Abstract:
An insulated ductwork system particularly adapted for exterior use joins together pre-assembled air circulation duct sections that each have a ductwork passageway that is formed solely with insulation panels of foam insulation material disposed between foil sheets that are in turn covered by additional insulation material and an outer protective jacket to seal the ductwork from weather effects. The air circulation duct sections are used without traditional metal ductwork forming any part of the air circulation duct. Receiving flanges extend from the ends of each air circulation duct section and the duct sections are joined together in abutting relation with at least one slidably engageable sleeve that engages the flanges. A filler insulation is disposed over the sleeve. A closure band is disposed over the filler insulation and joined to exterior surfaces of the air circulation duct sections.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a duct work design particularly suitable for exterior ductwork systems, in which the ductwork passageway is formed solely with insulation panels that are in turn covered by an outer protective jacket to seal the ductwork from weather effects. 
     2. Background 
     Heating, ventilation and air conditioning systems use ventilation air ducts installed throughout a building to supply conditioned air to a room through outlet vents, and ducts to remove air through return grilles. Galvanized mild steel is the standard and most common material used in fabricating ductwork. For insulation purposes, metal ducts may be lined with faced fiber glass blanket (duct liner) or wrapped externally with fiber glass blankets (duct wrap), or lined or wrapped with foams or other insulative materials. 
     Traditionally, air ductwork was made of sheet metal which was installed first and then lagged with insulation as a secondary operation. Aluminum tape was applied to all seams where the external surface of the aluminum foil had been cut. Internal joints then could be sealed with sealant. The traditional ductwork installation was highly labor intensive. 
     When used outside, the ductwork and insulation combined therewith require a weather tight seal. U.S. Pat. No. 6,360,783 discloses one improved duct work system in which insulating panels are applied externally around the metal duct. The insulating panels comprise two adjacent insulation panels. Then, an embossed metal layer extends over the outer surfaces of the outermost insulation panel. Adjacent insulating panels are joined by fasteners. The embossed metal layers overlap at some edges and are further joined by grout or adhesive to create moisture barriers at their overlapping edges and interfaces. 
     Ducting systems that use insulation panels to form the ductwork passageway without an inner sheet metal duct have been proposed for indoor use. Such systems lack stability and weather resistance necessary for exterior ductwork systems. Accordingly, improvements to ductwork systems and more weather-robust exterior ductwork systems continue to be sought. 
     SUMMARY OF THE INVENTION 
     The present invention in a first aspect is directed to an air circulation duct section that has an inner duct air passageway formed with a first insulation material having a top wall, a bottom wall and two opposed sidewalls. The first insulation material is not a traditional sheet metal duct. Solid insulation is joined to the outer surfaces of the first insulation material of the inner duct air passageway. A jacket is joined to the outer surfaces of the solid insulation. The jacket may be formed from a series of sheet sections, such as aluminum sheet, with at least some of the sections having angled flange edges that overlap adjacent jacket sections. The flange edges may be joined with fasteners to the overlapped side edges of adjacent jacket sections. A sealant or grout may be applied to the flange edges, and may be held within ribs or channels formed in the flange edges. 
     In one embodiment, the first insulation material of the inner duct passageway may be a foam insulation disposed between foil sheets. 
     Alternatively, in another embodiment, the first insulation material may include multiple insulating panels adhered or laminated together. 
     Two or more air circulation duct sections may be joined together in end to end relation in a series to form an insulated ductwork system. The joint at which two air circulation duct sections meet may be covered by filler insulation and in turn by a closure band disposed over the filler insulation and the joint. The closure band may be joined to the jackets of the air circulation duct sections with adhesive tape, such as butyl gasket tape, in combination with fasteners, such as screws. In addition, the closure band may define ribs or channels at or near its side edges to receive sealant or grout to adhere longitudinal edges of the closure band to the jackets of the air circulation duct sections. 
     Advantages of the air circulation duct sections and ductwork system will appear from the drawings and following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention described above will be explained in greater detail below on the basis of embodiments and with reference to the accompanying drawings in which: 
         FIG. 1  is a left front perspective view broken away showing one embodiment of a section of an air circulation duct system according to the invention in which two air circulation duct sections are joined together; 
         FIG. 2  shows a left front perspective view broken away showing two air circulation duct sections according to the invention prior to joining them together; 
         FIG. 3  shows a left front perspective view broken away showing the two air circulation duct sections according to  FIG. 2  in a first step of joining the two sections together; 
         FIG. 4  shows a left front perspective view broken away showing the two air circulation duct sections according to  FIGS. 2 and 3  in a second step of joining the two sections together; 
         FIG. 5  shows a cross-sectional view taken along line  5 - 5  in  FIG. 1 ; and 
         FIG. 6  shows a cross-sectional view taken along line  6 - 6  in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning in detail to the drawings,  FIGS. 1, 5 and 6  show two air circulation duct sections  10 A and  10 B joined together to form an air ductwork system passageway  100  for directing treated air in a heating, ventilation and/or air conditioning (HVAC) system. The air ductwork system passageway  100  may be used on both inside and outside installations. Each air circulation duct section  10 A,  10 B comprises an inner duct passage  12  having a top wall  14 , bottom wall  16 , sidewall  18  and sidewall  20 . In this embodiment of the invention, the top wall  14 , bottom wall  16 , sidewall  18  and sidewall  20  are formed of an insulation material such as a foam insulation material disposed between two foil sheets. One representative insulation material is a foam panel branded Kool Duct® ducting system available from Kingspan Insulation Limited and PTM Manufacturing LLC. The air circulation duct sections  10 ,  10 B of the air ductwork system passageway  100  have inner duct passageways of insulation material only, and without traditional metal ductwork. 
     Referring to  FIGS. 5 and 6 , the air circulation duct section  10 B, inner duct passage  12  has a top wall  14 , bottom wall  16 , sidewall  18  and sidewall  20 . The inner surfaces of these walls define the air passageway. The opposite surfaces of these walls are surrounded by solid insulation in the form of top layer  24 , bottom layer  26 , side layer  28  and side layer  30 . In the embodiment shown, the layers  24 ,  26 ,  28  and  30  are joined to the opposite surfaces of walls  14 ,  16 ,  18  and  20  with double-sided adhesive tape. One representative double-sided tape is 1.5 inch wide tape sold by Venture under designation 1163/74—T-766. 
     Referring now to  FIG. 6 , the layers  24 ,  26 ,  28  and  30  of solid insulation may have the same thickness and length, but may have different widths. In the embodiment shown in  FIG. 6 , the top layer  24  and bottom layer  26  have a longer width than the side layers  28 ,  30 . Portions of the widths of the top layer  24  and bottom layer  26  thus extend beyond the width of the top wall  14  and bottom wall  16  respectively. These portions contact and overlap the side edges of the side layers  28 ,  30 . 
     The solid insulation layers may be a suitable insulation board, such as insulation board with an R-6 or R-8 insulation rating value. The layers  24 ,  26 ,  28  and  30  may be of the same insulation rating, or of different insulation rating. In one embodiment, the solid insulation layers comprise KoolTherm® board available from PTM Manufacturing LLC with a thickness of 0.81 inch ( 13/16 inch) and an insulation rating of R-8. Optionally, the side edges and end edges of the solid insulation layers may be covered with a moisture barrier  74 , such as a foil tape. One such tape is a 3-inch wide adhesive foil tape. 
     An external jacket may be formed over the solid insulation layers  24 ,  26 ,  28  and  30 . The external jacket preferably comprises a material suitable to withstand weather effects of sunlight, rain, ice and snow. One suitable material for the jacket is a lightweight metal, such as aluminum. In one embodiment, the external jacket is formed with an aluminum metal sheet having a thickness of about 0.032 inch. Optionally, the aluminum metal sheet may be embossed to form a surface pattern therein. 
     In one embodiment, as shown in  FIGS. 5 and 6 , the external jacket comprises four jacket sections  32 ,  42 ,  48  and  54 . First jacket  32  is joined to the top outer surface of top layer  24 , such as with double-sided adhesive tape. First jacket  32  has a first right angle flange  34  at one side edge and a second right angle flange  36  and the opposite side edge. A first rib or channel  38  is formed in the first right angle flange  34 . A second rib or channel  40  is formed in the second right angle flange  36 . 
     Second jacket  42  is joined to the bottom outer surface of bottom layer  26 , such as with double-sided adhesive tape. Second jacket as shown in  FIG. 6  does not have any angled flanges at its side edges. 
     Third jacket  48  is joined to the outer surface of sidewall  28 , such as with double-sided adhesive tape. Third jacket  48  has a right angle flange  50  at one side edge. In this embodiment, the opposite side edge of the third jacket  48  does not have an angled flange. A rib or channel  52  is formed in the right angle flange  50 . 
     Fourth jacket  54  is joined to the outer surface of sidewall  30 , such as with double-sided adhesive tape. Fourth jacket  54  has a right angle flange  56  at one side edge. In this embodiment, the opposite side edge of the fourth jacket  54  does not have an angled flange. A rib or channel  58  is formed in the right angle flange  56 . 
     In one method, in a first step, the second jacket  42  is attached to the bottom layer  26  with double-sided adhesive tape. Then, in next steps, the third jacket  48  and fourth jacket  54  are attached to their respective sidewall layers  28 ,  30  with double-sided adhesive tape. The right angle flanges  50 ,  56  are positioned in overlapping relation over the side edges and a portion of the outer surface of second jacket  42 . Lastly, the first jacket  32  is attached to the top layer  24  with double-sided adhesive tape. The right angle flanges  34 ,  36  of the first jacket  32  are positioned in overlapping relation over the side edges of the third jacket  48  and fourth jacket  54  respectively. A sealant or grout is applied to or placed inside the ribs or channels  38 ,  40 ,  52 ,  58  to join the edges of the external jacket sections to one another. The sealant or grout forms a barrier to restrict air and moisture from penetrating through the external jacket formed from first jacket  32 , second jacket  42 , third jacket  48  and fourth jacket  54  sections. Thus, the air circulation duct section  10  construction is weather-tight, making it suitable for outdoor use, as well as indoor use. 
     Two air circulation duct sections  10 A,  10 B are joined together at a joint to form an air duct system passageway  100 . Referring now to  FIGS. 2-5 , two air circulation duct sections  10 A,  10 B are positioned in end to end relation for joining the ducts together. In a first step, shown in  FIG. 3 , slidably engageable sleeves  102 , sometimes called bayonets, are inserted onto receiving flanges  96 ,  98  extending from end edges of the inner duct passages  12 . The connection between the slidably engageable sleeves  102  and the flanges  96 ,  98  holds the ends of the air circulation duct sections  10 A,  10 B together in end to end relation whereby the air circulation system passageway is defined along the lengths of the air circulation duct sections  10 A,  10 B so joined. While just two air circulation duct sections  10 A,  10 B are shown in the Figures, it is contemplated that an air circulation passageway of any desired length may be formed by joining multiple air circulation duct sections together. An air duct passageway may include multiple air circulation duct sections joined together in series. 
     The joint openings between the air circulation duct sections  10 A,  10 B are next covered with sections of filler insulation  106 . As shown in  FIG. 4 , the top layer of filler insulation  106   a , and the bottom layer of filler insulation  106   b , have longer lengths than the side layers of filler insulation  106   c ,  106   d . Hence, the lengths of top layer and bottom layer of filler insulation  106   a ,  106   b  overlap the ends of the side layers of filler insulation  106   c ,  106   d . In one embodiment, the filler insulation  106  may comprise KoolTherm® board with a thickness of 0.875 inch and an R6 insulation rating, or may comprise polyisocyanurate foam disposed between foil sheets with suitable thickness and insulation rating. 
     Referring now to  FIG. 5 , a closure band  110  encircles the joint and covers the filler insulation  106 . The closure band  110  may be of a material suitable to withstand weather effects of sunlight, rain, ice and snow. One suitable material for the closure band  110  is a lightweight metal, such as aluminum. In one embodiment, the closure band is formed with an aluminum metal sheet having a thickness of about 0.032 inch. The closure band  110  in one preferred embodiment has a rib or channel  112 ,  114  formed along each side edge. 
     The closure band  110  is joined to the external jackets of air circulation duct sections  10 A,  10 B first with lengths of gasket tape  70 ,  72 . The closure band  110  may be made in sections, such as 8 foot long sections, that have beads or grooves along each longitudinal side or near to each longitudinal side. The gasket tape may comprise a one inch wide butyl gasket tape pre-joined to the bottom surface of the closure band  110  and covered by release paper (not shown). Two lengths of gasket tape  70 ,  72  may be applied in substantially parallel relation along the length of the closure band, with one length of tape adjacent or near each longitudinal side of the closure band. As a first step, the release paper may be removed to expose the adhesive of the gasket tape for adhesively securing the closure band to the external jackets. In addition, the closure band  110  is joined to the external jackets of air circulation duct sections  10 A,  10 B with fasteners  60 ,  62 , such as screws or bolts and seal washers. In one embodiment, the fasteners  60  are #10 stainless steel self-tapping screws (0.75 inch), and the washers  62  are weather seal washers, and the fasteners  60 ,  62  are placed on 6-inch centers around the full circumference of the duct system. In the embodiment shown in  FIGS. 5 and 6 , the fasteners  60  (screws) are positioned so as to penetrate through the butyl gasket tape  70 ,  72 . Moreover, the closure band  110  is joined to the external jackets of air circulation duct sections  10 A,  10 B by applying a full bead of sealant or grout  80  along the side edges of the closure band  110  and into the ribs or channels  112 ,  114 . The sealant or grout  80  extends around the full circumference of the duct system and forms a barrier to restrict moisture from penetrating through the closure band and the external jackets at the joint between air circulation duct sections  10 A,  10 B. 
     While embodiments of this invention have been shown and described, it will be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the following claims.