Patent Publication Number: US-2007107716-A1

Title: Modular lightweight fireplace

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation-in-part of U.S. patent application Ser. No. 11/026,818, entitled “Prefabricated Modular Lightweight Fireplace,” filed Dec. 29, 2004. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention (Technical Field)  
      The present invention relates to fireplaces, particularly to a lightweight prefabricated fireplace for residential or small business installation.  
      2. Background Art  
      Fireplaces are popular features for homes and small businesses. In some locations, a fireplace may serve as a significant or supplemental source of building heat in colder climates. A fireplace may also be a centerpiece of room decor, and when in use improve the ambiance and mood of the room. In the western United States, especially the southwestern United States, a particular style of fireplace sometimes called a “kiva” fireplace has become popular. Kiva-style fireplaces are patterned after the fireplaces used by ancient and modern Native Americans (particularly the Pueblo and Hopi peoples). A kiva fireplace features gentle, rounded exterior contours and a relatively small firebox with a rounded concave interior combustion chamber. A kiva-style fireplace typically has a generally cylindrical chimney of modest diameter that is visible within the interior of the room.  
      Currently, fireplaces, particularly kiva- and Rumford-style fireplaces, ordinarily are installed during the construction of the building. They usually are constructed from relatively heavyweight materials, e.g., adobe bricks, stones, masonry, mortar, and the like. While such “original installation” kiva fireplaces are durable and handsome, their character, particularly their weight, normally requires that the building be specially designed to accommodate them. A conventional kiva fireplace generally cannot be “retrofitted” into an existing structure, especially on an upper story or floor, at least not without extensive structure remodeling.  
      A variety of fireplace types are disclosed in the following patents, which offer background in the art: U.S. Pat. No. 6,109,257 to Hodge et al.; U.S. Pat. No. 4,422,438 to Scholtz et al., U.S. Pat. No. 5,168,862 to McGee; U.S. Pat. No. 5,052,311 to Kincaid  
      A need remains for a lightweight masonry prefabricated fireplace, especially a kiva-or a contemporary Rumford-style fireplace that can be easily installed into existing structures, such as the room of a residence.  
     BRIEF SUMMARY OF THE INVENTION  
      A lightweight prefabricated masonry contemporary Rumford-style fireplace, and method of making same. The cast smoke chamber plenum section, which preferably is a plurality of interconnected modular components, stacks upon a central body to provide an easy transition from the masonry firebox to a double-walled chimney system. The apparatus may be placed in a room corner or in a chase on a flat wall. It can also be installed over wood floors, in old or new construction.  
      A primary object of the present invention is to provide a complete fireplace that can be installed with the simplicity of a zero-clearance unit and yet having the appearance of a total custom-built contemporary Rumford-style fireplace.  
      Another object of the present invention is to eliminate the undesirable cold convection that occurs with conventional masonry fireplaces.  
      A primary advantage of the present invention is that it provides a lightweight masonry firebox that can be placed in close proximity to walls containing combustible materials and can be installed over wooden floors.  
      Another advantage of the present invention is that it eliminates the need for special footings, such as those required to support the massive weight of typical all-masonry fireplaces.  
      Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
      The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:  
       FIG. 1  is a front view of a firebox component of the fireplace apparatus useable in a kiva-style embodiment of the apparatus according to the present disclosure;  
       FIG. 2  is a side sectional view of the firebox component seen in  FIG. 1 , taken along section line  2 - 2  in  FIG. 1 ;  
       FIG. 3  is a plan sectional view, from above, of the firebox component seen in  FIG. 1 , taken along section line  3 - 3  in  FIG. 1 ;  
       FIG. 4  is another plan sectional view, from above, of the firebox component seen in  FIG. 1 , taken along section line  4 - 4  in  FIG. 1 ;  
       FIG. 5  is a front, perspective, partially exploded view of the firebox component of the fireplace apparatus of the present disclosure, showing how a combustion air flume may be attached to the front of the assembled apparatus;  
       FIG. 5A  is an enlarged perspective view of the combustion air flume element of the embodiment seen in  FIG. 5 ;  
       FIG. 6  is a front perspective view of the facade frame according to the present disclosure, to approximately the same scale as  FIG. 5 , the facade frame allowing a facade to surround and enclose the firebox component seen in  FIG. 5 ;  
       FIG. 7  is a front view of a completed facade component of the apparatus, disposed around the firebox component, to provide a completed kiva fireplace generally according to the present disclosure;  
       FIGS. 8-10  illustrate various different kiva styles of facade according to the present disclosure, surrounding a firebox component of the apparatus, to provide aesthetic, lightweight fireplaces for use;  
       FIGS. 11A-11D  are perspective views of the firebox of a kiva-style embodiment of the apparatus, shown in various stages of assembly;  
       FIGS. 12A-12C  are various views of the smoke chamber plenum component of a preferred embodiment of the apparatus;  FIG. 12B  is a bottom view of the plenum component, while  FIG. 12A  is a sectional view taken along section line A-A on  FIG. 12B  and  FIG. 12C  is a sectional view taken along section line C-C on  FIG. 12B ;  
       FIG. 13  is a front perspective, partial sectional view showing a preferred embodiment of the firebox according to the present disclosure, situated within the tubular frame, with partial sections of the lath mesh and stucco applied to the hearth portion of the frame;  
       FIG. 14  is a front perspective view of the fully assembled apparatus according to the embodiment of  FIGS. 11-13 ;  
       FIG. 15  is an enlarged, partial side sectional view of the firebox aperture portion of a preferred embodiment of the apparatus, as taken generally along section line  15 - 15  in  FIG. 14 ;  
       FIG. 16  is a front left side perspective view of a desirable contemporary Rumford-style embodiment of the apparatus of the disclosure, totally assembled;  
       FIG. 17  is a back right side perspective view of the contemporary Rumford-style embodiment of the apparatus seen in  FIG. 16 , completely assembled;  
       FIG. 17A  is an enlarged sectional view of a component portion of the disclosed apparatus, showing an inner refractory layer bonded to a main layer of lightweight concrete;  
       FIG. 18  is a front left side perspective view of the two base components of the apparatus according to the embodiment of the apparatus shown in  FIGS. 16 and 17 ;  
       FIG. 19  is a front left side perspective view of the embodiment of the apparatus, showing the first right side component installed on the base of the fireplace, with base bricks installed;  
       FIG. 20  is a front left side perspective view of the embodiment of the apparatus seen in  FIG. 16 , showing the first back component installed on the base of the fireplace;  
       FIG. 21  is a front left side perspective view of this embodiment of the apparatus, showing the first left side component installed on the base of the fireplace;  
       FIG. 22  is a front left side perspective view of the embodiment of the apparatus seen in  FIG. 20 , showing the second back component installed upon the first back component;  
       FIG. 23  is a front left side perspective view of this embodiment of the apparatus showing the first front component installed on the two side components of the fireplace apparatus;  
       FIG. 24  is a front left side perspective view of the embodiment of the apparatus seen in  FIG. 22 , showing the third back component installed on the second back component of the fireplace apparatus;  
       FIG. 25  is a front left side perspective view of this embodiment of the apparatus showing the second front component installed upon the first front component of the fireplace apparatus;  
       FIG. 26  is a front left side perspective view of the embodiment of the apparatus seen in  FIG. 24 , showing the second left component installed on the first left side component of the fireplace apparatus. (The second right side component is installed in the same manner.);  
       FIG. 27  is a top view of the assembled apparatus seen in  FIG. 26 ; and  
       FIG. 28  is a right side sectional view of the apparatus shown in  FIG. 27 , taken along the section line A-A of  FIG. 27 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Currently, fireplaces are generally of two types: all-masonry fireplaces and steel “zero-clearance” fireplaces. The present disclosure offers the homeowner or homebuilder a lightweight alternative fireplace that may be installed in a wide variety of locations, including the upper floors of existing buildings of two or more stories. While the disclosed method and apparatus have utility in new construction, it is contemplated that an advantage of the method and apparatus are their suitability for practice in existing buildings. Thus, the inventive fireplace may be used in either original or “retrofit” installation.  
      The apparatus is a wood burning fireplace that can be converted, if desired, to gas burning (with ceramic logs), without requiring any basic design change. In its preferred embodiment, the inventive apparatus provides the user with an aesthetic southwestern style kiva fireplace, or a contemporary Rumford-style fireplace, both of which provide a supplementary heat source.  
      The fireplace according to the disclosure is advantageous over the known art in several respects. It is much lighter than the masonry fireplaces of conventional construction, and requires no special footings. It eliminates cold convection that occurs with solid masonry fireplaces. It can be installed over wood floors in new or existing homes. In contrast with known “zero-clearance” fireplaces, the present kiva-style apparatus features a semi-circular firebrick (or lightweight concrete) firebox interior with a lightweight stuccoed tubular steel and mesh frame. The frame of the inventive fireplace permits the unit to have the shape of a traditional kiva fireplace, including an arched firebox opening. In sum, the user can appreciate the aesthetics of a real southwestern kiva fireplace without the disadvantages of an all masonry fireplace or steel zero-clearance fireplace. The Rumford-style version of the apparatus offers the same advantages, but ordinarily features a rectilinear firebox having flat refractory panels, and does not require the tubular-framed outer facade.  
      The disclosure is of a lightweight masonry fireplace that may burn either solid fuel, particularly wood, or fluid fuel, such as natural gas or propane. The firebox of the apparatus may be placed in direct contact or close proximity to combustible building materials, and accordingly may be placed against or close to building walls. The firebox disclosed herein can be used in either new construction or remodeling and in close proximity to the structure&#39;s walls. The firebox is zero-clearance in basic type, while the fireplace unit features a double-walled, air-cooled metal chimney system. As mentioned, no special footings are required, so the apparatus may be installed over wood floors.  
      The firebox of the kiva-style embodiment of the present disclosure is fashioned from refractory firebrick inside the combustion chamber, which in turn is partially surrounded by an outer shell of lightweight concrete. The apparatus&#39; lightweight facade, which houses the firebox, achieves the appearance of a custom adobe fireplace.  
      Attention is invited to the drawing figures, especially  FIGS. 1-6 , which illustrate and disclose aspects of the present method and apparatus. In the kiva-style embodiment of these figures, the apparatus includes two major components, the firebox  20  ( FIGS. 1-5 ) and the facade  50  ( FIGS. 6 and 7 ). These elements are manufactured mostly off-site, and largely by pre-casting in vermiculite concrete, and as modular components are transported from the manufacturing facility to the residential or small business job site for installation. The firebox  20  is assembled and secured in place within the structure (e.g. preferably in the corner of a room), and then is covered and surrounded by the facade  50 . When the inventive fireplace is completely and properly assembled, the facade  50  substantially surrounds and covers the firebox  20 , there being however a volume of air space between the facade and the exterior of the firebox.  
       FIGS. 1-4  illustrate one embodiment of a firebox  20  according to the disclosure. The embodiment of  FIGS. 1-4  is suitable for many applications, but more preferable embodiments thereof will be disclosed hereinafter.  FIGS. 1-4 , however, serve to illustrate generally the configuration of fireboxes according to the kiva-style embodiment. It is seen that the firebox  20  features three main sub-components: a base  22 , a pre-cast vermiculite concrete central body  24 , and a smoke plenum section  26 . The base  22 , which has a generally semicircular convex exterior back, is placed upon the floor, or upon concrete or “cinder” blocks over a wood floor, of the room in which the fireplace is to be installed. The central body  24  has a concave interior chamber therein and a convex back, as suggested in  FIG. 4 , and is disposable upon the base  22  before the firebox  20  is useable. The central body  24  has an inner body wall  27  defining and partially surrounding a combustion chamber  28 ; the combustion chamber is the location of the fire when the completed apparatus is in use. The inner body wall  27  also at least partially defines a firebox aperture  29  opening into the combustion chamber  28 . The combustion chamber is lined with split refractory fire brick or a One-inch thick cast refractory lining. As best seen in  FIGS. 1, 3 , and  5 , the inner body wall  27  preferably has a substantially arcuate plan profile. A plurality of lightweight split refractory bricks  34  are cast into the inner body wall  27 . As indicated by  FIGS. 1-3 , the central body  24  and the smoke plenum section  26  have a thick (e.g. 4 inches) outer shell  47  of lightweight vermiculate concrete, preferably reinforced with No. 16 gage 2-inch by 2-inch square grid welded wire screen  49 .  
      The smoke plenum section  26  is disposable upon the central body  24  when the firebox is in use to contain a flame in the combustion chamber  28 . The upper plenum section  26  also has an inner plenum wall  31  confronting and defining the upper bounds of the combustion chamber  28 . As seen in  FIGS. 1 and 2 , the inner plenum wall  31  at least partially defines an upper portion  45  of the box aperture  29 . This upper portion  45  in a kiva style fireplace may be a metal arch, for example, to define the arched firebox opening characteristic of kiva fireplaces ( FIG. 7 ).  
      The facade  50  of the kiva-style embodiment is locatable around the firebox  20  to at least partially surround and enclose the firebox. The facade  50  preferably has a frame  51  crafted from lightweight steel tubes that have been bent and joined to outline the exterior contours of a typical kiva style fireplace, as best seen in  FIG. 6 . The frame  51  defines a facade aperture  52  as well as the chimney enclosure  54 . An advantage of the kiva version of the apparatus is the use of bendable tubing to craft the frame  51 , thereby permitting a fireplace facade exhibiting the smooth, graceful curves and rounded contours customarily associated with kiva style fireplaces.  
      Because the base  22 , central body  24 , and plenum section  26  are modular, they can be separately manufactured and transported to the job site, and there stacked one upon the other to assemble the firebox  20  as illustrated in  FIGS. 1, 2 , and  5 . The central body  24  is connectable to the base  22 , and the smoke plenum section  26  is connectable to the central body  24 , using refractory mortar  36 , so that the three main subcomponents of the firebox  20  are securely mortared together in the completed apparatus for use. The assembled firebox  20  is situated so that the central body  24  and plenum section  26  are at least about three inches from the nearest adjacent combustible building materials (e.g. walls). The facade frame  51  may then be placed over the installed firebox  20 . The facade aperture  52  has a size and shape generally corresponding to the box aperture  29 ; these two apertures are alignable to permit access through the facade  50  into the combustion chamber  28  in the completed fireplace assembly, as seen in  FIG. 7 . With the facade aperture  51  and the box aperture  29  in registration, the edges of the apertures are in close adjacency, and can be sealed with mortar, to provide an integral aperture and to prevent smoke and debris from entering between the firebox and facade. The juncture of the front of the firebox  20  with the front of the facade  50 , where the edges of their respective apertures come together, is the only area of substantial contact between the firebox and the facade. The firebox is within, but spaced-apart from, the facade  50 .  
      To provide a fire-resistant and yet lightweight fireplace, the base  22  preferably is pre-cast of vermiculite concrete. As seen in  FIGS. 1 and 3 , for example, the base  22  preferably is generally planar, having sides and a back defined by a single wall  32  defining a substantially arcuate plan profile. Similarly, the central body  24  has an outer shell  47  pre-cast or otherwise formed of vermiculite concrete.  
      A steel anchor plate damper assembly  40  is shown in  FIGS. 1 and 5 . The damper assembly  40  is secured (for example with ⅜-inch×3 inch lag bolts) over a chimney aperture in the top of the smoke plenum section  26  of the firebox. The interior of the damper  41  receives the inner stainless steel chimney  43  of an air cooled steel chimney system  42 , thus providing masonry-to-steel chimney connection. The damper  41  is positive open or closed. This is accomplished by a steel bar counter-weight  56 . When the damper handle  57  is pushed up, the counter-weight  56  holds the damper plate  58  open. When the damper handle  57  is pushed down, the damper plate  58  closes.  
      Referring again to  FIG. 6 , it is seen that a fireplace facade frame  51  is crafted from tubular steel, for example ½-inch tubes, bent, welded and assembled to achieve the appearance of a southwestern kiva fireplace. A steel diamond mesh lath  60  is attached, as by metal screws, to the frame  51  generally to define the exterior contours of the facade  50 . At least one, preferably three or more, coats of fiberglass-impregnated stucco  62  is applied to the entire facade  50 , with the result that the fireplace obtains the appearance seen in  FIG. 7 . The frame  51  can be secured to the adjacent interior walls of the building to supply overall stability for the apparatus, a preferred and traditional location of a kiva fireplace being the corner of a room.  FIG. 7  depicts the appearance of the completed apparatus, the facade  50  having been secured (e.g. by adhesives and/or screws) in place around the firebox  20  and the chimney system  42 . A pleasant transition finish preferably is applied to aesthetically join the edges of the facade  50  to the adjacent walls.  
      The facade  50  is completely factory manufactured. The facade  50 , with frame  51 , is transported to the installation site, and is secured to the firebox and to the site structure (e.g. walls), and then added stucco  62  is applied.  
       FIGS. 8, 9  and  10  illustrate additional alternative fireplace designs according to the kiva embodiment of the apparatus. It will be readily appreciated by one of ordinary skill in the art that the flexibility in design provided by the use of the facade frame  51  permits the inventive apparatus to have a facade  50  manifesting any of a wide variety of custom exterior appearances. All aesthetic designs may be manufactured according to the foregoing disclosure.  
      Referring particularly to  FIGS. 5 and 5 A, the inventive fireplace optionally but preferably includes a combustible air flume  35 , attached to the base  22  proximate to the box aperture  29  when the fireplace is completely assembled and the firebox  20  is in use. The flume  35  draws air toward the combustion chamber  28 , as further described herein. The flume  35  essentially is a vented conduit, and preferably features some means for closing a vent hole in the conduit when the fireplace apparatus is not in use.  
      The combustion air flume  35  is mounted to the face of the base  22 , halfway below the box aperture  29 . This mounting can be accomplished by, for example, angle brackets  64  and #8×2½ inch screws. The flume  35  is mounted so as to position a vent  37  towards the combustion chamber  28 . A hinged vent door  38  is provided upon the flume  35  as a means to controllably open and close the vents  37 , the vent apertures preferably being closed when the fireplace is not in use. A handle  63  is mounted upon the vent door  38  for ease and safety of manipulating the door  38 . As seen in  FIG. 5A , when the vent door  38  is opened, it exposes and uncovers at least one vent aperture, e.g., a pair of vents  37  in the form of two ¾-inch by 15-inch slots in the flume  35 ; the flume  35  preferably is a conduit crafted from, for example, a length of 2-inch by 2-inch (or 4-inch by 4-inch) square steel tube with open ends. The door  38  can be a length of right-angle-iron mounted with hinges upon the flume  35 . The hinges permit the door to pivot between an open and a closed position; to open, the handle  63  is pushed toward the fireplace (directional arrow in  FIG. 5 ).  FIG. 5A  shows the flume  35  in an open position; to close, the user can simply pull on the handle  63  to pivot the door  38  forward (directional arrow in  FIG. 5A ) to rotate the vent door into a position covering the vents  37 . A plaster stop and door channel  65  is mounted on the face of the flume  35 , and provides a finished edge at the fireplace opening and a slot for screen or glass doors.  
      In use, the flume  35  draws air in through its open ends, and delivers the air to the combustion chamber  28  of the firebox  20 . An approximately 6-inch diameter vent (not shown) is required in an outside wall of the associated building structure to provide outside air within the interior frame cavity defined by the facade frame  51 . Such outside air also provides cooling for the double-walled chimney system  42 .  
      A door frame and glass and/or screen door (not shown) may be provided in and for the facade aperture  52  generally according to convention, to prevent embers from popping from the chamber onto the building floor.  
      From the foregoing, it is also evident that the invention includes a method of assembling a lightweight modular fireplace. The method includes the initial step of assembling the firebox  20  by pre-casting the base  22  of vermiculite concrete, and pre-casting the central body  24  of vermiculite concrete. Then, the method includes stacking the central body  24  upon the base  22  and connecting the central body to the base, the firebox  20  partially surrounding the combustion chamber  28 , and also stacking the smoke plenum section  26  upon the central body  24  and connecting the plenum section to the central body. Other steps of the method are fashioning the facade frame  51  from tubular steel, locating the facade frame  51  around the firebox  20 , thereby at least partially surrounding and enclosing the firebox  20 , and covering the facade frame with stucco, as described above.  
      The preferred embodiment of the kiva firebox of the apparatus may now be described, with the foregoing description of an acceptable alternative firebox embodiment serving as reference and background. All versions of the firebox component described herein are useable with the facade component  50  as described. A preferable firebox offers advantages of simpler construction and improved safety vis-à-vis the alternative firebox disclosed previously. The preferred embodiment features modular construction, but the base, central body, and smoke plenum section are differently configured. The general concept of the disclosure as described above remains the same, and the construction materials are unchanged. A separately devised front portion, defining the firebox aperture, is provided. Thus, the description of the alternative embodiment of the firebox above applies as well to this preferred embodiment, with the exception of the differences specifically noted and described below.  
       FIGS. 11A-11D  show the base  122 , central body  124 , front  200  and smoke plenum section  126  that are assembled to comprise the firebox  120  of one preferred embodiment. FIGS.  11 A-D offer a generally progressive depiction of the firebox  120  ( FIG. 11D ) at serial stages of assembly. The base  122  is planar, and is provided with centrally disposed refractory bricks, as seen in  FIG. 11A . The base  122  is placed upon a suitable base or pedestal, such as cinder blocks or the like.  
       FIG. 11B  shows the situation of the central body  124  upon the base  122 . The central body  124  is markedly distinct in its overall shape from the central body of the previously disclosed alternative embodiment. As seen in  FIG. 11B , the central body  124  is generally semi-cylindrical in shape; the cast vermiculate concrete wall defines coaxial semi- or hemi-cylindrical interior and surfaces. The precise overall shape of the central body  124 , in the horizontal section, may actually be a modified or stylized paraboloid, providing for added front-to-back depth of the combustion chamber  128 , but characterizing the central body as hemi-cylindrical fosters basic description of the apparatus. The wall of the central body  124  may have approximately the same thickness (e.g., 4-5 inches) as in the alternative embodiment. The interior surface of the central body  124 , which defines the space of the combustion chamber  128 , is covered with the split refractory bricks in generally the same manner as previously described. Notably, the interior firewall of the central body extends upward all the way to the plenum section  126 , and is lined with refractory brick throughout its height. The transition surfaces  130 - 135  (described further below) of the interior of the smoke chamber plenum  126  are arranged so to intercept and direct hot gases and smoke rising from anywhere within the combustion chamber  128  interior to the central body  124 .  
      Referring to  FIG. 11B , it is seen that the arcuate exterior dimension of the exterior of the central body  124  corresponds generally with the dimension of the arcuate exterior of the base  122  so that the exteriors of the base  122  and body  124  are in flush registration (i.e., define the same imaginary curve) when the central body is paced on the base. Further, it is seen that the forward ends  81 ,  81 ′ of the central body  124  are aligned to be in coplanar registration with the forward end  83  of the base  122 .  
      This embodiment has a separate front  200  section for the firebox. The front  200  has a generally planar vertical exterior surface and a generally planar interior vertical surface, these surfaces being about parallel and thus defining a front wall of approximately 4-5 inches thickness. The front  200  defines therein the arched firebox aperture  129 . The front has a flat top, and is equal in height to the height of the central body  124 . Accordingly, when the front  200  is secured in place, its flat top is coplanar with the flat top of the arcuate wall of the central body  124 , as seen in  FIG. 11C . Also as best seen in  FIG. 11C , during assembly the interior vertical surface of the front  200  is placed and secured flush against the forward ends  81 ,  81 ′ of the central body  124 . Therefore, the front  200  when secured to the central body  124  actually “overhangs” or protrudes forward from the forward end  83  of the base  122  a distance corresponding approximately to the thickness of the front  200 . The space defined below the front  200  and in front of the forward end  83  of the base  122  is sized to receive an air flume (e.g.  35  in  FIGS. 5A, 15 ), which is attached to the base  122 . When a preferred embodiment is fully assembled, therefore, the flume  35  fits snugly between the supporting pedestal and the bottom surface of the front  200  Similarly, the front-to-back dimension of the flume  35  preferably is about equal to the wall thickness of the front  200 , so that in the assembled firebox  120 , the front surface of the flume  35  is in coplanar registration with the front or exterior vertical surface of the front  200 .  
      In this embodiment, the smoke plenum section comprises a single pre-cast component defining a substantially planar top and a central chimney aperture. The transition surfaces, for directing combustion smoke and vapors to converge upward toward the chimney, are defined on the bottom of a single pre-cast component, arrayed around a central chimney aperture.  
      The smoke plenum section  126  is placed upon and secured to the top surfaces of the central body  124  and front  200 , as seen in  FIG. 11D . The smoke plenum section  126  has a flat bottom surface for flush contact and juncture with the flat tops of the front  200  and central body  124 . It also features a generally planar, flat top, as seen in  FIG. 11D . Also, as is evident from  FIG. 11D , the arcuate dimension of the curved back wall of the plenum section  126  is contoured to correspond to the radius or definition of curvature of the exterior surface of the central body  124 , so that the exteriors of the plenum section  126  and central body define generally the same curvature to be in aesthetic alignment. The forward surface  85  of the plenum section  126  is coplanar with the forward or exterior surface of the front  200  when the components are assembled, as seen in  FIG. 11D .  
      Added detail of the smoke plenum section  126  is provided in  FIGS. 12A-12C .  FIG. 12B  is a bottom view of the plenum section  126 , that is, its appearance as if viewed by an observer looking upward from within the combustion space  128 .  FIG. 12A  is a sectional view taken in a lateral plane (i.e., a vertical section from side-to-side, section A-A in  FIG. 12B ) of the plenum section  126 , while  FIG. 12C  is a sectional view in a vertical place disposed front-to-back (section C-C in  FIG. 12B ).  FIGS. 12A-12C  illustrate that the body of the plenum section  126  has a central chimney aperture  87  defined there through, via which smoke exits the combustion chamber  128  for exhaustion via an air-cooled steel chimney system, generally as previously described herein. Significantly, the smoke chamber plenum  126  does not define any part of the arched firebox aperture  129 .  
      The plenum section  126  preferably is cast from lightweight vermiculite concrete, and is cast with interior transition surfaces  130 - 135 . The transition surfaces  130 ,  131 ,  132 ,  133 ,  134 ,  135  are inclined from vertical and canted in an upwardly convergent array, as illustrated especially in  FIGS. 12A and 12C , to direct rising smoke and vapors from the entire volume of the combustion chamber  128  to the relatively narrower chimney aperture  87 . The chimney aperture  87  is fit with and covered in part with an anchor plate damper assembly ( 40  in  FIGS. 1 and 5 ). Thus, the interior of the plenum section  126  effectively defines a smoke funnel for gathering combustion by-products for directional flow to the chimney system.  
      Attention is invited to  FIGS. 13 and 15 . It is seen that the box aperture  129  in the front  200 , as lined by the box aperture wall  171 , can be closely tailored in size and shape to closely register with the size and shape of the corresponding aperture in the steel tube frame  51 . The correspondence in the respective combustion chamber openings (firebox and frame) in this preferred embodiment is improved in comparison to the previously described alternative embodiment, and permits the wire mesh lath overlay  60  to be wrapped around the corner tube defining the edge of the frame&#39;s firebox opening and folded directly into contact with the arched box aperture wall  171  of the front  200 . By closely matching the firebox openings in frame  51  and front  200 , the possibility of dangerous flames or hot gasses improperly venting between the front of the firebox  120  and the frame  51 , and entering the void defined inside the frame, is prevented. When the entire frame  51  is covered with mesh lathe and then stuccoed and plastered, as previously described, the completed apparatus has the pleasant aesthetic appearance seen in  FIG. 14 .  
      Reference to  FIG. 15  provides added description of the improved safety feature of the disclosed apparatus.  FIG. 15  is an enlarged, partial, side section view of the aperture portions of the apparatus, taken generally along section line  15 - 15  on  FIG. 14 . The firebox  120  is situated in the interior space confined in the facade defined by the tubular frame  51 . There is a small gap or space  90  between the tubular frame  51  and the components constituting the firebox  120 , particularly between the frame and the exterior of the front  200 . The screen lath  60  is securely attached to the outside of the frame  51  to define the contours of the exterior facade, as previously described. This preferred embodiment of the apparatus prevents flames and hot gases from exiting the combustion chamber  128  and entering the space  90  between the exterior of the firebox  120  and the interior of the lath-covered frame  51 . This prevention is provided by the expedient of cutting the screen lathe  60  in a manner to permit it to be folded into the firebox aperture  129  and secured directly to the box aperture wall  171 , as with screws or the like. The folded lath  60  thus defines an arched “tunnel” between the frame&#39;s aperture and the firebox aperture  129 . The lathe  60  is coated with refractory cement (not shown in  FIG. 15 ) through the interior extent of the arch, to isolate the interior of the aperture tunnel from the space  90  between the outside of the firebox  120 .  
      This preferred embodiment offers two significant advantages over the previously described alternative embodiment. The most important advance is in safety. This preferred embodiment also is simpler and less expensive to assemble.  
      In the afore-described alternative embodiment, it was determined that there is a possibility for inadequate functional closure between the lath-covered frame and the exterior of the firebox in the vicinity of the firebox aperture  29 . Due to the fact that in the former, alternative embodiment, the firebox aperture  29  was not as closely aligned with, and was separated a substantial horizontal distance from, the corresponding aperture in the frame  51 , it is thus easier to mistakenly make a faulty installation with that embodiment. Sealing the gap or space (analogous to the narrow gap  90  in  FIG. 15 ) is more problematic. Modestly sized pieces of screen mesh  60  sometimes have to be specially cut and sized for fitting between the frame and firebox, and interiorly covered with high-temp refractory mortar. This task must be performed with care, to avoid the leaving of an open gap whereby flames or hot gas can rise upward out of the combustion chamber  28  and into the void between the firebox and frame  51 . Installers sometimes inadvertently close the gap with ordinary plaster or stucco which is unable to withstand exposure to the temperature extremes of the vicinity. In extreme, and hazardous, cases, the plaster or stucco bakes, cracks, and falls away, leaving an open passage for the escape of hot gas or even flames from within the firebox to the space inside the frame and facade. In this embodiment, the frame  51  is part of the interior of the firebox.  
      In this preferred embodiment, and as shown in  FIG. 15 , the gap between frame  51  and the outside of the firebox  120  is much more readily and easily closed and sealed, by the mesh  60  being attached directly to the box aperture wall  171 . The configuration and location of the front  200  results in the box aperture  129  being situated much closer to, and better aligned with, the aperture in the frame  51 , so that the gap  90  is rapidly closed with mesh lath  60  covered with an refractory cement lining.  
      This preferred embodiment also is much simpler and cost effective to manufacture. In the alternative embodiment, both the plenum section  26  and the central body  24  have a number of geometrically complicated surfaces. The plenum section  26 , in particular, has a number of compound angles and complex surface relationships in its inner plenum wall  31 , complicating its construction and lining. (The smoke chamber plenum  26  of the alternative embodiment may have to be cast in several pieces and then assembled.) Further as seen in  FIG. 1 , for example, the plenum  26  also defines the upper portion of the arched combustion chamber aperture  29 . The firebox aperture  29  thus is defined by both the central body  24  and the smoke chamber plenum  26 , requiring careful assembly to proved a safe and aesthetic registration between the two components.  
      In marked contrast, in the embodiment of  FIGS. 11-15 , the smoke chamber plenum  126  can be cast as a single piece. After the master mold is originated, the interrelationships and locational dispositions of the transition surfaces  130 - 135  are fixed, and easily and repeatedly reproduced by expediently pouring multiples of the vermiculite concrete in the plenum mold.  
      Also, the provision of a separate front  200  as described simplifies the definition of the firebox aperture  129 . The arched aperture is cast in the one-piece front section  200 , so that the aperture is uniform, the arched front  200  is structurally sound, and the firebox aperture is defined by one component instead of two. Assembly of the complete firebox is more simply and elegantly accomplished, resulting in a faster installation and a confined firebox.  
      Attention is invited to  FIGS. 16-26  which depict another preferable embodiment according to this disclosure. This contemporary Rumford-style embodiment is similar in some respects to the kiva-style embodiment of  FIGS. 11-13 , but offers the advantage of having a firebox with no arcuate or curved castings; also, no exterior tube-framed facade is required.  
      Traditional “Rumford” style fireplaces are tall and shallow to increase heat reflection, and have streamlined throats to eliminate turbulence and carry away the smoke with comparatively little loss of heated room air. The firebox, particularly, is made smaller and shallower than many other styles of fireplace, and with widely angled covings to radiate better. But Rumford fireplaces conventionally are assembled from heavy brick and mortar, and thus require substantial foundational support.  
      The Rumford-style embodiment of this disclosure is assembled from modular components that have rectilinear edges and planar surfaces; the central body, in particular, comprises a plurality of interconnected substantially planar components, as does the smoke plenum section. The molds for this firebox  220  are thus simpler to make and use, and many users may find assembly easier as well. The firebox of  FIGS. 16-26  is useable in combination with the façade  50  component as previously described, if desired, including the advantages discussed in conjunction with  FIG. 15 . However, a Rumford fireplace according to the present disclosure typically will not employ a separately framed and stuccoed façade; rather, its firebox and smoke plenum portions are assembled to present an attractive fireplace without a separately framed cover.  
      The Rumford embodiment of the apparatus and method includes eleven modular components. The inside of the fireplace  220  is has a one-inch lining of rust-colored refractory cement, cast in a herringbone pattern (or other desired decorative display), and backed up with lightweight vermiculite concrete.  
      As mentioned, the component pieces or sections of the apparatus are cast from cementitious materials at the factory. Casting is done into forms, where the sections are allowed to cure. The pouring is accomplished in two steps. First, refractory cement is poured to a preselected depth into the bottom of the mold. Then, a layer of lightweight vermiculite concrete is poured on the first layer of refractory cement, and the two layers are permitted to cure together to prevent the formation of a “cold joint” between layers.  
      Attention is invited to  FIG. 17A , further illustrating this aspect of the method and apparatus.  FIG. 17A  is a sectional view (possibly either vertical or horizontal section) of a firebox component of the apparatus. Each component or section of the firebox, particularly sections D, E, F, and H (as described further below) has a first refractory layer  400  that defines the inner face of the component, that is, the surface of the component exposed to the fire. The first refractory layer  400  is poured first into the component mold, and is comprised of a cementitious mix that, when cured, withstands the high temperatures of the fire but without significant heat degradation, generally in accordance with known methods of preparing refractory cements.  
      This refractory layer  400  also defines the interior surface of the firebox that is viewable through the fireplace aperture. Accordingly, the component mold is provided with grid or network of raised, rounded, ridges which define depressed faux mortar joints  412  in the inner face of the component ( FIG. 17A ). The channels defining the faux joints  412  thus are cast integrally into and with the refractory layer  400 . The pattern of the mold configuration provides the joints  412  with the appearance of a joint between an array (e.g., herringbone) of bricks, so that the cast refractory layer  400  has the appearance of stacked bricks. This decorative aesthetic may be enhanced by providing the refractory layer  400  with a reddish or brownish hue evocative of, or mimicking, the color of real brick.  
      Soon or immediately after the refractory layer  400  has been poured into the mold, but before the refractory layer has cured, the main layer  410  of vermiculite concrete is poured to fill the mold to its design capacity. Both layers  400  and  410  are cured together. Optionally, mechanical cleats or other fastening means (not shown) may be disposed into both layers  400 ,  410  across their common interface, to promote juncture of the layers and the structural integrity of the section or component. After the requisite amount of curing time, the cast component comprising the two layers bonded together is removed from the mold. The complete component or section may be further finished (i.e., by trimming and sanding) and prepared for installation. After removing the cast section from the mold, a thin layer of darker-colored (e.g., grey) mortar, or some other permanent coloring medium, may be disposed into the faux joints  412  to give the refractory layer  412  the appearance of genuine stacked and mortared brick.  
      This practice of molding directly and integrally into the components D, E, F, and H the pattern of stacked brick presents the advantage of an authentic-looking Rumford fireplace without the disadvantage of after-affixed ornamental bricks (refractory or otherwise). Separate ornamental bricks mortared to the interior of a vermiculite concrete firebox, in a subsequent step after the concrete firebox components have cured, tend to detach and fall from firebox after a comparatively short period of fireplace use. The disparate indices of thermal expansion and contraction, between the after-attached bricks and the structural block components, causes the bricks to loosen and fall away after few cycles of fireplace heating and cooling. In the present apparatus, the faux bricks are durable for most of the fireplace&#39;s functional lifetime.  
       FIG. 18  illustrates the base of the fireplace comprised of two (right and left) base sections A and B. The base sections A, B are keyed to fit together along the centerline of the fireplace  220 . Refractory mortar is applied along the centerline key joint and the base sections set in place, as indicated in  FIG. 18 , to define a base with a roughly trapezoidal footprint. The assembled base preferably features an elevated rim on three sides, as shown in  FIG. 18 , to define a recessed area for containing a layer of refractory bricks for lining the combustion chamber floor. A thin coat of refractory mortar is then applied over the recessed base area, and split firebrick C is set in place, as shown by  FIG. 19 .  
      A thin layer of refractory mortar is then applied on top of the concrete rim portion of the base. Referring to  FIG. 19 , a first right side component D is aligned with and situated on the corresponding outside edge of the base A, B. Referring to  FIG. 20 , refractory mortar also is applied to the vertical sides of the first back component E, which then is aligned with the back edge of the base and with the rear corner of the first right side component D and set in place.  
      Turning to  FIG. 21 , it is seen that refractory mortar is then applied to the joining edges of the first left side component F, which is then aligned with the corresponding side edge of the base, and lag bolted to the first back component E. The first right side component D likewise is lag bolted to the first back component E. The first side components D, F generally define irregular pentagons in overall shape, while the first back component is shaped generally as a rectangle. As best seen in  FIGS. 19 and 22 , the first side portions D, F have small horizontal ledges defined at their front top corners, but the principal lengths of the upper edges of the sides D, F preferably are inclined somewhat, rising from front to back as seen in  FIGS. 20-22 .  
      The trapezoidal second back component H is ready to be set in place. Refractory mortar is applied on exposed joining edges of both first side components D, F, as well as along the exposed top edge of the first back component E.  FIG. 22  shows that the second back component H is lowered (shorter bottom edge down) onto the correspondingly-sized and shaped space between the first side components D, F, and set in place upon the first back component E. This second, or upper, back component is secured to the side components D, F with lag bolts.  
      Reference is made to  FIG. 23 . Refractory mortar then is applied to upper surface of the dropped-down ledge at the top front corner of each of the side components D, F. The first front component I is set into place upon the front ledges of the side components, in alignment with the front of the fireplace previously defined by the base and the first side components. Refractory mortar then is applied along the top of the second back component H, and a third back component J is set in place thereon, as seen in  FIG. 24 . The third back component can be situated at a desired forward-leaning angle, but in the preferred embodiment is oriented substantially vertically. Referring to  FIG. 25 , refractory mortar is applied to the top of the first front component I, and a second front component K of generally trapezoidal shape is aligned with the side components D, F and disposed upon the first front component I. As best seen in  FIGS. 27 and 28 , second front component K is preferably is disposed at an angle upon the first front component; the pitch or inclination of the second front component K defines an angle of between about 20 and 30 degrees from the vertical, most preferably approximately 26 degrees from the vertical. Third back component J is situated approximately vertically.  
      As seen in  FIG. 26 , the final two side components L are then installed. Refractory mortar is applied to the exposed top edges of the first side components D, F and to the exposed edges of the components I, J, and K at their juncture with the second side components L. The second side components L (only one seen in  FIG. 26 ) are then set in place. As indicated by combined reference to  FIGS. 24-26 , the second, or upper, side components L rest primarily upon the top surfaces of the respective left and right first side components D, F, but also rest upon the side surfaces of the third, uppermost, back portion J, as well as upon rearward-extending top surfaces or ledges of on the back of the first front component I. The second side sections L are lag-bolted to the upper second back component H.  
      As seen in  FIGS. 24-26 , and as suggested in  FIG. 17 , the two final side components L may be inclined inwardly at suitable angles from vertical, and may have oblique bottom surfaces to accommodate their inclinations; (the third back component J is disposed upon and secured to the second back component H, while the final side components L are disposed upon and connected to respective ones of the first side components D, F). These components I, K lean inwardly toward the center of the combustion chamber, so to create a funnel-like section of decreasing size (proceeding upward), thereby defining a plenum section which collects and directs smoke to the narrower chimney.  
      It is seen therefore that the first and second front components I, K, the two second side components L, and the second and third back components H, J define the smoke chamber plenum for guiding smoke from the combustion chamber to the flue and chimney. The combustion chamber is largely enclosed by the first side components D, F, the first back component E, and the first front component I, as well as the base A, B.  
      When thus assembled, this version of the firebox  220  appears as seen in  FIGS. 16 and 17 . It is seen that this firebox of the apparatus and method uses solely planar components, and avoids the use of components pre-molded in more complicated arcuate shapes, as seen in  FIGS. 11A and 11B .  
      An advantageous feature of the apparatus and method is illustrated by  FIGS. 27 and 28 .  FIG. 27  is a top view of the Rumford embodiment of the apparatus assembled according to the present method.  FIG. 28  is a right-side sectional view of the assembled apparatus. This version of the Rumford style fireplace has, as seen in  FIG. 28 , its second front component K inclined from the vertical so to “lean” from the front toward the back of the fireplace, as previously described, toward the vertically disposed third back component J. By this design, the entire fireplace apparatus can be situated proximate to the wall of the room in which the fireplace is located, and directly below the vertically oriented chimney assembly  414  ( FIG. 28 ). The smoke plenum portion of the fireplace thus readily aligns vertically with the chimney assembly  414 , which typically according to this disclosure is assembled from cylindrical metal ductworks. In Class A chimneys especially, elbow elements for such ductwork are relatively expensive. By employing a tilted second front component K, the fireplace can be assembled below the chimney  414  while eliminating the need for any expensive chimney elbows or doglegs to register the opening  416  in fireplace&#39;s smoke chamber with the bottom of the chimney duct.  
      Although an apparatus and method have been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present disclosure will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all patents and publications, cited above are hereby incorporated by reference.