Abstract:
A transition fitting interconnects a furnace combustion air chamber to an air duct supplying combustion air to the furnace. The fitting includes a housing portion having opposed first opening and second openings, the first opening being disposed adjacent a furnace combustion air chamber upon installation and three tubular portions connected to the housing portion and disposed adjacent to the second opening. Each of the three tubular portions define a central axis and have a first opening into the housing portion and a second opening configured to receive an inlet air duct. One tubular portion is disposed at an angle to the central axes of the other two tubular portions. A peripheral flange portion sealably attaches the housing portion to a frame portion of a furnace. A removably attachable cap is configured to selectively close a tubular portion not connected to an external air duct.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention is directed to a three-way fitting for interconnecting the burner chamber of a furnace to an inlet air supply duct.  
       BACKGROUND OF THE INVENTION  
       [0002]     Typically, gas furnaces for use in residential dwellings are designed to be installed in more than one configuration. The furnace unit may be installed for vertical airflow i.e., up or down, or for horizontal airflow, i.e., left or right, through the furnace. The units may be free-standing vertically or placed horizontally on their side. All furnaces require a source of supply or inlet air for fuel combustion. Gas furnaces include a chamber which houses the gas burners, in which inlet air mixes with the natural gas and is ignited to produce a source of heat. In a new furnace before installation, the burner chamber is equipped with an opening for interconnection to an air inlet duct in a building. Generally, this opening is equipped with only a flange about the periphery for connecting the duct to the burner chamber of the furnace. However, in many instances, it is the case that the air inlet duct is not disposed adjacent to or in line with the burner chamber. When that occurs, the furnace installer must adapt the air inlet duct to the burner chamber flange by use of various elbows and customized duct fittings. Often it is required of the furnace installer to fabricate the duct fittings in the field out of sheet metal parts or tubular pieces. Custom fittings and fabrication of duct fittings in the field require additional installation time, and special material and tools, all of which adds cost and inconvenience to the furnace installation.  
         [0003]     Therefore, there is a need for a furnace inlet air transition to a burner chamber that provides an easy connection to the outside air duct regardless of the location of the outside air duct.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention is directed to a transition fitting for interconnecting a furnace combustion air chamber to an air duct supplying combustion air to the furnace. The fitting includes a housing portion having a first opening and a second opening opposite the first opening, the first opening being disposed adjacent a furnace combustion air chamber upon installation. At least three tubular portions is connected to the housing portion and disposed adjacent to the second opening. Each of the at least three tubular portions defines a central axis and has a first opening adjacent the second opening of the housing portion and a second opening configured to receive an inlet air duct, wherein the central axis of at least one tubular portion is disposed at an angle to the central axes of the other tubular portions. A peripheral flange portion is connected to the housing portion and disposed adjacent the first opening of the housing portion, the peripheral flange portion having attachment means for sealably attaching the housing portion to a frame portion of a furnace. At least one removably attachable cap is provided, the at least one removably attachable cap being configured to selectively close a tubular portion not connected to an inlet air duct.  
         [0005]     The present invention is further directed to a gas furnace including a housing including a furnace combustion air chamber configured to combust a mixture of a combustible gas from a combustible gas source and air from an air duct supplying combustion air to the furnace. A transition fitting interconnects the furnace combustion air chamber to the air duct. The transition fitting includes a body having a first opening and a second opening opposite the first opening, the first opening being disposed adjacent a furnace combustion air chamber. At least three tubular portions are connected to the body and disposed adjacent to the second opening. Each of the at least three tubular portions define a central axis and have a first opening adjacent the second opening of the body and a second opening configured to receive the air duct, wherein the central axis of at least one tubular portion is disposed at an angle to the central axes of the other tubular portions. A peripheral flange portion is connected to the body and disposed adjacent the first opening of the body, the peripheral flange portion being configured to sealably attach the body to the housing. At least two removably attachable caps are provided, the at least two removably attachable caps being configured to selectively close the tubular portions of the at least three tubular portions not connected to the inlet air duct.  
         [0006]     One advantage of the present invention is that it provides the installer with flexibility in connecting the air inlet pipe from the top or bottom of the furnace, or to the side of the furnace, without having to modify any internal parts of the furnace.  
         [0007]     Another advantage of the present invention is that it reduces or eliminates the need for excessive field fabrication, elbow fittings, and custom fittings in the installation of a gas furnace.  
         [0008]     Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIGS. 1 and 2  are opposed perspective views of a three-way transition fitting of the present invention.  
         [0010]      FIG. 3  is a front view of the transition fitting of the present invention.  
         [0011]      FIG. 4  is a side view of the transition fitting of the present invention.  
         [0012]      FIG. 5  is a cross-section of the transition fitting taken along line  5 - 5  in  FIG. 3  of the present invention.  
         [0013]      FIG. 6  is a cross-section of the transition fitting taken along line  6 - 6  in  FIG. 3  of the present invention.  
         [0014]      FIG. 7  is a cross-section of the transition fitting taken along line  7 - 7  in  FIG. 4  of the present invention.  
         [0015]      FIG. 8  is a perspective view of a cap of the present invention.  
         [0016]      FIG. 9  is a side view of the cap of the present invention.  
         [0017]      FIG. 10  is a perspective view of an alternate embodiment of a three-way transition fitting of the present invention.  
         [0018]      FIG. 11  is a perspective view of an alternate embodiment of a three-way transition fitting of the present invention.  
         [0019]      FIGS. 12-14  are perspective views showing different furnace installations with the three-way transition fitting of the present invention. 
     
    
       [0020]     Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Referring to  FIG. 1 , a three-way inlet air fitting is generally designated as  10 . The fitting  10  includes a housing portion or transition portion  12  defined by a first pair of opposing side portions  14   a ,  14   b  and a second pair of opposing side portions  16   a ,  16   b . One end of each side portion  14   a ,  14   b  is connected to flange portions  18   b ,  18   c . One of the side portions  16   b  has a lip  32  extending therefrom at one edge. The remaining side portion  16   a  is connected to a flange portion  18   a  extending perpendicularly therefrom. Flange portions  18   a ,  18   b ,  18   c  include apertures  34  formed therein to correspond with apertures in the structure of the furnace, for attaching the transition portion  12  to the furnace. Other suitable techniques for attachment may be substituted for the flanges as are commonly known to those skilled in the art.  
         [0022]     First and second tubular portions  22 ,  42  cross an axis  36  of the fitting  10  at the end of the side portions  16   a ,  16   b  opposite of the flange portions  18   a ,  18   b ,  18   c  adjoining the furnace. A third tubular portion  28  having center axis  36  preferably intersects the first and second tubular portions  22 ,  42  in axial alignment with the fitting  10 . That is, axis  36  extends through axes  50 ,  52 . The intersecting tubular portions  22 ,  42 ,  28 , define three respective openings  24 ,  26  and  30 . Openings  24  and  26  are preferably axially disposed at 180 degrees with respect to each other as measured between their respective axes  50 ,  52 , and at 90 degrees axially with respect to opening  30  in third tubular portion  28  as measured from respective axis  36 . In the embodiment shown in  FIG. 1 , this arrangement substantially defines a T-configuration in fluid communication with the hollow interior of the transition portion  12 . Also, in the embodiment shown in  FIG. 1 , the tubular portions  22 ,  42  and the respective openings  24 ,  26  do not share the same axis ( 50 ,  52 ), but the two axes  50 ,  52  are offset and parallel to each other. In yet another embodiment of the invention, the two axes  50 ,  52  may coincide. Thus, as discussed in additional detail below, a burner chamber of a furnace to which the transition portion  12  attaches may be easily directly interconnected with an inlet air duct extending either horizontally or vertically therefrom, without requiring specially designed fittings or other adapter to be field installed.  
         [0023]     Referring to  FIGS. 1-7 , the transition portion  12  opens into the burner chamber of the furnace through an opening  40 . The side portion  16   a  preferably tapers generally symmetrically from flanges  18   b ,  18   c  to form a connection with first tubular portion  22 . An opening  44  allows inlet air to flow between tubular openings  24 ,  26  and  30 , and opening  40  into the furnace. As described below, two of three tubular openings  24 ,  26  and  30  are closed once the remaining tubular opening is connected to an air duct to provide a source of combustion air. Preferably, a cap  54 , as shown in  FIGS. 8 and 9 , is used to close two of the three openings  24 ,  26  and  30 . Side portions  14   a ,  14   b  terminate at the edges of tapered side portions  16   a ,  16   b  to enclose the air passage within the transition portion  12 .  
         [0024]     Also shown in  FIGS. 8-9  are caps  54  that are removably attached to any two of the three tubular portions  22 ,  28  and  44  to seal all but one of the respective openings  24 ,  26 ,  30 . In practice, only one of the openings  24 ,  26 ,  30  is connected to an air inlet duct (not shown), although more than one opening could be connected to multiple inlet ducts if desired. The installer determines which opening of the three openings  24 ,  26 ,  30  is selected according to the most convenient routing to an outside air source of the building via inlet duct  108 . If the selected opening has a cap  54  affixed to it, the cap  54  is simply removed to provide the uncapped opening. The selected opening is then capable of interconnection with the air inlet duct. Thus the fitting of the present invention provides the installer the option of three directional openings for connection to a single inlet air duct.  
         [0025]     Cap  54  includes a tapered surface  58  defining a portion of a circular cone for insertion into the tubular openings  24 ,  26 ,  30  to provide a fluid tight, frictional joint. The cap  54  includes a rib  56  to provide an installer with sufficient leverage to removably install the caps  54  as required.  
         [0026]     Referring back to  FIGS. 1-7 , tubular portions  22  and  42  are preferably disposed on opposite sides of fitting  10 . First tubular portion  22  penetrates side portion  16   a  and second tubular portion  42  penetrates side portion  16   b . Third tubular portion  28  is arranged substantially perpendicular to both first tubular portion  22  and second tubular portion  42 , although first and second tubular portions  22 ,  42  are not necessarily aligned coaxially. In the embodiments that are illustrated in  FIGS. 1-7 , first and second tubular portions  22 ,  42  have respective parallel center axes  50 ,  52  that are slightly offset, although the tubular portions may also share the same axis in an alternate embodiment (not shown). As shown in  FIG. 2 , the tubular portions  22 ,  42  and  28  are configured in an inverted T, allowing the furnace installer the options of a direct connection to the inlet air duct in the vertical direction, and in both directions horizontally. Alternately, depending upon the furnace interface with the fitting, the inverted T can allow the furnace installer the options of a direct connection to the inlet air duct in the horizontal direction and in both directions vertically. It should be noted that the orientation of the fitting  10  is fixed with respect to the position of the furnace, which may be placed in various orientations, e.g., for upward air flow, downward air flow or for horizontal air flow. Irrespective the orientation, tubular portions  22 ,  42 , and  28  each have incorporated therein means to prevent an inlet duct from being inserted overly far within the fitting  10 . For example, if an inlet duct were inserted too far inside first tubular portion  22  so as to extend past the transition portion  12 , the fitting could not operate properly, since the opening to the transition portion  12  would be closed by the inlet duct, preventing sufficient air from flowing to the burner chamber. To achieve insertion depth control in the first tubular portion  22 , referring to  FIG. 5 , side portion  16   a  extends to form an annular stop  46 , resembling a “C” in  FIG. 5 . Similarly, referring to  FIG. 6 , a pair of opposed stops  48  extend inwardly from respective side portions  14   a ,  14   b  within opening  26 . Moreover, referring to  FIGS. 2 and 3 , it is shown that side portion  16   a  will act as a stop to prevent over-insertion of an inlet duct in third tube portion  28 .  
         [0027]      FIGS. 12-14  are directed to a furnace  100  that includes a burner chamber  110 , which is secured to the transition portion  12  of the fitting  10 , which fitting  10  also being connected to an inlet duct  108  for providing outside air to the burner chamber  110 . In  FIG. 12 , the inlet duct  108  extends vertically downward, and via a single elbow fitting  112 , can be configured so that only an additional straight segment of the inlet duct  108  is required to connect with the fitting  10 . As shown in  FIG. 12 , the inlet duct  108  is directed through an aperture  104  formed in a furnace panel  102   a  opposite the end of the furnace  100  containing the burner chamber  110 . Optionally, a removable cap  106  can be used to close an aperture  104  in each of panels  102   b ,  114  that are adjacent to the fitting  10 . Otherwise, the cap  106  can be in the form of a knock-out, such as commonly used in the art.  
         [0028]     As shown in  FIG. 13 , similar to  FIG. 12 , the inlet duct  108  extends vertically downward, and via a single elbow fitting  112 , can be configured so that the end of the elbow fitting  112  opposite the end connected to the vertically disposed portion of the inlet duct  108  directly connects with the fitting  10 . However, in  FIG. 13 , the elbow fitting of inlet duct  108  is directed through an aperture  104  formed in a furnace panel  102   b  adjacent the end of the furnace  100  containing the burner chamber  110 . Optionally, a removable cap  106  can be used to close the aperture  104  in each of panels  102   a  and  114 . Otherwise, the cap  106  can be in the form of a knock-out, such as commonly used in the art.  
         [0029]     Finally, as shown in  FIG. 14 , the inlet duct  108  extends vertically upward and can be configured to directly connect with the fitting  10 . However, in  FIG. 14 , the inlet duct  108  is directed through an aperture  104  formed in a furnace panel  114  adjacent the end of the furnace  100  containing the burner chamber  110 . Optionally, a removable cap  106  can be used to close the apertures  104  in each of panels  102   a  and  102   b . Otherwise, the cap  106  can be in the form of a knock-out, such as commonly used in the art.  
         [0030]     It is to be understood that openings  24 ,  26  are not required to be disposed at 180 degrees to each other, as these openings could be disposed at angles that are significantly less than 180 degrees. For example, referring to  FIG. 10 , first tubular portion  22  extends so that opening  24  is associated with axis  150  and second tubular portion  42  extends so that opening  26  is associated with axis  152 , which angle between axis  150  and axis  152  being significantly less than 180 degrees, and conceivably parallel to each other. Similarly, it is also to be understood that opening  30  is not required to be disposed 90 degrees axially from openings  24 ,  26 . In other words, third tube portion  28 , as measured from axis  136 , can define an angle measuring anywhere between zero and 180 degrees from each of axis  150  of opening  24  and axis  152  of opening  26 . However, since most air inlet ducts extend substantially parallel to the ceiling, walls and floor which are mutually perpendicular to each other, the embodiment as shown in  FIG. 1  is preferred.  
         [0031]      FIG. 11 , which is otherwise similar to  FIG. 10 , includes joints  60  for each of the tubular portions  22 ,  28 ,  42  to permit an amount of angular adjustability of each of the tubular portions  22 ,  28 ,  42 . For example, first tubular portion  22  extends to an additional first tubular portion  122 , first tubular portion  22  and first tubular portion  122  being separated by joint  60 , which permits a relative sliding rotational motion about axis  50  between the first tubular portion  122  and the first tubular portion  22 . That is, by applying a rotation  62  of the first tubular portion  122  about axis  50  by virtue of joint  60 , axis  150  traces a periphery of a circular cone  64 , providing angular adjustment of the position or orientation of axis  150  between axis  150  and an axis  150 ′.  
         [0032]     Similarly, second tubular portion  42  extends to an additional second tubular portion  142 , second tubular portion  42  and second tubular portion  142  being separated by joint  60 , which permits a relative sliding rotational motion about axis  52  between the second tubular portion  142  and the second tubular portion  42 . That is, by applying a rotation  62  of the second tubular portion  142  about axis  52  by virtue of joint  60 , axis  152  traces a periphery of a circular cone  64 , providing angular adjustment of the position or orientation of axis  152  between axis  152  and axis  152 ′.  
         [0033]     Additionally, third tubular portion  28  extends to an additional third tubular portion  128 , third tubular portion  28  and third tubular portion  128  being separated by joint  60 , which permits a relative sliding rotational motion about axis  36  between the third tubular portion  128  and the third tubular portion  28 . That is, by applying a rotation  62  of the third tubular portion  128  about axis  36  by virtue of joint  60 , axis  136  traces a periphery of a circular cone  64 , providing angular adjustment of the position or orientation of axis  136  between axis  136  and axis  136 ′.  
         [0034]     In addition to angular adjustment of tubular portions  122 ,  142  and  128  about respective axes  50 ,  52  and  36 , the first tubular portion  22  can be configured so that the first tubular portion  22  is rotatable about axis  50  with respect to transition portion  12 . The effect of imparting a rotation  64  of first tubular portion  22  about axis  50  similarly imparts a rotation about axis  50  of the third tubular portion  28  and the third tubular portion  128 . That is, by applying a rotation  64  of the third tubular portion  28  and the third tubular portion  128  about axis  50 , the orientation of axis  36  of the third tubular portion  28  becomes axis  36 ′, and the adjustable orientation of axis  136  between axis  136  and  136 ′ of the third tubular portion  128  as previously discussed above becomes between axis  136   a  and  136   a′.    
         [0035]     In summary, while fitting  10  can include a fixed, unitary construction as shown in  FIG. 1 , other embodiments of the fitting can include any combination of adjustments of the angular position or orientation of axes of the tubular portions.  
         [0036]     The embodiments shown in the figures are examples of several configurations and are not intended to limit the scope of the invention.  
         [0037]     One skilled in the art can appreciate that the fitting of the present invention can be constructed of metal or a polymer or other suitable material having sufficient structural strength and compatibility with a heating system.  
         [0038]     It is also to be understood that the fitting of the present invention can include more than three tubular portions. The axes of the tubular portions can be disposed at angles other than 90 or 180 degrees, and the angular position or orientation of any one combination of the tubular portions can also be adjustable. The fitting can also be of unitary construction. In addition, more than one of the tubular portions can be connected to an inlet duct, the tubular portions connected to inlet duct(s) not requiring caps.  
         [0039]     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.