US2127177A - Warm air furnace structure - Google Patents

Description

Aug. 16, 1938. o. J. KUENHOLD 2,127,177

WARM AIR FURNACE STRUCTURE Original Filed Oct. 7, 1933 4 Sheets-Sheet l Zhmentor OTTO J. KUENHOLD Gttornegs A 1938- o. .J. KUENHOLD 2,127,177

WARM AIR FURNACE STRUCTURE Original Filed 001:. '7, 1933 4 Sheets-Sheet 2 ZSnventor OTTO J. KUENHOLD Gttornegs Aug. 16, 1938. o. J. KUENHOLD WARM AIR FURNACE STRUCTURE Original Filed Oct. 7, 1933 4 Sheets-Sheet 3 with], m

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Aug. 16, 1938; o. J. KuENHoLb 2,127,177

WARM AIR FURNACE STRUCTURE Original Filed Oct. 7, 1933 4 Sheets-Sheet 4 Zhwentor OTTO J. KUENHOLD www attorneys Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE.

WARM AIR FURNACE STRUCTURE Original application October 7, 1933, Serial No.

Divided and this application June 8,

1937, Serial No. 147,068

10 Claims.

This invention relates to improvements in furnaces for warm air circulating systems, and has for its general objects the provision of an improved warm air furnace which has exceptionally high thermal efficiency, free air flow therethrough, equal distribution of heat into all warm air outlet ducts connected therewith, a neat and compact appearance and maximum safety of operation in use.

A further object of the present invention is the provision of an improved warm air furnace having smoothness and dependability of operation, simplicity and economy of production, ease of shipment and erection, and which is capable of manufacture in a large range of sizes from a minimum number of foundry patterns.

With the foregoing and other objects in View which will appear as the description of the invention proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the invention as herein disclosed can be made within the scope of what is claimed without departing from the spirit of the invention.

This application is a division of my copending application Serial No. 692,690, filed October 7, 1933.

The present invention will be readily understood from the following description thereof, reference being had to the accompanying drawings in which Fig. 1 is a vertical, longitudinal sectional view of a furnace constructed in accordance with one embodiment of the invention, the view being in the plane of line Il, Fig. 3; Fig. 2 is a detail cross-sectional view of a portion of one of theside or auxiliary heat convectors of the furnace, the view being in the plane of the line 2-2, Fig. 5; Fig. 3 is a horizontal sectional view of a furnace constructed in accordance with another embodiment of the present invention, there being in this view an unbalanced arrangement of side or auxiliary heat convectors, three on one side and two on the other side of the central or main heat convector, whereas in Fig. 1 there is a balanced arrangement of side or auxiliary heat convectors, there being two on each side of the central or main heat convector; Fig. 4 is a detail vertical sectional View of the vent manifold for the side or auxiliary heat convectors, the view being in the plane of line 4-4, Fig. 5; Fig. 5 is a vertical, transverse sectional view of the furnace, the View being in the plane of line 55, Fig. 1; and Figs. 6 to 10 inclusive are enlarged sectional views of the draft hood and the explosion relief means associated therewith; Figs. 6 and '7 being vertical sectional views on the line 6-7t--1, Fig. 9; Fig. 8 being a vertical sectional view on the line 8-8, Fig. 9; Fig. 9 being a vertical sectional view on the line 99, Fig. 8; and Fig. 10 being a vertical sectional View on the line l0li3, Fig. 9.

In its general aspects, the present furnace includes a battery of generally parallel and generally vertically disposed heat convectors 60, 10 through which flow the heated products of combustion and between and around which flow the air to be heated.

In the main and central heat convector are located the fuel burners of the furnace, there being three gas burners 5!] in the embodiment of the invention here shown. Combustion is completed in the liberal sized combustion compartment 55 of the main convector and the burned gases rise or flow upwardly directly to the top of said convector, from which they pass laterally into the top cross passages 61 and are distributed thereby into the side or auxiiary heat convectors 10. In these side or auxiliary convectors, the gases are gradually cooled by the upwardly flowing air surrounding said convectors and as the gases cool they contract, become heavier and gradually gravitate downwardly toward auxiliary convector outlets at the lower ends thereof. Said outlets communicate with a common, transversely and generally horizontally disposed ventmanifold into which-the cooled gases drop and then they pass to and through the manifolds vent outlet into and through the generally vertically disposed vent duct 92 by reason of their being warmer and lighter than the atmosphere with which the open upper end of te vent duct 92 communicates. From vent duct 92, the vent gases are discharged into an open bottom draft hood 100, the top of which is tapped by a vent'pipe [06 which conducts said gases to a chimney or the like.

The circulating air of the heating system enters the furnace through an intake opening in the rear wall of the furnace casing, said air coming from the furnace room or the cold air return duct, and being impelled either by natural gravity circulation or by an air fan or blower 122, Fig. 5. .Upon entering said intake opening the air passes upwardly between and around the heat convectors, as shown by the arrows in Fig. 1, into the plenum chamber in the, top of the furnace and from this chamber, the heated air passes to the rooms to be heated through warm air ducts in the usual manner.

The heat convectors 60, 10 may be made of pressed or cast metal, in two half sections bolted, riveted or otherwise suitably secured together at their peripheries, or they may be made in one piece cored castings, the former method being here shown.

The purpose of the forwardly extending inlet to manifold 80 is to tap the vent gases from the bottom of the side or auxiliary heat convectors so as to draw off therefrom only the heaviest and therefore the coolest gases. Inasmuch as the vent manifold is located rearwardly of the heat convectors the upward flow of the air currents between and around the convectors is not interfered with or disturbed in any way. As shown, the vertically disposed vent duct 92 from the vent manifold outlet is located close to the rear casing panel of the furnace and special provisions are made for conducting the vent gases from the side or auxiliary convectors to the vent manifold outlet in as short and direct a course as possible, the cross area of the vent manifold being of extra liberal size, as will be later referred to.

The draft hood I serves the usual functions of a draft hood, the baflle plate I02 thereof deflecting down drafts from the vent duct 92 and by having the draft hood open to atmosphere at its lower end, the upward draft or suction at the vent manifold, at the lower end of the vent duct 92, is limited to that due to the small rise of said vent duct.

The features of the present furnace giving safety against internal gas explosion will now be described. Notwithstanding the superior efficiency of gas furnaces employing diving flue circulation of combustion products, such as herein disclosed, they have been objected to because the lighter-than-air gases, from accidentally opened or extinguished main burners and pilots or from burners supposedly but not quite closed by automatic control devices, collect and remain trapped for long periods of time in the upper fines of the furnace. To overcome this objection, I have arranged a direct by-pass passage 1 ID from the top of the main or central heat convector, in which the furnace burners are located, into the furnace draft hood I00 below the down draft baffle I02 thereof, as clearly shown in Figs. 3 and 5.

Referring now to Figs. 6 to 9 inclusive, it will be noted that a suitable closure III is provided for the outlet of this relief passage H0, said closure being pivoted at its upper end on a corrosion-proof pin I03 and being preferably provided on its inner surface with suitable packing material H2. This relief closure has a lug H3 extending from one side thereof, see Fig. 9, and to this lug one end of a thermostatic metal band I I4 is riveted or otherwise suitably secured. When heated by vent gases passing through the draft hood N30, to which gases said band is exposed, the thermo-metal of the band bends it to the position shown in Fig. 6, with consequent movement by gravity of the relief closure to closing position, inasmuch as its pivot pin I03 is located inwardly, as shown, from its central gravity plane. Should the vent gases flowing through the draft hood cool, either due to turning off or accidental extinguishment of the furnace burners, the thermostatic band will bend inwardly toward the front of the furnace, as shown. in Fig. '7, and in so doing, will engage an adjustable stud or lift pin I I with consequent pushing of the relief closure partly open, as shown in Fig. 7. Any

lighter-than-air gases which may collect at the top of the main convector or at the tops of the cross-connected side convectors therefore, will be vented from such convectors and will pass into the draft hood and out through its top outlet to the chimney.

When the furnace burners are again turned on, the hot gases, as soon as they reach the upper end of the main convector, escape through the now open relief passage 1 H1 and in so doing strike the thermo-metal band H4 on their way to the chimney. The high heat of said gases promptly causes the thermo-metal band to bend outwardly,

- as in Fig. 6, permitting the relief closure to close by gravity and such closed position of said gate is maintained by the hot vent gases coming up into the draft hood from the vertical bent duct 92. The relief closure, therefore, remains in closed position, out of contact with the lift pin H5, as long as the main burners are on and hot gases are flowing through the draft hood as the result thereof.

The proportions of the parts, especially those of the thermo-metal band H4, and the adjustment provided at the lift pin H5, may be such that any desired position of the relief closure relative to the volume of gas being burned may be secured. For instance, the relief gate may be cracked or opened but slightly when only the pilot burner is on but closed as soon as any gas is burned by one of the main burners.

It is to be noted that the thermo-metal band H4 is exposed to the highly heated gases escaping through the relief passage H0 only for very brief periods, inasmuch as it will close the relief closure before it (the band) can become excessively heated. N 0 work or strain is imposed upon the thermo-metal band, therefore, except when it is cool or almost cool. When it is heated, it is out of contact with the lift pin H5 and therefore quite free to assume its normal outwardly bent position in accordance with the temperature of the vent gases to which it is exposed. The thermo-metal band, for adjustment, etc., is always accessible through the open bottom of the draft hood, and inasmuch as said band is constantly under varying temperature, it will effect frequent movements of the relief closure and thus effectively prevent sticking of said closure. It is to be noted also that the relief passage is located below the down draft diverting bafile I02 so that any chimney down draft occurring while the relief passage is open, as for instance while only a pilot flame is burning in the furnace, cannot cause extinguishment of said flame or interference with the venting of the furnace when cold.

It is to be clearly understood that the function of the above described automatic opening of the relief closure while the furnace is cold is not for the purpose of starting a circulation in the furnace or of performing any such function as a by-pass damper to aid in the operation of the furnace, Such aids are not needed in the slightest degree in the present furnace and the described operation of the relief passage would not prove effective for such purposes if they were so needed. The extent of opening of the relief passage is sufficient to drain off or vent and thereby prevent any considerable accumulation of explosive gas and air mixtures within the convectors of the furnace and to continuously drain off or vent gases which originate from leaky valves and the like. A thermostatic safety pilot is provided to prevent long continued accidental gas flow into the heat convectors in anyextensive volume. Another function of my-thermostatic relief passage is'to drain off combustion products when only a. small pilot flame is in operation, which combustion products might otherwise fill the convectors with carbon dioxide and smother the flame under certain conditions.

The relief passage and its closure have stillanother function and that is to act as an automatic safety pressure release in case of internal explosion of gases. Research work upon the present furnace structure by exploding various mixtures of gases placed into the convectors indicates that the gravity hung fire door 4! at the front of the furnace acts as an effective means to relieve the pressure of an explosive from the main convector to an extent sufficient to prevent damage thereto. The vent manifold and its outlet and probably other causes seem to prevent formation of destructive pressures at the lower ends of the side convectors. To similarly relieve pressures due to internal explosion occurring at the upper ends of the side convectors, the relief passage I Ill is provided, being connected directly to the upper end of the main convector so as to be able to successfully relieve excessive explosive pressures at the top ends of the side convectors through the top cross passages BI as well as at the top end of the main convector.

An internal explosion always originates in the vicinity of the main burner or burners, the pilot burner or burners or the fire door. Such an explosion will instantly fling the fire door open and the conflagration and pressure wave, travelling upwardly, promptly flings the relief closure IIi wide open, thereby permitting immediate escape of unburned and burning gases and relieving the compression of the exploding mixture. The sudden force and the rapidity of the explosion are thus effectively reduced, with consequent reduction of the internal pressure to such a great ex tent that the convectors can'be designed to resist such explosive force without the necessity of excessive metal thickness.

Heretofore, explosion relief doors have been so arranged that the explosion wasvented into the interior of the furnace casing. My method of venting an explosion into an open bottom draft hood arranged as herein shown and described is a material improvement over anything else of this kind heretofore attempted- Referring to Fig. 8, it will be noted that when the relief closure III flies open, it will strike the down draft baffie I02. Ordinarily, it would dis place or damage this baflle, putting it out of service, and to avoid this, said baffle M32 is hinged at its top and drops by gravity to its normal operating angle as shown in Fig. 10, at which angle it is held by some such stop means as the lug I04. After the explosion, the relief closure I will drop by gravity to its normal working position and the baffle plate I02 will similarly drop downward. The thermo-metal band I I I will not necessarily be damaged in any way inasmuch as it is fairly thick and swings upwardly out of the way along with the relief closure. The escaping and generally burning gases will strike the outer, downwardly inclined wall of the draft hood and will be deflected downwardly thereby, thus tending to prevent ignition of flammable surroundings. The flange I I6 of the relief passage conduit serves to securely hold the draft hood from being blown outwardly by an explosion, such flange being pref erably secured by bolts I I! through the inner wall of the draft hood and the back wall of the furnace casing (Fig. 10). When the relief gate is flung open by an explosion, it causes the baffle plate I02 to close the outlet 35 of the draft hood into the smoke pipe I06 connected thereto and this tends to prevent spread of the explosion into and hence damage of the vent pipe, inasmuch as the .draft hood outlet will usually be closed a fraction of a second ahead of the emission of flaming gas from the relief passage III The described combination of (first), means to prevent or at least reduce accumulation of explosive gas mixtures within the heat convectors and (second), means to reduce the severity of an explosion should it occur, by relieving the pressure at a point approximately half-way between the fire door relief means and the vent exits where'the side convectors enter manifold Mi constitute important and effective safety features.

It is desirable also to ventilate the control chamber to prevent accumulation of gases seeping out at joints, valve glands and the like, and this can be done by providing louvered or other suitable openings, as at 25, in the control chamber front panel 24. Inasmuch as this would result in the passage into the furnace room of any gas leakage in the control chamber, I provide said control chamber with an outlet 40 communicating directly with the burner compartment 55 located directly above said outlet. As the burners, during operation thereof, constantly draw air through the outlet 40 of the control chamber, continuous ventilation of said chamber is effected, the openings 25 in the control chamber front wall 24 being used for inlet purposes only. Any leaks from the gas control manifold system in the control chamber, therefore, will be vented through the furnace lines to the chimney. When the main burners are on, the control chamber will be vented to the chimney through the vent manifold 8!! and vent duct 92, and when said burners are off or their flames accidentally extinguished, said control chamber will be vented to the chimney through the safety by-pass I If] which will then be open, as was heretofore pointed out.

Further features of the present invention will be apparent to those skilled in the art to which it relates.

What I claim is: a

1. In a furnace, air heating chamber means having a portion adapted to have products of combustion flow upwardly therethrough and a portion adapted to have products of combustion flow downwardly therethrough, burner means in the first mentioned portion of said chamber means, a vent conduit for said products of combustion and communicating with the lower end of said second mentioned portion of said chamber means, a draft hood surrounding the upper end of said vent conduit and having an opening to the atmosphere, by-pass means for establishing communication between said draft hood and the upper end of the first mentioned portion of said chamber means, a down draft baflie in said draft hood for diverting down draft away from said by-pass means and said vent conduit and to the atmospheric opening of said draft hood, and thermostatically controlled closure means for said by-pass means adapted to open said by-pass means when said burner means is not in use and to close said by-pass means when said burner means is in use.

In a furnace, air heating chamber means having a portion adapted to have products of combustion flow upwardly therethrough and a portion communicating with the upper end of said first named portion and adapted to have products of combustion fiow downwardly therethrough, burner means in the first mentioned portion of said chamber means, a draft pipe for said products of combustion communicating with the lower end of said second named portion of said chamber means, vent means independent of said draft pipe and having an opening to atmosphere, by-pass means for establishing communication between said vent means and the upper end of said first named portion of said chamber means, and thermostatically controlled closure means for said by-pass means adapted to open Y said by-pass means when said burner means is not in use and to close said by-pass means-when said burner means is in use.

3. In a furnace, air heating chamber means having a portion adapted to have products of combustion fiow upwardly therethrough and a portion communicating with the upper end of said first named portion and adapted to have products of combustion flow downwardly therethrough, burner means in the first mentioned portion of said chamber means, a draft hood adjacent said furnace and having an opening to atmosphere, an explosion relief passage for establishing communication between said draft hood and the upper end of said first named portion of said chamber means, and a gravity closed gate for closing said passage.

4. In a furnace, air heating chamber means having a portion adapted to have products of combustion fiow upwardly therethrough and a portion communicating with the upper end of said first named portion and adapted to have products of combustion fiow downwardly therethrough, burner means in the first mentioned portion of said chamber means, a draft pipe for said products of combustion communicating with the lower end of said second named portion of said chamber means, a draft hood surrounding the upper end of said draft pipe and having an opening to atmosphere, an explosion relief passage for establishing communication between said draft hood and the upper end of said first named portion of said chamber means, and a gravity closed gate for closing said passage.

5. In a furnace, a chambered main heat convector generally vertically disposed and adapted to have heated products of combustion flow upwardly therethrough, a plurality of chambered auxiliary heat convectors generally vertically disposed and communicating with the upper end of said main convector and adapted to have the products of combustion flow downwardly therethrough, burner means in said main convector, a draft pipe for said products of combustion communicating with the lower end of said auxiliary convectors, a draft hood surrounding the upper end of said draft pipe and having an opening to atmosphere, an explosion relief passage for establishing communication between said draft hood and the upper end of said main convector, and a gravity closed gate for closing said passage.

In a furnace, a chambered main heat convector generally vertically disposed and adapted to have heated products of combustion flow upwardly therethrough, a plurality of chambered auxiliary heat convectors generally vertically disposed alongside said main convector and adapted to have the products of combustion flow downwardly therethrough, stack means communicating with the lower ends of said auxiliary heat convectors, burner means in said main convector, vent means outside of and adjacent said furnace, a direct explosion relief passage from the top of said central convector to said vent means, a normally closed explosion relief gate in said passage, and passages connecting said main and auxiliary convectors, said last named passages being of sufficiently large cross-section to permit ready relief of explosive pressure from said auxiliary convectors to said relief passage.

7. Furnace construction as in claim 2 and in which said closure means for said by-pass means is constructed to operate also as an explosion relief means.

8. In a furnace, a chambered main heat convector generally vertically disposed and adapted to have heated products of combustion fiow upwardly therethrough, a plurality of chambered auxiliary heat convectors generally vertically disposed alongside said main convector and adapted to have the products of combustion flow downwardly therethrough, burner means in said main convector, vent means outside of and adjacent said furnace, by-pass means for establishing communication between said vent means and the upper end of said main convector, a closure gate for said by-pass means hinged at the top to close by gravity, and a thermo-metal member adapted when cold' to change its shape and to engage said gate to open it.

9. A furnace as in claim 8 in which said thermometal member has one portion secured to said gate and another portion adapted to engage a stationary member when warped by reducing temperatures, and means for adjusting said stationary member to control the point at which said thermo-metal member opens said gate.

10. A furnace as in claim 3 including means for closing said draft hood opening to atmosphere by opening of said gate in said relief pas sage by explosion products passing therethrough.

OTTO J. KUENI-IOLD.

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