US2266238A

US2266238A - Air conditioning system

Info

Publication number: US2266238A
Application number: US189082A
Authority: US
Inventors: Alwin B Newton
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1938-02-07
Filing date: 1938-02-07
Publication date: 1941-12-16
Anticipated expiration: 1958-12-16

Description

Dw 1941- A. B. NEWTON 2,266,238]

AIR CONDITIONING SYSTEM Fild Feb. '7, 1958 2 Sheets-Sheet z T HIGH Ll M IT' CO NTROLS 23 INVENTOR lwin B. Newlbn ATTORNEY- Patented Dec. 16, 1941 UNITED STATES PATENT OFFICE AIR CONDITIONING SYSTEM Alwin B. Newton, Minnea Minneapolis-Honeyw polis, Minn., assignor to ell Regulator Company,

Minneapolis, Minn., a corporation of Delaware Application February 7,1938, Serial No. 189,082

23 Claims.

This invention relates in general to air conditioning systems and is more particularly concerned with air conditioning systems of the type which are adapted to cool a space during the summer and to heat a space during the winter.

The primary object of my invention lies in the provision of a novel year-around air conditioning system which is adapted to automatically maintain the proper temperature and humidity withuin a conditioned space at all times. More specifivision of a system of this tyge with a heat engine iwpe of prime mover such as an internal combustion engine, and the provision of means for automatically cooling the engine and condenser when the system is operating on the summer cycle, and for transferring heat from the engine and condenser to the space when heat is necessary for maintaining proper conditions within the space.

Another object isin the provision of a system of this type with an easily controlled and efiicient arrangement for transferring heat from the exhaust gases of the internal combustion engine to the space and/orfor transferring waste heat from the engine to a supply of domestic water for heating the same.

In systems of this general type wherein heat is pumped from outside'into the space by means of a, reversed refrigeration system, the capacity of the system tends to decrease as the outdoor temperature falls. Heretofore, this has limited the application of installations of this character to locations in mild climates. It is a further object of my invention to provide a system of this type which may be utilized in severe climates as well as in mild climates, thereby enabling the advantages and economy of reversed cycle systems to be had in severe climates where economy in heating is mportant factor. In accoid ance with my invention, this result is achieved by the use of an additional heating device which is driven by the internal combustion engine which 7 drives the refrigeration compressor, and which remains out of operation as long as the reversed cycle system remains efiective, but which replaces the reversed cycle system for supplying heat and for loading the engine when. the reversed cycle system becomes ineffective.

Another factor which has limited the commercial development of reversed cycle systems 1 and 2.

is the initial cost of systems of this character. Due to systems of this type requiring considerably more apparatus than other types of systems such as steam, hot water, or hot air systems, reversed cycle systems have not been commercially feasible. It is an object of my invention to provide an arrangement for considerably lowering the initial costs of systems of the reversed cycle type. This object is achieved by the provision of an auxiliary heating device for supplying additional heat to the system, and a control mechanism for placing this auxiliary heater in operation during peak load conditions. By this arrangement, the installation may be made considerably smaller than would be necessary for carrying peak loads which occur during only a very small part of the heating season.

A further object of this invention is the provision of a simple and effective automatic control system for systems of the type mentioned, which provides for maintaining proper temperature and humidity conditions within the conditioned space. i

Other objects of my invention lie in various sub-combinations forming part of the complete system, and will become apparent from the following description and the appende'dclaims.

- For a full disclosure of my invention, reference is made to the following detailed description and to the accompanying drawings in which:

Figure 1 shows diagrammatically one form which my invention may take;

- Figure 2 illustrates diagrammatically a rmodisystem shown in Figure 1'; and

fication of the in which Figure 3 shows a modified form of exhaust gas I heat utilizing means which maybe employed in-v Q dependently or with the systems shown in Figures Referring to Figure 1, reference character] indicates a conditioning chamber having a fresh air inlet 2 and a return air inlet 3 which conducts air from a space being conditioned to the chamber l. The discharge end of the conditioning chamber I is connected to the inlet of a fan 4, which in'turn isconnected to a discharge duct 5 for conveying conditioned air to the space being conditioned; Within the chamber I is located a direct expansion cooling coil 6, a condenser heating coil 1, a jacket water heating coil 8, and an exhaust heating coil 9. Also located within the conditioning chamber I is a humidifier III which may take the form of a water pan having a heating coil located therein. The humidifier ll may be provided with a water supply pipe I2 and a float valve I3 for maintaining a predetermined water level within the water pan. Also located within the conditioning chamber I is an electric strip heater I4.

The direct expansion cooling coil Ii forms a part of a refrigeration system including a compressor l5. The discharge line l6 of the compressor leads to a condenser II for condensing the compressed refrigerant discharged by the compressor. The condensed refrigerant passes from the condenser I'I into a receiver I8 and from this receiver passes through a liquid line I9 which leads to a pair of solenoid or electrically controlled valves and 2|. The outlet of valve 2| is connected by means of a pipe 22 to an expansion valve 23 which'is located at the inlet of the evaporator coil 6. This expansion valve may be of any desired type having a bulb 24 connected Y to the evaporator outlet pipe 25. The pipe 25 is in turn connected to a pipe 26 which leads to the compressor inlet. The valves 20 and 2| are arranged to be alternately opened or closed by means of a control device which will be described hereinafter. Hence when the valve 2| is opened, the valve 20 will be closed. Under these conditions, it will be apparent that liquid refrigerant will flow from the receiver I8 through the expansion valve 23 into the cooling coil 6, thereby causing chilling of this coil and evaporation of refrigerant within the coil, the evaporated refrigerant passing back to the com- When the valve 20 is opened and the valve 2| is closed, however, liquid refrigerant will flow through valve 20 and pipe 21 to an expansion valve 28 which is located at the inlet of an outside evaporator coil 29 and will flow from this coil through a pipe 30 to the compressor inlet pipe 25 and hence back to the compressor. This action will cause heat energy to be absorbed by evaporation of the refrigerant within the evaporator 29, this heat then being supplied to the condenser II from which it will be transmitted to the heating coil I in a manner which will be described hereinafter.- The outside evaporator, it will be understood, may be subjected to outside atmosphere, may be placed underground, or may takethe form of a heat exchanger through which well. water or other heat-- ing medium is passed. From the description thus far it will'be apparent that the compressor I5, condenser I1, and evaporators 6 and 29 constitute a reversible cycle refrigeration system which is adapted to cool the air whenever the valve 2| is opened and which is adapted to heat the air whenever the valve 20 is opened.

During the heating cycle of the system; it is necessary to transfer heat from the condenser II to the heating coil I which is located within 'the conditioning chamber.

For this purpose a circulating pump 3| is provided. This pump may be driven by an electric motor 32 or if desired may be driven by the same prime mover which drives the compressor I5. The pump 3| is connected to a discharge pipe 33 leading to a check valve 34, which in turn is connected by a con uit 35 leading to the condenser |I.- The coolin medium outlet of the condenser |I is connected by a pipe 38 to a heat exchanger 31, the cooling medium passing through this heat exchanger into a conduit-38 which is connected by a pipe 39 to the inlet of the pump 3|. By this arrangement, it will be apparent that cooling medium is circulated by the pump 3| through the condenser and the heat exchanger 31 for thereby transferring heat from the condenser to the heat exchanger 31.

The heat exchanger 31 is provided with a heating coil 48. One end of this heating coil is connected by a pipe 4| to the inlet of the coil I which is located within the chamber l. The outlet of the coil I is connected to an electrical control valve 42, the outlet of this valve being connected by a pipe 43 to'the inlet of the coil 40. Coils 40 and I are therefore connected together for forming a closed circulatory system. This system may be charged with a volatile fluid such as alcohol or ether. When the valve 42 is opened, this volatile fluid will be evaporated within the coil 40, thereby cooling the heat exchange medium being discharged from the condenser. The evaporated fluid will then pass through the pipe 4| to the heating coil I wherein it will condense, thereby giving up the heat absorbed from the condenser to the air passing over coil I. The"condensed fluid will then pass through the valve 42 and pipe '43 backto the coil 40 for re-evaporation. When the valve 42 is closed, however, condensed volatile fluid will be trapped above the valve 42 thereby filling or partially filling coil 1 with condensate and also preventing any condensate from entering the 'coil 40. This will in turn partially or completely place .the heat exchanger I out of operation, depending upon the length of time that valve 42 is closed. By this arrangement, the valve 42 handles only a small quantity of condensed fluid and hence this valve may be relatively small.

During the cooling cycle of this system, the valve 42 will be normally 010m and hence no heat will be transferred from the condenser to the heating coil I. At this time, the condenser will be cooled by the passage of water from an outside source, such as a cooling tower, through the condenser. This arrangement will now be described. Reference character 45 indicates an electrical control valve, the inlet of which may be connected to a suitable source of cooling medium, such for instance as a cooling tower or a water main. The outlet of this valve is connected by a pipe 46 to the pipe 35 which leads to the condenser II. While the valve 45 may be controlled in various manners in accordance with my invention, I prefer to control this valve by means of a pressure controller 41 which is responsive to the pressure of the compressed refrigerant. This pressure controller may consist of a bellows 43 which is connected by a tube to the high pressure refrigerantline I6. This bellows may actuate a pivoted mercury switch carrier which carries a mercury switch 43 which is connected in series with the valve 45. This controller may be so designed and adjusted as to maintain the mercury switch 43 open so long as the pressure of the compressed refrigerant is below the value prevailing when the heating coil I is in operation while causing closing of the mercury switch 43 and consequent opening of the water valve 45 whenever the refrigerant pressure exceeds this value. When the system is operating on the heating cycle, heat will be transferred from the condenser to the heating coil I in such quantities as to prevent the pressure of the compressed refrigerant from rising above the setting of the'pressure controller 49 and consequently the valve 45 will be closed for preventing the supply of outside cooling water to the condenser. However, when the system is operating on the cooling cycle, closure of the valve 42 will prevent heat from being transferred from the condenser to the heating coil 1. This will result in the temperature of the condenser cooling medium rising, which will be followed by a rise in pressure of the condensed refrigerant. This pressure will continue to rise until it reaches the setting of the pressure controller 41 and .causes this controller to close the mercury switch 49 for opening the water supply valve 45. Cooled water from an outside source will then flow through the

pipes

46 and 35 into the condenser for condensing the refrigerant. This condenser cooling water will then pass through the pipe 36 into the heat exchanger 31 and from the heat exchanger 31 to the pipe 38, and will flow from pipe 38 through a relief valve 50. The cooling medium discharged through the relief valve 50 will then be either returned to the cooling tower, if such is used, or will be wasted. It will be understood that the relief valve 50 will-be loaded sufficiently to prevent opening thereof unless the valve 45 is opened. Consequently, whenever the valve 45 is closed, the relief valve 50 will close for maintaining the condenser cooling circuit closed at such time.

Referring to the compressor I5, this compressor may be driven by means of an internal combustion engine This engine may be provided with the usual exhaust manifold 52, intake manifold 53, starting motor 54, and generator 55. This engine may also be provided with a throttle valve or other type of speed or out-put controller 56. The engine 5| may drive the compressor l5 by mean's of any suitable power transmission means, such means being illustrated herein as comprising a drive shaft 51, pulleys 58 and 59, and cooperating belts 60.

In accordance with my invention, provision is made for utilizing the waste heat of the engine for supplementing the effect of the reverse cycle refrigeration system in heating the space during the heating cycle of the system, and for providing reheat when necessary during the cooling cycle. In order to transfer heatjrom the cylinder walls of the engine to the air being conditioned, a jacket water heat exchanger 6| is provided. This jacket water heat exchanger 6| is connected to the outlet of the engine water jacket by means of a pipe 62 which may have interposed therein a thermostat 63 for preventing overcooling of the engine. The outlet of the exchanger 6| is connected to the pipe 38 which leads to the circulating pump 3|, and the discharge of the circulating pump 3| is connected to the engine water jacket by means of a pipe 64. By this arrangement, hot water is circulated from the engine water jacket through the heat exchanger 6| and is returned to the engine water jacket by means of. the circulating pump 3|. The circulating pump 3|, therefore, acts to cause both a circulation of cooling water through the condenser l1 and the heat exchanger 40, and a circulation of cooling water between the engine water jacket and the heat exchanger 6|.

inlet of the coil 65, an electric control valve 69 being interposed in this conduit. The arrangement just described forms a closed heat transfer system, and this system may be charged with a volatile fluid. When the valve 69 is opened,v

liquid volatile fluid will be allowed to enter the coil 65. This will evaporate within the coil 65 thereby cooling the water being discharged from the engine into the heat exchanger 6|. The evaporated fluid then passes to the heating coil 8 wherein it condenses and gives up its heat to the air flowing across coil 8. The condensed or partially condensed volatile fluid will then pass from the coil 8 through pipe 61 into heating coil II in the humidifier pan, and will give up its re-,

this exchanger 10 being connected to an exhaust The heat exchanger 6| isprovided with-a coil 65.- The outlet of this coil 66 iscon'nected by a conduit 6.6 to the inlet of the jacket water heating coil 8 which is located ,within'the conditioning'chamber'l. The outlet of coil 8 is connected by" a conduit 6'| to the heating'coil l l located thehuniidifier pan'and' the outlet of this coil'i's connectedby'meansot a-oonduit 66 to the pipe H, which in turn is connected to the exhaust manifold of the engine. The exhaust gases from the engine pass over a coil 12 which is located within the heat exchanger 10. The coil 12 may be connected by a pipe 13 to the inlet of the exhaust heating coil 9 which is located within the conditioning chamber, and the outlet of the latter coil may be connected by pipe 14 'to the inlet of coil 12, thereby forming a closed heat transfer system. This system may also be charged with a volatile fluid for thereby transferring heat from the coil I2 to the coil 9. Similarly, to the other closed heat transfer systems described, this heat transfer system may be provided with a control valve 15 for preventing the transfer of heat from coil 12 to the heating coil 9.

If desired, the exhaust gases may be also utilized for heating domestic water. For this purpose a domestic hot-water tank 16 having a heating coil 11 may be ,utilized. In order to prevent overheating of the domestic water, a three-way valve 18 may be interposed between the exhaust pipe 19 and the heating coil 11, this valve also being connected to a by-pass -for by-passing exhaust gases around the coil TI. The valve 18 may be controlled by means of a thermostat 8| which is responsive to the temperature of the domestic hot water.

stat 8| may include a bellows '82 which is connected by a capillary tube 83 to a control bulb 84 located within the tank I6. This bellows cooperates with a pivoted mercury switch carrier' position the mercury switch 65 for causing'the valve 18 to pass all of the exhaust gases through the heating coil 11. When the domestic water- The thermo- I temperature becomes excessive, however, the bellows will expand, tilting the mercury switch 85 to the position shown for thereby causing the valve I8 to by-pass the exhaust gases around the heating coil 11-.

With a reversed cycle' heating system as described, it will be apparent that as the outdoor temperature becomes colder, less and less heat will be picked up by the outside evaporator. This will result in less evaporated refrigerant being returned from the outside evaporator 29 to the compressor which will, in turn, result in decreasing the load on the compressor. This action will, in turn, reduce the load applied upon the engine and consequently the waste heat given off by the engine will be lowered. Thus at the very time that more heat is necessary for heating the space, the system will tend to become unloaded thereby actually supplying a smaller quantity of heat than at times when the heating load is relatively light. In order to avoid this shortcoming of a reversed cycle heating system, I have provided for loading the engine 5| whenever the reverse cycle refrigeration system becomes ineffective for heating the space. This arrangement will now be described. Reference character 99 indicates an electric generator which is driven by the internal combustion engine through the medium of pulleys 9| and 92 over vwhich run belts 93. The pulley 92 is preferably provided with a suitable electrically controlled or magnetic clutching device which is controlled by

wires

94 and 95 for thereby selectively connecting the generator to the engine shaft, or for disconnecting the generator therefrom. The generator 99 may be connected by wires 96 and 91 to the strip heater I4 which is located within the conditioning'chamber. It will be apparent that whenever the clutch forming a part of pulley 92 is engaged, the generator 99 will be rotated by the engine, thereby loading the engine 5| and supplying energy to the strip heater I4. Thus, the additional load upon the engine is utilized for heating the space. Due to the throwing of this electric heater load upon the engine 5|, the

waste. heat given off by the engine will be increased and consequently more heat will be supplied to the air by the heaters 8 and 9. Hence, when the clutchis engaged the heat out-put of the system will be considerably increased thereby providing for heating the space despite the fact that the outside temperature may fall so low as to make the reversed cycle heating system 'inefiective.

In accordance with my invention, I also provide for supplying outside heat to the syst whenever the system becomes incapable of heating the space by the action of the internal combustion engine alone. For this purpose, a gas or other suitable type burner I99 may be located within the exhaust gas heat exchanger I9. This gas burner may be controlled by means of a motorized gas valve I9I, which in turn, is controlled by the control mechanism which will be hereinafter described. My invention also provides for automatically controlling the system just described in a manner to provide for mainto open the throttle valve 56 wider.

taining proper temperature and humidity oonwhich will now be described.

character I95 indicates generally a low limit thermostat which may be located within the space being conditioned or in thereturn duct 8. This thermostat may be of any desired This actionis obtained by the conby a potentiometer type of controller and assumes intermediate positions corresponding to the position of the potentiometer slider upon the potentiometer coil. In the present instance, the

thermostat I95 is connected to the proportioning motor I I9 in a manner to cause clockwise rotation'of its operating shaft III as the slider I98 moves to the right across the resistance I99. Hence, upon a decrease in space temperature, the bellows I99 of the thermostat I95 will contract, thereby causing movement of the slider I98 to the right across the resistance I99 which will be followed up by a clockwise movement of the motor shaft III. The thermostat I95 may be so designed as to cause engagement of the slider I98 with the extreme left-hand end of resistance I99 when the space temperature rises to 74 F., and to engage the extreme right-hand end of said resistance when the space temperature falls to F. Hence, by this arrangement the motor shaft III will assume an extreme counter-clockwise position when the space temperature is at or above 74 R, will gradually shift clockwise upon fall in temperature, and will reach its extreme clockwise limit of rotation when the space temperature falls as low as 79 F.

The various control valves 29, 2|, 42, 69, I5, and IM are preferably of the type which remain closed when deenergized and' which open when energized. These valves and the magnetic clutch of generator pulley 92 are controlled by means of a series of mercury switches H5, H6, H1, H8, H9 and I29 which are actuated sequentially by means of a series of cams |2|, I22, I23, I24,

I25, and I26 which are'mounted upon the motor shaft I I I. These cams are arranged on the shaft III in a manner to cause sequential closing of the mercury switches in the order named as the shaft III rotates in a clockwise direction and to cause these switches to be tilted toopen position ranged to control a proportioning motor I8! which is arranged for actuating the throttle valve 56. As will be more completely described later, the movement of the slider I2'I in a clockwise direction across the resistance I28 will have the effect of causing the proportioning motor I'8I Therefore, this arrangement will provide for increasing'the engine speed upon a decrease in space temperature.

Preferably, the engine 5| is provided with an arrangement for causing automatic starting of the engine whenever the throttle valve is opened and for stopping the engine whenever the throttle valve 58 is moved to closed position by its controller. For this purpose the proportioning motor I8| may be provided with an auxiliary 1 switch I82 which is illustrated herein as helm:

of the mercury type which is actuated by means changes in temperature.

temperature, the bellows I52 will expand thereby of the actuating lever I33 of the proportioning motor. This switch is so mounted upon the lever I33 as to be tilted to closed position whenever the throttle valve 56 is opened slightly, and is arranged to be tilted to open position whenever the throttle valve 56 is closed beyond this-point. The mercury switch I32 is arranged to control an automatic starting circuit for the engine which will now be described. Reference character I34 indicates a storage battery, one terminal of which may be grounded as shown. The other terminal of the storage battery I34 is connected to the switch I 32 by means of wire I35, and the switch I32 is also connected to the control terminal of a starting relay I36 by means of wire I31. This starting relay may'be of the type shown in Patent No. 1,773,913 issued to L. K. Loehr et a]. on August 26, 1930. This type of starting relay is arranged to energize the starting motor whenever the control circuit for the relay is energized, and for this purpose the starting relay I36 is connected to the starting motor 54 and to the storage battery I34 by means of wires I38 and I39; The wire I31 which leads from the mercury switch I32 to the control terminal of the starting relay is also connected to the engine ignition coil I40. Hence, when the mercury switch I32 is closed by opening movement of the throttle valve 56, the ignition circuit for the engine will be completed, and also the starting relay willbe energized for complet-.

ing a circuit from the battery through the starting motor, thereby cranking the engine. This starting relay is also arranged to deenergize the starting motor automaticallywhen the engine starts, as indicated by the starting motor taking less current. This relay is also arranged in a manner to prevent energization of the starting motor so long as the engine is in operation, as indicated by operation of the generator. For this purpose the starting relay is connected to the generator 55 by means of a wire I. The generator 55 is also connected to the battery I34 through a reverse current relay I42 in the usual manner. By the arrangement just described, whenever the throttle valve 56 is opened, the ignition circuit for the engine will be completed and the starting motor will be caused to operate until the engine is started, at which time it will be automatically deenergized. The engine I will then continue to operate until the throttle valve 56 is closed thereby opening the mercury switch I 32 and breaking the ignition circuit.

The throttle valve motor I3I is also arranged to be controlled by means of a high limit space thermostat I50 and a high limit humidity controller I5I. Referring to the thermostat I50, this thermostat may be located either within the conditioned space or within the return duct 3.

This controller may be of any desired type and is illustrated as comprising a bellows I52 cooperating with a bell-crank lever having an actuating arm I53 and a control arm or slider I54 which is arranged to engage a resistance I55 for forming a control potentiometer. The bellows I52 contains a suitable volatile fluidand-conse quently this bellows expands and contracts with Upon an increase in rotating arm I53 in a counter-clockwise direction against the action of spring I56, thus shift-.

ing the slider I 54' to the left across the resistance I55. Upon a decrease in temperature, the

' I59. The slider I59 in turn is adapted to engage a resistance I60 for forming a control potentiometer. Upon a decrease in relative humidity, the strands I51 willshrink thereby causing a counter-clockwise movement of the bell-crank lever against the action of a spring I6I, thus shifting the slider I59 to the right across resistance I60. As the relative humidity increases,

however, the strands will increase in length thereby permitting the spring I6I to shift slider I59 to the left. This instrument may be so designed and adjusted as to cause the slider I59 to engage the right-hand end of resistance I60 when the relative humidity falls below 40%, while engaging the left-hand end of said resistance when the humidity rises to 60%.

The proportioning'motor I3I is preferably of the type shown and described in the Taylor patent previously mentioned. Upon reference to this patent, it will be noted that this type of proportioning motor is provided with three control terminals and which are herein marked as R, B and W. The motor is adapted to assume positions corresponding to the relative values of the resistance connected between terminals R and B and between terminals R and W. For instance, if the resistance interposed between terminals R and B is exactly equal to the resistance interposed between terminals R and W, the motor will assume mid-position. If the terminals R and B should be substantially short-circuited, however, while resistan'c is interposed between terminals R and W, the otor will run to an extreme position at which the motor valve is wide open. On the other hand, should the terminals R and W be short-circu-ited while resistance is interposed between terminals R and B, the motor will run to its other extreme position at which the throttle valve is completely closed. For intermediate relationships between the resistance which is connected between terminals R and B and R and W, it will be understood that the motor I3I will assume intermediate positions corresponding to the relationship between the resistances.

The type of proportioning motor just described is, of course, adapted to be controlled by means of one or more potentiometer type of controllers, and in accordance with my invention, the throttling valve motor BI is controlled by the conjoint action of the high limit space thermostat I50, the high limit humidity controller I5I, and the potentiometer formed by slider I21 and resistance I28 which is actuated-by the low limit space thermostat I05 through the medium of the proportioning motor IIO. Referring to the connections between the motor I3I and the various control potentiometers, it will be noted that terminal R of the motor is connected by wire I65 to the slider I54 0! the high limit controller I50. The terminal B of the motor is connected by wires I66, I61, I68, and I69 to the left-hand tact segment I which is joined to the lower end of resistance I28. The terminal W of the motor is connected to the upper end of resistance I28 through the contact segment I29 by means of wire I10. The right-hand end of the resistance I55 is connected to the slider I59 by means of wire I1 I, and the right-hand end of resistance I60 is connected to the slider I21 by wire I12.

With the sliders I21, I54 and I59 in the posi tion shown, the space temperature is approximately 78.5 as indicated by the slider I54 engaging the center of resistance I55. For this value of temperature, the slider I21 is engaging the upper end of contact segment I29 due to the proportioning motor IIO having been rotated to its extreme counter-clockwise position. Also, the space relative humidity is below as indicated by the slider I59 of the humidity controller engaging the right-hand end of resistance I60. With the sliders I21 and I59 in the positions shown, the high limit thermostat I will be placed in full control of the motor I3I. It will be noted that the slider I54 of this controller is directly connected to terminal R of the motorand the left-hand end of resistance I55 is connected directly to terminal B of the motor by wires I66 and I61. The right-hand end of the resistance I55 at this time is connected to terminal W of the motor as follows: terminal W,

wire I10, segment I29, slider I21, wire I12, slider I59, and wire In to the right-hand end of resistance I55. It will now be apparent that the slider I54 of the thermostat I50 is dividing the resistance I55 into one portion which is connected across terminals R and B of the motor and into another portion which is connected across terminals R and W of the motor. Due to the resistances connected across the motor being equal, the motor has assumed mid-position in which the throttle valve 56 is half open as shown.

If the space temperature should increase, the slider I54 will be shifted to the left across re-. sistance I55 which will decrease the portion of this resistance which is connected across terminals R. and B and will increase the portion of the resistance which is connected across terminals R and W. In response to this change in relationship between the resistances connected across the motor terminals, the motor will rotate its operating lever I33 in a clockwise direction an amount corresponding to the movement of the slider I54 across the resistance I55. This will shift the throttle valve 56 to a further open pos tion and thus increase the speed of the engine. This, in turn, will cause more cooling to be done by the system for counteracting the rise in temperature. Conversely, should the space temperature fall, the slider I54 will be shifted to the right across resistance I55 thereby decreasing the resistance connected between terminals R and W and increasing the resistance connected between terminals R and B. This will cause movement of the motor I3I in the opposite direction for moving the throttle valve 56 to a further closed position, thus decreasing the engine speed i to counteract the drop in temperature. From the foregoing, it should be apparent that when the space temperature is above 15 F. and the humidity is at 40% or below, the high limit space thermostat I50 will be in full control of the engine speed and will graduatingly vary this engine speed in a manner tending to maintain the constant space temperature. Due to the wide range of the controller I50, however, this controller will increase the space temperature must rise, and

consequently as the load on the system increases, the space temperature must rise to such a value that the controller I50 causes operation of the engine 5I at a speed which prevents further rise.

in temperature. Consequently, as the outdoor temperature increases, the temperature maintained by the high limit space thermostat will be increased.

The control arrangement disclosed will also cause operation of the engine in the event that the relative humidity becomes excessive and this will occur even though the space temperature may be below the control point of the high limit controller I50. A condition of this type often exists during cool damp weather. At this time, the slider I54 of the controller I50 will engage the right-hand end of resistance I55. This will connect terminal R of the motor I3I to the slider I59 of the humidity controller as follows: terminal R, wire I65, slider I54, and wire I1I to slider I59. Terminal B of the motor I3I, it will be noted, is connected directly to the left-hand end of resistance I50 by wires I65 and I60. Terminal W of the motor at this time is connected to the right-hand end of resistance I60 as follows: terminal W, wire I10, segment I29,'slider I21, and wire I12 to resistance I60. Therefore, at this time the potentiometer of the humidity controller is operatively connected to the proportioning motor I3I for controlling the position assumed by this motor. With the slider I59 in the posi-. tion shown at which the relative humidity is low, terminals R and W of the'motor will be substantially short-circuited, while the entire resistance I60 will be connected between terminals R and B. This would cause the motor I3I to completely close the throttle valve 56 thereby preventing operation of the engine. If, however, the relative humidity increases, the slider I59 will travel to the left across resistance I60 which will place a portion of the resistance I60 between terminals R and W and will decrease the portion of the resistance which is connected between terminals R and B. This will cause the motor I3I to open the throttle valve an amount corresponding to the movement of the slider I59 across res'istance I60. Therefore, the humidity controller I5I is capable of causing opening of the throttle valve and operation of the engine whenever the relative humidity becomes excessive. The high limit thermostat I50 and the humidity controller I5I, therefore, cooperate in controlling the throttle valve position, and the position assumed by the throttle valve is determined by the conjoint action of these two controllers, the throttle valve being opened further upon an increase in either temperature or humidity and being moved towards closed position upon a decrease in values of these conditions.

I During the heating cycle of the system, therela'.ive humidity will usually be below 4%, and hence the slider I59 will engage the right-hand end of resistance I60, as shown. Also at this.

time, the space temperature will be below F. and consequently the slider I54 of thermostat I50 will engage the right-hand end of resistance I55. This action will connect the slider I21 of the winter control potentiometer to terminal R of the motor as follows: terminal R, wire I65, slider I54, wire I1I, slider I50, and wire I12 to slider I21. Terminal Wof the motor it will be noted, is connected to the contact segment I20 by means of wire I10, and terminal B of the motor is connected to the contact segment I30 by wires I66, I68, and I69. This, therefore,placesthe potentiometer formed of slider I21 and resistance I28 in operative control of the proportioning motor I3I. At this time, it will be noted that resistances I55 and I60 are connected in parallel between terminals R and B of motor I3I. Thus resistance I55 is connected across terminals B and R as follows: terminal R, wire I65, slider I54, resistance I55, wire I61, and wire I66 to terminal B. The resistance I60 will be connectedinparallel with resistance I55 by means of wire I1I, slider I50, and wire I68. These resistances being connected across terminals R and B would have the the engine speed when the space temperature begins falling below 72 F. and will modulate the engine speed in a manner tending to maintain the space temperature between limits of 72 F. and 70 F. The control arrangement just described, therefore, will cause operation of the engine whenever the space temperature rises to a value indicating that cooling is necessary or.

effect of crowding the operating range of the potentiometer formed of slider I21 and resistance I20 towards one end of resistance I28. In order to avoid this result and thereby obtain closer control, the effect of resistances I55 and I60 is balanced out by means of resistance I which is connected between terminals R and W.

' This resistance I15 is made equal in value to the combined parallel resistances I55 and I60 and consequently completely balances the effect of these resistances on the proportioning motor I3 I.

As pointed out previously, the s 'der I21 is rotated in a counter-clockwise directi n upon a decrease in space temperature. With the low limit controller I05 in the position shown, the space temperature is at or above 74 F., and consequently the motor shaft III is in its extreme counter-clockwise limit of rotation at which the slider I21 engages the upper end of segment I20. For this value of space temperature, the.

terminals R and W of the motor I3I will be substantially short-circuited while the resistance I28 will be connected across terminals R and B. This would cause the motor I3I to completely close the throttle valve 56 and place the engine 5I out of operation. As the space temperature begins falling, the motor shaft III will be rotated clockwise. However, until the space temperature falls to 72 F., the slider I21 will merely contact the contact segment I and no change in position of the throttle valve motor will take place. If the space temperature falls below 72 F., the slider I21 will begin contacting the resistance I28 and will place part of this resistance between terminals R and W and will decrease the portion of this resistance which is connected between terminals R and B. This will cause the motor I3I to open the throttle valve 56 an amount proportionate to the movement of slider I21 across the resistance I28. Consequently, as the space temperature falls below 72 F., the engine 5| will be placed into operation and its speed will be increased upon further decrease in temperature below this value. When the space temperature falls to 70 F., the slider I21 will engage the lower end of resistance I20 and come-'- quently will cause the throttle valve 56 to be wide open. Upon still further decrease in temperature, the slider I 21 will engage the contact segment I30. This will permit the throttle valve to continue to remain in wide open position. From the foregoing, it will be seen that the low limit space thermostat I05 will take control of falls to such a value as to indicate that heating is necessary. Also, the engine will be placed into operation whenever the space relative humidity becomes excessive. In addition, the engine speed will be modulated in accordance with the requirements for cooling, for heating, or for dehumidification.

Operation of Figure 1 With the parts in the position shown, the system is operating on the cooling cycle, as indicated by the slider I54 of the high-limit space thermostat engaging the center of resistance I 55. This in the manner just described has caused the motor I 3| to shift the throttle valve 56 to half are connected in circuit with the

valves

42, 69,

} open, the clutch is disengaged and consequently the generator 90 is not being driven at this time. The mercury switch I I8 at this time is tilted for causing bridging of the right-hand electrodes thereof which will cause energization of valve 2| as follows: line wire I16, right-hand electrodes of mercury switch II8, wire I11, valve 2I, and wire I18 to ground I19. Therefore, at this time the valve 2| will be opened thus placing the air stream or summer evaporator 6 into operation for cooling the air. Due to the valve 42 being closed, heat is not. absorbed from the condenser cooling water by the heat exchanger 31 and consequently the pressure of the compressed refrigerant has risen to a value which causes the pressure controller -41 to open the water supply valve 45, thereby supplying cooling water to the condenser and to the internal combustion engine 5I, thus providing for condensing the compressed refrigerant and for preventing the engine 5| from overheating. During this operation of the system on the cooling cycle, the engine speed will be increased upon increase in either temperature or relative humidity and will be decreased upon decrease in value of these conditions in a manner to maintain proper comfort conditions within the conditioned space, as previously described.

In the event that the relative humidity should be excessive while the space temperature is relatively low as occurs in cool damp weather, the relative humidity controller will cause operation of the engine 5.I for dehumidifying the air, even though no cooling is required. Due to the cooling humidifying action of the coil 6, the space temperature will begin falling. When the space temperature begins falling below 14 F., the low limit controller I will cause clockwiserotation of the shaft III. The first action of this rotation. will be to close the mercury switch II5. Closure of this switch will energize the valve 42 as follows: line wire I16, mercury switch II5, wire I80, valve 42, and wire I8I to ground. Energization of valve 42 will cause opening thereof which places the heat transfer system between heat exchanger 31 and the heating coil 1 in operation. This will provide heat for reheating the air after it has been cooled due to the action of cooling coil 6. The heater 1, it should be noted, is supplied with heat absorbed from the condenser and internal combustion engine. Due to the cooling efiect of heat exchanger 40 on the water circulated in the system, the cooling effect of the condenser will be increased which will cause the compressor discharge pressure to decrease, thereby causing closing of the water supply valve 45. This, therefore, provides for economy in cooling water supply for the condenser and internal combustion engine as it reduces the necessary additional cooling water to a minimum.

The described control arrangement for the reheater coil 1 will provide for floating control of the effective area of the reheatercoil 1 in accordance with the demand for reheat. Prior to the demand for reheat, it will be understood that the reheater coil 1 will be full of condensate due to the trapping of condensate therein by the closed valve 42. Upon demand for reheat, the valve 42 will be opened in the manner described, thus allowing condensate to trickle from the coil into the boiler or heat exchanger 40. Due to this withdrawal of condensate fromcoil 1,

vapor will take the place of the withdrawn con- I densate, thus causing a portion of the coil area to become heated. If the demand for reheat is light, the space temperature will, rise suflioiently to cause the valve 42 to be again closed before a large portion of the coil will be made efiective. The coil will then begin refilling with condensate which will eventually result in reopening of the valve 42 due to falling space temperature. It will be apparent that the heavier the demand for reheat becomes, the longer valve 42 will -remain open. Consequently, as the heat demand becomes heavier, the effective coil area will be increased. The control arrangement just described will therefore act to vary the effective reheater coil area in accordance with demand for reheat.

Under normal conditions, the reheater coil 1 will be suflicient for supplying the necessary reheat. If, however, an unusual condition should occur requiring an extraordinary amount of reheat, the space temperature will fall further, thus causing shaft III to be rotated clockwise thereby closing the mercury switch II6 which energizes valve 69 as follows: line wire I16, mercury switch II6, wire I82, valve 69, and wire I83 to ground. At this time, thevaive 42 will remain open thus placing the entire surface of coil I in operation. Also at this time the effective heating surface of the heating coil 8. will be varied in the same manner as described in connection with coil 1, for maintaining a constant temperature within the space.

lows: line wire I16, mercury switch II1, wire I84, valve 15, and wire I85 to ground. This will place the heating coil 9 in operation, and its efiective area will be varied in a manner to supply the necessary reheat as previously described. From the foregoing, it will be apparent that the heating coils are operated in sequence, and the effective area of each is controlled in a manner to provide a graduating control of reheat over a very wide range.

As the weather changes from a value requiring cooling or dehumidification to a value requiring heating, the space temperature will begin falling and also the space relative humidity will be below 40% and consequently the control arms of the sliders I54 and I59 of the controllers I and'I5I will engage the right-hand ends of their respective resistances, which in a manner previously described places control of the throttle valve motor with the potentiometer formed of slider I21 and resistance I28. As the space temperature continues to fall, the shaft I II will be rotated clockwise thereby sequentially closing the mercury switches H5, H6 and H1 which will open

valves

42, 69, and 15 for conditioning the heating coils I, 8, and 9 for operation, thereby providing for transferring the condenser heat, the jacket heat of the engine, and the exhaust heat of the engine to the air. Until the space temperature falls to 72 F., no heat for the space will be necessary. Until this occurs, the slider I 21 will continue to ride on segment I29, and hence the engine will not be placed into operation. Also the mercury switch II8 will remain in the position shown which causes energization of the valve 2I and deenergization of valve 20 which will permit the system to operate on the cooling cycle under control of the high limit humidity controller in the event that the humidity should become excessive. However, when the space temperature falls to 72 F., the mercury switch I I8 will be tilted to its other position thereby deenergizing the valve 2I for placing the air stream evapor tor out of operation. This will also cause en rgization of valve 20 as follows: line wire I16, left-hand electrodes of mercury switch II8, wire I86, valve 20, and wire In the event that heating coils 1 and 8 should III will rotate still further for closing mercury switch II1, which will energize valve 15 a fol- I81 to ground. This will result in opening of the valve 20 for placing the outside evaporator 29 into operation. Therefore, when the space temperature falls to 72 F., the action of the refrigeration system will be reversed from cooling to heating. As the space temperature falls below 72 F., the slider I21 will traverse the resistance I28 and thus increase the engine speed. As previously described, the engine speed will be increased and decreased in a manner to maintain the space temperature between 70 F. and 72 F.

As weather conditions become severe, the amount of heat which canbe picked up by the outside evaporator 29 will decrease. This will result in a smaller amount of evaporated refrigerant passing to the compressor, which would have the action of unloading the compressor. Due to thisunloading of the compressor, .the engine 5I will be unloaded and consequently will deliver a smaller amount of waste heat. Thus at this tim when the heating load is the greatest, the reversed cycle system tends to refuse to function thereby causing the heat supply to the space to begin falling off. This action will result in the space temperature continuing to fall. When the space temperature falls to a value, for instance, of 69 F., the cam I25 on shaft III will cause closure of mercury switch 9 which will energize the magnetic clutch in the generator drive as follows: line wire I16, mercury switch H9, wire 94, magnetic clutch, and wire to ground. This will cause engagement of the magnetic clutch and consequently will place the generator 90 into operation. Operation of generator 90 will cause heating of the strip heater It for thereby increasing the amount of heat supplied to the space. Also, due to the additional load impressed upon the engine 5|, the engine will supply an increased amount of waste heat to the space. Thus, whenever the outdoor temperature becomes so low as to render the reversed cycle heating system ineflective, the electric heater I4 is placed into operation, which has the effect of supplementing or replacing the action of the reversed cycle system. In the event that this should fail to maintain the space temperature, the shaft III of the proportioning motor 0 will rotate until the cam I26 causes closing of the mercury switch I20. This will cause opening of the valve |0| for supplying gas to the burner I00. This burner will be ignited by means of any suitable type of pilot, and consequently additional heat will be supplied to the system for thereby maintaining proper temperature conditions within the space.

The system just described, therefore, is entirely automatic in operation and serves to provide for heating, cooling, humidifying and dehumidiflcation of the space.

Figure 2 Referring to Figure 2, this figure shows a system of the same general type as shown in Figure 1. In this system, however, the intermediate heat exchangers 31, GI and have been omitted and the cooling water for the condenser and internal combustion engine is passed directly through the air stream heaters I and 8, respectively. Also in this system, the exhaust gases are passed. directly through the air stream heater 9'. The reversible cycle refrigeration system is exactly th same as illustrated in Figure 1 .and consequently this system is not redescribed at this point.

Reference character 200 indicates generally a circulating pump which corresponds to the pump 32 of Figure 1. This pump discharges through a check valve 201 into a supply pipe 202 which is connected by pipes 203 and 204 to the cooling water inlet of the condenser l1 and to the inlet of the engine water jacket, respectively. The cooling water outlet of the condenser is connected to a pipe ing coil '1, the outlet of which is connected to a valve 42'. The outlet of this valve, in turn, is connected to the inlet of the circulating pump 200 by means of a pipe 205. When the valve 42' is open, it will be apparent that circulating pump 200 will cause a circulation of cooling water from the outlet of the coil I through the condenser for condensing the refrigerant and back to the heating coil 'l'. The outlet of the engine water jacket is connected by a pipe 201 to the inlet of the heating coil 8' and the outlet of this heating coil is, in turn, connected to the coil II which is located within the humidifier II. The outlet of the coil H is, in turn, connected to a valve 69' and this valve is, in turn, connected by a pipe 208 to the pipe 205. By this arrangement, when the valve 85' is open, the circulating pump 200 will cause a circulation of cooling water 205 which leads to the air stream heatthrough the engine and heating coils 0' and H back to the circulating pump.

As in th case of Figure 1, the heating coils 1' and 0' are not normally in operation during the cooling cycle of the system, and hence it is necessary to provide for circulating water from an outside source through the condenser l1 and the engine water jacket in order to provide for condensing of the refrigerant and cooling of the engine when the system is operating on the summer cycle. To this end, a water supply pipe 2|0 is connected to the discharge of the circulating pump on the down stream side of the check valve 20|. Intel-posed in the water supply pipe 2|0 is a pressure actuated valve 2 which has a tube 2 I2 connected to the compressor discharge line Hi. This valve may be of the type which is biased to closed position and will remain closed until the pressure of the compressed refrigerant rises to a predetermined value. When the pressure rises to this value, the valve 2 II will begin opening and supply water through the pipes 202 and 203 to the condenser II for thereby increasing the condensing action for maintaining the compressor head pressure at this value. This water will be discharged from the condenser by means of pipe 205 to which is connected a relief valve 2|3 which permits the water to flow to waste or back to the source of cooling water. During the heating cycle of the system, water supply valve 2| I is closed, due to valve 42' being open. At this time the relief valve 2| 3 will remain closed thereby preventing escape of the cooling water from the system.

When the valve 2 opens to admit cooling water to the condenser, it will also admit cooling water to thewater jacket of the engine for cooling the engine, this water then flowing through relief valve 2 to waste or back to its source.

It will be understood that if desired an electrically actuated type of valve such as 45 of Figure 1 may be utilized in place of valve 2 of Figure 2, or conversely, a pressure actuated valve such as valve 2 may be used in place of valve 45 and pressure controller 41 of Figure 1.

It will be noted that in result, the system thus far described is identical with the corresponding portion of the system illustrated in Figure 1, that is, when the system is operating on the heating cycle, heat will be transferred from the condenser and the engine to the air stream by the coils'l' and 8', and during this time the water circulation system will remain closed unless the pressure of the compressed refrigerant becomes excessive, at which time water from an outside source will be supplied to the system for cooling the condenser and the engine.

The exhaust manifold 52 of the engine 5| in this embodiment of the invention is connected by means of a pipe-2l5 to the inlet of a threeway valve 2|6. One outlet of the three-way valve 2|6 is connected by a pipe 2|! to the exhaust heating coil 0' and the outlet. of this coil is connected by a pipe 2|8 to the inlet of a second three-way valve 2| 9. The other outlet of the three-way valve 2|6 is connected by a pipe 220- to the pipe 2|8 and thus provides a by-pass for the exhaust gases around .the heating coil 0'. The three-way valve 2| 6 is controlled in exactly the same manner as the corresponding valve 15 of Figure 1. Thus at the time that valve I5 of Figure 1 would be open, the three-way valve 2l6 would be positioned so as to pass the exhaust grses through the heating coil 5'. At the time that valve 15 of Figure 1 would be closed, however, the three-way valve 2 ll would be positioned so as to by-pass the exhaust gases around the heating coil 9.

One outlet of the three-way valve I9 is connected by a pipe 22l to a heating coil 222 which may be located, within a domestic water tank 223. The outlet of this heating coil may be connected by a pipe. 224 to a sewer or chimney. The other outlet of the three-way valve 219 is' connected to a by-pass pipe 225'which leads directly to the exhaust pipe 224. The three-way valve 2l9 may be controlled in accordance with the temperature of the domestic water by means of a temperature controller 226 which may be of the same type as the controller 8| of Figure 1. This controller will position the valve 219 in a manner to cause the exhaust gases to be passed through the heating coil 222 so long as the temperature of the water is not excessive. When the domestic water temperature becomes excessive, however, the controller 226 will cause the three-way valve 2l9 to be positioned in a manher to by-pass the exhaust gases around the heating coil 222. While I have shown the domestic hot water heater as receiving exhaust gases which have been passed through the air stream heating coil 9', it will be understood that if desired the exhaust gases may be first passed through the domestic water heating coil before passing to the air stream heating coil 9.

The controls for the system of Figure 2 may be identical with the controls described in detail for the system of Figure 1. Hence, no further description of this figure is necessary. In this case, however, it will be noted that the floating control of the area of the heating coils in accordance with the demand for reheat is not obtained, the heating coils either being entirely on or off.

Figure 3 In Figure 3, I have shown a modified arrange ment for heating the air stream by exhaust heat from the engine and for heating domestic hot water. This arrangement may be employed for heating the air stream of a heating system or it may be employed for reheating in a cooling system, or both. For purpose of illustration, this arrangement is illustrated in conjunction with a simple summer air conditioning system.

Reference character 230 indicates a compressor which may be driven by an internal combustion engine 23I. The compressor 23! is connected to a condenser 232, which in turn is connected to an expansion valve 233 at the inlet of a cooling coil 234 which is located within the conditioning chamber I, the outlet of this cooling coil being connected to the compressor intake by means of a pipe 236.

The exhaust manifold 236 of the engine is connected by a pipe 231 to heat exchanger 233. L- cated within the heat exchanger 233 may be a The pipe 249 leading from the outlet of the coil 239 is also connected to a pipe 246 which leads-to a heating coil 246 which may be located within a domestic hot water tank 241. The outlet of coil 246 is connected by means of a conduit 248 to the inlet of coil 239 of heat exchanger 233. Interposed in, conduit 249 is a valve 249. This valve 249 may be controlled by means of a thermostat 259 which is responsive to the temperature of the domestic water. So long as the water temperature is below a predetermined value, the controller 250 will cause the valve 249 to be energized for thereby maintaining said valve open. However, when the space temperature becomes excessive, the controller 250 will deenerglze valve 249 for allowing this valve to close.

From the foregoing, it will be seen that the

coils

239, 2 and 246 form a closed heat transfer system. This system is charged with a volatile heat transfer medium. When the

valves

243 and 249 are open, condensed heat transfer medium will flow from the coils 2 and 246 into the coil 239 in which it will evaporate and pass back to the

coils

241 and 246 for thereby heating the air and the domestic hot water. If the valve 243 is closed, however, the condensed heat transfer coil 239, the upper end of which may be con-' nected to a pipe 243 which leads to the inlet of a heating coil 24! located within the conditioning chamber I. The outletoi' this coil is connected by a conduit 242 to the inlet of the coil 239. Interposed in 243 which may be-of the electrically actuated type. The valve 243 .may be controlled if desired by means of a low limit space temperature controller 244 which may be of any desired tim and which is arranged to energize the valve 243 whenever the space temperature falls to a predetermined low value.

the conduit 242 is a valve medium will be prevented from leaving the coil 24! and consequently this coil will fill up with condensed heat transfer medium which will prevent further heating of the air stream.

By the arrangement just described, the effective heating area of the reheat coil 24! will be varied in accordance with the demand for reheat. Upon a call for reheat, the thermostat 244 will cause an opening of the valve 243 which will allow the condensed heat transfer medium to slowly trickle from the coil 2 which will empty 3, portion of this coil and permit vapor from the coil 233 to flow into this portion of coil 2 The rate of flow of condensate from coil 2 may be restricted when valve 243 is open by means of an orifice plate or valve device such as at 242a, or this result may be obtained by properly sizing the condensate return pipe 242. If the demand .for reheat is relatively light, this small portion in the thermostat 244 again opening the valve 243, allowing more condensed heat transfer medium to flow from the coil 2. If the demand for reheat becomes heavy, the space temperature will not rise as soon as it would if the demand were lighter and consequently more condensed heat transfer medium will be allowed to flow from the coil-24l This will increase the effective area of the coil 24I and will cause this coilto supply a greater amount of reheat to the space. It will thus be seen that this arrangement provides for automatically varying the eifective heating surface of the reheat coil 2 in accordance-with the demand for reheat. While no receiver has been shown, it will be unders tions where the return lines do not have suiilcient volumetric capacity to store the necessary volume of liquid. a receiver may be provided in the return lines for providing the necessary storage space.

. It will be apparent that the action of the domestic hot water heating coil will be similar to that of the reheat coil 2. In other words, when that in installathe domestic water requires heating, the valve 249 will be opened thus allowing the condensed heat transfer medium to fiow from the coil 246 for thereby permitting this coil to heat the domestic water. When the domestic water is heated sufliciently, however, the valve 249 will be closed which traps condensed heat transfer medium in the coil 246 for thereby causing it to fill up, which will stop its heating effect.

The engine 23| may be controlled in any desired manner and is preferably controlled by means of a temperature controller 25l and a humidity controller 252, these controllers being arranged to control a proportioning motor 253 which actuates the engine throttle valve 254. The wiring between the controllers 25l and 252 and the proportioning motor 253 is substantially the same as indicated in Figure 1, and accordingly, is not described here. By this arrangement,

the engine speed will be increased upon an increase in either temperature or humidity and the engine will operate if either the temperature beco'mes excessive or the humidity becomes excessive. In the event that the humidity is excessive while the temperature is fairly low, the

operation of the cooling coil for dehumidifying will tend to reduce the temperature of the air. The reheat control arrangement just described, however, will act to prevent this action and supply just sufficient reheat as to maintain the air temperature substantially constant.

In the foregoing description, definite values of temperature and humidity have been mentioned in order to clearly set forth the operation of the control system. These values, however, may be varied for difierent installations and are not to betaken as limiting.

From the foregoing detailed description, it will be apparent that I have provided a novel air conditioning system and control system therefor which acts to either cool or heat a space and which provides for automatic control of temperature and humidity. It will also be seen that my system provides for heating the space during ordinary weather by means of a refrigeration system operating upon the reverse cycle, and adds to the heat procured in this manner, the waste heat from the engine which drives the compressor thereby securing extremely economical operation. It will also be seen that my improved system provides for supplementing the action of the reversed cycle system or for replacing its action by means of an electric or other type of loading means for the engine, which acts to supply additional heat to the space and to cause the engine to supply additional waste heat. Also it will be noted that my invention provides for supplying heat from an auxiliary heater to the space whenever the intemal combustion engine system is incapabl of carrying the heating load. Due to this arrangement, the internal combustion engine system need not be made sufficiently large to carry the peak heating loads which occur for only a very small portion of the heating season.

While I have shown and described several embodiments of my invention," it is obvious that many other modifications of the system and subcombinations thereof which are within the scope of my invention will occur to those skilled in the art, I therefore desire to be limited only by the scope of the appended claims as construed in the light of the prior art.

I'claim as my invention:

1. In an air conditioning system for heating and cooling a space, in combination, a reversible cycle refrigeration system adapted for selectively heating or cooling a space, said refrigeration system having a compressor, an internal combustion engine for driving the compressor, means for placing said internal combustion engine into operation upon demand for either heating or cooling, means for transferring waste heat from the engine to said space, first control means for controlling the transfer of waste heat, second control means for reversing said refrigeration system, and temperature responsive means acting upon fall in temperature to actuate said first control means for supplying waste heat to the space and acting upon a further drop in temperature to actuate said second control means to reverse the system from cooling to heating.

2. In an air conditioning system for heating and cooling a space, in combination, a refrigeration system adapted for cooling a space, said refrigeration system having a compressor, an internal combustion engine for driving said com pressor, means for placing said internal combustion engine into operation upon demand for either cooling or heating, control means for rendering said refrigeration system effective or ineffective to cool said space, means for transferring jacket heat of the internal combustion engine to said space, control means for controlling the transfer of said jacket heat, means for transferring exhaust heat of said engine to said space, control means for controlling the transfer of said exhaust heat, and means for sequentially actuating said refrigeration system control means, said jacket heat transfer control means,

and said exhaust heat transfer control means in a manner to first place at least one of said heat transferring means into operation and then render the refrigeration system ineffective to cool the space.

3. In an air conditioning system for heating and cooling a space, in combination, a reversible cycle refrigeration system adapted for selectively heating or cooling a space, said refrigeration-system having a compressor, an intemal combustion engine for driving the compressor, means for placing said internal (combustion engine into operation upon demand for either heating or cooling, control means for reversing said refrigeration system, means for transferring jacket heat of the internal combustion engine to said space, control means for controlling the transfer of said jacket heat, means for transferring exhaust heat of said engine to said space, control means for controlling the transfer of said exhaust heat, and means for sequentially actuating said refrigeration system reversing means, said jacket heat transfer control means, and said exhaust heat transfer control means in a manner to first place at least one of said heat transferring means into operation and then to reverse said refrigeration system from cooling to heating.

4. In an air conditioning system for heating and cooling a space, in combination, a refrigeration system adapted forcooling a space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, means for placing said internal combustion engine into operation upon demand for loading the engine to increase the waste heat output of said engine, control means for said additional load means, and sequential control means acting to sequentially place said waste heat transferring means into operation, to render said refrigeration system ineffective to cool the space, and to place said additional load means into operation.

5. In an air conditioning system for heating and cooling 9. space, in combination, a refrigeration system adapted for cooling a space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, means for placing said internal combustion engine into operation upon demand for either cooling or-heating, control means for rendering said refrigeration system effective or ineffective to cool said space, means for transferring waste heat from said engine to said space, control means for controlling the transfer of waste heat, additional load means for said engine for loading the engine to increase the waste heat output of said engine, control means for said additional load means, auxiliary heating means for supplementing the heat supplied by the system, control means for said auxiliary heating means, and means for actuating said control means in sequence.

6. In an air conditioning system for heating a space, in combination, a reverse refrigeration system including a heat exchange device in heat exchange relationship with the space for transferring heat from a heat source of low temperature level to said space at a higher temperature for heating the space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, heat exchange means separate from said first heat exchange device for transferring waste heat from said engine to said space for supplementing the action of said reverse refrigeration system in heating said space, and means for controlling the speed of said engine in accordance with the demand for heat of said space.

7. In a system for heating a space, in combination, a refrigeration system adapted for transferring heat from a heat source at a low temperature level to said space at a higher temperature for heating said space, said refrigeration system having a compressor, driving means for said compressor, means for supplying waste heat from said driving means to said space, additional means for loading said driving means heat and waste heat to be insufficient to heat said space to the desired temperature.

9. In a system for heating a space, in combination, a refrigeration system adapted for transferring heat from a heat source at a low temperature level to said space at a higher temperature for heating said space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, means for supplying waste heat from said engine to said space, means for increasing the waste heat output of said engine, and temperature responsive means for placing said last mentioned means into and out of operation.

10. In an air conditioning system, in combination, a conditioning chamber through which air is adapted to be passed for a conditioning action, a heating device in said chamber, said heating device having an inlet for vaporized heat transfer medium and an outlet for condensed heat transfer medium, a vapor generating device, means for connecting said vapor generating device to said heating device, valve means on the outlet of said heating device for trapping condensed heat transfer medium in said device to thereby reduce the portion of said heating device which is effective for heating the air, means for restricting flow of condensed heat transfer medium from said heating means when the valve means is open, and thermostatic means for controlling said valve means.

11. In an air conditioning system, in combination, a reversible cycle refrigeration system having a condenser, an inside evaporator for cooling the space, an outside evaporator for absorbing heat for delivery to said condenser, a compressor, valve means for selectively connecting said inside evaporator or said outside evaporator to said condenser and compressor,

thereby to increase the amount of waste heat,

said additional means acting to also supply heat to the space, and means for placing said additional loading means into operation only when the heat demand for said space exceeds a pre determined value.

8. In a system for heating a space, in combination, a refrigeration system adapted for transferring heat from a heat source at a low temperature level to said space at a higher temperature for heating said space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, means for supplying waste heat from said engine to said space, additional loading means for said internal combustion engine, said additional load-I ing means acting to increase the waste heat output of said engine, and means for placing said additional loading means into operation when the temperature of said heat source falls so low as to cause the combined refrigeration system an internal combustion engine for driving said compressor, a heat transfer system for cooling said engine and condenser, a heat transfer circuit for transferring heat from said heat transfer system to a space being conditioned, control means for controlling said engine and said valve means in a manner to condition said refrigeration system for heating in winter and cooling in summer, and for placing said engine in operation upon demand for either heating or cooling, means influenced by said control means for passing outside cooling medium into said heat transfer system for cooling the engine and condenser during summer operation while maintaining said heat transfer system closed during winter operation, additional ,load means for loading the engine to increase the waste output thereof, and means actuated by said control means for placing said additional load means into and out of operation.

12. In an air conditioning system, in combination, a conditioning chamber through which 1 air is adapted to be passed for a conditioningf heating device for trapping condensed heat transfer medium in said heating device to thereby reduce the portion of said heating device which is eifective for heating the air, means for restricting the flow of condensed heat transfer medium when the valve means is open, and thermostatic means for controlling said valve means.

13. In an air conditioning system, in combination, a. conditioning chamber through which air is adapted to be passed for a conditioning action, a refrigeration system having a cooling and dehumidifying means in heat exchange relationship with the air flowing through said chamber for cooling and dehumidifying the same, a

compressor for said refrigeration system, an

internal combustion engine for driving said compressor, a reheater for reheating the air leaving said cooling and dehumidifying means, a vapor generator receiving heat from the internal combustion engine, means for conveying vapor from the generator to the reheater, a conduit for returning condensate from the reheater to the generator, valve means for controlling circulation between said generator and said reheater, means responsive to excessive humidity for placing said cooling and dehumidifying means into operation, and a thermostat responsive .to demand for reheat for controlling said valve means.

14. In an air conditioning system, in combination, a conditioning chamber through which air is adapted to be passed for a conditioning action, a refrigeration system having a cooling and dehumidifying means in heat exchange relationship with the air flowing through said chamber for cooling and dehumidifying thesame, a

compressor for said refrigeration system, an internal combustion engine for driving said compressor, a reheater for reheating the air leaving said cooling and dehumidifying means, a vapor generator receiving heat from the internal combustion engine, means for conveying vapor from the generator to the reheater, a conduit for returning condensate from the reheater to the generator, a valve in said conduit for trapping condensate in said reheater for thereby varying the efiective heain'ng area of said reheater, a thermostatic controller, a humidity controller, one of said controllers controlling said cooling and dehumidifying means and the other of said controllers controlling said valve means.

15. In a system for heating a space, in combination, a refrigeration system adapted for transferrlng heat from a heat source of low temperature level to said space at a higher temper-' ature level for heating the space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, heat exchange means for delivering waste heat from the engine to said space, additional loading means for loading said engine, and thermostatic means responsive to the demand for heat of said spacefor starting said engine in response to an initial demand for heat, for increasing the engine speed as the demand for heat increases, and

for placing said additional loading means into operation upon further increase in heat demand.

16. In a system for heating a space, in combination, a refrigeration system adapted for transferring heat from a heat source of low temperature level to said space at a higher temperature level for heating the space, said refrigeration system having acompressor, an internal combustion engine for driving said compressor, heat exchange means for delivering waste heat increase in heat demand.

17. In a system for heating a space, in combination, a refrigeration system adapted for transferring heat from a heat source of low temperature level to said space at a higher temperature level for heating the space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, heat exchange means for delivering waste heat from the crater driven by said engine, an electric heater receiving power from said generator for additionally heating the space, a switch for controlling said electric heater, and thermostatic means responsive to the heat demand for the space for starting said engine in response to an initial demand for heat, for increasing the engine speed in response to increase in demand for heat and for closing said switch to place said electric heater into operation upon further increase in heat demand.-

18. In a system for heating a space, in combination, a refrigeration system adapted for transferring heat from a heat source of low temperature level to said space at a higher temperature level for heating the space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, heat exchange means for delivering waste heat from the engine to said space, a waste heat controller for increasing the waste heat output of the engine, automatic starting means for the engine, a speed controller for said engine, theran initial demand for heat and to increase the engine speed upon an increase in demand for heat, and means for actuating said waste heat controller in a manner to increase the waste heat of the engine when the combined refrigeration system heat and normal waste heat of the enlue is insufiicient.

19. In a system for conditioning a space and providing a supply of heated medium, in combination, a refrigeration system for conditioning the air in said space, said refrigeration system including a compressor, an internal combustion engine for dri g said compressor, automatic starting means for said engine, a speed controller for said engine, thermostatic means responsive to space temperature for controlling said automatic starting means and said speed controller, a heat exchanger for heating said medium, thermostatic means-for supplying waste heat from the engine to said space and to said heat exchanger, a controller for increasing the waste heat from the engine, and thermostatic means for actuating said last mentioned controller for increasing the supply of waste heat from the engine when the normal supply is insuflicient.

20. In a system for conditioning a space and providing a supp y of heated medium, in combination, a refrigeration system for conditioning the air in said space, said refrigeration system including a compressor.

engine for driving said compressor, automatic engine to said space, an electric genan internal combustion I starting means for said engine, a speed controller for said engine, thermostatic means responsive to space temperature for controlling said automatic starting means and said speedcontroller, a heat exchanger for heating said medium means including thermostatic means infiuenced by the demand for heat of said medium for supplying waste heat from the engine to said medium, a controller for increasing the waste heat from the engine, and thermostatic means for actuating said last mentioned controller in a manner to increase the supply of waste heat from the engine when the normal supply is insufficient.

21. In a system for heating a space, in combination, a refrigeration system adapted for transferring heat from a heat source of low temperature level to said space at a higher temperature level for heating the space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, means including a heat exchanger through which exhaust gases of th engine are passed for transferring exhaust heat from the engine to said space, a fuel burner for adding additional gases of combustion to the exhaust gases passing through said heat exchanger, and thermostatic means for placing said burner in operation when the refrigeration system heat and the exhaust heat is insufficient to heat said space.

22. In a system for heating a space, in combination, a refrigeration system adapted for transferring heat from a heat source of low temperature level to said space at a higher temperature level for heating the space, said refrigeration system having a compressor, an internal combustion engine for driving said compressor, heat exchange means for delivering waste heat from the engine to said space, auxiliary heating means for supplying heat to said space in addition to the heat supplied by said refrigeration system and said waste heat, automatic starting means for said engine, a speed controller for said engine, thermostatic means for controlling said automatic starting means and said speed controller in a manner to start said engine upon an initial call for heat and to increase the speed of the engine as the heat demand increases, and means for placing said auxiliary heating means into operation when the combined waste heat and refrigeration system heat is insuflicient to heat said space.

23. In an air conditioning system, in combination, a reversible cycle refrigeration system for heating and cooling a space, said refrigeration system including a condenser for dissipating heat during the cooling cycle and for delivering heat to the space during the heating cycle, a heat exchanger in heat exchange relationship with the space, a normally closed heat transfer circuit between said condenser and said heat exchanger comprising a supply conduit for conveying heat transfer medium from said condenser to said heat exchanger and a return conduit for returning said medium to said condenser, a supply connection for supplying heat transfer medium to said return conduit, a check valve in said return conduit to prevent heat transfer medium admitted from said supply connection from passing through said return conduit to said heat exchanger, and a relief connection in said supply conduit for allowing medium passed into said heat transfer circuit by said supply connection to escape from said heat transfer circuit after passing through said condenser.

ALWIN B. NEWTON.