US2628480A

US2628480A - Combination refrigeration and evaporating cooling unit

Info

Publication number: US2628480A
Application number: US281122A
Authority: US
Inventors: Archie S Feinberg
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-04-08
Filing date: 1952-04-08
Publication date: 1953-02-17
Anticipated expiration: 1970-02-17

Description

Feb. 17, 1953 s FEINBERG 2,628,480

COMBINATION REFRIGERATION AND EVAPORATING COOLING UNIT Filed April 8, 1952 5 Sheets-Sheet l Arch/e S. Fe/nberg INVENTOR.

A TTORNEY Feb. 17, 1953 A. s. FEINBERG COMBINATION REFRIGERATION AND EVAPORATING COOLING UNIT Filed April 8, 1952 5 SheetsShet 2 Arch/e S. Fe/nberg INVENTOR.

A TTORNEY Feb. 17, 1953 A. s. FEINBERG 2,628,480

COMBINATION REFRIGERATION AND EVAPORATING COOLING UNIT 5 Sheets-Sheet 3 Filed April 8, 1952 Archie 5. Feinberg I INVENTOR.

ATTORNEY 2: &

uni x22 30 6 Feb. 17, 1953 A. s. FEINBERG 2,628,480

COMBINATION REFRIGERATION AND EVAPORATING COOLING UNIT Filed April 8, 1952 5 Sheets-Sheet 4 I/PcH/E 6. FE/NBE/Pa INVENTOR.

Feb. 17, 1953 A. s. FEINBERG COMBINATION REFRIGERATION AND EVAPORATI NG COOLING UNIT Filed April 8, 1952 5 Sheets-Sheet 5 III . FE/NBERG' INVENTOR.

ATTORNEY Patented Feb. 17, 1953 UNITED COMBINATION REFRIGERATION AND EVAPORATIN G COOLING UNIT Archie S. Feinberg Dallas, Tex.

. Application Aprira aszfs riaiN .2 s1,122

2 33'Claims.

This invention relates to air conditioningapparatus and more particularlyto, such apparatus employing both refrigerating and evaporative cooling systems.

This application is a continuation-in-part of my co-pending application Serial No. 145,833, filed February 23, 1950, now'abandoned.

The normal summer temperatures in the northern half of the United States seldom exceed 85 degrees Fahrenheit but the relative humidity of the atmosphere is usually relatively high. Refrigerating systems for air conditioning rooms and buildings are largely employed in this northern half of the United States because of the ability of these systems to dehumidify as well as to cool the treated air. Refrigerating systems, however, are costly to operate since large amounts of power are needed to compress and liquefy the refrigerant gas employed in these systems. Prolonged periods of compressor operation are made necessary even during periods when the outdoor atmospheric temperature is as low as '78 to 79 degrees Fahrenheit by the increase in temperature of the air in the air conditioned space due to the heat released in the air conditioned space by human occupants and lights and other heat emitting appliances. This human occupancy heat load, as it is termed in the industry, necessitates operation of the compressor even though the outdoor atmospheric temperature and relative humidity conditions may be such as to be entirely comfortable to human beings. Human occupancy of the air conditioned space not only raises the temperature of the air within the air conditioned space but also raises the relative humidity since water vapor is released by the human occupants through perspiration thus increasing their discomfort. The operation of a refrigeration system is uneconomical during periods when the outdoor atmospheric conditions are comfortable to human beings. The human occupancy heat load can be more economically removed by moving fresh air from the outdoors into the air conditioned space and expelling outdoors the air which has been heated and humidiv fied by the human occupants of the space. The temperature of the outdoor air may have to be lowered a relatively small degree to allow for the gradual warming of the air in its passage through (Glitz- 1)- the outdoorair can be accomplished very-fecoi the air conditioned space due to the heat emitted a predetermined value. This small cooling of nomi'cally by evaporative cooling. v

Control of the temperature and humidity in the conditioned space by evaporative coolingand continuous exchange of air within the air conditioned space is feasible only during periods-- when the dry bulb temperature of the outside air is about 86 degrees Fahrenheit or less and the wet bulb temperature is about '79 degrees Fahrenheit or less. When these atmospheric conditions do not obtain a refrigerating system is needed to cool the air within the air conditioned space. It is desirable, therefore, for economical and satisfactory operation of an air conditioning apparatus that it provide a refrigerating system for use when outdoor temperatures are above degrees Fahrenheit and an evaporative'cooling system for use when outdoor temperatures are 8 5 degrees or lower. By using air conditioning sys-j tems having both systems, the periods of costly. operation of the refrigerating system, are greatly reduced since itop'erates only during'the rela-' tively few and short periods when the dry bulb". temperature of the outdoor air exceeds 85 de-' grees Fahrenheit or the wet bulb temperature exceeds 79' degrees Fahrenheit. The air condi' tioning apparatus must also be capable of con'-. tinuously displacing a greater volume of air during the time the evaporative cooling system is in operation than is necesasry during the time the refrigerating system is in operation. More-. over, in order to meet the needs of varying internal and external conditions the controls of. the air conditioning apparatus should provide for automatic changeover from operation of one sys-l. tem'to operation of the other system upon a 'pre determined change in internal and external 'con-' ditions as well as for selective choice of opera tion of either system. I i

Accordingly, 'it is an object of myin-vention to provide a new and improved air conditioning apparatus. 1

It is another object of my invention to provide a new and improved air conditioning apparatus having a refrigerating system for conditioning air when the outdoor air temperature exceeds a predetermined value and an evaporative cooling system for conditioning air when the outdoor tem perature is less than a predetermined value. 7

It is another object of my invention to provide a new and improved air conditioning apparatus having a refrigerating system including an evap orative condenser provided with a blower'and water spray system and having an evaporative cooling system employing the blower and water spray system of the evaporative condenser of the refrigerating system.

It is another object of my invention to provide a new and improved air conditioning apparatus having a refrigerating system, and an evaporative cooling system, and being provided with means for automatically operating the refrigerating systemwhen. the outdoor ,air.---tem-.

perature exceeds a predetermined. value and for automatically operating the evaporative cooling system when the temperature falls below a pre-.:

determined value.

It is another object of my invention ta-prof vide a new and improved air conditioning apparatus provided with a refrigerating system and an evaporative cooling system and .withlcontrols for automatic changeover from operationof one sys tem to operation of the other system upon,pre-; determined changes in internal and external conditions".

It is still another. object .of, my invention to providea new and improved air conditioning apparatusprovided witha refrigerating system and.

anevaporative cooling system and with controls foriselective choice of operation of either system.

It .isanother object of the invention to provide a new and improved air conditioning appa l ratus having. a refrigerating system for conditioning.,.air when. the outdoor temperature ex-i ceedsa prede'terminedwalue and a system for increasing. the volume of flow of air from the outdoor atmosphere when the outdoor temperature isless than the predetermined value.

Briefly stated, my new and improved air conditioning apparatus. comprises a refrigerating system..and an evaporative cooling system. The refrigeratin system is provided with a compressor ,.for,..compressing arefrigerant, gas. an evaporative condenser .coil in which the, compressed gas is.coole d and liquefied, a ,spraysystem for cooling the evaporative condenser coil by. spraying Water on ..th.e..coi1, acondenserblower for, moving air past the evaporative condenser coil and removing totheoutdoors the. heat released bythe refrig erant gasjn cooling and liquefyingthe refrigerant, a coolingrcoil in which the liquefied gas is allowed to evaporate and expand, and a conditionerblower for moving recirculated and fresh outdoor air past the cooling coil to be cooled and dehumidified by the absorption of heat by the refrigerant gas and into the air conditioned space. The evaporative cooling system employs the spray system and the condenser blower associated with the evaporative condenser coil and includes a duct to move air cooled by evaporation of the spray to the conditioned air space and a damper which selectively directs the flow of the, air past the spray-to the air conditioned space or to. the'oute doors. In operation the refrigerating system is employed when the outdoor temperatureexceeds a predetermined value and the damper is positioned to direct the air moved past the spray to the outdoors. The only air entering the air conditioned space is moved past the cooling coil by the conditioner-blower; The latterair may be partly recirculated air or may be wholly fresh air moved from the outdoors;

During this period the compressor operates as needed. When the temperature falls below a predeterminedvalue, the compressor is maintained inoperative but the conditioner blower remains in operation to move air from the outdoors into the air conditionedspace. The condenser blower associated with'the evaporative condenser coil is also "maintained inoperation and moves air'from the outdoors through the water spray where its temperature is lowered by evaporative cooling and into the air conditioned space, the damper being moved to direct the flow of air from the outdoors to the air conditioned space. During the operation of the evaporative cooling system all blowers may move air from the outdoors and into the air conditioned space, moving. a great volume of air throughthe air conditioned room to remove the human occupancy emitted heat. Only a portion of the air is cooled since the air moved by the cooling coil blowers is not cooled, the compressor being inactive. Controls are provided for automatically controlling the operation of all dampers, compressors, and motors of the air con- "ditioning apparatus to insure that the refrigerating system operates when th temperature of the, outdoor air exceeds a predetermined value and that the evaporative cooling system operates when the temperature falls below a predetermined value.-

Ina modified iormof the invention,- all of theair -moved by the conditioner blower is drawnfrom the conditioned space. In this case, the inflow-of outdoor air through doors or windows into the conditioned space is relied upon to provide the proper proportion of. fresh air to recir'-. culated air during normal operation of the refrigerating system. When-the outdoor temperature does not 'exceed the predetermined Value;- the condenser blower'is employed, as in the first;

described embodiment, to increase the 'rate of flow of outdoor air into the conditioned'space;

Fora better understanding of my invention,- reference maybe had to the following description taken in connection with the accompanying drawing, and itsscope Will be pointed out in the. appended claims.

In the drawingr;

Figure 1 is a schematic diagramofthe air conditioningapparatus:- with all electric circuits omitted;

Figure 2 is a diagrammatic perspective of the air, conditioning apparatus of Figure '1 installed for operation and with all electric circuits omitted;

Figure 3 is a diagrammatic illustration of the control circuits of the air conditioning apparatus of Figures 1 and 2; and,

Figure 4 is a schematic diagram of a modified form of the air conditioning apparatus; and,

Figure 5 is a perspective view'of a building; with the top removed and some walls broken away; provided with another modified form of the air conditioning apparatus.

Referring nowespecially to Figure l, the prine ciple .of operation of a preferred embodiment of my invention is disclosed as employed to maintain comfortable temperature and humidity. C011! ditions in the conditioned space i 0 which may be a room, a series of rooms, or an entire building. The air conditioningapparatus, comprises a refrigerating system and an evaporative cooling system.

Refrigerating system The refrigerating system comprises a cooling section I l,'a compressor section I2, and an evaporative condenser section l3 as in conventional refrigerating systems. Air is forced into the space I!) by a blower l4 operated by a prime mover, such as .an electric motor I5. The air is drawn through a duct H5 in which is disposed a cooling coil H which is maintained at a low temperature by the evaporationof a refrigerating gas, such as ammonia'or Freon: Heat is absorbed by the refrig- 5. crating gas from the air drawn past the cooling coil l1 and the temperature of the air forced into space I is lowered. A certain amount of the water vapor contained in the air is condensed on cooling coil El and drains into drain pan I3. Removal of this water vapor dehumidifies the air forced into space H) and renders air condi-- tions more comfortable for human occupants of space W.

The evaporated refrigerating gas is compressed by the compressor l9 which is driven by a prime mover, such as an electric motor 2|]. The compressed refrigerant gas then moves to the condenser coil 21 where the heat of compression and the latent heat of condensation are removed by evaporative cooling and the refrigerant gas is liquefied. Condenser coil 2| is disposed in an air duct 22 and is cooled by the evaporation of water sprayed over coil 2| by a water pump 23 through a spraying means, such as a spray pipe 24. Air is moved from the outdoors 25 past compressor l9, compressor motor Zil, and condenser coil 2| to remove the heat emitted by motor 20, compressor l9, and the heat of compression and condensation of the refrigerating gas in condenser coil 2|. After moving past condenser coil 2|, the air is humid as well as warm since a portion of the water sprayed over condenser coil 2| is evaporated upon coming in contact with the warm condenser coil 2 l. The air is moved through duct 22 and out into the outdoors 25 through an air duct 26 by condenser blower 21 driven by a prime mover, such as an electric motor 28. Electric motor 28 also drives water pump 23 which pumps water from pan 29 which collects the water sprayed by spray pipe 24 which has not been evaporated. Water may be supplied to pan 29 by any conventional means, not shown, so that water will always be present in pan 29.

It will be apparent that heat is extracted by the evaporating refrigerant gas in cooling coil H from the air moving through air duct It into space H], the refrigerating gas then being compressed by compressor [9 and liquefied in condenser coil 2|. The heat extracted by the evaporating refrigerant gas in cooling coil I1 is released by the refrigerant gas in condenser coil 2| to the air moving past condenser coil 2| and is passed to the outdoors with the air moving through duct 26. The degree of cooling of the air moving through duct It depends on the amount of refrigerating ga allowed to evaporate in cooling coil I! per unit of time and this depends in turn on the amount of the liquefied refrigerating gas allowed to flow from condenser coil 2i to the expansion valve 3% where the liquefled refrigerant gas evaporates, cools in evaporating, and passes into the cooling coil In order to maintain a predetermined temperature in space H], the flow of liquefied refrigerating gas to expansion valve 30 is controlled by a conventional solenoid valve 3| which is controlled by a thermostat 32 located in space It. If the temperature of the space H! tends to rise, thermostat 32 will cause solenoid valve 3| to allow more liquefied refrigerant gas to pass to expansion valve 30, more heat will be absorbed from the air assing through duct is, and the temperature of the air in space Ii! will be lowered.

Operation of compressor motor 28 is controlled by a low pressure switch 33 and a high pressure switch 34 for automatically maintaining proper refrigerating gas pressures in cooling coil I7 and condenser coil 2|. Compressor motor 23 is started automatically Whenever the pressure of predetermined value and is stopped whenever the pressure in the cooling coil I! falls below a D determined value or whenever the pressure of the refrigerant gas in condenser coil 2| exceeds a certain predetermined value.

Switches

33 and 34 insure that a sufficient amount of the refrigerant gas is always in a liquid state and also prevent the building up of an excessively high pressure in condenser coil 2| and an excessively high or excessively low pressure in cooling coil 11.

As shown in Figures 1 and 2, all the air moved past cooling coil I! may be drawn from the outdoors 25 through ducts 35 and 35a or part of the air may be moved from the outdoors 25 through duct 35 and part of the air may be moved from space H] through duct 36. The position of recirculation damper 31 determines whether'only fresh air from the outdoors is moved into space I!) or whether a portion of the air in space 10 is recirculated through duct 36. In the position of recirculation damper 31 shown in Figures 1 and 2, both fresh air and recirculated air is being moved into space It. A damper 31a provided with a handle 31b may be provided in duct 35a to close duct 35a when no fresh air and only recirculated air is to be moved into space Hi. This may be desired when the outdoor air i intensely hot to avoid excessive operation of the refrigerating system. Damper 31 is moved by any suitable prime mover such as electric damper motor 38 which may be linked to damper 31 in any conventional manner such as the sprocket and chain means 38a illustrated in Figure 2.

It will be noted that duct 36 is roughly four times the size of duct 35 in cross section. This disparity in size causes the air moved by conditioner blower I4 to be about percent recirculated air and about 20 percent fresh air when damper 3'! is positioned to allow a minimum of fresh air to be moved into space H]. This ratio of recirculated air to fresh air is usually employed in operation of refrigerating systems for air conditioning.

Evaporatz'ue cooling system The evaporative cooling system of my air conditioning apparatus makes use of air duct 2 water pump 23 and spray pipe 24, condenser blower 21, and motor 28 of the refrigerating system. If the condenser coil 2| is not heated by the action of the refrigerating gas compressed by compressor l9, air moved by condenser blower 21 through the water spray caused by spray pipe 24 is cooled by the evaporation of the sprayed water since the evaporating water absorbs heat from the air. In order to move the air cooled by the'wa-f ter spray produced by spray pipe 24 into space I0, I provide a condenser damper 3'9 and an air duct 40 communicating with space I0 and also with duct 22, when damper 39 is moved to the broken line position 4| of Figure 1. Condenser damper 39 is actuated by any suitable prime mover such as electric damper motor 42 and is linked to motor 32 by any conventional means, such as the sprocket and chain means 42a. Damper motors 38 and s2 are of the geared-down type conventionally employed for this purpose and will move their respective dampers 31 and 39 in either direction depending on the manner in which their controls are operated.

Damper motors

38 and 42 will move the dampers 3! and 39 until the dampers are stopped by obstructions such as stops 42b. Condenser damper 39 is actuated by any suitable prime mover, such as electric damper motor. 42:. and is linkedto motor 42- by-any con-; ventional-meanssuch as the sprocket and chain means 42a.

In operation of the air conditioning apparatus, it -is desirable that the refrigerating system functiorronly when the dry bulb temperature of the outdoor air exceeds a predetermined value, say 85 degreesFahrenheit. It is also desirable that it functionv even when the dry bulb temperature is 85 degrees or less if the wet bulb temperature of the outside air, which is an indication of the humid condition of the air, exceeds a certain predetermined value, say '79 degrees Fahrenheit. Thermostat 43 and 44a responsive to dry bulb temperatureand a thermostat 44 responsive to wet bulb temperature are positioned to measure the outside dry and wet bulb temperatures.

Thermostats

32, 43, 44, 44a and 45a are employed tov control automatically the operation of the air conditioningapparatus and a detailed description of. their associated controls will be given later.

If it is desired to maintain a temperature of '75 degrees'in space H! and the outside temperature is below 75 degrees, it is not necessary to cool the air introduced into space 10 but a certain circulation of air is necessary to maintain comfortable conditions within space It. A selector switch 45 may be employedto cause only conditioner motor IE to run. .Since the temperature of the outdoorair is below 75 degrees, a maximum of recirculated air and a minimum of the cold outdoor air must be moved through air duct to. The automatic control associated with thermostat 450. cause damper motor 38 to move recirculation damper 31 to the position shown in Figure 1.

When the dry bulb temperature of the outside air is higher than 75 degrees but not higher than 85 degrees Fahrenheit and its wet bulb temperature islessthan 79 degrees, the evaporative coolingsystem is placed in operation by the automatic controls.

Damper motors

38 and 42 move dampers 31 and 39 into the broken line positions 46'and 4|, respectively, and motors l5 and 28 are energized. No recirculated air is allowed to move through air duct 36, fresh outdoor air only mov ingthrough ducts I6 and 40 into space it. Since compressor motor 20 is not energized, the air moving through duct 6 is not cooled. The only cooling taking place is by evaporation of water in air duct 22. During this phase of the operation of the air conditioning apparatus, a maximum volume of .air is moved into and through space Hi sinceboth blowers l4 and 2'! are moving air into space I0.

When. the outdoor dry. bulb temperature exceeds85 degrees or the wet bulb temperature exceeds'79 degrees the refrigerating system is automatically brought into operation. Compressor motor 20 is energized and compressor l9 begins to compress the refrigerant gas, the cooling coil I! therefore causes the air moving through air duct 16 tobe cooled. At the same time damper motors 3B nd 42 are energized and move dampers 3'land 39, respectively, to the solid line positions illustrated in Figure 1. A maximum amount of air is recirculated through air duct 36 and the air. moved by blower 21 is moved outdoors through duct 26, this air now being warm and moist due to the heat it has absorbed in passing past condenser coil 2|. Thermostat 32 now controls solenoid valve 31 to control the degree to Whichthe :air flowingthrough air duct 16 is cooled.

If the dryqbulb temperature of the'outdoor air now falls .1 below degrees while. the wet bulb temperature is lower than 79' degrees, motor 20 is deenergized and

motors

38 and 42 are energized to move dampers 31 and 39 to the dashed line positions 46 and 4|, respectively, the energization of the damper motor 42 is delayed by.

the action of thermostat 45a, however, to allow the water in pan 29 to cool to 79 degrees to avoid motor Hand to preclude-damage to damper 39,

condenser blower2l-is stopped each time damper 39 i moved.

Figure 2 illustrates diagrammatically an actual installation of the air conditioning apparatus illustrated schematically in Figure 1. The apparatus is located in a small room 41 adjacent air conditioned space 10.

Air ducts

35, 35a and 26 lead directly to the outdoors. Duct 2B is so lo cated that the air it discharges cannot find its way into air ducts 35 and 35a since the air discharged by. duct 26 is warmer and more humid than the outdoor air. Fresh air is brought in through ducts 35 and 35a' and flows through the cooling coil l7, through conditioner blower [4, here shown as discharging into duct which leads into space H). The path of flow of the fresh air is indicated by lines 50, 5!, and 52. The recirculated air flows through duct 36, cooling coil ll, conditioner blower l4, and duct 48. The path of flow of the recirculated air isindicated by

lines

53, 5e and 55. The combined flow of fresh and recirculated air is indicated by lines 55 and 51. The air employed to cool the condenser coil 2| when the refrigerating system is in operation flows in through a window 58 or other aperture in room 47, and moves through grill 59 of the air conditioning pparatus past compressor 19, compressor motor 20, condenser coil 2|, spray pipe 24, through condenser blower 21, and to the outdoors through duct 26. The path of flow of thi air is indicated by line 60. When the evaporative cooling system is in operation, this air follows the same path except that condenser damper 39 blocks duct 26 and allows the air to flow through duct 40 into space In.

Automatic. control system In order to obtain maximum efiicienoy of oper-' ation of my air conditioning apparatus under varying conditions of temperature and humidity Ihave provided an automatic control system to operate the various components of my apparatus.

The conditioner motor l5, the compressor motor 23, and the condenser motor 28 are connected in parallel across a four wire three phase supply circuit having leads 6!, 62, 63 and a neutral lead 64. Starting 'contactors 65, 66, and 61 are provided for motors l5, 20 and 28 respectively.

Contactor 65 comprises contacts 68, Hand [0 which connect motor [5 to leads '63, 6| and 62, respectively when the actuating coil II of contactor '65 is energized to start motor I5. An auxiliary contact 12, whose function will be described below, is also actuated simultaneously with contacts-68, 69 and 10 when actuating coil II is energized. C'ontactor B5 is provided with a conventional thermal overload relay which comprises heater coils I3 and I4 connected in series with contacts 69 and I respectively, when the latter are in their actuated positions. The heater coils I3 and I4 allow the thermal overload contact I5 to open the circuit of actuating coil it when excessive currents are drawn by conditioner motor I5. Since the contact I5 opens the circuit of coil II, coil II is deenergized and contacts 68, 69 and I0 return to the non-actuated positions illustrated in Figure 3 and contitioner motor I5 is stopped.

Contactor 61 similarly comprises three contacts TI, 18 and 19 which connect condenser motor 28 to leads 63, BI and 92, respectively when the actuating coil 80 is energized to start motor 28. An auxiliary contact SI, whose function will be described below, is also actuated simultaneously with contacts ll, I8 and I9 when actuating coil 80 is energized. C-ontactor 6! is also provided with a conventional thermal overload relay comprising heater coils 82 and 83 connected in series with contacts I8 and I9, respectively, when the latter are in their actuated positions. Heater coils B2 and 03 operate thermal overload contact 84 to open the circuit of actuating coil 89 and stop condenser motor 28 when condenser motor 28 draws currents of overload intensity.

Contactor 65 similarly comprises three contacts 85, 86 and 81 which connect compressor motor 29 to leads 63, BI and 62 respectively, when the actuating coil 88 is energized to start compressor motor 20. An auxiliary contact 89, whose function will be described below, is also actuated simultaneously with contacts 85, 86 and 97 when actuating coil 89 is energized. Contactor E8 is also provided with a conventional thermal overload relay comprising heater coils 99 and 9|, connected in series with contacts 86 and 81, respectively, when the latter are in their actuated positions. Heater coils 86 and 81 operate thermal overload contact 93 to open the circuit of actuating coil 80 and stop compressor motor 20 when compressor motor 20 begins to draw current of overload value.

In order to provide automatic operation of the air conditioning apparatus, I provide

thermostats

32, 43 and 44a which are responsive to temperatures of air as measured by a dry bulb thermometer and which will be referred to hereinafter as dry bulb thermostats to distinguish them from thermostat 44 which is responsive to the temperature of air as measured by a wet bulb thermometer and which will be referred to hereinafter as a wet bulb thermostat. I also provide a thermostat 45a located in the water pan 29 and responsive to the temperature of the water in pan 29. Thermostat 32 is preferably located at a position in space I0 where it will be exposed to air having a temperature equal to the average temperature of the air within space I0.

It is sometimes desirable to run only the conditioner blower I4 to maintain a certain circulation of air within the air conditioned space I0 without cooling any air. At other times it may be desired to run either solely therefrigerating system or the evaporativ-e cooling system of my apparatus. Lastly, it is usually desirable to operate either the refrigerating system or the evaporative cooling system as dictated by the temperature and humidity conditions of the outdoor air and to have the change from one system to the other made automatically.

,In order to allow a choice to be made of any of the above four methods of operating the air conditioning apparatus, I provide a four position erate; when in position B, either the refrigerating system or the evaporative cooling system will operate, the automatic controls dictating' the choice of the system to operate; when in position C, solely the evaporative cooling system will function, and when in position D, solely the refrigerating system will function.

A double pole single throw toggle switch 9-4 is located adjacent selector switch 45 and must be closed before the air conditioning apparatus will operate. In addition, a time clock which operates a contact 96 may be used to insure that the air conditioning apparatus will operate only during a stated period of the day, for example between 8:00 a. m. and 5:00 p. m. During this period time clock 95 will maintain contact 96 in actuated position connecting relay winding 91. across leads 6| and 53 through conductors 99 to I04. When relay winding 91 is energized it moves contacts I55 and I06 to their actuated positions connecting conductors I01 and I08 to conductors I09 and 99, respectively.

Conditioner blower only operation Assuming now that time clock 95 has moved contact 96 to actuated position, that as a result contacts I05 and I06 are in their actuated positions, and that selector switch 45 is in A position to permit the operation only of conditioner blow er I4, closing of toggle switch 94 will connect contactor coil TI across leads 6| and 63 through conductors I02, II9, III, thermal overload contact 75, conductor I09, contact I05, conductor I0'I, blade I I2 of toggle switch 94, and conductors I08, 99, I00, and IOI. Since contactor coil 'II is energized, contacts 68, 69, I0 and I2 are actuated and conditioner motor I5 now operates to drive conditioner blower I4.

It is desirable that a minimum of fresh air be brought in from the outdoors when the outdoor temperature i below 75 degrees in order to prevent the air in space It from becoming toocold. Conditioner damper 31 must, therefore; be brought to the position shown in Figure 1 in order to allow a maximum of air to be drawn from space I0 and recirculated through air ducts 36 and I9 back into space I0. Damper motor 38 is connected across neutral lead 64 and lead 63 through conductors IOI, I00, contact I2, and conductors H3, H4 and H5 at the same time motor I5 is connected across leads BI, 62 and 63. Damper motor 38 is controlled by conductors H6 and III which causes damper 31 to move to the position shown in Figure 1 when they are short circuited by contact I I8 of thermostat 44a. Since the thermostat 440. short circuits conductors II6 and II? when the outdoor temperature is below '75 degrees, damper 3'5 will always be in the position shown in Figure 1 when the outdoor temperature is below 75 degrees, allowing maximum recirculation of the air from space I0 and allowing a minimum of fresh air to be brought into space I0 from the outdoors 25.

' At the same time that actuator coil II is energized, the coil IIQ of circuit breaker relay I20 is also energized since it is connected across leads 63 and 6| through conductors I00 and 99, contact I06, conductor I98, blade I2I of switch 94, conductor I22, the rotary contact I23 of selector switch 45 and conductor I24. When coil H9 is energized, contact I25 disconnects conductors I26 and I2? so that conductors II! and H6 will not be short circuited when contact II8 of thermo' Damper controls The control circuit of damper motor '42 are closely associated with the control circuits of damper motor '38 and they will be described in conjunction with the description of damper motor 38. Damper motor 42, like damper motor 38, is connected across neutral lead 64 and lead 63 when actuating coil 1| is energized. Damper motor 42 is connected across leads 64 and 63 through conductor I00, contact 12, and conductors '4, I28 and I29. Damper motor 42 is controlled by conductors I21 and I30. Damper 39 is "moved to the position indicated in Figure 1 when conductors I21 and I30 are short circuite'd either by the contact I 3| of damper position relay I32 or by the contact I33 of thermostat 45a. When the outdoor temperature is above '15 degrees, contact IIB of thermostat 44a connects conductor II1 to conductor I26. If at the same time contact I25 of circuit breaker relay I20 i in its non-actuated position, conductors I21 and I26 are also connected. Since conductors H6 and I30 are permanently connected at common connection I34, the control conductors H6 and H1, and I21 and I30 of damper motors 3 8 and 42, respectively, are connected in parallel. The internal resistance of each

damper motor

38 or 42 being relatively great, neither acts as a short circuit for the control conductors of the other. Contacts I3| and I33, therefore, short circuit both control conductors II 6 and I I1 and conductors I21 and I30 when either is moved to its actuated position and both dampers 31 and 39 are moved to the dashed line positions 46 and 4|, respectively, shown in Figure 1. In this position damper 31 will not permit air'to be recirculated from space I0. Damper 39, when in 'the position 4 I will direct the air moved by blower 21 into space I0. It will be noted that both dampers 31 and 39 will be moved simultaneously except when the outdoor temperature is less than '75 degrees or contact I25 of relay I20'is in its actuated position.

The actuating coil I35 of damper position relay I32 is connected across the solenoid coil I36 of the solenoid valve 3| to insure that damper 31 will be in position to allow a maximum recirculation of air to space I0, and to insure that damper 39 'will be in position to divert all air moving past condenser coil 2| to the outdoors when the refrigerating system will of necessity be in operation since actuation of solenoid coil I36 will allow refrigerant gas to enter cooling coil I1 and low pressure switch 33 will cause compressor motor 20 to operate. In order to avoid operationof damper motors "38 and 42 each time the solenoid coil I36 is energized, thermostat 45a is placed in Water pan 29. As long as the temperature'of the "Water in pan 29 is above 79 degrees, contact I33 will remain in its actuated position connecting conductors I21 and I30 and dampers 31 and 39will remain in the positions shown in Figure 1. The period during which the solenoid coil is not energized should be made short enough that the refrigerating system will operate again before the water in pan 29 cool below 79 degrees. Thewater inipan 29"willthen be sprayed over cdnden'se'rcoil z'rana again heated by the compressed and liquefying refrigerant gas. However, if the water in pan 29 should cool to less than '19 degrees before solenoid coil I36 is again energized, dampers 31 and 39 will move to positions shown by dashed lines 46 and 4|, respectively, and a moments delay will occur between the time solenoid coil I36 is again energized and the time compressor I9 again is operated by motor "20. This delay is caused by switch I31 whose function will'be described presently.

If damper 39 is moved from one position to another while condenser motor 28 and condenser blower 21 are in operation, the movement of damper 39 is impeded by the pressure of the air driven by blower 21. A large damper motor 42 Will have to be employed to overcome this pressure and insure smooth movement of damper 39. I provide a damper position switch I 31 which deenergizes contactor coil of starting contactor 61 and stops condenser motor 28 and blower 2| each time damper 39 changes position. Switch I31 is provided with a pivoted blade I38 having an insulated end I39 engaging damper 39. At the initiation of movement of damper 39, insulated end I39 is engaged by damper 39 causing blade I38 to open the circuit of contactor coil 80 by disconnecting conductor I40 from conductor I41. As damper 39 approaches the end of its travel, conductors I40 and I4'I "are again connected by blade I38 and contactor coil 80 is again energized to start condenser motor 28 and operate condenser blower '21. Since actuator coil 88 of compressor motor 20 is energized through con? tact 8| of starter contactor 61, operation of compressor I9 is also interrupted or delay each time damper 39 changes its position.

Condenser and compressor control The condenser motor 28 and the compressor motor 20 are controlled through their starting contactors 61 and 66, respectively, by low pressure relay 33 which is opened when the pressure in the cooling coil I 1 falls below a predetermined value and which is closed when the pressure in cooling coil I1 rises above a predetermined value, a high pressure relay 34 which is normally closed and Which is opened when the pressure in condenser coil 2| reaches a predetermined high value, a single pole relay I42, and damper position switch I31.

The actuating coil 80 of condenser motor 28 is connected across leads 63 and 6| through thermal overload contact 84, conductor I40, blade I38 of damper position switch I31 when damper 39 is in either of its opposite positions, conductors |4|, I43 and I44, contact I45 of relay I42 when it is in its actuated position, contact I46 of low pressure relay 33 when it is in its actuated position, conductors I41 and. II3, contact 12 of starter contactor 65, and conductor I00. Contact I45 is actuated to closed position when its actuating winding I53 is connected'across leads 63 and 6| when contacts 12 and I46 are both closed through conductors I00, contact- 12, and conductors H3 and I41. Condenser motor 28 therefore operates whenever the pressure in cooling coil I1 rises to above a predetermined value and contact I46 is actuated, provided that damper 39 is in either of its opposite positions.

When contactor coil is energized, it 'ac'tuates contact 8| of the starting actuator 61 connecting contactor coil 88 across leads 6| and 63 through conductor I46, thermal overload contact 93, conductor I49, "contac't'8l, contact I50 of highpressure 'relay3 4, contact "I46; conductors I41 and I' I3,

"13 contact I2 and conductor I00. Compressor motor 28 will therefore operate whenever conditioner motor I and condenser motor 28 operate provided the low pressure relay contact I46 and the high pressure relay contact I56 are both in closed positions.

t is desirable that the compressor motor continue to operate until it is turned oil? by the opening of contact I43 of the low pressure relay even though during its operation either toggle switch 9 3 or time clock 95 contact 96 is opened to stop operation of the air conditioning apparatus in order to prevent a relatively high pressure in cooling coil I? which may lead to malfunctioning of the refrigerating system as will be explained below. The contact 39 of contactor 66 connects contactor coil II of conditioner motor I5 across leads (H and 63 through conductors I5I and I52, thermal overload contact "I5, and conductor III]. The conditioner motor I5 and condenser motor 28 will therefore continue to operate even though switch 94 or contact 96- is opened until the contact I 36 of low pressure switch 33 opens.

If the pressure in condenser coil 2| exceeds a predetermined value while contact M6 is still in its closed position, contact I56 of high pressure switch 3 will open deenergizing contactor coil 88 and stopping compressor motor 26. Condenser motor 23, however, will continue to operate so that condenser coil 2| will be cooled by the water sprayed by pump 23 and by the air blown by blower Z'l to reduce the pressure. When the pressure falls below the predetermined value, contact I56 will close again and compressor motor 26 will also operate again until either contact I46 of the low pressure switch 33 or the contact I56 of the high pressure switch 36 will open.

When contact I66 of low pressure switch 33 opens, both compressor motor 23 and condenser motor 28 are stopped since actuating winding I53 of relay I42 is deenergized and contact M5 is opened.

Refrigerating system operation only If the rotary blade I23 of selector switch 35 is moved to position D, only the refrigerating system will operate. It is sometimes necessary to operate only the refrigerating system even though the outdoor temperature conditions call for operation of the evaporative cooling system. This is true of peak human occupancy heat load conditions when an abnormally large amount of heat is released in space It. Such conditions exist occasionally in most air conditioned spaces.

When rotaryblade I23 is in position D, and switch 9 3 and contacts I65 and I63 are maintained in their actuated positions by time clock 35 and its associated coil 97, conductors IEl'I and I68 are connected and contactor coil TI is energized starting conditioner motor I5. When conditioner motor I5 is in operation, actuating coil 5 5 is connected across leads 63 and 6| through conductor I66, contact I2, conductor I I3, thermal overload contact 93 and conductor I68. Contact I51 will therefore be actuated and will connect conductors I53 and I59. Solenoid coil I36 will then be connected across leads 63 and GI through conductors I60 and 39, contact I36, conductor I66, switch blade I2I, conductor I22, switch blad I23, conductors I63 and IE9, contact I51, and conductors I58 and I6I. Actuating coil I35 of damper position relay I32 will be energized simultaneously with the energization of solenoid coil I36 and dampers 39 and 31 will move to,ior remain in, the positions suitable for operation of the refrigerating system, as shown in Figure 1.

The energization of solenoid coil I36 opens solenoid valve 3| allowing the refrigerant gas to enter cooling coil I1 and the pressure of the refrigerant gas in cooling coil I'I will therefore be raised. Contact I46 of low pressure relay 33 will therefore be actuated and condenser motor 28 and compressor motor 26 will begin to operate. All controls other than low pressure switch 33 and high pressure switch I50 are by-passed by moving rotary switch blade I23 of the selector switch 65 to position D. Condenser motor 26 and compressor motor 26 will therefore be stopped only if the pressure of the refrigerating gas in coolingcoil H or in evaporative condenser coil 2I exceed predetermined values. The refrigerating system of the air conditioning apparatus will therefore function until either time clock 95 opens contact 96, switch 94 is opened, or the ratary switch blade I23 of selector switch'I45 is moved from position D.

Evaporatioe cooling operation only The eficiency of the refrigerating system may be seriously impaired at times by abnormal wind conditions which cause the warm and humid air discharged to the outdoors by duct 26 to be returned to the condenser coil air duct 22and bythe mechanical failure of components of the refrigerating system. Slipping of the belts which link motor 26 to blower 2i and water pump 23, low water supply in water pan 29, clogging of the filter screen usually provided in the intake of the water pump 23, clogging of the outlet apertures of spray pipe 24, and corrosion of condenser coil 2| are examples of mechanical failures which lower the elficiency of the refrigerating system. Until the wind conditions change or the malfunctioningcomponents of the refrigerating system are repaired it will be necessary to employ only the evaporative 0O01il'lg system of the air conditioning apparatus. By moving rotary switch blade I23 of selector switch to position C, only the evaporative cooling system will be allowed to operate.

With rotary switch blade I 23 in positionC and switch 9 3 as well as contacts I65 and I66 in closed position, actuator coil II is connected across leads 6i and 63 and conditioner motor I5 is caused to operate. At the same time, actuatingcoiltfl is connected across leads 6i and 63 through thermal overload contact 84, conductor MILswitch blade I38 of relay I31, conductorsIGI, I43, I62, I68, contact I66, and conductors ligand I66. Condenser motor 23 will therefore also be placed in operation. The position of damper 31 will depend on the outdoor temperature asdetermined by thermostat 43a and on the temperature of the water in pan 29 as detected by thermostat 45a. The position of damper 3? will be determined in the same manner as it is determined when the rotary switch blade I23 is in position A and only the conditioner motor I5 is operated. Whenthe outdoor temperature is below 75 degrees, conductors H6 and Ill are connected by contact I.I8 of thermostat Ma, and damper 31 moves to or remains in the position shown in Figure 1 to per- .mit a minimum of fresh air and a maximum of recirculated air to be brought into space II). When the outdoor temperature is 75-degrees or higher, contact IIB connects conductors Ill and i216 and conductors I I6 and I H will be connected only when contact I33 of thermostat 45a is actuated. Contact I33 willclose only when. the tem-.-

I seam-eaten, water in p'an' 2'9 'exceeds l 79 degrees. Wlien this 'eonditioii occurs when the outdoor temperature is '7 5 degrees or higher, dampers 31 a'nd 39 are moved' to theiposition shown in Figure l-since contactl33 will 'move to closed position short circuiting conductors I21 and I 30 and conductors I I6- and I I1. If the temperature of theoutdoor airis less than 75 degrees only damper 39 will move to theposition-shown in Figtire *1. The-normalposition ofdamper 39 duri'n'gth'dtim'e rotary switch'blade I26 is in position D'i-s that'indicated by the da'shed'line 4| of Figure 1. 'Condenser'blower'fl will therefore move freshair into space' I unless the temperature of -thewater' in pan 29 exceeds- '79 degrees.

It will be' notedthatwhen rotary switch blades I 23 is in either position A or C, solenoid coil I36 cannot be energized. l-Io'wever, a certain amount of refrigerant gas will seep through the valves of compress'or I9 and through the solenoid valve 31 -into cooling coil I1. Moreover, some refrigerant gas which is dissolved in the oil always present to greater or lesser extent in cooling coil I1 will vaporize when the temperature of the cooling coil 'I1 rises. The refrigerant gas will tend to collect in thecompressor as the pressure in-cooling'coil -I'I i'ncreases and will cause mal- "function ofcompressor I9. 'In orderto avoid such malfunction, compressor motor 20 and condenser motor 2-8will'be -allowed to operate-each time the pressure in cooling -coil I1 exceeds a predetermined valueand contact I46-of the'low pressure switch 33 is actuated. Since solenoid valve 3| will-remain closed, the c'ompressor motor 29 will operate only-the 'very short time needed to pump "the refrigerant 'gaswhich-has seeped into cooling 'c'oilI1intocondenser (30112 I. Conditioner motor I5 will' operate continuously when rotary switch blade I23 is in position A orC so that the actuator-001188 of starting conductor 66 of ccmpressor motor "20 will be connected across leads '6I and-63'each time contact I46 is moved to actuated position through conductor I 48, thermal overloadcontact 93, conductor I4I, contacts BI, I50and I46, conductors I41 and H3, contact 12 and conductor I80. In this manner the pressure -of the refrigerant gasin coil I1 is-kept below a certain'predetermined value regardless of the position of rotary-switch blade I23 but the time 0f operation of compressor I9 is kept veryshort when -blade I23 is in positions A or C in order to minimize as much as possible the periods of costlyopera'tionof compressor I9.

Automatic operation conditioner blower I4 will operate if the outdoor 'dry bulb temperature is below 75 degrees and the temperature of the air in space I0 is below 75 degrees.

If we assume now that the outdoor temperature isbelow 7-5 degrees as determined by thermostat 441; ead the indoor temperature is below -75 degrees, contact I63 of room thermostat -32 is 'in'itsopen position and contact H8 ofthermostat 44a connects conductors H6 and H1 so that damper 31 is moved to the position shown in Figure 1 closing off air duct 35a and opening air duct 36 to allow a maximum of air to berecir'culated into space I0 and to allow only a minimumof fresh'air to be moved into space I0through air duct 35. At this time only conditioner motor I5 will be' operating. If the dry bulb outdoor temperature remains below '75 degrees' and the temperature in space I0 rises above '75 degrees, contact I63 of room thermostat 32 will move to its closed position connecting actuating coil across leads 6| and 63 through'the'rmal overload contact 84, conductor I40, switch blade I 38 of switch I31, conductor I4I, contact I64 of *wet bulb thermostat 44, conductor I65, contact I66 of dry bulb thermostat 43, conductors I61 and I68, contact I63, conductor I69, switch blade I23, conductor I22, switch blade I2I, conductor I 08, contact I06, and conductors 99 and I 00, Condenser motor 28 and condenser blower 21 will therefore operate moving air cooled by the water sprayed by spray pipe 24 into space I0. Damper 39 will be in the position shown bydashed line 4| of Figure 1 since both-contacts I3I and I33 will-be in their open positions. When the temperature in space I0 falls below 75 degrees contact I63 will move into itsopen position'and condenser motor 28 will stop operating.

-If the outdoor dry bulb temperature now rises above 75 degrees, but does not exceed degrees and the wet bulb temperature is below 79 degrees, contacts I64 and I66 will maintain their positions but contact II8 will move to connect conductor II1 to I26 and cause damper motor 38 to move damper 31 to the dashed'line position 46'of Figure 1 since conductors H6 and H1 will no longer be short circuited, both contact I3I and contact I33 being open since solenoid coil I36 is not energized and the water in pan 29 has a temperature lower than '79 degrees. If the temperature in space I0- exceeds 75 degrees but does not exceed 85 degrees, "the condenser motor '28'and condenser blower '21 will blow air cooled 'by the water sprayed by pipe 24 into space I0 since damper 39 will be in the position indicated by dashed line 4|. Both blowers I4 and 21 will now be moving fresh air from the outdoors into space I0 insuring a relatively great and continuous change of air in space I0. If the temperature in space I0 should fall to '75 degrees, contact I63 will open and condenser motor 28 and condenser blower 21 will cease operating. The evaporative cooling system 'will therefore never permit the temperature in space I0 to fall below '75 degrees as long as the outdoor temperature is 75 degrees or above.

When the outdoor dry bulb temperature exceeds 85 deg'rees'and the temperature in space I0 exceeds 75 degrees contact I66, will connect conductor I61 to conductor I10 at the same time breaking the connection of conductors I65 and I61. Solenoid coil I36 will now be connected across leads 63 and 6I through conductors I00 and 99, contact I06, conductor I08, switch blade I2I, conductor I22, rotary switch blade I23, conductor I69, contact I63, conductors I68 and I61, contact I66, conductors I10 and I59, contact I51, and conductors I58 and I6I. At the same time actuating 'coil I35 of damper position relay I32 is energized short circ'uiting conductors I21 and 'andcausingdafiipers -31 and '39 to move to aessa'so 17' the positions shown in Figure 1. Damper3'l will allow a minimum of fresh air to enter space It and damper 39 will cause all air moved by condenser blower 21 to be blown outdoors. As soon as damper 39 has terminated its movement condenser motor '28 and compressor motor 29 will begin to operate provided that contact I46 of low pressure switch 33 is in its actuated position. Contact I46 will be in this actuated position whenever solenoid coil I36 is energized since the pressure in cooling coil I1 will rise due to admission of refrigerant gas by solenoid valve 3|. When the temperature in space In falls below '75 degrees, contact I63 will move to its open position and solenoid coil I36 will be de-.

energized. Solenoid valve 3| therefore closes and contact I3I of damper position relay I32 moves to its open position. Dampers 31 and 39 do not move, however, since the water in pan 29 has been raised in temperature to more than 79 degrees by the heat absorbed from condenser coil ZI and contact I33 of thermostat 45a will connect conductors I21 and I30. The temperature of the water will normally remain above .79 degrees during the operation of the refrigerating circuit. Should an abnormal condition arise and allow the temperature of the water to fall below 79 degrees, dampers 31 and 39 will move to positions 46 and AI, respectively.

Upon the next energization of solenoid coil I36, the dampers 31 and 39 will revert to their original positions. When solenoid coil I36 is deenergized, condenser motor 28 and compressor motor will continue to operate until the pressure in cooling coil I1 has been brought down by compressor I9 and contact I of low pressure switch 33 moves to openposition. When contact I46 moves to open position motors 28 and 2!] stop and remain inoperative until solenoid coil I36 is again energized and contact I46 moves to closed position.

The refrigerating system will operate even when the outdoor dry bulb temperature is below 85 degrees and contact I I6 does not connectconductors I61 and I10 if the wet bulb temperature of the outdoor air is above '79 degrees. In this case, conductor I16 is connected to conductor I51 through contact I64 which move to the right when the wet bulb temperature rises above '19 degrees, conductor I65 and contact I66 of thermostat 53 which is in its leftmost position since the dry bulb temperature is below 85 degrees. Solenoid coil I36 will, therefore, be energized if contact I63 of the room thermostat 32 is in its closed position and the refrigerating system will be in operation even though the dry bulb outdoor temperature is below 85 degrees. When the out door dry bulb temperature is 85 degrees or higher, the wet bulb thermostat 44 does not exert any control over the energization of solenoid coil 236 since conductors I61 and I10 are directly connected by contact I66 of thermostat 43.

If the refrigerating system is in operation and the dry bulb outdoor temperature drops below 85 degrees while the wet bulb temperature is below '19 degrees and the temperaturein spaced II] is above '15 degrees, contact I66 breaks the connection between conductors I61 and I16 and solenoid coil I36 and actuating coil I35 of damper position relay I32 are deenergized. Compressor motor 26 will continue in operation until contact M6 of low pressure switch 33 moves to its open position and deenergizes actuator coil 69 and actuating coil I53 of circuit breaker I42.-

18 Compressor motor 26 will stop but condenser motor 28 will remain unchanged even though contact I3I of damper position switch I32 will be open because contact I33 of thermostat 45a will remain closed since the temperature of the water in pan 29 will be above '79 degrees. Condenser motor 23 and condenser blower 21 will therefore continue to move air past condenser coil 2I and to the outdoors until the temperature of the water drops to 79 degrees or below. This insures that the air which moves past condenser coil 2i is expelled to the outdoors until the temperature of the condenser coil ill and of the water ceases to heat or humidify the air brought in from the outdoors. When the temperature of the water drops to 79 degrees or lower, due mainly to the evaporative cooling of the water sprayed by pipe 24 and movement of air caused by blower 21, contact I33 will move to open position and dampers 31 and 39 will move to dotted line positions A6 and ii, respectively to allow a maximum of fresh air to be brought into space it. When damper 39 begins to move it actuates switch I31 and will cause condenser motor 29 to cease operation until damper 39 reaches the position indicated by dashed line il. It will be understood that this interruption of operation of condenser motor.

28 will occur each time damper 39 moves from one position to the other.

The time lag between cessation of operation of the refrigeration system and the commencement of operation of the evaporative cooling circuit allows the changeover to take place without an abrupt change in temperature within space It. During the period of operation of the refrigerating system the temperature of the air within space It is maintained at '15 degrees. The outdoor temperature now falling slightly below degrees, the outdoor air which will be moved into space it by blower It will have a temperature of about 85 degrees which will cause a temperature change of aboutlO degrees, During the 10 to 20 minutes required for the changeover from operation of the refrigeration system to operation of the evaporative cooling system, the conditioner blower It will continue to recirculate air and to introduce a certain amount of outdoor air having a temperature of about 85 degrees into space I9. While the refrigerant gas in cooling coil I1 will lower the temperature of this air while the compressor I6 is operating even though solenoid valve 3! is closed, the drop in temperature willdecrease with the passage of {time from the closing of solenoid valve 3!. When dampers 31 and 39 finally change their positions to allow maximum amounts of fresh air to be brought infrom the outdoors, the temperature differential between the outdoor air and the air in space 16 will be relatively small. In addition, the temperature of the water now having fallen to '19 degrees, the temperature of the air moved by blower 21 islowered by evaporative cooling decreasing'the temperature differential still further. iChe change in temperature in space It will therefore be relatively gradual and the increased circulation of air in space id due to the additional air now moved into space It by blower 21 willmaintain the temperature and humidity conditions in space 56 comfortable to the human occupants.

Actuating winding I54 is energized when contactor coil 1! is energized and remains energized as long as conditioner motor 55 is in opera tion except when thermal overload contact 93 of compressor motor 20 is opened due to some malfunction of the refrigerating system. In the latter event, contact I51 disconnects conductor I58 fromconductor I59 and solenoid coil I35 will not be energized until contact 93 is again moved to closed position. When contact I51 is in its non-actuated position, it connects conductors I59 and I62 and insures that the evaporative cooling system will function if rotary.

switch blade I23 is in either position B, C, or D. Since compressor I9 is no longer operating, low pressure switch I46 will ordinarily close and connect actuator coil 80 across leads 6| and 63 through contact 84, conductor I49, switch blade I38, conductors I4I, I43, I62, and I44, contacts I45, I46, conductors I41 and H3, contact 12 and conductors I90 and IIII. Dampers 31 and 39 will remain in their positions until the temperature of the water in pan 29 drops below 19 degrees when contact I33 will move to its open position and dampers 31 and 39 will move to positions46 and 4|, respectively to allow a maximum of fresh air to be moved into space I0. Contact I3I will be open whenever solenoid coil I35 is deenergized and will therefore not prevent this movement of dampers 31 and 39.

In many installations the air conditioning apparatus will be subjected to a peak human occupancy heat load at night when the outdoor temperature and humidity conditions call for operation of the evaporative cooling system. In these installations a time clock I1I may be employed to maintain a contact I12 in closed position throughout the peak load period. When the contact I12 is in closed position an actuating.

and 63 coil I13 is connected across leads 6| through conductor I03, contact I12, and conductors I13a, I14, 99 and I08. Coil I13 closes a-con tact I which connects conductors I61 and [.10 to bypass or shunt thermostat 43 when rotary switch blade I23 is in position B. Solenoid coil I36 is connected across leads BI and 63 through conductors I6I and I58, contacts I51 and I15, conductors I15 and I68, contact I53 when the temperature in space I9 is above '75 degrees, conductor I69, switch blade I23, conductor I-22, switch blade I2 I, conductor I08, contact I06, and conductors 99 and I09. Since solenoid coil I35 will be energized whenever contact I63 moves to closed position, the refrigerating system will be in operation regardless of the outdoor temperature. Time clock I1I may be connected across leads 6| and 64 through conductors I03 and I11.

In the above description, the varying thermostats were described as operating when certain specific temperatures of air or water obtained. It will be obvious that these thermostats maybe set to operate when predetermined values of temperature of the air or water are reached. The optimum temperature values at which the thermostats should be set may be obtained empirically for each installation of the air conditioning apparatus.

An important advantage of my new and improved air conditioning apparatus is its 'versatility of operation which permits use of different components of the apparatus to meet the demands placed on the apparatus by variations in both internal and external conditions. The selector switch 45 allows operation of conditioner blower I4 by itself, the independent operation of either the refrigerating system or the evaporative cooling system, and theautomatic operation of either the refrigerating system or the evaporativecooling system as the external and internal conditions reach or fail to reach predetermined con ditions of temperature and humidity. V

Another important advantage of the airconditioning apparatus is its economy of operation which restricts the relatively costly operation of the refrigerating systems to the periods when only refrigerative cooling will insure comfortable conditions of temperature and humidity and which employs the relatively inexpensive evaporative cooling system at all times when evaporative cooling of the air will provide comfortable temperature and humidity conditions in space I 9.

A further advantage of my air conditioning apparatus is that it provides a cooling system for use when the refrigerating system becomesinoperative due to mechanical failures. If the condenser motor 28 and water pump 23 are in operative condition, the evaporative cooling system may be employed during the period when the refrigerating system is being restored to operative condition so that some cooling of the air in space It can always be provided.

Figure 4 illustrates a modified form of the air conditioning apparatus. For clarity of explanation, the components. of the apparatus illustrated in Figures 1 and 4 have been given like reference numerals. In the modified form of the air conditioning apparatus illustrated in Figure 4.2.11 of the air moved by the conditioner blower I 4'is drawn from the conditioned space I 0 through the duct 36, the ducts 35 and 35a and the dampers 31 and i31a. of the apparatus ofFigure 1 not being provided. In such installation, the fresh air needed for mixing with the recirculated air from the air conditioned space is drawn through the door 200 or the window 21H, of the space III. The damper 39 is shown provided with a handle 292 for manual operation although a damper motor can be provided as in the previously described embodiment. The electrical circuit diagram has not been'illustrated since any'circuit which will provide for selectively operating both the condenser blower 21 and the conditioner blower I4 when the refrigerating apparatus is kept inoperative is satisfactory. Manual switches may be used instead of the automatic temperature controlled switches previously described.

In operation, when the outdoor air temperature exceeds a certainv predetermined temperature, the refrigerating apparatus is turned on and air is moved by the conditioner blower from the conditioned space I 0 through the duct 36 over the cooling coils I1 for cooling and back into the conditioned space. Fresh air is admitted to the conditioned space through the door 200 which is usually opened periodically as people enter the conditioned space or through a window 29I which may be opened to any desired degree. During such operation, the damper39- is in the solid line position and the air driven by the condenser blower 21 after moving past the compressor I 9, compressor motor 20, condenser coil 2| is expelled through the duct 26 to the outdoors. This is the conventional operating method of refrigerating air conditioning apparatus.

When the temperature falls below a predetermined temperature, the refrigerating system is stopped by conventional controls so that no refrigerant gas is admitted into the cooling coils I1. The conditioner blower and the condenser blower are allowed to continue to operate but the damper 39 is moved to the broken line position so that the air drawn by the condenser blower from the outdoors through the window 53 is moved into the conditioned space through the duct 40 thus increasing greatly the rate of flow of air into the conditioned space. This air will be cooled by the evaporation of water sprayed by the spray pipe 24 over the condenser coils 2!.

If the temperature and humidity conditions are suitable, it may be desired merely to increase the rate of flow of fresh air into the air conditioned space without cooling any portion of the air by evaporative cooling. This may be accomplished by disconnecting the water pump 23, in either of the two embodiments of the invention, from the motor 28 by slipping off the pulley belt driving the water pump. Of course, other transmission devices may be employed if desired. For example, a clutch of any conventional type may be 'connected between the water pump and the motor 28 to facilitate the disconnection of the water pump from its driving means.

Figure illustrates still another modified form of the air conditioning apparatus. For clarity of explanation, similar components of the apparatuses illustrated in Figures 1 and 5 have been given like reference numerals. In the modified form of the air conditioning apparatus illustrated in Figure 5, the cooling coil [1, the condenser coil Zl, the conditioner blower M, the condenser blower 2i and the motors to drive these elements, and all other elements of the refrigerating apparatus are contained in the housing 330. The housing 360 has a grill in one end, not shown in Figure 1, which is similar to the grill 59 shown in Figure 1, through which air is drawn by the condenser blower 21 into the housing from the room 33! in which the housing is located. Fresh air from the outdoors can move into the room 3M through a window or grill 302 in the wall 333 of the building. U

A register 364 connecting the housing 300and the wall 335 separating the room 33! from the conditioned space H) is provided with adjustable louvers 398 which may be opened or closed to either permit or prevent air to be drawn from the conditioned space H! by the conditioner blower l4 over the cooling coil I! and back into the conditioned space It through the duct 48 which is shown provided with a plurality of registers 30'! disposed in the conditioned space I0.

The register 3% is also provided with a plurality of adjustable louvers 308 which may be opened or closed to either permit or prevent air to be drawn from the room 3M by the conditioner blower I! and back into the conditioned space I0 through the duct 48. The register 394 is old in the art and, therefore, the details of its construction are not described. Suflice it to say that the louvers 306 and 338 maybe closed or opened to any desired degree by suitable control handles on the sides of the register hidden in the drawing. In this installation, fresh air needed for mixing with the recirculated air from the air conditioned space is drawn from the outdoors through the register 302 in the wall 333 into the room 30!,

from the room 30l between the louvers 338 into,

the register 30 i, and thence into the housing 398.

In operation, when the outdoor air temperature exceeds a certain predetermined temperature, the refrigerating apparatus is turned on and air is moved by the conditioner blower from the conditioned space between the louvers 336, which are in at least partly open position, through the reg-f.

ister 33 3 over the cooling coils I! in the housing 300 for cooling and back into the conditioned space through the duct 48. Fresh air is drawn from the room 33 I, which communicate with the 22 outdoors through the register 302, between the louvers 308, which are also in at least partly open position, through the register 3% into the housing 3%, over the cooling coil I? and then into the conditioned space through the duct 48. The doorway 309 is closed, of course, by a door, not shown, during operation of the apparatus. During such operation, the damper is in the position shown and the air moved by the condenser blower 2'7 from the room 30! over the various heat producing elements of the refrigerating apparatus and the condenser coil 2! is expelled to the outdoors through the duct 26. This is the conventional operating method of refrigerating air conditioning apparatus. The outlet of duct 28 may be so positioned that none of the warm air it conducts is likely to move back into the room 3! through the register 332.

When the temperature falls below a predetermined temperature. the refrigerating system is stopped by any suitable controls so that no refrigerant gas is admitted into the cooling coil. The louvers 386 are moved into closed position so that recirculation of air from the conditioned space I0 is stopped. The conditioner blower and the condenser blower are allowed to continue to operate but the damper 39 is moved by means of the handle 39 to a position in which it closes the duct 23 and opens the duct 40, so that air drawn by the condenser blower from the outdoors through the register 332 into the housing 330 through a grill, not shown, since it is located in a side of the housing hidden in Figure 5, and through the duct 4!! into the conditioned space thus greatly increasing the rate of flow of air into the conditioned space. The air moved by the condenser blower will be cooled by the evaporation of water sprayed over the condenser coil of the refrigerating apparatus. As in the previously described forms of the invention, the water spraying of the condenser coil can be stopped by disconnecting the water pump from the motor which drives it.

While I have illustrated and described preferred embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications ma be made without departing from the spirit and scope of my invention and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What is claimed is:

1. In an air conditioning apparatus: a refrigerating system comprising a pair of heat exchangeelements, a first duct means communicating with a conditioned space, a second duct means communicating with the outdoor atmosphere, a first damper means for closing oil said first duct means, a first blower means for drawing air from said conditioned space through said first duct means and from the outdoor atmosphere through said second duct means to form a primary mixture, said first blower means moving said primary mixture over one of said heat exchange elements and into said conditioned space, said primary mixture being cooled in its passage over said one of said heat exchange elements, spray means for spraying water over the other of said heat exchange elements, a second blower means for drawing air from the outdoor atmosphere over the other of said heat exchange elements, and a third duct means communicating with the outdoor atmosphere for moving the air drawn by second blower means back to the outdoor atmosphere; an evaporative cooling system comprising said second blower means, said spray means, and a fouith duct means for moving the air drawn by said second blower means from the outdoor atmosphere and through the water sprayed by said spray means to said conditioned space; and second damper means closing oif said third duct means when in one position and closing off said fourth duct means when in a second position, said first andthird duct means being open when said refrigerating system is in operation and being closed when said evaporative cooling system is in operation, said first and second blower means operating during the operation of said evaporative cooling system and during the operation of said refrigerating system.

2. In the air conditioning apparatus of claim 1: a first motor means for operating said first damper means; a second motor means for operating said second damper means; and means responsive to the temperature and humidity conditions of the outdoor atmosphere for placing said refrigerating system in operation when predetermined values of temperature and humidity of the outdoor atmosphere are exceeded and for placing said evaporating cooling system in operation when said predetermined values are not exceeded, said last mentioned means controlling said first and second motor means to close said first and third duct means when said evaporative cooling system is placed in operation and to open said first and third duct means when said refrigerating system is placed in operation.

3. In the air conditioning apparatus of claim 2: means responsive to the temperature of the water sprayed by said spray means and associated with said second motor means for closing said fourth duct means when the temperature of said water exceeds a predetermined value.

4. In the air conditioning apparatus of claim 3: means responsive to the movement of said second damper means for stopping operation of said second blower means when said second damper means is being moved from one position to another.

5. In an air conditioning apparatus: a refrigerating system comprising a pair of heat exchange elements, a first duct means communicating with a conditioned space, a second duct means communicating with the outdoor atmosphere, a first damper means for closing off said first duct means, a first blower means for drawing air from said conditioned space through said first duct means and from the outdoor atmosphere through said second duct means'to form a primary mixture, said first blower means moving said primary mixture over one of said heat exchange elements and into said conditioned space, said primary mixture being cooled in its passage over said one'of said heat exchange elements, spray means for spraying water over the other of said heat exchange elements, a second blower means for drawing air from the outdoor atmosphere over the other of said heat exchange elements, and a third duct means communicating with the outdoor atmosphere for moving the air drawn by second blower means back to the outdoor atmosphere; an evaporative cooling system comprising said second blower means, said spray means, and a fourth duct means for moving'the air drawn by said second blower means through the water sprayed by said. spray means to saidcon'ditioned space; second damper. means associated with said third and 24' fourth duct means, said second damper means: closing off said third duct means when in one position and closing 01? said fourth duct means when in a second position, said first and third duct means being open when said refrigerating system is in operation and being closed when said evaporative cooling system is in operation, said first blower means operating during the operation of said evaporative cooling system and during the operation of said refrigerating system; a first motor means for operating said first damper means, a second motor means for operating said second damper means, and means responsive to the temperature and humidity conditions of the outdoor atmosphere for placing said refrigerating system in operation when predetermined values of temperature and humidity of the outdoor atmosphere are exceeded and for placing said evaporating cooling system in operation when said predetermined values are not exceeded, said last mentioned means controlling said first and second motor means to close s'aid first and third duct means when said evaporative cooling system is placed in operation and to open said first and third duct" means when said refrigerating system is placed in operation; and means responsive to the move ment of said second damper means for stopping operation of said second blower means when said damper means is being moved from one position to another.

6. In an air conditioning apparatus, a refrigcrating system comprising a pair of heat ex change elements, a first duct means communicating with a conditioned space, a second duct means communicating with the outdoor atmosphere, a first damper means for closing off said first duct means, a first blower means for drawing air from said conditioned space through said first duct means and from the outdoor atmosphere through said second duct means to form a primary mixture, said first blower means moving said primary mixture over one of said heat ex change elements and into said conditioned space, said primary mixture being cooled in its passage over said one of said heat exchange elements, spray means for spraying water over the other of said heat exchange elements, a second blower means for drawing air from the outdoor atmosphere over the other of said heat exchange elements, and a third duct means communicating with the outdoor atmosphere for moving the air drawn by second blower means back to the out door atmosphere; an evaporative cooling system comprising said second blower means, said spray means, and a fourth duct means for moving the air drawn by said second blower means through the water sprayed by said spray means to said conditioned space; second damper means associated with said third and fourth duct means, said second damper means closing off said third duct means when in one position and closing off said fourth duct means when in a second position, said first and third duct means being open when said refrigerating system is in operation and being closed when said evaporative cooling system is in operation, said first blower means operating during the operation of said evaporative cooling system and during the operation of said refrigerating. system; a first motor means for operating said first damper means; a second motor means for operating said second damper means; and means responsive to the temperature and humidity conditions of the out-- doorzatmospherefor placing said refrigerating.

system in operation when predetermined values of temperature and humidity of the outdoor atmosphere are exceeded and for placing said evaporating cooling system in operation when said predetermined values are not exceeded, said last mentioned means controlling said first and second motor means to close said first and third duct means when said evaporative cooling system is placed in operation and to open said first and third duct means when said refrigerating system is placed in operation; and means responsive to the temperature of the outdoor atmosphere and associated with said first motor means to move said first damper means to open said first duct means when the temperature of the outdoor atmosphere falls below a predetermined low value and to move said first damper means to close said first duct means when the temperature of the outdoor atmosphere rises above said predetermined low value temperature.

7. The air conditioning apparatus of claim 6: and means responsive to the temperature of the air within said conditioned space for arresting operation of said second blower means when the temperature of the air within said conditioned space falls below a predetermined low value and for starting operation of said second blower means when the temperature of the air within said conditioned space rises above said predetermined low value.

8. The air conditioning apparatus of claim 1: and manually operated switch means operatively associated with said refrigerating and evaporative cooling systems for permitting selective choice of operation of either of said systems.

9. The air conditioning apparatus of claim 1: and automatic control means operatively associated with said refrigerating and evaporative cooling systems and responsive to predetermined temperature and humidity conditions of the outdoor atmosphere for selectively operating either of said systems. i

10. The air conditioning apparatus of claim 9: and manually operated switch means operatively associated with said refrigerating and evaporative cooling systems and said automatic control means for permitting automatic and manually selective choice of operation of either of said systems.

11. In an air conditioning apparatus: a refrigerating system comprising a cooling 'coil a condenser coil, compressor means connected between said coils for exhausing a refrigerant gas from said cooling coil into said condenser coil. valve means between said condenser coil and said cooling coil for controlling the flow of said refrigerant gas from said condenser coil to said cooling coil, a first duct means communicating with a conditioned space, a second duct means communicating with the outdoor atmosphere, a first damper means having two operative positions associated with said first and second duct means, said first damper means closing off said first duct means when in one of said two operative positions and opening said first duct means when in the other of said two operative positions, a first blower means for moving air past said cooling coil, said first blower means circulating air from said conditioned space and from said outdoor atmosphere over said cooling coil and into said conditioned space when said first damper is in one of said two operative positions, said first blower means circulating air only from the outdoor atmosphere over said cooling coil and into said conditioned space when said first damper means is in the other of said two operative conditions, said air being cooled in passing over said cooling coil when said valve means permits refrigerant gas to move from said condenser coil to said cooling coil, means for spraying water over said condenser coil, a second blower means for drawing air from the outdoor atmosphere over said condenser coil, and a third air duct means communicating with the outdoor atmosphere for moving air drawn from the outside atmosphere by said second blower means back to said outdoor atmosphere; an evaporative cooling system comprising said second blower means, said water spray means, and a fourth air duct means communicating with said conditioned space for moving air moved by said second blower means through the water sprayed over said condenser coil into said conditioned space; and a second damper means having two operative positions operatively associated with said third and fourth duct means, said second damper means closing said third duct means when in one of said two operative positions and closing said fourth duct means when in the other of said two operative conditions, said first damper means being in said other of its two operative positions and said second damper means being in said one of its two operative positions when said refrigerating system is in operation, said first damper means being in said one of its two operative positions and said second damper means being in said other of its two operative positions when said evaporative cooling system is in operation.

12. In the air conditioning apparatus of claim 11: a first motor means for operating said first damper means, a second motor means for operating said second damper means; and means responsive to predetermined conditions of temperature and humidity of the outdoor atmosphere for maintaining said refrigerating system in operation when the temperature and humidity of the outdoor atmosphere exceed predetermined values and for maintaining said evaporative cooling system in operation when the temperature and humidity of the outdoor air do not exceed said predetermined values, said last mentioned means controlling said first and second motor means to close said first and third duct means and open said fourth duct means when said evaporative cooling system is in operation and to open said first and third duct means and close said fourth duct means when said refrigerating system is in operation.

13. In the air conditioning apparatus of claim 12: means responsive to the temperature of the water sprayed by said spray means and operatively associated with said second motor means for closing said fourth duct means when the temperature of said water exceeds a predetermined value.

14. In the air conditioning apparatus of claim 13: means responsive to the movement of said second damper means for stopping operation of said second blower means when said second damper means is being moved by said second motor means from one of its two operative positions to the other.

15. In the air conditioning apparatus of claim 14: means operatively associated with said compressor and said first and second motor means for placing said evaporative cooling system in operation when said compressor fails to function when the temperature and humidity of the outdoor temperature exceeds said predetermined values.

16. In an air conditioning apparatus: a refrigerating system comprising a cooling coil, a condenser coil, compressor means connected between said coils for exhausing a refrigerant gas from said cooling coil into said condenser coil, valve means between said condenser coil and said cooling coil for controlling the flow of said refrigerant gas from said condenser coil to said cooling coil, a first duct means communicating with a conditioned space, a second duct means communicating with the outdoor atmosphere, a first damper means having two operative positions associated with said first and second duct means, said first damper means closing off's'aid first duct means when in one of said two operative positions and opening said first duct means when in the other of said two operative positions, a first blower means for moving air past said cooling coil, said first blower means circulating air from said conditioned space and from said outdoor atmosphere over said'cooling coil and into said conditioned space when said first damper means is in said one of said two operative positions, said first blower means circulating air only from the outdoor atmosphere over said cooling coil and into said conditioned space when said first damper means is in the other of said two operative conditions, said air being cooled in passing over said cooling coil when said valve means permits refrigerant gas to move from said condenser coil to said cooling coil, means for spraying water over said condenser coil, a second blower means for drawing air from the outdoor atmosphere over said condenser coil, and a third air duct means communicating with the outdoor atmosphere for moving air drawn'from the outside atmosphere by said second blower means back to said outdoor atmosphere; an evaporative cooling system comprising said second blower means, said water spray means, and a fourth air duct means communicating with said conditioned space for moving air drawn by said second blower means into said conditioned space; and a second damper means having two operative positions operatively associated with said third and fourth duct means, said second damper means closing said third duct means when in one of said two operative positions and closing said fourth duct means when in the other of said two operative conditions, 'said'first damper means being in said other of its two operative positions and said second damper means being in said one of its two operative positions when said evaporative cooling system is in operation, said first damper means being in said one of its two operative positions, said second damper means being in said other of its two operative positions when said refrigerating system is in operation, a first motor means for operating said first damper means, a second motor means for operating said second damper means; and means responsive to predetermined conditions of temperature and humidity of the outdoor atmosphere for main-- taining said refrigerating system in operation when the temperature and humidity of the outdoor temperature exceed predetermined values and for maintaining said evaporative cooling system in operation when the temperature and humidity of the outdoor air do not exceed said predetermined values, said last mentioned means controlling said first and second motor means to close said first and third duct means and open said fourth duct means when said evaporative cooling system is in operation and to open said first and third duct means and close said fourth duct means when said refrigerating system is 28 operation; and means responsive to the move ment of said second damper means for stopping operation of said second blower means when said second damper means is being moved by said second motor means from one of its two operative positions to the other.

17. In an air conditioning apparatus: a refrigerating system comprising a cooling coil, a condenser coil, a compressor means connected between said coils for exhausting a refrigerant gas from said cooling coil into said condenser coil, valve means between said condenser coil and said cooling coil for controlling the fiow of said refrigerant gas from said condenser coil to said cooling coil, a first duct means communicating with a conditioned space, a second duct means communicating with the outdoor atmosphere, a first damper means having two operative positions associated with said first and second duct means, said first damper means closing ofi said first duct means when in one of said two operative positions and opening said first duct means when in the other of said two operative positions, a first blower means for moving air past said cooling coil, said first blower means circulating air from said conditioned and from said outdoor atmosphere over said cooling coil and into said conditioned space when said first damper means is in said other of said two operative positions, said first blower means circulating air only from the outdoor atmosphere over said cooling coil and into said conditioned space when said first damper means is in said one of said two opera tive conditions, said air being cooled in passing over said cooling coil when said valve means permits refrigerant gas to move from said condenser coil to said cooling coil, means for spraying water over said condenser coil, a second blower means for drawing air from the outdoor atmosphere over said condenser coil, and a third air duct means communicating with the outdoor atmosphere for moving air drawn from the outside atmosphere by said second blower means back to said outdoor atmosphere; an evaporative cooling system comprising said second blower means, said water'pump means, and a fourth air duct means communicating with said conditioned space for moving air drawn by said second blower means into said conditioned space; a second damper means having two operative positions operatively associated with said third and fourth duct means, said second damper means closing said third duct means when in one of said two operative positions and closing said fourth duct means when in the other of said two operative positions, said first damper means being in said other of its two operative positions and said second damper means being in said one of its two operative positions when said evaporative cooling system is in operation, said first damper means being in said one of its two operative positions and said second damper means being in said other of its two operative positions when said refrigerating system is in operation; a first motor means for operating said first damper means; a second motor means for operating said second damper means; and means responsive to predetermined conditions of temperature and humidity of the outdoor atmosphere for maintaining said refrigerating system in operation when the temperature and humidity of the outdoor atmosphere exceeds predetermined values and for maintaining said evaporative cooling system in operation when the temperature and humidity of the outdoor air do not exceed'said predetermined values, said last mentioned means controlling said first and second motor means to close said first and third duct means and open said fourth duct means when said ev-aporative cooling system is in opera-- tion and to open said first and third duct means and close said fourth duct means when said refrigerating system is in operation; and means operatively associated with said first motor means responsive to the temperature of the outdoor air and operative when said evaporative cooling system is in operation to move said first damper means to open said first duct means when the temperature of the outdoor atmosphere falls below a predetermined low value and to close said first duct means when the temperature of the outdoor atmosphere rises above said predetermined low value.

18. The air conditioning apparatus of claim 1'7: and means responsive to the temperature of the air within said conditioned space and operative when said evaporative cooling system is in operation for arresting operation of said second blower means when the temperature of the air within said conditioned space falls below a predetermined low value and for starting operation of said second blower means when the temperature of the air within said conditioned space falls below a predetermined low value and for starting operation of said second blower means when the temperature of the air within said conditioned space rises above said last mentioned predetermined low value.

19. The air conditioning apparatus of claim 11: and manually operated switch means operatively associated with said refrigerating and evaporative cooling systems for permitting selective choice of operation of either of said systems.

20. The air conditioning apparatus of claim ll: and automatic control means operatively associated with said refrigerating and evaporative cooling system and responsive to predetermined temperature and humidity conditions of the outdoor atmosphere for selectively operating either of said systems.

21. The air conditioning apparatus of claim 9:

and manually operated switch means operatively associated with said refrigerating and evaporative cooling system and said automatic control means for permitting automatic and manually selective choice of operation of either of said systems.

22. In the air conditioning apparatus of claim 11: and pressure responsive switch means connected between said cooling coil and said compressor and operatively associated with said compressor for maintaining said compressor in operation when the pressure of said refrigerant in said cooling coil exceeds a predetermined value.

23. In an air conditioning apparatus: a refrigerating system comprising a pair of heat exchange units, a first blower means for moving air over one of said heat exchange units and into a conditioned space, said air being cooled in moving over said one of said heat exchange units, a cooling means for removing heat from the other of said heat exchange units comprising a second blower means and a water spray means, said water spray means forming a water spray over said other of said exchange units, said second blower means moving air from the outdoor atmosphere over said other of said heat exchange units and back to the outdoor atmosphere; and an evaporative cooling system comprising said spray means, said second blower, and means for directing the air moved by said second blower 30 means from the outdoor atmosphere through said water spray to said conditioned space when said evaporative cooling system is in operation, said first blower means being in operation during the operation of said refrigerating system and said evaporative cooling system.

. .24. The air conditioning apparatus of claim 23: and manually operable means for selectively placing either of said systems in operation.

25. The air conditioning apparatus of claim 23: and automatic control means responsive to predetermined values of temperature and humidity of the outdoor air for selective operation of either of said systems.

.26. In an air conditioning apparatus: a refrigerating system comprising a pair of heat exchange units, a first blower means for moving air from a conditioned space and from the outdoor atmosphere over one of said heat exchange units and into said conditioned space, said air being cooled in moving over said one of said heat exchange units, a cooling means for removing heat from the other of said heat exchange units comprising a second blower means and a water spray means, said water spray means forming a water spray over said other of said heat exchange units, said second blower moving air from the outdoor atmosphere over said other of said heat exchange units and back to the outdoor atmosphere; and an evaporative cooling system comprising said spray means, said second blower, and means for directing the air moved by said second blower from the outdoor atmosphere through said water spray to said conditioned space when said evaporative cooling system is in operation; and means operatively associated with said first blower for allowing said first blower to move air from the prising a second blower for moving air from the outdoor atmosphere over said other of said heat exchange units and back to the outdoor atmosphere; and means for increasing the volume of air moved from the outdoor atmosphere into said conditioned space when said refrigerating system is not in operation, said last mentioned means including said second blower and means for directing the air moved by said second blower from the outdoor atmosphere into said conditioned space.

28. In an air conditioning apparatus: a refrigerating system comprising a pair of heat exchange units, a first blower means for moving air from a conditioned space and from the outdoor atmosphere over one of said heat exchange units and into said conditioned space, said air being cooled in moving over said one of said heat exchange units, a cooling means for removing heat from the other of said heat exchange units comprising a second blower for moving air from the outdoor atmosphere over said other of said heat exchange units and back to the outdoor atmosphere; and means for increasing the volume of air moved from the outdoor atmosphere into said conditioned space when said refrigerating system is not in operation, said last mentioned