Abstract:
A media filter cabinet for a gas furnace is sized to accept a high-efficiency media filter while being easily adaptable to accept a standard size filter. A perforated duct flange on one side of the cabinet permits ease of installation since the flange can be bent at 90 or 180 degrees along the perforations, or removed, depending on the type of duct the cabinet is installed with. The cabinet is adapted to fit a standard filter by using a removable bracket and a wire to retain the standard filter within the cabinet. With the removal of a front door and a back side of the cabinet, the cabinet collapses to diminish its shipping size. In one embodiment, the cabinet is in kit form which is easily assembled.

Description:
FIELD OF THE INVENTION 
     This invention relates to the field of gas furnaces, and in particular, to a media filter cabinet used in a furnace. 
     BACKGROUND OF THE INVENTION 
     Many commercially made and custom made filter cabinets are available as accessories for hot air gas furnaces. Some furnaces come with built-in filter cabinets. Up until recently, all filters were of the standard ˜1″ wide size. With increases in filter technology, wider filters have become commercially available with filters of up to 5″ wide. Such wide high-efficiency type air filters are known as “media” filters because they use a variety of filtering media instead of just one filtering medium to filter the air passing through them. Once a filter cabinet of a particular size is installed, there is no way of reconfiguring the filter cabinet to take a different size filter. A need therefore exists for a filter cabinet which can accept or be easily modified to accept different size filters. 
     SUMMARY OF THE INVENTION 
     Briefly stated, a media filter cabinet for a gas furnace is sized to accept a high-efficiency media filter while being easily adaptable to accept a standard size filter. A perforated duct flange on one side of the cabinet permits ease of installation since the flange can be bent at 90 or 180 degrees along the perforations, or removed, depending on the type of duct the cabinet is installed with. The cabinet is adapted to fit a standard filter by using a removable bracket and a wire to retain the standard filter within the cabinet. With the removal of a front door and a back side of the cabinet, the cabinet collapses to diminish its shipping size. In one embodiment, the cabinet is in kit form which is easily assembled. 
     According to an embodiment of the invention, a media filter cabinet for a furnace includes a bottom side connected at a first end to a back side which in turn is connected to a top side; first and second front supports connecting a second end of the bottom side to the top side; a door removably connected across the two front supports; a right side connecting to the top side, the bottom side, the back side, and the first front support; a left side connecting to the top side, the bottom side, the back side, and the second front support; the right side having an opening therein defined by a perforated duct flange; the left side having an opening therein; retaining means for retaining a standard size filter in the cabinet; a width of the cabinet being sized to fit a high-efficiency media filter; and a distance between the retaining means and the left side of the cabinet being sized to fit a standard filter. 
     According to an embodiment of the invention, a media filter cabinet kit includes a front piece, the front piece including a plurality of slots and a plurality of tabs; a top piece, the top piece including a plurality of slots and a plurality of tabs, wherein the plurality of tabs of the top piece are fittable within the plurality of slots in the front piece and the plurality of tabs in the front piece are fittable within the plurality of slots in the top piece; a back piece, the back piece including a plurality of slots and a plurality of tabs, wherein the plurality of tabs of the back piece are fittable within the plurality of slots in the front piece and the plurality of tabs in the front piece are fittable within the plurality of slots in the back piece; and a bottom piece, the bottom piece including a plurality of slots and a plurality of tabs, wherein the plurality of tabs of the bottom piece are fittable within the plurality of slots in the front piece and the back piece, and the plurality of tabs in the front and back pieces are fittable within the plurality of slots in the bottom piece. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of a media filter cabinet according to an embodiment of the present invention. 
     FIG. 2 shows a perspective view of a bracket used in the embodiment of FIG.  1 . 
     FIG. 3A shows a partial sectional view of a flange configuration of the media cabinet of FIG. 1 received by an installer. 
     FIG. 3B shows a partial sectional view of a flange configuration of the media cabinet of FIG. 1 connecting to a take-off duct. 
     FIG. 3C shows a partial sectional view of a flange configuration of the media cabinet of FIG. 1 for connecting to a drop duct. 
     FIG. 4 shows a partial sectional view of a connection between the media cabinet of FIG. 1 and a flex duct used for a bottom return. 
     FIG. 5 shows a closed carton containing a kit form of an embodiment of the present invention. 
     FIG. 6 shows the carton of FIG. 5 open with the kit form of the present invention nested therein. 
     FIG. 7 shows the parts of the kit form of the present invention. 
     FIG. 8 shows an embodiment of a bracket used with the kit form of the present invention. 
     FIG. 9 shows an embodiment of a front piece of the kit form of the present invention. 
     FIG. 10A shows an interchangeable embodiment of top and bottom pieces of the kit form of the present invention. 
     FIG. 10B shows a blowup of a portion of the interchangeable embodiment of FIG.  10 A. 
     FIG. 11 shows an embodiment of a back piece of the kit form of the present invention. 
     FIG. 12 shows an embodiment of a door of the kit form of the present invention. 
     FIG. 13 shows an unassembled embodiment of the kit form of the present invention. 
     FIG. 14 shows an assembled embodiment of the kit form of the present invention. 
     FIG. 15A shows an embodiment of the front piece of the kit form of the present invention during the assembly process. 
     FIG. 15B shows an embodiment of the top (bottom) piece of the kit form of the present invention during the assembly process. 
     FIG. 15C shows an embodiment of the bottom (top) piece of the kit form of the present invention during the assembly process. 
     FIG. 16 shows an embodiment of the back piece of the kit form of the present invention during the assembly process. 
     FIG. 17 shows part of means for fastening an embodiment of a door of the kit form of the present invention to the front piece. 
     FIG. 18 shows part of the means for fastening an embodiment of the door of the kit form of the present invention to the front piece. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a filter media cabinet  10  is shaped to exactly fit to various furnace casing widths and accommodate side air return. In the drawing, cabinet  10  is shown with a rectangular shape. A right side  11  of cabinet  10  contains an opening  13  defined by a duct flange  12  which preferably contains a plurality of perforations  14  to allow ease of bending duct flange  12  during field installation. Flanges  12  can be bent at a 90 degree angle to the supply direction for connecting to take-off ducts that extend in parallel to the direction of the airflow. Flanges  12  can also be bent at a 180 degree angle to allow the flanges  12  to be used instead of special “S” clips typically used to secure drop ducts. Finally, flanges  12  can be easily removed by cutting along perforations  14  for the cases where flanges are not needed. 
     An opening  17  is defined by a left side  15  of cabinet  10 . Top and bottom portions of left side  15  preferably include a 180° folded flange  19  to aid in connecting cabinet  10  to the furnace or ductwork. Folded flange  19  also adds strength to media cabinet  10 . The air flow direction is indicated by the arrow, passing through opening  13 , the filter (not shown), and opening  17  in that order. Cabinet  10  further includes a top side  16 , a bottom side  18 , a back side  20 , and two front supports  22   a ,  22   b.  Back side  20  optionally is a separate piece and removable from cabinet  10 . A door  24  fits over the edges of front supports  22   a ,  22   b.  Cabinet  10  is hollow, thus defining a media cavity  26 . A width W of cabinet  10  is approximately 5″ so as to contain a 5″ media filter. A length L and a height H are determined so that openings  13  and  17  accommodate the air return duct. 
     A stand-off bracket  28  is removably attached to front support  22   a.  With bracket  28  removed and door  24  and back side  20  removed from cabinet  10 , cabinet  10  can be flattened along diagonally opposite seams, i.e, top right and bottom left or top left and bottom right, to present a small package for shipping. A wire  30  runs through media cavity  26  from a hole  32  in back side  20  to stand-off bracket  28 . 
     Bracket  28  is approximately 4″ long and hole  32  is an equal distance from right side  11 , so that when installed, wire  30  acts as a retaining wire for a 1″ filter. Bracket  28  and wire  30  are not installed, or uninstalled, to accommodate a 4.5″-5″ media filter. As is discussed with respect to FIG. 2 below, bracket  28  is easily removable to convert cabinet  10  to replace a 1″ filter with a 5″ media filter. Bracket  28  optionally is available in different sizes so that filter sizes between 1″ and 5″ can be accommodated. 
     Referring to FIG. 2, stand-off bracket  28  preferably includes flanges  34   a ,  34   b  which extend from a first end of stand-off bracket  28 . Flange  34   a  extends in a direction 180° away from flange  34   b , and both flanges  34   a ,  34   b  are perpendicular to a main portion of stand-off bracket  28 . Front support  22   a  preferably includes receptacles  36   a ,  36   b.  Receptacles  36   a ,  36   b  are sized and shaped so that flanges  34   a ,  34   b  of stand-off bracket  28  fit into them when stand-off bracket  28  is installed. Stand-off bracket  28  is installed by first placing the first end against front support  22   a  so that flanges  34   a ,  34   b  rest flat against the surface of front support  22   a  and then rotating stand-off bracket  28  in a direction shown by arrow  35  until flanges  34   a ,  34   b  securely engage receptacles  36   a ,  36   b.  Stand-off bracket  28  is removed by rotating in a direction shown by arrow  37 . An angled portion at a second end of stand-off bracket  28  includes a hole or slot  38  for easy field installation of wire  30  (FIG.  1 ). 
     Referring to FIGS. 3A-3C, a partial sectional view of duct flange  12  and perforations  14  is shown in FIG. 3A as filter media cabinet  10  is received by the installer. In FIG. 3B, flange  12  is bent at a 90 degree angle along perforations  14  for fastening to a take-off duct  40  via connecters such as mounting screws  42 . In FIG. 3C, flange  12  is bent back 180 degrees along perforations  14  for use with a drop duct  44 . 
     Referring to FIG. 4, an example of the ease of installation of media cabinet  10  is depicted with cabinet  10  shown as part of a horizontal furnace installation. A flex duct  46  is shown as a bottom return connected to media cabinet  10 . Flex duct  46  includes a take-off boot  48  which is attached to a hole in field supply plate  50 . Plate  50  is preferably attached to flange  12  via “S” clips  52 . 
     Referring to FIGS. 5-14, an alternate embodiment of the invention is shown. In FIGS. 5-6, a media filter cabinet  110  is shown in disassembled form packed in a carton  108 . The component pieces of media filter cabinet  110  are nested inside carton  108 . 
     Referring to FIG. 7, the arrangement of the nested pieces is shown. On one side of carton  108 , a door  124  is nested inside a top piece  116  which in turn is nested inside a bottom piece  118 . Adjacent these nested pieces on the other side of carton  108 , a front piece  122  is nested inside a back piece  120 . A bracket  128  and a small parts bag  109  are nested inside the nested combination of pieces  122 ,  120 . 
     Referring to FIG. 8, bracket  128  includes a slot  138  that receives a filter wire  30  (FIG. 1) which comes with the furnace being installed. Two outside flanges  134   a ,  134   b  are co-planar, with a center flange  134   c  in a plane offset from the plane of flanges  134   a ,  134   b.  Flanges  134   a ,  134   b ,  134   c  fit over one of the flanges on front piece  122  after cabinet  110  is assembled. Center flange  134   c  preferably has a hole  139  formed in it for affixing bracket  128  to front piece  122 . As depicted here, bracket  128  is approximately 4 inches long, so with bracket  128  installed, a 1 inch filter is retained in cabinet  110 . Without bracket  128  installed, cabinet  110  fits a 5 inch media filter. Bracket  128  is optionally made in other sizes to accommodate other sized filters. 
     Referring to FIG. 9, front piece  122  includes a duct flange  112   a,  a furnace casing flange  160 , a plurality of assembly tabs  154 , and a plurality of assembly slots  156 . The function of these elements will be explained below. 
     Referring to FIGS. 10A-10B, top piece  116  and bottom piece  118  are identical. Piece  116  ( 118 ) includes a duct flange  112   b  ( 112   c ), a furnace casing flange  160 , a plurality of assembly slots  156 , and a plurality of assembly tabs  154 . A pair of parallel filter guide rails  158  hold the largest-sized filter in place. Airflow direction arrows  162  indicate the direction of desired airflow after assembly. 
     Referring to FIG. 11, back piece  120  includes a furnace casing flange  160 , a duct flange  112   d  (FIG.  13 ), a plurality of assembly slots  156 , and a plurality of assembly tabs  154 . A pair of dimples  132  indicate a location for drilling a hole for receiving the filter wire (wire  30  shown in the previous embodiment). Airflow direction arrows  162  indicate the direction of desired airflow after assembly. 
     Referring to FIG. 12, door  124  includes a plurality of assembly tabs  154  and a screw hole  163 . 
     Referring to FIGS. 13-18, the assembly of cabinet  110  is now explained. FIG. 13 shows all the component pieces of cabinet  110 . FIG. 14 shows an assembled cabinet  110 . As shown in FIG. 15A, pre-bend tabs  154  of front piece  122  from vertical to approximately 45 degrees out. As shown in FIGS. 15B-15C, pre-bend tabs  154  of top and bottom pieces  116 ,  118  from in-line with the piece to approximately 45 degrees out. On one of the top or bottom pieces  116 ,  118 , bend the tabs  154  on one end in the opposite direction from the other end. Reverse this on the other piece. As shown in FIG. 16, pre-bend tabs  154  of back piece  120  inward to approximately 45 degrees. The pieces are now ready for assembly. 
     Referring back to FIG. 13, choose either top or bottom piece  116 ,  118  and insert its assembly tabs  154  into assembly slots  156  on front piece  122 , while simultaneously inserting assembly tab  154  of front piece  122  into the top or bottom piece  116 ,  118  chosen. Ensure that airflow direction arrows  162  of the different pieces are aligned in the same direction. Continue bending tabs  154  over from their pre-bent position until they are flattened against the mating part. Proceed likewise with the other top or bottom piece  116 ,  118 . In like fashion, attach back piece  120  to top and bottom pieces  116 ,  118 , and lock tabs  154  by bending them flat against the mating part. As shown in FIG. 17, place a fastener such as a thumbscrew  164  through hole  163  on door  124  and attach a retaining washer  166  to thumbscrew  164 . As shown in FIG. 18, place a speed nut  168  on top piece  116 . 
     Referring back to FIGS. 8 and 13, bracket  128  is attached to front piece  122  on the appropriate side. The appropriate dimple  132  is drilled out to receive wire  30  (FIG. 1) Wire  30  is cut to the right length, with the cut end preferably inserted through the drilled dimple  132 . The other end is inserted into slot  138  of bracket  128 . The 1 inch filter then fits in the space provided by the bracket-wire assembly. 
     While the present invention has been described with reference to a particular preferred embodiment and the accompanying drawings, it will be understood by those skilled in the art that the invention is not limited to the preferred embodiment and that various modifications and the like could be made thereto without departing from the scope of the invention as defined in the following claims.