US3691930A

US3691930A - Wind control flue and air intake assembly

Info

Publication number: US3691930A
Application number: US199415A
Authority: US
Inventors: Gerald W Stelnman
Original assignee: Intertherm Inc
Current assignee: Nortek Global HVAC LLC
Priority date: 1971-11-17
Filing date: 1971-11-17
Publication date: 1972-09-19
Anticipated expiration: 1989-09-19
Also published as: CA924566A

Abstract

A wind control flue and air intake assembly of the concentric type, particularly useful for gas furnace installations subjected to high winds. Both the air intake and the flue have caps of the same diameter and control flanges spaced inward from the lower edges of the caps. Spacedly beneath each is a horizontal plate, which directs the wind flow horizontally beneath the annular openings so provided.

Description

United States Patent 1 Steinrnan [451. Sept. 19, 1972 [s41 WINDCONTROL FLUE AND AIR 3,315,586 4/1967 Marrapese et al. ..98/62 INTAKE ASSEMBLY v 3,361,051 1/1968 Fair et al ..l26/307 A X 3,430,549 3/1969 Hershey et al ..98/62 [72] w 3,521,582 7/1970 Liden ..'....l26/85 B x [73] Assignee: Intertherm, Inc., St. Louis, Mo. V v 22 ir No 17 1971 Primary ExaminerCharles J. Myhre 1 Attorney-Jerome A. Gross [2l] Appl. No: 199,415 Related US. Application Data [571 ABSTRACT [63] continuationdmpart of 9 Oct A wind control flue and air intake assembly of the 28, 1970, abandone concentric type, particularly useful for gas furnace inv stallations subjected to high winds. Both the air intake [52] us. Cl. ..98/62, 126/307 R and the flue have p of the same diameter and [51] Int. Cl ..F23l-17/04 trol flanges spaced i ard from the lower edges of the [58] Field of Search..l26/85 B, 307 R, 307 A; 98/62, Caps. Spacedly beneath each is a horizontal plate, 98/32, 46,58 which directs the wind flow horizontally beneath the annular openings so provided. [56] References cued 7 Claims, 5' Drawing Figures UNITED STATES PATENTS 1 e r r 3,082,758 3/1963 Heiman...., ..l26/85 B X PATENTED E 3,691, 930

sum

2 or 2 FIG.4

lNVENTOR GERALD W. STEINMAN BY ATTORNEY This application is a continuation-in-part of Application Ser. No. 84,749 entitled Balanced Draft Flue and Air Intake Assembly filed Oct. '28, 1970, now abandoned. To the extent of its disclosure, said filing date is claimed for priority.

BACKGROUND OF THE INVENTION This invention relates to concentric flue and air intake assemblies, such as are conventionally used on furnaces of mobile homes and the like. In such concentric construction, the inlet air is drawn beneath an annular cap located below the upper end of the flue, into a concentrically outer pipe which serves as an air intake. The furnace draws this air for combustion; the products of combustion rise upwardly in the flue and pass outward beneath a flue cap above the level of the air intake cap.

In normal operation, negative pressures may be measured in both the air intake pipe and in the flue pipe as long as the furnace is burning. The pressure upstream of the flame will be higher (that is, less negative) than that downstream of the flame; their difference measures the draft.

The concentric arrangement of air intake andflue is conventionally referred to as providing a balanced draft, that is, one which is less affected by changes in wind direction and velocity than if the air intake were remote from the flue cap. However, such concentric construction has heretofore failed to provide a reliably constant draft. A truly balanced draft would be one whose measured pressure difference was unaffected by wind velocity; and the term balanced is used herein only in a slightly broader sense, that is, where the effect of wind velocity is minimized. While it is desirable that wind velocity shall be balanced to have relatively little effect, it is also desirable that whatever effect it has shall increase the draft rather than reverse it. A flue so designed may be called a positive draft flue. Bot balanced and positive draft flues may appropriately be denominated wind-control flues. Where the natural flue draft is not supplemented by a blower, as in most Hershey and Johnson, the flue and air intake caps are supported from below by external projecting vanes. These vanes interrupt the flow of air, to a varying extent, as the wind direction changes, causing varying conditions of stagnation and turbulence. Even as to the vertical cylindrical surfaces, aerodynamic effects resulting from change in wind velocity are usually ignored. No provision is ordinarily made to avoid the unbalance resulting from stagnation pressure which may build up on the windward side, or turbulence which may build up on the leeward side, of the air-in take and flue pipes.

SUMMARY IN THE INVENTION -In the present invention, structure is provided which minimizes these undesirable effects, to provide a draft which is safely controlled throughout the range of normally anticipated wind velocities and regardless of changes of wind direction. Although useful for many types'of combustion devices, it is particularly useful for gas furnace installations in localities where high winds may be encountered. It uses an air intake pipe concentric with the. flue but of lesser height; and having an annular cap preferably of the same diameter as the flue cap above it. Annular spaces inward of .the edges of these caps, are substantially identical; the inner edge of each annular space is provided by'a flange extending outward from one of the vertical cylindrical surfaces of the assembly. Spaced beneath each flange is a horizontal plate, extending outward from the pipe to the outer edge of the cap, its upper surface being unimpeded by any external supports. Winds flow through the annular regions so provided. Although wind velocity will cause areas of stagnation pressure and of turbulence immediately adjacent to the pipe surfaces, the flanges minimize communication of such stagnation pressure or turbulence from these regions into the intake and flue.

In the first embodiment herein described, the flanges which extend toward the caps to define the inlet and outlet areas, are mounted on pipes of equal diameter; here the wind effects are balanced. In the alternate embodiment, the flange within the flue cap is extended inward farther than the flange below it. The result is to assure positively a pressure differential at the flue outlet even though such differential may increase with wind velocity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is, a side view of a balanced draft flue and air intake assembly embodying the present invention, shown partly in elevation and partly in section.

FIG. 2 is a sectional view taken along line 22 of FIG. 1.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1.

FIG. 4 is a side view, partly in section, of an alternate embodiment of a wind control flue and intake assembly, modified to provide positive draft.

FIG. 5 is a sectional view taken along line 55 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The combined flue and air intake assembly illustrated in FIGS. 2 and 3 of the drawings is a balanced draft flue suited for use for mounting through the roof of a mobile home, not shown. Since the parts described are formed of sheet metal, and the joints and seams mentioned are spot welded, the division of the total structure into parts may be varied, depending on considerations of convenience, to achieve the configuration and functions described.

Atop the mobile home roof, a conventional flanged roof jack generally designated 10 is employed. Adjacent to its horizontal mounting flange 11 is a larger vertical cylindrical portion 12 and a smaller diameter upward continuing portion 13, each having a circumferential outward

bead

14, 15. As seen from FIG. 1, the.

as an upper continuing part of an air intake pipe, made up of several parts as herein described and generally designated 20. One of these parts, nested within the larger portion 12 and caught within its bead 14, is lower lowered air intake pipe 21, which communicates downwardly to the top annular air intake of a conventional gas furnace not shown.

Extending upward from the central flue connection of such furnace is a vertical flue pipe 23, concentric with and smaller than the upper roof of jack portion 13. The flue pipe 23 terminatesupwardly in an upper end 24 at a level spacedly above that of the flue pipe 23.

The remainder of the structure to be described is supported from the upper end 24 of the flue pipe 23 and rests upon and is. stabilized by the upward roof jack portion 13 and its bead 15. At the outer side of the flue upper end 24 is an annular closure plate 25, flanged downwardly at both its inner an outer edges, which extends radially outwardly to a diameter equal to that of the upward continuation 13. Its function is to prevent flow communication between the air intake pipe and the upper cap described hereafter. Its inner flange is secured to the flue end 24 by spot welding. Spot welded to its upper surface is a horizontal annular plate 26 whose inner diameter is larger than that of the flue 23 and which extends to a substantially greater outer diameter, terminating in an outer margin 27. On the outer margin 27 four vertical cylindrical spacers 28 are mounted by screws29 to support the outer lower edge flange 31 of a flue cap generally designated 32. The flue cap flange 31 is the same diameter as the plate 26;

immediately inwardly of it, ata slightly less diameter,

the'cap 32 has a substantially cylindrical outer wall 33 which rises to an imperforate top wall 34 spaced above the end 24 of the flue pipe 23.

Descending from the lower surface of the closure plate and spotwelded to its outer flange is a principal spacer pipe portion 36. Secured to the plates upper surface is a supplementary upper spacer pipe portion generally designated 37. In the spot welded embodiment shown, the supplementary upper spacer pipe portion 37 is the cylindrical portion of a Z-shaped ring 38 whose lower flange is joined by spot welding to the plate 26. Considering it as an upper spacer pipe, the height of the ring 38 is equal to the height of the cylindrical spacers 28. An upper, radially outward extending flange 39 of the Z-shaped ring 38 extends horizontally from the pipe portion 37 radially outward toward the lower edge flange 31 and ends spacedly therefrom in a flow control edge 40.

From the lower surface of the closure plate 25, the spacer pipe portion 36 extends downwardly to be joined about a top central flange of an annular top wall. 42 of an annular air intake pipe cap generally designated 43. The cap 43 extends outward from the spacer pipe portion 36 to the same radial extent as the flue cap wall 33, merging into a downward extending wall 44 of the same diameter as the wall 33 and having a similar lower edge flange 45.

Four external brackets 47, stamped of sheet metal, extend upwardly from the outer part of the annular top wall 42, onto which they are based, to support the outer edgeof the annular plate 25 at and below each of the spacers 2 8, as shown.

Four cylindrical spacers 48, formed like the spacers 28 and held by screws 29, extend downwardly from the lower edge flange 45 of the air intake cap 42. Their lower ends are based on the outer edge of a horizontal annular plate 50, attached by an inner flange to a short air intake pipe portion 51, which fits te'lescopingly over and about the upward continuation 13 of the roof jack 10. Its lower edge rests on the bead 15; and it is secured by four machine screws 52.

At the upper edge of the connector portion 51 spacedly above the plate 20 at the level. of the cap flange 43, and formed outward from a ring angle generally designated 53, a horizontal flange 54 similar to the flange 39 extends radially outward. lt terminates in a flow control edge 56, like the flow control edge 40 in the flue cap 32, which provides an annular space for air flow inwardly of the intake cap wall44. Thus, the functioning air intake includes the angle 53, pipe connectorfportion 51, upward roof jack 13 and air intake pipe portion 21.

Defined upwardly by the air intake cap flange 45 and the ring flange 54, inwardly by the connector pipe 51, and downwardly by the upper surface of the plate 20, is an annular region of exposure to the intake pipe 21. A correspondingregion of exposure of air to the flue pipe 23 is defined by the flue cap flange 31, Z-shaped ring 38, and upper surface of the plate 25. These annular regions of exposure have corresponding outer diameters and inner diameters; their vertical extent may be the same or may be varied at the election of the designer. For example, the vertical extent of the region of exposure at the flue cap may be varied by changing the length of the vertical spacers 28. 4

As wind enters into these areas of exposure, it will blow across the top surfaces of the plates 26, 50'unimpeded by any supporting vanes as were typically used in the prior art; because outward of the cylindrical or pipe surfaces there present (that is, the ring38 and the air intake connector portion 51) no structure impedes the air flow other than the

small spacers

28,48

Also, wind, confined to flowing substantially horizontally into the regions of exposure, will tend to flow out from these regions without affecting the draft. This has been substantiated by exhaustive tests. The following explanation is offered for this result.

Natural draft, caused by combustion, sets up an inflow upwardly into the air intake cap 43 and downwardly into the air intake pipe 51 as shown by arrows in FIG. 1, with the flow gases departing as shown by the arrows upwardly in the flue pipe 23 and outwardly through the flue cap 32. Outflow arrows are shown in FIG. 2 and inflow arrows in. FIG. 3. These figures are taken looking upward at the flanges 39, 54 and their flow control edges 40,56. These figures also show, by dashed arrows, the effect of a wind flowing from the left. Such a wind will set up an area of stagnation 58 shown in phantom lines on the windward sides of the ring 37 and intake connector 51, and a somewhat similar area of turbulence 59 on their leeward sides. The radial extent of the flanges 39, 54 is set at such chosen width that at a fairly high wind velocity which may be encountered, say 40 miles per hour, the areas of stagnation 58 will not exceed the flange width and areas of turbulence 59 on the leeward side may be only slightly in excess of the flange width. With the flue and air intake shielded by these flow control flanges 39, 54, the superposition of winds of substantial velocity on the normal draft pattern will not materially affect the combustion system. At these wind velocities, there will be no direct wind inflow into either the flue cap 32 nor the air intake cap 43, and neither the stagnation pressure nor the turbulence will spill to any substantial extent over the flow control edges 43, 56.

1f extremely high wind velocities are anticipated, the altemate embodiment of the present invention, illustrated in FIGS. 4 and 5, may be utilized to aflord the security of positive draft, with only a small lessening of balance. The principal differences in structure are those attendant to providing the flue cap with a broader wind control flange than that within the air intake cap, so that turbulence and stagnation pressures can never be communicated to the flue pipe.

In FIG. 4 most of the parts of the modified air intake cap 143 are identical with the corresponding parts of the embodiment of FIG. 1', these are identically numbered and will not again be described. The differences in construction are principally the following. The air intake pipe cap 143, whose outer portions are like those of the corresponding cap 43 of FIG. 1, extends radially inward to a flanged juncture with the outer surface of the flue pipe 123 slightly below its upper end. The height of the flue pipe 123 is such as to bring its upper end to the level of the flange 31 of the flue cap 32. The external brackets 47 which extend upward from the cap 143 a distance spacedly below the flange 31, mount a horizontal annular flow directing plate 126 which extends radially to and has a flanged juncture with the flue pipe 123. The spacing of the plate 126 below the flange 31 is preferably equal to the spacing of the lower plate 50 beneath the air intake pipe cap 143.

An annular flanged plate 139 at the level of the flue cap flange 31 has an inner downward flange 138 which is joined to the outer surface of the top end of the flue pipe 123. The annular width of the plate 139 is such that its outer flow-control edge 140 is spaced inwardly from the lower end of the cylindrical wall 33 of the cap 32 by a spacing equal to that of the flange 54 within the air intake cap 143. Thus the inlet of the air intake and V the outlet of the flue are provided with equal openings,

spaced vertically from each other.

in contrast to the embodiment of FIG. 1, the spacer pipe 36 and upper spacer pipe portion 37 are dispensed with, so that the greater width of the annular plate 139 will insure against any spread, into the flue 123, of stagnation and turbulence pressure. Comparing with the areas of stagnation and turbulence designated 58 and 59 respectively, in FIGS. 2 and 3, larger areas of stagnation and turbulence at extremely high wind velocities are shown in FIG. 5, designated 158 and 159. The width of the flanged plate 139 is so great that even such large areas of stagnation and

turbulence

158, 159 will not overflow the control edge 140. Simultaneous large stagnation and turbulence areas at the air intake pipe cap 143 are not dangerous even though they overflow the intake control edge 56, because they add positive pressure at the intake. Hence, by these modifications, a small loss in balance' of the draft is compensated for by the assurance that high winds will never result in reversal of the draft.

Should a closer approach to balance be desired, with some lesser provision for assuring positive draft at less extreme wind velocities, an upper spacer pipe portion might, be added whose diameter was intermediate between that of the flue pipe 123 and the air intake pipe 20. Thus, the change from balance to the assurance of positive draft at higher velocities is here achieved by maintaining the annular flue outlet area similar to the air intake area but broadening the flue cap control flange inwardly.

I claim:

1. A balanced draft flue and air intake assembly, comprising a vertical flue pipe,

an air intake pipe concentric with and of larger diameter than the flue pipe and having an upper end terminating spacedly below the upper end of the flue pipe, I

a spacer pipe of the same said larger diameter, positioned spacedly above the air intake pipe, the upper end of said spacer pipe being at a level near that of the upper end of the flue pipe,

a flue cap having a central portion spacedly above the top of the flue pipe and extending to a diameter substantially greater than the air intake pipe, the cap including a downward extending outer wall terminating in a lower edge,

an annular air intake pipe cap extending radially outward from the lower end of the spacer pipe and having an outer wall terminating in a lower edge,

annular closure means between the flue pipe and the spacer pipe to prevent flow communication between the flue cap and the air intake pipe, together with a horizontal annular plate positioned spacedly below the lower edge of the flue cap and extending from an outer diameter in registration therewith, inwardly to the spacer pipe, and

a similar horizontal annular plate positioned spacedly below the lower edge of the air intake cap and extending from an outer diameter in registration therewith inwardly to the air intake pipe,

whereby to provide, in the spacings between said plates and the lower edges of the caps above each of them, annular regions of exposure of the air inlet pipe and the flue pipe.

2. A balanced draft flue and air intake assembly as defined in claim 1, together with a horizontal flange positioned within the flue pipe cap and extending from the spacer pipe radially outward toward the lower edge of said cap and ending spacedly therefrom in a flow control edge, and

a similar horizontal flange positioned within the air intake pipe cap and extending from the intake pipe radially outward toward the lower edge of said intake pipe cap and ending spacedly therefrom in a flow control edge,

whereby to establish openings, inwardly of said caps, upwardly into the air intake pipe and downwardly out of the flue pipe, said openings being spacedly outward of pipe surfaces of the same diameter, thereby to minimize wind upflow and stagnation and turbulence effects.

3. A wind-control flue and air intake assembly, comprising a vertical flue pipe,

an air intake pipe concentric with and of larger diameter than the flue pipe and having upper end air entrance means spaced below the upper end of the flue pipe, r Y

a flue cap having a central portion spacedly above the upper end of the fluepipe and extending to a diameter substantially greater than the air intake pipe, the cap including a downward extending outer wall terminating in a loweredge,

means to prevent flow communication between the flue cap and the air intake pipe,

an annular air intake pipe cap having an outer wall radially inward of saidair entrance means and of the same diametric extent as that of the flue pipe cap, said wall terminating in a lower edge, together with an annular member positioned spacedly below the lower edge of the flue cap and having an upper plate surface extending from an outer diameter, in registration with the lower edge of the flue cap, inwardly to a pipe surface above said air entrance means, and

an annular member positioned spacedly below the lower edge of the air intake cap and having an upper plate surface extending from an outer diameter, in registration with the lower edge of the air intake cap, inwardly to the air intake pipe,

whereby to provide, in the spacings between said plate surfaces and the lower edges of the caps above each of them, annular regions of exposure of the air inlet pipe and the flue pipe.

4. A wind-control flue and air intake assembly as defined in claim 3,

said upper plate surfaces being substantially unimpeded, whereby changes in wind direction cause no substantial change in draft. 5. A wind-control flue and air intake assembly as defined in claim 3, together with v a horizontal flange positioned within the flue pipe cap and extending from the said pipe surface above said air entrance means, radially outward toward the lower edge of said cap and ending spacedly therefrom in a flow control edge, and

a similar horizontal flange positioned within the air intake pipe cap and extending from the intake pipe radially outward toward the'lower edge of said intake pipe cap and ending spacedly therefrom in a flow control edge,

whereby to establish, spacedly above said upper plate surfaces, openings upwardly into the air intake pipe and downwardly out of the flue pipe.

6. A balanced draft flue and air intake assembly,

comprising a wind-control flue assembly as defined in claim 5,

wherein the said pipe surface above said air entrance means, from which the horizontal flange within the flue pipe cap extends, is of the same diameter as the air intake pipe, and

the outer diameter of said flange is substantially equal to that of the horizontal flange within the intake pipe cap.

7. A positive draft control flue and air intake assembly, comprising a wind-control flue assembly as defined in claim 5,

wherein the said pipe surface above said air entrance means,

from which extends the horizontal flange within the flue pipe cap, is of substantially smaller diameter than the air intake pipe, and

the outer diameter of said flange is substantially equal to that of the horizontal flange within the air intake pipe cap,

whereby to provide greater protection against stagnation pressure and turbulence communication within the flue pipe cap than within the air intake pipe cap, thereby to positively assure against draft reversal from high winds.

Claims

1. A balanced draft flue and air intake assembly, comprising a vertical flue pipe, an air intake pipe concentric with and of larger diameter than the flue pipe, and having an upper end terminating spacedly below the upper end of the flue pipe, a spacer pipe of the same said larger diameter, positioned spacedly above the air intake pipe, the upper end of said spacer pipe being at a level near that of the upper end of the flue pipe, a flue cap having a central portion spacedly above the top of the flue pipe and extending to a diameter substantially greater than the air intake pipe, the cap including a downward extending outer wall terminating in a lower edge, an annular air intake pipe cap extending radially outward from the lower end of the spacer pipe and having an outer wall terminating in a lower edge, annular closure means between the flue pipe and the spacer pipe to prevent flow communication between the flue cap and the air intake pipe, together with a horizontal annular plate positioned spacedly below the lower edge of the flue cap and extending from an outer diameter in registration therewith, inwardly to the spacer pipe, and a similar horizontal annular plate positioned spacedly below the lower edge of the air intake cap and extending from an outer diameter in registration therewith inwardly to the air intake pipe, whereby to provide, in the spacings between said plates and the lower edges of the caps above each of them, annular regions of exposure of the air inlet pipe and the flue pipe.

2. A balanced draft flue and air intake assembly as defined in claim 1, together with a horizontal flange positioned within the flue pipe cap and extending from the spacer pipe radially outward toward the lower edge of said cap and ending spacedly therefrom in a flow control edge, and a similar horizontal flange positioned within the air intake pipe cap and extending from the intake pipe radially outwaRd toward the lower edge of said intake pipe cap and ending spacedly therefrom in a flow control edge, whereby to establish openings, inwardly of said caps, upwardly into the air intake pipe and downwardly out of the flue pipe, said openings being spacedly outward of pipe surfaces of the same diameter, thereby to minimize wind upflow and stagnation and turbulence effects.

3. A wind-control flue and air intake assembly, comprising a vertical flue pipe, an air intake pipe concentric with and of larger diameter than the flue pipe and having upper end air entrance means spaced below the upper end of the flue pipe, a flue cap having a central portion spacedly above the upper end of the flue pipe and extending to a diameter substantially greater than the air intake pipe, the cap including a downward extending outer wall terminating in a lower edge, means to prevent flow communication between the flue cap and the air intake pipe, an annular air intake pipe cap having an outer wall radially inward of said air entrance means and of the same diametric extent as that of the flue pipe cap, said wall terminating in a lower edge, together with an annular member positioned spacedly below the lower edge of the flue cap and having an upper plate surface extending from an outer diameter, in registration with the lower edge of the flue cap, inwardly to a pipe surface above said air entrance means, and an annular member positioned spacedly below the lower edge of the air intake cap and having an upper plate surface extending from an outer diameter, in registration with the lower edge of the air intake cap, inwardly to the air intake pipe, whereby to provide, in the spacings between said plate surfaces and the lower edges of the caps above each of them, annular regions of exposure of the air inlet pipe and the flue pipe.

4. A wind-control flue and air intake assembly as defined in claim 3, said upper plate surfaces being substantially unimpeded, whereby changes in wind direction cause no substantial change in draft.

5. A wind-control flue and air intake assembly as defined in claim 3, together with a horizontal flange positioned within the flue pipe cap and extending from the said pipe surface above said air entrance means, radially outward toward the lower edge of said cap and ending spacedly therefrom in a flow control edge, and a similar horizontal flange positioned within the air intake pipe cap and extending from the intake pipe radially outward toward the lower edge of said intake pipe cap and ending spacedly therefrom in a flow control edge, whereby to establish, spacedly above said upper plate surfaces, openings upwardly into the air intake pipe and downwardly out of the flue pipe.

6. A balanced draft flue and air intake assembly, comprising a wind-control flue assembly as defined in claim 5, wherein the said pipe surface above said air entrance means, from which the horizontal flange within the flue pipe cap extends, is of the same diameter as the air intake pipe, and the outer diameter of said flange is substantially equal to that of the horizontal flange within the intake pipe cap.

7. A positive draft control flue and air intake assembly, comprising a wind-control flue assembly as defined in claim 5, wherein the said pipe surface above said air entrance means, from which extends the horizontal flange within the flue pipe cap, is of substantially smaller diameter than the air intake pipe, and the outer diameter of said flange is substantially equal to that of the horizontal flange within the air intake pipe cap, whereby to provide greater protection against stagnation pressure and turbulence communication within the flue pipe cap than within the air intake pipe cap, thereby to positively assure against draft reversal from high winds.