WO2007028257A2

WO2007028257A2 - Solid fuel furnace

Info

Publication number: WO2007028257A2
Application number: PCT/CA2006/001497
Authority: WO
Inventors: Sylvain Bilodeau
Original assignee: Sylvain Bilodeau
Priority date: 2005-09-09
Filing date: 2006-09-11
Publication date: 2007-03-15
Also published as: GB0518394D0; WO2007028257A3

Abstract

A furnace (10) for burning solid fuel using surrounding air (12). The furnace (10) includes a firebox (14) for burning the solid fuel thereinto. An air-introducing system (22) is provided for introducing the surrounding air (12) into the firebox (14). The air introducing system (22) includes a bottom system outlet (26) located within the firebox (14) substantially adjacent a firebox bottom end (16) and a plurality of top system outlets (32) located within the firebox (14) substantially adjacent a firebox top end (18), the top system outlets (32) being distributed over an air distribution surface located substantially adjacent the firebox top end (16).

Description

TITLE OF THE INVENTION

SOLID FUEL FURNACE.

FIELD OF THE INVENTION

[0001] The present invention relates to the general field of heating and is particularly concerned with a solid fuel furnace.

BACKGROUND OF THE INVENTION

[0002] Many solid fuel burning furnaces, such as wood burning furnaces have been designed to produce heat diffusing from a fire chamber to a surrounding heat exchanger surface. Some of these furnaces have been designed especially to heat water that can further be used to heat houses, commercial buildings, or swimming pools. In some prior art furnaces, the heat exchanger is configured so that the water to heat is directly in contact with the outer wall of a firebox. In these embodiments, the heat exchanger may then be so efficient that the firebox remains too cool to allow complete combustion of both the wood and the resulting gas. Therefore such a wood furnace produces relatively large quantities of heavy blackish smoke floating low on the ground. Therefore, such a wood burning swimming pool heater generates pollution and therefore cannot typically be used in residential area.

[0003] In addition, when a solid fuel burning furnace is used to heat water, heat exchange efficiency between the combustion gases produced when the solid fuel is burnt and the water needs to be relatively high so as not to waste the heat generated by the burning process. Many prior art solid fuel burning furnaces have been designed to reduce heat losses in a heat exchange unit attached to the furnace or to reduce the quantity of heat that is produced by the burning of the fuel and that escapes from the furnace. However, these furnaces are typically not optimally efficient and there is therefore room for improvement in the efficiency of heat transfer between the combustion bases produced by burning the solid fuel and the water to be heated.

[0004] Against this background, there exists a need for an improved solid fuel furnace. It is an object of the present invention to provide such a solid fuel furnace.

SUMMARY OF THE INVENTION

[0005] In a first broad aspect, the invention provides a furnace for burning solid fuel using surrounding air. The furnace includes a firebox for burning the solid fuel thereinto. The firebox defines a firebox bottom end and a firebox top end substantially opposed to the firebox bottom end. The firebox also defines a fuel receiving portion for receiving the solid fuel thereinto. The fuel receiving portion is located substantially adjacent to the firebox bottom end. An air-introducing system is provided for introducing the surrounding air into the firebox. The air introducing system includes a system inlet located outside of the firebox; a bottom system outlet located within the firebox substantially adjacent the firebox bottom end, the bottom system outlet being in fluid communication with the system inlet; a plurality of top system outlets located within the firebox substantially adjacent the firebox top end, the top system outlets being each in fluid communication with the system inlet, the top system outlets being distributed over an air distribution surface located substantially adjacent the firebox top end; and an air circulator located between the system inlet and the bottom system outlet and between the system inlet and the plurality of top system outlets. The air circulator is provided for drawing the surrounding air through the system inlet and blowing the drawn air into the firebox from the bottom system outlet and from the plurality of top system outlets.

[0006] The air blown through the bottom system outlet is used, at least in part, during the combustion of the solid fuel received within the fuel receiving portion and the air blown from the top system outlets allows for a completion a combustion of combustion gases and particles produced by the combustion of the solid fuel, the distribution of the top system outlets over the air distribution surface facilitating the substantially uniform completion of the combustion gases and particles produced by the combustion of the solid fuel.

[0007] In another aspect, the invention provides a method for facilitating the combustion of a solid fuel in a firebox, the firebox defining a firebox inner enclosure, the firebox inner enclosure defining an inner enclosure bottom portion and an opposed inner enclosure upper portion. The method includes injecting air both into the inner enclosure bottom portion and the inner enclosure top portions, the air being injected into the inner volume top enclosure through a plurality of air distribution apertures distributed over an air distribution surface.

[0008] In another broad aspect, the invention provides a furnace for burning a solid fuel using surrounding air, the furnace including a wall system defining a firebox for burning the solid fuel thereinto, the wall system being located peripherally relatively to the firebox, the firebox defining a firebox bottom portion and a firebox top portion substantially opposed to the firebox bottom portion. An air introducing system is provided for introducing the surrounding air into both the firebox bottom and top portions.

[0009] Advantageously, the proposed furnace is relatively easily manufacturable relatively cost effectively using known techniques and materials. In addition, the furnace is relatively easy to use and relatively easily connectable to an existing piping system that may bring water to be heated by the furnace to the furnace.

[0010] In addition, the top system outlets provide air into the firebox at a location allowing to complete the combustion of the combustion gases produced during the combustion of the solid fuel, which improves the energy efficiency of the furnace while reducing the amount of pollutants and smokes that may be produced when the solid fuel is burnt.

[0011] In some embodiments of the invention, the furnace has a generally layered structure that leads to a relatively large energy efficiency of the furnace. In addition, in some embodiments of the invention, the furnace is relatively efficient in the heat transfer between the combustion gases and the water to heat while having a furnace that is relatively simple and relatively easy to manufacture.

[0012] Other objects, advantages and features of the present invention will become more apparent upon reading of the following non- restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In the appended drawings,

[0014] Figure 1, in a perspective view, illustrates a furnace according to an embodiment of the present invention;

[0015] Figure 2, in a perspective cross-sectional view, illustrates the furnace of Fig. 2; [0016] Figure 3, in an alternative perspective cross-sectional view, illustrates the furnace of Figs. 1 and 2;

[0017] Figure 4, in a perspective partial cross-sectional view with parts removed, illustrates the furnace illustrated in Figs. 1 to 3;

[0018] Figure 5, in a perspective view with parts removed, illustrates the furnace illustrated in Figs. 1 to 4;

[0019] Figure 6, in a top partial cross-sectional view, illustrates the furnace of Figs. 1 to 5; and

[0020] Figure 7, in a perspective view, illustrates a portion of an air admission system for admitting air into a firebox of the furnace illustrated in Figs. 1 to 6.

[0021] Figure 8, in a perspective view, illustrates a portion of an alternative button system air admission for admitting air into a firebox of the furnace.

DETAILED DESCRIPTION

[0022] Fig. 1 illustrates a furnace 10 for burning a solid fuel using surrounding air (not shown in Fig. 1). Referring to Fig. 2, the surrounding air is generally indicated by the arrows marked as 12. The arrows marked as 12 illustrate the flow of the surrounding air 12 into the furnace 10 until it reaches a firebox 14 included in the furnace 10.

[0023] The firebox 14 is provided for burning a solid fuel (not shown in the drawings) thereinto. For example, and non-limitingly, the solid fuel may include wood, coal, corn or any other suitable solid fuel. The firebox 14 defines a firebox bottom end 16 and a firebox top end 18 substantially opposed to the firebox bottom end 16. The firebox 14 also defines a fuel receiving portion 20 for receiving the solid fuel thereinto. The fuel receiving portion 20 is located substantially adjacent the firebox bottom end 16.

[0024] The furnace 10 also includes an air-introducing system 22 for introducing the surrounding air 12 into the firebox 14. The air-introducing system 22 includes a system inlet 24 located outside of the firebox 14. A bottom system outlet 26 is located within the firebox 14 substantially adjacent the firebox bottom end 16. The bottom system outlet 26 is in fluid communication with the system inlet 24. A plurality of top system outlets 32 are located within the firebox 14 substantially adjacent the firebox top end 18. The top system outlets 32 are each in fluid communication with the system inlet 24. The top system outlets 32 are distributed over an air distribution surface 34 located substantially adjacent the firebox top end 18.

[0025] An air circulator (not shown in the drawings) is located between the system inlet 24 and the bottom system outlet 26. Also, the air circulator 36 is further located between the system inlet 24 and the plurality of top system outlets 32. The air circulator 36 is provided for drawing the surrounding air 12 through the system inlet 34 and blowing the drawn air 12 into the firebox 14 from the bottom system outlet 26 and from the plurality of top system outlets 32.

[0026] It should be understood that for the purpose of this document, the term "inlet" is used to cover both single apertures and a plurality of apertures through which the air may be drawn. In addition, the term "air circulator" refers both to a single physical entity such as, for example, a centrifugal fan, and to a plurality of physical entities such as, for example, a plurality of centrifugal fans.

[0027] In other words, the system inlet 24 and the air circulator may include distinct physically entities separate and, therefore, the surrounding air may be drawn through an aperture and blown through a first fan through the bottom system outlets 26 and drawn through another aperture and blown through using another fan through the top system outlets 32 without departing from the scope of the present invention.

[0028] In some embodiments of the invention, as better seen in Fig.

7, the bottom system outlet 26 is formed by an aperture located into a pipe 28 that is in fluid communication with a casing 37 (shown in Fig. 2) in which the air circulator is located. Also, in some embodiments of the invention, conventional deflectors 30 are provided substantially adjacent the bottom system outlets 26 so as to deflect the air 12 towards the solid fuel to be burnt.

[0029] In some embodiments of the invention, as better seen in Fig.

8, the bottom system outlets 26 are formed by an apertures located into a pipe 29 that is in fluid communication with a casing 37 (shown in Fig. 2) in which the air circulator is located.

[0030] Referring back to Fig. 2, the air 12 blown through the bottom system outlet 26 is used, at least in part, during the combustion of the solid fuel received within the fuel receiving portion 20. The air 12 blown from the top system outlets 32 allows for the completion of the combustion of combustion gases and particles produced by the combustion of the solid fuel, which are generally indicated by arrows 40. The distribution of top system outlets 32 over an air distribution surface 34, as opposed to a distribution on a line, facilitates a substantially uniform completion of the combustion of the combustion gases and particles 40 produced by the combustion of the solid fuel.

[0031] In some embodiments of the invention, the air injected though the top system outlets 32 produce a relatively fast increase in temperature inside the firebox 14. This increase in turn promotes the complete combustion of the combustion gases and particles 40. For example, the flow of air 12 through the top system outlets 32 is such that the temperature inside the firebox 14 reaches at least 650 Celcius, which has been found to be a temperature at which the combustion gases and particles 40 produced when burning the solid fuel, for example wood, ignite.

[0032] The firebox 14 is defined by a wall system 42. The wall system 42 is located peripherally relatively to the firebox 14. The firebox 14 defines a firebox bottom portion 44 located substantially adjacent the firebox bottom end 16 and a firebox top portion 46 located substantially adjacent the firebox top end 18 and therefore located substantially opposed to the firebox bottom portion 44. The air-introducing system 22 is therefore provided for introducing the surrounding air 12 into both the firebox bottom and top portions 44 and 46. Generally, the wall system 42 defines an air distribution layer 48 located above the firebox bottom portion 44. The top system outlets 32 extend between the air distribution layer 48 and the firebox 14. In other words, the top system outlets 32 extend between an air distribution enclosure and the firebox 14.

[0033] Having an air distribution layer 48 that is located above the firebox bottom portion 44 and, therefore, adjacent the firebox top end 18 and into the firebox top portion 46 allows to direct the air 12 blown through the top system apertures 32 substantially downwardly. This orientation of air jets thereby produced has been found to greatly improve the efficiency of the air distribution system 22 in providing for a relatively complete combustion of the combustion gases and particles 40 produced by the combustion of the solid fuel occurring within the firebox 14. In addition, since the air distribution layer 48 is located above the location wherein fuel is burnt, the air is therefore preheated before entering the combustion chamber, which further increases the efficiency of the combustion occurring within the firebox 14. Yet, furthermore, since the top system apertures 32 are distributed over a relatively large area, the combustion of the combustion gases and particles 40 occurs relatively uniformly over a substantially horizontal cross-section of the top portion 46 of the firebox 14.

[0034] Referring to Figs. 2 and 3, the wall system 42 further defines a heat exchange system 50 operatively coupled to the firebox 14 for recovering heat contained in combustion gases 40 produced by burning the solid fuel. For example, the heat exchange system 50 includes a combustion gas receiving chamber 52 in fluid communication relationship with the firebox 14 for receiving the combustion gases 40 produced by burning the solid fuel. A water containing chamber 54 is provided for containing water 55, the water-containing chamber 54 being in a heat exchange relationship with the combustion gas receiving chamber 52. For example, the water-containing chamber 54 is separated from the combustion gas-receiving chamber 52 by a wall 61 made of a heat conductive material such as, for example, a metal.

[0035] In some embodiments of the invention, the water containing chamber 54 is located peripherally relatively to the firebox 14 and the combustion gas receiving chamber 52. The combustion gas receiving chamber 52 being therefore located, at least in part, between the firebox 14 and the water-containing chamber 54.

[0036] It has been found that this arrangement of layers containing combustion gases 40 and the water 50 to be heated peripherally relatively to the firebox 14 reduces significantly energy losses through the walls of the firebox 14. Indeed, the heat produced within the firebox 14 must go either directly or indirectly through the water 55 contained in the water-containing chamber 54 before going out of the furnace 10 over a relatively large portion of the surface area of the wall system 42.

[0037] The firebox 14 includes a firebox outer wall 56 defining a firebox inner enclosure 58. The air-introducing system 22 includes an air distribution wall 60 operatively coupled to the firebox outer wall 56 so as to divide the firebox inner enclosure 58 into an air distribution enclosure, also referred to as the air distribution layer 48, extending substantially adjacent the firebox top end 18 between the firebox outer wall 56 and the air distribution wall 60. A combustion enclosure 62 is also created by the air distribution wall opposed to the air distribution enclosure. Therefore, the top system apertures 32 extend through the air distribution wall 60 between the air distribution enclosure and the combustion enclosure 62. The air distribution enclosure is then in fluid communication with the air circulator so as to allow to blow the air 12 through the top system apertures 32.

[0038] In some embodiments of the invention, the air distribution wall

60 is substantially planar and substantially horizontal. However, in other embodiments of the invention, the air distribution wall 60 may take any other suitable configuration.

[0039] In the embodiment of the invention shown in the drawings, the firebox outer wall 56 is substantially parallelepiped-shaped and defines a firebox top wall 64 located substantially adjacent to the firebox top end 18. The firebox outer wall also defines a firebox bottom wall 66 located substantially adjacent to the firebox bottom end 16 and a firebox peripheral wall 68 extending between the top and bottom walls 64 and 66. As seen in Fig. 2, the air distribution wall 60 is substantially parallel to the firebox top wall 64. However, in alternative embodiments of the invention, the air distribution wall 60 has any other suitable configuration.

[0040] In some embodiments of the invention, the top system outlets

32 have a substantially uniform density over a substantially horizontal cross- section of the firebox inner enclosure 58 in which the air distribution wall 60 is located. A substantially uniform density allows to distribute the air 12 substantially uniformly within the firebox top portion 46, therefore homogenizing the combustion of the combustion gases and particles produced when the solid fuel is burnt.

[0041] It has been found that having a substantially uniform density of from about 250 outlets per square meter to about 450 outlets per square meter with system outlet 32 having a diameter of from about 0.2 centimeters to about 0.4 centimeters produces relatively good results while keeping the complexity of the air distribution wall 60 at a reasonable level, and therefore keeping its manufacturing cost relatively inexpensive. For example, in some embodiments of the invention, the system outlets 32 have a density of about 350 outlets per square meter and have a diameter of about 0.3 centimeters.

[0042] In another way of seeing the density of system outlets 32 that produces optimal results, it has been found that having top system outlets 32 that together have an area of from about 0.2% to about 0.5% of the total area of the air distribution wall 60 produce good results in the homogeneity of combustion. In a specific embodiment of the invention, a value of 0.35% has been found to be optimal to produce a substantially complete combustion of the gases 40.

[0043] Since an objective of the air distributed by the air-distribution wall 60 is to burn incompletely combusted particles and gases 40, it would be expected that having a relatively small speed of the air injected within the firebox 14 to the top system outlets 32 would produce optimal results as this would lengthen the duration of the air 12/ combustion gases 40 interaction. However, experimentation showed that surprisingly, having a relatively high speed of the air 12 projected through the top system outlets 32 produced optimal results. In a specific embodiments of the invention, having a speed of from about 7 meters per second to about 12 meters per second has been found to produce good results and, more specifically, a speed of about 10 meters per second has been found to be optimal in combusting almost completely the combustion gases and particles produced when the solid fuel is burnt in a specific embodiment of the invention.

[0044] It should be noted that having very high air speeds would probably produce sub-optimal results as the air injected through the air distribution wall 60 would then not have an optimal temperature and air combustible substance mixture would be too rich, which would interact to produce sub-optimal combustion and energy production. Also, if a the speed of the air 12 injected through the top system outlets is such that a significant portion of the air 12 thereby injected reaches the solid fuel, the speed at which the combustion of the solid fuel occurs may be too fast and produce high temperatures within the firebox 14 that may cause damages to the wall system 42.

[0045] As better seen in Fig. 4, in some embodiments of the invention, the firebox 14 includes a combustion gas output tube 70 extending through the air distribution layer 48, the combustion gas output tube 70 defining an output tube inlet 71 in fluid communication relationship with the combustion volume, an output tube outlet 72 in fluid communication with the combustion gas receiving chamber 52 and an output tube passageway 75 extending therebetween.

[0046] In some embodiments of the invention, more than one combustion gas output tubes 70 are provided so as to increase and homogenize the transfer of combustion gases 40 from the firebox 14 to the combustion gas-receiving chamber 52.

[0047] The specific configuration of the combustion gas output tube which extends through the air distribution enclosure helps in pre-heating the air 12 before it is injected into the firebox 14, thereby increasing the efficiency of the final combustion of the combustion gases and particles 40.

[0048] Since the combustion gas output tubes 70 are located adjacent the top portion of the firebox 14, the combustion gases have a natural tending to go through this combustion gas output tube 70 through their natural buoyancy. In addition, since the air 12 is forced into the firebox 14 by the air circulator, a static pressure is created within the firebox 14 to push the combustion gases 40 through the combustion gas output tube 70 into the combustion gas-receiving chamber 52.

[0049] In some embodiments of the invention, the combustion gas receiving chamber 52 is configured so that the combustion gases 40 flow from the combustion output tubes 70 substantially horizontally substantially parallel to the firebox top wall 64, substantially downwardly substantially parallel to the firebox peripheral wall 68 and substantially horizontally substantially parallel to firebox bottom wall 66 towards a chamber gas outlet 73 that is located substantially adjacent the firebox bottom end 16. Therefore, the combustion gases 40 follow a relatively tortuous and long pathway before reaching a chamber gas outlet 73 that is itself connected to a chimney 74 for evacuating the combustion gases 40. Since this pathway is relatively tortuous and relatively long, the combustion gases 40 may transfer heat to the water 55 relatively efficiently. Also, in some embodiments of the invention, the water 55 flows within the water containing chamber 54 in a direction opposite to a direction in which the combustion gases 40 flow within the combustion gas receiving chamber 52, which also contributes to the heat exchange efficiency of the heat exchanging system 50.

[0050] In a specific example of implementation, the combustion gas receiving chamber 52 takes the form of a sleeve surrounding the firebox 14. Also, the water containing chamber 54 takes the form of a jacket surrounding, at least in part, the gas-receiving chamber. For example, the water containing chamber 54 is substantially U-shaped having two substantially downwardly extending portions extending from a substantially horizontal portion.

[0051] Referring to Fig. 2, in some embodiments of the invention, a thermal insulator 76 is located between the combustion enclosure 62 and the combustion gas receiving chamber 52. This helps in keeping a relatively hot atmosphere within the firebox 14 so as to increase the efficiency of the furnace 10. In some embodiments of the invention, the thermal insulator includes a refractory material, such as for example firebricks.

[0052] In some embodiments of the invention, the operation of the furnace 10 is controlled through a controller 80, seen for example in Fig. 1. The controller 80 controls the operation of the air circulator. The circulation of the air 12 by the air circulator depends upon the temperature of the water 55 contained in the water containing chamber 54, the rate of increase in temperature of the water 55 and the time for which the air circulator has been operating, among other parameters.

[0053] To that effect, the controller 80 includes a thermostat operatively coupled to the water containing chamber 55 and to the controller 80 for selectively stopping or starting the operation of the air circulator in response to the temperature of the water 55. For example, if the temperature of the water 55 increases beyond a predetermined temperature, the air circulator stops operating so as to stop the combustion occurring within the firebox 14. In other embodiments of the invention, if the temperature of the water 55 increases too rapidly, this could indicate a malfunction of the furnace 10 and the operation of the air circulator is therefore stopped to prevent a runaway situation that may damage the furnace 10.

[0054] In some embodiments of the invention, the air admission system 22 includes an air admission trap 78, seen in Fig. 2, located between the system inlet 24 and the top and bottom system outlets 26 and 32 for selectively preventing the surrounding air 12 from being blown through the top and bottom system outlets 26 and 32. The admission trap 78 is movable between an open configuration as shown in Fig. 2 and a closed configuration (not shown in the drawings). In the closed configuration, the admission trap 78 prevents the surrounding air from being be blown through the top and bottom system outlets 26 and 32.

[0055] In some embodiments of the invention, the controller 80 stops the operation of the air circulator after a predetermined amount of time has lapsed. Indeed, if air 12 circulates within the combustion enclosure 62 for longer than the predetermined amount of time, there is no more combustible material to be burnt and the air 12 has the potential to be circulated through the heat exchange system 50 and to reduce the temperature of the water 55 circulating through the water containing chamber 54. In some embodiments of the invention, it is the flow of air pushed by the air circulator that moves the admission trap 78 in the open configuration. In other embodiments of the invention, the admission trap 78 is motorized and the controller 80 may directly move the admission trap 78 to control the flow of air that reaches the firebox 14.

[0056] In some embodiments of the invention, the air circulator may be used to control the flow of air within the air

[0057] As shown in the drawings, the furnace 10 includes, in some embodiments of the invention, other features such as, for example, legs 84 supporting the furnace 10 away from the ground surface (not shown in the drawings). In addition, in some embodiments of the invention, an access door 86 is provided in the front wall portion to allow access into the firebox 14 to add fuel and remove ashes after the combustion has been completed.

[0058] Also, in some embodiments of the invention, a handling handle 90 extends substantially upwardly from the wall system 42 and allows to attach a crane or any other lifting apparatus to handle the furnace 10 during an installation process.

[0059] In some embodiments of the invention, a piping system 92, only part of which is shown in Fig. 1 , is connectable to the water containing chamber 54 for circulating the water 55 through the water containing chamber 54. An example of an application wherein this is desirable is when the furnace 10 is used to heat the water contained in a pool. For example, a pump typically conventionally included into a pool is used to circulate the water through the water containing chamber 54 so as to heat the water that is then sent back to the pool.

[0060] Referring to Fig 5, in some embodiments of the invention the furnace 10 is manufactured so that the portion of the wall system 42 that is opposed to the access door 86 may be removed. In these embodiments, this portion of the wall system 42 is attached to the remaining portion of the wall system 42 through fasteners and an insulating tube 94, seen in Fig 6, is inserted between these two portions of the wall system 42.

[0061] Although the present invention has been described hereinabove by way of preferred embodiments thereof, it can be modified, without departing from the spirit and nature of the subject invention as defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A furnace for burning a solid fuel using surrounding air, said furnace comprising:

- a firebox for burning the solid fuel thereinto, said firebox defining a firebox bottom end and a firebox top end substantially opposed to said firebox bottom end, said firebox also defining a fuel receiving portion for receiving the solid fuel thereinto, said fuel receiving portion being located substantially adjacent said firebox bottom end; and - an air introducing system for introducing the surrounding air into said firebox, said air introducing system including

- a system inlet located outside of said firebox;

- a bottom system outlet located within said firebox substantially adjacent said firebox bottom end, said bottom system outlet being in fluid communication with said system inlet;

- a plurality of top system outlets located within said firebox substantially adjacent said firebox top end, said top system outlets being each in fluid communication with said system inlet, said top system outlets being distributed over an air distribution surface located substantially adjacent said firebox top end; and

- an air circulator, said air circulator being located between said system inlet and said bottom system outlet, said air circulator being further located between said system inlet and said plurality of top system outlets, said air circulator being provided for drawing the surrounding air through said system inlet and blowing the drawn air into said firebox from said bottom system outlet and from said plurality of top system outlets;

- whereby the air blown through said bottom system outlet is used, at least in part, during the combustion of the solid fuel received within fuel receiving portion and the air blown from said top system outlets allows for the completion of the combustion of combustion gases and particles produced by the combustion of the solid fuel, the distribution of the top system outlets over said air distribution surface facilitating a substantially uniform completion of the combustion of the combustion gases and particles produced by the combustion of the solid fuel.

2. A furnace as defined in claim 1 , wherein said firebox includes a firebox outer wall defining a firebox inner enclosure, said air introducing system including an air distribution wall operatively coupled to said firebox outer wall so as to divide said firebox inner enclosure into - an air distribution enclosure extending substantially adjacent said firebox top end between said firebox outer wall and said air distribution wall; and

- a combustion enclosure in which said fuel receiving portion is located; - said top system apertures extending through said air distribution wall between said air distribution enclosure and said combustion enclosure, said air distribution enclosure being in fluid communication with said air circulator.

3. A furnace as defined in claim 2, wherein said air distribution wall is substantially planar and substantially horizontal.

4. A furnace as defined in claim 2, wherein said firebox outer wall is substantially parallelepiped-shaped and defines a firebox top wall located substantially adjacent said firebox top end, a firebox bottom wall located substantially adjacent said firebox bottom end and a firebox peripheral wall extending therebetween.

5. A furnace as defined in claim 4, wherein said air distribution wall is substantially parallel to said firebox top wall.

6. A furnace as defined in claim 5, wherein said system top outlets have a substantially uniform density over a substantially horizontal cross-section of said firebox inner enclosure in which said air distribution wall is located.

7. A furnace as defined in claim 6, wherein said substantially uniform density is from about 250 outlets/square meter to about 450 outlets/square meter.

8. A furnace as defined in claim 6, wherein said top system outlets have a diameter of from about 0.2 centimeters to about 0.4 centimeters.

9. A furnace as defined in claim 8, wherein said top system outlets have a diameter of about 0.3 centimeters.

10. A furnace as defined in claim 6, wherein said top system outlets occupy from about .2% to about .5% of an area of said air distribution surface.

11 A furnace as defined in claim 10, wherein said top system outlets occupy about .35% said area of said air distribution surface.

12. A furnace as defined in claim 1, further comprising a heat exchange system operatively coupled to said firebox for recovering heat contained in combustion gases produced by burning the solid fuel.

13. A furnace as defined in claim 12, wherein said heat exchange system includes

- a combustion gas receiving chamber in fluid communication relationship with said firebox for receiving the combustion gases produced by burning the solid fuel; and

- a water containing chamber for containing water, said water containing chamber being in a heat exchange relationship with said combustion gas receiving chamber.

14. A furnace as defined in claim 13, wherein said water containing chamber is located peripherally relatively to said firebox and said combustion gas receiving chamber, said combustion gas receiving chamber being located, at least in part, between said firebox and said water containing chamber.

15. A furnace as defined in claim 13, further comprising a thermal insulator located within said firebox for substantially thermally insulating said combustion gas receiving chamber from said firebox.

16. A furnace as defined in claim 13, wherein said air admission system includes an air admission trap located between said system inlet and said top and bottom system outlets for selectively preventing the surrounding air from being blown through said top and bottom system outlets, said air admission trap being movable between an open configuration allowing the surrounding air to be blown through said top and bottom system outlets and a closed configuration preventing the surrounding air to be blown through said top and bottom system outlets.

17. A furnace as defined in claim 16, further comprising a thermostat operatively coupled to said water containing chamber and to said admission trap for selectively moving said admission trap from said open configuration to said closed configuration upon a temperature of the water contained in said water containing chamber reaching a predetermined temperature.

18. A method for facilitating the combustion of a solid fuel in a firebox, the firebox defining a firebox inner enclosure, the firebox inner enclosure defining an inner enclosure bottom portion and an opposed inner enclosure upper portion, said method comprising injecting air both into said inner enclosure bottom portion and said inner enclosure top portion, the air being injected into said inner enclosure top portion through a plurality of air distribution apertures distributed over an air distribution surface.

19. A method as defined in claim 18, wherein the air is injected through the plurality of air distribution apertures at a speed of from about 7 m/s to about 12 meters/second.

20. A method as defined in claim 18, wherein the air is injected through the plurality of air distribution apertures at a speed of about 10 meters/second.

21. A furnace for burning a solid fuel using surrounding air, said furnace comprising: - a wall system defining a firebox for burning the solid fuel thereinto, said wall system being located peripherally relatively to said firebox, said firebox defining a firebox bottom portion and a firebox top portion substantially opposed to said firebox bottom portion; - an air introducing system for introducing the surrounding air into both said firebox bottom and top portions.

22. A furnace as defined in claim 21 , wherein said air introducing system includes

- a system inlet for drawing the surrounding air therethrough;

- a plurality of top system outlets, said top system outlets being distributed over an air distribution surface located substantially adjacent said firebox top portion; and

- an air circulator located between said system inlet and said plurality of top system outlets, said air circulator being provided for drawing the surrounding air through said system inlet and blowing the drawn air into said firebox from said plurality of top system outlets.

23. A furnace as defined in claim 22, wherein said wall system defines an air distribution layer located above said firebox bottom portion, said plurality of top system outlets extending between said air distribution layer and said firebox.

24. A furnace as defined in claim 21, wherein said wall system defines a heat exchange system operatively coupled to said firebox for recovering heat contained in combustion gases produced by burning the solid fuel.

25. A furnace as defined in claim 24, wherein said heat exchange system includes

26. A furnace as defined in claim 25, wherein said water containing chamber is located peripherally relatively to said firebox and said combustion gas receiving chamber, said combustion gas receiving chamber being located, at least in part, between said firebox and said water containing chamber.