Abstract:
A closed fireplace ( 1 ) having a display glass, a hearth provided with a grating ( 29 ), an ignition device, an ash receptacle ( 31 ), a combustion replacement air supply and a discharge line for fumes. The fireplace also having a flat body chamber ( 2 ) in the form of a closed box to be attached to a wall or partially or fully integrated into the wall or into a canopy thereof, the internal volume of the flat body being divided into two flat adjacent chambers for combustion ( 4 ) and storage ( 5 ), the storage chamber forming a stock of wood ( 6 ). The chambers are separated by a dividing and thermally insulating wall ( 8 ) for supplying the pre-heated secondary air for the combustion, the bottom of the storage compartment having an inclined ramp ending in the lower part of a hearth ( 34 ). The invention is especially suitable for manufactures of fireplaces especially designed for wood fires.

Description:
[0001]    This application is a national stage completion of PCT/EPFR2005/000839 filed Apr. 6, 2005 which claims priority from French Application Serial No. 0403595 filed Apr. 6, 2004. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention concerns a compact wall fireplace using solid fuel, especially wood, presenting a closed flat hearth which may be extra flat, specifically designed for an apartment or a private home. 
         [0003]    More specifically, the invention relates to a wall fireplace with a closed hearth with the hearth being automatically stoked with wood from a storage supply and with an integrated remote ignition system. 
       BACKGROUND OF THE INVENTION 
       [0004]    A wood burning fireplace in a home is an amenity appreciated by everyone. 
         [0005]    Not only does it provide the spectacle of flames, it offers warmth, hospitality and comfort. For some people, it has considerable sentimental appeal. Everyone appreciates the attractive display of a fire which, in addition to being soothing, provides pleasure and heat. Moreover, its presence offers a convivial atmosphere and gathering place for both family members and guests. 
         [0006]    A conventional fireplace, however, requires space for installation and it is not always possible to find this amount of space in a home or to easily free up enough space for a fireplace installation, particularly in the case of an apartment or a small private home. 
         [0007]    For these reasons, several solutions have been proposed to offer the attractiveness of a fire to those who are unable to install a fireplace at home. 
         [0008]    For example, there are recorded videocassette fires for viewing on television or artificial fireplaces occupying a small amount of space which simulate the visual display of a fireplace fire. 
         [0009]    Such a simulation device may comprise artificial plastic logs with electrical illumination to create a glow, a dynamic light system for radiating flames, lighted strips illuminated by red and orange lights and agitated by an air current to simulate the twinkling and movement of flames, and so forth. 
         [0010]    Technical advances have resulted in devices that improve the realistic effect even more. Such devices, however, have proven to be very frustrating, since they are based on an illusion and provide neither the charm nor the warmth of a real hearth fire. 
         [0011]    There is a real need for an actual fireplace that could be installed in an apartment or a private home and occupy only a small amount of floor space or even a wall fireplace that would not project onto the floor at all. 
         [0012]    Advantageously, such a fireplace, besides being smaller, should offer an optimal or even panoramic view of the hearth, making it possible to fully enjoy the spectacle of the flames. 
         [0013]    Moreover, such a fireplace should satisfy various safety regulations, be practical to use and ensure optimal cleanliness. 
         [0014]    Preferably, it should be quick, easy, clean and danger-free so that any user could quickly and easily enjoy a fireplace fire without the least inconvenience. 
         [0015]    The object of the invention is to provide a compact, closed fireplace, wall fireplace using solid fuel which is extremely simple to use and can be installed in an apartment or a private home. 
       SUMMARY OF THE INVENTION 
       [0016]    The invention also proposes a wall fireplace whose principal operations function simply and automatically: lighting, fuel supply, cleaning, etc. 
         [0017]    To obtain the practical operational features desired, therefore, this fireplace consists of an integrated solid fuel reserve, specifically for wood, to automatically supply the fireplace. Loading the fuel will also be accomplished quickly, easily, cleanly and safely. 
         [0018]    Since the period of use for such a fireplace is generally limited, the solid fuel storage capacity may be calculated to supply fuel for approximately two to three hour duration on average corresponding to the length of an evening. 
         [0019]    To resolve this technical problem, the fireplace of the invention comprises a display glass, a hearth equipped with a grate, preferably a remote control ignition device, an automatic wood supply, an ash receptacle, a dual combustion air supply and combustion smoke/gas outlet device, with everything designed so the fireplace can be compact, that is, as shallow as possible. 
         [0020]    To achieve this, each of the elements constituting the invention is designed to contribute to production of an attractive product enhanced by multiple features. 
         [0021]    The display window is preferably as large as possible or even panoramic relative to the hearth. It is located in the immediate proximity of the hearth so it can fully set off the spectacle of the wood burning fire. Preferably, it projects only slightly from the wall within which the fireplace may be integrated, thus occupying only a small amount of space within the room. 
         [0022]    Likewise, the ash receptacle located below the hearth grate may advantageously extend into the wall. Therefore, it is readily accessible for emptying. 
         [0023]    To improve functioning and automatic operation, the hearth supporting grate or the ash grate is made to move in alternate displacement by a specific control, but also by the movement of the front air inlet register which controls it. 
         [0024]    The ignition device preferably comprises at least one reinforced resistor in order to safely ignite the wood log supported by the hearth grate by remote control. 
         [0025]    The wood storage area may be formed of a vertical compartment that is slightly deeper than the diameter of the average log. It is situated at the back of the fireplace and it abuts the fireplace, from which it is separated by a thermal insulating wall that is preferably hollow and which also serves to admit secondary combustion air into the hearth. 
         [0026]    This fuel storage area is filled by stacking logs, wood rounds or pieces of wood of average diameter adapted to the size of the storage compartment. Advantageously, an inclined plane in the lower portion of this storage area may allow the logs or wood rounds to roll or slide to the level of the hearth so that when a first log or round has been completely consumed, a new log or wood round arrives to take it place. This storage area is preferably accessible for reloading from the fireplace side or from the back; in the latter case, opening onto the opposite surface of the wall in which it is installed or in some other way. 
         [0027]    In one version of the automatic supply operation, the storage unit may comprise a drawer to be loaded with logs or wood rounds. It may be possible to fill this loading drawer with a cassette serving as a container for previously stacked logs or rounds, thereby allowing wood to be loaded in advance to save extra time. 
         [0028]    New air for combustion arrives through two channels: a principal channel for primary combustion air arriving through the bottom of the front surface through a front air inlet register and a supplemental channel bringing secondary combustion and post-combustion air. This secondary air channel originates in the lower portion at the rear of the fireplace, arrives above the fireplace through the separating wall, exiting on the one hand, at the lower extremity of this separating wall and on the other hand, along a post-combustion ramp located higher up. This secondary air is, therefore, preheated and this arrangement also creates of a thin stream of air in the separating wall that forms the thermal insulation, thereby preventing the stored wood and the escaping hot gases from catching fire. 
         [0029]    For this purpose, the separating wall preferably takes the form of two generally parallel, vertical plates with the space separating them defining a flat thermal insulation space. This wall for supplying secondary combustion air creates a supplemental flow of air which, along with the principal air, ensures complete combustion and post-combustion of the log or wood round in place on the fireplace grate and of the volatile materials that often remain uncombusted. 
         [0030]    The air outlet at the opening of the separating wall may be completely free or it may consist of a series of holes judiciously disposed for optimal distribution of combustive air. 
         [0031]    Finally, the smoke evacuation outlet is located in the upper part of the fireplace above the hearth. It preferably takes the form of a smoke box with a vertical outlet or a horizontally angled return. It preferably consists of a chimney type evacuation conduit or of what is called a microvent. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    The invention will now be described, by way of example, with reference to the accompanying drawings in which: 
           [0033]      FIG. 1  is a schematic perspective of the preferred mode of embodiment of the fireplace, according to the invention, during operation with the obscuring lateral surface on its first plane removed; 
           [0034]      FIGS. 2 and 3  are simplified perspective views with the door open and closed, respectively, of a first variation in the execution of the fireplace of the invention; 
           [0035]      FIGS. 4 and 5  are perspective views of a second variation in the execution of the fireplace of the invention with the door open and closed, respectively; 
           [0036]      FIG. 6  is a median longitudinal cross-section of the fireplace corresponding to an industrial embodiment; 
           [0037]      FIG. 7  is a detailed perspective view of the front of the fireplace according to the invention; 
           [0038]      FIG. 8  is a detailed perspective view of the rear of the fireplace according to the invention; 
           [0039]      FIG. 9  is an exploded perspective view of the fireplace according to the invention corresponding to  FIGS. 7 and 8 ; 
           [0040]      FIGS. 10 through 13  are schematic cross-sections of examples of installation of the fireplace of the invention shown integrated within a wall and attached to a wall, respectively; 
           [0041]      FIG. 14  is a simplified perspective showing the front principal combustion air intake register; 
           [0042]      FIG. 15  is a simplified perspective showing the mechanical connection between the grate and the front principal air intake register, and 
           [0043]      FIGS. 16 and 17  are schematic perspective views showing two types of wood loading devices using a lateral drawer cassette and a tilting cassette, respectively. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]    A fireplace, according to the present invention, will now be described in detail with reference to the various drawings. Equivalent elements shown in these drawings will bear the same reference numerals. 
         [0045]    In this description the term “front fireplace surface” will denote the surface comprising the display glass and the term “rear surface” will denote the surface that is hidden because it is applied to the wall or located inside the wall. 
         [0046]    It is apparent from the drawings that the general shape of fireplace  1  is that of a flat parallelepiped box, which may be extra flat or of a hearth thin, inside, flat box  2  forming a closed hearth having on its front surface an opening closed by a viewing and display window  3 . 
         [0047]    This display window  3  is maintained in the closed position for closing the front of the hearth, but it is movable or removable, for example, by tilting it for access inside the hearth and for cleaning. For this reason, it is preferably supported by a frame that opens, for example, by tilting it forward to ensure access to the hearth thin, inside, flat box  2 . 
         [0048]    The hearth thin, inside, flat box  2  encloses two adjacent chambers: a combustion chamber  4  forming the hearth itself and located in the front and a fuel storage chamber or compartment  5  located in the back and designed to enclose a store of solid fuel (fuel reserve)  6 , here, for example, natural wood in logs or rounds  7  or artificial compressed logs. 
         [0049]    The two compartment chambers  4  and  5  are separated along a large portion of their height by a separating wall  8  in the form of a partition. The role of this separating wall  8  is to provide not only mechanical separation, but also thermal insulation, preventing transmission of heat to the fuel reserve (solid fuel)  6  and preventing the temperature in the storage chamber compartment  5  from becoming excessive. This separating wall  8  may perform a supplemental function as will be seen below. 
         [0050]    The separating wall  8  preferably takes the form of two plates, a front and a rear plate  9  and  10 , respectively, generally parallel and vertical, defining a flat, thin interior space  11  between the plates that may either remain empty or be filled with thermally insulating material. 
         [0051]    In a preferred embodiment, the interior space  11  is empty and thus filled with air forming an air blanket  12  that is either immobile or preferably, flows downward. This arrangement provides a supplementary supply of new air from the outside for combustion which heats up when it contacts the plates, specifically front plate  9  of the separating wall  8 . This air will hereafter be termed secondary air. 
         [0052]    The principal air for combustion originates from an air inlet on the lower portion of the front surface of the box  2  as will be seen below. 
         [0053]    According to an interesting embodiment, the separating wall  8  terminates toward the base near the hearth by its lower transverse edge  13  which preferably opens at a right angle to the hearth, either directly or through an angled or inclined extension or some other configuration, thereby forming an actual air injection ramp at the rear hearth inlet. 
         [0054]    An intermediate air outlet ramp can also be provided in the upper portion of wall  8  for delivering new heated air into the space inside the combustion chamber  4  where post-combustion can take place. 
         [0055]    This ramp may be a simple air outlet in the form of a slot or other geometric shape. 
         [0056]    It is also possible to have several outlets for new secondary combustion air at different levels. 
         [0057]    Thus, the air being displaced inside the separating wall  8  may then supply the combustion chamber  4  with new combustion air above the log that is in the process of being consumed. This air is drawn to the outside and is preferably injected, for example mechanically, by a forced air flow arriving at the combustion chamber or at the combustion chamber  4 . 
         [0058]    When it travels through the separating wall  8 , it becomes heated through the front plate  9  of the wall by contact with the flames and heat from the hearth, thus transporting a large number of calories as it descends. The blanket  12  of new air thus constitutes a thermal insulation shield for the storage compartment chamber  5  located behind the hearth where the supply fuel (fuel reserve)  6  of wood is located, preventing the wood from bursting into flames spontaneously due to excessive temperature caused by direct transmission of heat from the hearth. 
         [0059]    The outlet for secondary combustion air supplying combustion chamber  4  of the hearth at the outlet of the separating wall  8  is located at least at the level of its lower transverse edge  13 . It may be completely free and open, as shown in the different drawings. It may, however, be designed to orient the flow of exiting air, for example, using a nozzle or preferably a perforated strip with a series of holes judiciously arranged to provide optimal distribution of the combustive air. 
         [0060]    The new air travels to the separating wall  8  through a lower secondary air inlet  14  that is preferably adjustable and passes through the inside of a rear wall  15  of the storage compartment  5 , then into its upper wall  16 , then descends through the separating wall  8 . 
         [0061]    The air inlet  14 , in one variation, may be thermostatically controlled, that is, adjustable according to several parameters such as room temperature or the temperature near the fireplace, in order to regulate the intensity of the fire. 
         [0062]    In order for post-combustion to occur, that is, combustion of the materials and volatile gases that did not burn in the fireplace, a post-combustion ramp  17  is provided slightly above the hearth. As shown, it may consist of a series of calibrated perforations in a linear arrangement, generally parallel to the lower edge of the separating wall  8 . The preheated new air leaving through these orifices carries the necessary oxygen at the correct temperature to allow this uncombusted material to ignite and combust. The benefit of this is that additional calories are contributed, thus improving the global calorie output. This also eliminates any ecological concerns relative to the discharge of uncombusted materials and gases into the atmosphere. 
         [0063]    Primary combustion air originates in the lower portion of the front surface of the hearth thin, inside, flat box  2  where there is an adjustable primary air inlet  18  ( FIG. 14 ). This primary air inlet  18  may be formed of a series of orifices such as an orifice  19  resulting from perforations in a linear arrangement, hidden to a greater or lesser extent by a translation piece  20  with the same pattern of perforations  21  and which can be displaced in front of the first set of perforations in order to regulate the flow of air and thus the speed of combustion. This translation piece is attached so as to be linearly displaceable, for example, through the cooperation of two rectangular lights  22  and  23  with corresponding immobilizing pins  24  and  25 . The translation piece is actuated by a manipulating lever  26 . The unit of this primary combustion air inlet  18  in the front position comprises a front air inlet register  27 . It is protected by a covering plate  28 . 
         [0064]    Here also, the principal combustion air inlet can be thermostatically controlled, that is, regulating it, i.e., the draft, depends on several parameters, some of which are described above for modifying and regulating the intensity of the fire. 
         [0065]    The hearth itself is formed of a supporting grate or cinder ash grate  29  attached above a mechanical unit  30  containing a receptacle for the ashes or an ash receptacle  31 . The ash grate is surmounted by andirons such as an andiron  32  in order to maintain the logs at a certain distance from the glass surface. 
         [0066]    For both esthetic and technical reasons, the ash receptacle  31  is preferably flat, forming a drawer, and easily accessible from one of the lateral surfaces, for example. 
         [0067]    The hearth&#39;s cinder ash grate  29  constitutes a terminal portion of zone  33  for automatically supplying fuel, preferably wood in this case, from the storage compartment  5 . This supply zone  33  principally consists of an inclined ramp  34  forming the base of the storage compartment  5  where the logs or rounds of wood  7  are stacked. 
         [0068]    This inclined ramp  34  allows each wood log or round  7  contained in the storage compartment  5  to advance by gravitational force and slide or roll into the combustion chamber  4 , arriving at the ash grate  29  to successively replace the log  7 , which is being consumed. 
         [0069]    Logs or rounds  7  arrive in contact with one another, but it is possible for the stack of logs or rounds  7  to require that an intercalary layer of combustible elements be interposed between them and/or for a lateral inlet valve to be provided in the hearth, or some other equivalent means, allowing them to be either completely or progressively admitted inside, without departing from the scope of the invention. 
         [0070]    Obviously, wooden logs or rounds  7  can be used, but also any other type of wood, for example, compressed wood, composites formed of wood byproducts or similar solid combustible materials can also be used. 
         [0071]    For ease of use, the movement of the ash grate  29 , which has its own manipulating handle  35 , is subject to the movement of the translation piece  20  on the front air inlet register  27 . 
         [0072]    This connection may be made simply, as shown in  FIG. 15 , using two transverse elements  36  and  37 , such as pins or other connecting elements, the extremities of which each penetrate a corresponding transverse opening on the ash grate  29 . Thus, when the translation piece  20  on the front air inlet register  27  is moved, the ashes are cleared out automatically. 
         [0073]    For even greater convenience, the fireplace is equipped with an automatic ignition device, for example, a remote control device. 
         [0074]    As can be seen in  FIG. 15 , the device more specifically consists of a plated electrical resistor  38  forming a loop that branches toward the upper portion of the ash grate  29  in order to make direct contact with log  7  in place on the grate. A remote control, for example, in the form of a switch I located on or near the front surface of the fireplace, controls the supply of electricity to the plated lighting resistor through an adjustable time switch. The electrical resistor  38  then becomes incandescent, allowing it to directly light the log  7  located on the ash grate  29 , easily lighting the fireplace without the necessity of opening the hearth access door or using matches. This eliminates numerous risks of accident and messiness. 
         [0075]    It is important to note that any dirt that might come from the wood storage compartment  5  also falls by gravity along inclined wood supply ramp  34  and lands in the ash receptacle  31 . This keeps the entire fireplace unit clean. 
         [0076]    The box is closed along the side by two lateral doors  39  and  40  completely blocking its lateral surfaces. The doors can be maneuvered to open each time with a handle, for example, a detachable handle such as a handle  41  that pivots on a front axle. 
         [0077]    As seen in  FIGS. 8 and 9 , at least one lateral surface of the box has an opening, such as opening  42 , for lateral access in order to load the solid fuel storage compartment  5 . Since this opening releases a certain amount of heat coming from the hearth, it has been necessary to protect the space opposite the door with a lined heat-insulated area  43  to prevent transmission of heat to the door itself. This is also true for an area  44  opposite the outlet of the ash receptacle  31 , which is also plated and heat-insulated. 
         [0078]    The hearth  4  is closed in the front by removable display window  3  made of specialized glass for viewing the fire. The inside front surface is closed at the top by a fire-proof front plate  45 . 
         [0079]    The portion of the combustion chamber  4  situated above fireplace grate  29  located between the thermal insulation separating wall  8  and the display window  3  on the box constitutes the area where the fire will start. This portion of combustion chamber  4  extends upward into a buffer space called a smoke box  46 , or its equivalent, opening into a nozzle  47  on a smoke and combustion gas evacuation conduit that may be straight  48  or angled  49 . 
         [0080]    According to a preferred embodiment, the space in the smoke box  46 , which occupies the top portion of the combustion chamber  4 , may further comprise one or more deflecting plates  50  to deflect the smoke and combustion gases towards the inlet of evacuation conduit  48  or  49  and joining the nozzle  47  which serves as a connecting piece. This nozzle  47  may also be disposed to serve as a rear outlet across plate  51  through a microvent-type co-axial conduit  52 . The top of the box is covered by a decorative grill  53 . The outlet may also be vertical. In that case, the nozzle  47  points toward the top and traverses grill  53  to connect with the straight vertical evacuation conduit  48  or the angled conduit  49 . The conduit may or may not be visible. If it is visible, it has a closed concealing shield  54  that also serves as a cover. The cover opens at the top into a mouth  55 , allowing the hot air containing the recovered calories emitted through evacuation conduit  48  to flow into the top of the room. 
         [0081]    The front surface of the box  2  is closed along the entire height by principal pivoting protective door  56  for decoration and display. The principal door  56  is pivotably connected on a right or left lateral axle. It comprises a means to immobilize it in a closed position. 
         [0082]    This principal door  56  is double. It consists of a principal glass panel  57  which is opaque along part of the surface, leaving a rectangular central display window  58  opposite the display glass  3 . As shown in  FIGS. 2 through 5 , the general shape of the principal glass panel  57  is rectangular or oval. Naturally, other decorative shapes could be used. 
         [0083]    The principal glass panel  57  extends for a certain distance and on its rear surface; there is a secondary transparent panel  59  made of glass or a similar heat-resistant material. This panel may be held in place by a frame and when the door is closed, it contacts the display glass  3  on the box  2 . The principal glass door  56  may, therefore, be considered to be a double-glass door. This succession of glass layers near the flames not only provides a direct view of the flames, but also reflections and supplemental images of the flames, adding to the magic, charm and spectacle of the fire. 
         [0084]    The extremely flat design of the unit formed by the box  2  and the hearth  1  enable it to be either mounted on, or embedded or integrated within, numerous supports without the need for much technical preparation. 
         [0085]    Because of this particularly advantageous feature, flat or extra-flat hearth  1  can be totally or partially embedded within a wall  60  or project only slightly, with its front surface being either flush with the wall or with a wall projection as shown in  FIGS. 10 and 11 . 
         [0086]    However, the usual way of attaching a hearth is to affix it flat against the wall  60 , interposing an insulating decorative plate  61  against the wall  60  at the height of an average person, as shown in  FIGS. 12 and 13 . 
         [0087]    As previously indicated, among the technical possibilities for placement, the choices are either a direct outlet through the wall, for example, through microventing coaxial conduit  52  as with gas wall heaters, or an outlet through the vertical evacuation conduit  48  with the protective cover  54  and the mouth  55  for ejection of the recovered hot air. 
         [0088]    It is important to note that the fireplace  1  according to the invention, is adaptable to any type of building or home and can be installed at different heights according to need, unlike conventional fireplaces that rest on the floor. It can also be mounted on a pedestal or suspended at virtually any height on the wall. 
         [0089]    The flat version of the fireplace is also easy to install since it does not require any pre-installation preparation. It is also very simple to use since, in order to light the fireplace, one need only load the wood and use the remote control ignition device. Maintenance is also extremely simple, since it is not necessary to clean the fireplace. All that is required is to periodically empty the ash receptacle  31  and fill the storage compartment  5  with wood. Emptying the ashes is accomplished by maneuvering the front air inlet register  27 . 
         [0090]    According to a completely manual version, the storage compartment  5  is resupplied with wood by introducing the wood rounds one at a time and stacking them one on top of the other. 
         [0091]    This convenience of this embodiment can be further improved by using a previously filled storage or reloading device  62  or one which was purchased already filled with fuel, then introducing it directly or through a loader into the storage compartment  5 . 
         [0092]    According to another embodiment, shown in  FIG. 16 , the wood storage container  6  comprises a reloader  62  and a drawer-like support  63  which, once filled with wood, is introduced laterally into the storage compartment  5  by translation, using a closing plate  64  as a ramp for it to slide along. 
         [0093]    It would also be possible for the empty supply drawer  63  to be replaced by another full drawer, previously filled, and perhaps sold empty or full in this form as a standard reloading unit, with empty drawers possibly even being consigned. 
         [0094]    As shown in  FIG. 17 , the storage compartment  5  forming the reserve  6  may receive a special loader  65  in the form of a box with a receptor compartment  66  having a lateral opening  67  tilting toward the outside to admit the reloader  62  with the logs or rounds  7  placed inside. In order for the fireplace unit to be as flat as possible, the depth of the special loader  65  is limited, generally corresponding to the diameter of the logs or rounds  7  it will contain. Its total height depends on the height of the fireplace, but it is generally sufficient to hold a large enough quantity of wood for several hours of burning. 
         [0095]    It is also possible to equip fireplaces that are embedded in the wall with a rear wood loading device on the other side of the wall. 
         [0096]    Generally, the reserve of combustible fuel  6 , specifically wood, can be reloaded whenever necessary, even while the fireplace is in use. To do this, the empty drawer must either be refilled or replaced with a full drawer. 
         [0097]    It is also possible to conceive of numerous variations of the preceding embodiments with departing from the scope of the invention. 
         [0098]    Only square or rectangular fireplaces have been described. However, other designs can be conceived and manufactured, such as triangular or circular shapes, adapting the various constituent elements of the fireplace to suit its shape. 
         [0099]    In addition, the remote control for the ignition device may also be a switch activated from a distance using a remote control device or one or more switches located in various places within the building where the fireplace is installed, or any other remote control means, such as a coded infrared emitter, for supplying electricity to the ignition device. 
         [0100]    Because of the presence of thermally insulated separating wall  8 , the amount of heat coming from the hearth and transmitted to logs or rounds  7  in fuel reserve  6  through the separating wall  8  is not sufficient to cause them to ignite. However, it does accelerate the drying process and generally improves the logs&#39; combustibility.