Patent Publication Number: US-7717702-B2

Title: Direct sidewall vent system

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to vent systems for fuel-burning appliances and, more particularly, to a direct vent system that communicates between an internal space, within which the appliance is located, and the external atmosphere, through a vertically extending sidewall. 
   2. Background Art 
   Fuel-burning appliances are commonly equipped with direct sidewall vent systems. Typically, concentric conduits communicate between the appliance and an external atmosphere generally in a horizontal direction through an outside, vertically extending sidewall. An inner conduit communicates combustion gases from the appliance to the external atmosphere. An annular passage between the inner conduit and a surrounding conduit communicates makeup air from the external atmosphere to the appliance. 
   Ideally, to optimize operation and efficiency of the fuel-burning appliance, air flow volume to, and pressure in, the appliance burner are maintained within specific ranges. Reduced air flow to the burner may cause sooting, which is detrimental to the appliance and also produces pollutants that are undesirably discharged to the atmosphere and potentially to against the interior and exterior of the building within which the appliance is located. 
   The type and location of the intake for makeup air and its relationship to the subjacent surface, combustion gas outlet, and wall upon which the vent system is mounted, are critical in the design of such systems to maintain adequate air flow. Myriad different makeup air intakes have been devised in the industry. It is known, for example, to provide a makeup air intake at one side, or opposite sides, of the conduits. Operation of certain of these systems may be adversely affected by atmospheric wind conditions. 
   Environmental winds may adversely affect other vent designs as well. High winds tend to block the discharge of combustion gas. A pressure buildup may result in the combustion chamber that slows down air flow to the burner. This may result in sooting, with the attendant disadvantages, noted above. 
   More commonly, the makeup air is drawn from a region at the bottom of the external portion of the vent system. These bottom located intakes have some of their own inherent disadvantages. 
   Commonly, those installing direct vent systems will locate the external portion of the vent system in close proximity to the ground, either at the behest of the building owner, for purposes of aesthetics, or for reasons dictated by the building geometry or convenience and ease of installation. Manufacturers of these vent systems typically will specify a minimum clearance between the external portion of the vent system and the subjacent ground. Even within these specifications, there are some inherent problems that are commonly encountered. 
   First of all, an accumulation of snow or debris may effectively reduce the clearance between the makeup air intake and the ground. The intake may be partially, or in a worse case altogether, blocked so that the required air flow does not occur at the combustion chamber. 
   Even if the clearance is within manufacturers&#39; specifications, there is also the possibility that atmospheric winds may interact with the ground and surrounding structures to produce undesired pressure buildup at the makeup air intake. 
   Further, the discharged gases, and potentially pollutants, entrained therein, may be redirected at the subjacent surface so as to be recirculated by being drawn back into the makeup air intake. At low mounting heights, the makeup air intake is also prone to picking up debris that may be elevated thereto by winds and/or the discharging combustion gases. This debris may be detrimentally recirculated to the appliance. 
   Heretofore, in the interest of facilitating installation, or addressing aesthetic concerns, building owners have mounted the external vent components in close proximity to the ground, which has caused them to have to contend with the above-mentioned problems associated with conventional vent systems; notably variations in efficiency of the appliance operation, temporary flame-outs, sooting, etc. The industry continues to seek out designs to address some or all of the above problems. 
   SUMMARY OF THE INVENTION 
   In one form, the invention is directed to a direct sidewall vent system between a fuel-burning appliance in a first space and an external atmosphere, through a wall between the first space and external atmosphere. The direct sidewall vent system has a wall assembly that defines a first passage for communicating combustion gas generated through operation of the fuel-burning appliance to a first outlet through which the combustion gas is communicated to the external atmosphere. The wall assembly further defines a second passage for communicating makeup air from the external atmosphere to the fuel-burning appliance in the first space. The direct sidewall vent system further has an external portion that is situated within the external atmosphere and at which the first outlet is located. The external portion of the direct sidewall vent system has a top, a bottom, and spaced sides. The external portion of the direct sidewall vent system has a first inlet within the external atmosphere through which makeup air from the external atmosphere is communicated to the second passage. The first inlet is situated to draw makeup air from the external atmosphere primarily from a location above the first outlet. 
   In one form, the wall assembly has a vent pipe that has a central axis and defines at least a part of the first passage. The first inlet is situated to draw makeup air from the external atmosphere primarily from a location above the central axis of the vent pipe. 
   In one form, the second passage has a central axis and the first inlet is situated to draw makeup air from the external atmosphere from a location above the central axis of the second passage. 
   In one form, the wall assembly has substantially concentric cylindrical walls between which at least a part of the second passage is defined. 
   The first inlet may be situated substantially fully above the central axis of the vent pipe and/or central axis of the second passage. 
   In one form, the wall assembly has a funnel-shaped portion that has a progressively decreasing cross-sectional area from an upstream end of the first passage towards a) a downstream end of the first passage and b) the first outlet through which combustion gas is jetted to the external atmosphere. 
   The funnel-shaped portion may be oriented to jet combustion gas in a direction angularly downwardly and away from the wall between the first space and external atmosphere. 
   In one form, the wall assembly comprises a shroud that defines the first inlet. 
   The first inlet may open downwardly. 
   In one form, the shroud has a funnel-shaped portion in which incoming makeup air is expanded. 
   In one form, the wall assembly defines a surface below the first inlet that is inclined upwardly towards the first inlet so as to deflect air directed at the wall between the first space and the external atmosphere towards the first inlet. 
   The first outlet may open downwardly. 
   A flow inducing mechanism may be provided for at least one of a) inducing flow of combustion gas through the first passage and b) inducing flow of makeup air through the second passage. 
   The direct sidewall vent system may be provided in combination with a fuel-burning appliance within a first space bounded by a wall through which the direct sidewall vent system extends. 
   The wall assembly may be made from stainless steel. 
   In one form, the wall assembly has a second pipe surrounding the vent pipe and between which at least a part of the second passageway is defined. The second pipe has a top and bottom and makeup air through the first inlet is introduced to the second passage primarily through the bottom of the second pipe. 
   The invention is further directed to a direct sidewall vent system between a fuel-burning appliance in a first space and an external atmosphere through a wall between the first space and external atmosphere. The direct sidewall vent system has a wall assembly that defines a first passage for communicating combustion gas generated through operation of the fuel-burning appliance to a first outlet through which the combustion gas is communicated to the external atmosphere. The wall assembly defines a second passage for communicating makeup air from the external atmosphere to the fuel-burning appliance in the first space. The direct sidewall vent system has an external portion that is situated within the external atmosphere and at which the first outlet is located. The external portion of the direct sidewall vent system has a top, a bottom, and spaced sides. The external portion of the direct sidewall vent system has a first inlet within the external atmosphere through which makeup air from the external atmosphere is communicated to the second passage. The first inlet is situated to draw makeup air from the external atmosphere primarily from a location at the top of the external portion of the direct sidewall vent system. 
   The invention is further directed to a method of venting a fuel-burning appliance in a first space through a vertical sidewall between the first space and an external atmosphere. The method includes the steps of: providing a vent system having a wall assembly that defines first and second passages with one of the first and second passages having a central axis that extends through the vertical sidewall; operating the fuel-burning appliance and thereby producing combustion gas; causing the combustion gas to be directed through the first passage and discharge through a first outlet to the external atmosphere; and causing makeup air to be directed from the external atmosphere through an inlet that is in communication with the second passage and from the inlet primarily downwardly towards the cental axis of the one of the first and second passages for delivery through the second passage to the fuel-burning appliance. 
   The invention is further directed to a method of venting a fuel-burning appliance in a first space through a vertical sidewall between the first space and an external atmosphere. The method includes the steps of: providing a vent system having a wall assembly that defines first and second passages with one of the first and second passages having a central axis that extends through the vertical sidewall; providing a vent system having a wall assembly that defines first and second passages, with one of the first and second passages having a central axis that extends through the vertical sidewall, and that has an external portion exposed to the external atmosphere and having a top, bottom, and spaced sides; causing the combustion gas to be directed through the first passage and discharge through a first outlet to the external atmosphere; and causing makeup air to be directed from the external atmosphere through an inlet primarily at the top of the external portion of the vent system for communication through the second passage to the fuel-burning appliance. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic representation of a direct sidewall vent system, according to the present invention, operatively assembled through a vertically extending sidewall to communicate between a fuel-burning appliance and the external atmosphere through the sidewall; 
       FIG. 2  is a view as in  FIG. 1  wherein further detail of the vent system is shown in schematic form; 
       FIG. 3  is an exploded, perspective view of one specific exemplary form of the vent system in  FIGS. 1 and 2 ; 
       FIG. 4  is a side elevation of the vent system in  FIG. 3 ; and 
       FIG. 5  is a perspective view of the vent system in  FIGS. 3 and 4 . 
   

   DETAILED DESCRIPTION OF THE DRAWINGS 
   In  FIGS. 1 and 2 , a direct, sidewall vent system, according to the present invention, is shown schematically at  10  in association with a fuel-burning appliance  12 . The fuel-burning appliance  12  is not limited in nature and is shown schematically to encompass any appliance that operates through combustion of a fuel and requires discharge of combustion gases. The fuel-burning appliance  12  is provided within a space  14 , typically a room of a building, separated from the external atmosphere  16  by a vertically extending sidewall  18 . 
   The vent system  10  has a wall assembly, described in detail below, that defines a first passage  20  for communicating combustion gas generated through operation of the fuel-burning appliance  12  to an external combustion gas outlet  22 , through which the combustion gas is communicated to the external atmosphere  16 . The wall assembly further defines a second passage  24  for communicating makeup air from the external atmosphere  16  to the fuel-burning appliance  12  in the space  14 . An external portion of the vent system  10  has a makeup air inlet  26  within the external atmosphere  16  through which makeup air from the external atmosphere  16  is communicated to the second passage  24 . The external portion of the vent system  10  additionally defines the combustion gas outlet  22  and is secured at an external surface  28  of the sidewall  18  through an appropriate mount  30 . 
   The fuel-burning appliance  12  may have a blower  32  that directs combustion gas from the fuel-burning appliance  12  through the first passage  20  to and through the combustion gas outlet  22  to the external atmosphere  16 . Makeup air from the external atmosphere  16  is drawn in through the makeup air inlet  26  and conveys to and through the second passage  24  to the fuel-burning appliance  12 . An optional flow inducing mechanism  34  may be provided at an internal or external location to pressurize makeup air moving in the second passage  24  back to the fuel-burning appliance  12 . However, the present invention makes possible an adequate flow of makeup air to the fuel-burning appliance  12  without such a mechanical assist requirement. 
   The vent system  10  is shown schematically at  10  in  FIGS. 1 and 2  to encompass virtually unlimited different configurations of wall structure. Regardless of the configuration, the invention contemplates that the makeup air inlet  26  draws makeup air from the external atmosphere  16  primarily from an upper location on the external portion of the vent system  10 , preferably above the combustion gas outlet  22 . Details of one exemplary configuration for the vent system  10  will now be described with respect to  FIGS. 3-5 , with it being understood that this particular configuration is exemplary in nature only. 
   The aforementioned wall assembly is shown on the vent system  10  at  36 . The wall assembly  36  consists of a vent pipe  38 , with a central axis  40 , that defines a part of the first passage  20  between the blower  32  on the fuel-burning appliance  12  and the combustion gas outlet  22  on the external portion  42  of the vent system  10 . A downstream end  44  of the vent pipe  38  is suitably secured within an opening  46  defined in a flat plate  48 . 
   A wall  50  is cantilevered outwardly from the plate  48  and defines a flat surface  52  that slopes downwardly from the bottom of the opening  46 . A shroud  54  has a wall  56  with an open bottom  58  and an open end  60 . With the end  60  placed against the flat plate  48 , the opening  46  and wall  50  reside within a chamber  62  bounded cooperatively by the wall  56  and flat plate  48 . 
   With the shroud  54  secured to the flat plate  48 , a sloping portion  64  of the shroud wall  56 , spaced side portions  66 ,  68  on the shroud wall  56 , and the wall  50  projecting from the flat plate  58 , cooperatively define a funnel-shape portion of the wall assembly  36  that causes discharging combustion gas to be jetted generally in the direction of the arrow  70  in  FIG. 4  to the external atmosphere  16 , downwardly and away from the sidewall  18  upon which the vent system  10  is mounted. As seen in  FIG. 4 , the sloping portion  64  of the shroud wall  56  has an inside surface  72  that faces the surface  52  on the wall  50  and bounds a portion of the first passage  20  within the funnel-shaped portion of the wall assembly  36 . The surface  52  is at an angle θ to horizontal, with the surface  72  at an angle θ 1  to horizontal, with θ 1  being greater than θ. The angles θ, θ 1  may be on the order of 45°, but could vary considerably from 45°. Accordingly, the cross-sectional area of the portion of the first passage  20  within the shroud  54  progressively decreases towards the downstream end of the first passage  20  and the outlet  22 . Through this arrangement, the aforementioned jetting action is produced that propels the combustion gases away from the sidewall  18  to prevent exposure of the gases to the sidewall  18  as might leave unsightly residue thereon. This jetting action also reduces the tendency of the combustion gases to recirculate into the second passage  24  through the makeup air inlet  26 , as described in greater detail hereinbelow. The flat plate  48  projects to below the outlet  22  to deflect discharging combustion gases and shield the wall  18  from exposure thereto. 
   A hood  74 , having the same general configuration as the shroud  54 , but larger in dimension, is mounted against the flat plate  48  so that the shroud  54  resides substantially fully within a chamber  76  bounded by the hood  74 . In addition to other functions, described below, the hood  74  shields the user from the surfaces on the shroud  54  that become heated in use. 
   The shroud  54  and hood  74  are provided with peripheral flanges  78 ,  80 , respectively, which are suitably secured to the flat plate  48 , as by separate fasteners, welding, or the like. 
   A second pipe  82 , with a diameter larger than the diameter of the vent pipe  38 , surrounds the vent pipe  38  to be in concentric relationship therewith so that an annular space  84  is defined between the pipes  38 ,  82 . The annular space  84  defines part of the second passage  24  for communicating makeup air from the external atmosphere  16 , drawn in at the inlet  26 , to the fuel-burning appliance  12 . A flanged, upstream end  86  of the second pipe  82  is secured suitably to a side  88  of the flat plate  48  facing oppositely to the direction faced by the surface  89  to which the shroud  54  and hood  74  are mounted. 
   A spacing frame at  90  is mounted to a flat plate  92  having the same, generally squared shape as shown for the flat plate  48 . The flat plate  92  defines part of the mount  30 , through which the vent system is secured to the sidewall  18 . The spacing frame  90  consists of contiguous bottom and spaced side frame parts  94  and  96 ,  98 , respectively. The frame parts  94 ,  96 ,  98  have the same width dimension W and are flanged to facilitate their attachment to the flat plates  48 ,  92 , by any suitable means, so that the frame parts  94 ,  96 ,  98  maintain the flat plates  48 ,  92  together and spaced apart a distance equal to the width W. 
   A shroud  100  is attached through at least one flange  102  to the flat plate  92  and resides between the frame parts  96 ,  98 . The shroud  100  and frame parts  94 ,  96 ,  98  cooperatively extend continuously around a chamber  104  between the flat plates  48 ,  92 . The shroud  100  extends further from the flat plate  92  than the frame parts  94 ,  96 ,  98 , with the additional extension having an inclined wall portion  106  that vertically overlies on inclined outer surface  108  of the hood  74  in vertically spaced relationship thereto. The inside surface  110  of the wall portion  106  of the shroud  100 , and facing hood surface  108 , may be substantially parallel or may converge in a downstream direction over a portion of the second passage  24  defined by these surfaces. The surface  108  axially coincides with the central axis of the vent pine  38  and, as depicted, blocks flow of air in an axial direction directly into the first passage  20 . With the shroud  100  projecting, as seen most clearly in  FIG. 4 , the shroud  100  acts as an air scoop for funnelling atmospheric air through the inlet  26  into the passage  24 . The angles of the surfaces  108 ,  110  may be on the order of 45°. However, these angles might vary considerably from 45°. 
   In windy conditions, air moving in the direction of the arrows  112  encounters the hood surface  108  and is progressively bent upwardly to move into the inlet  26  and is thereafter funneled into the chamber  104  wherein it expands. The air in the chamber  104  communicates radially through a series of openings  112  through the second pipe  82  and into the annular space  84  for delivery back to the fuel-burning appliance  12 . The openings  112  are shown as circular with an exemplary diameter on the order of one inch. The openings  112  could have different sizes, shapes, and locations around the periphery of the pipe  82 . One or more larger holes could be utilized in place of the openings  112  shown. 
   With this arrangement, substantially the entirety of the makeup air delivered to the fuel-burning appliance  12  through the second passage  24  is drawn from the external atmosphere  16  through the makeup air inlet  26  in the region at the top of the external portion  42  of the vent system  10  above the combustion gas outlet  22 . The locations of the inlet  26  and outlet  22  are not limited to precisely what is shown in  FIGS. 3-5 . Preferably, the makeup air is drawn from the external atmosphere from a location located above the central axis  40  for one of the passages  20 ,  24 . In this case, the central axes for the passages  20 ,  24  are coincident. 
   As seen in  FIGS. 3-5 , the makeup air inlet  26  is situated fully above the central axis  40 . It is preferred that if not located entirely above the central axis, the makeup air inlet  26  be located so that substantially the entirety of the makeup air delivered to the fuel-burning appliance through the second passage  24  is drawn from the external atmosphere  16  primarily from a location above the central axis  40 . As shown, and most preferably, the makeup air is drawn primarily from a location at the top of the external portion  42  of the vent system  10 . 
   In operation, as the fuel-burning appliance  12  is operated, combustion gas is produced. Through the blower  32 , and/or by reason of a temperature differential, the combustion gas is caused to be directed through the first passage  20 , and more particularly initially through the vent pipe  38 , through the shroud  54  and to and through the outlet  22 . 
   The makeup air enters the downwardly opening inlet  26  and expands into the chamber  104  from where it communicates through the openings  112  into and through the annular space  84  to the fuel-burning appliance  12 . 
   By reason of the top location of the makeup air inlet  26 , and the jetting of the combustion gas from the outlet  22 , there is potentially little recirculation of the combustion gas as makeup air. The bottom frame part  94  has a series of slots/openings  114  therethrough which allow drainage of any accumulated condensation and also provide an escape route for other foreign matter that may have migrated into the chamber  104 . With the pipe openings  112  located at the bottom region of the pipe  82 , any foreign matter that enters the chamber  104 , as via the shroud, may drop against the periphery of the pipe  82 . By reason of there not being openings in the top region of the pipe  82 , this matter tends to slide guidingly down the pipe to against the bottom frame part  94  from where it may discharge through the slits/openings  114 . Of course, the invention contemplates that openings through the pipe  82  may be provided at any peripheral location thereon. However, such a design would generally be more prone to causing entrainment of foreign matter into the makeup air supply communicated to the fuel-burning appliance  12 . 
   In calm environmental conditions, system designs are normally such that the makeup air is drawn into the fuel-burning appliance  12  in adequate volume. Under windy conditions, the wind load tends to produce a pressure block at the outlet  22 . As a result, a burner on the fuel-burning appliance  12  may be unable to achieve complete combustion whereupon sooting may occur. Under these windy conditions, the inventive design causes the impinging air to be funneled under pressure into the inlet  26  and through the second passage  24  to the fuel-burning appliance  12 . With the pressurized makeup air, cleaner combustion in the fuel-burning appliance  12  may result. 
   Accordingly, with the described design, the external portion  42  of the vent system  10  can be placed in close proximity to the subjacent ground at the sidewall  18  and may, at this lower height, still be capable of drawing in adequate volumes of clean makeup air without substantial fear of flame-out of the burner or sooting commonly encountered with significant intake losses. This facilitates installation by allowing installers to work at comfortable heights. Fewer installation problems and errors may result. This also places the external portion  42  of the vent system  10  below normal sight lines. 
   For purposes of integrity, and resistance to corrosion, the components of the wall assembly  36 , and particularly those that are exposed to the combustion gases and the elements in the external atmosphere  16 , may be made from stainless steel. 
   An optional third pipe  116 , as shown in  FIG. 4 , may reside between the vent and second pipes  38 ,  82 , respectively, in concentric relationship therewith. Through this arrangement, an annular space  118  is defined between the pipes  38 ,  82 . The space  118  performs an insulating function to minimize heat exchange in the event there are significant temperature differentials between the departing combustion gases and the incoming makeup air from the external atmosphere  16 . 
   It is also contemplated that the vent pipe  38  can be made as a single piece. Prior systems generally use a short stub pipe in the installation process. By using a single pipe construction, the likelihood of a leak into and from the first passage  20  is minimized. 
   High temperature silicone RTV sealant may be used at critical connections, such as between the downstream end  44  of the vent pipe  38  and the flat plate  48 . This minimizes the likelihood of recirculation at this and other locations. The use of a flange  120  on the downstream end  44  of the vent pipe  38  may further facilitate maintenance of the integrity of the connection of the vent pipe  38  and flat plate  48 . 
   The foregoing disclosure of specific embodiments is intended to be illustrative of the broad concepts comprehended by the invention.