Patent Publication Number: US-2010112928-A1

Title: Adaptable exhaust box

Description:
TECHNICAL FIELD 
     The invention relates to an exhaust box for mounting in the exterior wall of a building to exhaust air from building ducts through the exterior wall. 
     BACKGROUND OF THE ART 
     The rooms of residential, commercial and industrial buildings are exhausted and air circulated using various fans, blowers and are ducts. Moisture, contaminated air and dust are drawn from rooms and conveyed through ducts to roof vents or exhausted through exterior walls. 
     Conventional ducts used in residential buildings are cylindrical or rectangular tubes made of sheet metal, flexible corrugated metal or plastic. In the present description and drawings only cylindrical ducts are used as an example, however it will be understood that the invention can accommodate any conventional duct type to equal advantage. 
     Conventional exterior wall exhaust boxes are mounted in an exterior wall through an opening in the wall structure, through a portion of a window frame or an upper part of a door frame. The exhaust boxes may be difficult to access after construction and therefore long term maintenance-free service is important. 
     For example, high rise apartments or condominiums may have exhaust boxes through walls many stories above the ground that exhaust bathrooms and kitchens of the high rise unit. Moisture laden air exhausting outdoors will result in water condensation on colder surfaces of the exhaust box. 
     Excessive condensation will enable mildew, mold and even fungi to grow within the exhaust box and adjacent ducts. Such growth absorbs even more water causing metal corrosion. Fungal and mold spores create a health hazard. Runoff of precipitation that enters the exhaust box can cause staining of the adjacent building wall. Excessive growth can interfere with check valves or seals that prevent outside air inflow into the building ducts. Therefore prevention of moisture buildup is an important goal of exhaust box design. 
     It is preferable to have the least number of wall openings in a building as possible, to minimize air infiltration and insulation problems. Typically an apartment or condominium unit will have a kitchen exhaust fan over the stove and exhaust fans in each bathroom. The number of ducts and sizes of ducts that join to the exhaust box may vary considerably. For example, ducts of 4, 5 or 6 inch diameter may be commonly used in a single dwelling unit and the number of bathrooms varies resulting in between 1 to 4 ducts joining to a single exhaust box. 
     Conventionally, due to the variety of possible combinations of duct sizes and numbers, exhaust boxes are manufactured to order. Contractors and purchasers must specify the number of ducts, the duct diameters and the specific order in which ducts are arranged. If mistakes are made in ordering exhaust boxes, or if changes are made during construction, the conventional exhaust boxes cannot be easily modified on site. Changes to the ducting and exhaust boxes results in significant construction delays, increased costs and wasted materials. 
     Therefore it is desirable to have a wallbox design that is adaptable to the inevitable changes that occur during construction, simple enough to fabricate on a very short notice and of standard components to minimize the inventory required by a manufacturer. 
     Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below. 
     DISCLOSURE OF THE INVENTION 
     The invention provides an air exhaust box, for mounting in an exterior building wall and connecting to at least one exhaust duct, includes: a housing having side walls, a rear wall and a front exhaust opening; the front opening having a mounting flange surrounding a periphery of the opening and extending outwardly from the side walls; the rear wall having an inlet opening greater than a predetermined maximum dimension; each of the side walls being joined to the rear wall at an angle less than 90 degrees; and a duct adapter having a cover removably mountable to the rear wall with removable fasteners, the cover having an outer dimension larger than said maximum dimension of the inlet opening and a rearwardly projecting duct sleeve with an inner opening of size between said maximum dimension and a minimum dimension. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       In order that the invention may be readily understood, one embodiment of the invention is illustrated by way of example in the accompanying drawings. 
         FIG. 1  is a perspective view of the front-top of an exhaust box with three inlet openings and showing three adapters with three different diameter sized duct sleeves. 
         FIG. 2  shows the exhaust box of  FIG. 1  in a vertical position to indicate that the exhaust box can be installed with any sloped side wall downward. 
         FIG. 3  is a front view of the exhaust box of  FIG. 1  showing the front flange and rear wall with three inlet openings separated by baffle walls. 
         FIG. 4  is a side view of the exhaust box showing the insertion of the adapter with duct sleeve extending rearwardly through the inlet opening. 
         FIG. 5  is a perspective view of a three opening exhaust box with three adapters of equal size. 
         FIG. 6  is a perspective view of a two opening exhaust box with two adapters of equal size. 
         FIG. 7  is a perspective view of a single opening exhaust box with a single adapter. 
         FIG. 8  is a side view, similar to  FIG. 4 , of an alternative embodiment of the exhaust box showing only the lower long side wall as sloped and the upper long side wall as horizontal. 
         FIG. 9  is a side view of the alternative embodiment of the exhaust box showing only the lower short side wall as sloped and the upper short side wall as horizontal, with baffle walls also sloped to shed moisture accumulation. 
         FIG. 10  is a front view of the alternative embodiment of the exhaust box to show the sloping baffle walls and overlapping corner portions of the walls that form the front flange. 
         FIG. 11  is a plan view of flat sheet metal blanks used to form a two opening version of the exhaust box such as shown in  FIG. 6 , using the drawing convention that solid lines indicate cuts, dashed lines indicate upward folding lines and dash-dotted lines indicate downward folding lines. 
     
    
    
     Further details of the invention and its advantages will be apparent from the detailed description included below. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows a perspective view of a front top of an exhaust box  1  which has three inlet openings  2 .  FIG. 1  also shows three different sized adaptors  3 ,  4 ,  5 , namely a four inch diameter adaptor  3  a five inch diameter adaptor  4  and a six inch diameter adaptor  4 . Each of the three adaptors  3 ,  4 ,  5  has a different size duct sleeve  6  to suit different diameters of exhaust ducts  10 . 
     Inlet openings  2  in the rear wall  14  are sized for a maximum dimension, for example 6⅛ inch inside diameter, such that the largest 6 inch outside diameter adaptor  5  can fit in any one of the inlet openings  2 , and the other smaller adaptors  3  and  4  can also be mounted through any opening  2 . Accordingly, the inlet openings  2  are all standardized to have a maximum diameter size (ex. 6.125 inch) and the adapters  3 ,  4 ,  5  are standardized with mounting screw holes  8 ,  9  having varying sizes of duct sleeves  6  on which cylindrical exhaust ducts  10  can be mounted. In the embodiment shown, the adapters  3 - 5  can be attached in position within the inlet opening  2  by installing removable screw fasteners  7  through aligned pre-drilled holes  8  and  9 . 
     The forward portion of the air exhaust box  1  is mounted in an exterior building wall, a door frame or window frame (not shown) and a rear portion of the sleeves  6  connect to at least one exhaust duct  10 . 
       FIG. 2  illustrates the exhaust box  1  of  FIG. 1  but oriented in a vertical position to indicate that the exhaust box  1  can be positioned with any one of the side walls  12 - 13  in a downward position. Since all side walls  12 - 13  are sloped or tapered towards the front exhaust opening  15 , in any orientation of the box  1 , moisture can drain forwardly out of the box  1 . 
     The assembled air exhaust box  1  is comprised of the generally rectangular housing  11  and multiple duct adapters  3 ,  4  and  5 . It will be understood that the number of inlet openings  2  and adaptors  3 ,  4  and  5  depend entirely on the specific installation and the housing can have 1 to 4 different inlet openings  2 , for example, with different sized adaptors  3 - 5  to suit any installation. Experience with residential exhaust systems shows that anywhere from 1 to 4 exhaust ducts is not unusual, but it will be understood that the invention is not restricted to any number or size of duct adapters  3 - 5 . 
     As best seen in  FIGS. 3 and 4 , the housing  11  in the illustrated example has trapezoidal shaped sidewalls namely long sidewalls  12  and short sidewalls  13 . The complete housing has a rear wall  14  and a front exhaust opening  15  to which the side walls  12 - 13  connect. Conventional galvanized sheet metal cutting, bending, spot welding and fastening methods can be used and need not be explained in detail. 
     The front exhaust opening  15  has a rectangular mounting flange  16  surrounding the periphery of the front exhaust opening  15  and the flange  16  extends a short distance outwardly from the side walls  12  and  13 . The flange  16  is used to reinforce the front opening  15  as well as provide a flush surface for installation and sealing to the exterior of the building wall. 
     The rear wall  14  has inlet openings  2  that are greater than a predetermined maximum dimension. In the example illustrated, the maximum dimension is 6 inches, the outer diameter of the largest adaptor  5  sleeve  6 , and the opening is 6.125 inches to provide adequate clearance. 
     As best seen in  FIG. 4 ,  FIGS. 1 and 2 , each of the side walls  12  and  13  is joined to the rear wall  14  at an angle less than 90 degrees, by bending a sheet metal blank for example to form the flange  16 .  FIG. 4  illustrates the angle a indicating that the side walls  12  and  13  are all sloped in a generally trapezoidal shape. This sloping of all sidewalls  12 - 13  enables moisture, from condensation of the exhaust air and from infiltration of precipitation, to drain towards the front exhaust opening  15  and then be expelled from the building. 
     Further, moisture from within the exhaust housing  11  cannot penetrate into the adjacent insulation or building materials since the edges between sidewalls  12 - 13 , flange  16  and rear wall  14  are bent from sheet metal blanks or are otherwise water sealed with caulking, gaskets or water resistant coatings. The interior surface of the exhaust box  1  can be coated with mold and mildew resistant herbicidal compounds to reduce the risk of contamination. 
     As indicated in  FIGS. 1 and 2  because all four walls, namely the long side wall  12  and short side walls  13 , are equally tapered, any one of the walls  12  or  13  can be positioned during installation in a down position without risk of moisture build-up. This orientation need not be specified when ordering the wall box  1 . Further, the tapering of the side walls  12  or  13  enables the manufacture to stack or nest the housings  11  during manufacture to the minimize storage space required. 
     As seen in  FIGS. 1 and 4 , each duct adaptor  3 ,  4  and  5  has a cover  17  that is mounted to the rear wall  14  with removable fasteners such as screws  7 . The cover  17  has an outer dimension larger than the maximum dimension of the inlet openings  2  in order to cover the openings  2  in a generally air tight manner. A gasket or caulking could be positioned between the cover  17  and the rear wall  14  to seal against moisture and air penetration if desired. The rearwardly projecting duct sleeves  6  have an inner opening of size selected between the maximum dimension of the inlet openings  2  and a minimum dimension to fit on various sized exhaust ducts  10 . 
       FIGS. 5 ,  6  and  7  show various arrangements which are possible using the invention.  FIG. 5  shows a perspective view of a three-opening exhaust box housing  11  with three adaptors  5  all of equal size. Alternatively,  FIG. 6  shows a perspective view of a two-opening exhaust box housing  11  with two adaptors of equal size  5 .  FIG. 7  shows a single opening exhaust box housing  11  and a single adaptor  5 . It will be understood, that the adaptors  5  can be selected of any size and the duct sleeves  6  can be fabricated to suit various sizes of ducts  10 . The manufacturer can stock pre-fabricated housings  11  and adaptors  3 ,  4 ,  5  of various sizes and numbers of openings in order to quickly assemble and shipped any combination of number of openings and size of openings to builders. Further, if any changes are required during construction, it is a simple matter to exchange the adaptors  3 ,  4 ,  5  even after the housing  11  has been fully mounted and sealed with adhesive caulking to the building wall. 
     Therefore the builder can make changes to the ducting simply by exchanging or by relocating the adapters without removing an installed housing  11  from the exterior wall of the building. During construction, especially in cold or wet climates, closing in a building against weather is a primary concern. The flexibility to change adapters  3 - 5  after mounting a housing  11  simplifies manufacture, purchasing and installation while increasing the speed at which exhaust box  1  orders can be shipped to a purchaser from a manufacturer. 
     When multiple openings  2  are used, a baffle wall  18  may be used to extend between the adjacent inlet openings  2  from the rear wall  14  to the front exhaust opening  15 . The baffle walls  18  prevent exhausted air from one duct  10  mixing with and being conducted into another duct  10  rather than exhausting from the building. The baffle walls  18  therefore prevent back flow of exhausted air and direct exhausted air through the opening  15  rather than risking exhausted air from being directed into the building by strong winds. 
     As best seen in  FIGS. 1 and 4 , the adaptors  3 ,  4  and  5  can include a forwarding projecting rectangular frame  19 . The frame  19  serves to reinforce the cover plate  17  as well as provide vertical walls into which checkvalve flap or other back flow preventive measures may be mounted in a removable manner. By using the frames  19 , it is possible to mount a checkvalve flap for example in a manner that can be easily removed, repaired or exchanged, if necessary. Further, the manufacturer can adapt different flaps to suit the frames  19  if desired. 
     As best seen in  FIG. 4 , the flange  16  on the front of the housing  11  comprises a vent over a front lip portion of each side wall  12  and  13 . The lip portions are joined to adjacent lip portions in an overlapping corner joint which is either spot welded or otherwise sealed together in a unitary flange  16 . The flange  16  provides means to abut building structure such as a window or a door frame or onto brick or other exterior surfaces. The flange  16  can be secured with caulking or a gasket to prevent moisture penetration. 
     Therefore, the wall boxes  1  provide a flange  16  that can be assembled to the wall in a leak-proof manner. Optional internal divider baffle walls  18  separate the airflows and ensure that back flow of exhausted air does not occur. Condensation is dealt with by providing four side walls  12  and  13  each with an outwardly directed taper to drain properly towards the outside surface. The exhaust box components are preferably made of galvanized sheet metal to prevent rust from moisture and weather exposure. The flange  16  is continuous and provides a weather barrier to engage with caulking and sealants. Pre-drilled holes  8  and  9  provide screw fasteners  7  with simple and accurate means for mounting adaptors  3 - 5 . 
       FIG. 8  shows a side view, similar to  FIG. 4 , of an alternative embodiment of the exhaust box  1  showing the lower long side wall  12  as sloped at angle a and the upper long side wall  12  as horizontal, oriented 90 degrees relative to the rear wall  14 .  FIG. 9  is a side view of the same alternative embodiment of the exhaust box  12  showing the lower short side wall  13  as sloped at angle a and the upper short side wall  13  as horizontal, oriented 90 degrees relative to the rear wall  14 , with baffle walls  18  also sloped to shed moisture accumulation.  FIG. 10  is a front view of the alternative embodiment of the exhaust box  1  to show the sloping baffle walls  18  and overlapping corner portions  20  of the walls  12 - 13  that form the front flanges  16 . This alternative configuration permits the exhaust box  1  to be used in horizontal and vertical orientation with the sloped side downward to shed moisture accumulation. 
       FIG. 11  is a plan view of flat sheet metal blanks used to form a two opening version of the exhaust box. A drawing convention is used where solid lines indicate cuts, dashed lines indicate upward folding lines and dash-dotted lines indicate downward folding lines. Upper and lower side wall blanks  21  are shown trapezoidal to form slopes on both long side walls  12  and with a downwardly bent flange  16  including overlapping corner portions  20  (as in  FIGS. 1-7 ). The short side walls  13  can be cut rectangular, then mounted outwardly of the rear/long side wall upward bent edges and extended beyond the edge connection with a long side wall in order to provide side wall extensions to mount the box level in a building wall. Rear and long side wall blank  22  is shown rectangular to form 90 degree corners with both short side walls  13  and with a downwardly bent flange  16  including overlapping corner portions  20 . 
     The overlapping portions  20  reinforce the corners of the flange  16  and ensure that flange  16  is continuous to seal and mount the box  1  in a building structure. The flange  16  and flat walls may be used to mount and contain insulation materials. 
     Accordingly, the invention provides a very flexible system which reduces the time in which orders are required for processing by a manufacturer. Conventional exhaust boxes are custom made to order and are not adaptable if any changes are required during construction. In contrast, the invention provides complete flexibility using standard components and reduces the variety of boxes which the manufacturer must keep in inventory. Accordingly, rapidly deployed shipments result from the use of the invention. The adaptors  3 ,  4  and  5  can be stocked in a manufacturer&#39;s facility and assembled when orders are received for housings  11  with 1 to 4 openings to suit almost any required building construction situation. 
     Although the above description relates to a specific preferred embodiment as presently contemplated by the inventor, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein.