Abstract:
An HVAC air handling enclosure is comprised of individual panel assemblies each of which are fabricated from two panels or skins that are held together by double-sided adhesive tape. Adjacent panel assemblies are connected by a metal tongue-and-groove joint that relies on that same tape as a thermal break at the joint. After assembly, the thermal break and the tongue and groove elements of the joint are completely hidden from view. Moreover, the joint includes an internal cavity that can take up surplus sealant that may ooze out from within the tongue-and-groove joint during assembly, whereby the surplus sealant also remains hidden.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The subject invention generally pertains to HVAC air handling enclosures and more specifically to a thermal break and panel joint for such an enclosure. 
   2. Description of Related Art 
   Heat exchangers, compressors, blowers, filters and other HVAC equipment are often housed within an air handling enclosure. The enclosure helps shelter the equipment, provides a sound barrier, and perhaps most importantly, the enclosure provides a conduit for directing the air through the equipment. Air handling enclosures usually comprise a number of sheet metal panels that are interconnected to create a box-like structure. 
   In many cases, the panels are insulated to minimize heat loss between the interior and exterior of the enclosure. Although such insulation can improve the operating efficiency of the air handling system, some localized heat loss may still occur at the uninsulated metal-to-metal joint where two panels come together. Such localized heat loss may be inconsequential to the system&#39;s overall efficiency; however, when there is a significant temperature differential between the interior and exterior of the enclosure, condensation may form on the joint. The condensation can lead to poor air quality, water damage or create a wet, slippery floor around the enclosure. In some cases, the condensation may freeze, and the accumulating frost can provide a poor appearance or prevent doors or other moving parts of the enclosure from operating. 
   Some enclosures have a non-metallic seal that lines one or more edges of each panel. Examples of such seals are disclosed in publication WO 94/24493 and U.S. Pat. Nos. 6,676,234 and 2,647,287. These seals, however, are visible and may be exposed to sunlight whose ultraviolet radiation may hasten their deterioration. Moreover, some consider exposed seals unsightly. U.S. Pat. No. 6,374,571 shows how a panel with a hidden seal can be attached to a frame member, but then, of course, the enclosure requires a frame, which adds cost to the enclosure. 
   Consequently, a need exists for providing an air handling enclosure with insulated panels and a hidden thermal break at the joints without having to add a frame to help support the panels. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide an air handling enclosure with self-supporting insulated panels that include a hidden thermal break at the joints. 
   Another object of some embodiments is to provide a seal that serves as both a thermal break and a fastener for holding a panel&#39;s inner and outer skins together. 
   Another object of some embodiments is to use double-sided tape that serves as both a thermal break and a fastener for holding a panel&#39;s inner and outer skins together. 
   Another object of some embodiments is to provide a thermal break for a joint that connects two panels end-to-end in direct contact with each other (i.e., in metal-to-metal contact with the exception of an inconsequential layer of paint or some other relatively thin coating). 
   Another object of some embodiments is to provide a panel with an edge that lies at a slight acute angle to the face of the panel so that when the edge abuts a similar edge of an adjoining panel, the two panels close any visible gap that might otherwise exist. 
   Another object of some embodiments is to connect two panels with a solid metal-to-metal tongue-and-groove joint, and yet provide that solid joint with a thermal break. 
   Another object of some embodiments is to connect two adjoining panels with tongue-and-groove joint that allows a sealing compound to be introduced deeply inside the groove. If any compound oozes out from within the groove, the slightly angled edges of the panels create a cavity to take up any excess compound so that the entire sealing compound preferably remains hidden between the joint. 
   Another object of some embodiments is to connect two panels with a tongue-and-groove joint, wherein the tongue and groove are formed as an integral extension of the panel sheets that provide the outer faces of each panel, thereby minimizing the number of parts and maximizing the panels&#39; strength. 
   Another object of some embodiments is to provide a panel assembly with one tape held in compression and one held in tension, whereby the opposing forces provide a tight resilient connection within a tongue-and-groove joint. 
   One or more of these and/or other objects of the invention are provided by an air handling enclosure whose individual panel assemblies are taped together, and adjacent panel assemblies are connected by a tongue-and-groove joint that relies on that same tape as a thermal break at the joint. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of an air handling enclosure. 
       FIG. 2  is a cross-sectional view taken along line  2 - 2  of  FIG. 1 . 
       FIG. 3  is a cross-sectional view taken along line  3 - 3  of  FIG. 1 . 
       FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 1 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows an air handler  10  comprising an enclosure  12  that contains a heat exchanger  14 , a blower  16 , compressor, filter, or some other type of HVAC equipment. Enclosure  12  is open to an inlet  18  and an outlet  20  for conveying air across the equipment housed within the enclosure. The equipment inside enclosure  12  is used in some manner to handle or condition air associated with an HVAC system. Since a temperature differential usually exists between the enclosure&#39;s interior and exterior, enclosure  12  is preferably insulated. 
   Enclosure  12  can be made of any number of insulated panel assemblies  22 ,  24 , 26 ,  28 , and  30  that have a thermal insulating core sandwiched between inner and outer panel sheets. The inner and outer panel sheets are held together with double-sided tape. The tape also provides a thermal break where adjoining panel assemblies come together at a tongue-and-groove joint. Details of some embodiments of assemblies  22 ,  24 ,  26 ,  28 , and  30  are shown in  FIGS. 2-4 . 
   Referring to the right side of  FIG. 2  and the left side of  FIG. 3 , panel assembly  24  comprises a thermal insulating core  34  between an outer panel  36  and an inner panel  38 , wherein panels  36  and  38  are both made of sheet metal and are taped together. Examples of thermal insulating core  34  include, but are not limited to, foam injected between panels  36  and  38 , or conventional fiberglass. To interconnect any number of panels assemblies end-to-end using a tongue-and-groove joint  40 , panels  36  and  38  are formed to create a tongue  42  at one end  44  ( FIG. 3 ) and a mating groove  46  at an opposite end  48  ( FIG. 2 ). 
   At end  48  ( FIG. 2 ), outer panel  36  is formed from a single piece of sheet metal to create an outer groove edge  50  that leads to an outer groove flange  52 . Likewise, inner panel  38  is formed to create an inner groove edge  54  that leads to an inner groove flange  56 . A strip of double-sided tape  58  (i.e., adhesive on both sides) holds flanges  52  and  56  in a generally fixed spaced-apart relationship to create groove  46 . Although various types of tape could be used, in a currently preferred embodiment, tape  58  is 0.25″ thick by 0.5″ wide (e.g., P/N DKARS119 by Duraco, Inc. of Forest Park, Ill.). 
   At end  44  of panel assembly  24  ( FIG. 3 ), outer panel  36  is formed to create an outer tongue edge  60  and an outer tongue flange  62 . Likewise, inner panel  38  is formed to create an inner tongue edge  64  and an inner tongue flange  66 . Another strip of double-sided tape  68  holds flanges  62  and  66  together to create tongue  42 . In this case, tape  68  is 0.125″ thick by 0.75″ wide (e.g., Duraco P/N DKAR150). 
   Panel assembly  22  is similar to panel assembly  24  in that assembly  22  comprises an outer panel  70 , an outer tongue edge  72 , an outer tongue flange  74 , an inner panel  76 , an inner tongue edge  78 , an inner tongue flange  80 , insulating core  34 , and a strip of double-sided tape  82  that bonds inner tongue flange  80  to outer tongue flange  74  to create a tongue  84 . An opposite end  86  of panel assembly  22  could be similar to an end  92  of panel assembly  26 , or in some cases, end  86  could be similar to end  48 . For strength and ease of manufacture, the inner panels and their metal tongue and groove elements are formed from a unitary piece of sheet metal. The same is true for the outer panels. For panel assembly  24 , for example, outer panel  36 , outer groove edge  50 , outer groove flange  52 , outer tongue edge  60 , and outer tongue flange  62  comprise a unitary piece. 
   To connect panel assemblies  22  and  24  together, an adhesive sealant  90  is injected into the base of groove  46  prior to inserting tongue  84  of panel assembly  22  into groove  46  of panel assembly  24 . Sealant  90  not only provides an effective seal at joint  40 , but the adhesive properties of sealant  90  helps hold panel assemblies  22  and  24  together. A variety of adhesive sealants could be used, but in a currently preferred embodiment, sealant  90  is a 221-Sikaflex sealant provided by Sika Corporation of Baar, Switzerland (with various branch locations including Lyndhurst, N.J.). 
   To provide a clean, attractive joint, edges  50 ,  54 ,  72  and  78  each lie at a slightly acute angle  88  to its respective panel  36 ,  38 ,  70  and  76 . Angle  88  is between 80 and 90 degrees and is preferably about 88-degrees. Angle  88  ensures that the two adjoining outer panels  36  and  70 , and the two adjoining inner panels  38  and  76  come in direct contact with each other at the surface where panel assemblies  22  and  24  are most visible. Angle  88  also creates a gap  94  between edges  50  and  72 , and between edges  54  and  78 . Gap  94  provides a space into which surplus sealant  90  can ooze without being noticeable once enclosure  12  is assembled. 
   It should be noted that although tape strips  58 ,  68 , and  82  couple inner panels  38  and  76  to outer panels  36  and  70 , the tape strips also provide a thermal break between the inner and outer panels, as strips  58 ,  68 , and  82  have a much lower thermal conductivity than the sheet metal material of the panels. To provide a resiliently tight fit at the tongue-and-groove joint  40 , tape  58  is in tension, and tape  82  is in compression. If a metal stiffener  96  is added between the inner and outer panels, a strip of double-sided tape  98  can provide a thermal break for that as well. 
     FIG. 3  shows how a joint  100  similar to joint  40  can be used to join two panel assemblies  24  and  26  at a vertical corner of enclosure  12 . Panel assembly  26  comprises an outer panel  102  and an inner panel  104  that are formed to create a groove  106  similar to groove  46 . Panel assemblies  24  and  26  can then be joined by simply inserting tongue  42  into groove  106 . 
     FIG. 4  shows how upper panel assembly  30  can be attached to a side panel assembly, such as panel assembly  26 . Upper panel assembly  30  can be comprised of a series of interconnected panels, similar to the way panels  22  and  24  are interconnected to make one complete side of enclosure  12 , or upper panel assembly  30  can simply comprise just one outer panel  108  attached to an inner panel  110 . A tape strip  112  bonds an end cap  114  (similar or identical to stiffener  96 ) to outer panel  108 . Likewise, a tape strip  116  bonds an end cap  118  to outer panel  102  of side panel assembly  26 . A fastener  126  (e.g., sheet metal screw, or screw that is self-drilling and self-tapping) can be used for attaching an angle member  122  to side panel assembly  26  with a sealant  120  between the two. In some embodiments, sealant  120  comes as strip of moldable material that flows upon being compressed between two parts. One example of sealant  120  is SikaLastomer-95 provided by Sika Corporation of Baar, Switzerland (with various branch locations including Madison Heights, Mich.). Another screw  126  can fasten upper panel assembly  30  to angle member  122  and end cap  118 . A sealant  124 , similar or identical to sealant  120 , can be pressed between assembly  30  and angle  122 . Screws  128 , similar or identical to screws  126 , can fasten an angle member  130  to cover the joint. Tape strips  112  and  124  serve as fasteners and thermal breaks. Screws  126  and sealant strips  120  and  124  prevent air bypass at the upper joints. 
   Although the invention is described with respect to a preferred embodiment, modifications thereto will be apparent to those of ordinary skill in the art. Therefore, the scope of the invention is to be determined by reference to the following claims.