Abstract:
An under-floor HVAC system for a building includes a pliable air duct lying upon a subfloor. A matrix of pedestals resting upon and extending upward from the subfloor supports a set of floor panels, which thus creates a plenum between the subfloor and the set of floor panels. The air duct extends through the plenum to convey conditioned air from a supply air duct to a series of registers in the floor panels. The registers disperse the conditioned air to a room or area just above the panels. To help keep the air duct from repeatedly extending, retracting, and otherwise sliding freely along the subfloor in response to changes in air duct pressure, the air duct is held taut by anchoring a distal downstream end of the duct to one or more of the floor-supporting pedestals. Various air duct configurations can be assembled from a predefined assortment of duct components.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    This patent generally pertains to HVAC systems (heating, ventilating and air conditioning systems) and, more specifically, to under-floor air ducts. 
       BACKGROUND 
       [0002]    To heat, cool, filter, dehumidify, ventilate or otherwise condition the indoor air of a comfort zone, such as a room or area in a building, the floor of some buildings have a supply air plenum between a subfloor and a matrix of floor panels that are elevated about one or two feet just above the subfloor. The floor panels, which are usually supported by a matrix of pedestals extending upward from the subfloor, provide the surface upon which the building occupants walk and furniture is set. 
         [0003]    With an under-floor HVAC system, a supply air duct discharges fresh or conditioned supply air into the plenum, which in turn conveys the supply air to a series of supply air registers or openings in the floor panels. The registers release the supply air from within the plenum up into the comfort zone. The general goal is to have a sufficient number of properly placed registers such that the supply air rises evenly up through the comfort zone for the benefit of the occupants at floor level. As the supply air continues to rise above the occupants, the eventually used or less-than-fresh air approaches the ceiling to where one or more return air ducts extracts the air for reconditioning and/or exhausting outdoors. 
         [0004]    One problem, however, is that if the air from the supply air duct has to travel a great distance to a remote register, the supply air might lose much of its desirable temperature by heat transfer with the subfloor, particularly if the subfloor is made of concrete with a high specific heat. Also, as the supply air travels radially from the supply air duct, the air expands and loses much of its velocity. Additional velocity is lost when less remote registers release air before that air can reach more distant registers. Thus, remote registers receiving lower pressure air tend to release disproportionately less air to the comfort zone than registers that are closer to the supply air duct. 
         [0005]    To avoid these problems, some under-floor HVAC systems include a relatively rigid sheet metal air duct or a pliable tubular air duct that is installed under-floor in the plenum between the subfloor and the floor panels. Under-floor air ducts help channel supply air along a more directed route from the supply air duct to certain remote registers. A drawback of such installations, however, is that under-floor air ducts, particularly pliable ones, tend to retract and extend longitudinally in response to changes in duct pressure. The resulting sliding movement can create noise and abrade the duct material. Moreover, there are endless possible floor layouts with various supply airflow needs, thus it can be difficult and expensive to custom build numerous air duct systems to meet all those needs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a top view of an example of an under-floor air duct system with a plurality of floor panels omitted to show underlying features of the system. 
           [0007]      FIG. 2  is a cross sectional view taken along line  2 - 2  of  FIG. 3 . 
           [0008]      FIG. 3  is a top view similar to  FIG. 1  but with most of the floor panels installed. 
           [0009]      FIG. 4  is an exploded top view illustrating an example of an under-floor method. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Certain examples are shown in the above-identified figures and described in detail below. In describing these examples, like or identical reference numbers are used to identify the same or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic for clarity and/or conciseness. Additionally, several examples have been described throughout this specification. Any features from any example may be included with, a replacement for, or otherwise combined with other features from other examples. 
         [0011]    A building floor  10 , shown in  FIGS. 1-3 , includes a plurality of generally rigid floor panels  12  supported by a matrix of pedestals  14  that extend upward from a subfloor  16 . The space between subfloor  16  and floor panels  12  provides a plenum  18  for conveying fresh supply air  20  from a supply air duct  22  to a series of supply air registers  24  in floor panels  12 . Supply air  20  discharging upward through air registers  24  helps condition or ventilate a comfort zone  26  that is just above floor panels  12 . Comfort zone  26  may be any designated zone supplied with air from a HVAC system, and that may be occupied by people. 
         [0012]    To create an air duct system  28  that ensures supply air  20  is evenly distributed or properly apportioned across comfort zone  26 , a distribution air duct  30  is installed within plenum  18 . Distribution air duct  30  receives supply air  20  from a supply air chamber  32  fed by supply air duct  22  and conveys supply air  20  to wherever it is needed. Distribution air duct  30  is particularly useful for conveying supply air  20  to remote areas of comfort zone  26  that are quite distant from supply air chamber  32 . 
         [0013]    For sake of example, distribution air duct  30  is shown to include two runs, a straight run  34  and a longer L-shaped run  36 ; however, any number of runs, shapes or branches of runs are well within the scope of the methods and apparatus described herein. Although the actual construction, assembly and installation of distribution air duct  30  may vary, example runs  34  and  36  are tubes of pliable material, thus distribution air duct  30  generally inflates when pressurized by supply air  20  and tends to collapse (i.e., sag or deflate) when supply air  20  is turned off. The pliable material of distribution air duct  30  can be cloth fabric, sheets of plastic or rubber, porous, nonporous, perforated, nonperforated, and various combinations thereof. 
         [0014]    Run  34  of distribution air duct  30  comprises a pliable tubular inlet collar  38  at a proximal end  40  of run  34 , a first duct segment  42  that can be porous or nonporous, a second duct segment  44  that is preferably perforated although not necessarily so, and an end cap  46  at a distal end  48  of run  34 . To release more supply air  20  near distal end  48 , second duct segment  44  includes a series of discharge air perforations  50 . First and second duct segments  42  and  44  are examples of an upstream tubular wall section and a downstream tubular wall section, respectively, with first duct segment  42  being more air permeable than second duct segment  44 . Alternatively, or to release even more supply air  20  near distal end  48 , end cap  46  can be provided with a discharge opening  52 . The amount of supply air  20  discharged through end cap  46  can be adjusted by tightening or loosening a drawstring  54  at the throat of discharge opening  52 . An example of end cap  46  can be found in U.S. Pat. No. 6,558,250. 
         [0015]    To assemble run  34 , a strap clamp  56  fastens inlet collar  38  to a rigid tubular flange  58  that conveys supply air  20  from supply air chamber  32  to the interior of run  34 . To balance or apportion the airflow between runs  34  and  36 , a conventional baffle (not shown) can be installed within tubular flange  58 . Inlet collar  38 , first and second duct segments  42  and  44 , and end cap  46  can be joined end-to-end via any suitable fastener  60  including, but not limited to, a zipper running circumferentially around the adjoining pieces. Once assembled, run  34  of distribution air duct  30  can simply rest upon subfloor  16  for vertical support. 
         [0016]    For horizontal support, however, or to prevent run  34  from sliding around or repeatedly extending and retracting due to changes in air duct pressure, a fastener  62  preferably connects distal end  48  to one or more pedestals  14 . In some examples, fastener  62  comprises an elongate pliable member  64  (e.g., cable, strap, chain, rope, cord, wire, etc.) that connects a loop  66  (e.g., hook, snap connector, etc.) that is sewn or otherwise attached to one end of second duct segment  44 . To provide run  34  with horizontal support in two dimensions, elongate pliable member  64  can be attached to two or more pedestals  14  in a generally V-shaped layout as shown in  FIG. 1 . In the V-shaped layout, fastener  62  can be two individual elongate members or a single elongate member with two legs. 
         [0017]    To aid service personnel in maintaining or troubleshooting air duct system  28 , distribution air duct  30  preferably includes a series of decals  68  (e.g., label, tag, visual marker, sign, arrowhead, etc.) that are distributed along the upper surface of distribution air duct  30 . Decals  68  are best placed at intervals that correspond to the standard dimension of floor panels  12  so that whenever any floor panel  12  above distribution air duct  30  is lifted for service reasons, such as panel  12 ′ of  FIG. 3 , at least one decal  68  is visible. Two feet is a common standard width  70  for floor panels  12 , thus the separation between decals  68  is preferably at most two-foot. 
         [0018]    Run  36  is similar in construction to run  34 . Run  36  comprises inlet collar  38  at a proximal end  72  of run  36 , first duct segment  42 , a right-hand tubular elbow  74  made of a pliable material, a relatively long duct segment  76  that can be porous or nonporous, second duct segment  44 , and a closed end cap  78 . Similar to run  34 , strap clamp  56  fastens inlet collar  38  to tubular flange  58 , and the various pliable duct segments  42 ,  44  and  76 , inlet collar  38  and elbow  74  can be joined end-to-end by way of zippers. 
         [0019]    Run  36  includes a first distal end  80  at elbow  74  and a second distal end  82  at end cap  78 . Fastener  62 ′ and loop  66  anchors second distal end  82  to pedestals  14   a  and  14   b,  and fastener  62 ″ anchors elbow  74  to pedestals  14   c,    14   d  and  14   e.  Fasteners  62 ′ and  62 ″ each can be made of a single elongate member with multiple legs or multiple individual elongate members. 
         [0020]    Since there are endless possible floor layouts with various supply airflow needs, it can be difficult and expensive to custom build numerous air duct systems to meet all those needs. To address this problem, air duct system  28  preferably is assembled from a predefined assortment of duct segments  83 , as shown in  FIG. 4 . For sake of example, assortment  83  includes two predefined long duct segments  76 , seven predefined short first duct segments  42 , three predefined second duct segments  44 , one right-hand elbow  74 , two left-hand elbows  84 , three inlet collars  38 , two closed end caps  78 , three strap clamps  56 , and three open end caps  46 . The terms “long” and “short” as they relate to duct segments  42  and  76 , simply means that one segment of predefined length is longer than the other. It should be noted that right-hand elbow  74  and left-hand elbow  84  are unique and distinguishable from each other by virtue of the location of loop  66  and/or the orientation of their zippered joints. 
         [0021]    To create the two-run distribution air duct  30  after defining assortment  83 , one strategically chooses a collection  88  of duct segments from assortment  83 , wherein collection  88  is depicted by the parts encircled by the dashed lines in  FIG. 4 . Arrows  90  represents the assembling of collection  88  to create distribution air duct  30 , and arrow  92  represents installing of distribution air duct  30 . The assembling (arrow  90 ) of collection  88  and the installing (arrow  92 ) of air duct  30  do not have to be performed in any particular order. The assembling (arrow  90 ) of collection  88  and the installing (arrow  92 ) of air duct  30  can be done in any sequential order or done generally simultaneously. Arrows  94  and  96  each represent coupling proximal ends  40  and  72  to supply air duct  22  such that supply air  20  from supply air duct  22  can pass in series through, for example, proximal end  40 , toward distal end  48 , out from within distribution air duct  30 , into plenum  18 , up through supply air register  24  and into comfort zone  26  Once distribution air duct  30  is assembled, fasteners  62  being shown taut in  FIGS. 1 and 2  illustrate pulling distribution air duct  30  in tension generally between supply air duct  22  and at least one pedestal  14 . 
         [0022]    The just-described modular method of assembling a distribution air duct is best achieved when duct segments  42 ,  44  and  76  are of predefined lengths that are substantially whole number multiples of standard width  70 . If, for instance, standard width  70  is two feet, predefined short first duct segment  42  can be two, four, six, eight, . . . 2n feet long. The same is true for predefined long duct segment  76  but with long duct segment  76  being longer than short first duct segment  42 . 
         [0023]    At least some of the aforementioned examples include one or more features and/or benefits including, but not limited to, the following: 
         [0024]    In some examples, an air duct system for a building comprises a collection of pliable tubular segments that are assembled end-to-end to create a distribution air duct that rests upon a subfloor below a plurality of removable floor panels. To help keep the distribution air duct from sliding freely along the subfloor, the air duct is held taut by anchoring a distal downstream end of the duct to at least one and preferable two or three pedestals that help support the floor panels above the subfloor. 
         [0025]    In some examples, a distribution air duct is assembled from a collection of pliable tubular segments chosen from a predefined assortment of segments, wherein the assortment of segments are of discrete lengths based upon the width of a standard floor panel. 
         [0026]    In some examples, a distribution air duct made of one or more pliable tubes rests directly upon a subfloor, thereby eliminating the need for any overhead mounting support, such as an overhead cable or track. 
         [0027]    In some examples, a pliable distribution air duct includes a series of flow direction indicators that are distributed along the length of the duct at a spacing interval that corresponds to the width of a standard floor panel. 
         [0028]    In some examples, an under-floor distribution air duct includes an end cap with an adjustable discharge opening. 
         [0029]    Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of the coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.