US2625150A - Space heating hot-air furnace for house trailers and the like - Google Patents

Description

Jan. 13, 1953 E. E. LITTLE 2,@25,l50

SPACE HEATING HOT-AIR FURNACE FOR HOUSE TRAILERS AND THE LIKE Filed Feb. 23, 1949 Y 5 Sheets-Sheet l i g f i i l I 1 M B i 46 4 ii /2 if Mi Ii 4 l l 5:

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22 9 /0 20 23 Juventor I 3? I 5/4/0045 L/ff/e 8g Hi W. HIIIH HIHIHHIHL 4 45 Gttomegs Jan. 13, 1953 E. E. LITTLE SPACE HEATING HOT-AIR FURNACE FOR HOUSE TRAILERS AND THE LIKE 5 Sheets-Sheet 2 Filed Feb. 23, 1949 Zhwentor f7/liaac/ 51/2 attorneys Jan. 13, 1953 Filed Feb. 23, 1949 E. E. LITTLE SPACE HEATING HOT-AIR FURNACE FOR HOUSE TRAILERS AND THE LIKE 3 Sheets-Sheet 3 Zhwentor (Ittomegs Patented Jan. 13, 1953 SPACE HEATING HOT-AIR FURNACE FOR HOUSE TRAILERS AND THE LIKE Ellwood E. Little, Wichita, Kans., assignor to The Coleman Company, Inc., Wichita, Kans., a corporation of Kansas Application February 23, 1949, Serial No. 77,796

This invention relates to space heaters which heat by convection with the warmed air being used as the circulating medium and which are particularly adapted for heating small spaces such as the interior of house trailers.

It is well known that house trailers are difficult to heat because they are of relatively small cubic content and have low ceilings. Consequently as in all warm air space heating, the air tends to stratify, that is, the air from the heater expands and being lighter, collects at the ceiling and the cool air being heavier, settles to the floor. Thus, the heads of the occupants are in an exceptionally high heat zone while the feet are in a zone too cool for comfort. The temperature differential is often from 15 to 20 and this unhealthy condition of cold feet and overheated heads is universal in house trailers of today. This unhealthy condition is aggravated by the box-like structures of such trailers with the floor, roof and sides all exposed to outside -temperatures. Another disadvantage is that when the heaters are operated at suflicient- 1y high burning rate to supply the required heat in cold weather, they may become overheated and are likely to cause fire in the relatively limited space in which the heaters must be installed.

It is, therefore, the principal object of the present invention to create a substantially uniform temperature throughout all portions of the house trailer by providing a gravity flow air circulating heater with a power air circulator which when in operation will produce a reverse circulation of the major air flow by continuously drawing off the warm air that collects at the ceiling and forcing the air downwardly through the heater for added heat and then delivering the air into the cooler air at the floor. In this manner the differential temperatures in the living' space are nearly eliminated as the entire mass of air is caused to be blended and uniformly heated.

It is also an object of the invention to provide a heater which will operate successfullyunder natural gravity flow circulation to deliver a large A volume of warm air at the ceiling which falls to the floor as rapidly as the cooler air below is drawn off through the heater unit whereby ample heat is provided when electric current is not available for operating the forced air circulator. It is a further object of the invention to provide the power air circulator with means for bringing in a controlled portion of the air from outside of the space being heated so as to furnish an oxygen content for healthful brea-thing and good ventilation. without dangerous drafts of cold air and to reduce the relative humidity which prevents sweating of walls and frosted windows.

Further objects of the invention are to pro- 8 Claims. (01. 126-110) vide a structure which requires no manual or automatic controls when shifting from forced air circulation to natural gravity circulation as in the case of a current interruption or when the heater is started without forced circulation; and to provide a heater structure which operates safely and efficiently whether as an upfiow natural draft heater or a forced air flow heater when the built-in power circulator is energized.

Another object of the invention is to provide for operation of the air circulator in connection with a cooling unit when there is no fire in the heater, that is, the hot interior air caused. by sun exposure in the day time may be eliminated by forcing the cool night air into the trailer, or a conventional cooler unit may be attached to the outside air inlet for summer use.

Other objects of the invention are to provide a small, compact heater that is readily installed in the available space of a house trailer and which is designed so as to avoid over-heating of the relatively close surrounding surfaces and trailer furnishings; and to provide a heater construction wherein the air has a relatively long travel in contact with vertically extended heat-- ing surfaces so as to provide ample heat exchange area with a combustion chamber of relatively small transverse diameter.

In accomplishing these and other objects of the invention, I have provided improved structure, the preferred form of which is illustrated in the accompanying drawing wherein:

, Fig. l is a side elevational view of a heater constructed in accordance with the present invention, a part of the casing being broken away to better illustrate the construction.

Fig. 2 is a plan view.

Fig. 3 is a vertical section through the lower portion of the heater taken on line 3-3 of Fig. 5.

Fig. 4 is a vertical section on the line 44 of Fig. 2.

Fig. 5 is-ahorizontal section through the lower portion of the heater on the line 5-5 of Fig. 1.

Fig. 6 is a vertical section through the lower portion of the heater taken on the line 6-6 of Fig. 4.

Fig. '7 is a vertical section through a heater showing a modified form of construction.

Fig. 8 is a side elevatio-nal view of the heater shown in Fig. 7 with parts broken away and in section.

Refer-ring first to the construction illustrated in Figs. 1 to 6:

designates a heater especially designed for use in heating the interior space of a house trailer and which includes an outer casing 2 having relatively small width and depth to permit mounting in the relatively small space in which such heaters are installed. The casing, however, is of substantially elongated form and extends from the floor to near the ceiling of the trailer so as to obtain maximum travel of circulated air in contact with a relatively tall heating unit under pressure effected by an air circulator unit 3.

The casing 2 includes front and rear walls 45 and side walls 6-4 formed of suitable material. The top of the casing is closed by a cap 8 which carries the unit 3 as later described. The lower end of the casing is closed by a bottom 9 having support on the floor and which mounts a base 10 which carries a heating unit generally designated ii that extends perpendicular within the casing as shown in Fig. 2.

The heating unit includes a combustion chamber [2 of substantial length but of small diameter to provide ample space therearound for a circumferential partition member l3. The partition member I3 is supported on a horizontal partition i4 having an opening through which the lower portion of the heater extends. The partition extends upwardly and terminates below the cap 8 to cooperate with the walls of the outer casing and exterior surfaces of the heater unit to provide inner and outer vertical passageways Hi and H. The bottom of the passageway I! is closed by the horizontal partition l4 while the upper end is interconnected with the passageway 16 across the top of the partition 13 by a space [8 below the top 8.

The lower portion of the heating unit includes a relatively larger cylindrical portion [9 that is joined with the wall of the combustion chamber H to form a burner chamber 20. The base is spaced above the bottom 9 to provide an air passageway 2| having an air inlet opening 22 to supply combustion air through an opening 23 to a burner 24.

In the illustrated instance the burner 24 is of the pot type and is supported within the burner chamber by a suitable stand 25 that rests on the bottom 9. The burner pot seats a fire ring 26 through which products of combustion pass into the combustion chamber. The diameter of the burner chamber is such that the inner passageway [6 continues to the bottom 9 where it connects with an air duct 21 that is adapted to lead to a hard-to-heat portion of the trailer, for example, the bedroom or aremote end of the trailen The passageways l6 and I! also connect with the space above the floor of the trailer through louvers 2B and grilles 29 that are located in the side walls 6 and 1.

The upper portion of the combustion chamber is connected with a flue 30 that extends through an air duct- 3l, the flue being adapted to be connected to an outlet in the roof of the trailer (not shown). The duct 3| includes front, rear and side walls 32, 33, 34 and 34' that are closed about the flue 30 by a ring 35. The walls of the duct depend within the outer casing to a point below the terminal edge 36 of the partition 13 and surround a conical end of the combustion chamber or a conical cowl 3'1 surrounding the top of the combustion chamber to form an aspirating opening 38 for a purpose later described.

Connected with one of the side walls of the duct 3! is an air circulator comprising a blower 39 having a motor 3 for operating the impeller thereof. The blower has an outlet 40 that connects with the duct 3! as indicated in Fig. 1. Air is drawn into the blower through an opening 4! from adjacent the ceiling of the trailer to gather air from the ceiling and effect forced circulation thereof downwardly through the duct 3| and through the aspirating opening 38 into the space 4 16 to be heated by contact with the surfaces of the combustion chamber. The heated air is discharged under pressure at the bottom of the casing through the grille opening 29 and through the pipe connection 27 which leads to a hard-toheat point of the trailer.

This method of heating the air maintains very close floor and ceilin temperatures and avoids the unhealthy conditions as above noted, but when the house trailer is parked in locations where electricity is not available, it is necessary to provide gravity circulation so that the interior of the trailer may be heated. With gravity circulation it is necessary to provide an upward circulation of air through the space it, the air being admitted through the grille openings 29. Upon being heated the air expands and rises naturally to the top of the passageway where it is discharged over the top of the partition 53 for discharge into the interior of the trailer through louvered openings 52.

It is obvious for this method of circulation that a separate outlet must be provided for the rising column of air and for this reason it is necessary to leave the top of the passageway open, otherwise resistance to flow by the fan and contact of the heated air with the motor would render such method impractical. The open top of the passageway i=3 would render the forced circulation impractical since the resistance to downward flow around the combustion chamber would cause spilling of the air through the open top of the passageway, however, with the aspirating opening sufficient air is aspirated through the open tops of he passageways to overcome back pressure on the forced air flow with the result that all of the forced air passes dovmwardly through the passageway 58. The aspirated air is obtained by the natural circulation of air through the passageway i7 responsive to expansion of the air being heated therein by contact with the outer face of the partition l3. Since air is constantly being admitted to the lower end of the passageway l'l through the louver openings 28, constant circulation is maintained upwardly in the passageway H, the air not used and the air not aspirated being discharged through the louver openings 42. This flow of air through the passageway 17 is also maintained when the heater is operating under natural gravity circulation and forms an importantv function of carrying away heat from the partition 83 to avoid overheating the walls of the casing.

The burner may be supplied with fuel from a suitable tank 43 mounted on the back wall of the outer casing and which delivers fuel to an oil level and regulating valve 44 which is connected with the vaporizer pct type burner by a pipe 45.

To promote a fresh air condition within the trailer space and prevent burning up of the oxy gen in the-air as well as sweating and frosting of the windows, it is desirable to provide for admission of fresh air. This is eifected by a duct 46 that has an inlet 47 adapted to extend through an opening in the floor of the trailer and which rises alongside the rear wall to terminate in a laterally extending duct 48 dischargin into the air inlet opening of the blower. When the blower is in operation air is drawn through the supply duct 45 by the aspirating effect of the air drawn into the inlet opening of the blower under control of a damper 16.

Assuming that the heater is constructed and assembled as described within a trailer and that the burner 24 and blower 38 are in operation, air

is drawn through the inlet of the blower 39' and discharged downwardly through the housing- 31 in heatexchange relation with the flue 39 and around the walls of the combustion chamber to be heated thereby, the hot air being discharged near floor level through the grille 29 and duct connection 21. Simultaneously air is moving upwardly through the passageway I? by gravity circulation so as to avoid overheating of the walls of the outer casing by the heat accumulating in the partition l3.

During operation of the fan, fresh air is being supplied through the duct 45 so as to maintain good atmospheric conditions within the living space of the trailer and prevent burnin up of the oxygen in the air incidental to operation of the burner. During this method of circulation, air under pressure is prevented from escaping through the open top of the passageway l by the air that is aspirated downwardly therethrough. Any of the heated air that does escape through the louver openings 42 passes into the low pressure area surrounding the blower and is immediately drawn into the blower inlet. It is thus obvious that this air does not increase ceiling temperatures.

In case an electric supply is not available for actuating the motor of the blower, a natural circulation is maintained by air moving reversely through the air grilles 28 and 29 up through the spaces l6 and I! in heat exchange relation with the combustion chamber I 2 from where the heated air is discharged into the heating space of the trailer through the louvered openings 42.

In the form of the invention shown in Figs. 7 and 8 all parts are enclosed within an outer casing 49 having front, rear and sidewalls 50, 5|, 52 and 53, a bottom 54 and a top 55. Located in the casing is a heater unit 56 substantially conforming in construction to the heater unit previously described. The heater unit, like that of the first described form, is enclosed by a partition 51 spaced from the walls of the heater unit and from the casing to provide vertical passageways 58 and 59. The partition 51 terminates short of the top of the outer casing in encircling relation with the flue 60 that extends through the top 55 of the casing. Encircling the flu 60 is an air duct 6| having a depending annular flange encircling the flue 69 and providing an aspiratingv passageway 62 in connection with the passage way 59 as best shown in Fig. 7. The duct 6| is supplied with air that is drawn from the upper portion of the trailer space by a blower 63 contained within a housing 65', the blower'having an inlet duct 65 opening through the top 55 of the casing. The blower-has an outlet connection 66 with the air duct 6| so that the air drawn from near the ceiling of the trailer, by way of the duct 65, is discharged through the duct 6| and downwardly within the passageways 59 surrounding the heating unit whereby the air is heated and the heated air is discharged at the bottom of the casing near the floor through louvers 5'! located in opposite side walls of the casing. Fresh air is supplied to the blower housing through a duct 68 that leads upwardly through the floor of the trailer and connects with the blower housing as ill indicated at B9. The ducts 65 and 68 may be pro- When the blower is not in operation, a reverse natural gravity circulation is effected by air that passes into the casing near the floor through louver 10 located in opposite side walls of the casing from where the air passes upwardly along sides of the heater unit through the passageways 59 and is discharged over the top of the partition 5'! through louvers H located in the front and side walls 50, 52 and 53 of the casing. Si-

multaneously an air flow is also effected up the outer passageway 58 to carry away the heat that may pass by radiation to the partition 51. The natural circulation is shown by the dotted arrows and theforced air circulation by the solid arrows. When the blower is in operation, there i an induced fiow of air downwardly through the passageway 59 by the aspirating effect of the air discharged from the blower in substantially the same manner as in the first-described construction.

In the spring and fall the burner may be op erated at low heat during muggy weather and the dampers l5 and 16 adjusted so'that all of the air is taken in' from the outside and vpassed through the heater for drying purposes before discharge into the living space. In the latter form, the fuel supply tank I2 and constant level regulating valve 13 are located within the casing alongside of the fresh air supply duct and access is had therethrough through a door 14 located in the side wall 52 of the casing.

If desired adetachable cooling unit 18 may be attached to the inlet end of the duct 68 and the forced air circulator may be operated to air condition the interior of the trailer for summer use, or if desired the heat accumulated from the sun's rays during the day time may be eliminated by drawing in the cool night air. In both instances,

the damper 15 will be closed and the damper 16 opened.

From the foregoing it is obvious that I have provided a forced air type of heater which is especially adapted for use in connection with house trailers and by reason of the forced air circulation from the ceiling toward the floor. Consequently, the air in the trailer is maintained more nearly uniform, thereby avoiding the unhealthy cold conditions near the floor and heat at the ceiling. It is also obvious that when electric current is not available the heater functions satisfactorily by natural circulation, the circulation, however, being reverse to that of the forced air circulation.

' What I claim and desire to secure by Letters Patent is:

1. A heater including an upright'casing having side walls and a top, a partition having a closed'cross sectional figure and spaced inwardly from side walls of the casing and terminating short of said top for forming vertical inner and outer flew passageways within the casing. said casing having an opening in the upper por tion thereof in communication with the upper ends of both of said passageways and having openings in the lower portion in connection with the lower ends of said passageways for natural gravity circulation upwardly through both of said passageways, a heating unit within the inner flow passageway, and a blower having an inlet ,for air exteriorly of the upper portion of the ing spaced inwardly of the terminal of the partition to provide a space therebetween for connection with the outer flow passageway for effecting asperation of a part of the air flow from said outer flow passageway downwardly through the inner flow passageway when the blower is in operation.

2. A heater including an upright casing, means forming vertical inner and outer flow passageways within the casing interconnected at their upper ends, said casing having openings in the lower portion thereof in connection with lower ends of the inner and outer flow passageways and having an opening in the upper portion in communication with both of said passageways at their interconnected upper ends for natural gravity circulation of air upwardly through both passageways, a heating unit within the inner flow passageway to heat said air, a blower housing in the casing, an inlet duct connected with the blower housing and in communication with the exterior of the upper end of the casing, a discharge duct connected with the blower housing and having an outlet discharging downwardly into the upper end of the inner flow passageway, and a blower in the blower housing for discharging a jet of air into the inner passageway in reverse movement to the natural air flow, said duct outlet being of a size relatively to the means forming the inner passageway to provide a passage therebetween in communication with the outer flow passageway to provide an aspirating effect on the natural air flow from said outer flow passageway to cause downward movement of a part of the air flow into the inner passageway-responsive to said jet when the blower is c in operation.

3. A heater including an upright casing, means forming vertical inner and outer flow passageways within the casing interconnected at the upper ends thereof, said casing having openings in the lower portion of the casing in connection with the lower ends of the inner and outer flow passageways and having an opening in the upper portion in communication with both of said passageways at substantially the point of interconnection for natural gravity circulation upwardly through the casing, a heating unit within the inner flow passageway, a blower housing in the casing, an inlet duct connected with the blower housing and in communication with the exterior of the upper portion of the casing, a discharge duct connected with the blower housing and having an outlet discharging downwardly into the upper end of the inner flow passageway, a blower in the blower housing for discharging a jet through the discharge duct and into the inner passageway, said discharge duct outlet being of a size relatively to the means forming the inner passageway to provide a passage therebetween in communication with the outer flow passageway for efiecting asperation of a part of the natural air flow in said outer passageway by said jet and movement thereof downwardly through the inner flow passageway when the blower is in operation, and a fresh air inlet duct connected with the blower housing and extending downwardly of the casing for supplying fresh air to the air circulated downwardly through the inner flow passageway.

4. A heater including an upright casing, means forming vertical inner and outer flow passageways within the casing with said passageways being interconnected at their upper ends, said casing having openings in the upper and lower portions thereof in connection with said passageways with the upper of said openings being in connection with the upper ends of both inner and outer passageways for natural gravity circulation upwardly through the casing, a heating unit within the inner flow passageway, a blower housing in the casing, an inlet duct connected with the blower housing and in communication with the exterior of the upper portion of the casing, a discharge duct connected with the blower housing and having an outlet discharging downwardly into the upper end of the inner flow passageway for reversing air flow in the passageway, a blower in the housing, said duct outlet being of a size relatively to the means forming the inner passageway to provide a passageway therebetween in communication with the upper interconnection of the flow passageway for effecting asperation of a part of the natural air flow from said outer flow passageway downwardly of the inner flow passageway when the blower is in operation, a fresh air inlet duct connected with the blower housing and extending downwardly of the casing for supplying fresh air to the air circulated downwardly through the inner flow passageway, and dampers in the blower inlet and fresh air ducts for proportioning ratio of the fresh air and circulated air,

5. A heater including a vertically elongated casing having openings at upper and lower portions thereof, a heating unit within the casing, a vertical partition in the casing and surrounding the heating unit to cooperate with the casing and heating unit in forming inner and outer vertical flow passageways on respective sides of the partition and interconnected across the top of the partition, said lower ends of the inner and outer passageways being connected with the lower of the casing openings and their upper ends having common connection with the upper of the casings openings substantially at the interconnection of said passageways, an air duct having an outlet discharging downwardly into the upper end of the inner passageway and of smaller cross section than the space defined by said partition and spaced inwardly of the upper end of the partition to provide an aspenating passageway therebetween in connection with said outer passageway and with said open: ing in the upper portion of the casing, and a blower having an inlet exteriorly of the upper portion of the casing for drawing in air and having a discharge connection with said air duct for discharging the air through the outlet .of said duct in a jet downwardly through the inner passageway to said lower opening of the casing and to efiect movement of air through the asperating passageway and downwardly of the inner passageway when the blower is in operation.

6. A heater including a vertically elongated casing having openings at upper and lower portions thereof, a heating unit within the casing. a vertical partition in the casing and surrounding the heating unit to cooperate with the casing and heating unit in forming inner and outer vertical flow passageways on respective sides of the partition and interconnected across the top of the partition, said lower ends of the inner and outer passageways being connected with the lower of the casing openings and their upper ends having common connection with the upper of the casing openings substantially at the interconnection of said passageways, an air duct having an outlet discharging downwardly into the upper end of the inner passageway and of smaller cross section than the space defined by said partition and spaced inwardly of the upper end of the partition to provide an asperating passageway therebetween in connection with said outer passageway and with said opening in the upper portion of the casing, and a blower having upper and lower inlets exteriorly of the upper and lower portions of the casing for drawing in air and having a discharge connection with said air duct for discharging the air through the outlet of said duct in a jet downwardly through the inner passageway to said lower opening of the casing and to effect movement of air through the asperating passageway and downwardly of the inner passageway when the blower is in operation.

7. A heater including a vertically elongated casing having openings at upper and lower portions thereof, a heating unit within the casing, a vertical partition in the casing and surrounding the heating unit to cooperate with the casing and heating unit in forming inner and outer vertical flow passageways on respective sides of the partition and interconnected across the top of the partition, said lower ends of the inner and outer passageways being connected with the lower of the casing openings and their upper ends having common connection with the upper of the casing openings substantially at the interconnection of said passageways, an air duct having an outlet discharging downwardly into the upper end of the inner passageway and of smaller cross section than the space defined by said partition and spaced inwardly of the upper end of the partition to provide an asperating passageway therebetween in connection with said outer passageway and with said opening in the upper portion of the casing, a blower in a housing having upper and lower inlets exteriorly of the upper and lower portions of the casing for drawing in air from outside the casing and having a discharge connection with said air duct for discharging the air through the outlet of said duct in a jet downwardly through the inner passageway to said lower opening of the casing and to effect movement of air through the asperating passageway and downwardly of the inner passageway when the blower is in operation, and dampers in said inlets to the blower housing 'for controlling ratio of flow through the respective inlets.

8. A heater including a vertically elongated casing having openings at upper and lower portions thereof, a heating unit within the casing, a vertical partition in the casing and surrounding the heating unit to cooperate with the casing and heating unit in forming inner and outer vertical flow passageways on the respective sides of the partition, said passageways being in connection with each other at upper ends thereof and in connection with the upper opening of the casing, said heating unit being tapered upwardly and inwardly at the upper end of the partition to provide a funnel-shaped inlet to the inner passageway, an air duct having an outlet discharging downwardly into the funnel-shaped inlet and of smaller cross section than the space defined by said partition and spaced inwardly between the upper end of the partition and said tapered portion of the heating unit to provide an asperating passageway in connection with the outer passageway and surrounding the outlet of said duct, and a blower having an inlet exteriorly of the upper portion of the casing for drawing in air and having a discharge connection with said air duct for discharging said air through the outlet of said duct in a jet downwardly through the inner passageway to effect movement of air through the asperating passageway into the inner passageway when the blower is in operation, said passageways being connected with the lower of said housing openings for passage of air into the lower ends of the inner and outer passageway when the blower is not in operation and to allow discharge of air from the inner passageway when the blower is in operation.

ELLWOOD E. LITTLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 926,332 Hunt June 29 1909 1,169,448 Williams Jan. 25, 1916 2,370,181 Miller Feb. 27, 1945 2,457,818 Heiman Jan. 4, 1949 2,470,571 Miller May 17, 1949 2,478,069 Walter Aug. 2, 1949

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