US3667892A

US3667892A - Control means for pressurized gas-fired space heater

Info

Publication number: US3667892A
Application number: US69043A
Authority: US
Inventors: Richard C Barnett; James D Boucher
Original assignee: General Electric Co
Current assignee: Trane US Inc
Priority date: 1970-09-02
Filing date: 1970-09-02
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06

Abstract

THIS INVENTION PROVIDES MEANS FOR CONTROLLING THE SUPPLY OF COMBUSTION AIR AND FUEL GAS TO GAS-FIRED SPACE HEATER MEANS EMPLOYING PRESSURIZED COMBUSTION MEANS INCLUDING A FUEL GAS-AIR MIXING AREA HAVING A VALVED SOURCE OF FUEL GAS AND A SOURCE OF PRESURIZED COMBUSTION AIR FLUID-CONNECTED TO IT. THE PRESENT INVENTION INTERPOSES MOVABLE DAMPER MEANS BETWEEN THE COMBUSTION AIR SOURCE AND THE GAS-AIR MIXING AREA AND SWITCH MEANS ACTUATABLE BY MOVEMENT OF THE DAMPER MEANS IN RESPONSE TO COMBUSTION AIR FLOWING BETWEEN THE COMBUSTION AIR SOURCE AND THE GAS-AIR MIXING AREA TO CONTROL THE OPENING AND CLOSING OF THE FUEL GAS SOURCE VALVE SUCH THAT FUEL GAS IS NOT ADMITTED TO THE GAS-AIR MIXING AREA UNLESS THE FLOW OF COMBUSTION AIR IS SUFFICIENT TO MOVE THE DAMPER MEANS TO ACTUATE THE SWITCH MEANS TO OPEN THE FUEL GAS SOURCE VALVE.

Description

June 6, 1972 R. c. BARNETT ETAL 3,667,892

CONTROL MEANS FOR PRESSURIZED GAS-FIRED SPACE HEATER 2 Sheets-Sheet 1 Filed Sept. 2, 1970 F'IGI INVE/JTZEE RC HARD C BARNET T 8 JAMES D. BOUCHER. BY

THEUQ. ATTORNEY PIC-5.2

June 6, 1972 c, BARNETT ETAL 3,667,892

CONTROL MEANS FOR PRESSURIZE'D GAS-FIRED SPACE HEATER Filed Sept. 3, 1970 2 Sheets-Sheet 2 F G INVENTORS RICHARD C. BARNE T & J'AMES D. BOUCHER THER ATTORNEY UnitedStates Patent 3,667,892 CONTROL MEANS FOR PRESSURIZED GAS-FIRED SPACE HEATER Richard C. Barnett and James D. Boucher, Tyler, Tex,, assignors to General Electric Company Filed Sept. 2, 1970, Ser. No. 69,043 Int. Cl. F23n 5/00 U.S. Cl. 431-31 3 Claims ABSTRACT OF THE DISCLOSURE This invention provides means for controlling the supply of combustion air and fuel gas to gas-fired space heater means employing pressurized combustor means including a fuel gas-air mixing area having a valved source of fuel gas and a source of pressurized combustion air fluid-connected to it. The present invention interposes movable damper means between the combustion air source and the gas-air mixing area and switch means actuatable by movement of the damper means in response to combustion air flowing between the combustion air source and the gas-air mixing area to control the opening and closing of the fuel gas source valve such that fuel gas is not admitted to the gas-air mixing area unless the flow of combustion air is suflicient to move the damper means to actuate the switch means to open the fuel gas source valve.

CROSS-REFERENCE TO RELATED APPLICATIONS The present invention is directed toward control means that are particularly adapted for use in pressurized gasfired space heater means, such as those described in detail in copending, commonly-assigned US. patent applications Ser. No. 47,433, filed June 18, 1970, by Roy W. Abbott and Ser. No. 66,800, filed Aug. 25, 1970, by James D. Boucher.

BACKGROUND OF THE INVENTION This invention relates to means for supplying heat to a space, such as a room, house, building or the like and, more particularly, to means for controlling the supply of combustion air and fuel gas to gas-fired space heater means which employ pressurized combustor means including a fuel gas-air mixing area having a valved source of fuel gas and a source of pressurized combustion air fluid-connected to it.

Heretofore, conventional gas-fired space heater or furnace means have most frequently employed rather crude cast iron or steel heat exchanger means having the general shape of a hollow box or clam shell to transfer heat generated by the combustion of a combustible gas-air mixture to an air stream circulated between the heat exchanger means and the space to be heated. And, these conventional heat exchanger means have usually been combined with similarly unsophisticated combustor or burner means which have been very much like those used in gas cooking ranges and wherein the combustion air that is mixed with the fuel gas is supplied to the combustor means at atmospheric conditions. In these conventional space heater means, the atmospheric combustor means is located beneath the heater exchanger and the combustion products rise upwardly by natural convection through the heat exchanger and are discharged to the atmosphere via an exhaust vent or flue that is connected to the top of the heat exchanger.

The aforenoted co-pending, commonly-assigned patent applications described gas-fired space heater means which are superior to the aforedescribed conventional heater means in that they permit considerable weight and Patented June 6, 1972 volume reduction in heat exchanger means material by employing a combination of highly efficient heat exchanger means for transferring heat generated by the combustion of a combustible gas-air mixture to an air stream circulated between the heat exchanger means and the space to be heated, and pressurized high intensity combustor means for mixing fuel gas with pressurized combustion air to produce and burn the combustible gas-air mixture. The pressurized combustor means include a fuel gas-air area having a valved source of fuel gas and a source of pressurized combustion air, such as an electrically motorized blower or the like, fluid connected to it. And, in operating such pressurized combustor means, it is desirable both that there be a flow of the pressurized combustion air from its source to the fuel gas-air mixing area before any fuel gas is admitted to that area and also that this fiow of combustion air be sufiicient to provide an optimum mixing ratio between it and the fuel gas in the fuel gas-air mixing area.

SUMMARY OF THE INVENTION The present invention provides control means for controlling the supply of combustion air and fuel gas to gas-fired space heater means employing pressurized combustor means including a fuel gas-air mixing area having a valved source of fuel gas and a source of pressurized combination air fluid-connected to it, which can assure that there will be a flow of pressurized combustion air from its source to the fuel gas-air mixing area before any fuel gas will be admitted to that area.

Basically, the control means of the present invention comprises movable damper means interposed between the combustion air source and the fuel gas-air mixing area, and switch means actuatable by movement of the damper means to control opening and closing of the fuel gas source valve such that fuel gas is not admitted to the fuel gas-air mixing area unless the flow of combustion air between the combustion air source and the fuel gas-air mixing area is sufiicient to move the damper means to actuate the switch means to open the fuel gas source valve. Preferably, the switch means includes a switch actuator that can be readily adjustably positioned with respect to the movable damper means in order to correct for variations in the combustion air source, eg variances in area line voltages available to power the electric motor of the combustion air source blower, etc., and to optimize the mixing ration between the combustion air and the fuel gas in the fuel gas-air mixing area.

BRIEF DESCRIPTION OF THE DRAWING The present invention is illustrated in the accompany ing drawing, wherein:

FIG. 1 is a somewhat schematic, partly sectioned, front elevational view of a space air-conditioning unit utilizing gas-fired space heater means incorporating a presently preferred form of the control means of the present invention;

FIG. 2 is an enlarged fragmentary sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a greatly enlarged fragmentary sectional view taken along line 33 of FIG. 1;

FIG. 4 is a fragmentary sectional view taken along line 44 of FIG. 3;

FIG. 5 is a fragmentary sectional view taken along line 5-5 of FIG. 4; and

FIG. 6 is a schematic wiring diagram showing the electrical circuitry for the control means of the present invention.

3 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing and, more particularly, to FIG. 1 thereof, there is illustrated somewhat schematically, an air-conditioning unit utilizing gas-fired space heater means 11 incorporating a presently preferred form of control means 12 provided in accordance with the present invention. The air-conditioning unit 10 is fluidconnected by right and left hollow conduit means 13 and 14 to a space 15 (shown in block), such as a room, house, building or the like, so as to condition air contained Within the space 15, as by supplying heat to or removing heat from an air stream, indicated by arrows 16, that is circulated between the space 15 and the air-conditioning unit 10 through the conduit means 13 and 14 by space air blower means 17. As shown, the air-conditioning unit 10 employs a gas-fired space heater means 11 to supply heat to the air stream, in combination with cooling means, including an evaporator section 18, to remove heat from the air stream 16. x

As illustrated in FIG. 1, the air-conditioning unit 10 includes a generally rectangular hollow box-like cabinet 19 that is subdivided by a vertically arranged partition 20 into a left compartment 21 and a right compartment 22. The cabinet left compartment 21 has an air inlet opening 23 in its upper wall that is fluid-connected to the space 15 by the left conduit means 14, while the upper wall of the cabinet right compartment 22 has an air Outlet opening 24 that is fluid-connected to the space 15 by the right conduit means 13. The cabinet left compartment 21 houses a cooling means evaporator section 18 and the space air blower means 17, while the cabinet right compartment 22 houses the highly efiicient heat exchanger means 25 and high intensity pressurized combustor means 26 that are combined to provide the gas-fired space heater means 11.

The gas-fired space heater means 11 is generally similar to that described in detail in the aforenoted Boucher patent application, except that the combustor means 26 is provided with the control means 12, which will be described in detail hereinafter.

As shown in FIGS. 1 and 2, the combustor means 26 includes an inverted, generally horizontally arranged, elongated trough 27 having generally vertically-arranged, downwardly extending

sidewalls

28 and 29 that are provided with a plurality of apertures along their upper and lower edges to respectively define primary combustion air inlet apertures 30 and secondary combustion air inlet apertures 31. The upper surfaces of the inverted trough 27 are surrounded by a combustion air supply plenum 32 that is fluid-connected to a source of pressurized combustion air, such as a combustion air supply blower 33. The combustion air supply blower 33 includes an impeller 34 that is rotated by an electric motor 35 and is housed in the upper right hand corner of the cabinet right compartment 22 with its inlet connected to a combustion air intake conduit 36 which extends outwardly from the cabinet 19 through an an opening 37 provided in the right side wall thereof. And, in accordance with a particular aspect of the present invention, the combustion air supply blower 33 has its outlet fluid-connected to the combustion air supply plenum 32 via a combustion air blower discharge conduit 38 and a hollow box-like control chamber 120 of the control means 12, which will be described in greater detail hereinafter.

As further illustrated in FIGS. 1 and 2, a generally horizontally disposed gas supply conduit 39 extends longitudinally through the inverted trough 27 and is provided with plural gas inlet apertures 40 that are located above the primary combustion air inlet apertures 30. The inlet of the gas supply conduit 39 is connected via a conduit 39a and a normally-closed electric control valve 41 of a well-known type with a source (not shown) of pressurized fuel gas, such as natural gas, propane or the like that is delivered to the valve 41 by a fuel gas source conduit- 42. The fuel gas inlet apertures 40 are arranged such that the fuel gas enters the inverted trough 27 generally parallel to the

trough side walls

28 and 29 and is turbulently mixed in a fuel gas-air mixing area 43 that is defined by the lower surface of the gas supply conduit 39 and the downwardly extending

trough side walls

28 and 29.

The rich combustible fuel gas-air mixture, which results from the turbulent mixing of pressurized fuel gas that is discharged from the gas inlet apertures 40 with the pressurized combustion air that enters the fuel gasair mixing area 43 via the trough primary combustion air inlet apertures 30 moves downwardly through the mixing area 43 and is ignited by a high voltage spark produced in a Well-known manner by igniter means such as an electric spark plug 44 that is generally horizontally arranged at the left end of the mixing area 43 at a point vertically spaced between the primary combustion air inlet apertures 30 and the secondary combustion air inlet apertures 31. This ignited mixture of fuel gas and primary combustion air is then further tnrbulently mixed with the pressurized combustion air which enters the fuel gas air mixing area 43 through the generally horizontal secondary combustion air inlet apertures 31 provided along the lower edges of the downwardly extending side walls 28 and 29' of the inverted trough 27 and produces a generally downwardly extending, extremely high intensity heat source or flame 45.

The highly intense heat from this flame 45 is now discharged from the lower or outlet end of the inverted trough 27 to an inlet at the upper end of the heat exchanger means 25 through a hollow box-like interconnecting conduit means 46. The intensity of the heat source or flame 45 that is produced by the high intensity pressurized combustor means 26 is generally similar to that produced by the combustor means described in the aforenoted Abott patent application, and is typically at least 300,000 B.t.u. per hour per cubic foot of the interconnecting conduit means 46, an intensity level far exceeding any previously achieved with the prior-art atmospheric combustor or burner means which have heretofore been commonly employed in conventional gas-fired space heaters.

The highly eflicient heat exchanger means 25 comprises a plurality of generally vertically arranged hollow tubes 47. The tubes 47 have their upper ends fluid-connected in parallel to the lower end of the interconnecting conduit means 46 provided between the bottom of the inverted trough 27 and the top of the heat exchanger means 25, while their lower ends are fluid-connected in parallel to an exhaust plenum 48 which directs the waste products of combustion to an atmospheric exhaust vent means including an elbow-shaped vent pipe 49 having an inlet leg 49a and an outlet leg 49b. The vent pipe inlet leg 49a is connected to the exhaust plenum 48 at the "bottom of the heat exchanger means 25 and extends outwardly from the airconditioning unit cabinet 19 through an opening 50 provided at the lower end of the cabinet right side wall, while the vent pipe outlet leg 49b extends upwardly outside the cabinet. The vent pipe inlet leg 49a is sloped downwardly towards its intersection or elbow 49c with its upwardly extending outlet leg, and liquid drain means 49a is provided at its lowermost point, as at the bottom of the vent pipe elbow 49c.

Preferably, as in the case of the heat exchanger means described in the aforenoted Abbott patent application, the outer surfaces of the hollow tubes 47 of the heat exchanger means 25 are provided with fin means 51 of the so-called spine-fin type that are generally similar to those described in detail in the commonly-assigned prior art US. Pat. No. 2,983,300, except that the tubes and the fins for the heat exchanger are preferably formed of a ferrous material, such as steel, rather than of a non-ferrous material, such as aluminum or copper as in the air cooling exchanger described in US. Pat. No. 2,983,300.

As shown in FIG. 1, the space air blower 17 has its inlet 52 aligned with the air inlet opening 23 for the cabinet left compartment 21 and has its discharge 53 fluid connected to the right cabinet compartment 22 via an opening 54 that is provided inthe partition 20, and is arranged such that rotation of its impeller 55 by its electric motor 56 will cause the air stream 16 to be circulated between the space 15 and the finned exteriors of the heat exchanger tubes 47. Hence, during operation of the combustor means 26 of the gas-fired space heater means 11, the right conduit means 13 serve as means for directing heated air from the air-conditioning unit cabinet 19 to the space 15 or as the so-called warm air conduit means, the left conduit means 14 serve as means for returning air from the space 15 to the air conditioning unit cabinet 19 for the reception of heat, or as the so-called return air conduit means, and the space air blower 17 serves as a means for circulating air between the space 25 and the gas-fired heater means 11. Thus, during operation of the pressurized combustor means 26 of the gas-fired heater means 11, the combustion products resulting from the ignition and burning of the pressurized fuel gas and combustion air that are mixed in the fuel gas-air mixing area 43 produce the highly intense heat source or flame 45, and they and the heat generated thereby are forced downwardly under the pressure provided by the combustion air supply blower 33 through the interconnecting conduit means 46 and tubes 47 of the heat exchanger 25, with the heat therefrom being transferred by condition, convection, and radiation, first to the interiors of the tubes 47, then to the finned exteriors of the tubes 47, and finally to the space air stream 16 that is circulated across the finned exterior of the tubes 47 by the space air blower 17. And, the waste products of the combustion are forced from the lower ends of the heat exchanger tubes 47 and into the exhaust plenum 48 at the bottom of the heat exchanger 25, then outwardly and downwardly through the vent pipe inlet leg 49a and finally upwardly to the atmosphere via the vent pine outlet leg 49b by the pressurized air supplied by the combustion air source blower 33. The rate of transfer of heat to the airstream 16 that can be accomplished by the heat exchanger means 25 is similar to that of the heat exchanger means described in detail in the aforenoted Abbott patent application, and is typically at least 3,500 B.t.u. of heat per hour per pound of material that is used in the tubes and the fins, a rate far exceeding any previously achieved with a rather crude prior box-like or clam shell-shaped heat exchangers which have heretofore been commonly employed in conventional gas-fired space heaters.

The pressurized gas-fired space heater means 11 is superior to the aforedescribed conventional atmospheric gas-fired space heater means in that it permits consider able weight and volume reduction in heat exchanger means material by employing the combination of a highly eflicient heat exchanger means 25 for transferring the heat generated by the combustion of the combustible gasair mixture to the air stream circulated between the heat exchanger means and the space to be heated and the pres surized high intensity combustor means 26 for mixing the fuel gas with the pressurized combustion air to produce and burn the combustible gas air mixture.

As described above, the pressurized combustor means 26 includes a fuel gas-air mixing area 43. This fuel gasair mixing area 43 has a source of fuel gas fluid-connected to it via the electric control valve 41 and also has fluidconnected to it a source of pressurized combination air, the combustion air supply blower 33. And, in operating such pressurized combustor means, it is desirable that there be a flow of pressurized combustion air from its source to the fuel gas air mixing area before any fuel gas is admitted to that area and also that this -flow of combustion air be suflicient to provide an optimum mixing ratio between it and the fuel gas in the fuel gas-air mixing area.

The present invention is particularly concerned with providing the control means 12 for controlling the supply of combustion air and fuel gas to the fuel gas-air mixing area 43 of the pressurized combustor means 26. The control means 12 can assure both that there will be a flow of pressurized combustion air from its source blower 33 to the fuel gas air-mixing area 43 before any fuel gas is admitted to the mixing area 43 by the valve 41 and also that this flow of combustion air will be sufiicient to provide an optimum mixing ratio between it and the fuel gas in the mixing area 43.

Basically, the control means 12 of the present invention comprises movable damper means 12d interposed between the combustion air source 33 and the fuel gas air mixing area 43 of the pressurized combustor means 26, and electric switch means 12s actuatable by movement of the mov able damper means 12d in response to flow of combustion air from its source 33 to the mixing area 43- to control the opening and closing of the fuel gas source electric valve 41 such that the fuel gas will not be admitted to the fuel gas-air mixing area 43 unless the flow of combustion air from the combustion air source 33 to the fuel gas air-mixing area 43 is sufficient to move the damper means 12d to actuate the switch means 12s to open the fuel gas source valve 41.

As illustrated in FIG. 1, the hollow box-like control chamber of the control means 12 is mounted adjacent the upper right end of the combustor means 26 with its top wall generally horizontally aligned with the combustor means top wall. As shown in particular detail in FIGS. 3-6, the control chamber 120 has an inlet opening 60 through its rear wall that is fluid-connected to the outlet end of the combustion air blower discharge conduit 38 and has an outlet opening 61 through its left side that is fluid-connected to the combustion air supply plenum 32 of the combustor means 26, which, in turn, is fluid-connected to the fuel gas-air mixing area 43 via the primary and secondary combustion

air inlet apertures

30 and 31 provided in the

side walls

28 and 29 of the inverted trough 27. And, the damper means 12d comprises a damper member 63 that is mounted for pivotal movement within the control chamber 12c by hinge means 64 fastened to the chamber top wall adjacent its intersection with the chamber rear wall.

The hinge damper member 63 has a cross-sectional configuration that is generally similar to an inverted V shape and includes a longer first leg 63a which extends downwardly from the hinge means '64 and is biased (counterclockwise as seen in FIG. 5) towards closure of the control chamber inlet '60 by a counter-weight 630 that is fastened by welding or other suitable fastening means to the lower surface of its shorter second leg 63b which extends forwardly from the hinge means 64 and toward the control chamber outlet opening 61.

As further shown in detail in FIGS. 3-6, the electric switch means 12s for controlling the opening and closing of the fuel gas source electric control valve 41 comprises an electric switch 65 of a well-known type that is commonly referred to as a micro-switch. The switch 65 comprises a housing 65h made of an electrically insulative material which contains a pair of normally-open electric switch contacts including a fixed contact 66 and a movable contact 67 (FIG. 6). And, a switch actuator 68 is mounted on the switch housing 65h for pivotal movement between a first position in which the switch contacts 66 and 67 remain open (FIG. 5) and a second position in which the contacts 66 and '67 are closed (FIG. 6). The normallyopen contacts 66 and 67 are connected in electrical series with the solenoid 41s of the electric control valve 41 for the fuel gas source across a pair of electric control power lines L1 and L2 (FIG. 6) such that the solenoid 41s will remain de-energized and the fuel gas supply valve 41 will remain closed unless the switch actuator 68 is pivoted to its second position closing the normally open contacts 66 and 67 and electrically energizing the control valve solenoid 41s to open the normally-closed control valve 41.

In particular accordance with the present invention, the switch housing 6511 is fastened by rivets or the like to a switch bracket '69 which is provided with an elongate slot 70 that receives a screw 71 which is inserted into a threaded opening that is provided at the right side of the control chamber 12c adjacent its lower rear end. And, the lower wall of the control chamber 120 is pierced by an elongate aperture 72 which permits upward passage therethrough of the free end of the switch actuator 68. With this arrangement, the actuator 68 of the switch means 12s can be interposed between the downwardly extending longer leg 63:: of the damper member 63 and the control chamber outlet opening 61 such that the fuel gas source valve 41 will remain closed unless there is a suificient How of combustion air from the combination air source or supply blower 33 through the combustion air discharge conduit 38 and the control chamber inlet 60 and against the rear face of the downwardly extending damper member longer leg 63a to promote sufficient pivotal movement of the damper member 63 about is hinge means 64 (clockwise as seen in FIG. to cause the downwardly extending longer damper member leg 63a to engage the switch actuator 68 and pivotally move the switch actuator 68 (counterclockwise as seen in FIG. 5) to its second or closed position (FIG. 6) to close the normally-open contacts 66 and 67 of the switch 65 and to energize the control valve solenoid 41s to open the normally-closed gas source valve 41. Further opening of the damper member 63 is prohibited by the switch actuator 68 which will not move past its second or closed position.

As previously noted, the flow of combustion air that is discharged from the combustion air supply blower 33 will be dependent upon the rotational speed of its impeller 34 which, in turn, will vary in accordance with the line voltage available to power its motor 35. Thus, if the line voltage is lower than average the rotational speed of the combustion air blower motor 35 and its impeller 34 will be slower than normal and the how of combustion air through the discharge conduit 38 to the control chamber 120 will be lower than normal. Hence, it will be necessary that the damper member longer leg 63a be pivoted farther away from the control chamber inlet '60 (clockwise as seen in FIG. 5) to pass the necessary combustion air flow through the control chamber 120 and into the fuel gas-air mixing area 43 to produce optimum mixing with fuel gas that is admitted to the mixing area 43. And, if the line voltage is higher than average, the reverse situation will apply.

However, the control means 1 2 of the present invention permit the switch actuator 68 to be adjustably positioned with respect to the damper means 12d by merely loosening the holding screw 71, slidably repositioning the slotted switch bracket 69 (and consequently the switch actuator 68) with respect to the loosened holding screw 71 and the damper member longer leg 63a, and resecuring the holding screw. As shown in FIG. 3, the control chamber 12c is provided with a pressure tap 73 for fluid-connecting a portable water manometer (not shown) to measure static fluid pressure within the control chamber 12c. With this arrangement, the combustion air supply blower 33 is started and the slotted switch bracket 69 adjustably positioned with respect to its holding screw 71 and the damper means 12d such that the switch actuator 68 is engaged and pivoted to its closed position (FIG. 6) only just when a particular desired pressure reading is obtained on the manometer. This desired pressure reading is, of course, indicative that the flow of the com.- bustion air (flow from its source 33 to the mixing area 43, is such that there will be optimum mixing in the area 43 between the combustion air and the fuel gas. Once the desired pressure reading is registered on the manometer, the holding screw 71 is then tightened to .iix the position of the switch actuator 68 with respect to the damper means 12d. .If the available line voltage for the combustion air blower motor 35 is below average, the switch bracket 69 and the actuator 68 must be moved away from the damper means 12d (to the left as seen in FIG. 5) to achieve the optimum rate of combustion air flow. On the other hand, if the available line voltage for the combustion air blower motor 35 is above average, the switch bracket 69 and actuator 68 must be moved toward the damper means 12d (to the right as seen in 'FIG. 5) to achieve optimum combustion air flow rate.

It should be apparent to those skilled in the art that while there has been described what, at present, is considered to be a presently preferred embodiment of this invention in accordance with the patent statutes, changes may be made to the disclosed apparatus without actually departing from the true spirit and scope of this invention. It is therefore, intended that the appended claims shall cover such modifications and applications that may not depart from the true spirit and scope of the present invention.

What is claimed is:

1. In a gas-fired space heater employing pressurized combustor means including a fuel gas-air mixing area having a source of fuel gas controlled by a valve and a source of pressurized combustion air fluid-connected to it, control means, comprising:

(a) movable damper means interposed between the combustion air source and the fuel gas-air mixing area; and

(b) switch means actuatable by movement of said damper means to control opening and closing of the valve such that the fuel gas is not admitted to the fuel gas-air mixing area unless the flow of combustion air between the combustion air source and the fuel gas-air mixing area is sulficient to move said damper means to actuate said switch means to open the fuel gas source valve;

said switch means including a switch actuator that is adjustably positionable with respect to said movable damper means.

2. The invention of claim 1, wherein said damper means is mounted for pivotal movement.

3. The invention of claim 2., wherein said switch actuator is mounted for pivotal movement.

References Cited UNITED STATES PATENTS 2,704,571 3/ 1955 Reichelderfer 43 13 1 2,787,318 4/ 1957 Wolfersperger 43 l-35l 2,790,042 4/ 1957 Porwancher 200-8 1.9 3,415,309 12/1968 Fiedler et a1. 43 l31 2,329,292 9/ 1943 Perry 431- X 2,586,411 2/ 1952 Wilson 431-90 X 2,806,102 9/ 1957 Giletto ZOO-81.9

CARROLL B. DORITY, 1a., Primary Examiner US. Cl. X.R. 43 190