Fireplace provided with overheating protection devices

Abstract

The present invention relates to a fireplace (1) using a fuel, preferably a solid fuel such as pellets, and comprising a heating body (2) with a front upper face (40), the heating body (2) comprising a burner (8), a fuel tank (19) and a combustion chamber (3) delimited by outer walls (5, 34), the fireplace (1) being characterised in that it comprises a primary convection chamber (31) surrounding all or part of the outer walls (5, 34) of the combustion chamber (3) and a secondary convection chamber (32) surrounding all or part of the primary convection chamber (31), the primary convection chamber (31) and the secondary convection chamber (32) being positioned underneath at least one convection column, respectively referred to as a primary convection column (35) and secondary convection column (36), leading outside the fireplace (1).

Description

FIREPLACE EQUIPPED WITH OVERHEATING PROTECTION DEVICES Subject of the invention

[0001] The present invention relates to a fireplace provided with devices for protecting the sensitive components of the fireplace as well as its fuel against the risks of overheating. Technological background and state of the art

[0002] Individual heating systems are characterized by the fact that the heat generated by their combustion chamber is mainly returned directly, via their heating body, to the rooms in which they are placed.

[0003] In order to optimize combustion quality, the combustion zones are heated to very high temperatures (over 500°C). The heat produced during this process must then be transferred to the rooms to be heated in order to limit losses linked to the evacuation of combustion gases and thus maximize the efficiency of the fireplace. This transfer is carried out, on the one hand, by radiation from the combustion chamber and, on the other hand, by the transmission of heat between the hot walls and the ambient air, the heat distribution then being carried out by natural or forced convection of this hot air in the room.

[0004] Managing the energy flow from the combustion process is a challenge in terms of product performance, but it also has a significant impact on the ergonomics of use and safety of fireplaces. Indeed, certain elements can deteriorate or even catch fire if subjected to high temperatures. Furthermore, fireplace users may be required to handle certain components and must not experience any discomfort or risk of burns during these operations.

[0005] Furthermore, in the case of pellet fireplaces, the fuel tank is a particularly difficult element to protect against the risk of overheating. Indeed, on the one hand, the presence of fuel and the limits set by standards require that all the walls of the tank be kept at less than 65 Kelvin above ambient temperature. On the other hand, in order to allow the tank to be refilled during use, the parts handled during this operation must be kept below certain limits imposed by the standards. For steel parts, this temperature cannot exceed 35 Kelvin above ambient temperature. Finally, the devices for conveying fuel between the tank and the burner induce a significant risk of heat transmission between these two elements.This risk is particularly significant during phases of malfunction of the control and management devices of the fireplaces, such as during power outages. During these critical phases, it is therefore necessary to eliminate any risk of heat transfer and fire propagation via the conveying devices.

[0006] Then, the door of the hearths being an area generating a very significant part of the heat flow produced by the heating body and the heat generated by the combustion chamber rising naturally under the effect of natural convection, the parts of the facade located at the level of the chamber and above it are generally subjected to very high temperatures. On the other hand, being easier to lower fuel by gravity into a combustion chamber than to raise it, the majority of tanks are positioned at the rear of the combustion chambers and are equipped with a loading hatch located on the rear of the upper horizontal wall of the hearths. This induces two important constraints. On the one hand, this positioning limits the height of the hearth because the upper horizontal surface of it must remain sufficiently low to allow easy loading of the fuel.On the other hand, it prevents the fireplace from being built into a wall, as the upper horizontal surface of the fireplace must remain accessible.

[0007] We can see that there are many problems within a home linked to the management of heat flows.

[0008] From US 4,047,490 a recuperative heating system is known having coaxial ducts around the flue with an inner duct and an outer duct. There is a fresh air flow path downward from a cold air inlet along the outer duct and upward along the inner duct in direct heat exchange relationship with the outer surface of the flue, the air flow then escaping outward from the inner duct into a hot air exhaust duct to the room.

[0009] From US 4553528 there is known a fireplace apparatus comprising a plurality of chambers through which air circulates to be heated by heat from the combustion chamber, these chambers being adjacent to different parts of the combustion chamber and the chimney flue. Aims of the invention

[0010] The present invention aims at the design of a set of technical devices for protecting the sensitive components of fuel-fired fireplaces, preferably solid fuel, against the risks of overheating. Several technical devices cooperate in order to screen the radiation emitted by the hot surfaces of the combustion chamber and to prevent the hot air flows from reaching the areas comprising critical elements such as the fuel tank and the fuel loading hatch. These devices make it possible to avoid the risks of overheating during normal operation of the appliance but also during phases of malfunction of the control and piloting devices of the fireplaces such as, for example, during power cuts.

[0011] For this purpose, the hearth comprises several convection devices for evacuating the air heated in contact with the combustion chamber. More specifically, the invention relates to a fuel hearth, preferably solid such as pellets, comprising a heating body with a front upper face, the heating body comprising a burner, a combustion chamber delimited by external walls and at least one sensitive component provided with external faces which must be maintained at a temperature below 50°C, said sensitive component being located at least partly above the combustion chamber, the hearth being characterized in that it comprises a primary convection chamber surrounding all or part of said external walls of the combustion chamber and a secondary convection chamber surrounding all or part of the primary convection chamber, said primary convection chamber and said secondary convection chamber being surmounted by at least one convection column, called respectively primary and secondary, opening outside the hearth, the secondary convection chamber and / or said at least one secondary convection column being in contact with all or part of the external faces of said at least one sensitive component in order to maintain said external faces at a temperature below 50°C.

[0012] The presence of several convection chambers and convection columns allows, on the one hand, to maximize the energy efficiency of the fireplace and, on the other hand, to protect certain components which cannot be exposed to high temperatures such as the pellet tank or its loading hatch which must be handled with bare hands when the fireplace is in operation.

[0013] In combination with the various convection chambers and columns mentioned above, the hearth according to the invention comprises a fuel loading hatch positioned above the combustion chamber, said loading hatch being, in the closed position, housed in a cutout made on the upper front face of the heating body and concealed behind the upper facade facing.

[0014] Compared to traditional fireplace configurations in which the loading hatch is located on the rear part of the upper horizontal wall of the fireplace, being able to load the fireplace from the front offers several advantages: The hatch being located on the front face, the heating body can be recessed, the other faces no longer being accessible in this integration mode. The hatch is located lower than the upper horizontal wall of the fireplace, which limits the height of fuel pouring and improves user ergonomics. The loading hatch does not take up space on the upper horizontal wall of the fireplace. This increases the space available for placing certain important functional elements of the fireplace such as hot air exhaust grilles or the flue. Since hot air tends to rise vertically, being able to position the hot air exhaust grilles on the upper horizontal wall of the fireplace facilitates convection dynamics compared to fireplaces whose grilles are positioned on the front, requiring a horizontal deviation of the hot air flow. Since the convection heat is diffused by the hot air exhaust grilles at the upper horizontal wall of the fireplace, it does not contribute to increasing the amount of heat produced at the front of the heating body, as is the case for fireplaces where the air exhaust grilles are positioned at the front. This is a significant advantage in the case of fireplaces having a significant part of their heat diffused through their door and which can induce discomfort following overheating near the latter. This is all the more problematic when the process of reloading the fireplace in operation requires the user to position themselves near the front part of the fireplace.

[0015] The fireplace according to the invention may further have one or more of the following characteristics: - it comprises at least one smoke evacuation channel, said smoke evacuation channel being surrounded by the primary convection chamber; - the primary convection chamber is surmounted by two primary convection columns arranged laterally with respect to the secondary convection column; - it has an intermediate wall separating the primary convection chamber into two complementary chambers; - the intermediate wall also separates said at least one primary convection column into two complementary columns; - the fuel reserve is positioned at the rear of the secondary convection chamber; - the primary convection chamber and the secondary convection chamber are not in fluid communication and the primary convection chamber surmounted by the primary convection column and the secondary convection chamber surmounted by the secondary convection column are crossed by an ascending air flow; - said at least one secondary convection column is delimited by the upper front face of the heating body, by a facade facing of the hearth and by a U-shaped profile positioned between the upper front face of the heating body and the facade facing, said U-shaped profile being able to be fixed on the upper front face of the heating body or on the facade facing; - the loading hatch is cooled in use by the secondary convection column licking its surface; - the loading hatch is pivotally mounted along a horizontal axis located on the lower edge of said loading hatch, said loading hatch being integral with a chute fixed to an internal part of the loading hatch, said chute forming a bridge between the loading hatch and the interior of the fuel tank; - it includes an indexable stop mechanism allowing the degree of opening of the loading hatch to be adapted in order to optimize its ergonomics of use according to product configurations and user preferences; - it comprises a fuel supply device comprising a first screw and a second screw housed respectively in a first tube and a second tube connected by a junction element provided with a removable hatch giving access to a hollow volume allowing the transfer by gravity of the fuel conveyed from the fuel tank by the first screw to the second screw with said second screw ensuring the transfer between the junction element and the burner of the hearth; - the hollow volume of the junction element comprises sealing means capable of filling the hollow volume during a return of fire between the burner and the fuel tank, said sealing means being able to be introduced or extracted from the junction element via the removable hatch.

[0016] The present invention also relates to a fuel-fired hearth, preferably solid fuel such as pellets, comprising a heating body comprising a combustion chamber, a fuel reserve, a burner and a fuel supply device, said fuel supply device comprising a first screw and a second screw housed respectively in a first tube and a second tube connected by a junction element provided with a removable hatch giving access to a hollow volume allowing the transfer by gravity of the fuel conveyed from the fuel tank by the first screw to the second screw with said second screw which ensures the transfer between the junction element and the burner of the hearth, the hollow volume of the junction element comprising closure means which can be introduced or extracted from the junction element via the removable hatch,said sealing means being capable of expanding during a return of fire between the burner and the tank in order to obstruct the passage of fuel between the first screw and the second screw, said sealing means allowing the passage of fuel in the absence of return of fire between the burner and the tank.,

[0017] According to a variant, the sealing means have a given geometric shape with an inner wall delimiting a space for the passage of fuel in the absence of return of fire, said inner wall being made of a material expanding under the effect of heat via a thermochemical process.

[0018] The implementation of this device, which can operate under the simple effect of an abnormal increase in temperature and without the need for electricity, in order to cut off the heat flow which could be generated between the burner and the tank, helps to limit as much as possible the risks of overheating at the level of the components of the tank and its contents. Brief description of the figures

[0019] Figure 1 represents a three-dimensional view of the hearth according to the invention.

[0020] Figure 2 shows this same fireplace with the facing facade in the open position. In Figure 3, the fuel loading hatch is also in the open position for this same fireplace.

[0021] Figure 4 shows the loading hatch opening mechanism for three separate opening positions.

[0022] Figure 5 shows a perspective view of the hearth with the heat flows within the chambers and convection columns shown schematically.

[0023] Figure 6 represents a vertical sectional view of the hearth according to the invention.

[0024] Figures 7 to 10 show the hearth according to the invention with different horizontal sectional views in the upper part of the hearth above the combustion chamber.

[0025] Figure 11 shows a horizontal sectional view of the combustion chamber with the technical elements connected to the rear of said combustion chamber.

[0026] Figure 12 shows a vertical sectional view of the burner fuel supply device and the bottom of the tank.

[0027] Figure 13 represents a three-dimensional view of this same device and Figure 14 a partially exploded view of this device.

[0028] Figure 15 shows another three-dimensional view of this device with a vertical section at the feed screws.

[0029] Figure 16 shows another three-dimensional view of this device with the removable hatch in exploded view.

[0030] Figure 17 shows two three-dimensional views of the closure means intended to be arranged between the two feed screws with on the left the closure means in the open position and on the right the closure means in the closed position.

[0031] Legend (1) home (2) heating body (3) combustion chamber (4) door (5) side wall of the combustion chamber (6) combustion chamber lining elements (7) hearth sole (8) burner (9) air inlet (10) ash removal device (11) flue (12) first screw (13) first tube (14) second screw (15) second tube (16) tube junction element (17) hollow volume (18) removable hatch (19) fuel tank a. external face (20) means of closure, also called vertical ring (21) inner wall of the ring (22) means of closure in open position (23) means of closure in closed position (24) loading hatch a. external face (25) opening, also called cutout, made on the face of the tank (26) horizontal axis of the hatch (27) chute (28) indexable stop mechanism (29) tank junction device (30) reservoir mouth (31) primary convection chamber a. first part b. second part (32) secondary convection chamber (33) smoke evacuation channels (34) upper wall of the combustion chamber (35) primary convection columns a. first part b. second part (36) secondary convection column (37) intermediate convection wall of the primary convection chamber (38) upper facade cladding (39) U-shaped profile (40) upper front face of the heating body (41) upper wall of the hearth, also called the top of the hearth (42) hot air exhaust grille

[0032] The present invention relates to a solid fuel fireplace 1, preferably pellets, with a heating body 2 comprising a combustion chamber 3 intended to produce heat. The combustion chamber 3 is closed by a door 4 and delimited by side walls 5 visible in figures 6 and 11 with possibly lining elements 6 covering the side walls 5. These side walls 5 are surmounted by upper walls 34 which also frame the combustion chamber 3 with possibly the intermediate lining elements 6. The heating body 2 is delimited in its upper part above the combustion chamber 3 by a front upper face 40 covered with a facade facing 38 (figs. 1 and 2). The fireplace comprises one or more sensitive components whose external walls must be maintained at a temperature below 50°C. Typically, these components are the fuel tank and the loading hatch.Thus, the hearth is provided with a fuel tank 19, in particular for pellets, and a loading hatch 24 (figs. 3 and 7). According to the invention, the loading hatch 24 is preferably located on the upper front face 40 of the heating body, just behind the facade facing 38 and above the door 4 of the combustion chamber 3 (fig. 2).

[0033] The fuel tank 19 arranged after the loading hatch 24 supplies the burner 8 via two supply tubes 13 and 15 with a respective screw 12 and 14, visible in figures 12 to 14. The tube 13 in the upper position is connected to the fuel tank 19 and the tube 15 in the lower position is connected to the rear of the combustion chamber 3 on a side wall 5 (fig. 11). In order to optimize the possibilities of standardization, these tubes 13 and 15 comprise connecting elements 16 and 29 allowing respectively a relative rotation between the two tubes 13, 15 and a relative rotation between the tube 13 in the upper position and the tank 19 (figs. 13 and 14).

[0034] According to the invention, the fireplace comprises a set of devices which make it possible to limit the overheating of sensitive components. Advantageously, it can also comprise means which make it possible to prevent a return fire between the burner and the pellet tank.

[0035] Thus, the heating body 2 comprises several convection devices 31, 32, 35, 36 formed of convection chambers and convection columns allowing the hot air to be evacuated to the outside of the hearth. The hearth comprises a succession of convection chambers with a first chamber 31, called primary, and a second convection chamber 32, called secondary, illustrated schematically in Figures 5 to 10.

[0036] The primary chamber 31 is located behind the side walls 5 and the upper walls 34 of the combustion chamber. It surrounds all or part of these walls. Preferably, it also surrounds the smoke evacuation channels 33 of the combustion chamber 3 (fig. 7). This chamber 31 is surmounted by at least one primary convection column 35. Preferably, it is surmounted by two primary convection columns 35 positioned laterally in the heating body and opening at the top 41 of the hearth at the air evacuation grille 42. Preferably, in order to limit the heat transfer between the internal and external walls of the chamber 31 and the convection columns 35, an intermediate wall 37 can be positioned within the primary chamber in order to separate it into two volumes. Preferably, each primary convection column 35 is also separated by the intermediate wall 37 into two volumes 35a, 35b.Thus, the primary chamber 31 and the evacuation columns are separated into two parts 31a, 31b and respectively 35a, 35b with advantageously the smoke evacuation channels 33 arranged within the interior parts 31a, 35a (figs. 8 and 9).

[0037] A second convection chamber 32, called secondary, is arranged after the primary chamber 31. It surrounds all or part of the primary chamber, preferably the entire primary chamber. The secondary chamber 32 is surmounted by a secondary convection column 36 positioned at the front between the lateral convection columns 35 of the primary chamber 31 (fig. 5). This secondary convection column 36 is delimited by the upper front face 40 of the heating body, the front facing 38 of the hearth and by a U-shaped profile 39 positioned between these two elements, visible in more detail in figures 2 and 6. This U-shaped profile 39 can be fixed on the upper front face 40 of the heating body or on the front facing 38 of the hearth. The lower part of the profile 39 prevents the hot air generated at the level of the door 4 does not mix with the tempered air circulating in the volume of the secondary convection column 36 (fig. 6). According to the invention, the secondary convection chamber and / or the secondary convection column is in contact with the external face of the sensitive components. More precisely, as shown in figure 6, the secondary convection chamber 32 is in contact with the external face 19a of the fuel tank 19 and the secondary convection column 36 is in contact with the external face 24a of the loading hatch 24. Thus, this device with double convection chambers and convection columns makes it possible to maintain the walls 19a of the tank 19 as well as the loading hatch 24 of the hearth at temperatures below 50°C despite certain temperatures exceeding 500°C inside the combustion chamber 3.

[0038] In order to facilitate the loading of pellets into the tank 19, the hearth is provided with the loading hatch 24 applied, in the closed position, to a cutout 25 made on a vertical face giving access to the tank 19, and more precisely on the upper front face 40 of the heating body (fig. 3). The hatch is cooled by the cold secondary convection column which licks its surface and protected from the hot primary convection columns which are guided on the sides of the hearth. When it opens, this hatch 24 pivots about a horizontal axis 26 located on the lower edge thereof and carries with it a chute 27 fixed on the upper internal part of the hatch and sliding, by appropriate means 28, inside the cutout 25 made on the vertical face giving access to the tank 19 (fig. 3). Said chute 27 thus forms a bridge between the upper end of the hatch and the interior of the tank (figs. 2 to 4).According to a preferred embodiment, the device allowing the chute 27 to slide is provided with an indexable stop mechanism 28 allowing the degree of opening of the hatch to be adapted in order to optimize its ergonomics of use according to the product configurations and user preferences (fig.4).

[0039] The fuel supply system also constitutes a critical element of the fireplace in terms of safety. Indeed, any risk of fire returning between the burner 8 and the tank 19 must be avoided. For this, the junction element 16 of the tubes 13, 15 is provided with a removable hatch 18, giving access to a hollow volume 17 allowing the transfer by gravity of the fuel conveyed by the first screw 12 from the tank 19, towards the second screw 14, ensuring the transfer between the junction element 16 and the burner of the hearth 8 (figs. 12 and 14). This transfer creates a discontinuity between the bed of pellets located in the bottom of the first tube 13 and that located in the bottom of the second tube 15, preventing the spread of the fire from one bed to the next between these two beds (fig. 12).

[0040] On the other hand, the hollow volume 17 of the junction element 16 comprises arrangements allowing the positioning of closure means 20 visible in figures 15 to 17. These can be introduced or extracted from the junction element 16 via the removable hatch 18. During normal operation of the hearth, the closure means 20 are maintained in their open position referenced with the reference 22 on the left of figure 17 and do not affect the transfer by gravity of the fuel. In the event of a return of fire from the burner 8 to the second tube 15, the increase in temperature at the level of the closure means will induce a closure of these visible on the right of figure 17 with the reference 23, thus preventing the transfer of the fuel and the heat flow to the first tube 13 and the tank 19. Typically, the closure means are in the form of a vertical ring with an inner wall 21 capable of expanding under the effect of heat.According to a preferred embodiment, the closure means delimit in the open position a recess with the walls 21 made of a material expanding under the effect of heat following a thermochemical process and leading to the closure of the means 20 in the event of a return of fire. Typically, the inner wall 21 is made of a strip of intumescent material based on graphite. It could also be a mechanical device such as a diaphragm or a guillotine which would engage under the effect of heat.

Claims

CLAIMS 1. A hearth (1) for fuel, preferably solid fuel such as pellets, comprising a heating body (2) with a front upper face (40), the heating body (2) comprising a burner (8), a combustion chamber (3) delimited by external walls (5, 34) and at least one sensitive component (19, 24) provided with external faces (19a, 24a) which must be maintained at a temperature below 50°C, said sensitive component (19, 24) being located at least partly above the combustion chamber (3), the hearth (1) being characterized in that it comprises a primary convection chamber (31) surrounding all or part of said external walls (5, 34) of the combustion chamber (3) and a secondary convection chamber (32) surrounding all or part of the primary convection chamber (31), said primary convection chamber (31) and said secondary convection chamber (32) being surmounted of at least one convection column, called respectively primary (35) and secondary (36),opening outside the hearth (1), the secondary convection chamber (32) and / or said at least one secondary convection column (36) being in contact with all or part of the external faces (19a, 24a) of said at least one sensitive component (19, 24) in order to maintain said external faces (19a, 24a) at a temperature below 50°C., 2. Hearth (1) according to claim 1, characterized in that said at least one sensitive component is a fuel tank (19) and / or a fuel loading hatch (24).

3. Hearth (1) according to claim 1 or 2, characterized in that the hearth (1) comprises at least one smoke evacuation channel (33), said smoke evacuation channel (33) being surrounded by the primary convection chamber (31).

4. Hearth (1) according to one of the preceding claims, characterized in that the primary convection chamber (31) is surmounted by two primary convection columns (35) arranged laterally with respect to the secondary convection column (36).

5. Hearth (1) according to one of the preceding claims, characterized in that it comprises an intermediate wall (37) separating the primary convection chamber (31) into two complementary chambers (31a, 31b).

6. Hearth (1) according to the preceding claim, characterized in that the intermediate wall (37) also separates said at least one primary convection column (35) into two complementary columns (35a, 35b).

7. Hearth (1) according to one of the preceding claims, characterized in that the primary convection chamber (31) and the secondary convection chamber (32) are not in fluid communication and in that the primary convection chamber (31) surmounted by the primary convection column (35) and the secondary convection chamber (32) surmounted by the secondary convection column (36) are crossed by an ascending air flow.

8. Fireplace (1) according to one of claims 2 to 7, characterized in that the fuel tank (19) is positioned at the rear of the secondary convection chamber (32).

9. Hearth (1) according to one of the preceding claims, characterized in that said at least one secondary convection column (36) is delimited by the upper front face (40) of the heating body, by a front facing (38) of the hearth (1) and by a U-shaped profile (39) positioned between the upper front face (40) of the heating body and the front facing (38), said U-shaped profile (39) being able to be fixed on the upper front face (40) of the heating body or on the front facing (38).

10. Fireplace (1) according to one of claims 2 to 9, characterized in that the fuel loading hatch (24) is positioned above the combustion chamber (3) with said loading hatch (24) in the closed position being housed in a cutout (25) made on the upper front face (40) of the heating body.

11. Hearth (1) according to the preceding claim, characterized in that the loading hatch (24) is cooled in use by the secondary convection column (36) licking its surface.

12. Fireplace (1) according to one of claims 2 to 11, characterized in that the loading hatch (24) is pivotally mounted along a horizontal axis (26) located on the lower edge of said loading hatch (24), said loading hatch (24) being integral with a chute (27) fixed to an internal part of the loading hatch (24), said chute (27) forming a bridge between the loading hatch (24) and the interior of the fuel tank (19).

13. Hearth (1) according to one of claims 2 to 12, characterized in that it comprises an indexable stop mechanism (28) making it possible to adapt the degree of opening of the loading hatch (24) in order to optimize the ergonomics of use according to the product configurations and user preferences.

14. Hearth (1) according to one of claims 2 to 13, characterized in that it comprises a fuel supply device comprising a first screw (12) and a second screw (14) housed respectively in a first tube (13) and a second tube (15) connected by a junction element (16) provided with a removable hatch (18) giving access to a hollow volume (17) allowing the transfer by gravity of the fuel conveyed from the fuel tank (19) by the first screw (12) to the second screw (14) with said second screw which ensures the transfer between the junction element (16) and the burner (8) of the hearth (1).

15. Hearth (1) according to the preceding claim, characterized in that the hollow volume (17) of the junction element (16) comprises closure means (20) capable of filling the hollow volume (17) during a return of fire between the burner (8) and the fuel tank (19), said closure means (20) being able to be introduced or extracted from the junction element (16) via the removable hatch (18).

16. A fireplace (1) for fuel, preferably solid fuel such as pellets, comprising a heating body (2) comprising a combustion chamber (3), a fuel tank (19), a burner (8) and a fuel supply device, said fuel supply device comprising a first screw (12) and a second screw (14) housed respectively in a first tube (13) and a second tube (15) connected by a connecting element (16) provided with a removable hatch (18) giving access to a hollow volume (17) allowing the transfer by gravity of the fuel conveyed from the fuel tank (19) by the first screw (12) to the second screw (14) with said second screw ensuring the transfer between the connecting element (16) and the burner (8) of the fireplace (1), the hollow volume (17) of the connecting element (16) comprising closure means (20) which can be introduced or extracted from the connecting element (16) via the removable hatch (18), said closure means (20) being capable of expanding during a return of fire between the burner (8) and the tank (19) to obstruct the passage of fuel between the first screw (12) and the second screw (14), said closure means (20) allowing the passage of fuel in the absence of return of fire between the burner (8) and the tank (19).

17. Hearth (1) according to the preceding claim, characterized in that the closure means (20) have a given geometric shape with an inner wall (21) delimiting a space for the passage of fuel in the absence of return of fire, said inner wall (21) being made of a material expanding under the effect of heat via a thermochemical process.

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