US1562737A - Hot-air heating system - Google Patents

Description

Nov. 24,1925.

D. A. BRUNETT HOT AIR HEATING SYSTEM 5 Sheet's-Sheet l Filed May 5, 1923 D. A. BRUNETT HOT AIR HEATING SYSTEM Filed May 5, 1923 Sheets-Sheet 2 Nov. 24 1925' D. A. BRUNETT HOT AIR HEATING SYSTEM Filed May 5, 1925 5 SheetsSheet 5 Nov. 24, 1925.

D. A. BRUNETT HOT AIR HEATING SYSTEM Filed May 5, 1923 5 Sheets-#Sheet 4 i. 0 T N E V N I Nov. 24,1925. 1,562,737

D. A. BRUNETT HOT AIR HEATING SYSTEM Filed May 5, 1923 5 Sheets-Sheet 5 u j j k Patented Nov. 24, 1925,

UNITED STATES DEWITT A. BRUNETT, OF MINNEAPOLIS, MINNESOTA.

HOT-AIR HE TING SYSTEM.

Application led May 3,

To all 'whom it may concern:

Be it known that I. Dnwrrr A. BnUNn'r'r, a citizen of the United States, residing at Minneapolis, in the county of Hennepm and State of Minnesota, have invent-ed certain new and useful Improvements in Hot-Air Heating Systems; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a warm air heat-- ing system and particularly to such a system including a furnace and a warm air auxiliary heating device in connection therewith. In warm air furnaces and auxiliary heating devices as heretofore constructed, there has often been a great deal of the heat from the fuel wasted by passing up the chimney and the warm air which is passed to the building to be heated has not been effectivelyv brought into contact with the heating surfaces containing the hot products of combustion.

It is an object of this invention, therefore, to provide an auxiliary heating device comprising a secondary combustion chamber having means connecting it to the combustion chamber of a furnace and having a passage for descending cold air around or at the exterior thereof and a plurality of passages for ascending warm air at the interior thereof.

It is also an object of the invention to so proportion the number and size of said passages for ascending warm air that the cross-sectional area thereof will have a definite rat-io to the grate area of the furnace and to the amount of heating surface with which the warm air comes in contact, whatever the size of the device.

Itis a further object of the invention to provide such a secondary combustion chamber, as stated, with a passage for descending cold air at the exterior thereof and a passage for warm air at the interior thereof, together with a skirt forming partition spaced slightly from the exterior wall of the secondary combustion chamber and forming a passage for ascendingvwarm air which conimunicates at its top with said first mentioned passage for ascending warm air.

It is still another object of the invention to provide a device having such a secondary combustion chamber as set forth which has means at one side Aand at the upper portion thereof connecting it to the combustion 1923. serial No. cae-414.

chamber of a furnace and which has a transverse partition adjacent its lower end eX- tending almost entirely around the same but having an opening therethrough 011 the opposite side of said secondary combustion chamber, which chamber also has an opening below said partitionl andat the first mentioned side thereof communicating with a smoke pipe.

It is also an object of the invention to provide a device having such a secondary combustion chamber as set forth, preferably of annular shape which may surround the combustion chamber ,of a furnace and which will then. have conduit-s connecting the same to the furnace below the grate bars thereof whereby the products of combustion from the primary combustion chamber of the furnace will descend in said secondary combustion chamber and be again circulated through the tire and the primary combustion chamber.

It is a still further object of the invention. to provide a device having such a secondary combustion chamber connected to the combustion chamber of a furnace adjacent its upper end and having at its lower portion a conduit connecting the same to a smoke pipe,

which smoke pipe has walls exposed to tho hot gaseous products of combustion in said secondary combustion chamber whereby the said gaseous products of combustion will descend in said secondary combustion chamber and will be cooled and will pass into said smoke pipe and then be re-heated by the walls of said smoke pipe being in contact with the hot gases in. said secondary combust-ion chamber. In this manner the heat necessary for draft purposes is transmitted to the gases passing through the chimney by radiation and the draft power of the gases due to the heat transmitted thereto will be proportional to the heat required in the heating system.

It is still another object of the invention to provide a device having a secondary combustion chamber and a smoke pipe in relation thereto, as above set forth, together with a damper-equipped passage opening into said smoke pipe at the upper portion of said secondary combustion chamber and, together with a damper disposed adjacent the lower end of said smoke pipe, which end communicates with the lower end of said secondary combustion chamber. i

These and other objects and advantages of the invention will be fully set forth in the following description made in connection with the accom anying drawings in which like reference c aracters refer to the.- same parts throughout the different views, and in which,

Fig. 1 is a vertical central section throuffh a `furnace having the auxiliary heating evice applied thereto;

Fig'. 2 is a central vertical sectionr through' said furnace taken in a plane at right angles to the section shown inA Fig. 1;

Fig. 3 is a horizontal section taken on the line 3-3 of Fig. 2, as indicatedvby the arrows;

Fig. 4 is a horizontal section taken on the line'4-4 of Fig. 2, as indicated by the arrows;

Fig. 5 is a partial horizontal section similar to that shown in Fig.- 3 but 'showing a modified form of the invention;

Fig. 6 is also a horizontal section similar to that shown in Fig. 3, but showing a further modified form of the invention;

Fig. 7 is a vertical central section through an auxiliary heating device formed as a separate unit from the furnace; and

Fig. 8 is a horizontal section taken on the line 8-8 of Fig. 7

Referring to the drawings, particularly Figs. 1 to 4, a. furnace is shown which may be of any desired type but which, in the embodiment of the invention illustrated, is shown as a hot air furnace. This furnace comprises a base member 1 shown as having a central circular flange at the inside thereof with which contacts an u standing cylinder 2 forming the ash pit o the furnace and which supports .at its upper edge a ring 3` which carries the grate bars 4. An upwardly flaring fire pot 5 is supported on ring 3 and extends upwardly therefrom having a grooved shoulder adjacent its upper edge adapted to support a cylindrical casing 6 having a closing top wall 7,'whieh casing forms the primary combustion chamber of the furnace. The base member 1 is provided with an outer upstanding flange at its upper side having secured thereto and upstanding therefrom the outer cylindrical shell or casing 8 which is secured at its upper end to a downwardly extending flange formed on a top plate 9 of the furnace, which plate is shown as extending slightly outwardly beyond the casing 8. An annular-casing 10 partially surrounds the casing 6, fire pot 5 and ash pit 2 and is spaced from the walls of said parts to form an annular assage 11. The chamber at theinterior o casing 1f? forms a secondary combustion chamber and is connected to the rimaryv 'combustion chamber formed by casing 6 by means coinprising the conduit 12. The casing 10, as shown in Figs. 3 and 4, terminates in end walls 13 at the front of the furnace and a short section of casing or curved member 14 1s secured to said end walls and extends around the front of the casing 6. At the rear of the furnace, the casing 1Q has its outer walls extending rearwardly in the portions 15 and has-an offset outer wall portion 16 connecting the portions 15. A transverse partition 17 shown as being disposed substantially' horizontal extends across the lower portion of the casing 10 for the greater part thereof and lterminates at each side of said casing in the ends 18 which are adjacent the end walls 13 of said casing. A smoke pipe 19 extends through the top of the easing 1U at the rear thereof between the wall portions 15 and projects downward in said casing through the partition 17 and. to a point adjacent the bottom of said casing, as clear-l",I shown in Fig. 1. The smoke pipe 19 is provided with a damper 20 adjacent its lower end operated by a rod 21 and arms 22, which latter has a handle extending to the outside i of the furnace (not shown). The smoke 'pipe 19 is also provided with an opening .opposite the conduit 12, which opening is closed lor opened more or less by means of a hinged damper r23 .having an operating.

handle-equipped arm 24 which extends to the exterior of the furnace, as shown in Fig. 1. The space between casings 6 and 10 forms a passage for ascending warm air and said space is dlvided into aplurality of pas`- l spaced relation to the wall 14, said double.

wall, however, being shown as terminating at the wall portions 15 of the casing 10. The upper portion of the walls -26 incline inwardly toward the center of the cover plate 9 and the inner one of said walls is provided with a plurality of apertures 27.

The furnace is provided with the usualv charging passage formed by the casing 28 extending through the front of walls 14 and 26 and through the outer shell 8 which latter is illustrated as being flat orextending in a plane at the front of the furnace. The said casing 28 has a fire door 29 hinged thereto provided with a draft opening 30 adjacent its lower edge opening into a space formed in the door by a vertical partition 31, which latter has a plurality of openings 32 extending therethrough. The cover 9 has a plurality of circumferentially.y arranged openings therethrough in which terminate the cou- Vsiderably wider than the casing 10.

duits 33 which lead to the rooms of the building` to be heated and each of which com passages 35 receive the warm air ascending to the rooms to be heated and these passages communicate with the passages formed between the partitions 25 and the casings 6 and 10. The ash pit formed by casing 2 is provided with a suitable ash door 36 hinged to the outer shell 8 and an o eratin mechanism including a square enlded roi? 37 and gears 38 are illustrated for operating the grate bars. The casing forming the ash pit is also connected to the lower portion of casing 10 by circumferentially spaced conduits 39.

The furnace is illustrated as `provided with a humidifying device which includesa U-shaped pipe or conduit 40 extending around the rear of the ash pit, which conduit has connected thereto the vertical pipes 41 opening at their upper ends. Water is supplied to t-he conduit 4() by a pipe 41 extending therefrom to the exterior of the shell 8 where it is connected with a water receiving receptacle 42 having a hinge cover 43 thereon, which receptacle, as shown in dotted lines in Fig. 2, is of less height thanl the pipes 41. The furnace is provided with a clean-out opening 44 for the casing 10 which normally is closed by a hinge gravity door 45.

In the modification shown in Fig. 5, the casing 6 is shown having the conduit 12 connecting the same to the annular casing 46 corresponding to the casing 10 in Figs. 1 to 4. The outer shell 8 is shown together with the clean-out passage 44 and door 45, which passage communicates with the casing 46. A single wall 47 corresponding to the double wall 26 passes around the exterior of casing 46 and the casing 46 is con- A smoke pipe 48 passes through the casing 46 in the same manner as the smoke pipe 19 passes through the casing 10. Circumferentially spaced semi-annular conduits extend through the casing 46, which latter casing forms the secondary combustion chamber and these conduits open at the upper and lower portions of the casing 10, thus communicating at the lower ends with a space between the casing 46 and the shell 8 and at their upper ends with the spaces between casing 46 and casing 6. Circular partition walls 50 extend between the conduits 49 and connect the same and the smoke pipe 48.

In the modification shown in Fig. 6, the casing 6 and conduit 12 leadingn therefrom are illustrated, together 'with the outer shell 8 and the cleanout casing and door 44 and 45, respectively. The secondary combustion chamber is formed by a casing 51 and a single wall partition 52 extends down around the exterior of casing 51, in the same manner as the double wall partition 26 extends around the casing 10. The cas* ing 51 has extending therethrough a smoke pipe 54 having the same relation thereto that the smoke pipe 19 has to the casing 10.

A plurality of cylindrical conduits 53 extend vertically entirely through the casing v51 having their open ends at the top and bottom walls thereof The lower ends of these conduits thus communicate with the space between wall 52 and shell 8 and the upper ends of said conduits communicate with the space between casing 51 and casing 6.

The auxiliary heat-ing device of this inventioncan also be employed as a unit separate from the furnace andsuch an embodiment of the invention is illustrated in Figs. 7 and 8. Referring to said figures, the auxiliary device comprises the base 55 and the top 56. The base has an annular flange projecting from the upper side thereof and secured thereto to which is secured the outer shell 57 which, at its upper end is secured to a flange projecting downwardly from the plate 56. The secondary combustion chamber is formed by an annular casing 58 disposed centrally in the shell 57, the central chamber through wliich,.is divided.

by a central partition 59. into separate passages 60 and 61. The casing 58 is connected to the combustion chamber of a furnace 67, a p-art of which is indicated in Fig. 8 by a conduit 68. The casing 58 also has an offset extension 69 adjacent its bottom on the side opposite the conduit 68 and a smoke pipe 70 extends upwardly through the casing 58 and through the top plate 56 and communicates with the chimney. .The smoke pipe 70 terminates adjacent the 'oottom of the casing 58 in the same manner as the smoke pipe 19 terminates near the bottom of casing 10, as shown in Fig. l and the smoke pipe 7 O will be provided with a suitable damper 80 such as shown at'2()v in Fig. 1. A door-equipped clean-out passage 71 is also provided adjacent the bottom of the shell 57 extending into the casing 58. The casing 58 is also provided with a cleaning device comprising a. member formed by rings 72 adapted substantially to fit against. the inside walls of casing 58, which rings are connected` by spaced bars or rods 73 to form a rigid frame. Flexible members 74' are connected to certain of the rods 73 and extend up through the casing 58 and into pipes 75 having curved bends, which pipes merge into a common pipe extending through the shell 57 and said flex- 'handle correspondingto the partitions '26 in- Figs.

j ly to 4 extends about the exterior of'casing 58 and is slightlyspaced therefrom, said partition extending almost to the bottom .e of casing 58. The vcover plate 56, like the plate 9 has a plurality of circumferentially l-arranged openings with which communicate the conduits 63 which lead to the r )oms of the buildings to be heated.

These conduits are each divided by a partition 64 to form -afpas'sage 65 for des"ending cold air andra passage 66 for ascendingr warm air and pas sages 65 communicate with the space between partition 62 and shell 57,' the partition G2 being co-ntinued upwardly 4to meet the partition 64. The passages 66 communicate with the passages 61 andGO which are for ascending` warm air. y

In operation of the device, as shown in Figs. 1 and 2, the furnace shown will be operated as usual with the fire carried in lire pot 5 on thegngrate 4. In starting the fire the damper 20 preferably will be closed and the damper `23 opened so as to get a direct and strong draft through the chimney. Af-A ter the fire is well started, the damper 23 is closed and the damper 20 opened to a greater or less degree. The hot gases of combustion pass from the primary combustion chamber formed in the casing 6 through the conduit 12 into the secondary combustionv chamber of casing 10. These gases ,pass downwardly through said casing and must pass around to the end portions 18 of partition 1 7. They then pass under said partition and aroundtothe rear of the casing 10 and can then enter the lower end of the smoke .pipe 19. `In their passage down through the casing 10 the gases are much cooled so that vpractically all of the available heat has been extracted therefrom. As the gases rise, however, insmoke pipe 19, they are again heated, ydue to the fact that the smoke pipe passes through the upper portion of casing 10 where the gases are quite hot and received directly from the primary combustion chamber. A sufficient amount of heat' is thus transmitted to the gases in smoke vthe burning fuel and this amount of heat will be regulated by adjustment of damper 20. 4The greater the amount of air allowed to pass out through the smoke pipe 19, the greater will be the combustion of fuel and the greater will be the amount of heat generated. As more heat is generated the smoke Jip@ 19 will heated to a. greater degree y the hot roducts of combustion and a corresponding ygreater draft will be created.

It will. thus bel seen that draft will -be created, as desired, and the furnace 'can be regulated to produce the necessary heat in all degrees of weather. The amount of surface Vnecessary to create the required heat for the draft. can be determined in the con struction ofthe furnace so that the proper draft will be created at all times. The heat for the draft is thus created by -radiation and it is more feasible and a great deal more eicient from a practical standpoint to extract the heat from the gases and then put back the necessary amountfor draft purposes than it is to attempt to regulate the.

heat going to the chimney direct. Another` '3f test and continually cooled and contracted resulted in great difficulty in properly reg-- ulating the draft.

It is desirable for the warm air furnace to have a humidifier and in the embodiment of the invention illustrated the water will be placed in the tank 42 and may be regulated therein from the city water supply by suitable controlling mechanism. The water will pass through the pipe 41n into pipe 40 and rise in the pipes 41to the level of the water in tank 42. The heat from the tire box and ash pit will evaporate sufficient water s0 that the vapor will pass out with the warm air. If for any reason the water control should get out of order, the water would first run out of tank 42 which is at a lower level than the pipes 41 so that the trouble would be discovered quickly and the furnace would not be flooded.

The auxiliary heating device, as stated, may also be formed as a separate unit, as shown in Figs. 7 and 8. The hot gases of combustion pass into the secondary combustion chamber or casing 58 and pass downwardly therethrough and into the lower end of the smoke pip-e 70. The gases will be cooled in their descent so that, as in the other `modification described, they will enter the bottom of the smoke pipe in substantially cooled condition and will be reheated as they pass upward therethrough. This, as above described, furnishes the necessary draft power. The cooled air from the rooms passes down between walls 62 and shell 57 and the bulk thereof then passes into the lOll passages and 61 where it is heated by the secondary combustion chamber 5.8 and passes out throu h the warm air .conduit 66. The partition 62 functions' similarly yto the partition 26 already described and causes the upward current of air adjacent thereto to travel oppositely to the downcoming heated products of combustion and this partition also presents excessive heating of the downcoming obviously the same as that of the auxiliary heater applied directly to the furnace.

The cold air returning from the building descends through the conduits 34 and down through the space between walls 26 and shell 8. The greater bulk of this air passes around the bottom of casing 10 and upwardly through the passages in the chamber 11 which are formed by the partitions 25. This air will thus be efficiently heated by contact with the `walls of the casings 6 and 10. In order to have theV currents of the products of combustion and the air to be heated traveling in opposite directions so that the cold lair comes first in contact with the coolest heating surfaces, the skirt formed by partitions 26 is provided. A portion of the cooled air thus passes between walls 26 and the casing 10 and this cold air will first come into contact with the cooler products of combustion and as it moves upwardly, will come successively in contact with the hotter gases of combustion. The air will thus be effectively heated. The provision of the skirt partition 26 besides giving a morev efficient heating operation for the warm air also prevents the descending cold air from absorbing too great an amount of heat lat the outer portion of the furnace. It is desirable to avoid this heating of the downcoming air as it merely results in excessive radiation into the basement containing the furnace and the consequent ineffective use or loss of heat. It is for this purpose that the wall 26 is made double so that it has a layer of insulating air therein. The holes 27 are provided so that there may be a very slight circulation of air between the walls 26 so that the insulating air therein will be kept at comparatively low temperature. When it is desired to carry a very low fire the air drafts of the furnace will be closed and the damper 20 also very nearly closed. The products of. combustion will then circulate down through the casing 10 and through the conduits'39 and will again be passed through the fire. This will result in a complete combustion of any of the unburned gases and just enough air will be admitted to the furnace to create sufficient draft to keep the fire going. The damper 2() and the hot draft regulating dampers at the front of the furnace can be automatically regulated by' a thermostat so that the necessary heat can be provided at all times to maintain the rooms to be heated at the desired temperature. The partitions 25 result in the air passing to the various hot air couduits 35 being equally heated so that one of said conduits cannot draw more heat from the furnace than another. It is' well known that the fire door of a furnace tends to becomeA quite hot especially when a deep lire is carried in the furnace. By the provision of the partition 31, in the fire door, an air space will be formed between the same and the outer wall of the door. The plate 31 will become quite heated and the "air passing in through the opening 30 adjacent the lower edge of the door will thus be heated as it passes upward in contact with plate 31 and will thus pass into the furnace in a heated condition. The air is thus in c0ndition to be more effectively burned and the outr wall of the re door is thus also kept coo It will be seen that with a large furnace unit, the cross-sectional area of the warm `air spaces between casings 6 and 10 will become quite large in proportion to the heating surface and the great area of the furnace. lt is desired therefore in the large units to provide extra heating surface for the warm air and this is d one by the modification illustrated in Figs. 5 and 6. In Fig. 5, the conduits 49 are passed through the secondary combustion chamber '46 and form additional passages for the ascend,

ing warm air or additional air heating passages. When these are used, the width of the secondary combustion chamber will be increased. The same idea is shown in Fig. 6 in which a great number of smaller conduits 53 are passed through the secondary combustion chamber and receive the cold air atfthe bottom thereof and deliver it to the warm lair passages at the top of the furnace. By providing these additional passages for the warm air the proper ratio can be maintained between the total cross sectional area of the warm air passages, the grate area of the furnace, and the heating surface with which the warm air contacts. This is very necessary in order to secure an efficient. heating of the air in `all sizes of installations.

It will thus be seen that applicant has provided a simple and eilcient form of hot air system comprising an auxiliary heating de vice. The heat from the products of combustion is` all elfectively used and the prody nace and excessive radiation into the base-` ment. The cost of the furnace is quite Vsmall owing to the large use of the sheet metal casings and the. 4furnace can be easily assembled and installed. I l

It will, of course, be understood, that various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of applicants invention, which, generally stated, consists in the matter shown andvdescribed and set forth in the appended claims.

What is claimed is: Y

1. An auxiliary heating device for a furnace comprising a casing forming avsecondary combustion chamber, means connecting said chamber to the primary combustion chamber of a furnace, a passage for descending cold air at the exterior'of said secondary combustion chamber, a passage for ascending warm air at the interior of said secondary combustion chamber and a skirt artitiolrbetween the exterior of said secon ary combustion chamber and said passage for descending cold air s aced a comparatively small distance from t e outerv Wall of said secondary combustion chamber to form a passage for ascending air communicating at its bottom with said passage for cold air and at its top with the said passage for ascending warm air.

2. The structure set forth in claim 1, and a plurality of conduits for ascending warm air assing through said secondary combustlon chamber communicating kat their lower ends with said passage for descending cold air andat their upper ends with said passa e for ascending Warm air.

3. in auxiliary heating device for a furnace comprising a casing forming a secondary combustion chamber, means adjacent the top portion thereof connecting the same to the combustion chamber of a-furnace,` said secondary combustion chamber having a passage near its bottom leading therefrom, and a smoke pipe to which said passage is connected having a portion thereof with a heat conducting wall-passing through said secondary combustion chamber whereby the gaseous products of combustion are cooled by their descent in said secondary combustion chamber and will be re-heated by their passage;l through the smoke pipe. auxiliary heating evice for a ondary combustion chamber, meansconnecting said chamber to the primary combustion chamber of a furnace, a passage for descending cold air at the exterior of Isaid secondary combustion chamber, a passage for ascending warm air at the interior of said secondary combustion chamber, and a plurality of spaced conduits for ascending warm air passing through said secondary combustionv chamber communicating at their lower ends with said passage for descending cold air and at their upper ends with said passage for ascending Warm air.

6. In combination with the fire pot, ashpit therebelow and the primary combustion chamber of a furnace, of a secondary combustion chamber embracing said primary combustion chamber, means at the upper portion of said latter chamber connecting the same to said primary combustion chamber, means connecting said secondary combustion chamber adjacent its bottom with said ashpit, whereby the gases of combus-- tion will be vcirculated through the fire producing the same.

7. The structure set forth in claim 6, a smoke pipe communicating with said secondary combustion chamber adjacent the bottom of the same, and means for controlling the passage of gases' into said smoke pipe.

8. An auxiliary heating device comprising a secondary combustion chamber, a smoke pipe communicating with the lower portion thereof, conduits leading to said ddevice from the rooms to be heated, a passage for descending cold air connected to certain of said conduits and disposed at the exterior of said secondary combustion chamber, a passage for ascending warm air connected to other of said conduits and disposed at the interior of said combustion chamber, and means connecting said seconda combustion chamber to the combustion c amber of a furnace.

9. An auxiliary heating device comprising a casing forminga chamber, means connecting said casing and chamber to the combustion chamber of a furnace, a casing within said first mentioned casing and forming a chamber having openings leading to the space to be heated, and a plurality of conduits leading from said last mentioned chamber disposed in and extending downwardly through said first mentioned chamber and having lower open ends for the entry of cold air whereby said air is heated as it passes upwardly therethrough.

10. An auxiliary heating device for a furnace comprising a casing havingr a secondary combustion chamber, means adjacent the top portion thereof connecting the same to the combustion chamber of a furnace, said chamber having an openingnear its bottom leading therefron'i. and a passage extending upwardly from said opening and connected to the chimney, said passage being at its upper portion 'adjacent said first mentioned means whereby the products from said eombustiou chamber of the furnace will heat the gases in said passage.

1l. An auxiliary heating device for a fur nace comprising' a lusing having a secondary combustion chaml'ier, means adjacent the top portion thereof connect-ing the sameto the combustion chamber of a furnace` said chamber having an opening near its bottom leading therefrom, and a passage extending upwardly from said opening` connected to the chimney and having the Wall thereof passing in front of said means, so that the gases in said passage may beheated by said first mentioned means.

In testimony whereof I aflix my signature.

DEWITT 4A. BRUNETT.

Images