Patent Publication Number: US-2003226561-A1

Title: Pellet furnace heating apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application claims the benefit of U.S. provisional application No. 60/259,249, filed Jan. 3, 2001. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] This invention relates to a heating apparatus operated by combustible pellets and more particularly, to a pellet furnace heating apparatus which utilizes combustible pelletized fuel such as wood pellets, corn and the like, as fuel. In one embodiment, the pellet furnace heating apparatus includes an enclosure and a furnace provided in the enclosure. A furnace air blower is adapted for blowing the burning fuel and increasing heat in the furnace. A hopper containing the solid fuel is connected to the furnace by means of a fuel delivery mechanism, which delivers the solid fuel from the hopper to the furnace. In another embodiment, the pellet furnace heating apparatus includes a burner having a combustion housing provided on a pilot housing, and a fuel delivery mechanism delivers solid fuel contained in a hopper to the combustion housing of the burner. A furnace air blower increases the heat of the burner by blowing air on the burning fuel.  
       [0004] Conventional fireplaces burn cords of wood to generate heat. In mild southern winters, a house of approzimately 2600 square feet in size uses about two cords of wood (the dimensions of a cord of wood are 4′×4′×8′), which will maintain a comfortable room temperature of approximately 72 degrees Fahrenheit at an annual cost of about $480.00. In contrast, the pellet furnace heating apparatus of this invention is capable of burning a smaller quantity of wood (about 2000 lbs.) in the form of wood pellets to maintain the same size house at a comparable temperature. The quantity of fuel costs between the two systems represents about ⅔ in savings if a wood pellet system is used. Accordingly, the pellet furnace heating apparatus of this invention will utilize approximately a ton of wood pellets, which costs $165.00 per ton (a ⅔ savings over regular wood), during a typical southern winter, and maintain an average room temperature of 72 degrees Fahrenheit.  
       [0005] The efficiency of the pellet furnace heating apparatus is due to a higher heat yield between a regular and a modified fireplace. A conventional fireplace maintains an approximate temperature of between 400 degrees to 500 degrees Fahrenheit in the firebox, and about 200 to 300 degrees Fahrenheit leaves the firebox through a 10″ flue pipe. Thus, conventional fireplaces retain about 200 degrees Fahrenheit, or about ⅓ of the heat produced, to heat a house. In contrast, the pellet furnace heating apparatus of this invention is capable of retaining about 500 degrees Fahrenheit to heat the house since the apparatus generates about 700 to 800 degrees Fahrenheit in the firebox and about 200 to 300 degrees Fahrenheit leaves the firebox through the system&#39;s 4″ exhaust pipe. The reason behind the higher efficiency in the modified fireplace is multifold. One is the fact that regular wood has more impurities, such as water, which reduces the quantity of heat produced, than wood pellets. Another reason is the design of the firebox in the apparatus, which allows for a more efficient way to burn the wood pellets. In addition, the apparatus of this invention is a better heat exchanger than conventional fireplaces.  
       [0006] The pellet furnace heating apparatus of this invention has many environmental advantages over conventional fireplaces. The apparatus of the invention emits little, if any, smoke due to the small quantity of water and impurities in the pellets. The apparatus of this invention is characterized by an automatic feeding system which can operate unattended for up to 24 hours or longer. In contrast, conventional fireplaces require more frequent attention or the fire will burn out and heat will thus be lost from the room or rooms heated by the fire. Furthermore, the apparatus of the invention generates few ashes and thus, reduces the amount of time and effort in cleaning the firebox of the apparatus after use. Conventional fireplaces generate approximately five gallons of ashes after burning wood for twelve hours, in contrast with the apparatus of this invention, which produces about a cup of ashes which can be cleaned up using a household vacuum cleaner.  
       [0007] The corn-burning embodiment of the pellet furnace heating apparatus is capable of generating approximately 1200 degrees to 1400 degrees Fahrenheit and emits no visible smoke, carbon monoxide or ashes. If six pounds of corn are used per hour, the system is capable of generating about 48,000 British Thermal Units (BTUs) per hour. A bushel of corn, at a cost of $2.50, will generate approximately 456,000 BTUs. The expense of operating a pellet furnace heating apparatus of the invention, using corn, is much more economical than a system which utilizes fossil fuels.  
       [0008] 2. Description of the Prior Art  
       [0009] Various types of fireplaces, stoves and combinations thereof are known in the art. Typical of the fireplace stove design is U.S. Pat. No. 4,074,679, dated Feb. 21, 1978, to John F. Jensen. The fireplace stove detailed in that patent includes an outer cabinet fitted with a combustion enclosure or chamber and a grate forming a clearance space, with an ash receptacle mounted in the lower end of the combustion enclosure for burning a combustible fuel. An air end is provided in the cabinet for emitting air to be heated into the clearance space and an air outlet in the cabinet discharges heated air from the clearance to a surrounding space. U.S. Pat. No. 4,185,612, dated Jan. 29, 1980, to Clifton F. Briner et al, details a “Heat Circulating Fireplace”. The fireplace includes a heat exchanger which transfers heat from the combustion gases of the fuel to an air flow circulated through the unit. Inlet and outlet air ducts are provided on each side of the heat exchanger module to conduct air to be heated into and away from the heat exchanger. U.S. Pat. No. 4,351,315, dated Sep. 28, 1982, to Thomas A. Babbage, includes a solid fuel boiler having a facia for radiant heat to pass into a living room, while the flue hopper and ash pan are accessible from another room or from outside the structure. U.S. Pat. No. 4,603,683 dated Aug. 5, 1986, to Richard D. Craver, includes a fireplace insert which has a back wall and outwardly diverging lateral walls to provide an access opening for fuel. The insert is constructed of sheet metal and has a face plate to form a closure over the access opening. Blowers move air through the insert to exchange heat between the burning fuel and the air stream. U.S. Pat. No. 5,014,682, dated May 14, 1991, to Payson, details a “Pellet Stove Mantel” with integral hopper, which mantel stores pelletized fuel in a continuous-feed hopper. The fuel may be dispensed from the mantel feed storage area into a conventional pellet-type furnace according to a selected flow rate. U.S. Pat. No. 5,331,943, dated Jul. 26, 1994, to W. H. Ko, details a “Wood Pellet Stove” which includes an enclosure, a burner, a heat exchanger, a waste gas exhaust system, a feed system, a cleaning apparatus and a control system. The burner includes a seat, a container, a bottom portion, a top member, two first pillars, two second pillars and an inlet pipe. The cleaning device includes three scraper members and each of the scraper members includes a scrape plate pipe rod and a hoop element. U.S. Pat. No. 5,680,855, dated Oct. 28, 1997, to W. H. Ko, details an “Indoor Fireplace” having a base, a feeding device, a combustion chamber and a ventilation apparatus. The base includes a sliding plate provided with a feed pipe provided in communication with the combustion chamber. The ventilation apparatus includes an air drawing apparatus, an air discharging apparatus and multiple air circulation ducts.  
       [0010] It is an object of this invention to provide a new and improved pellet furnace heating apparatus in various configurations for a variety of heating applications.  
       [0011] Another object of the invention is to provide a pellet furnace heating apparatus which is capable of heating homes, offices and other structures.  
       [0012] Still another object of this invention is to provide a pellet furnace heating apparatus which is characterized by an enclosure; a furnace provided in the enclosure; a furnace air blower provided in air communication with the furnace; a hopper for containing the solid fuel; and a fuel delivery mechanism connecting the hopper and the furnace for delivering the solid fuel to the furnace.  
       [0013] A still further object of the invention is to provide a pellet furnace heating apparatus including a hopper for containing the solid fuel; a burner having a pilot housing and a combustion housing provided on the pilot housing; a fuel delivery mechanism connecting the hopper and the combustion housing of the burner for delivering the solid fuel to the burner; and a furnace air blower provided in air communication with the pilot housing of the burner.  
       SUMMARY OF THE INVENTION  
       [0014] These and other objects of the invention are provided in a pellet furnace heating apparatus for burning a solid fuel, which pellet furnace heating apparatus in one embodiment includes an enclosure which houses a furnace. A furnace air blower is provided in air communication with the furnace for blowing the burning fuel and increasing heat in the furnace. A hopper is provided for containing the solid fuel, and a fuel delivery mechanism connects the hopper and the furnace for delivering the solid fuel to the furnace. In another embodiment, the pellet furnace heating apparatus includes a burner having a pilot housing and a combustion housing. A fuel delivery mechanism connects a hopper containing the solid fuel with the combustion housing of the burner for delivering the solid fuel to the burner. A furnace air blower is provided in air communication with the pilot housing of the burner for blowing the burning fuel and increasing the heat in the burner. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0015] The invention will be better understood by reference to the accompanying drawings, wherein:  
     [0016]FIG. 1 is a perspective view of a typical fireplace with the pellet furnace heating apparatus of this invention built therein and designed to direct heat from the fireplace;  
     [0017]FIG. 2 is a perspective view of the pellet furnace heating apparatus and fireplace illustrated in FIG. 1, more particularly illustrating ductwork connected to the pellet furnace heating apparatus for distribution of heated air throughout a structure;  
     [0018]FIG. 3 is a perspective, exploded view of one embodiment of the pellet furnace heating apparatus of this invention, more particularly illustrating the apparatus enclosure, the furnace box, burner chamber, burner plate, feed augers, air purge, heat exchanger, blower compartments and typical grilles;  
     [0019]FIG. 3A is a perspective view, partially in section, of a typical air purge system for preventing heat transmission to the feed drop tube elements of the feed augers during operation of the pellet furnace heating apparatus;  
     [0020]FIG. 3B is a sectional view, taken along line  3 B- 3 B of the air purge system illustrated in FIG. 3A;  
     [0021]FIG. 4 is a perspective view, partially in section, more particularly illustrating typical essential elements of the pellet furnace heating apparatus and more particularly illustrating hopper storage areas for the pellet fuel and the location of the feed augers in the enclosure;  
     [0022]FIG. 4A is a perspective view, partially in section, of a typical heat exchanger for mounting on the flue pipe of the pellet furnace heating apparatus and minimizing heat loss through the flue pipe;  
     [0023]FIG. 5 is a front perspective view of the pellet furnace heating apparatus illustrated in FIGS. 3 and 4, more particularly illustrating the opposite side of the enclosure and a second hopper storage of pellet fuel, along with a single hot air circulation blower provided in the cabinet;  
     [0024]FIG. 6 is a top sectional view of the pellet furnace heating apparatus illustrated in FIGS. 4 and 5, more particularly illustrating hot air circulation blower discharge lines extending from the hot air circulation blowers, and other details of the apparatus;  
     [0025]FIG. 7 is a rear sectional view of the pellet furnace heating apparatus illustrated in FIGS.  4 - 6 , more particularly illustrating a system of baffles for baffling air distributed through the enclosure from the hot air circulation blowers into the enclosure and/or ductwork provided in a structure;  
     [0026]FIG. 8 is a side sectional view, taken along section lines  8 - 8  in FIG. 7, of a typical furnace of the pellet furnace heating apparatus of this invention, more particularly illustrating baffles;  
     [0027]FIG. 9 is a side sectional view of the pellet furnace heating apparatus furnace illustrated in FIG. 8, further illustrating the enclosed burner chamber and insulation, with the baffles removed for brevity;  
     [0028]FIG. 10 is a perspective view of a typical burner chamber of the portable pellet furnace heating apparatus illustrated in FIGS.  3 - 5  and  9 , more particularly illustrating a typical furnace air blower system for furnishing combustion air to the burner chamber of the apparatus;  
     [0029]FIG. 11 is a sectional view taken along line  11 - 11  of the pellet furnace heating apparatus burner chamber illustrated in FIG. 10;  
     [0030]FIG. 12 is a top sectional view taken along section lines  12 - 12  in FIG. 11, of a typical shaped burner plate of the pellet furnace heating apparatus illustrated in FIGS.  1 - 7 , more particularly illustrating an illustrative spacial orientation of combustion openings;  
     [0031]FIG. 13 is a perspective view of a portable pellet furnace heating apparatus of this invention;  
     [0032]FIG. 14 is a side view of the portable pellet furnace heating apparatus illustrated in FIG. 13, more particularly illustrating a feed auger and blower system for automatically feeding pelletized fuel and air, respectively, into the burner chamber;  
     [0033]FIG. 15 is a perspective view of another embodiment of the pellet furnace heating apparatus;  
     [0034]FIG. 16 is a perspective view of a burner component of the pellet furnace heating apparatus illustrated in FIG. 15;  
     [0035]FIG. 17 is a perspective view, partially in section, of the burner illustrated in FIG. 16, more particularly illustrating interior components of the burner;  
     [0036]FIG. 18 is an inverted, perspective view of a combustion housing element of the burner illustrated in FIG. 16;  
     [0037]FIG. 19 is an exploded, perspective view of the burner;  
     [0038]FIG. 20 is a perspective view, partially in section, of an alternative embodiment of the pellet furnace heating apparatus illustrated in FIG. 15, more particularly illustrating a steam generator mounted in the apparatus;  
     [0039]FIG. 21 is a perspective view of the steam generator illustrated in FIG. 20, removed from the apparatus for clarity;  
     [0040]FIG. 22 is a transverse sectional view, taken along section lines  22 - 22  in FIG. 21, of the steam generator;  
     [0041]FIG. 23 is a perspective view of a typical outdoor cooker, with a pellet furnace heating apparatus (not illustrated) of this invention connected to the cooker;  
     [0042]FIG. 24 is a front view of an air vent component on the smoking chamber of the cooker illustrated in FIG. 23;  
     [0043]FIG. 25 is a longitudinal sectional view, taken along section lines  25 - 25  in FIG. 23, of the cooker;  
     [0044]FIG. 26 is a perspective view of a pellet furnace heating apparatus of this invention, connected to the cooker of FIG. 23 for heating the cooker;  
     [0045]FIG. 27 is a sectional view, taken along section lines  27 - 27  in FIG. 26, of the pellet furnace heating apparatus and cooker illustrated in FIG. 26;  
     [0046]FIG. 28 is a side perspective view of a portable embodiment of the pellet furnace heating apparatus;  
     [0047]FIG. 29 is a sectional view, taken along section lines  29 - 29  in FIG. 28, of the pellet furnace heating apparatus;  
     [0048]FIG. 30 is a front perspective view of the pellet furnace heating apparatus illustrated in FIG. 28;  
     [0049]FIG. 31 is an exploded, front perspective view of the pellet furnace heating apparatus of FIG. 28, more particularly illustrating mounting of an air vent housing at a selected height on the apparatus; and  
     [0050]FIG. 32 is a front perspective view, partially in section, of the pellet furnace heating apparatus, with the air vent housing mounted in the uppermost position on the apparatus. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0051] Referring initially to FIGS.  1 - 3  of the drawings, in one embodiment of the invention, the pellet furnace heating apparatus is generally illustrated by reference numeral  1  and can be included in a fireplace  30 , illustrated in phantom in FIG. 1 and typically constructed of bricks  31 . As illustrated in FIG. 3, the pellet furnace heating apparatus  1  includes an enclosure  2  having a pair of pellet storage hoppers  3  at opposite ends thereof. Each pellet storage hopper  3  is typically provided with a pellet access panel  4  for loading pellet fuel  6  (FIG. 1) into the pellet storage hopper  3 . A blower compartment  8  is provided beneath each pellet storage hopper  3  in the enclosure  2 . A furnace  12  of the pellet furnace heating apparatus  1  includes a furnace box  13 , which is contained in the enclosure  2  and fitted with insulation  14 , and a burner chamber  15  is seated in the center of the furnace box  13 . Air is introduced into the burner chamber  15  through a furnace air supply line  18  that connects by means of a fitting  18   a  to a burner air plenum  16   a,  provided in the burner chamber  15 , and a valve  18   b  serves to regulate the flow of air through the furnace air supply line  18 . A pair of feed augers  19 , each having an auger feed tube  20  which angles upwardly from the corresponding pellet storage hopper  3  and a feed drop tube  23  which extends dowwardly from each auger feed tube  20 , are mounted on the enclosure  2  for the purpose of feeding pellet fuel  6  (FIG. 1) from the pellet storage hoppers  3 , into a fire  11  in the burner chamber  15  as illustrated in FIG. 1 and as further hereinafter described. Air is circulated around the furnace  12  as hereinafter described and is heated by the fire  11  in the burner chamber  15 . In one embodiment of the invention, illustrated in FIG. 1, some of the heated air is blown from the enclosure  2  through a pair of hot air ducts  43 , then through respective side grilles  34  into an enclosure or room which accommodates the fireplace  30 . In another embodiment of the invention illustrated in FIGS. 2 and 3, some of the heated air is blown from the enclosure through a pair of vertical hot air pipes  42  and a pair of respective extended hot air ducts  43   a,  for purposes hereinafter described. In both embodiments, the remaining air circulating around the furnace  12  may be blown from the enclosure  2  through a grille opening  32   a  and a furnace box grille  32 . The products of combustion of the pellet fuel are expelled through a flue pipe  35  which extends from the burner chamber  15  and through a chimney  46  (FIG. 2). A pair of blower compartment grilles  33  are designed to close each blower compartment  8 . The pellet access panels  4  are provided in the fireplace  30  for replenishing the supply of pellet fuel  6  in the enclosure  2  behind the bricks  31 , also as further hereinafter described.  
     [0052] Referring again to FIG. 2 of the drawings, in one embodiment of the invention, the pair of extended hot air ducts  43   a  joined to the respective hot air pipes  42  of the pellet furnace heating apparatus  1  facilitate a flow of heated air throughout a structure  45  and distribution of the heated air into the various rooms of the structure  45  through air registers  44 . In the pellet furnace heating apparatus  1  illustrated in FIG. 2, hot air may also be ejected through the furnace box grille  32  for the purpose of directly heating the room in which the fireplace  30  is located.  
     [0053] Referring to FIGS.  3 - 7  and  12  of the drawings, each of the blower compartments  8  provided in the enclosure  2  on each side of the furnace  12  houses a furnace air blower  9  that supplies air to the burner chamber  15  through the furnace air supply line  18 . A pair of hot air circulation blowers  10  are provided in opposite ones of the blower compartments  8  for circulating air through corresponding hot air blower discharge lines  10   a,  around the furnace box  13  and through either the furnace box grille  32 , seated in the furnace box opening  13   a  (FIG. 3), and the side grilles  34  as illustrated in FIG. 1, or through the furnace box grille  32  and a pair of extended hot air ducts  43   a,  as heretofore described with respect to FIG. 2. Accordingly, it will be appreciated by those skilled in the art that the hot air pipes  42  are optional and are normally only provided in the pellet furnace heating apparatus  1  as illustrated in FIGS. 2 and 3 for the purpose of connecting the pellet furnace heating apparatus  1  to the extended hot air ducts  43   a  in a structure  45 . Otherwise, the hot air pipes  42  can be eliminated from the pellet furnace heating apparatus  1  and the pellet furnace heating apparatus  1  operates as illustrated in FIG. 1 with direct heat and without connection to the extended hot air ducts  43   a.    
     [0054] A shaped burner plate  16  is mounted in the burner chamber  15 , typically by welding and the burner plate  16  is provided with multiple air openings  17  of selected size, number and spacing, as further illustrated in FIG. 12. In one embodiment of the invention, air openings  17  are provided in the burner plate  16  and the air openings  17  are arranged in a staggered configuration, as further illustrated in FIG. 12 and as further hereinafter described. Accordingly, air which is introduced into the burner chamber  15  beneath the burner plate  16  through the furnace air supply line  18  to the burner air plenum  16   a  by operating the furnace air blower  9 , supports the combustion of pellet fuel  6  which is dispensed onto the burner plate  16  from the feed drop tube elbows  24  of the feed drop tube  23  elements of the feed augers  19 . As illustrated in FIGS. 4 and 5, the pellet fuel  6  is stored in the pair of pellet storage hoppers  3  on a fuel support  7  in the interior of opposite ends of the enclosure  2 , and the pair of auger feed tubes  20  of corresponding feed augers  19  extend through the enclosure  2  into the pellet storage hoppers  3 , and terminate at an auger motor  22 . An auger  21  is provided in each of the auger feed tubes  20 , and the tops of the auger feed tubes  20  terminate in a tube end plate  20   a,  attached to the auger feed tube  20 , by means of end plate bolts  20   b  for servicing or replacing the auger  21 . The pair of feed drop tubes  23  of the respective feed augers  19  are attached to the upper ends of the respective auger feed tubes  20  and extend downwardly through the enclosure  2  to the burner chamber  15 , as heretofore described. Accordingly, operation of the auger motors  22  causes each of the augers  21  in the respective auger feed tubes  20  to turn and to lift the pellet fuel  6  that contact the respective augers  21  through a feed tube access opening  20   c  in each auger feed tube  20 , upwardly, for spilling over into the respective feed drop tubes  23 . The pellet fuel  6  then drops by gravity through each feed drop tube  23  and through an air purge  25 , which may be provided on each of the feed drop tubes  23 , into the burner chamber  15  and onto the burner plate  16 , through the feed drop elbows  24 . It will be appreciated by those skilled in the art that the rate of feed of pellet fuel  6  to the burner chamber  15  and burner plate  16  can be controlled by the rate of rotation of each of the augers  21  in the feed augers  19 . Accordingly, the auger motors  22  are designed to operate at various speeds and appropriate wiring (not illustrated) known to those skilled in the art may be connected to the auger motors  22  for this purpose.  
     [0055] As further illustrated in FIGS. 3, 3 a  and  3   b,  the air purge  25  is characterized by a purge pipe  26  that inserts concentrically over each feed drop tube  23  on each of the feed augers  19  and the inside diameter of the purge pipe  26  is larger than the outside diameter of the feed drop tube  23 , to create an annulus  28  which is blocked at both ends by an annulus seal  29  (FIG. 3B). A purge air feed line  27  terminates at one end in the purge pipe  26  as further illustrated in FIG. 3B and the opposite end of the purge air feed line  27  is connected to the furnace air supply line  18  which is, in turn, connected to the discharge of the furnace air blower  9 , as heretofore described. Accordingly, referring again to FIG. 3B, the pellet fuel  6  flows by gravity downwardly through the drop tube bore  23   a  of the feed drop tube  23  to prevent a flow of heat that would normally travel upwardly from the furnace  12  through the feed drop tubes  23 . The heat is impeded in this upward flow by the reverse flow of air from the purged air feed line  27 , through the annulus  28  and the purge opening  28   a  in the feed drop tube  23 , between the annulus seals  29 .  
     [0056] Referring again to FIGS.  3 - 7  of the drawings, the pellet fuel  6  is introduced for storage into the pellet storage hoppers  3 , located in opposite sides of the enclosure  2  and closed by a hopper top  3   a,  typically by means of pellet access panels  4 , typically attached to the front portion of the enclosure  2  by means of pellet access panel hinges  5 .  
     [0057] Referring now to FIGS. 3, 4 and  4   a  of the drawings, in another embodiment of the invention a flue pipe heat exchanger  36  is mounted in the flue pipe  35  and as illustrated in FIG. 4A, the hot gases from the burner chamber  15  and furnace  12  circulate on the shell side of the flue pipe heat exchanger  36 , while air is introduced into the tube side of the flue pipe heat exchanger  36  by means of an inlet air line  40 , attached to one of two end plates  37  that close the ends of the flue pipe heat exchanger  36 . Tubes  38  may be provided longitudinally in the flue pipe heat exchanger  36  and receive the air from the inlet air line  40 , and heat is exchanged between the upward-flowing hot combustion gases in the flue pipe  35  and the air in  39  flowing inside the tubes  38 . The heated air out  39   b  exits the flue pipe heat exchanger  36  through the opposite end plate  37  and may directed into a structure or into a hot air duct  43 , as illustrated in phantom.  
     [0058] Referring to FIGS. 6, 8 and  9  of the drawings, the furnace  12  and burner chamber  15  of the pellet furnace heating apparatus of this invention are more particularly illustrated, with side air baffles  49  and rear air baffles  50  provided in the furnace  12 , for the circulation of air to be heated by combustion of pellet fuel (not illustrated) in the burner chamber  15 . The feed drop tube elements  23  of a feed auger  19  (not illustrated in FIGS. 8 and 9) are further illustrated for supplying pellet fuel from a source to the burner chamber  15 . As described above, the flue pipe  35  is designed to receive combustion gases from the pellet fuel burned in the burner chamber  15 , which gases exit the burner chamber  15  at about 800° F. through burner chamber vents  15   a,  illustrated in FIG. 9, circulate through an air circulation opening  12   a  between the insulation  14  and the inside surface of the enclosure  2 . As further illustrated in FIG. 8, the side air baffles  49  and rear air baffles  50  are designed to project from the furnace  12  in various configurations in order to facilitate a flow of air around and over the baffles and effect optimum heat transfer between the hot furnace  12  and the air, as heretofore described with respect to FIGS.  1 - 7  of the drawings. The temperature of the pellet fuel  6  consumed in the burner chamber  15  is elevated by introduction of air into the burner chamber  15  through the furnace air supply line  18  and the fittings  18   a,  as heretofore described with respect to the pellet furnace heating apparatus illustrated in FIGS.  1 - 7 . The heat output of the furnace  12  is controlled by the rate of flow of pellet fuel  6  through the feed drop tubes  23  into the burner chamber  15  and by the flow rate of air through the race air supply line  18 , into the burner chamber  15 .  
     [0059] Referring now to FIGS. 10, 11 and  12  of the drawings, the burner chamber  15  is detailed, with a pair of the feed drops tubes  23  provided with feed drop tube elbows  24 , for directing pellet fuel  6  (illustrated in FIG. 11) onto the perforated burner plate  16 . The burner plate  16  may be provided with a burner plate bend  16   b  that defines an upper burner plate  16   c  and a smaller lower burner plate  16   d.  It has been found by experimentation that the upper burner plate  16   c  should be larger than the lower burner plate  16   d.  However, the upper burner plate  16   c  can be the same size as or smaller than the lower burner plate  16   d.  Furthermore, the upper burner plate  16   c  typically contains 124 openings  17 , staggered as indicated in FIG. 12, while the lower burner plate  16   d  typically contains 63 openings  17 , also staggered as illustrated in FIG. 12. However, it is understood that any desired number of openings  17  can be provided in the upper burner plate  16   c  and the lower burner plate  16   d  depending upon the desired heating characteristics of the burner plate  16 . As described with respect to the pellet furnace heating apparatus  1  illustrated in FIGS.  1 - 9 , a furnace air blower  9  serves to supply air to the burner chamber  15  through the furnace air supply line  18  and fittings  18   a  attached to the burner air plenum  16   a.    
     [0060] Referring now to FIGS. 13 and 14 of the drawings, a portable pellet furnace heating apparatus  51  is illustrated and has a vent housing  58  mounted on an enclosure  2  and multiple hot air vents  57  provided on the vent housing  58 . The enclosure  2  is further provided with a hinged or fixed pellet access panel  4  for loading pellet fuel (not illustrated) into the enclosure  2 , and a feed auger  19  (illustrated in phantom in FIG. 14) is provided in the enclosure  2  and extends upwardly into the vent housing  58  for transferring the stored pellet fuel from the enclosure  2 , through the feed drop tube  23  and into the burner chamber  15  at a controlled rate, as heretofore described. The flue pipe  35  extends from the burner chamber  15  in order to release the hot combustion gases from the burner chamber  15 . A furnace air blower  9  is also illustrated in phantom and is connected to the burner chamber  15  (illustrated in phantom in FIG. 14), by means of a furnace air supply line  18 , also illustrated in phantom, for supplying air to the burner chamber  15  and increasing the heat of combustion of the pellet fuel, as heretofore described. A door  54  is hinged the enclosure  2  by means of door hinges  55  and includes a door handle  56  for accessing the burner plate  16  in the burner chamber  15 . A door recess  54   a  may be provided in the enclosure  2  to recess the door  54  at least partially into the enclosure  2  and further seal the burner chamber  15  during operation of the portable pellet furnace heating apparatus  51 . Portability of the portable pellet furnace heating apparatus  51  is provided by means of rollers  53 , mounted on roller brackets  53   a  as further illustrated in FIGS. 13 and 14.  
     [0061] Referring next to FIGS.  15 - 19  of the drawings, in another embodiment of the invention the pellet furnace heating apparatus is generally illustrated by reference numeral  101  and is particularly suitable for burning corn kernels (not illustrated). In one embodiment, the pellet furnace heating apparatus  101  includes a base  107 , on which is mounted a housing  106  provided with an upper, pellet storage hopper  102 , having a fuel support  7 , and a lower, blower compartment  105  which contains a burner air blower  115 . The interior of the pellet storage hopper  102  is typically accessed by raising a hopper lid  103  on the pellet storage hopper  102 , to facilitate placing corn kernels (not illustrated) or other pellet fuel into the pellet storage hopper  102 . Alternatively, the pellet storage hopper  102  may be fitted with a pellet access panel  4  (FIG. 13) to achieve the purpose. An upward-standing burner housing  108  having an upper housing opening  108   a  is provided on the base  107 , and the burner base  122  of a burner  121  rests on the base  107  inside a burner opening  109  of the burner housing  108 . As illustrated in FIGS.  16 - 19 , the burner base  122  of the burner  121  typically supports a pilot housing  123  having a pilot housing interior  124  (FIG. 17). A pilot valve  125  inside the pilot housing interior  124  is connected to a burner fuel source (not illustrated) through a fuel line  127  which extends from the pilot housing interior  124  of the pilot housing  123 . A combustion housing  130 , having a combustion housing interior  132  the bottom of which is typically fitted with a dish-shaped or concave combustion dish  131 , is mounted on the pilot housing  123  and provided with multiple flame openings  131   a  arranged in a selected pattern and spacing. As illustrated in FIGS. 17 and 19, in one embodiment the combustion dish  131  is fitted with a flare plate  128  disposed directly above the bottom of the combustion dish  131 , for purposes hereinafter described. In another embodiment (not illustrated) of the pellet furnace heating apparatus  101 , the base  107  is omitted and the housing  106 , the burner base  122  of the burner  121 , and the burner housing  108  are supported on the ground or other supporting surface (not illustrated).  
     [0062] As further illustrated in FIG. 15, the burner air blower  115  in the blower compartment  105  of the housing  106  is connected to the pilot housing interior  124  of the burner  121  by means of a burner air supply line  116 , through a fitting  118  and a fitting nipple  119  extending from the pilot housing  123 . The burner air supply line  116  is typically fitted with an air flow control valve  117  for controlling the flow rate of air through the burner air supply line  116  as hereinafter described. As illustrated in FIG. 17, a flame guard  129  is typically provided on the pilot valve  125  to shield a flame  120 , issuing from the pilot valve  125 , from air flowing into the pilot housing interior  124  through the fitting nipple  119  of the burner air supply line  116 . An auger feed tube  20  of a feed auger  19  angles upwardly from inside the pellet storage hopper  102  and is fitted with a feed drop tube  23 , typically having an air purge  25  fitted with a purge air feed line  27 , for delivering by gravity the corn kernels or other feed (not illustrated) from the auger feed tube  20  into the combustion dish  131  of the combustion housing  130  at a controlled rate, as heretofore described. One or multiple pellet deflector plates  133  may be provided in the combustion housing interior  132  to ensure deposit of the pellet fuel into the middle of the combustion dish  131  from the feed drop tube  113 .  
     [0063] In typical operation of the pellet furnace heating apparatus  101 , the corn kernels or other pellet fuel is delivered at a controlled rate through the auger feed tube  20  of the feed auger  19  and onto the combustion dish  131  of the burner  121  through the feed drop tube  23 , and the flare plate  128  typically spreads the flame  120  generated by the pilot valve  125  outwardly to the flame openings  131   a  in the combustion dish  131 . As the corn kernels or pellet fuel burns in the combustion housing interior  132 , air flowing from the burner air blower  115  and into the pilot housing interior  124  through the burner air supply line  116  increases the heat of combustion of the pellet fuel in the combustion housing interior  132 , as heretofore described. The heat generated by the burning corn kernels or pellet fuel in the combustion dish  131  escapes from the combustion housing interior  132  and burner housing  108  through the housing opening  108   a  of the burner housing  108 . Referring again to FIG. 19 of the drawings, while the combustion housing  130  may be removably mounted on the pilot housing  123  by engaging combustion housing threads  130   a  with pilot housing threads  123   a,  it is understood that the combustion housing  130  may be removably or fixedly mounted on the pilot housing  123  by any suitable techniques known to those skilled in the art.  
     [0064] Referring next to FIGS.  20 - 22  of the drawings, in another embodiment of the pellet furnace heating apparatus generally illustrated by reference numeral  134 , the pellet furnace heating apparatus  101  heretofore described with respect to FIGS.  15 - 19  is fitted with a flue pipe steam generator  135  for generating steam, as hereinafter described. Accordingly, the burner housing  108  of the pellet furnace heating apparatus  134  is provided with a top plate  143  for supporting an upper, steam housing  138  of the flue pipe steam generator  135 . As illustrated in FIGS. 21 and 22, multiple, peripheral steam tubes  137  and a central steam tube  142  connect the steam housing  138  of the flue pipe steam generator  135  to a lower, water reservoir  136  which, as illustrated in FIG. 20, is disposed just above the combustion housing  130  of the burner  121 . A water conduit  139 , typically fitted with one or multiple water flow control valves  140 , is connected to a water source (not illustrated) and extends from fluid communication with the steam housing  138 . A steam conduit  141  further extends from the steam housing  138  for conveying steam from the steam housing  138  to a steam turbine (not illustrated) or other destination for use of the steam, in operation of the pellet furnace heating apparatus  134  as hereinafter described. Accordingly, in typical operation the water reservoir  136  of the flue pipe steam generator  135  is initially filled with water through the water conduit  139 , by opening the water flow control valve or valves  140 . This facilitates flow of water from the water conduit  139 , through the steam housing  138 , steam tubes  137  and central steam tube  142  and into the water reservoir  136 . Upon subsequent operation of the burner  121 , the water contained in the water reservoir  136  is heated to a boil, and steam rises upwardly from the water reservoir  136 , through the steam tubes  137  and central steam tube  142  and steam housing  138 , and through the steam conduit  141  to a steam turbine (not illustrated) or other destination for use of the steam The water reservoir  136  is filled with an additional supply of water, as needed, by operation of the water flow control valves  140  on the water conduit  139 , as heretofore described.  
     [0065] In yet another preferred embodiment of the invention, a cooker  75  is illustrated in FIGS.  23 - 27  of the drawings and a pellet furnace heating apparatus  101  heretofore described with respect to FIGS.  15 - 19  delivers cooking heat to the cooker  75 . The cooker  75  includes a typically cylindrical outer drum  76  and a cylindrical inner drum  77 , provided inside the outer drum  76  to create a drum annulus  78  of selected size. A pair of annulus vents  79  are mounted on the outer drum  76  to facilitate removal of combustion gases from the drum annulus  78 , as hereinafter described. The inner drum  77  defines a cooking chamber  80  which is fitted with a cooking chamber vent  81 . In one embodiment, multiple rotisserie racks  82  are mounted on a motor shaft  73  which extends between a pair of rotatable rotisserie wheels  82   a  at opposite ends of the cooking chamber  80 , and the motor shaft  73  is engaged by a rotisserie motor  72  which is mounted on one end of the cooker  75 , as further illustrated in FIG. 25, and rotates the motor shaft  73  and the rotisserie racks  82  in the cooking chamber  80 . In another embodiment (not illustrated), one or multiple food support racks (not illustrated) are mounted in the cooking chamber  80  in conventional fashion. A cooker frame  83  supports the outer drum  76  and the inner drum  77 , as well as a smoking chamber  88 , as further illustrated in FIGS. 23 and 25. The cooker frame  83  includes grip arms  84  projecting from one end thereof, and a cooker door  85  is fitted to the outer drum  76  and covers an opening that extends through the inner drum  77  and accesses the cooking chamber  80  as it mounts on a cooker door hinge  87 , as illustrated in FIG. 23. A cooker door handle  86  facilitates opening and closing of the cooker door  85  on the cooker door hinge  87 .  
     [0066] The smoking chamber  88  is fitted with a smoking chamber door  89 , hinged to the smoking chamber  88  by means of a smoking chamber door hinge  89   a  and fitted with a smoking chamber door handle  90 , for accessing the interior of the smoking chamber  88 . An air vent  91  is provided in one end of the smoking chamber  88  to allow a selected flow of air to enter the smoking chamber  88 . The air vent  91  (FIG. 24) includes air vent openings  92  and corresponding rotating air vent shutters  93  attached to a shutter pin  94  and pivotally mounted on a pivot bolt  100 , to facilitate opening and closing the air vent openings  92  by manipulating the shutter pin  94  and rotating the air vent shutters  93  on the pivot bolt  100  to align with or clear the air vent openings  92  and provide more or less smoking action inside the smoking chamber  88 . An accessory platform  95  may also be provided on the cooker frame  83 , and the cooker  75  may be made portable by the addition of wheels  96  mounted to a wheel axle  97 . A smoking chamber vent  98  communicates between the interior of the smoking chamber  88  and the cooking chamber  80  of the inner drum  77 , to facilitate a flow of smoke from burning fuel such as mesquite wood, hickory or the like, in the smoking chamber  88 , through the smoking chamber vent  98  into the cooking chamber  80  to smoke the food  99  resting on the rotisserie rack or racks  82 . This smoke exits the cooking chamber  80  through the cooking chamber vent  81 .  
     [0067] The cooker  75  is connected to the burner housing  108  of the pellet furnace heating apparatus  101  by means of a hot air conduit  165 , one end of which is typically connected to a top plate  169  on the upper end of the burner housing  108  and the other end of which communicates with the drum annulus  78  at the bottom of the cooker  75 , as illustrated in FIG. 27. In one embodiment of the invention, a horizontal supporting segment  165   a  is provided in the hot air conduit  165 , and a hot plate  166 , adapted for supporting a pan  168  or other cooking vessel, as further illustrated in FIG. 27, is welded or otherwise fixedly or removably mounted on the upper surface of the supporting segment  165   a,  and an upward-standing flange  167  may be provided along the perimeter of the hot plate  166 . In another embodiment of the invention, the hot plate  166  and flange  167  are omitted, and a hot air conduit  165  of any desired configuration connects the burner housing  108  of the pellet furnace heating apparatus  101  to the cooker  75 . In application, the corn kernels or pellet fuel (not illustrated), delivered to the combustion housing  130  of the burner  121  from the pellet storage compartment  104  of the pellet storage hopper  102  through the auger feed tube  20  and feed drop tube  23  of the feed auger  19 , are burned in the burner  121 , generating a fire  11  which creates heat of sufficient intensity to cook the food  99  inside the cooker  75  as the hot combustion gases flow from the burner housing  108 , through the hot air conduit  165  and into the drum annulus  78  of the cooker  75 . Smoke, heat and other products of combustion flow from the drum annulus  78  and through the annulus vents  79  of the cooker  75 . Simultaneously, heat from the supporting segment  165   a  of the hot air conduit  165  is conducted by the hot plate  166 , which heats the pan  168  and contents thereof. The rotisserie racks  82 , supporting the food  99  inside the cooking chamber  80  of the cooker  75 , can be rotated around the rotisserie shaft  73  inside the cooking chamber  80  by operation of the rotisserie motor  72 , as desired.  
     [0068] Referring next to FIGS.  28 - 32  of the drawings, in still another embodiment the pellet furnace heating apparatus of this invention is generally illustrated by reference numeral  145  and includes a housing  106  which contains a pellet storage hopper  102 , typically fitted with a hopper lid  103  or alternatively, a pellet access panel  4  (FIG. 13), and a bottom blower compartment  105  which contains a burner air blower  115 , as heretofore described with respect to the pellet furnace heating apparatus  101  in FIGS.  15 - 19 . The housing  106  is mounted along with an enclosure  148  on a base  146  typically provided with a pair of spaced-apart forklift openings  146   a,  the purpose of which will be hereinafter described. As illustrated in FIG. 29, the enclosure  148  houses a burner chamber  149  and a blower chamber  160 , separated by a partition  152  having a partition opening  152   a  which establishes communication between the burner chamber  149  and the blower chamber  160 . An air flow opening  150 , selectively closed by a hinged door  151 , is provided in a rear enclosure panel  153  of the burner chamber  149  of the pellet furnace heating apparatus  145 . A burner  121 , such as that heretofore described with respect to FIGS.  15 - 19 , rests on the base  146  inside the burner chamber  149 . Multiple closure panels  154  and a vent housing support panel  157  are mounted on the enclosure  148  typically by means of multiple bolts  158  threaded into respective bolt openings  159  in the enclosure  148 , which closure panels  154  in combination with a vent housing support panel  157  close the blower chamber  160  of the enclosure  148 . An air vent housing  155 , having a selected configuration and typically fitted with multiple air vents  156 , is mounted along with one or multiple air distribution blowers  147  on the vent housing support panel  157 , which vent housing support panel  157  and air vent housing  155  can be removably mounted at selected heights on the enclosure  148  for purposes hereinafter described. In operation of the pellet furnace heating apparatus  145 , as illustrated in FIG. 29, combustion of corn kernels or pellet fuel (not illustrated) in the burner  121  causes hot combustion gases to rise upwardly from the burner  121  into the burner chamber  149 , such that air drawn into the burner chamber  149  through the air flow opening  150  thereof is heated and flows through the partition opening  152   a  in the partition  152 , as indicated by the arrows. The heated air is then drawn into the air distribution blower or blowers  147  on the vent housing support panel  157 , and the air distribution blower or blowers  147  blow the air through the air vents  156  of the air distribution blower or blowers  147 . It will be appreciated from a consideration of FIG. 31 that the vent housing support panel  157  and any one of the closure panels  154  can be removed and interchanged in position on the enclosure  148  to facilitate mounting the air vent housing  155  at a selected height on the enclosure  148 , as needed. Accordingly, the pellet furnace heating apparatus  145  is particularly suitable for heating the interior of poultry houses in cold weather, since the pellet furnace heating apparatus  145  can be moved from one location to another in the poultry house by extending the parallel horizontal supports (not illustrated) of a forklift into the respective forklift openings  146   a  in the base  146 , and lifting and moving the pellet furnace heating apparatus  145  using the forklift. Moreover, the air vent housing  155  can be initially mounted at the lowermost position on the enclosure  148  when the poultry (not illustrated) are small, and gradually and progressively mounted in the higher positions on the enclosure  148  in the manner heretofore described as the poultry grow larger in size.  
     [0069] It will be appreciated from a consideration of the various embodiments of the pellet furnace heating apparatus of this invention that the pellet furnace heating apparatus can be utilized in a variety of ways for many different applications involving heating. Accordingly, while the pellet furnace heating apparatus  1  illustrated in FIGS.  1 - 8  is a typical application for homes, offices and other structures, the application can be varied in such aspects as whether or not heated air is to be vented directly into the room in which the apparatus is located or into ductwork which extends throughout the structure. Furthermore, the pellet furnace heating apparatus can be constructed in various sizes, depending upon the size of the room or area to be heated and the number of people to be warmed. Additionally, the portable embodiments of the pellet furnace heating apparatus can be moved to any desired location and can be built to any desired size for the same purpose.  
     [0070] While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications may be made in the invention and the appended claims are intended to cover all such modifications which may fill within the spirit and scope of the invention.  
     [0071] Having described my invention with the particularity set forth above, what is claimed is: