Patent Publication Number: US-10330314-B2

Title: Throttled direct vent termination

Description:
BACKGROUND 
     Direct vent gas stoves and fireplaces are appliances that use a flue to vent combustion waste outside of a dwelling. Venting can occur either horizontally, through a wall, generally referred to as a rear vent, or up through the ceiling, generally referred to as a top vent. The key advantage to direct vent appliances is that they are independent of room air and use externally sourced air for combustion. 
     In direct venting, room air is not used for combustion. Rather, air used for combustion is drawn into the combustion chamber by use of a conduit which communicates with the outside ambient air. Typically, a direct vent pipe includes two ducts formed by an inner pipe surrounded by a larger diameter outer pipe. The outer pipe conveys outside air to the combustion chamber. After combustion, the exhaust is conveyed to the outside via the inner pipe. The two ducts are typically cylindrical and can be concentric, with the inlet air being conducted to the combustion chamber through an annulus outside the exhaust duct and the exhaust being conducted outside by way of the inner duct, co-linear (or side-by-side), or completely separate ducts. 
     Vent caps cover the inlet/outlet of the first and second ducts on the outside of a dwelling. Winds and drafts around the vent cap can affect the backpressure in the duct. If there is backpressure present in the exit duct, the draw of inlet air will be reduced which will decrease combustion efficiency and can lead, in poorly designed systems, to extinguishing the combustion flame. 
     SUMMARY 
     The technology includes a throttled vent termination or cap for use in conjunction with a direct vent appliance and venting system is provided. A throttle setting can be set during initial installation and if necessary changed at any time subsequent to installation. In one embodiment, the direct vent termination includes a cylindrical inner pipe and a cylindrical concentric outer housing surrounding the inner pipe to form a void between the inner pipe and the outer housing. The void is adapted to provide intake air to the air intake section of the vent system. An end cap is provided at a first end of the outer pipe, the inner pipe passing to the end cap and having an exhaust opening therein. An intake region is formed in the outer housing providing access to the void. A throttle cover which is configured to be movably positioned and thereafter secured at one of a number of positions over the intake region using a throttle guide is provided to thereby regulate air flow into the void. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  depicts a perspective, view of a direct vent termination system 
         FIG. 1B  is an exploded view of the direct vent termination system of  FIG. 1 . 
         FIG. 1C  is a front view of the direct vent termination system. 
         FIG. 2  is a top, cutaway view of the direct vent termination system along line A-A in  FIG. 1C . 
         FIGS. 3A-3C  are top views of an air intake and throttle system for the termination of  FIG. 1  illustrating the throttle in various states. 
         FIG. 4A  is a perspective view of the air intake and throttle in the position shown in  FIG. 3A-3C . 
         FIG. 4B  is a detail view of the air intake and throttle shown in  FIG. 4A . 
         FIG. 5  is a perspective view of an appliance/vent system suitable for use with the end cap of the present technology. 
     
    
    
     DETAILED DESCRIPTION 
     A unique termination system including a throttling vent cap for use in conjunction with a direct vent appliance and venting system is provided. The throttling vent cap may be used as a horizontal termination on the exterior of a building and allows independent regulation of combustion air provided to a direct vent appliance. A throttle setting can be set during initial installation and if necessary changed at any time subsequent to installation. 
     Numerous embodiments of the vent cap of the present technology are disclosed. It will be recognized that various combinations of components of each embodiment may be substituted for components disclosed with other embodiments, providing numerous variations of the cap, all of which are intended to be within the scope of the attached claims. 
       FIGS. 1-4B  show a first embodiment of the vent cap present technology. A vent cap assembly  100  includes a vent cap  105  shown in  FIGS. 1-4B  is advantageously used in conjunction with a two duct, direct vent pipe coupled to a direct vent appliance. 
     With reference to  FIGS. 1 and 2 , vent cap  105  includes an outer cylindrical housing  102  adapted to fit into a wall opening  55  in a building wall  50 . Cap  105  is mounted to the exterior of the building wall  50 . The vent cap  105  serves as the termination of a ventilation system  250  connecting the cap or termination  105  to an appliance  200 , such as that shown in  FIG. 5 . The particular nature of the venting system is not critical to the present technology, but comprises a direct vent system. A direct vent system comprises a system designed and built to exhaust gas burning appliances where the venting system comprises a sealed and balanced system with an air intake and exhaust designed into the venting. This type of venting system is a component of the appliance manufacturer&#39;s listed system. 
     The vent cap  105  is designed to be mounted to the exterior wall  50  of a building. The cap is mounted to the exterior by passing the housing  102  optionally though a stand-off box  125  and through the opening  55 . A wall thimble  140  may be used around the vent system as it passes through the wall. 
     An outer cover  120  having a first partially trapezoidal housing  121  and an second, standoff section  122  (when viewed from the top or bottom as illustrated in  FIG. 2 ) is coupled by fasteners or other suitable fastening means to wall  50  or a standoff box  125 . It will be recognized by one of average skill that alternatives exist for coupling the cover  120  to the termination system and any number of different cover shapes and styles (or no cover) may be utilized with the end cap  105 . 
     A direct vent pipe is formed by an outer housing  142  and inner exhaust pipe section  144 , which is coupled to corresponding pipe sections  102  and  104  in the vent cap  105 . An end cap  135  allows the inner pipe section  104  to pass completely through the outer pipe section to exhaust opening  130 . Spacers (not shown) may be provided between inner pipe section  104  and outer housing  102  to secure the sections to each other. The pipe sections are designed to couple to a direct vent pipe in a well-known manner. For example, the outer sleeve may include ridges to allow the pipe coupling to engage a twist lock coupling such as that commercially available from M&amp;G DuraVent Corporation, which is a bayonet-style lock allowing on end of the vent pipe to be inserted into the inner and outer pipes of the cap  105  and twisted into place to secure it therein. 
     Where pipe section  142  is cylindrical, it has a diameter D 1  which provides a perimeter P 1  (in this case a circumference) of π*D 1  and a cross-section having an area A 1 =(π*(½D 1 ) 2 ). Likewise the exhaust conduit pipe section  144  when cylindrical has a diameter D 2 , provides a perimeter (in this case a circumference) of P 2 =π*D 2  and a cross-section having an area A 2 =(π*(½D 2 ) 2 . Other shapes of pipe section  144  and wall  102  may have different cross-sectional areas, with all having a perimeter and a cross-sectional area. 
     The inner sleeve  104  and outer sleeve  102  are sized relative to the size of the connection to be made. Direct Vent Pipe such as that commercially available from M&amp;G DuraVent Company, Vacaville, Calif., is suitable for use with the present technology. Numerous sizes of direct vent pipe exist. Typical sizes are 3″×4.625″ (so called “3×4” pipe) 4″×6.625″” (often referred to as “4×6” pipe), and 5″×8, ″ referring to the diameter of the inner pipe and the outer pipe, respectively. The technology is not limited by the type or size of pipe coupled to the vent cap. 
     As illustrated in  FIGS. 2 and 3A-3C , exhaust flow  170  travels from the appliance through the inner pipe to an exhaust opening  130 . Exhaust opening  130  is covered by a screen. Intake air  180  for the appliance travels in the annular space (a void) between the outer pipe section  102  and inner pipe section  104  to a corresponding annular space formed in the venting system components (for example between pipes  142  and  144 ) from the vent cap  105  to the appliance to provide combustion air. 
     As illustrated in  FIGS. 1-4 , an intake throttle cover  110  is provided on the vent cap  105 . Apertures, which in one embodiment comprise a mesh screened section  152  having a length L, are provided in outer housing  102  to allow intake air  180  into the venting system. Due to the position of the exhaust housing relative to the air intake area in the meshed screened section  152 , little mixing of the exhaust flow  170  and the intake air  180  occurs. The apertures have an area A 3  of π(D 3 )*L. In one embodiment, the unrestricted (uncovered) area of the apertures  152  is at least 35% of the cross-sectional area of the exhaust conduit, outer pipe section  102 . 
     A throttle cover  110  is provided. Where the outer pipe  102  is cylindrical, the throttle cover may be a cylindrical ring having a circumference greater than a circumference of outer pipe housing  102  allowing the cover  110  to be slid vertically in the direction of arrow  112  in  FIG. 3A  to regulate intake flow for combustion air  180  into the appliance. A throttle guide  115  is formed in the throttle cover  110  and engages a pin  116  formed in the exterior housing  102  of the cap  105 . In one embodiment, the throttle guide takes the form of a slotted ladder having a horizontal center section or slot and any number of rotational slots (in this case, four) to engage pin  116 . By rotating the cylindrical cover  110 , the pin  116  attached to housing  102  may be rotated to a center section of the guide  115  to allow for movement in the direction of arrow  112 . Once a suitable airflow setting has been achieved, the cover  110  is rotated so that pin  116  engages one of four rotational setting slots ( 1 - 4  in  FIG. 4 b   ) to provide the regulated intake airflow. 
     The throttle cover can be constructed to cover a variable amount of the unrestricted area of the apertures, in a range of no covering to less than 100 percent covering. 
       FIGS. 3A-3C  illustrate various settings: setting  1  ( FIG. 3A ) at fully open; setting  2  ( FIG. 3B ) and Setting  4  in  FIG. 3D ; each of settings  2 - 4  leads to progressive levels of restriction. It should be understood that more or fewer settings may be provided in the throttle. In the  FIGS. 3A-3C , the relative amount of intake flow  180  is reduced by increased throttle restriction. Setting  4  is restricted, but not fully sealed. 
     In one embodiment the total unrestricted area of the aperture is at least 35% of the cross sectional area of the exhaust conduit. In one embodiment, the throttle cover  110  is capable of being adjusted to occlude at least half ½of the area of the apertures and optionally, at least 10% of the area of the apertures. 
     As illustrated in  FIG. 1A , the vent cap  104  is mounted on a planar surface (wall  50 ) and the exhaust opening  130  is positioned a distance H from the plane to the nearest part of the exhaust opening, which is no greater than 1.5 times the perimeter of the exhaust port or opening  130 . 
     As noted above, the direct vent system (including pipe sections  142 ,  144 ) has a diameter and a perimeter. Vent cap  105  also has a diameter D 3 , and a perimeter defined in terms of the diameter (or other parameters depending on the shape of the vent cap  105 ). In one embodiment, the vent cap has a perimeter of an outer housing that is less than 3 times the perimeter of the outer pipe  142  of the direct vent system to which it is connected. In one embodiment the vent cap has a perimeter of an outer housing that is equal to the perimeter of the outer pipe  142  of the direct vent system to which it is connected. 
     Vent cap  105  provides a number of advantages over the prior art. In particular, the throttle cover  110  allows tailoring of the combustion air intake based on the particulars of the installation and the appliance used. In particularly windy conditions, the intake can be reduced if needed. The specific values of L, H, the relationship between P 1  and P 3 , and the relationship between A 3  and A 2  have been empirically determined to be drivers to system performance. 
     It should be further understood that while the cap  105  is formed of cylindrical pipe sections, the teachings herein are not limited to cylindrical end caps—any shaped cap—square, rectangular, hexagonal, etc.—may incorporate the teachings of the throttling mechanism disclosed herein. 
     In yet another embodiment of the technology, the cap  105  may be used with a wall thimble, vinyl siding standoff (VSS), optional vent insulation, etc. For installations requiring a vertical rise on the exterior of the building, snorkel terminations may be utilized with the same general installation procedures as used for a horizontal termination illustrated herein. 
     Additional Aspects of the Technology 
     Embodiments of the present technology include a termination for a direct vent system, communicating with an appliance, the system having an exhaust section and an air intake section. The embodiments include a vent cap having an inner exhaust conduit and an outer housing, with a void formed between the inner conduit and the outer housing, the void coupled to the air intake section; one or more apertures communicating with the void; and a throttle cover configured to regulate air flow through the apertures into the void. 
     Embodiments of the technology include the aforementioned embodiment wherein the apertures are formed into the outer housing. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the inner exhaust conduit and outer housing comprise cylindrical pipes, the inner exhaust conduit having a smaller diameter than the outer housing. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the outer housing has a first end and a second end, and a length, the inner exhaust conduit having a length extending beyond the first end of the outer housing and including an exhaust opening. 
     Embodiments of the technology include any of the aforementioned embodiments wherein a total unrestricted area of the aperture is at least 35% of a cross sectional area of the exhaust conduit. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the throttle cover is configured to be capable of being adjusted to occlude at least 10 percent of an area of the apertures. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the throttle cover includes a throttle guide configured to set a position of the throttle cover. 
     Embodiments of the technology include any of the aforementioned embodiments the throttle guide includes a slotted ladder having a center slot and one or more rotational slots configured to set a position of the throttle cover. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the termination is mounted on a planar surface, and a distance from the planar surface to a nearest portion of an exhaust opening is no greater than 1.5 times a perimeter of the exhaust opening. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the outer housing has a perimeter less than three times a perimeter of a direct vent system to which the outer housing is connected. 
     Embodiments of the technology include any of the aforementioned embodiments comprising horizontal direct vent termination for a vent system, the vent system having an exhaust section and an air intake section coupled to the termination. In these embodiments, a termination comprises an inner pipe and an outer housing, with a void formed between the inner pipe and the outer housing, the inner pipe having an exhaust region, the inner pipe and outer housing coupled to the vent system; an end cap at a first end of the outer housing, the exhaust region passing through the end cap to an exhaust opening; an intake region formed in the outer housing providing access to the void, the intake region formed a distance apart from the exhaust opening; and a throttle cover positioned to variably cover the intake region to thereby regulate air flow into the void. 
     Embodiments of the technology include any of the aforementioned embodiments wherein a total unrestricted area of the intake region is at least 35% of a cross sectional area of the exhaust region. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the throttle cover is configured to be capable of being adjusted to occlude at least 10 percent of the area of the intake region. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the termination is mounted on a planar surface, and a distance from the planar surface to a nearest portion of the exhaust opening is no greater than 1.5 times a perimeter of the exhaust opening. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the outer housing has a perimeter less than three times the perimeter total cross sectional area of a connection of a direct vent system to which it is connected. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the inner pipe and outer housing comprise concentric cylindrical pipes, the inner pipe having a smaller diameter than the outer housing, and wherein the throttle cover comprises a cylindrical ring on the outer pipe. 
     Embodiments of the technology include any of the aforementioned embodiments comprising a direct vent termination for a vent system, the vent system having an exhaust section and an air intake section coupled to the termination. In these embodiments, the termination comprises a cylindrical inner pipe and a cylindrical concentric outer pipe surrounding the inner pipe to form a void between the inner pipe and the outer housing, the void adapted to provide intake are to the air intake section of the vent system; an end cap at a first end of the outer pipe, the inner pipe passing through the end cap and having an exhaust opening therein; an intake region formed in the outer pipe providing access to the void; and a throttle cover configured to be movably positioned and thereafter secured at one of a number of positions over the intake region using a throttle guide to thereby regulate air flow into the void. 
     Embodiments of the technology include any of the aforementioned embodiments wherein a total unrestricted area of the intake region is at least 35% of a cross sectional area of the outer pipe. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the throttle cover is adjustable to occlude at least 10 percent of an area of the intake region. 
     Embodiments of the technology include any of the aforementioned embodiments wherein the termination is mounted on a planar surface, and a distance from the planar surface to a nearest portion of the exhaust opening is no greater than 1.5 times a perimeter of the exhaust opening. 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.