14’ comprises a tray 26’ which ;s secured to the base of the housing 12, and on which the other components of the burner assembly are mounted. Front and rear elongate burners 28', 30’ (identical to the front and rear elongate burners 28, 30 of the first embodiment) are secured adjacent to, and parallel to, each other by securing their ends to mounting brackets 32’, 34’ secured to the upper face of the tray 28!, As in the first embodiment, a combustible fuei/asr mixture exiting from the ports of the two rows 48' of pods in the front burner 28' is lit by a pilot burner 8’.

The adjustable control valve 60 and the slide handle 88 of the first embodiment are omitted. Instead, gaseous fuei is supplied from a supply pipe 84' to a remotely-operated solenoid-actuated control valve 180 mounted at the rear of the tray 28’, The control valve 180 has a first, pilot outlet 184 which supplies gaseous fuel to the pilot burner 8’ via supply pipe 186. The control valve 180 also has a second, main outlet port 188 which supplies gaseous fuel to an injector 86’ at one end of the front burner 28 through an outlet pipe 70'. A supply pipe 76' branches from the outlet pipe 70' and Is connected, via a remotely operated solenoid-controlled valve 190 to an injector 72' at the opposite end of the rear burner 30’.

The control valve 180 Is operable to (a) close off the supply of gas to the pilot outlet port 184 and the main outlet port 188, (b) supply gas to the outlet port 184 but not to the main outlet pod 188, (c) supply gas to the pilot outlet port 184 and to supply gas to the main outlet port 188 below the maximum rate or (d) supply gas to the pilot outlet 184 and to supply gas to the main outlet port 188 at the maximum rate. In this way, the gas supplied to the front burner can be controlled.

Whenever gas flows through the first outlet pipe 70’ from the main outlet pod 188, it is also fed to the second control valve 190. which controls the flow of gas to the rear burner 30’. The second control valve 190 can be adjusted between its two extreme positions of shutting off the flow' of gas to the injector 72’ of the rear burner 30’ or to open fully to provide maximum flow of gas to the injector 72’ of the rear burner 30’. The flow of fuel to the rear burner 30' can therefore be controlled as desired.

As in the first embodiment, gaseous fuel can only be supplied to the rear burner 30’ if It is also being supplied to the front burner 28’.

The burner assembly shown In Figs. 5 and 8 can be fitted info the housing 12 shown in Fig, 1 and other than the control of gas to the front and rear burners 28’, 30’, operates identically to the first embodiment.

The invention is not restricted to the details of the foregoing embodiments.

For example, more than two burners (e.g. three, four or more burners) may be provided, wherein combustion of fuel at the first burner is also sufficient to Ignite fuel supplied to the further burners.

Claims

Claims

1. A heating apparatus comprising first and second burner means, and control means for controlling the supply of combustible fuel separately to the first and second burner means, wherein combustion of fuel at the first burner means is sufficient to ignite fuel supplied to the second burner means.
2. A beating apparatus as claimed in claim 1, wherein the control means is configured to supply fuel to the second burner means only if fuel is also supplied to the first burner means,
3. A heating apparatus as claimed in claim 1 or claim 2, wherein each of the first and second burner means comprises a burner body and a plurality of apertures in the burner body at which flames are produced on combustion of fuel.
4. A heating apparatus as claimed in any of the preceding claims, wherein each of the first and second burner means comprises one or more primary of main regions for combustion of fuel.
5. A heating apparatus as claimed in claim 4, wherein the first burner means comprises a plurality of secondary apertures which are configured to produce flames at a location adjacent to the second burner means.
8. A heating apparatus as claimed in claim 5, wherein the secondary apertures in the first burner means form a path leading from the primary combustion region.

7. A heating apparatus as claimed in claim 5 or claim 8, wherein the secondary apertures in the first burner means lead to secondary apertures in the secondary burner means, which in turn lead to the primary combustion region of the second burner means.

8. A heating apparatus as claimed in any of claims 4 to 7, wherein each of the first and second burner means comprises an elongate primary or main region for combustion of fuel, the primary combustion regions of the first and second burner means overlapping each other.

8, A heating apparatus as claimed in any of claims 4 ίο 8, wherein one or both of the first and second burner means comprises a plurality of primary or main regions for combustion of fuel
10. A heating apparatus as claimed in any of the preceding claims, wherein the first and second burner means each comprise an elongate burner body
11. A valve assembly comprising; a valve housing; an inlet port in the housing; first and second outlet pods in the housing; a flow path extending through the valve housing from the inlet port to the first and second outlet ports; a first valve seat located upstream of the first and second outlet ports: a first valve closure member reieasabiy engagsabie with the first valve seat; a second valve seat located downstream of the first valve seat and upstream of the first and second outlet ports; a second valve closure member reieasabiy engagsabie with the second valve seat; a third valve seat located between the second valve seat and the second outlet port; and a third valve closure member reieasabiy engageable with the third valve seat.
12. A valve assembly as claimed in claim 11, further comprising a control rod extending out of the valve housing for determining the position of the second and third valve closure members:
13. A valve assembly as claimed In claim 12; wherein the second and third valve closure members are mounted on the control rod
14. A valve assembly as claimed In claim 13; wherein the second valve closure member Is slidably mounted on the control rod;
15. A valve assembly as claimed in claim 13 or claim 14, wherein the third valve closure member is slidably mounted on the control rod.
16. A valve assembly as claimed in claim 15, comprising biasing means acting on opposite ends or the second valve closure member and/or the third valve closure member.
17. A valve assembly as claimed in claim 16, wherein the biasing means comprise a spring.
18. A valve assembly as claimed in claim 16 or claim 17. wherein the biasing means is mounted on the control rod,
19. A valve assembly as claimed in any of claims 12 to 18, wherein the control rod is displaceable to lift the first valve closure member from the first valve seat,
20. A valve assembly as claimed in claim 19, wherein the first valve closure member forms part of a soienpld actuated valve.
21. A valve assembly as claimed in claim 20. wherein the solenoid actuated valve is configured to be held In the open position upon receipt of a signal from an oxygen depletion sensor.
22.. A valve assembly as claimed In any of claims 11 to 21, composing a third outlet port located downstream of the first valve seat and upstream of the second valve seat.
23. A valve assembly as claimed In claim 22, wherein the cross-sectional area of the third outlet port is smaller than the cross-sectional areas of the first and second outlet ports.
24. A heating apparatus substantially as herein described with reference to, and as illustrated in, the accompanying drawings,
25. A valve assembly substantially as herein described with reference to, and as illustrated in, Fig. 4 of the accompanying drawings.
26. A heating apparatus as claimed in any of claims 1 to 10 and 24 in combination with a valve assembly in accordance with any of claims 11 to 23 and 25,