US2741972A - Roof jack for ventilating duct - Google Patents

Description

April 17, 1956 R. PRYNE ROOF JACK FOR VENTILATING DUCT Filed Aug. 14, 1953 IIM JNVENTOR. RALPH PRyA/E, BY

, United States Patent RalphPryne, Pomona, Calif 'assignorto Pryne & (20., Inc., Pomona, Calif. ,'aicorporation of California Application August '14; 1953, .Serial No. 374,332

4"Claims. .(Cl.'9'8-'-11'9) The present invention relates generally to ventilating apparatus and equipment and relates more particularly to protective closure meansfor the open upper end of a ventilating .duct passing through a roof or the like. Protective closures of this type are commonly referred to in the trade as roof jacked-and will be so referred to herein, but it will be understood that the term is used without intending to limit the invention inany way.

Ventilating fans, or blowers may discharge air from residences and buildings through an exhaust duct which opens to the atmosphere. The open end of this .duct needs to-lbe' protected, not only against'the entry of winds and rain but also convection air .currents "which would create a back-draft or reverse flowintothe duct when the fan is not operating. .For this purpose, v.asuitably designed closure meansis provided on :the. roof-to receive and .cover the open end of .theaexhaustduct, this closure means including .a pivotally mounted shutter which can swing by, gravity to .a position closing the end ofathe duct and which can be .opened by the l-Pf6SSLIf6 .of air being discharged tothe-atmosphere.

.Because roofs .may .be flat or pitched .atany angle over .a considerable range .ofangles, and exhaust ducts of different sizes and shapes are 'found in actual practice, roof .jacks have been of different sizes and-shapes to fit different .sets of conditions. -Ability'to standardize ona single design .orsize which, even if not fullyruniversal, wilLfit anumber of-diflerent cond'itions, will result in :a cheaper, moresatisfactoryarticle. t

It is a general object of my invention to improve the effectiveness of .the-aoperation of closure :means of this type .at :the end of an exhaust duct. a It is .alsoa general-objectofmy invention toprovide a new and improved design [for a roof jack which adapts a vjack of .a single standardized sizetos-all roofs within the range of :slopes usually encountered, vas well as a flat roof, and :a-considerable 'varietyvof sizeszaofwexhaust ducts. 7. his also ;an object *of my invention to :provide .an improved design for a roof jack ain-which wind blowing into ?the outlet-op'eningis deflected to exert a force-on the shutter .tendingtto close lthe'shutter and thereby keep out the Wind. r p

It vis a further objectof :my invention to provide .an improved design for :a roof jack in which the aoutgoing stream of air is deflected smoothly :and continuously towards then-outlet of rthe jack so that :the :air :stream .flowsthrough the roof =jack'with atminimum:ofiiresistance.

The above objects are obtained .in :a closure mean's embodying rny'dnvention having a planar base :flange and wall means :rising upwardly from the flange around the sides of an inlet "opening defined byzthe2flange. The wall means includes a pair of parallel side :v'valls, a front wall that slopes upwardly and rearwardly, ,and a rear .wall that-slopes aupwardly and forwardly. Inside the .jack the walls define a throat of .materiallywlesser .area Qthan the .inletopening; .and .-a..shut ter is ,mounted at the throat to swing by gravity towards a normal closed 2 position. A portion of the rearv wall extends forwardly over the sloping'front wall and, together with portions of the sidewalls, forms a hood over the shutter and also defines a downwardly facing air outlet opening.

In a preferred embodiment, the shutter is mounted on a removable frame which ,is held in place at the throat by engagement with the various-walls of the closure means. This frame carries a baffle along its forward side toshield the forward edgelof'the shutter from air cur rents which might .tendto open it andblow'past the shutter.

How the above objects and advantages of my invention, as well as others not specifically referred to herein, are attained will be more readily understood by reference to the following description and to the annexed drawings, in which:

Fig. Us a. perspective viewof a roof jack embodying my invention;

Fig. 2 is an enlarged vertical section through my improved roof jack showing it'mounted on-a flat roof;

Fig. 3 is a fragmentaryhorizontal section on lin'e 3'3 of Fig. '2;

Fig. 4 is a fragmentarvsection on line 4-4 of Fig. 2; and 1 Fig. S'isaside elevation-atreduced scale showing the roof jack installed on a sloping roof.

.Referring now to the 1 drawings, there is shown in Fig. 1 a roof jack as it appears by itself; and itis shown installed on a flat roof in Fig. 2 or on a sloping roof inFig. 5. 'Theroofjack has 'aflator=planar flange -10 atits base by which the-jackis fastened to roof -12 in an ait-tight and Water-tight manner. Details of this connection to the roof are conventional and notpart of this invention, so are-not shown. Thejack is mounted on top oftheroof over the-open-upper'endof exhaust duct '14 which normally is running vertically 'wherexit passes through the roof. Air forcedthroughduct 1 4 by-a-famnot shown, isexhausted to the atmosphere after passing through the .roof jack. At the level of 'base flange :10 :is inlet opening 15 which is preferably-"rectangular,-typically beingsquare. The flange extends'outwardly from 1and='entirely aroundthe inlet opening in order-to define the' opening The end of duct 14: projects into the-interior of the roof jack through inlet opening 15, as may be seen in-Figs.:2 andS.

:The main body 16 of the roof jack is formed "by wallmeans' :extending upwardly from flange 10 around the edges of inletopeninglS. The wall means'omprises two' sidewalls "18, a front wall'20, anda'rearwall 2'2. Thetwowside Walls areflatmembers that are-preferably parallel itoeach other and perpendicular to the base flange. Frontwall20 is also flat over m'o'st-ofits extent and slopes .rearwardly'and upwardly. The front wall makes an angle'of about 35 with the plane of flange 10 is apre'ferredform of my invention, but this angle may be variedby atleast l0 either'way and still obtain the advantages of myinvention. At the upper endof the'front wall is an upstanding'flange 20a extending entirely across .the "front Wall between the two side walls.

Rear wall 22rises perpendicularly from flange 10 for a short distance and then curves smoothly forward so that portion 221: of it overhangs the front wall "like a hood. The side'walls rise above front wall 2t) and join the overhanging portion of the rear Wall; and'there is formed bythe four walls an air outlet opening of rectangular shape at '24 above the sloping front wall. Exhausted air leaves the roof jack through this opening.

Thatside .of theroof jack towards which theexhaustor outlet opening 24'is directed has been arbitrarilyde'signated as the front ,side of theiroof jack; andaccor'dingly theoppositesideis termed thefrearside.

The space inside housing 16 tapers upwardly to a comparatively restricted opening at throat 25 at the upper end of the front wall. Throat 25 is rectangular in outline and may be considered to be bounded at each side by one of the four walls of housing 16. At this throat is located shutter 26 which shuts by gravity to close the throat to backdrafts. Closing the throat keeps rain, cold air or wind, from flowing down exhaust duct 14. At the same time, the shutter is made so light in weight that the normal pressure of the exhaust air stream against the inner or under side of the shutter opens it easily, as indicated in the dot-dash position of Figs. 2 and 5.

As a means for supporting the shutter in place, it is preferred to provide at throat 25 an open rectangular frame 27 which fits snugly within the throat and engages all the housing walls. It is preferred to surround the frame with a strip 23 of felt or the like to make the frame fit tightly enough to prevent air from passing between the frame and the housing. Frame 27 consists of narrow angular members which extend around the four sides of a central opening. The frame members can be seen in Figs. 2 and 4, and may be padded on the outside with a layer of felt 29 that engages the margins of shutter 26 to effect an air-tight seal with the shutter.

Shutter 26 is pivoted at 28 on frame 27 to swing about a horizontal axis. This axis is located closely adjacent to rear wall 22 and is always above and rearward of the bottom edge of the shutter and also of the lower side of the frame, for all ordinary inclinations of base flange 10. As a consequence, the shutter is always urged by gravity toward the closed position. This is true when a roof jack is mounted on a flat roof as in Fig. 2, or on a pitched roof as in Fig. 5 because the shutter is normally disposed at about the same slope as the front walls. Roofs seldom exceed a slope of 30; and the proportions shown permit the shutter to close normally for any pitch up to and beyond 30. Shutter 26 closes in a normal manner even when the roof is pitched as deeply as 45 because, assuming the shutter to be at 35 to the flange, as is the front wall, the shutter then makes an angle of 80 with the horizontal. The further the shutter is opened, the greater the force tending to close it.

Frame 27 may be held in place in any suitable manner. Here the frame has on its rearward side a flange 27:: which is held between the rear wall and a resilient clip 30 fastened to the inside face of wall 22. Clip 30 is an elongated strip of metal which is attached to the rear wall of the housing along its lower edge, as by spot welding, to form an air-tight joint. The strip extends across substantially the full width of wall 22, as may be seen in Fig. 4. Flange 27a on the frame is inclined at the proper angle to lie against this spring clip when it is inserted between the elip and the housing wall, as shown in Fig. 2. Light pressure of the two members against each other forms an air-tight joint at this point. The resilient nature of strip 30 allows it to maintain this sealing contact with the frame while at the same time moving toward or away from the rear wall to accommodate minor variations in the front-to-rear dimension of frame 27.

Extending entirely across the side of this frame is another depending flange 27b which is parallel to and in engagement with flange 20a of the front wall. Contact between these two flanges maintains an air-tight connection at this point; and the two flanges may be held together by any suitable means, as for example by metal screw 31.

Also mounted on the lower edge of frame 27 is baffle 32 which extends entirely across the frame. This angular baflle member shields the edge of the shutter from air currents which enter the roof jack through outlet opening 24 and might otherwise blow under the edge of shutter 26 and between shutter and frame 27 Such entering air currents are directed upwardly away from the edge of the shutter by the battle. In general, gusts of wind and the like blowing into opening 24 strike against the underside of curved wall 22a of the housing and are then directed 4 downwardly against the outside face of shutte direction to more firmly close the shutter.

It is preferable to close opening 24 against the entry of birds by providing screen 34 at the opening, which screen may be of relatively large mesh. Cut to the same size as the outlet opening in the housing, the screen may be pushed into place, and is then held frictionally. A narrow metal clip 35 attached to the housing at one end may be then bent into a U-shape to engage the under side of the screen and hold it against dropping downwardly.

Rectangular inlet 15 is considerably larger than throat 25. Although both openings have one dimension in common, since they both extend the full distance between side walls 18, in the other dimension inlet 15 is two or more times the size of the throat. This is done in order to accommodate the roof jack to exhaust ducts of various sizes and shapes, irrespective of whether or not the base of the jack is sloped with respect to the duct because it is mounted on a pitched roof. A large variety of sizes and shapes of exhaust ducts are commonly encountered. An oblong duct approximately ten inches by three inches is used frequently in interior partition walls. A six inch square duct is also frequently encountered while in round ducts diameters are as large as six to eight inches. Since the largest of these dimensions is ten inches, the inlet opening 15 is preferably made slightly larger than ten inches in each dimension. This has the further advantage that a square or round duct up to eight inches can also be easily accommodated, even on a steeply pitched roof. This situation is shown in Fig. 5 where duct 14a represents a typical round duct.

On a-fiat roof, the opening required to receive the end of the exhaust duct has the same dimensions as the exhaust duct itself. However, on a sloping roof, the inclination of the plane of the inlet opening requires that it have a dimension from front to rear considerably greater than the corresponding dimension of the exhaust duct. At the same time, the net area at the throat need only be of approximately the same magnitude as the cross sectional area of the duct so that the throat can be considerably smaller than the area of the inlet opening. This being the case, the forward wall of the roof jack is sloped upwardly and rearwardly to give an upwardly tapered shape to the space within the housing. It will be noted that at its point of closest approach to the rear wall, there is still suificient space between the rear wall and the front wall to allow the duct to project into the interior of the housing for at least a short distance.

The air exhausted from the end of the duct encounters the curved underside of wall 22a and is directed over a smoothly curved path to the outlet from the roof jack which faces downwardly in order to protect it from wind and rain. Actually, the direction of the exhaust stream may be changed as much as from the direction it is flowing at the time itleaves the exhaust duct. At the same time, this change in direction is made withoutcreating any pockets within the housing in which the air collects or which would offer resistance to streamline flow.

The roof jack is normally mounted with the exhaust duct as close to the rear wall as is practical in order that the air is directed as much as possible directly toward and against the under side of shutter 26. In this position the full energy of the outwardly moving air stream is available to open the shutter.

From the above description, it will be seen that various changes in the proportion or shaping of parts may be made without departing from the spirit and scope of my invention; and accordingly it is to be understood that the above description is considered as being illustrative of, rather than limitative upon, the appended claims.

I claim:

1. A closure means for an exhaust duct or the like venting through a roof, comprising; a planar flange for attachment to the roof with an air-tight seal and extending around a rectangular air inlet opening to the closure r26ina means adapted to receive an end of the exhaust duct; Wall means rising upwardly from said flange around the inlet opening therein, said wail means including a pair of parallel side walls, a rearwardly and upwardly sloping front wall, and a rear wall extending upwardly and forwardly,

said wall means defining at the upper end of the front wall a rectangular throat that is above and has not more than one-half the front-to-rear dimension of the inlet opening; a resilient clip fastened at its lower edge to the inside face of the rear wall; an open frame at the throat and having at its upper edge a flange received between the back wall and said resilient clip; cooperating means on the frame and on the upper end of the front wall engaging each other to position the frame; and a shutter pivotally mounted at its top edge to the upper side of the frame and gravity biased to normally close the opening in the frame to prevent back-draft into the duct.

2. A closure means for an exhaust duct or the like projecting through a roof, comprising: a planar flange for attachment to the roof and extending around and defining a rectangular inlet opening comprising substantially the entire underside of the closure means and adapted to receive the upper end of the exhaust duct; wall means connected to and rising from the flange at the sides of the inlet opening, said wall means including a pair of parallel side walls, a rear wall having an upwardly and a forwardly extending portion, and an upwardly and rearwardly sloping front wall that is disposed at an acute angle relative to the planar flange and terminates beneath the forwardly extending portion of the rear wall at a position spaced rearwardly from the front end of the rear wall to form with said rear wall a rectangular throat which is coextensive with the inlet opening between the parallel side walls, but has about one-half the front-to-rear dimension of the inlet opening, and said front wall and the front end of the rear wall defining with the side walls an outlet opening disposed above the sloping front wall; and shutter means at the throat.

3. A closure means as in claim 2 in which the front wall slopes at an angle of about 35 with respect to the plane of said planar flange.

4. A closure means for an exhaust duct or the like venting through a roof, comprising; a planar flange for attachment to the roof with an airtight seal and extending around a rectangular air inlet opening to the closure means adapted to receive an end of the exhaust duct; wall means rising upwardly from said flange around the inlet opening therein, said wall means including a pair of parallel, upwardly extending side walls, a sloping front wall that extends upwardly and rearwardly making an acute angle with the planar flange, and a rear wall having an upwardly extending lower portion and a forwardly extending upper portion that extends over and is spaced above the sloping front wall, said wall means defining at the upper end of the front wall a rectangular throat that is above and has substantially one half the front to rear dimension of the inlet opening, said forwardly extending portion of the rear wall joining the side walls at their upper ends to form a hood over the throat and, in cooperation with the sloping front wall, a downwardly facing outlet opening above the front wall.

References Cited in the file of this patent UNITED STATES PATENTS 203,447 Handover May 7, 1878 992,849 Chalke May 23, 1911 1,592,841 Ansell July 20, 1926 2,184,110 Anderson Dec. 19, 1939 2,300,842 Leslie Nov. 3, 1942 2,565,131 Johnson Aug. 21, 1951

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