Abstract:
A complete plastic HVAC system assembled using individual plastic components for ensuring the efficient and quiet distribution of air from a central air unit to multiple distribution points and preventing heating and cooling losses, the need for installers to stock multiple sized and shaped components, the accumulation of dust, dirt and pollens during storing, installing and use on the surfaces of the individual components. The fittings have a collar sizable to fit both 6 and 7-inch pipe, whether flexible or rigid. The use of plastic fittings, duct and pipe removes the potential of injury commonly associated with conventional metal ductwork, while providing seamless components that can be configured for any type of installation and insure an air tight connection between adjoining surfaces. The individual fittings include a register boot, torpedo boot, straight boot, rigid and flexible pipe and couplers, straight and 90-degree takeoffs, a plastic duct and duct end cap.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a Continuation-in-Part Application of U.S. Ser. No. 11/254,844 filed Oct. 20, 2005 which is a Continuation-in-Part Application of U.S. Ser. No. 11/053,087 filed Feb. 8, 2005, which application is a non-provisional U.S. application, all of which are herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to heating and cooling. More particularly, but without limitation, the present invention relates to a complete plastic HVAC component system for distributing air and method for installing the same. 
         [0003]    A problem of common interest in heating and cooling is efficiency. Increasing the efficiency of a heating and cooling system results in decreased costs of operating the heating and cooling system. A key aspect contributing to the efficiency or inefficiency of a heating and cooling system is the heat and cooling losses incurred as air travels from the furnace through the ductwork and ultimately to the distribution points. 
         [0004]    Conventionally, the ductwork between the furnace and the distribution points have been formed of sheet metal. Ducts or pipes as well as fittings such as elbows, angles, couplers and boots are formed of riveted or welded sheet metal. Due to the nature in which these various parts are made there are often cracks in the ductwork and between the associated fittings that result in heating or cooling loss. Cracks can result in an undesirable whistling sound and provide an opening for insects to access the inside of the ductwork. 
         [0005]    In more recent times, flex pipe is replacing sheet metal ducts. Flex pipe is generally associated with less heat loss and is easier to handle than conventional sheet metal ductwork. 
         [0006]    Another problem relates to installation of ductwork. Metal ductwork often presents sharp edges and corners to work around to prevent injuries from resulting. 
         [0007]    A further problem relating to sheet metal ductwork is that it inherently collects dust and dirt on it&#39;s surface. In high humidity environments the surface of the sheet metal sweats collecting dust and dirt. A thin film of oil on the sheet metal&#39;s surface that is developed during manufacturing also collects unwanted dust and dirt particles during assembly and use. 
         [0008]    Another problem relating to installation and repair is inventory. Ductwork can be of various sizes, including ducts being of 6 inch diameter or 7 inch diameter. Corresponding fittings come in 6 inch or 7 inch diameter, although reducers are available. The difference in diameters of ductwork requires that those who stock ductwork to carry inventory for both dimensions. This can be of particular concern to those who install or replace ductwork as they either need to maintain a full inventory of parts. 
         [0009]    An additional problem relating to the use of sheet metal to form the ductwork and various components is the probability of incurring damage when dropped. Sheet metal components, ductwork and their connections risk becoming increasingly inefficient if dropped or subjected to excessive force during handling or installation. 
         [0010]    Therefore, it is a primary object, feature, or advantage of the present invention to improve upon the state of the art. 
         [0011]    It is a further object, feature, or advantage of the present invention to provide a complete plastic HVAC component system capable of efficiently delivering air from a furnace to distribution points having a limited number of fittings. 
         [0012]    It is a further object, feature, or advantage of the present invention to provide for a complete plastic HVAC component system having individual fittings capable of use with square and round ductwork. 
         [0013]    It is a further object, feature, or advantage of the present invention to provide for improved connections between a furnace, the ductwork and the registers to reduce losses and improve efficiency. 
         [0014]    Another object, feature, or advantage of the present invention is to provide plastic fittings that can be adapted to accommodate ductwork having different diameters. 
         [0015]    A further object, feature, or advantage of the present invention is to provide plastic fittings that reduce the amount of inventory needed. 
         [0016]    A still further object, feature, or advantage of the present invention is to eliminate sharp metal edges which can result in injury. 
         [0017]    Yet another object, feature, or advantage of the present invention is to provide fittings suitable for use with flex pipe. 
         [0018]    A still further object, feature, or advantage of the present invention is to provide fittings that are seamless and without cracks that leak air and allow insects access. 
         [0019]    Another object, feature, or advantage of the present invention is to provide fittings that are quiet and do not generate a whistling sound. 
         [0020]    Yet another object, feature, or advantage of the present invention is to provide fittings with a flange or lip to stabilize the fittings during installation. 
         [0021]    A further object, feature, or advantage of the present invention is to provide rigid fitting and/or flexible fittings that do not require an adapter to couple to different size piping. 
         [0022]    A further object, feature, or advantage of the present invention is to provide a system of HVAC components, fittings and connectors resistant against damage during storing, handling and connecting. 
         [0023]    A further object, feature, or advantage of the present invention is to provide a system of HVAC components, fittings and connectors resistant to sweating in high humidity environments. 
         [0024]    A further object, feature, or advantage of the present invention is to provide a system of HVAC components, fittings and connectors resistant against dust, dirt and pollen collection during storing, handling and use. 
         [0025]    A further object, feature, or advantage of the present invention is to provide a system of HVAC components, fittings and connectors and a method for installing the same. 
         [0026]    One or more of these and/or other objects, features, or advantages of the present invention become apparent from the specification and claims that follow. 
       SUMMARY OF THE INVENTION 
       [0027]    The present invention provides a complete plastic HVAC component system for distributing air and method for installing the same. According to one aspect of the present invention, individual plastic components, of complimentary shapes and sizes, provide a system for creating ductwork to channel air from a central air unit to multiple distribution points. The individual plastic components include torpedo boots, register boots, straight boots, flexible joints, solid pipes, duct runners and end caps, couplers, 90-degree takeoffs and straight takeoffs. The boots, flexible joint, coupler, solid pipe, 90-degree and straight takeoffs are formed of a unitary body of plastic. The boots have a unitary body with a substantially circular first opening for connecting to a flexible joint, solid pipe or flexible pipe and a substantially rectangular second opening for connecting to a register. The unitary body of the boot defines an air pathway between the first opening and the second opening. The unitary body can be adapted for connection to either a flexible joint, solid pipe, coupler or flexible duct each having a first diameter or a second diameter. The solid pipe, coupler, flexible joint and flexible pipe each have a unitary body with a substantially circular first opening and second opening for connecting to each other, a boot or a duct runner. The unitary body of the solid pipe, coupler, flexible joint and flexible pipe defines an air pathway between the first opening and the second opening. The unitary body can be adapted for connection to each other, a boot, a top and a side takeoff each having a first diameter or a second diameter. The 90-degree takeoffs and straight takeoffs are formed of a unitary body of plastic. The takeoffs have a unitary body with a substantially circular first opening for connecting to a flexible joint, solid pipe or flexible pipe and a substantially rectangular second opening for connecting to a duct runner. The unitary body of the takeoffs defines an air pathway between the first opening and the second opening. The first opening can be adapted for connection to either a flexible joint, solid pipe, coupler or flexible duct of a first diameter or a second diameter. The duct runner is formed of a sheet of plastic with sufficient thickness to resist damage during assembly, storing or installation. The plastic sheet is scored along the length of the sheet to create a hinged profile and allow for folding. A preferable method of assembling the duct runner is completed by folding the plastic sheet along the scorings, creating a rectangle shape and siliconing and screwing the raised flange to the second connecting edge. Once assemble, the duct runner is a unitary body of plastic having a substantially rectangular first and second opening for connecting to another duct runner, plenum chamber or end cap. The duct runner can also be adapted for connection to a 90-degree takeoff and a straight takeoff. Preferrably, the torpedo boots, register boots, straight boots, flexible joints, solid pipes, duct runners and end caps, couplers, 90-degree takeoffs and straight takeoffs are made of a plastic material. 
         [0028]    According to another aspect of the present invention, a complete plastic HVAC component system for distributing air and providing a tight connection between ductwork and a ducted heating or cooling system and a register to prevent loss of air while providing for ease of installation is provided. The register, straight and torpedo boots include a unitary body formed of plastic for preventing the loss of air. The unitary body has a first opening for receiving air from the pipe. The unitary body has a second opening for passing air to the register. The second opening is of a substantially rectangular shape and adapted for connection to the register. The boots are adapted to be configured to fit pipe, whether 6 inch or 7 inch in diameter. The pipe is a unitary body having a raised flange on each end and form a tight connection when connected to each other, a coupler, a straight or a 90-degree takeoff. The pipe, whether flexible or rigid, can be connected to each other by removing one of the coupling collars from an end and inserting into the end of another pipe still having the coupling collars. The 6 and 7-inch pipe connect tightly with the 6 and 7-inch collar on any of the boots, couplers or takeoffs. The takeoffs are tightly secured to the duct over top of the opening formed in the duct wall for air passage. When assembled, the components provide an efficient guide for directing air from a central unit to multiple distribution points while preventing cooling and heating efficiency losses. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a perspective view of a system for distributing air from a central air unit to various distribution points using complimentary plastic HVAC components. 
           [0030]      FIG. 2  illustrates a perspective view of one embodiment of a register boot of the present invention. 
           [0031]      FIG. 3  illustrates a perspective view of one embodiment of a torpedo boot of the present invention. 
           [0032]      FIG. 4  illustrates a perspective view of one embodiment of a register boot with flanges of the present invention. 
           [0033]      FIG. 5  illustrates a perspective view of one embodiment of a flexible coupler of the present invention. 
           [0034]      FIG. 6  illustrates a perspective view of one embodiment of a 90-degree takeoff of the present invention. 
           [0035]      FIG. 7  illustrates a perspective view of one embodiment of a straight takeoff of the present invention. 
           [0036]      FIG. 8  illustrates a perspective view of one embodiment of a rigid pipe of the present invention. 
           [0037]      FIG. 9  illustrates a perspective view of one embodiment of a straight boot of the present invention. 
           [0038]      FIG. 10  illustrates a perspective view of one embodiment of a rigid coupler of the present invention. 
           [0039]      FIG. 11A  illustrates a front view of one embodiment of a duct runner of the present invention prior to assembly. 
           [0040]      FIG. 11B  illustrates a front view of one embodiment of a duct runner of the present invention after assembly and forming a rectangular duct. 
           [0041]      FIG. 11C  illustrates a perspective view of one embodiment of a duct runner of the present invention after assembly and forming a duct. 
           [0042]      FIG. 11D  illustrates a front view of the scoring of one embodiment of the duct runner in  FIG. 11A  taken along line  11 D of the present invention. 
           [0043]      FIG. 12  illustrates a perspective view of one embodiment of a duct runner end cap of the present invention. 
           [0044]      FIGS. 13A-13C  illustrate another embodiment of a rigid pipe. 
           [0045]      FIGS. 14A-14C  illustrate another embodiment of a register duct. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0046]    The present invention provides a complete plastic HVAC component system for distributing air and method for installing the same.  FIG. 1  illustrates one embodiment of a heating and cooling system that uses various embodiments of the present invention. In  FIG. 1  a furnace  1  is shown. The furnace  1  has a plenum  2  with duct  3  extending outwardly from the plenum  2 . The duct  3  is capped using an end cap  4 . Duct openings  50  are created on the duct wall  51 . The first opening  23  of the 90-degree takeoff  6  and straight takeoff  5  are lined up flush with the duct opening  50 . The flange  27  extending perpendicularly and outwardly from the first opening  23  of the takeoffs  5 , 6  is used to secure the takeoffs to the duct wall  51 . The tight connection between the flange  27  and the duct wall  51  prevents air from passing between the flange  27  and the duct wall  51 . A 6-inch diameter pipe, whether flexible  10  or rigid  7 , is connected to the 6-inch integrated collar  16 . A rib  22  along the collar  16  retentively engages the pipes  7 ,  10  and secures the pipes against air leakage and falling off. If 7-inch diameter pipes  7 ,  10  are used, the 6-inch integrated collar  16  is removed and the pipe is connected to the 7-inch integrated collar  17  having a rib  21  for retentively engaging the pipe. A coupler, whether rigid  9  or flexible  8 , can be used to secure pipes  7 , 10  to each other. The couplers  8 , 9  have integrated collars  16 ,  17  for securing to both 6 or 7-inch pipes  7 ,  10 . Additionally, ribs  21  and  22  secure the connection between the pipes  7 ,  10  and the collars  16 ,  17  from coming apart and prevent air from leaking from the connection. Torpedo  11 , register  13  and straight  14  boots have integrated collars  16 ,  17  for connecting to both 6 and 7-inch pipes, whether flexible  10  or rigid  7  type of pipe. Both integrated collars  16 ,  17  have ribs  21 ,  22  for retentively engaging the pipe and sealing against air leakage from the first opening  23 . The torpedo  11 , register  13  and straight  14  boots each have a rectangular opening  25  and provide a means for attaching the boots to a register  52 . Thus, air is efficiently delivered from the furnace  1  to each register  52  by traveling through the duct  3 , duct opening  50 , straight 5 or 90-degree 6 takeoffs, flexible  10  or rigid  7  pipes and into a torpedo  11 , register  13  or straight  14  boot attached to the register  52 . 
         [0047]      FIG. 2  illustrates the 90 degree regular plastic register boot  13  in greater detail. The regular plastic register boot  13  includes a unitary body  15  of plastic. The plastic is preferably an injection molded thermoplastic. The unitary body  15  has a substantially circular first opening  23  for connecting to a flexible  10  or rigid  7  pipe. The unitary body  15  also has a substantially rectangular second opening  20  for connection to a register  52 . Thus air travels from the flexible  10  or rigid  7  pipe and through the first opening  23 , the unitary body  15 , the second opening  20  and to the register  52 . Due to the unitary plastic construction, the register boot is seamless thereby preventing loss of air within the register boot itself. Thus, the unitary plastic is generally advantageous over a multi-piece construction. A multi-piece construction would also tend to increase the labor required in installing the register boot. 
         [0048]    The unitary body  15  has integrated collars  16  and  17  for fitting the plastic register boot  13  to different sizes of diameter flexible  10  and rigid  7  pipe. For example, the collar  16  is preferably adapted to fit 6-inch diameter flexible  10  or rigid  7  pipe while the collar  17  is preferably adapted to fit 7-inch diameter flexible  10  or rigid  7  pipe. Because the unitary body is of a plastic material, the second collar  16  can be cut away from the first collar  17  as needed. This is advantageous because only one plastic register boot needs to be stocked as opposed to two plastic register boots. This same type of connection can also be used in other types of fittings as well. The first collar  16  has a first rib  22  and the second collar  17  has a second rib  21 . The ribs  22 ,  21 , assist in holding ductwork, preferably flexible  10  and rigid  7  pipe, in place. 
         [0049]    The unitary body  15  includes a central member  18  with a rectangular mouth  19  for connection to the register  52 . The central member  18  shown provides a 90 degree angle between the register  52  and the pipe  7 , 10 . The present invention, however, contemplates that the central member  18  can be configured differently for other angles. 
         [0050]      FIG. 3  illustrate a torpedo boot embodiment of the present invention. In  FIG. 3 , the torpedo boot plastic register boot  11  is shown. Note that the torpedo boot is similar to the regular plastic register boot shown in  FIG. 2 , however, the torpedo register boot has a torpedo boot central member  24  of a different configuration. The torpedo boot  11  has a substantially rectangular opening  25  in a rectangular mouth  26  for connection to a register  52 . Note that the torpedo register boot  11  is configured for a different type of connection than the register boot shown in  FIG. 2  as the rectangular opening  25  is oriented differently with respect to the pipe. Also, the torpedo boot plastic register boot has a first rib  22  and a second rib  21  for assisting in the connection of pipe, preferably flexible  10  or rigid  7  pipe. 
         [0051]      FIG. 4  illustrates another embodiment of a plastic register boot with a flange or lip. The plastic register boot  12  has a flange or lip  27  with a first end  28  and a second end  30  extending outwardly from the central member  33  of the plastic register boot  12 . One advantage of the flange  27  is that in floor applications the flange can be used to support the plastic register boot  12  in place during the installation process. This configuration is advantageous as it allows a single person to install the plastic register boot as opposed to requiring one person to hold the register boot in place from above with a second person working from below. Thus the flange or lip  27  provides a significant savings in the labor cost associated with installation. The flange  27  also has a plurality of tabs ( 29 ,  31  and  32 ) to assist in holding the plastic register boot in place, particularly during the installation process. Each of the tabs ( 29 ,  31  and  32 ) extend outwardly from the flange  27 . 
         [0052]      FIG. 5  illustrates a flexible coupler of the present invention. As shown in  FIG. 5 , the flexible coupler  8  includes a first opening  23  and a second opening  20  on opposite ends of the flexible coupler  8 . As the flexible coupler  8  is flexible, the flexible coupler  8  can be configured and bent at different angles to replace numerous types of angled joints associated with sheet metal ductwork pipes. The flexible coupler  8  is made of a plastic material and is adapted for fitting either different sizes of flexible  10  or rigid  7  pipe. Because the integral collars  16  and  17  are of different diameters, the flexible coupler can fit flexible  10  pipe and rigid  7  pipe of different diameters. For example, flexible pipe can fit a 6-inch diameter flexible  10  or rigid  7  pipe when the first collar  16  is in place. The first collar  16  can be cut away from the second collar  17  which can fit a 7-inch diameter flexible  10  or rigid  7  pipe. Due to the use of plastic material, the flexible coupler can be easily cut. 
         [0053]    It should also be apparent that the flexible coupler  11  can fit one size of flexible  10  or rigid  7  pipe on one hand and a different size of flexible  10  or rigid  7  pipe on the other end. Thus, a single flexible coupler  11  replaces numerous types of connectors used with sheet metal. The flexible coupler  11  includes a first rib  22  and a second rib  21  to assist in connection to ductwork, especially flexible  10  or rigid  7  pipe. When connecting to flexible  10  or rigid  7  pipe, the first rib  22  or second rib  21  helps maintain a secure connection. 
         [0054]      FIG. 6  illustrates the 90-degree takeoff  6  in greater detail. The 90-degree takeoff  6  includes a unitary body  15  of plastic. The plastic is preferably an injection molded thermoplastic. The unitary body  15  has a substantially circular first opening  23  with a flange  27  extending perpendicularly and outwardly therefrom for securing the first opening  23  over top of the duct opening  50  in the duct wall  51  of the duct  3 . The unitary body  15  also has a substantially circular second opening  20  for connection to a flexible  10  or rigid  7  pipe. Thus air travels from the duct  3  and through the duct opening  50  and the first opening  23 , the unitary body  15 , the second opening  20  and to the flexible  10  or rigid  7  pipe. Due to the unitary plastic construction, the 90-degree takeoff is seamless thereby preventing loss of air within the takeoff itself. Thus, the unitary plastic is generally advantageous over a multi-piece construction. A multi-piece construction would also tend to increase the labor required in installing the 90-degree takeoff. 
         [0055]    On the side of the second opening  20 , the unitary body  15  has integrated collars  16  and  17  for fitting the 90-degree takeoff  6  to different sizes of diameter flexible  10  and rigid  7  pipe. Note that the integrated collars are identical in feature, function and dimensions as the integrated collars used on the individual register boots in  FIGS. 2-4 . 
         [0056]    The 90-degree takeoff  6  insures seamless distribution of air from within a duct to the connecting pipe, whether flexible  10  and rigid  7  pipe. Because the plastic duct  3  is easily cut and does not present a sharp edge after cutting, duct openings  50  are safe to work in and around with one&#39;s bare hands. With sheet metal, duct openings create potential work hazard spots. However, the plastic duct wall  51  allows seamless implementation of takeoffs. Additionally, flange  27  insures that the first opening  23  lies flush and securely fastened to the duct wall  51  without risking injury or loss of air between the two surfaces. The 90-degree takeoff  6  a unitary body  15  includes a central member  18 . The central member  18  shown provides a 90 degree angle between the duct wall  51  and the pipe  7 , 10 . The present invention, however, contemplates that the central member  18  can be configured differently for other angles. 
         [0057]      FIG. 7  illustrates the straight takeoff  5  in greater detail. The straight takeoff  5  incorporates the identical features, functions, advantages and dimensions as the 90-degree takeoff except that the unitary body  15  is straight thereby providing a straight connection between the duct wall  51  and the pipe  7 ,  10 . 
         [0058]      FIG. 8  illustrates a rigid pipe of the present invention. As shown in  FIG. 8 , the rigid pipe  7  includes a first opening  35  and a second opening  36  on opposite ends of the pipe  7 . Attached to the first  35  and second  36  opening is a coupling collar  34  for connecting to a boot, takeoff, coupler or pipe. It is preferred that the rigid pipe  7  have a 6 or 7-inch diameter. The rigid pipe  7  can be connected to another section of rigid pipe  7  having the same diameter by cutting away the coupling collar  34  on the one end of a pipe and inserting into the coupling collar  34  of another section of pipe. The rigid pipe  7  having a 6-inch diameter can be connected to the integrated collar  16  of the boot, takeoff or coupler having a similar 6-inch diameter. Additionally, the rigid pipe  7  having a 7-inch diameter can be connected to the integrated collar  17  of the boot, takeoff or coupler having a similar 7-inch diameter. The rib  22  on the integrated collar  16  and the rib  21  on the integrated collar  17  help to secure the boot, takeoff or coupler to the pipe and create a seal against air leakage. 
         [0059]      FIG. 9  illustrates the straight plastic register boot  14  in greater detail. The straight plastic register boot  14  includes a unitary body  15  of plastic. The plastic is preferably an injection molded thermoplastic. The unitary body  15  has a substantially circular first opening  23  for connecting to a flexible  10  or rigid  7  pipe. The unitary body  15  also has a substantially rectangular second opening  20  for connection to a register  52 . Thus air travels from the flexible  10  or rigid  7  pipe and through the first opening  23 , the unitary body  15 , the second opening  20  and to the register  52 . Due to the unitary plastic construction, the register boot is seamless thereby preventing loss of air within the register boot itself. Thus, the unitary plastic is generally advantageous over a multi-piece construction. A multi-piece construction would also tend to increase the labor required in installing the register boot. 
         [0060]    The unitary body  15  has integrated collars  16  and  17  for fitting the straight boot  14  to different sizes of diameter flexible  10  and rigid  7  pipe. For example, the collar  16  is preferably adapted to fit 6-inch diameter flexible  10  or rigid  7  pipe while the collar  17  is preferably adapted to fit 7-inch diameter flexible  10  or rigid  7  pipe. Because the unitary body is of a plastic material, the second collar  16  can be cut away from the first collar  17  as needed. This is advantageous because only one plastic register boot needs to be stocked as opposed to two plastic register boots. This same type of connection can also be used in other types of fittings as well. The first collar  16  has a first rib  22  and the second collar  17  has a second rib  21 . The ribs  22 ,  21 , assist in holding ductwork, preferably flexible  10  and rigid  7  pipe, in place. 
         [0061]    The unitary body  15  includes a central member  18  with a rectangular mouth  26  for connection to the register  52 . The central member  18  provides a straight connection between the register  52  and the pipe  7 , 10 . 
         [0062]      FIG. 10  illustrates a rigid coupler of the present invention. The rigid coupler  9  is similar to the flexible coupler  8  shown in  FIG. 5 . Note that the difference between the flexible coupler  8  and the rigid coupler  9  is a unitary body  15  that is flexible. Particularly, the rigid coupler  9  has a rigid unitary body, whereas the flexible coupler  8  has a flexible unitary body. The rigid coupler  9  offers the benefits of rigid member. The rigid coupler  9  can also be used in situations where it supports the weight of the pipes connected thereto. 
         [0063]      FIGS. 11A-D  illustrates a duct of the present invention. The duct  3  is assembled from a sheet of plastic having sufficient wall thickness to support its own weight after assembled and resist damage during storing, assembly and installation. Particularly,  FIG. 11A  shows the plastic sheet  38  having a first  44  and second  43  connecting edge. The first connecting edge  44  has a raised flange  40  connected thereto. The plastic sheet  38  has scorings  39  running parallel and the length of the sheet  38 . The scorings  39  have a separation distance such that a rectangular duct shown in  FIG. 11B  is formed when folded along the scorings  39 . The rectangular shape of the duct  3  is retained by overlapping and connecting the raised flange  37  to the second connecting edge  43 .  FIG. 11C  illustrates the duct  3  after being constructed. The duct  3  has a rectangular body  41  connecting the first opening  35  and second opening  36 .  FIG. 11D  illustrates the scoring  39  in the plastic sheet  38  along lines  11 D as shown in  FIG. 11A . The duct  3  is easy to cut to a desired length and being plastic, is also easily cut to create openings within the duct wall  51  for securing a takeoff  5 ,  6  thereto. 
         [0064]      FIG. 12  illustrates an end cap of the present invention. The end cap is constructed of a rectangular surface  47  having an edge  48  and a wall  46 . The wall  46  is connected to the edge  48  of the rectangular surface  47 . The wall  46  extends perpendicularly and outwardly from the rectangular surface  47  forming a cap for closing off the end of a duct. 
         [0065]      FIGS. 13A-13C  illustrates another embodiment of a duct of the present invention. The duct  60  has a first open end  62  and a second opposite open end  64 . The first open end  64  is configured for coupling to another tube or duct. As shown in  FIG. 13B , an outer portion  66  is shown which slightly angles inwardly such as at a 20 degree angle. The prior art invention contemplates that the angle may vary, such as in a preferred range of 10 degrees to 30 degrees. 
         [0066]    An annular lip  68  is provided to assist in securing the connection of the duct  60  to another item or duct work. The annular lip  68  protrudes outwardly from the outer most portion  66 . After the annular lip  68 , a portion  70 , the outermost portion  66  continues to be angled slightly inwardly. The portion  70  is operatively connected to a transition portion  72  which gradually transitions to the inner portion  74 . In operation, the end  64  assists in providing a secure attachment. 
         [0067]    The duct  60  may be sized for standard sizes of duct work such as 6 inch or 7 inch. For example, the diameter of the second end may be approximately 7 inches with the diameter of the first end being slightly greater. Similarly, the diameter of the second end may be approximately 6 inches with the diameter of the first end being slightly greater. The substantially cylindrical body of the duct may have an average wall thickness of about 0.08 inches. 
         [0068]      FIGS. 14A-14D  illustrates another embodiment of a plastic register boot. The plastic register boot  80  is formed of a heat resistant plastic. There is a first opening  82  which is substantially circular and a second opening  84  which is substantially rectangular. A first collar  86  and a second collar  88  are shown. A first rib  90  is shown, a second rib  92 , and a third rib  94  are shown. Each of the ribs  90 ,  92 ,  94  are annular ribs protruding outwardly. A transition portion  96  is also shown. The transition portion  96  has a circular cross section which expands into a rectangular cross section. 
         [0069]    One skilled in the art having the benefit of this disclosure will appreciate that the present invention extends beyond the specific embodiments shown in. The present invention contemplates numerous variations in the particular type of plastic used, the manner in which the plastic if formed, the shape or configuration of the register boots, joints, or other fittings, the type of flex pipe or diameter of flex pipe that can be used, and other variations. These and other variations of the present invention are well within the spirit and scope of the invention. The present invention is not to be limited to the specific embodiments shown herein.