GB2473739A

GB2473739A - Solid fuel firebed

Info

Publication number: GB2473739A
Application number: GB1015607A
Authority: GB
Inventors: Frederick Frank Waghorn
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-09-17
Filing date: 2010-09-17
Publication date: 2011-03-23
Anticipated expiration: 2030-09-17
Also published as: GB201015607D0; GB0916298D0; GB2473739B; GB201004830D0

Abstract

Solid fuel heating apparatus (e.g. a fireplace, cooker or stove) has a firebed comprising a base 11 and an air funnel 19 comprising an aperture through the base and a plate supported adjacent or in the aperture so that in use air flows laterally across the base. The plate may be a V-shaped fuel cradle (23, fig 1), or it can be horizontal, supported on legs (46, figs 5A-D) and adjustable in height. One embodiment (figs 7A-I) has three V-shaped fuel support plates. An adaptor (50, figs 6A and 6B) with wings may sit on the plate and direct air into the ash. The adaptor may suspend fuel on spacers (85, fig 16). Air can pass through a back cavity (73, fig 10) to feed the top of the flames.

Description

Improvements in or Relating to Solid Fuel Heating Apparatus The present invention relates to improvements in or relating to solid fuel heating apparatus in particular a firebed for a solid-fuel fireplace or stove. More particularly, the present invention relates to a firebed comprising an air-funnel.

Typical fireplaces and stoves include a fire basket or firegrate within or upon which the fuel is located, above the base of the fireplace or stove. The firegrate or basket helps to provide an even distribution of air throughout the fire by allowing air to circulate around the burning fuel. This reduces the amount of smoke produced and increases efficiency.

However, existing wood-burning and multi-fuel stoves are known to suffer from incomplete combustion. This is particularly problematic in the region of the fire base, at the heart of the fire and also at the back of the fire within the stove. As a consequence of incomplete combustion, the fire produces more smoke and higher carbon emissions, and is less fuel-efficient.

In fireplaces and stoves which include a firegrate, the flow of air through and around the burning fuel is substantially uniform and cannot easily be regulated or directed to the core parts of the fire, such as towards the rear and through its centre. A further problem arises once the fire has been burning for some time and ash starts to build up as there is a tendency for it to collect and congeal within the apertures of the grate, and to disrupt the flow of air to further exacerbate the problem.

In an attempt to increase combustion efficiency, secondary burn systems have been introduced. Such systems provide a flow of air above the burning fuel, typically in a substantially horizontally flow. This introduces a fresh supply of oxygen to any unburnt resinous vapours within the flame enabling combustion from the flames below. However, these secondary burn systems have the effect of reducing the stove and flue temperature, due to an airflow that only spasmodically feeds the resinous vapour and flame simultaneously. Accordingly, such systems typically tend to be less thermally efficient.

Pre-heated and non pre-heated air-wash systems which direct air flows over the inner face of the glass window within the stove door, or the glass front of a fire, are also known. These systems act to discourage resinous particles, emitted during burning, from sticking to the glass window and thereby assist their combustion within the fire.

This results in a simultaneous heating and cooling of the window surface, which causes a substantial fluctuation in the temperature of the glass window, and which reduces the thermal output efficiency of the fire.

In addition, stoves and fireplaces which include several different air controls also tend to reduce the thermal efficiency of the stoves, resulting in higher emissions into both flue pipes and the atmosphere.

US 4,881,522 discloses a hearth having an air supply means in its base, a metal dish arranged at a predetermined height above the base and defining an area for preheating combustion air which then flows upwardly around the contour of the dish to form a curtain of preheated air. Also described is an optional belt which surrounds the dish, with a continuous gap therebetween, to define an air-inlet slot. The described method comprises introducing combustion air into the hearth in the form of a continuous stream to form a constant ascending air curtain laterally surrounding the glowing embers in the hearth.

However, the fire arrangement described in U5 4,881,522 tends to result in an incomplete combustion of the fuel since only the outer parts of the fire are fed properly with oxygen from the air curtain, and the centre of the fire is substantially deprived of the levels of oxygen required to achieve this.

In addition, fires of this kind tend to be more difficult to light, and suffer from a reduction in the temperature of the stove and flue as a result of air being drawn away from the fire and directly into the flue.

The present invention seeks to overcome at least some of these disadvantages and provide a firebed which results in a more efficient combustion of a solid fuel.

In a first aspect, the present invention provides a firebed for a solid fuel heating apparatus, the firebed comprising a firebed base and an air funnel associated with the base, wherein the air funnel comprises an aperture through the base said aperture having a peripheral edge, and an air funnel plate supported adjacent the aperture and spaced therefrom such that the air funnel, in use, produces a substantially lateral air flow across the firebed base.

Suitably, at least a part of the air funnel plate is adjustable for height. Optionally, the fuel cradle is adapted to be tiltable or removeable.

In a first embodiment, the aperture and air funnel plate are correspondingly elongate.

Suitably, the air funnel plate has a V-shaped cross-section to form a cradle.

Preferably, the firebed base comprises a pair of elongate plates held in a spaced configuration defining the aperture therebetween.

Preferably, the firebed further comprises an air funnel plate adaptor supportable by the air funnel plate to modify air flow through the air-funnel.

Suitably, the air funnel plate adaptor is substantially W-or M-shaped, and complementary in shape to the air funnel plate.

Suitably, the air funnel plate adaptor further comprises a series of aeration holes or slots in regions which do not overlay the air funnel plate. Preferably, the series of aeration holes or slots are shrouded to prevent their blockage.

In a second embodiment, the air funnel is defined by an air funnel plate formed as a substantially flat plate and a cylindrical member between the aperture and the air funnel plate, to an upper end of which cylindrical member the plate is axially mounted with a space therebetween.

Suitably, the substantially flat plate is coupled to the cylindrical member, advantageously by welding.

Preferably, the space between the plate and cylindrical member is between 1 and 5mm; more preferably between 1 and 3mm and most preferably about 2mm.

In a second aspect, the present invention provides a solid fuel heating apparatus comprising a firebed as defined above.

Preferably, the heating apparatus includes a cavity below the firebed.

Suitably, the cavity forms a cooking cavity.

In a third aspect, the present invention provides a solid fuel heating apparatus comprising a firebed as defined above and further comprising a combustion chamber having, at a rear or side face thereof, a cavity plate spaced from said face to define a cavity therebetween and having a lower edge spaced from the firebed to define an aperture therebetween.

Preferably, the apparatus further comprises a heat-exchanging apparatus within the cavity, the heat exchanging apparatus being fluidly coupable to an external space-heating apparatus.

The above and other aspects of the present invention will now be illustrated in further detail, by way of example only, with reference to the accompanying drawings in which:

S

Figures 1A to 1C are perspective, schematic side and top plan views respectively, of a firebed insert in accordance with the first aspect of the invention; S Figure 2 is a schematic side view of a first embodiment of a stove in accordance with the second aspect of the invention; Figure 3 is a schematic side view of the embodiment of Figure 2 in which a flow of air through the embodiment, in use, is illustrated; Figure 4 is a schematic side view of an embodiment of an open fireplace comprising an integral firebed, in accordance with the second aspect of the invention; Figures 5A & SB are sectional side and schematic top plan views, respectively, of an alternative embodiment of a firebed in accordance with the first aspect of the invention; Figure SC is a schematic side sectional view of a modification of the embodiment of Figure SA applied as a modification to an existing firebed; Figure SD is a sectional view of a further modification of the embodiment of Figure SA; 2S Figures 6A & 6B are perspective and schematic side views, respectively, of a fuel cradle adapter for use with a firebed in accordance with the first aspect of the invention; Figures 7A to 71 are schematic side views of a second embodiment of a firebed insert in accordance with the first aspect of the invention; and Figures 8 to 15 are schematic sectional views of various embodiments of a cooking apparatus in accordance with the present invention.

Referring to Figures 1A to 1C there is shown a firebed 21 formed with a substantially V-shaped air funnel plate forming a fuel cradle 23 which is supported within a firebed base 24. Base 24 is formed from a pair of end-plates 25, which define first and second ends, and which are connected in a spaced configuration by a pair of longitudinal plates 30 spaced with respect to each other to define a rectangular opening 31 therebetween (Figure ic). An inner surface of each end plate 25, in the region of opening 31, includes a bracket 32 to support the fuel cradle 23 in its operative position. In use, the fuel cradle and longitudinal plates support the fuel to be burned. In alternative embodiments (not shown), the housing end-plates are omitted such that the first and second ends of the firebed are open', the components being supported by a simple frame construction.

In preferred embodiments, the fuel cradle 23 is removable to allow ash from a spent fire to be brushed through rectangular opening 31 and into an ash tray or pan located below for the purposes of cleaning (shown in Figure 4).

Referring to Figure 1B, the V-shaped fuel cradle 23 is shown mounted upon firebed housing 24. As can be seen, the base 24 and fuel cradle 23 are mounted in a manner which maintains a gap 33 thereby forming an air funnel 19 (see airflow arrows in Figure 2 between the outer edges on each side of the fuel cradle 23, and inner edges of rectangular opening 31 of base 24). In use, the air funnel thus acts to funnel air through the heart of the fire. The gap is typically between 1-5mm and is preferably 1-2 mm.

In preferred embodiments (not shown), the air funnel plate is adjustable for height relative to the firebed housing. This permits the flow of air through the firebed and fire to be controlled and adjusted.

In further preferred embodiments (not shown), the fuel cradle is tiltable to allow any ash contained therein to be emptied into an ash pan located below the firebed, in use.

In alternative embodiments, the firebed may include a plurality of parallel fuel cradles and thereby associated air funnels. Figure 7 shows three such cradles. Preferably, each fuel cradle is adjustable for height relative to one another.

In alternative embodiments, such as that shown in Figure 6 the fuel cradle is substantially W-or M-shaped.

Referring to Figure 2 there is shown a stove 10 comprising a base 11, above which is located a firegrate 12 and a combustion chamber 13. The stove also includes a throat plate 14, an exhaust flue 15, and a glass-fronted door 20.

The illustrated embodiment includes a firebed insert 21 is positioned centrally upon firegrate 12. In this arrangement, the firegrate openings have been closed except in the region immediately below the fuel cradle (not shown). The base 11 includes an adjustable air-intake 22, and an ash pan (not shown) for the collection of ash from a spent fire.

The firebed arrangement has the effect of forcing all of the air entering the stove, in use, through the adjustable air-intake 22, under the firegrate 12, through the substantially horizontal air funnels 19 of firebed 21 and to the core of the fire.

With the door closed, the heat of the fire draws air towards and up the flue 15, whilst at the same time accelerating the rate at which replacement air (and oxygen) is drawn through the adjustable air-intake 22 and air funnels 19 of the firegrate. This results in an increase in the efficiency of combustion and also in the thermal output of the fire.

Control of the flame and the rate of burn can be achieved through adjustment of the air-intake control 22 in a conventional manner.

In alternative embodiments, the firebed is formed integrally as part of a new stove construction, without the requirement of a firegrate or, if the firegrate is removable, can be supported in place by the firegrate supports, again avoiding the need to use a firegrate.

It is preferred, in use, that all airwash and secondary bum inlets are adjusted to support adjustable air-intake 22.

Referring now to Figure 3, there is shown a schematic representation of the airflow through the stove of Figure 2. From preliminary results, it has been shown that the air speed (B) through adjustable primary air intake 22 is around ten times greater than the air speed (A) through flue 15 when not contaminated by secondary airfiows through vents (X) and (Y). In addition, the speed of airflows (C) and (D), through air funnel 19 and an optional air brake 35 respectively, has been calibrated to be 50% greater than the flue air flow (A), although this is likely to vary depending upon the size of the air funnel 19, and also the extent to which the adjustable air-intake 22 is opened together with vents (X) and (Y) intake.

Airbrake 35 is optional and, in many situations greater advantages are achieved by use of the firebed of the present invention if no air brake is provided or if the space forming the air brake is obstructed or adjusted.

The extent and speed of the funnelled air streams (C) through air funnel 19 are adjustable through the bum by adjustment of the height of the funnel opening.

The speed of the airflow (B) through the adjustable air intake opening that feeds air into the chamber below the firebed is typically seven times greater than that of the airflow (C) leaving the same chamber that feeds the fire from the air funnel and the flow of air (D) through air brake 35. High speed air turbulence which is generated from air entering the bottom air chamber through the air intake 22 also assists in keeping the air funnel free from debris.

In the illustrated embodiment, around 30% of air is forced through the air funnel 19, and 10% of air is released through the air brake 35 to provide an airflow (E) to feed the front face of the fire. Accordingly, the air is forced horizontally through the flames and embers of the fire whilst being supported by a smaller secondary air flow over its front face. Pressure of the air flow is reduced by secondary air entering the chamber by means of (X) and (Y).

In Figure 4 there is shown an open fronted fire 40, formed from a convector box 41, and including a firebed 42 in accordance with the invention. As with the stoves described above, in use, air above the fire flows in an upward direction with the rising heat, and cooler air below the fire is drawn through the funnel creating both horizontal and diagonal draughts within the fires core forcing combustion. Although the illustrated fire is formed from a convector box, the firebed is suitable for use with any open fire having a flue.

As will be appreciated from an observation of the airfiows illustrated in Figures 2 to 4, the V-shaped cross-section to fuel cradle 23 provides an airflow directed in a generally lateral direction away from the cradle. This arrangement acts to move ash away from the ventilation gap 33 between the cradle and its support thereby preventing ash from blocking air gap 33 or falling into the cavity below the firebed.

This is particularly advantageous as will become apparent below in developing a conventional fire construction into a basic oven. Additionally, the ash is moved by the airflows to form an insulating bed of ash, enhancing the heat uniformity in the cavity below the firebed.

An alternative firebed design is illustrated in Figures 5A and SB in which an air funnel 43 comprises a substantially circular flat air funnel plate 44 which is supported on legs 46, and which forms therebetween a corresponding cylindrical element 45. In this alternative arrangement, an airflow through the firebed will exit the air funnel 43 in a substantially horizontal manner.

The air funnel plate 44 is adjustable for height by the addition or removal of spacers 47, upon which outer leg 46 rests. This arrangement permits the firebed to be used with a variety of solid friels, in which the height of the air funnel plate is adjusted to prevent a particular fuel from falling into and blocking air ftinnel 43. In alternative S embodiments, the legs are replaced with tubular plates which are meshed or which include air-holes or vents.

The firebed may comprise any number of air funnels 43 depending upon its size. As can be seen in the exemplary plan view of Figure SB, the firebed 43 has a pair of air funnels 43. In ftirther alternative embodiments, the air ftinnel plate and cylinder are non-circular.

Figure SC shows this arrangement applied to an existing firebed formed of fire grate bars 110. A closure plate 111 is placed over bars 110 to close airfiows through the bars except as now described. Additional seals 112 may be provided between grate bars 110 to ensure complete seating. Closure plate 111 has an aperture 113 formed within it to provide a support for an air funnel 43 of the type described above.

Suitably, the air frmnnel 43 includes a base 114 receivable in a base plate 115 mountable within aperture 113. By this arrangement, a relatively small air ftinnel 43 can be mounted in a relatively large aperture 113 to make for easy clearing of the firebed.

Figure SD shows a further variation to air funnel 43 of Figure SA in which the ftinnel is adjustable for height above the firebed by being formed of outer and inner telescoping cylindrical portions 120, 121 adjustably by means of cooperating threaded portions 122, 123. Adjustability allows an optimum balance between volume and speed through the air funnel and the secondary air and air-wash systems to be determined for any particular stove in order to give minimum carbon monoxide discharge. Suitably the spacing between cradle plate 44 and cylindrical element 45, that is to say, the height of the air funnel outlet apertures, (reference d in Figure SD), is selected to be in the range of 1-5mm; preferably 1-3mm; and more preferably about 2mm. This arrangement provides that around 30-50% of the airflow through the stove drawn by the flue passes through the air funnel, the remainder being fed by air wash and secondary air fed above the flames of the fire. With such an arrangement, the fire is seen to burn brightly, with small, clean flames, with low carbon monoxide emissions, and with high conversion of combustible material to ash.

The air funnel also allows low volumes of single-layered wood or multifuel to be burned over a solid ash base, thereby minimising the amount of fuel burnt at any one time, by spreading air horizontally at a low level throughout the combustion chamber. It has been found that many stoves sized to fit aesthetically within modern-day homes have too large a heating capacity. The present invention, whether installed in a new heater or whether added retrospectively to an existing heater overcomes this problem.

In Figures 6A and 6B there is shown an M-shaped adapter 50 for a firebed. The adapter is designed for use with substantially V-shaped air funnel plates, as described above. The adapter 50 is complimentary in shape to air funnel plate 23 and includes wings 51 which overhang the edges of the air funnel plate. Wings 51 act to modify the flow of air through the firebed funnel and also prevent ash and fuel from dropping into and creating an obstruction in the air funnel. In addition, the wings 51 divert a portion of the air flow downwards into the ash base. The resulting downward draft feeds oxygen into the glowing ash base and embers, increasing the ash temperature and incinerating un-burnt particles As shown in Figure 6A, wings 51 comprise a series of vents 52 through which a portion of the airflow through funnel 19 passes in use. The vents help to distribute the air entering through air-intake 22 to the core of the fire. As shown, it is preferred that wings 51 extend beyond the side plates 25 of the firebed to prevent ash contamination to a cooking fray in the ash pan area.

The height of end-plates 25 and the angle of inclination of adaptor wings 51 can be varied from product to product. A more acute wing angle enables the provision of a deeper ash reservoir without contamination of gaps 33 and vents 52.

Figures 7A to 71 show a number of firebed configurations for a firebed which comprises three air funnel plates. As illustrated in Figures 7A to 71, each air funnel plate is independently adjustable for height. This arrangement allows for a number of different firebed arrangements, with many configurations of horizontal airfiows from the fires core, enabling optimum burn from any combination of fuels burnt. The relative positioning of each air funnel plate will depend upon the fuel type that is to be burnt, and the air funnel plates will be configured provide the most efficient combustion of the particular fuel being used.

Inclusion of an air funnel 43 in accordance with the present invention in an oven is illustrated schematically in Figure 8. As described above, since the air funnel 19, 43, acts to draw ash away from the aperture in the firebed, the cavity below the firebed remains clear of ash. Accordingly, the air funnel allows the cavity to be used as an oven with the base of the firebed acting as a radiant panel for the oven cavity. The construction is substantially as shown in Figure 8 in which the air break 35 has been closed by means of a door seal 60. The product 61 to be cooked is placed below the firebed in a cooking tray 62 placed within the ash pan 63. The cooking tray may be open, as shown, or may be a sealed, vented tray to ensure that ash contamination is avoided or for foods such as casseroles. In use, cooking heat 64 radiates downwardly from the firebed (there being no separate grate 12, unless the air funnel has been installed in an existing stove) through fresh turbulent air from intake 22. Cooking vapours pass through the air funnel to the flue avoiding emission of odours to the room.

The forced air induction from the centre core of the fire into the flames of the fire throws intense heat and flame onto and into the side, rear and front sections of the stove, boiler, cooker or convector. The level of forced heat transfer to the bottom of the fire chamber walls burning with maximum heat enables maximum heat exchange to the room and to the boiler or base radiant panel for cooking below, where present.

An alternative construction is shown in Figure 9. A supplementary air supply 65 is provided from the top, sides, front or rear of the oven which, on passing through the oven to the oven chamber is preheated. Adjustment of the relative proportions of preheated air 65 and fresh air from intake 22 by respective controls 70,7 1 allows adjustment of the oven temperature. A thermostat 72 provides an indication of temperature. In certain embodiments, controls 70,71 are controlled electrically by a circuit including thermostat 72.

Figure 10 shows a further embodiment of a stove in accordance with the present invention in the form of an oven. The oven is substantially as described above, with corresponding reference numerals, with the following additions. At the back of the combustion chamber is a cavity 73 defined by a cavity plate 74 spaced from the rear wall 75 of the stove. Cavity plate 74 is spaced at its bottom edge from the firebed and at its top edge from throat plate 14. In use, air flows upwardly through the firebed 21 where it is directed by M-shaped adaptor 50 downwardly across longitudinal plates 30 (or, where adaptor 50 is omitted, by an air-jet through gap 33) where a proportion then passes up cavity 73 where it is returned to the combustion chamber 13 causing cleansing of combustion (enhanced oxidation of carbon monoxide to carbon dioxide) by products by increasing the temperature in that region. In the preferred arrangement of this embodiment, a small proportion of air is allowed to pass through a gap 76 between throat plate 14 and the rear of the stove. This induces an improved air flow through the cavity and flame along the firebed 21.

In a modification, throat plate 14 can be adjusted to a near-closed position to the top of the stove and outlet 76 correspondingly increased in size such that a reduced cavity at the top of plate 74 forces most combustion products upwards through cavity 73.

The air funnel directs a proportion of the air across the firebed, where it is then directed up cavity 73. Additional control to the cavity is by use of secondary air.

Figure 11 shows modification of the ovenlstove illustrated in Figure 9. As with the embodiment of Figure 10, a cavity 73 is formed between a cavity plate 74 and rear wall 75 of the stove. However, cavity 73 is linked at its lower edge to a base cavity 80 passing underneath the base of the stove. Cold or fresh air from the room enters base cavity 80 and passes up rear cavity 73 and over the top of the oven through a top cavity 81 before passing down the front of the stove into the oven chamber as pre-heated air. The induced air flows thus generated improve the efficiency of the convection flows by increasing the speed of air around the stove.

In the preferred arrangements, the top cavity 81 includes a control flap 82, adjustment of which allows a proportion of the pre-heated air to pass into the room to act as a space heater.

Figures 12 to 15 illustrate the application of the arrangements of Figures 10 and 11 to water heating boilers, in combination with a cooking oven capability. In Figure 12, cavity plate 74 of Figure 10 is replaced by a heat exchanger 82 operatively coupled to a water circuit, such as that of a central heating system. In the embodiment of Figure 13, a further heat-exchanger 84 is provided adjacent the rear wall such that cavity 73 is formed between two heat exchangers, thereby increasing the heat transfer to the water. Corresponding arrangements are shown in Figures 14 and 15 in which the gap 76 is replaced by an adjustable damper control 83 to provide a greater degree of control over the balance between space heating and water heating. Both the cavity and the fire chamber may be supported by secondary air.

Figure 16 shows a further modification to the air funnel device described above. A plurality of metal lifting spacers 85 are provided along at least the top edge of M-shaped adaptor 15 (or air funnel plate 23).

Metal lifting spacers 85 are typically about 10mm in height and act to suspend burning fuel above the central trough and so enable air and flame flow to transcend the firebed. The flames are thus drawn over pre-heated aeration vents 52, creating clean burn and super-heated air jets from vents 52 induce combustion in a highly aerated manner, forcing more complete combustion of airborne resinous particles and, in the front direction blowing super heated air towards the stove glass window, to maintain cleanliness.

The present invention is equally suitable for adaptation of existing open or removable firegrates (with gaps sealed in the firegrate beyond the outer edges of the firebed), or for inclusion in new stoves or fireplaces.

In use, an upward draught caused by the intense heat in the centre base core of the fire induces accelerated movement of a substantially horizontal airflow through the air funnel, resulting in an increase in the intensity of heat between the insulated radiant ash and the fuel above, perpetuating the cycle of upward draught and directed forced aeration. This results in a near complete combustion of the solid fuel and lower emissions to flue and atmosphere. In addition, the fire is more easily ignited, and an increased heat output is observed from the burnt fuel.

The present invention is based on the finding that one or more concentrations of air released substantially horizontally and diagonally over the fire bed ash into the fires main points of ignition, will oxygenate the fuel in sufficient quantity to maximize thermal heat output, while minimizing carbon emission.

A further problem of existing stoves is the difficulty of ignition of the fire, and also a cooling of the stove and flue experienced as a result of air that is drawn away from the fire and directly into the flue. By drawing primary air by means of the fire, the present invention overcomes this problem.

Thus is in contrast to a stove according to the present invention, where the air drawn by the flue is naturally preheated as it is necessarily drawn through the fire as a result of the specific construction of the firebed.

In addition, ignition of the fire is vastly improved above all other methods by the draught to its core that forces all the air movement through the flames maximising the efficiency of combustion. This increased efficiency brings the stove to a more rapid optimum burning temperature. It is recognised that combustion of specific dried fuels exaggerates the low carbon emission results, at optimum burning temperatures.

A firebed according to the present invention is suitable for use as an integral component or as a retrospective-fit in multi-fuel stoves, woodburning stoves, solid fuel cookers, solid fuel boilers, boiler stoves and cookers, barbeques, outdoor fires for patios etc, open solid fuel convector fires, open taper inset fires, open fire baskets, conversion to all existing stove fire-grates and open fire, fire-grates as well as purpose-made models. In the case of retrospective-fitting to existing stoves and cookers, the firebed does not interfere with and can continue to use the device's existing aeration controls to provide air wash and secondary or tertiary air.

Claims

CLAIMS: 1. A firebed for a solid fuel heating apparatus, the firebed comprising a firebed base and an air funnel associated with the base, wherein the air funnel comprises an aperture through the base said aperture having a peripheral edge, and an air funnel plate supported adjacent the aperture and spaced therefrom such that the air funnel, in use, produces a substantially lateral air flow across the firebed base.
2. A firebed as claimed in claim 1 wherein at least a part of the air funnel plate is adjustable for height.
3. A firebed as claimed in claim 1 or claim 2 wherein the aperture and air funnel plate are correspondingly elongate.
4. A firebed as claimed in claim 3 wherein the air funnel plate has a V-shaped cross-section to form a cradle.
5. A firebed as claimed in claim 3 or claim 4 wherein the firebed base comprises a pair of elongate plates held in a spaced configuration defining the aperture therebetween.
6. A firebed as claimed in any preceding claim further comprises an air funnel plate adaptor supportable by the air funnel plate to modify air flow through the air-funnel.
7. A firebed as claimed in claim 6 wherein the air funnel plate adaptor is substantially W-or M-shaped, and complementary in shape to the air funnel plate.
8. A firebed as claimed in claim 6 or claim 7 wherein the adaptor further comprises a series of aeration holes or slots in regions which do not overlay the air funnel plate.
9. A firebed as claimed in claim 1 or claim 2 wherein the air funnel is defined by an air funnel plate formed as a substantially flat plate and a cylindrical member between the aperture and the air funnel plate to an upper end of which cylindrical member the plate is axially mounted with a space therebetween.
10. A firebed as claimed in claim 9 wherein the substantially flat plate is coupled to the cylindrical member.
11. A firebed as claimed in claim 9 or claim 10 wherein the space between the plate and cylindrical member is between 1 and 5mm; more preferably between 1 and 3mm and most preferably about 2mm.
12. A solid fuel heating apparatus comprising a firebed as claimed in any preceding claim.
13. An apparatus as claimed in claim 12 further comprising a cooking cavity below the firebed.
14. A solid fuel heating apparatus comprising a firebed as claimed in any one of claims 1 to 11 and further comprising a combustion chamber having, at a rear or side face thereof, a cavity plate spaced from said face to define a cavity therebetween and having a lower edge spaced from the firebed to define an aperture therebetween.
15. An apparatus as claimed in any one of claims 12 to 14 further comprising a heat-exchanging apparatus within the cavity, the heat exchanging apparatus being fluidly coupable to an external space-heating apparatus.
16. A firebed substantially as herein described with reference to the drawings.
17. A heating apparatus substantially as herein described with reference to Figures 7to 15.