US2586411A

US2586411A - Liquid fuel burner and control

Info

Publication number: US2586411A
Application number: US41297A
Authority: US
Inventors: John A Wilson
Original assignee: LENNOX FURNACE CO
Current assignee: LENNOX FURNACE CO
Priority date: 1948-07-29
Filing date: 1948-07-29
Publication date: 1952-02-19
Anticipated expiration: 1969-02-19

Description

1952 J. A. WILSON LIQUID FUEL BURNER AND CONTROL Filed July 29, 1948 4 Sheets-Sheet l Mk QM Feb. 19, 1952 w N 2,586,411

LIQUID FUEL BURNER AND CONTROL Filed July 29, 1948 4 Sheets-Sheet 2 JU%%JW 07/0 6 9 Feb. 19, 1952 J. A. WILSON 2,586,411

LIQUID FUEL BURNER AND CONTROL Filed July 29, 1948 4 Sheets-Sheet 3 lrunl mh.

AIR INLET 26 FIZOM FAN T0 POT on. CONDUIT 32 H\GH FIRE 27 A? FLOW INTERMED4 1\ TE Alrenow y 34 4 &l4@ 25 v 3 J7 J! PILQT FIR-E A112 now 9 5m Feb. 19, 1952 J. A. WILSON 2,586,411

LIQUID FUEL BURNER AND CONTROL Filed July 29, 1948 4 Sheets-Sheet 4 Z OIL VALVE OPEN- I l I I I AIR DAMPER THERMOSTAT c LO 5: o

WAEP ELEMENT V m mew nae 1 A": FLOW OPEN WARP ELI IENT IN P LOT POST O ?!LOT FHZE OPERATION HIGH FIRE OPERATION IL VALV PARTlAU-fi I SNUT- v )EEN ERGI'LED 'mennasvnw 0 I Patented Feb. 19 1 952 LIQUID F-UEL BURNER'AND CONTROL John A. Wilson, Columbus, Ohio,.assig-nor to The. Lennox Furnace 00., Marshalltown, Iowa, a.

corporation of Iowa Application July 29, 1948,.Serial No. 41,297

27 Claims. 1

This invention relates to aliquid hydro-carbon fuel burner and the control thereof. It particularly relates to liquid fuel, burners of the vaporizing or hydroxylating type.

commonly referred to as pot type burners.

The feeding and regulating, of liquid fuel and combustion air in a pot type burner is of paramount importance to obtain efllcient and clean burning of fuel. Such burners usually operate at two or more stages of combustion. The present invention is directedtoa burner which operates at a low or pilot stage and at a high stage of combustion. The invention is not limited to two stage operation in all of. its aspects, however.

Most burners of the vaporizing type include a,

pot which has a substantially flat bottom with a liquid fuel connection. entering near said bottom. The sides of the pot are perforated, at intervals from a point near the bottom to a point near the top to supply air for combustion. Just below the top of the pot, there is usually a ring of closely spaced holes which admit air for the final phase of combustion. Various rings and baflles are generally placed in the pot, which is ofany well known construction.

In operation, liquid fuel, such as oil, is admitted to the pot and is originally ignited by means of a taper. During the starting phase, the oil burns from the bottom of, the pot under theusual pilot ring until the rate of vaporization of the oil exceeds the amount of air being admitted to the section below the pilotring. The vaporized gases then rise through the pilot ring and mix with air coming in from the holesv at the upper section of the pot. Eventually the flame is entirely out of the pot itself and burns at the top thereof.

When the burner is operating on pilot stage, the fire. gradually drops back into the pot until it is burning entirely below the pilot ring. In this position, oil at a reduced rate is still admittedto the pot, and in many of the present conventional burners, it flows over the entire bottom area.

Such burners are t the heating season, it is objectionable in mild Such a wide distribution of oil over the pot bot- 1 tom makes it necessary to burn. at a, fairly high rate in order to maintain a clean, uniform flame and to maintain sufficient temperature on thepot bottom to vaporize the oil. This is one of the reasons that most conventional pot burners; do not maintain a satisfactory pilot flame.- unless five or six cubic centimeters of oil permi-nute are fed thereto. (Sixty-three cubic centimeters of oil per minute is equivalent to a rate of one gallon per hour.)

While the burning at a. high pilot, rate has no particular disadvantage during colder periods of weather, as thepilot flame alone is. sufiicientfto overheat the average small. home in which such burners are generally installed.

Air for combustion to this type of burner is usually suppliediby. a small continuously operated blower, althoughv some such burners use gravity air flow. In order to. maintain air for. combufi tion during the pilot stage and at the same time not overcool the pot, it is customary to reduce the air supplied during thepilot stage. period.

This is accomplished in at least two ways. One, is to opena dampen which allows part of, the-fan.

airto by-pass to atmosphere. Another is to reduce the motor speed by reducing th voltage supplied thereto.

The reduction of the volume of air supplied during the. pilot flame operation is usually from to The disadvantage of; this arrangement is that while the air uolume is somewhat reduced, it is still supplied to all of. the holes in. the pot and air is continuously passing through the upper section thereof, which results in chilling the pot. The chilling condition: reduces the temperature of the entire pot to the exent that when the oil is again supplied in larger quantities for high the operation, it does not immediately vaporize. This causes a; fu-rther chilling of the pot. bottom, Eventually the pot comes up to temperature when. the oil. properly vaporizes, but thereis an intermediate period between the pilot. and the high flame stages where the fire is smoky and liberates considerable, quantities of soot.

Another disadvantage. of; conventional. Pot burners is that whenea fairly high pilot flame is burning. near the not. bottom. he. oil inlet pi reaches a sufliciently high temperature to, cause oil to carbonize inside thev tube adjacent the Point where it enters theipot. To overcome such; acondition,. a, rod is generally placed withinthe; oil tube having a scraper on: its innerend and. a handle. on its outer end. It is necessary for; the user to operate this rod at fairly frequent intelfe vals to keep the oil tube open.

From the foregoing, itzis apparent that, most conventional pot burners have three. main. dif: ficulties which are: ('1) toov high a pilot. flame; (2) a smoky or dirty condition of flame. duringits transition from the pilot. to high fire and; back again to pilot; and (3) excessive temperature on the oil inlet tube which causes. carbonization of oil. and seriously restricts the flow of; fuelto the pot.

One of; the objects of; the,- invention is to pro-.- i e a bu nerntr l th neier which will,

overcome the aforesaid disadvantages of pot type burners.

It is also an object of the invention to supply air to the pilot only during pilot operation, so that the pot is not chilled and the pilot flame heats the pot bottom to a sufiiciently high temperature to rapidly vaporize the high fire oil rate when it is supplied to the pot.

It is another object of the invention to cool the oil inlet pipe during the pilot stage by circulating cooling air thereover.

It is an additional object of the invention to provided a pot burner and control in which the transition from the pilot stage to the high fire stage and vice-versa is accomplished rapidly and without objectionable smoke.

Another object of the invention is to provide a very low rate of oil delivery for the pilot flame, so that it will not overheat the house in mild weather.

It is another object of the invention to provide an improved no-air shutter safety control for a forced draft pot type burner.

It is a further object of the invention to provide 1 a novel control for a pot type burner to improve combustion of liquid fuel therein.

It is also an object of the invention to provide an improved air duct and damper control for a forced draft pot type burner.

With these and other objects in view, the invention consists in the construction, arrangement and combination of the various parts of my device whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in the claims and illustrated in the accompanying drawings, wherein:

Figure 1 is a vertical sectional view through the burner, only a portion of the pot being shown;

Figure 2 is a sectional view of the burner taken on line 22 of Figures 1 and 3;

Figure 3 is a horizontal cross sectional view of the air duct and control system;

Figure 4 is a perspective view of a portion of the air duct and the burner showing the construction of the no-air shutter, with parts of the duct broken away for the sake of clarity;

Figure 5 is an elevational view of the blower and control panel, with the front cover plate removed;

Figure 6 is a transparent perspective view of the air ducts and damper utilized in the burner, the damper being in the high fire position;

Figure 7 is a transparent perspective view of the air duct, looking down on the top thereof, with the shutter in an intermediate position;

Figure 8 is another transparent perspective view of the air ducts and illustrates the shutter in the pilot fire position;

Figure 9 is a partial side view of the furnace and exterior air duct, with parts broken away for the sake of clarity;

Figure 10 is a diagrammatic wiring diagram showing the control for the burner in the high fire position; and

Figure 11 is a diagrammatic wiring diagram of the control shown in the pilot fire position.

Referring specifically to the drawings for a detailed description of the invention, numeral ll designates an oil burner pot or hydroxylating chamber of any well known construction. The pot II is open at its top and is cylindrical in shape, having side walls l2, with a plurality of air holes l3 therein and a bottom [4. A pilot flame housing or chamber is shown at [5 and may be of any well-known construction, the

purpose of the housing being to confine the pilot flame and to supply pilot air to the fuel in a confined location to secure clean and complete combustion without cooling the entire pot. Pilot air is introduced into the pilot chamber through a short air inlet pipe 16 and liquid fuel is supplied to the bottom of the pot II at a location within pilot chamber l5 through an oil inlet pipe II. A front vertical wall of the furnace combustion chamber is shown at l8.

Air for combustion is supplied through a novel duct construction, a portion [9 of which is disposed outside the furnace wall 18, and a portion 2! of which is disposed in the combustion chamber within the Wall 18. A partition wall 22 divides the air duct into the two

portions

19 and 2|, said vertical partition having an opening 23 therein in which a hinged damper or shutter, generally indicated at 24-, is disposed.

As shown, for example, in Figures 6, 7 and 8, the air duct portions [9 and 2| are substantially rectangular in shape and a vertical partition 25 divides the duct portion 21 into two chambers 25a and 25b.

The portion l9 of the air duct is provided with a side wall 26 into which an air delivery conduit 21 opens. The air delivery conduit 21 is in communication with an electrically driven fan or blower 28 contained in a casing 29. Preferably the fan 28 operates continuously during the time the burner is being used. Another side wall 32 of duct portion I9 is provided with an opening 31 therein which is normally closed by a no-air shutter generally indicated at 33, for a purpose hereinafter described.

The oil pipe ll extends through the lower portion of chamber 25a and through an air aperture 34 in partition 22 which is somewhat larger in diameter than oil pipe 11 and which is disposed below duct portion l9. An air opening 30 is provided in the lower portion of chamber 251; and communicates directly with the combustion chamber.

As best shown in Figures 1, 2 and 3, the shutter 24 is provided with two vanes or wings disposed at an angle to each other and is pivotally supported on flanges 35 of a plate 40 which is secured to the front furnace wall I8. A bar of metal 31 is secured to the shutter 24 between the vanes, and pivot pins 36 engage the bar to pivotally support the shutter, nuts or other suitable means being provided for retaining the pivot pins 36 in place.

Also secured to one of the vanes of shutter 24 is a bracket provided with an upper car 38 and a lower ear 42. A rod 39 having a hook on its inner end is releasably secured in an opening in ear 38, the purpose of which is hereinafter described. A coil tension spring 4| is releasably secured at one end in an opening in ear 42 and is releasably secured at its other end to a substantially air tight vertical partition 45 welded to duct portion l9. Rod 39 extends through a small opening in partition 45. The spring 4| tends to maintain the shutter 24 in the position shown in Figure 4, since it is attached thereto on one side of the pivot points, which is the high fire position.

An insulating panel 46 is provided for mounting electrical equipment and is supported from partition 45 by studs 89 to which screws are secured. The panel 46 is provided with an opening 41 therein, through which rod 39 extends. The rod 39 terminates a short distance in front of panel 46.

A thermally operated warp bar assembly 49 is mounted on panel 46 and operates a pivoted extension or lever 48 which is in engagement at all times with the end of rod 39, due to the bias of spring 4|. Obviously, movement of warp bar extension 48 tov the left, as viewed in Figure 4, rotates shutter 24 about pivots 36, and disposes it in the dotted line position shown in Figure 4, which is the pilot fire air position, as will be explained. In other words, the shutter 24 closes an opening 231) on one side of partition 25 and opens an opening 23a on the other side of partition 25, or vice versa, depending on the demand for high or pilot fire operation. The partition 25 provides a stop for shutter 24 in either position. A stud with suitable nuts thereon, is mounted on the panel 45 and provides a stop for extension 48 in its outward movement.

As best shown in Figure 4, the no-air shutter 33 is pivotally supported on a plate 52 secured to side wall 32 of duct portion l9. The plate 52 has inturned ears 53 formed thereon, which provide journals for a shaft 56 for no-air shutter 33. The shutter 33 is formed with flanges 54 and rod 51 is secured to said flanges. The rod 51 extends through a kidney shaped hole 53 in panel 46 and through a similarly shaped hole 59 in partition 45. 1

A no-air switch, generally indicated at 6|, 15 mounted on the front of the insulating panel 46 and includes a relatively fixed flexible contact arm 62 and a flexible contact arm 63, which is adapted to be moved by an enlarged end 57a. of rod 51, which extends a short distance in front of panel 46 into engagement with the under side of contact arm 63. The end 5111 of rod 57 travels in an arc and reaches its highest point approximately when the shutter 55 is closed.

Contacts

64 and 65 are provided on

contact arms

62 and 63, respectively.

Referring now to Figures and 11, the oil burner control includes a transformer having a. primary coil 66 and a secondary coil 61 to reduce a 110 volt line to 24 volts, for example. A limit switch 66, of any well known construction, is shown in the 110 volt circuit, so that if excessive temperatures are produced by the burner, the entire system, except the blower, will be rendered inactive. The control also includes a room thermostat diagrammatically illustrated at 69 and an oil valve .at ll. The oil valve is preferably electrically operated and is controlled by a warp relay switch generally indicated at 13, which also controls the operation of warp switch 49. The warp relay 13 includes a thermostatic warp bar and an electrical heater 14. The warp bar is provided with an extension 80 on which contacts 16 and T! are carried, which contacts are adapted to engage respectively with fixed contacts 18 and 79 mounted on panel 46, in positions which are not shown.

The oil valve H is of any standard type utilized with pot type burners. The valve never entirely prevents the flow of fuel to the vaporizing pot When the thermostat 69 is not calling for heat, the valve ll permits sufficient fuel to flow through pipe IT to maintain the desired low pilot flame. When the room thermostat calls for heat, the oil valve opens completely and permits sufficient flow of fuel through pipe I! to maintain the desired high flame The warp element 49 includes an electrical heater 82 and a thermostatic warp bar 83. The aforementioned arm 48, which engages with rod 6. 39 to operate shutter 24, is pivoted to a bracket 86 mounted on panel 46.

Suitable terminals 84a. for the oil valve, transformer and room thermostat are disposed on the panel 46. A cover plate 85 is provided to enclosethe panel 46. Screws 96 may be removed for gaining access to the electrical panel 46.

Angles 9| are secured to the front plate 40, which front plate is secured to the front furnace wall N! by studs and nuts 92. Screws 93 secure the air duct portion 1 9 to the angles 9|. Furnace studs 94 secure the front wall l8 of the furnace to the remainder thereof. The internal air duct portion 2| is preferably welded to the wall I8, and the inclined wall 20 thereof, through which the pilot air pipe |6 extends, is preferably screwed to. the remainder of duct portion 2|.

It is obvious, therefore, that the entire air duct and control assembly are made up of several independent readily detachable units so that. if it is necessary to repair or replace parts, there is no problem of assembly and disassembly. Such construction is also of advantage in manufacturing on a mass production basis, as the complete units may be brought into a main assembly line and may also be stocked. For example, the electrical panel 46 is readily accessible by removing the screws and taking off the front cover plate 85. The electrical panel itself may be removed by unscrewing screws in the studs 89 and removing wires from the terminals 84a. It will be noted that the

rods

39 and 51 do not interfere with removal of panel 46, because they extend freely through the holes therein.

If it is desired to remove the entire air duct portion I9, including shutter 24, nuts 92 are removed and the entire unit may be taken on the furnace. After the rod 39 is released from ear '38, and spring 4| from ear 42, the air duct portion l9 may be disassembled by removing screws 93. It is possible to reach ears 38 and 42through' opening 23 in plate 40. This plate 46 is shown as partition 22 in Figures 6, 7 and 8, which are merely diagrammatic.

If the entire assembly is to be removed, furnace studs 94 are unscrewed, and the entire unit may be moved forwardly, since the air pipe 16 and oil pipe extend freely through wall 20.

Clearly the reverse of the above is followed in assembling any of the 'componentparts of the air duct and control. Also, the fan 26 and its casing 29 and duct 21 may be readily removed as a unit by removing screw 91.

Operation The completely assembled burner operates in the following manner. Assuming that the line Ll, L2 is connected to a source of power, it is. obvious that the fan, which is preferably driven by an alternating current volt motor, operates continuously, regardless of the condition of the remainder of the circuit or apparatus. Leads I06 and HH connect the fan motor to line Ll, L2. Thus, combustion air is. continuously supplied during the entire heating season." Furthermore, the primary and secondary coils 66 and '61 of the transformer are energized continuously, unless the limit control, shown diagrammatically at 69, breaks the circuit because of excessive heat due to combustion.

Placing the limit switch 68 in the circuit to the primary 66 of the transformer provides a safety factor if, for some accidental reason, the

pilot flame is extinguished. If this occurs, the entire pot bottom may flood with 'oil, and if the user again starts the .burnerwithout first drain ing the pot, excessive temperatures may develop. As will be seen as the description progresses, if the limit switch operates, the damper 24 is positioned on high fire very quickly, if it is not already there, and the oil supply is not increased to the high fire rate as electric valve actuator I2 is deenergized. If the limit switch 68 then cycles, because room thermostat 69 is calling for heat, the oil valve II will also cycle between pilot fire and high fire operation, but the air flow remains high. The pot does not, however, have suflicient time to cool down to a point where the oil does not vaporize rapidly when high fire operation is initiated. It may be noted that under normal conditions, the limit switch will very seldom function, if at all. It is urely a safety device for protection from abnormal conditions.

Since the fan 28 operates continuously, the velocity of the combustion air maintains the no-air shutter 33 in the closed position at all times, as shown diagrammatically in Figures 10 and 11. The outlet from fan 28 is disposed directly opposite the no-air shutter in air duct portion I9 for this purpose. Contacts 64 and 55 are, therefore, maintained closed because rod 51 secured to no-air shutter 33 raises switch arm 63 to close said contacts. Obviously, if

contacts

64, 65 are opened because no air or insufficient air is being supplied by fan 28 for any reason, such as a burned out motor or low voltage, no energy is supplied to the 24 volt circuit. The oil valve II will then go to or remain on pilot fire operation and shutter 24 will go to or remain in high fire position, as will be clear as the description proceeds. If the fan is completely inactive, gravity air flow through the no-air shutter opening 3I and through opening 30 will be supplied to the combustion chamber. Air will be supplied in small amounts through opening 34 and. air inlet pipe I0. This gravity flow of air is suificient to maintain the pilot flame and to consume any oil in the pot at the time of blower failure. This again is purely a safety factor and takes care of an exceptional abnormal condition. When no air shutter is open, the control circuit is dead and the thermostat cannot open the oil valve. Again, such a condition would ordinarily seldom, if ever, occur during the life of the apparatus, since small motors of this type very infrequently fail if given normal care, and very low voltage conditions or interruptions of power supply are exceptional.

Assuming now that the limit switch 68 is closed, that the fan 28 is operating properly, and that the room thermostat 69 is not calling for heat, the apparatus will be in the condition shown in Figure 11, with room thermostat contacts I02 and I03 open and no-air contacts 04, 85 closed. The heater I4 of the relay switch I3 is deenergized, and warp bar I5 is cold. Contacts I6, I8 of relay switch I3 are, therefore, closed, and contacts 11 and I9 are open. Electric valve actuator '12 of oil valve II is deenergizeol, and oil valve II is supplying a reduced pilot flame fuel supply. Heater 82 of switch 48 is, therefore, energized and warp bar 83 is hot, thus moving the warp bar extension 84 to the right as viewed in Figure 3, and swinging arm 48 to the left about the pivot of bracket 86. The rod 39 is, therefore, pushed inwardly and damper or shutter 24 is rotated to the pilot position shown in dotted lines in Figure 3 and shown in full lines in Figure 11. Combustion air from fan 28 then enters air duct portion I9, passes through opening 23a in partition 22, into chamber 25a, and thence through pilot air pipe IE into pilot flame chamber I5. Excess air supplied to chamber 25a is directed to atmosphere through opening 34. It will be noted that oil pipe I1 is cooled by surplus air passing thereover when the burner is operating at the pilot stage. Due to the reduced flow of oil at this .time, carbonization may occur, but by cooling the oil pipe [1, such carbonization is effectively retarded. On high fire, cooling of the oil pipe I! is not essential, as the flame is burning from the top of the pot I I and the temperature adjacent the pilot chamber I5 and inlet of oil tube or pipe I1 is lower than on pilot flame.

Assuming now that the room thermostat calls for heat, thermostat contacts I02, I03 close and the burner goes on high fire operation, as shown in Figures 3 and 10, in the following manner. Closing of room thermostat contacts I02, I03 energizes heater I4 of relay switch I3. Shortly after, warp .bar I5 begins to move to the right, as viewed in Figure 11 and contacts I'B, I8 open. This immediately deenergizes heater 82 of warp switch 40, and as warp bar 83 cools fairly rapidly, it moves to the left as viewed in Figure 3, and arm 48 moves to the right, because spring 4| pushes rod 39 against arm 48. Shutter 24, therefore, moves to the high fire position shown in full lines in Figures 3 and 10 within a relatively short period of time and before warp bar I5 of relay switch I3 has closed contacts II, I9. Full combustion air flow is thus supplied to the pot I I before the high fuel rate for high fire is delivered thereto. The combustion air from fan 28 now enters chamber I9, passes through opening 23b into chamber 251), and thence into the pot II through opening 30 in the air duct and holes I3 in the pot. By supplying combustion air at a high rate prior to supplying fuel at a high rate, sufiicient air to support combustion of the increased fuel supply is insured and no smoke or soot is produced during the transition period.

The warp bar I5 of relay switch I3 continues to move, and shortly after damper or shutter 24 is in the high fire position, contacts TI, I9 are closed, thus energizing electric valve actuator I2 and opening oil valve II to supply a high oil rate to pot II through oil pipe II.

When room thermostat 69 is satisfied, contacts I02, I03 open and immediately deenergize heater I4 of relay switch I3. Wrap bar I5 cools fairly quickly and, shortly after contacts I02, I03 were opened, contacts 11, I9 open, thus deenergizing electric oil valve actuator I2 and partially shutting oil valve I I, so that pilot fiow of fuel is supplied to pot II through oil pipe II. However, shutter 24 remains in the high fire position for about 1 /2 to 2 minutes to completely burn residual fuel and to provide scavenging of the combustion space. The formation of soot or smoke during the transition period from high to pilot stage is, therefore, prevented. The delay in moving shutter 24 to pilot position is effected because a time interval occurs while warp bar I5 cools sufficiently to close contacts I6, I8 to energize heater 32 of switch 49. Thereafter, another time. interval occurs while warp .bar 83 of switch 49 flexes a sufiicient distance to rotate shutter 24 completely to the pilot position. The shutter 24 obviously passes through a plurality of intermediate positions between high and pilot fire, and vice versa, one of which is shown in Figure 7.

From the foregoing, it will be clear that, if for any reason the limit switch 68 operates or the

noair contacts

64, 65 open, the oil valve goes on pilot operation, because electric oil valve I2 is deenergized. Also, relay switch heater I4 is deenergized and heater 82 of switch 49 cannot be energized under such circumstances, even though room thermos-tat 68 calls for heat. Shutter or damper 24, therefore, assumes or remains in the high fire position, depending on the condition of the circuit when no-

air contacts

64, 65 open, or the limit switch 68 operates to break the transformer circuit.

The burner and control described above overcomes the inherent defects of most conventional pot burners, for the following reasons;

By preventing a high rate of delivery of combustion air to the pot during the pilot stage, and supplying air to the pilot only, the pot is not chilled and the pilot flame heats the pot bottom to a sufflciently high temperature (above 500 F.) to rapidly vaporize the high fire oil rate when it is delivered to the pot.

By circulating cooling air over the oil inlet pipe during the pilot stage, its temperature is maintained sufliciently low at all times to retard carbonization.

The burner herein described cycles between high and pilot stages without danger or the production of smoke or soot.

A dependable oil pilot rate as low as 1% cubic centimeters per minute may be maintained. One cubic centimeter of oil contains approximately 37 B. t. u., so that the heat input would be 55 B. t. u. per minute or 3300 B. t. u. per hour. One

gallon of oil would supply the pilot flame for about 42 hours. Such a rate does not cause discomfort during mild weather.

The burner and control is extremely safe in operation, is easy to construct, assemble, install, and repair, and is inexpensive to manufacture.

Some changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope without sacrificing any of the advantages thereof.

I claim as my invention:

1. Control apparatus for the pot type liquid fuel burners including a pot and a housing form ing a pilot flame chamber disposed therein, said control apparatus including a control panel, a fuel supply means having its outlet adapted to communicate with the pot adjacent the pilot flame chamber, means adapted to increase the flow of fuel to said pot upon a demand for heat and to decrease it when said demand is satisfied, means adapted to supply combustion air to burn said fuel, means adapted to increase the flow of combustion air to said pot upon a demand for heat and adapted to direct a decreased flow of air to said pilot chamber and substantially exclude air to said pot otherwise when the demand for heat is satisfied, said last means including a thermostatically responsive warp bar mounted on said panel, means for controlling the heating of the warp bar in response to heat demand, an air damper, means whereby said air damper controls the air flow, and means extending through said panel and movable by said warp bar for controlling the position of said damper to supply said increased or decreased air flow.

2. Control apparatus as set forth in claim 1 wherein the means for supplying combustion air comprises a continuously operating single speed blower.

3. Control apparatus as set forth in claim 1 wherein the means for supplying combustion ai comprises a continuously operating single speed blower and wherein means responsive to abnormal operation of said blower is provided to immediately decrease said fuel supply.

4. Control apparatus as set forth in claim 1 wherein the means for supplying combustion air comprises a continuously operating single speed blower and wherein means responsive to abnormal operation of said blower is provided to immediately decrease said fuel supply and to move said air damper to the position wherein it would normally increase the flow of combustion air to said pot.

5. Control apparatus for pot type liquid fuel burners including a pot, a housing forming ,a pilot flame chamber disposed therein and a fuel supply means adapted to have its outlet adjacent said pilot flame chamber, said control apparatus including means adapted to increase the flow of fuel to said pot upon a demand for heat and to decrease it when said demand is satisfied, means adapted to supply combustion air to burn said fuel comprising a continuously operating blower adapted to deliver combustion air at a constant volume and pressure, means adapted to increase the flow of combustion air to said pot upon a demand for heat and adapted to direct a decreased flow of air to said pilot chamber and substantially exclude air to said pot otherwise when said demand for heat is satisfied, said last means including firstly a divided air duct having one portion thereof adapted to communicate with said pilot chamber and with the atmosphere and the other portion thereof adapted to communicate with the pot proper, secondly a damper adapted to direct combustion air into one or the other duct portions, and thirdly means for operating the damper in response to the requirements for heat, and means adapted to immediately decrease the supply of fuel to the burner and to move said damper to the position wherein it normally effects maximum air flow to said burner upon a predetermined abnormal decrease in the supply of combustion air to said blower.

6. Control apparatus for pot type liquid fuel burners including a pot and a housing forming a pilot flame chamber disposed therein, said control apparatus including a control panel, a fuel supply means having its outlet adapted to communicate with the pot adjacent said pilot flame chamber, means adapted to increase the flow of fuel to said pot upon a demand for heat and to decrease it when said demand is satisfied, a continuously operating blower adapted to supply combustion air, means adapted to increase the flow of combustion air to said pot upon a demand for heat and adapted to direct a decreased flow of air to said pilot chamber and substantially exclude air to said pot otherwise when the demand for heat is satisfied, said last means including a movable damper, a thermostatically responsive warp bar mounted on said panel, means extending through said panel operated by said warp bar to move said damper, an electrical heater for said warp bar and a circuit including said heater for controlling the operation of said warp bar in response to requirements for heat.

7. Control apparatus for pot type liquid fuel burners including a pot and a housing forming a pilot flame chamber disposed therein, said control apparatus including a control panel, a fuel supply means having its outlet adapted to communicate with the pot adjacent said pilot flame chamber, means adapted to increase the flowof fuel to said pot upon a demand for heat and to decrease it when said demand is satisfied, a continuously operating blower adapted to supply combustion air, means adapted to increase the fiow of combustion air to said pot upon a demand for heat and adapted to direct a decreased flow of air to said pilot chamber and substantially exclude air to said pot otherwise when the demand for heat is satisfied, said last means including firstly a movable damper, secondly a thermostatically responsive warp bar mounted on said panel, thirdly means extending through said panel and moved by said warp bar to in turn move said damper, and fourthly a divided air duct including two passages, one of which is adapted to communicate at its outlet with said pilot chamber and the atmosphere and the other of which is adapted to communicate at its outletwith the area adjacent said pot proper, means for controlling the heating of the warp bar in response to heat demand, said passages also having inlets to receive air from said blower, and said damper being movable to substantially prevent the fiow of air through one or the other of said inlets.

8. Control apparatus for pot type liquid fuel burners including a pot, a housing forming a pilot flame chamber disposed therein and a fuel supply means having its outlet adjacent said pilot flame chamber, said control apparatus including means adapted to increase the flow of fuel to said pot upon a demand for heat and to decreasethe fiow of fuel when said demand is satisfied, means adapted to supply combustion air to burn said fuel, thermostatically controlled means adapted to increase the flow of combustion air to said pot upon a demand for heat, and adapted to direct a decreased flow of air to said pilot chamber and to substantially exclude air to said pot when said demand for heat is satisfied, said last means including a divided air duct having one portionthereof adapted to communicate with said pilot chamber and the other portion thereof adapted to communicate with said pot proper, a damper for directing combustion air into one or the other duct portions, and means for operating said damper in response to requirements for heat.

9. Control apparatus for pot type liquid fuel burners including a pot, a housing forming a pilot flame chamber disposed therein and a fuel supply means having its outlet adjacent said pilot flame chamber, said control apparatus including means adapted to increase the flow of fuel to said pot upon a demand for heat and to decrease the flow of fuel when said demand is satisfied, means adapted to supply combustion air to burn said fuel, thermostatically controlled means adapted to increase the flow of combustion air to said pot upon a demand for heat, and adapted to direct a decreased flow of air to said pilot chamber and to substantially exclude air to said not when said demand for heat is satisfied, said last means including a divided air duct having one portion thereof adapted to communicate with said pilot chamber and the other portion thereof adapted to communicate with said pot proper, a damper for directing combustion air into one or the other duct portions and means for operating said damper in response to the requirements for heat, a portion of said fuel supply means adjacent its outlet being disposed in the portion of said duct communicating with said pilot chamber.

10. Control apparatus for pot type liquid fuel burners including a pot, a housing forming a pilot fiame chamber disposed therein and a fuel supply means having its outlet adjacent said pilot flame chamber, said control apparatus including means adapted to increase the flow of fuel to said pot upon a demand for heat and to decrease the flow of fuel when said demand is satisfied, means adapted to sup-ply combustion air to burn said fuel comprising a continuously operating blower adapted to deliver combustion air at a constant volume and pressure, means adapted to increase the flow of combustion air to said pot upon a demand for heat, and adapted to direct a decreased flow of air to said pilot chamber and to substantially exclude air to said pot when said demand for heat is satisfied, said last means including a divided air duct having one portion thereof adapted to communicate with said pilot chamber and the other portion thereof adapted to communicate with said pot proper, a damper for directing combustion air into one or the other duct portions, and means for operating said damper in response to requirements for heat.

11. Control apparatus for pot type liquid fuel burners including a pot, a housing forming a pilot flame chamber disposed therein and a fuel supply means having its outlet adjacent said pilot flame chamber, said control apparatus including means adapted to increase the flow of fuel to said pot upon a demand for heat and to decrease the flow of fuel when said demand is satisfied, means adapted to supply combustion air to burn said fuel comprising a continuously operating blower adapted to deliver combustion air at a constant volume and pressure, means adapted to increase the flow of combustion air to said pot upon a demand for heat, and adapted to direct a decreased flow of air to said pilot chamber and to substantially exclude air to said pot when said demand for heat is satisfied, said last means including a divided air duct having one portion thereof adapted to communicate with said pilot chamber and with the atmosphere and the other portion thereof adapted to communicate with the pot proper, a damper for directing combustion air into one or the other duct portions, and means for operating the damper in response to the requirements for heat.

12. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases.

13. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said first chamb'er having an opening therein, and a shutter for closing said opening when said blower delivers a sufficient amount of air.

14. Control apparatus for pot type burnersincluding a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a condut for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a, first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said third chamber being adapted to accommodate said oil conduit.

15. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said third chamber being adapted to acccmmodate said oil conduit and extending through the outlet therein to the atmosphere.

16. Control apparatus for pot type burners including av pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber,-a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said. first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said third chamber being adapted to accommodate said oil conduit and extending through the outlet therein to atmosphere, said second and third chambers being disposed side by side with a partition therebetween.

1'7. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said third chamber being adapted to accommodate said oil conduit and extending through the outlet therein to atmosphere, said second and third chambers being disposed side by side with a partition therebetween, and said first chamber being disposed in a substantially horizontal alignment with said second and third chamber.

18. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit forsu'pplying oil to said pot, a continuously operating blower adapted to supply air, on air duct assembly, a moveable damper in the air duct assembly,

said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, and a removable control panel disposed in front of said first chamber, said means responsive to heat requirements being at least partially supported on said control panel.

19. Control apparatus for pot type burners including a pot and a housing forming a, pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a moveable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said air duct assembly adapted to be detachably secured to a wall forming said combustion chamber.

20. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat re quirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said air duct assembly and damper adapted to be 16 detchably secured as a unit to a wall forming said combustion chamber.

21. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said air duct assembly, said damper and at least a portion of said means responsive to said requirements adapted to be detachably secured as a unit to a wall forming said combustion chamber.

22. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a, conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said dam'per being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said first chamber and said damper adapted to be detachably secured as a unit to a wall forming said combustion chamber.

23. Control apparatus for not type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said first chamber adapted to be disposed outside said combustion chamber and said second and third chambers adapted to .be disposed within the combustion chamber.

24. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber havin an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said first chamber adapted to be disposed outside said combustion chamber and said second and third chambers adapted to be disposed within the combustion chamber, said first chamber and damper adapted to be detachably secured as a unit to said second and'third chamuers.

25. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said first chamber adapted to be disposed outside said combustion chamber and said second and third chambers adapted to be disposed within the combustion chamber, said first chamber and damper adapted to be detachably secured as a unit to said second and third chambers and an electrical panel supporting at least part of said means responsive to heat requirements and adapted to be supported by and removable with said first chamber.

26. Control apparatus for pot type burners including a pot and a housing forming a pilot chamber disposed therein, said pot being disposed in a combustion chamber, and a conduit for supplying oil to said pot, a continuously operating blower adapted to supply air, an air duct assembly, a movable damper in the air duct assembly, said air duct assembly including a first chamber into which said fan discharges, a second chamber having an outlet adapted to communicate with said combustion chamber and an inlet adapted to communicate with said first chamber, a third chamber having one outlet adapted to communicate with said pilot chamber, another outlet adapted to communicate with the atmosphere and an inlet also adapted to communicate with said first chamber, said damper being movable to close one of said inlets and open the other and vice versa and means responsive to heat requirements for moving said damper to open the inlet between the first and second chambers and to close the inlet between the first and third chambers when additional heat is required and to close the inlet between the first and third chambers when the requirement for heat decreases, said first chamber adapted to be disposed outside said combustion chamber and said second and third chambers adapted to be disposed within the combustion chamber, said I first chamber and damper adapted to be detachably secured as a unit to said second and third chambers and an electrical panel supporting at least part of said means responsive to heat requirements and removable with said first chamber, and a removable cover plate for said panel.

27. Control apparatus for pot type liquid fuel burners including a pot, a housing forming a pilot flame chamber disposed therein, and a fuel supply means having its outlet adjacent said pilot I flame chamber, said control apparatus including means adapted to increase the flow of fuel to said pot upon a demand for heat and to decrease it when said demand is satisfied, means adapted to supply combustion air to burn said fuel, a divided air duct having one portion thereof adapted to communicate with said pilot chamber and the other portion thereof adapted to communicate with said pot proper, a damper in said air duct arranged to increase and decrease the flow of air to the pot proper and to respectively decrease and increase the flow of air to the pilot chamber, and meansfor operating said damper in response to the requirements for heat.

JOHN A. WILSON.

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

UNITED STATES PATENTS Number Name Date 1,633,502 Staley June 21, 1927 2,251,055 Howard et al July 29, 1941 2,329,292 Perry Sept. 14, 1943 2,350,920 Perry June 6, 1944 2,393,176 Livar et a1. Jan. 15, 1946 2,457,377 Jensen Dec. 28, 1948 adapted to be supported by and