US3410193A - Recessed vent assembly for sealed combustion wall furnace - Google Patents

Description

Nov. 12, 1968 D. 1.. CLARK 3,410,193-

RECESSED VENT ASSEMBLY FOR SEALED COMBUSTION WALL FURNACE Filed April 26, 1967 FIG! v I R: P 'o T DALE L. CLARK ATT'YS United States Patent 3,410,193 RECESSED VENT ASSEMBLY FOR SEALED COMBUSTION WALL FURNACE Dale L. Clark, Wichita, Kans., assignor to The Coleman Company, Inc., Wichita, Kans., a corporation of Kansas Filed Apr. 26, 1967, Ser. No. 633,938 Claims. (Cl. 98-32) ABSTRACT OF THE DISCLOSURE A wall ventilation assembly for a natural draft, sealed combustion furnace. The fresh air intake and combustion air outlet are recessed in the wall with the mouth of the fresh air intake passage being set back further than the mouth of the combustion air outlet. The recessing of the vent assembly cooperates with a baflie structure to establish an air flow pattern substantially independent of the impact angle of wind gusts by directing such wind behind the combustion air outlet and into the fresh air intake while permitting combustion products to exhaust. The vent and baflle assembly are further designed to eliminate hot spots caused by exhaust gases and to prevent rain from entering the fiues.

Background The present invention relates to a ventilation system; and more particularly, to a wall ventilation system for a natural draft, combustion furnace. There have been many attempts to provide adequate combustion air ventilation for sealed, natural draft furnaces. A diificult problem is presented when it is desired to vent the combustion air system through a vertical wall.

Heretofore, developments of wall vent systems for sea-led combustion furnaces have centered about one of two separate approaches. The first approach is to provide two separate passages though the wall, one for the fresh air intake and the other for the exhaust air outlet. Typically, the exhaust air outlet is spaced above the fresh air intake so that the heated exhaust gases will rise thereby preventing a mixture of exhaust air with the fresh air. This approach obviously increases installation and maintenance cost by requiring two passages to be cut in the wall.

A second and more desirable wall ventilation system is one wherein the exhaust and inlet fiues are coaxial. The exhaust gases run through the center flue and the fresh air is taken in through the annular conduit surrounding the exhaust flue. This system requires that only one passage be cut through the wall but at the same time, because wind drafts or gusts may be expected from any direction, there is a possibility of routing the exhaust gases to the fresh air intake. A second disadvantage of these latter systems is the possibility of creating a back draft in the exhaust flue thereby reducing the efliciency of the system, or of creating an area of stagnant air about the mouth of the exhaust flue which, if it persisted long enough, could extinguish the flame or pilot light in the furnace. Further, any permanent area of stagnant air above or about the exhaust flue will cause a hot spot in the ventilation system which may be a fire hazard.

Existing ventilation systems for concentric intake and exhaust conduits include simply extending the mouth of the exhaust flue to a distance spaced further from the exterior surface of the wall than is the mouth of the intake flue. A mushroom-shaped skirt then depends from the mouth of the exhaust flue toward the exterior surface of the wall to aid in separating combustion products and fresh air. A cap is placed over the mouth of the exhaust flue allowing the exhaust gases to escape radially while ice preventing rain from entering the exhaust flue. Such systems are inadequate in that they are dependent upon the impact direction of wind. A head-on wind will cause the exhaust gases to be routed back to the fresh air intake conduit, whereas down drafts will ordinarily reverse the natural air flow pattern for both the intake and exhaust gases.

Other attempts to provide an adequate ventilation system for concentric flues through a vertical wall have depended upon establishing an exhaust flow pattern which is generally upward and a similar intake pattern with the fresh air being drawn in only at the bottom of the intake flue. In such systems, dead air spaces are created at the top of the intake flue and hot spots result in these spaces. Further, these systems are sensitive to down drafts which will reverse the flow pattern of the exhaust gases.

There have been numerous other attempts to separate fresh air intake and exhaust gases while rendering the ventilation system relatively independent of wind direction, and the operability of most of the systems depends upon the fact that a major velocity component of incident wind will be horizontal. This is usually the case for a house or other stationary building. However, if the wall through which the ventilation system passes is that of a house trailer or the like, there may be substantial up and down drafts which would not otherwise be significant.

Summary The present invention eliminates the aforementioned disadvantages of ventilation assemblies adapted for use with concentric fiues for fresh air intake and combustion air outlet by providing a vent which establishes a normal air flow pattern such that the heated combustion air flows upward exhausting at the top, and the fresh air is taken in at the bottom under all wind or draft conditions. This insures that there will be no back drafts in the circulating system or other interference with the natural draft of the system such air stagnation at the exhaust outlet, as has occurred in some prior ventilation systems. This is accomplished by recessing the mouths of the fresh air intake and exhaust outlet fiues into the wall through which they are fed and by providing a unique baflling structure for insuring a continuous flow pattern.

Hot spots are eliminated throughout the ventilation system by structuring the surfaces defining the natural air flow pattern to be free from crevices or stagnation areas. Further, the natural air flow pattern that is developed is continuous and it establishes the continuous flow of fresh air for cooling surfaces in the vent immediately adjacent the wall in which the vent is recessed.

Installation of the vent is facilitated by providing a twopiece assembly, one of which, called the vent back assembly, couples to the fresh air intake conduit and is secured to the exterior wall; the other is referred to as the baffle assembly, and it couples to the exhaust outlet and is fastened to the vent back assembly.

A further advantage of the instant invention, particularly when it is installed with the ventilation system on a house trailer, is that there are no protruding elements or members beyond the peripheral mounting flange of the vent thereby providing a vent which is substantially flush with the exterior surface of the wall through which the intake and exhaust fiues are fed.

Other advantages and features of the instant invention will be obvious to persons skilled in the art from the following detailed description of a preferred embodiment accompanied by the attached drawing in which identical reference numerals will refer to like elements in the various views.

The drawing FIG. 1 is a partly broken away front elevational view of a vent according to the instant invention;

FIG. 2 is a side sectional view taken through the line 22 of FIG. 1; and

FIG. 3 is a rear elevational view of the vent of FIG. 1.

Detailed description As previously mentioned, the present invention is particularly suited for use with a ventilation system wherein both the fresh air intake and the combustion air outlet are fed through a common aperture formed in a wall of a house trailer. In FIG. 1, reference numeral generally signifies the exterior wall of a space being heated and through which the fresh air intake and exhaust air outlet conduits are formed. As shown in phantom in FIG. 2, the arrangement of intake and exhaust conduits comprises a first cylindrical tube 11 defining the exhaust flue, a slightly larger cylindrical insulator tube 12 coaxial with the exhaust flue 11, and a still larger tube 13 which is also coaxial with the exhaust flue 11.

The annular space between the exhaust flue 11 and the intermediate tube 12 defines a dead air space which provides insulation between the heated exhaust gases and the fresh air intake gases which are drawn through the annular space between the intermediate tube 12 and the outer tube 13.

This arrangement of a central exhaust conduit for the heated combustion gases, a first annular insulating space about the exhaust conduit and a second annular intake conduit about the insulating section performs a number of functions.

The most important function is that it provides a very good isolation between the heated exhaust gases and the wall through which the ventilation conduits are fed. It is noted that the cooler fresh air contacts the exterior conduit 13 which engages the wall 10 thereby minimizing heating of the wall. Secondly, the annular insulating region of trapped air reduced the heat transfer from the exhaust flue to the fresh air being drawn in. This is important since the efliciency of combustion is a function of the temperature difference between the intake and flue products and depends upon a continuous supply of fresh intake air.

In describing the preferred embodiment of the vent, the manner of installing it will be better understood if the description is divided into the two parts corresponding with the two sub-assemblies comprising the complete vent. For this purpose, the vent assemblies will hereinafter be referred to as the vent back assembly which provides the couples directly to the exhaust flue 11 and provides baffling for establishing the air flow pattern for both intake and exhaust gases.

Vent back assembly The vent back assembly comprises generally an open rectilinear or box-shaped receptacle including a back plate 14, a top 15, side members 16 and 17, and a bottom 18. The top is formed behind the back plate 14 and riveted thereto as at 19. The top 15 defines a front flange for mounting to the exterior surface of the wall 10. Apertures 21 receive sheet metal screws (not shown) in mounting the vent back assembly to the wall 10.

Similarly, the receptacle sides 16 and 17 as well as the; bottom 18 are attached to the back plate 14 by riveting, and they define front peripheral flanges for mounting the vent back assembly to the wall 10.

The back plate 14 is provided with an aperture 22, seen most clearly in FIG. 3, through which is received a collar 23. At its base, the collar 23 includes a peri heral flange 24 which is welded to the back plate 14, and the 4 neck of the collar 23 defines a decreasing circumference when proceeding away from the back plate 14 in the direction of fresh air intake for sliding into the tube 13. It will be noted that the center of the aperture 22 is offset below the horizontal center line of the back plate 14.

A top deflector plate 25 extends substantially the entire width of the back plate 14 and extends from the front of the receptacle top 15 rearward and downward toward the back plate 14 which it engages at an angle of about 45 with the vertical. The upper deflector plate 25 has 21 depending flange 26 extending upwardly in front of the front peripheral flange of the receptacle top 15, and the two are riveted together as at 27.

The upper deflector plate 25, the receptacle top 15 and the back plate 14 define a region of trapped air having a triangular cross section providing additional heat insulation for the wall 10. It will be obvious from subsequent description that the hot exhaust gases do not contact the upper deflector plate 25 over any substantial portion of its face, nor are they allowed to be trapped in any recesses which would form a hot spot.

A lower deflector plate 28 is provided at the bottom of the receptacle, and it includes a front flange which is riveted to the front peripheral flange of the receptacle bottom 18, as indicated at 29. The lower deflector plate 28 extends rearwardly and upwardly from the surface of the wall 10; and, at its rear-most location, it engages the back plate 14 at a vertical location which is approximately the same as the lowermost edge of the collar 23, which defines the mouth of the fresh air intake conduit.

A vertical deflector plate 30 is riveted to the bottom deflector plate 28 and extends upwardly therefrom at its center. The plane of the vertical deflector plate 30 passes through the axis of the exhaust flue 11, and the uppermost edge of the vertical deflector plate 30 is located slightly above the lower periphery of the collar 23, as best seen in FIG. 2. As will be described in more detail below, the function of the vertical deflector plate 30 is to divert air into the fresh air intake conduit when the wind velocity is horizontal and along the exterior surface of the wall 10.

Having thus described the vent back assembly as a unitary structure, it will be appreciated that this assembly is easily installed within a recess provided in the wall 10 by simply inserting the innermost and smallest taper of the collar 23 within the fresh air intake conduit and attaching the outer peripheral flange of the receptacle to the wall 10 with sheet metal screws in the apertures provided in its peripheral flange.

Vent baflie assembly The vent baffle assembly includes first and second side plates, identified respectively by reference numerals 31 and 32, respectively spaced inwardly from and parallel to sides 16 and'17 of the vent back assembly when assembled. Each of the side plates 31 and 32 includes, at its rear edge, an outwardly flaring lip, identified respectively as 33 and 34 in FIG. 1, for receiving sheet metal screws 35 in attaching the baflie assembly to the vent back assembly after the back assembly has been installed in the recess of the wall 10, as previously described.

Each of the side plates 31 and 32 is further defined by an inclined upper edge which extends upwardly and outwardly from the back plate 14 of the receptacle, defining an edge substantially parallel to the upper deflector plate 25 and lying beneath it.

A baflle top plate 36 is attached to the upper edges of the side plates 31 and 32; and it is located in a plane parallel to the plane of the upper deflector plate 25, as seen in FIG. 2. The baffle top 36 extends from the back plate 14 of the receptacle upwardly and forwardly substantially the depth of the receptacle.

A rectangular face plate 37, the center of which has been cut away in FIG. 1, is attached to the baffle side plates 31 and 32; and it is located approximately in the vertical plane defined by the peripheral mounting flanges of the vent back assembly, that is, in the plane of the exterior surface of the wall 10. The lower horizontal edge of the face plate 37 is approximately in the same horizontal plane as the lower edge of the fresh air intake collar 23. The upper edge of the face plate 37 is located slightly below the horizontal plane which includes the lower edge of the baflle top 36.

A baflle back plate 38 is located in the vertical plane between the face plate 37 and the back plate 14 of the vent back assembly when the baffle assembly is mounted thereon. The baflle back plate 38 is attached to and supported by the baflie side plates 31 and 32. An exhaust collar 39 is attached to an aperture on the baflle back plate 38, the center of which lies along the axis of the exhaust flue 11. As best seen in FIG. 2, an expanded portion of the collar 39 receives the exhaust flue 11, and the collar 39 then defines a slightly reduced portion 40 which is attached to the bafile back plate 38. The top of the back baflle plate 38 is located in a horizontal plane with the top of the baflle face plate 37; and the bottom the bafile back plate 38 is in line with the bottom of the batfle side plates 31 and 32 which terminate slightly above the top of the vertical deflector plate 30. It will be noted from FIG. 2 that the intermediate insulator tube 12 abuts the baflle back plate 38 in assembled position to define the annular region of trapped air.

Spacer tabs 40a are welded to the exterior surface of the restricted portion 40 of the flue outlet coupling collar 39 to maintain the intermediate tube 12 at constant spacing from the exhaust flue.

The vent baflie assembly is also provided with a top rain shield 41 which is located slightly beneath the baffle top 36 and lies parallel to it, as best seen in FIG. 2. The top rain shield 41 is attached at its sides to the baflle sides 31 and 32, and it extends depthwise of the baflle assembly from a point directly beneath the leading edge of the baflie top 36 to a point just behind the baflle back plate 38. The top rain shield 41 serves two very important functions, as will be made clear presently from a discussion of the operation of the vent.

A front rain shield 42 is located in a vertical plane between the baflle face plate 37 and the baflle back plate 38; and its upper edge is in horizontal line with the upper edge of the batfle face plate 37. The vertical rain shield 42 has a lower edge which is located above the upper edge of the collar 39 which couples to the exhaust flue 11.

Operation Having thus described in detail a preferred vent back assembly and vent bafile assembly, the installation of the same to an existing flue system will be obvious. There will now be described in detail the normal air flow pattern and the effect upon it of winds having various impact angles. The relative spacing and proportions of the various element's comprising the two assemblies will be obvious from the drawing together with the above detailed description, but additional information may be obtained from the following functional description of each of the various elements.

Under normal conditions, that is when there is no appreciable external wind, fresh air will be drawn in beneath the bottom of the baflle face plate 37 behind the baffle back :plate 38 and into the annular intake conduit between the intermediate insulator tube 12 and the outer tube 13, passing through the coupling collar 23. Some of the intake air will contact the intermediate tube 12 and be slightly heated and rise in a vertical channel between the back plate 14 of the vent back assembly and the baffle back plate 38. This air, which is much less hot than the exhaust gases, will be routed between the battle top 36 and the upper rain =baflie 41 Where it will mix with and cool the hotter exhaust gases.

The exhaust gases will exit at the mouth of the contracted portion 40 of the collar 39 and rise between the baflle back plate 38 and the baffle face plate 37 until it contacts the upper rain shield 41 at which point it will be directed outward away from the wall 10.

Although there will obviously be some heating of the wall 10, it will be noted thatthere is no trapping of any of the hot gases since the space 27a is a closed space and provides insulation for the top 15 and the upper portion of the back plate 14. In addition, as noted above, some fresh air will have been routed between the baflle top 36 and the upper rain shield 41 to mix with the heated exhaust gases. Further, air is allowed to circulate between the vertical sides of the baflle assembly and the vertical sides of the back assembly and in the region between the baffle top 36 and the upper deflector plate 25. It will also be noted that there will be some fresh air drawn up directly behind the baflle face plate 37 to mix with the exhaust gases as soon as they exit from the collar 39 The fact that the mouths of the fresh air intake conduit and the exhaust flue have been recessed within the exterior surface of the wall 10 contributes greatly toward neutralizing any wind velocity components parallel to the exterior surface of the wall. The batfle face plate 37 and side plates 31 and 32 cooperate to effectively neutralize horizontal wind velocity components, and they further serve as a rain and debris shield. The lower rain shield 42 serves to collect rain falling inward of the vent assembly and to route it downward to the lower deflector plate 28.

It will also the noted that due to the fact that the lowermost edge of the upper rain baffle 41 terminates above and behind the upper edge of the baflle back plate 38, a horizontal wind will be deflected downward behind the baffle back plate 38 toward the fresh air intake and not toward the mouth of the exhaust outlet. This advantageously insures against back drafts in the exhaust system or against stagnating the exhaust air to a point where the pilot light would be extinguished. Further, the lower deflector plate 28 directs a horizontal wind upward directly into the fresh air intake conduit, while the upper deflector plate 25 will direct the same wind downward about the sides of the baflle assembly. Thus back drafts in the ex haust system are effectively prevented under all Wind conditions.

If the wind 'has a horizontal velocity component which is parallel to the exterior surface of the wall 10, the vertical deflector plate 30 will intercept such a wind as it is routed into the recess to force some of the wind directly into the 'fresh air intake and also upward to mix with the exhaust gases.

Having thus described in detail a preferred embodiment of a vent back assembly and a vent baflle assembly according to the present invention together with the function and operation of the structural elements of each, it will be obvious to :persons skilled in the art that equivalent structure may be substituted for that which has been described while continuing to practice the principle of my invention; and it is therefore intended that all such modifications and substitutions be covered as they are embraced 'within the spirit and scope of the appended claims.

I claim:

1. A vent assembly for coupling with an exhaust flue and a fresh air intake conduit formed in an annular region about the exhaust flue, said exhaust flue and fresh air intake conduit communicating through a vertical wall confining a space to be heated, comprising: means defining a recess in said wall, said recess communicating with said intake conduit and said exhaust flue; receptacle means adapted to be mounted in said recess and including means for coupling with said fresh air intake conduit; and baflle means adapted to be mounted to said receptacle means, said baflle means including exhaust coupling means for coupling to said exhaust flue, means coupled to said exhaust coupling means defining a substantially vertical conduit open at top and bottom for receiving heated exhaust gases, inclined baflle plate mounted above said vertical exhaust channel for directing said heated exhaust gases out of said recess, means defining a substantially vertical fresh air channel interior of said exhaust channel and communicating with said fresh air intake conduit, said fresh air channel being open at top and bottom, a second baflle plate inclined and substantially parallel with said first baflle plate and cooperating therewith to define an open channel above said fresh air channel for receiving vertically-moving fresh air and mixing it with said heated exhaust gases directed away from said recess, said first inclined baffle plate defining an edge located above said vertical fresh air channel whereby heated exhaust gases will be directed out of said recess and incident winds will be directed into said vertical fresh air channel thereby preventing back drafts in said exhaust flue.

2. A vent assembly adapted to be mounted within a vertical wall confining a space to be heated and coupling with an exhaust flue communicating through said wall and a fresh air intake conduit formed in an annular region about said exhaust flue, comprising: a receptacle to be mounted within said wall and including a verticallyextending backplate providing means for coupling with said fresh air intake conduit, said exhaust flue extending through said backplate and defining a discharge mouth in said receptacle; a baffle plate vertically mounted within said receptacle in spaced relation with said backplate and extending radially of the mouth of said exhaust flue to a location above an extension of said intake conduit; a vertical faceplate in front of said baifle plate overlying the mouth of said exhaust flue in outwardly-spaced relation thereto; and first and second sideplates extending respectively between said bafile plate and said faceplate on either side thereof and spaced inwardly of the sides of said receptacle thereby to define with said baffle plate and said faceplate a substantially vertical conduit within said receptacle for receiving gases from said exhaust flue and guiding the same above said intake conduit.

3. The structure of claim 2 wherein said receptacle is box shaped with an open front and has top, bottom and first and second side walls integral with said backplate and wherein said faceplate lies approximately in the plane of the exterior surface of said wall.

4. The structure of claim 3 further comprising a first deflector plate attached to said receptacle and inclined downwardly and outwardly from the lower periphery of said fresh air intake conduit for routing wind having a velocity component normal to the exterior surface of said wall into said fresh air intake conduit beneath said bafile late. p 5. The structure of claim 4 further comprising a vertical vane mounted on said first deflector plate and extending upwardly therefrom in a plane approximately in the vertical plane of the axis of said annular intake conduit for routing wind having a horizontal velocity component parallel to said exterior surface of said wall into said fresh air intake conduit.

6. The structure of claim 5 further comprising a first upper deflector plate attached to said receptacle and extending upwardly and outwardly of said backplate from a location above said intake conduit, said first upper deflector plate extending the width of said receptacle for preventing the accumulation of heated exhaust gases in the upper corner thereof.

7. The structure of claim 6 further comprising a second upper deflector plate mounted between said sideplates and beneath said first upper deflector plate and extending outwardly and upwardly from a location on said receptacle backplate above said intake conduit; and a third upper deflector plate mounted between said sideplates beneath said second upper deflector plate and extending upwardly and outwardly from a location adjacent the top of said baffle plate, whereby said second and third upper deflector plates define a channel for routing wind having a horizontal velocity component over the top of said baffle plate and into said fresh air intake conduit.

8. The structure of claim 2 wherein said first and second sideplates extend from said faceplate rearward of said baffle plate and are removably mounted to said receptacle backplate for providing a. unitary subassembly with said faceplate and said baflle plate.

9. The structure of claim 8 wherein said baffle plate and said faceplate extend from a position slightly beneath an extension of the lower extremity of said exhaust flue to a position substantially above an extension of the upper extremity of said annular intake conduit, whereby fresh air is routed beneath and behind said baffle plate into said intake conduit and exhaust gases are routed upward through said vertical exhaust channel.

10. The structure of claim 9 further comprising a rain batfle plate mounted to said first and second side plates intermediate said faceplate and said baflle plate and extending above an extension of the upper periphery of said exhaust flue.

References Cited UNITED STATES PATENTS 2,755,794 7/1956 Wendell 98-32 X 2,848,936 8/1958 Vallero 98-32 X 2,966,838 1/1961 Thompson et al. 2,998,764 9/1961 Bedell et al. 3,327,609 6/1967 Sage et al 9846 LLOYD L. KING, Primary Examiner.

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