US2204394A

US2204394A - Air conditioning system

Info

Publication number: US2204394A
Application number: US70100A
Authority: US
Inventors: Edward A Bailey
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1936-03-21
Filing date: 1936-03-21
Publication date: 1940-06-11
Anticipated expiration: 1957-06-11

Description

June 11, 1940. E. A. BAILEY 2,204,394

AIR CONDITIONING SYSTEM Filed larch 21 1956 Inventor: Edward A. Bailey 9 Attorney.

Patented June 11, 1940 v 2,204,394

UNITED STATES PATENT 1 OFFICE AIR CONDITIONING SYSTEM Edward A. Bailey, West Caldwell, N. J.', assignor to General Electric Company, a corporation of New York Application March 21, 1936, Serial No. 70,100

19 Claims. (01. 257-3) My invention relates to' air conditioning sys- It is, therefore, an object of my invention to .tems and more particularly systems adapted for divide the building into zones, some predomiboth automatic heating and cooling in year nantly affected by the sun in the morning and around service. the others in the afternoon, and to provide each 5 The principal object of my invention is to prozone with a conditioner comprising main cooling 5 vide improved means for controlling a multiple means and anauxiliary cooling means whose zone system of the above type. capacity may be shifted from one conditioner to It is also an object of my invention to prothe other to compensate for variations in the vide each zone with an individual air conditioner cooling load resulting from the variable position having heat exchange apparatus with variable of the sun. 10 heat exchange areas and time controlled means It is a further objectof my invention to profor selectively varying these-areas. vide each zone and its associated conditioner 3n the standard of conditions maintained within the More specifically, it is an bject of my v with anindependent cooling control and to protion to provide each zone with an individual air vide time-v controlled means for shifting the conditioner having oo ns ea comprising auxiliary cooling means and its associated conmain and auxiliary heat absorbing surfaces, to 01 fr m one zone to the m selectively supply the i Surfaces of each A still further object of my invention is the dmoner with refrigerant in respmlse to 179m provision of control whereby the auxiliary coolperature variations in some space in which such mg means will be placed into operation when variations are representative of the average space e temperature within a particulai. zone reaches within respective zones and to supply refrig" a predetermined value and the main cooling erant to said auxiliary surfaces at certain predemeans later if the temperature reaches a second termined periods to thereby selectively vary the predetermined and higher value so that the total eii'ective heat absorbing surface of the coolperiods of operation of the apparatus will be ing means associated with each conditioner. more nearly equal.

b found deslrable dwlde. large Another object of my invention is the provision m to be conditloned. mto of a control for the year around conditioner plural ty of zones 1n order more economically to whereby the same will selectively heat or cool condition the same and to more readily control the building. without the requirement of manual operations. so

In the past when a central duct system with branch ducts leading to the various rooms of the building has been used it has been customary to utilize a thermostat positioned within each room 85 to control the flow of conditioned medium to thatroom. When the operation of the conditioner has been changed from heating to cooling and vice versa, it hasbeen necessary manually to change the connections between the room thermostat and the means for regulating the fiow of medium in order to admit the flow of various parts of the building. Each zone may consist of a number of rooms or spaces having heat losses and gains that may be considered average and others that are different. The flow 3.", of heat exchange medium to the average rooms may be controlled by a thermostat placed at some point that is representative of the average space while the flow to the other rooms may be controlled by individual damper controlling thermoan stats in those rooms. 5

In numerous instances it happens that the building is of considerable length and placed in the north and 0uth position, or Otherwise heated medium to the room on a decrease in temcause of its plan of construction, possesses con- Denture below value and cooled 4r siderable area subject to the eflect of the'suns medium on an increasem temperature above radiation during the major t of t another value. It is an object of my invention especially during those seasons when cooling is to Obvlate this reflulrement and to Provide n most likely to be required. Calculations show improved automatlo thermostat e s n co tro that the effect of the suns radiations is considfor re u t the w of o ediu at difm erable and that the load imposed on the cooling fer nt' t mp u and having a s parate apparatus associated with a particular zone varies er os y controlled concatenated e ersover a considerable range each day as the suns 8 ea for automatically rel/{$51118 w rays strike the zone at different angles or strike spect to temperature the reversmg control of more or less of the area defining a particular the thermostat on the flow regulating means zone. for automatically reversing with respect to temperature the action of the thermostat on the flow regulating means.

It is a further object of my invention to provide an additional thermal responsive means located, similarly to the cooling control at some point the temperature of which is representative of the zone for controlling the heating means associated with each conditioner and the reversal of the room thermostat, so that when the conditioner is effective to heat the conditioning medium the action of the thermostat is reversed.

In conditioning large buildings it is necessary to meet the varying requirements of a large number of tenants. -In a system of the type under consideration it is obvious that under certain conditions the flow of air through any particular room is stopped when the damper is operated into a closed position. It is, therefore, a further object of my invention to provide means whereby any space or spaces may be supplied with continuously circulated air.

Specifically, this last mentioned object is accomplished by providing an independent duct leading to a certain room or rooms from a point intermediate the air circulating means and conditioning means of the conditioner and providing mechanically interconnected dampers in the two branch ducts leading to the room and under the control of a single thermostat located within the room. The thermostat is arranged to control the damper actuating means so that the latter will simultaneously open one duct and close the other in response to conditions within the room to maintain a continuous circulation of either conditioned or by-passed air therethrough.

The features of my invention which are believed to be new and novel will be pointed out in the claims appended hereto. For a better understanding of the invention reference is made in the following description to the accompanying drawing, partially diagrammatic, illustrating a system embodying my invention.

In the single figure I have illustrated in diagrammatical fashion a building Ill consisting of two zones II and I2, the former which, for convenience, may be considered as being the east side of the building and the latter the west side.

Zone H is accordingly affected to a considerably greater degree by the suns rays in the morning and zone l2 in the afternoon. Because of limitation of space, I have illustrated but three rooms in each zone, rooms A, B, and C in zone II and rooms D, E, and F in zone l2, but it is obvious that any number of rooms may be placed in each zone. Furthermore, it is obvious, as will appear more fully later, that my invention is not limited to systems consisting of two zones only. Any number of zones may be conditioned equally well.

Each zone is supplied with conditioned air from its associated conditioner and a central duct system. Zone II is provided with a conditioner l3 from which conditioned air is circulated to the various spaces or rooms within the zone through a central duct I4 and a plurality of branch ducts l5 leading to the respective rooms. The air is returned through branch ducts I6 to a central return duct I1 leadingback to the conditioner l3. In similar manner, zone I2 is provided with a conditioner 18, a central air duct l9, and branch ducts 20 leading to' the respective rooms within that zone. The air is likewise returned to conditioner l8 through branch ducts 2| and central return duct 22.

As stated previously certain rooms having an average heat loss and gain are provided with continual circulation of heat exchange medium and others, subject to unusual conditions, are provided with dampers controlled by thermostats placed in those rooms. Rooms C and F are of the type having average heat gain and loss and are thus illustrated as being supplied with heat exchange medium directly from the central duct and have no dampers controlling the flow thereof to the rooms.

The flow of air to other rooms subject to unusual conditions is controlled by

thermostats

25, 26, 21, and 28 in rooms A, B, D, and E, respectively. The thermostats control, in a manner to be more fully described hereinafter, individual means 29, 30, 3|, and 32, respectively, adapted to actuate flow regulating means such as dampers 33, 34, 35, and 36, respectively.

Because of the fact that certain tenants require different types of conditioning it often occurs that it is desirable to continuously circulate the conditioning medium through a space subject to unusual conditions. To obtain this result there is provided an independent duct 24 leading to room B from a point intermediate the medium circulating and conditioning means of conditioner l3. Positioned in duct 24 is a damper 31 also operated by damper actuating means 30 under the control of thermostat 2B in room B. Dampers 34 and 31 are so interlinked that when one damper is closed the other is open. By this construction continuous flow of air through room B is provided and it may be seen that such flow will consist of either conditioned air, when damper 34 is open, or unconditioned air, that is, a combination of recirculated and freshair, when damper 31 is open. The proportions of fresh air and recirculated air are controlled by a plurality of dampers indicated generally by reference numeral 38, positioned, as illustrated, in the central return ducts and in the fresh air ducts 39 and 40 associated with each conditioner.

The conditioner l3 associated with zone ll consists of air circulating means such as a motor driven fan 4| and means for heating and cooling the air. Means for humidifying the air are usually provided but they are not shown in the figure. The heating means consists of a coil 42 positioned in the path of the air flow and through which fiowsa suitable heat exchange medium, such as steam, under the control of a two position motor operated valve 43. The cooling means comprises a pair of heat absorbing surfaces consisting of a main evaporator 44 and an auxiliary evaporator 45 for cooling the air as it flows through the conditioner. Heat absorbing surface 44 is supplied with refrigerant or other cooling medium through a conduit 46 under the control of a thermostatic valve 41 to which liquid refrigerant is supplied through conduit The latter is connected to a condenser 50 which may be cooled by any desirable means, not shown. The condenser is connected to a compressor 5| adapted to compress vaporized refrigerant conducted thereto from evaporator 44 through a conduit 52. Compressor 5| is driven by any suitable means such as an electric motor 53 which receives power from a suitable source in a manner to be described later.

Conditioner l8 associated with zone I2 is likewise provided with a heating coil 56 which is supplied with steam under the control of a two position motor operated valve 51.

The condi- 48 from a liquid receiver 49. A

tioner is also provided with main and auxiliary heat absorbing surfaces such as evaporators 58 and 59. Evaporator 58 receives refrigerant through a conduit 60 under the control of a thermostatic valve 6|. A conduit 62 connects the latter to a liquid receiver 63 which is in turn connected through a condenser 64 to a compressor 65. The evaporated gaseous refrigerant is led back from evaporator 58 to the compressor through conduit 66. The compressor is driven by any suitable motive means such as an electric motor 6'! connected to a suitable source of power.

Auxiliary evaporators 45 and 59 associated with conditioners I3 and I8 respectively are selectively furnished with refrigerant, the former during the forenoon when the sun is in the east and the latter during the afternoon when the sun is in the west from a compressor 68, driven by a suitable electric motor 69, the compressed refrigerant flowing through condenser 10 and liquid. receiver II to a conduit I2. When it is desired to admit the refrigerant to evaporator 45, an electrically operated valve I3 positioned in conduit 12 permits therefrigerant to flow to the evaporator under the control of a thermostatic valve 14. The evaporated refrigerant is led back to the compressor through conduits I5. When it is desired to render evaporator 59 effective, an electrically operated valve 18 in conduit 12 is actuated to its open position to admit the flow of liquid refrigerant to evaporator 59 under the control of a thermostatic valve 11. The gaseous refrigerant is thereafter led back to the compressor through conduits 15. The operation of valves 13 and I6 is under the control of suitable timing apparatus, to be described hereinafter, permitting but. one of these valves to be in its open position at any particular time. The operation of the cooling units driven by motors 53, 61. and 69 is suitably controlled by thermal responsive means positioned in the zones at places having a heat loss and heat gain representaive of the average space in the zone.

Before describing the improved control in detail I shall. for purpose of-simplification, outline it briefly. The control of the cooling system is independent of the control of the heating system, that is, independent thermal responsive controls are provided for each system. In addition, the operation of each conditioner is controlled by thermal responsive means positioned within the zone with which the conditioner is associated. The thermal responsive means are, in the conditioning system I have illustrated, located at some point the temperature of which is representative of the temperature of the entire zone and, as stated above, rooms and F are of this nature. In addition, the auxiliary cooling apparatus is provided with a double control, one control being located in one zone and the other in the second. The control is in turn transferred from one zone to the other by suitable time control means that operates simultaneously to shift the control from one zone to another and to close the electrically operated valve in one refrigerant line and open that in the other.

For purpose of simplicity the control of the cooling system will be described first. In room C of zone II I have provided a suitable thermal responsive means such as a thermostat 8| comprising a suitable bimetallic thermal responsive element 82 with which is associated a pair of normally stationary contacts. The thermostat is so constructed that the thermal element moves to the left in response to an increase in temperature and upon engagement with its left hand contact will close an energizing circuit for an associated relay; Engagement by the thermomoves to connect conductors 83 and 84 that relay 8. is energized to establish a holding a circuit for itself through switch 93. Simultaneously therewith, switch 94 is closed to energize relay 95 by connecting the latter across supply lines 89 through conductors 96, 91, and 98. Energization of relay 95 effects closure of switch 99,

which in turn energizes motor 53 by connecting the latter to the supply line through conductors After the cooling system remains in operation for a suflicient length of time to cool the zone and decrease the ambient surrounding thermostat 8| to a point where thermal responsive element 82 makes contact with its right hand contact then a circuit is closed across conductors 84 and 85. This results in the short circuiting of relay 88 and in actuation of switches 93 and 94 'to their open positions, thus de-energizing compressor motor 53 and rendering ineffective the cooling system.

The control of conditioner I8 by a thermostat positioned at a point the temperature of which is representative of the entire zone, that is, in room F, is similar to that just described in connection with zone I I. A thermostat IOI consisting of a thermal responsive element I02 and associated stationary contacts is connected by conductors I03, I04, and I05 to a relay I06 comprising a transformer I01 and a relay winding may be started at any particular moment, thus obviating any sudden large demands on the power supply. Associated with relay winding I08 is a" switch II3 adapted to close a holding circuit for the winding when the latter is energized and a switch II4 adapted to close an energizing circuit for relay H5. The energizing circuit for the last mentioned relay is from one side of supply 89 through conductor H6, switch II4, conductor 1, relay H5 and conductor 8 to the other side of the supply. Upon energization of relay II5 its associated switch H9 is actuated into its closed position to close an energizing circuit for compressor motor 61 through conductors I20.

g It may be noted that when the thermal element I02 moves to the left into" engagement with its left hand contact upon an increase in temperature to close a circuit across conductors I03 and I04, relay winding I08 is energized .to cause operation of compressor motor 81. When the temperature within the zone and surround- .rangement shown, it is obvious that but one unit ing thermostat IOI decreases to a predetermined value then a circuit is formed across conductors I04 and I05 to short circuit relay winding I08 to effect de-energization of compressor motor 61.

I shall now discuss briefiy the details of the control of the auxiliary cooling apparatus. As stated previously, the apparatus is under the control of time controlled means so that the refrigerant is circulated to either one conditioner or the other during certain predetermined periods and also under the control of thermal responsive means within the zone to which the conditioner supplies conditioned medium. The control is supplied with energy from source 89 through conductors I2I and through time controlled switches I22 and I23 comprising telechron motors I24, permanently connected across the supply line, and mercury type switches I25 and I26. These switches are disclosed only schematically since they are well known to those skilled in the art. Control switch I22 is provided for the purpose of controlling the energization of the apparatus as an entirety. In some systems it is desirable that the system function only during certain periods of the day and switch I22 is so constructed that it will close a circuit only during the desired periods of the day; or it may be constructed in such manner that no cooling will take place on predetermined days. Obviously, the switch may be dispensed with entirely if cooling is desired at all times.

Considering first the operation of switch I22 as it effects the energization of the refrigerating apparatus already described, it will be noted that one pole of the switch is connected to one of the supply lines 89 through conductors I 2| and I21. The other pole of the switch is connected by conductor I28 to relay winding I29 which controls the operation of a switch 92 governing the operation of compressor motor 53, and switch I I I governing the operation of compressor motor 61. Conductor I26 is connected by means of conductor I30 to the middle pole of switch I26. Switch I26 is of a type that makes contact between the middle pole and the right hand pole during certain periods and between the middle pole and the left hand pole at other periods. For purpose of illustration it will be assumed that the switch is so co-ordinated with its driving means that the middle and right hand poles are connected during the forenoon and the middle and left hand poles during the afternoon. The right hand pole is connected by means of conductor I3I to the primary winding of a transformer I32 from which leads a common connection I33 to one side of the powerline. Thus, when switch I26 is in the position where the middle and right hand poles are connected, transformer I32 is energized and when the switch is in its opposite position, a circuit is formed by conductor I34 through the primary winding of transformer I35.

Associated with transformer I32 is a relay winding I36, the energization of which is controlled through conductors I31, I38, and I39, by a thermal responsive means located in room C. Conductor I31 is connected to the thermal element I40 of thermal responsive means MI and conductors I38 and I39 are connected to the right and left hand contacts thereof, respectively.- It will be seen that when the thermal element I40 moves to the left into engagement with its left hand contact in response to an increase in temperature that a circuit is closed across con -for the relay winding is closed by switch I42.

Energization of the winding also causes closure of switches I43 and I44, the former closing an energizing circuit tothe solenoid controlling the operation of valve 13 in the refrigerant circulating system. This circuit leads-from one side of the source of power through conductors I33 and I45 to switch I43, conductor I46 to relay I41 and back through conductor I48 to the other side of the source. Closure of switch I44 establishes a circuit through conductor I49 to a relay I 50 controlling the operation of a switch I5I adapted in turn to energize compressor motor-69 by connecting the latter to the source of supply through conductors I 52.

During that portion of the day that transformer I35 is energized, the auxiliary cooling means is made effective to cool air flowing through the conditioner associated with zone I2 and the control thereof is likewise transferred to a thermostat located in room F. This thermostat, indicated by reference numeral I53, has its thermal responsive element I54 and associated contacts connected through conductors I55 and I56, I51 to the secondary of transformer I35 and to relay winding I58. When the thermal element I54 moves to the left into engagement with its left hand contact in response to an increase in temperature a circuit is closed across conductors I55 and I56 to energize relay winding I 58. Energization of the relay effects closure of aholdingcircuit for the relay by means of switch I59. Simultaneously, switches I60 and I6I are closed, the former energizing through conductor I62 a solenoid I63 controlling the operation of valve 16 in the refrigerant line leading to evaporator 59. Switch I6I closes a previously described circuit through conductor I49 to energize relay I50 and to initiate operation of compressor motor 69.

Heating of the air is, as has been previously brought out, under the control of co-operating but independent thermal responsive means. Each zone is provided with a thermostat located in the rooms C and F, respectively, having average heat gains and losses controlling the admission of a heating medium to the heating coil associated with the conditioner of a particular zone. A thermostat I64 positioned in room C has its thermal element I65 and associated contacts connected by means of conductors I66, I61 and I68 to a relay comprising a transformer I69 and relay winding I10 similar to those already'described. The primary of the transformer receives energy from a suitable source 89 to which it is directly connected. The thermal element I65 is so arranged that it moves to the left in response to a decrease in temperature, and it may be noted from the drawing that when it engages its left hand'contact a circuit is closed across conductors I61 and I68 to energize relay winding I10. Energization of this winding effects closure of switches I1I, I12, and I13 and opening of switch I14. The closure of switch I1I establishes a holding circuit for relay I10 that maintains the relay energized until such time that a short circuit is formed across relay winding I10 through the connection of conductors I66 and I61 by thermal element I65 in response to an increase in temperature.

Closure of switch I12 causes a reversal in the action of thermostats 25 and 26 associated with the'dampers controlling the admission of fluid to each zone. It is evident that if a single thermostat is to be used in each room that it cannot be used for control of the same dampers both in winter and in summer unless some reversing means are provided. The reversing arrangement to be described more fully when damper actuating means 29 is described provides a simple and efficient means for reversing the connections between the room thermostats and the damper actuating means.

The opening of switch I14 and closure of I13 efiects operation of the two position motor operated valve 43 governing the admission of steam to heater coil 42. The switch I14 is connected to the motor of valve 43 by conductor I15 and switch I13 is connected thereto by conductor I16. A connection I11 from the source of supply also leads to the valve operating motor and it will be obvious to those skilled in the art thatif the motor is of the well known type having a double winding, energization of a portion of which operates it in one direction and energization of the remaining portion operates it in another direction, then thealternate breaking and making of the circuits defined by conductors I15 and I16 will result in operating the steam control valve alternately into its open and closed positions.

' The admission of steam to heater coil 56 of conditioner I8 is governed in a similar manner by a'thermostat I in room F. The thermal element I 8| and associated contacts are connected by means of conductors I82, I83, and I84 to a transformer I85 and relay winding I86. The transformer is connected directly to the source of supply 89. When the thermal element I8I moves to the left in response to a decrease in temperature it closes an energizing circuit for winding I 98' across conductors I83 and I84. Winding I86 thereupon establishes a holding circuit for itself by closure of switch I81.

The action of room thermostats 21 and 28 controlling the'dampers governing the admission of heat exchange medium to the various rooms in zone I2 is reversed by closure of switch I88. The resulting establishment of a circuit from one side of power supply 89 on the right hand side of the figure through conductor I89 to damper actuating means 3| and 32 and from thence to the other side of the power supply line 89 at the left hand side of the drawing is in a manner that will be more fully described when the damper actuatin means 29 is described in detail. Energization of relay I86 also causes closure of switch I90 and opening of switch I9I controlling circuits I92 and I93 leading to the operating means associated with valve 51 controlling the flow of steam-to heater coils 56 of conditioner I 8. The middle wire I18 of operating member 51 is connected to the middle wire of operating member 43 and from thence to the source of power through connection I11.

. The individual damper controlling thermostats 25 to 28, inclusive, and the associated damper actuating mechanisms 29 to 32, inclusive, are all alike and consequently, I have shown in detail only the one for roomA. The power is supplied from the source 89 through transformers I94 and I95 to relay winding I96 and damper operating motor I91, respectively, the transformers being connected to the power supply line by conductors I98. One terminal of winding I96 is directly connected to the thermal element of thermostat 25 through conductor I99 and the other side thereof is connected to a switch member 200 movable from engagement with a lower contact, connected to the right hand stationary contact motor I91 to open and close the damper.

of thermostat 25 through a conductor 20I into engagement with an upper contact connected to the left hand stationary contact of thermostat 25 through a conductor 202. Associated with switch 200 isa second switch 203 similarly movable from a lower contact into engagement with an upper contact. The opposite contacts associated with these two switches are interconnected in such manner that as the switches 200 and. 203 are moved upward by energization of a reversing relay 204 the action of the thermostat 25 with respect to the relay I96 is reversed.

The reversing relay 204 is under control of the thermostat I64 in room 0, the latter controlling the energization of relay winding I10 which, when energized,- effects closure of switch Closure of this switch energizes the reversing relay 204 through a conductor 2.05. As-

sociated with relay I96 is a switch 206, the clo- I sure of which establishes the holding circuit for relay I96.

Also associated with relay winding I 96 is a second switch 201 controlling the energization of Also associated with the switch are a pair of co-opcrating contacts termed, for sake of simplicity, upper and lower contacts, and a limit switch mechanism comprising a cam 208 and movable switch members 209 and 2"). Engagement of switch member 201 with its associated upper contact upon energization of relay -winding I96 completes a circuit from that contact through conductor 2I I, motor I91, secondary winding of transformer I95, conductors 2I2 and 2I3, limit switch 2I0 and conductor 2I4 to. switch member I limit switch 209, and conductor m to switch member 201, thereby energizing motor I91 to return damper 33 to its closed position. Cam 208 rotates opening limit switch 209 to deenergize motor I91 and closing limit switch 2I0 preparatory to-the next energization of relay I96.

It will be understood that other well-known forms of damper actuating means may be employed if desired. This is true particularly if modulated control of the damper is desired and if such modulated control is deemed to be desirable, the damper operating motor and control above described may be modified in the manner shown In Letters Patent 1,902,327-Hall, also assigned to the assignee of the present application.

and controls are similar in all respects to that just described. Similar connections have been labeled similarly in all cases, with the exception of the conductor leading to the reversing relay associated with the thermostats in zone I2. As

stated previously, this conductor is labeled with reference numeral I89 and leads directly. to a switch I88 that is operated by relay I86.

Before proceeding with the description of the operation of the system as a whole, it will be nec- The remaining damper actuating mechanisms essary to assign certain arbitrary values at which the various thermostats will operate. It will be assumed that the various thermostats 25 to 28, inclusive, controlling the operation of the dampers will be set to operate at in summer and 72 in winter. No automatic means for so changing the setting of these thermostats is shown and as far as the apparatus is concerned the shift may be made manually whenever desired. Thermostats I84 and I88 are set to operate at 72 during the day time and may be set to operate at 60 during the night time, provided a corresponding change is made in the setting of the various room thermostats. The day and night control has not been disclosed in the drawing but since these devices are well known to those skilled in the art they may be readily applied, if desired. The thermostats controlling the cooling system are arranged to operate at slightly different temperatures in order to equalize the length of time the main and auxiliary comprese sor motors will be in operation. The thermostats controlling the main system are set to operate at a temperature which will be assumed to be 80 and the thermostats controlling the operation of the. auxiliary cooling apparatus that is shifted from one conditioner to the other is set to operate at 78.

The operation as it occurs during the summer when cooling is required is first described. The telechron motors I24 driving time switches I22 and I23 will be energized constantly. Consequently, these switches will be operated in a manner described above to energize the main cooling 4 apparatus associated with the conditioners through operation of switch I22 and relay I29 and the auxiliary cooling apparatus will be selectively connected to either conditioner or disconnected entirely as desired under the control of switch I23. It will be assumed that switch I22 is of the type wherein the circuit is closed during 24 hours a day but which is provided with means whereby certain days may be skipped entirely. That is, on certain days when cooling is not required, the apparatus may be de-energized. On the other hand, switch I23, as has been described above, is of the type whereby a contact is made from the middle pole of the mercury switch I26 to the contacts at opposite ends only during certain periods of the day. For purpose of illustration, it will be assumedthat contact is made between the middle and right hand poles during the forenoon; that is from 6 a. m. to 12 m., and from the middle pole to the left hand pole from 12 m. to some time such as 8 p. in.

With these assumptigns in mind, it may be noted that a circuit will be closed by means of switch I22 to energize relay I29 by connecting the latter across supply line 89 through conductors I2I and I2I, mercury switch I25 and conductor I28. Assuming the time of day to be before 6 a. m., then switch I23is in its open position and the auxiliary cooling apparatus inoperative. Energization of relay I29 will cause upward movement of its associated armature and closure of switch 92.' This effects energization of primary winding of transformer 81, connecting it directly across the supply lines through conductors 99 and 9|. After a brief interval, as determined by time delay means II2 associated with switch III, a similar circuit will ,be closed by that switch to energize primary winding, of transformer I01.

Whether or not motors 61 and 53 will be energized by the closure of these relays will in turn depend on the position of the thermostats 8| and IIII in zones II and I2, respectively. If these thermostats are in their closed position because temperatures higher than 80 obtain, then relays 88 and I88 associated therewith will be promptly energized with the resulting closure of switches 94 and H4. The closure of these switches, will energize relays 95 and H5 controlling the energization of compressor motors 53 and 61., However, if the temperature within zones II and I2 is below 80, the thermostats BI and IDI would not be in their closed position and, consequently, the respective motors would not be energized and the only result of the energization of relay I29 would be the energization of the primary windings of the above mentioned transformers. If the temperature within zone I2 rises to a value greater than 80, then thermostat I9I will close the energizing circuit for relay I98 and the energization of the latter will effect the closure of switches I I3 and H4. Closure of the former energizes the holding circuit for the relay and closure of the latter closes a circuit through conductors I I 6 and III for relay H5, the latter effecting closure of switch H9 and consequent energization of motor 61. Thereupon the cooling apparatus associated with zone I2 is set into operation and as the air flows by evaporator 58 it is cooled and distributed to the various rooms through central duct Since the damper controlling thermostats 21 and 28 in zone I2 were assumed to operate at 80", these thermostats will close an energizing circuit .for their relay windings I96 and cause operation of their associated dampers 35 and 36 to open positions in a manner that has been described previously. It may be noted further that if some particular room is below a temperature of 80 then the'thermostat positioned in that room will remain in such position that the damper associated with that room will be maintained in its closed position. In this manner cooling medium is distributed only to those of the rooms subject to unusual conditions and which require it.

When the average temperature within the zone .decreases to a temperature below 80, as indicated by thermostat IIII in zone I2,- then thermostatic element I02 moves to its right hand position and short circuits relay I08. This results in the de-energization of the relay and motor 61 until such time as the temperature within zone I2 again reaches a value above 80". The operation of the cooling means associated with conditioner I3 for zone I I is the same in all respects and will not be further described.

After six oclock in the morning, or any other desired time, time switch I23 closes a circuit between the middle and right hand poles of mercury switch I26 to place the auxiliary cooling apparatus into condition to operate. an energizing circuit for the primary of transformer I32 is closed in a manner previously described. -Assuming first that the temperature within zone II is below a value necessary to cause operation of thermostat I4I to its closed position, thereupon the only effect of the closure of switch I26 is the energization of transformer I32. If the temperature within zone II thereafter increases to a value above 78", an energizing circuit is closed for relay I36 through conductors I31 and. I39. Energization of the relay effects closure of switches I 42, I43, and I44. Closure of the first establishes a holding circuit for the relay. Closure of the second closes the energizing circuit for relay 1 through conductors I33 and I45, switch I43, conductor I46, relay I41 and con- Thereupon ductor I48. Thereupon valve 13 is operated to its open position to permit the flow of refrigerant to auxiliary evaporator 45 associated with conditioner I3. Closure of switch I44 closes an energizing circuit for relay I50 controlling the energization of compressor motor 69 associated with the auxiliary cooling apparatus. Thus, it will be seen that the auxiliary system will be placed into operation to further 'cool the air in zone I I during that period of the day when an increased capacity is required to properly cool that part of the building. In addition, it will benoted that the auxiliary apparatus is placed into operation at a.somewhat earlier time than the main cooling apparatus for zone I2 because of the fact that it is set into operation at a somewhat lower temperature. The reason for this is'that the main cooling apparatus is in operation at certain times for a greater part of each twenty-four hours, whereas the auxiliary apparatus is in operation at most for about 12 to 14 hours and, consequently, it is desirable that the auxiliary apparatus be utilized manner as to open the first closed circuit and close the circuit across the middle and left .hand

poles of I26. As a result, transformer I32 is deenergized and transformer I35, energized; switches I42, I43, and It opened; and switches I59, I60 and IN closed. If thermostat I53 assoe ciated with this system is in a position calling for cooling, it will be noted that, since this system is similar to that just described, it will operate to open valve 16 allowing the refrigerant to flow to evaporator 59 associated with conditioner I0 and also energize compressor motor 69. The operation is in all respects similar to that described and will not be described at any greater length.

Thus it will be seen that the capacity auxiliary apparatus is transferred from one conditioner to the other under the control of time switch I23 and that it will be set into operation at a tem-- perature slightly lower than that at which the main cooling apparatus associated with each zone will be set into operation.

Thus far, nothing has been said about the operation of the heating apparatus but, because of the fact that the thermostats controlling the operation of the latter are not operated into a circuit closingposition untiha temperature of 72 or less has been reached, the relays associated therewith will remain de-energized. If weather conditions change to such an extent that the temperature surrounding the various thermostats decreases to a value less than 72, then the cooling apparatus is inoperative because of the fact that the temperature is below the values, namely, 78 and 80, at which these thermostats are set to render their associated cooling apparatus inoperative.

Assuming that the temperature falls below '72", then thermostats I64 and I80 will move to the left to energize their respective'relays I10 and I86 in the manner heretofore described. Closure of these relays establishes a holding circuit for each through closure of switches HI and I01. Simultaneously, closure of switches I12 and I08 establishes energizing circuits for the reversing relays I204 associated with each of the various room thermostats, each relay in turn actuating its associated switches 200 and 203 from contact with their lower contacts into engagement with their upper contacts to thereby reverse, with respect to temperature, the effect of the room thermostats on the damper actuating control system. Therefore, the room thermostats will now operate to open the dampers on a decrease in temperature below a value of 72 and the closure of the same when the temperature is above this value.

Energization of relays I10 and I86 also results in the operation of the valves controlling the flow of steam to the heating coils of the conditioners. The relays actuate switches I13 and I90 to their closed position and simultaneously open switches I14 and I9I, thereby causing the valve motors to operate the valves to their open positions. Consequently, the air passing through the conditioner is now heated and distributed through ducts I4 and I9 to the zones. If the temperature within any of rooms A, B, D, or E falls below a value of 72 the thermostat therein will close a circuit for its associated relay I96 energizing motor I91 to operate the latter through in a manner previously described. Alternate energization and de-energization of relay I96 will therefore operate to'open and close the damper associated with the particular room. When the average temperature within the zones as indicated by thermostats I64 and I80 in rooms C and F increases to a value above 72 the thermostats will move to positions wherein relays I10 and I86 are short circuited, causing deenergization of these relays and of reversing relays 204 as well. Additionally, the switches I13 and I90 are opened and siwtches I14 and I9I closed to operate the motors of valves 43 and 51 to their opposite or closed positions to discontinue the flow of steam to the heater coils. 7

It may be desirable in certain types of systems to provide means whereby the temperature maintained within the building is kept at a lower value during the night than during the day as by pro viding thermostats therein with a day-night control. Such a system may be applied in connection with the thermostats I64 and I00 and the various room thermostats. If applied, it will be obvious to those skilled in the art that my system will operate to maintain lower temperatures whenever desired and as controlled by timing means associated with the thermostats.

As stated previously,'it often occurs that in large buildings the requirements of the various tenants are likely to be difierent. One such difference arises in systems of this type where onetenant requires a continual circulation of air through the portion of the building that he occupies. leading to each room and a damper operable from a closed to open position and vice versa continual circulation cannot be obtained. Therefore, I have provided a means whereby any space or spaces may be provided with continual circulation of air. The damper 31 in duct 24 leading to room B is interlinked with damper 34 in duct I4 in such manner that one damperwill be in its open position and the other in its closed position and that the room will be supplied witheither conditioned air or with a combination of fresh and recirculated air.

It will be obvious to those skilled in the art that my invention is not limited to thesystem described above. It maybe used in conditioning any number of zones, some of which may be provided with independent conditioners after the It is obvious that with but a single ductmanner of the conditioners described but which are provided with only a single cooling surface. Furthermore, it is not essential that the auxiliary cooling means be effective at the times stated. It may be convenient to make them effective for but two hours in the morning and a like period in the afternoon and this change could be made by merely changing the operation of time switch I23 in an obvious fashion.

In other cases it may be convenient to divide the building into more than two zones and sequentially to shift the capacity of the auxiliary cooling equipment to the various zones to compensate for the efiect of the suns rays.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an air conditioning system, the combination including. a plurality of spaces to be conditioned, an air conditioner comprising air, circulating and conditioning means, a central duct leadingtherefrom, individual branch ducts leading from the latter to each of said spaces, a central return duct and branch ducts leading from each space to said return duct, means for regulating the flow of said conditioned air to predetermined spaces through said branch ducts, thermal responsive means in each of said predetermined spaces for controlling said last mentioned means, a duct leading from a point between the air circulating and conditioning means to one of said predetermined spaces and by-passing said conditioner, and means for regulating the flow of by-passed air through said last mentioned duct, said last mentioned means being operatively associated with the regulating means controlling the flow of conditioned air through a branch duct to said one of said predetermined spaces and adapted to close said by-pass duct when the branch duct is open, and vice versa, and controlled by the thermal responsive means controlling the flow of conditioned air to said spaces whereby said space is continuously supplied with conditioned or by-passed air.

2. In an air conditioning system, a plurality of spaces to be conditioned, means including a conditioner and a central duct system with associated branch ducts for supplying said spaces with conditioned medium, means including thermal control devices located in said spaces for regulating the fiow of medium through said branch ducts to said spaces, an independent duct leading from the conditioner to a predetermined one of saidvspaces for supplying unconditioned air thereto, and additional means controlled byv the thermal control device in said predetermined space for regulating the fiow of medium through said independent duct, said flow regulating means comprising interconnected dampers in said branch and independent ducts so arranged that when one damper closes its respective duct the other opens its associated duct, whereby said space is supplied continuously with either conditioned or unconditioned air.

3. In a temperature control system, the combination including a thermostat responsive to variations in a predetermined temperature condition, means controlled by said thermostat for varying the temperature of a heat exchange medium upon variation in said temperature condition to a predetermined value, means for supplying said medium to a space including reversible means for increasing and decreasing the supply of said heat exchange medium to said space, a separately operable thermostat responsive to variations in the temperature of said space for reversing said regulating means to vary the supply of heat exchange medium to the space in accordfor reversing with respect to the temperature variations in said space the reversing control of said second thermostat on said reversible means.

4. In a heating and cooling temperature control system, the combination of reversible regulating means operable in each. direction for oppositely controlling temperature under heating and cooling conditions, means for reversing said regulating means, and means including a pair of thermal responsive devices each having a control element reversely operable between two control positions upon temperature variations in opposite directions between limits, said pair of thermal responsive devices being relatively adjustable for eifecting the reverse operations of the control element of one of said devices at temperature limits below. the lower temperature limit of the other device under heating conditions and above the upper temperature limit of the other device under cooling conditions, and concatenated reversing connections between said elements for jointly controlling the operation of said reversing means whereby said regulating means will be selectively actuated in each direction in response to temperature variations in opposite directions upon said relative adjustment of said devices.

5. In a temperature control system the combination of a reversible temperature regulating device, a reversible electric motor for operating said device, means for selectively controlling the operation of said motor including a pair of thermal responsive means, each having a thermostatic control element responsive to a different one of two predetermined temperature conditions and separately adjustable for response at different temperature values and each having a circuit controlling element controlled by the corresponding thermostatic element for operation in opposite directions between two circuit closing positions in response to opposite variations in temperature from the value to which the corresponding thermostatic element is adjusted to respond, and concatenated circuit reversing connections between said circuit controlling elements for effecting operation of said motor in predetermined opposite directions upon operation of one of said circuit controlling elements between the two circuit closing positions thereof with the other of said circuit controlling elements in one of the two circuit closing positions thereof and for effecting operation of said motor in the reversed opposite directions upon the same operation of said one circuit controlling element with said other circuit controlling element in the other of the two circuit closing positions thereof.

-6. In a zone temperature control system, the combination of a pair of thermostats, one being responsive to the temperature of one space in the zone and the other being responsive to the temperature of another space in the zone, heat exchange means controlled by said one thermostat for varying the temperature of all the spaces in the zone, temperature regulating means for modifying the action of said heat exchange means and separately operable under the control of said other thermostat for varying the temperature of said other space with respect to the temperature of said one space, and means operable under the control of said one thermostat upon a predetermined change in the temperature of said one changing means controlled by said one device for jointly varying said temperature conditions, separate temperature regulating means for modifying the action of said temperature changing means and controlled by each other of said thermal responsive devices for separately regulating the corresponding temperature condition, and

means controlled by said one temperature responsive device for reversing the control of all said other temperature responsive devices over the for supplying heat exchange medium to all said spaces, means i or heating said medium, separately operable means for cooling said medium, means including thermal responsive means responsive to the temperature in one of said spaces for starting operation of said cooling means when the temperature in said .one space exceeds a predetermined maximum value and for starting operation of said heating means when the temperature in said one space decreases below a predetermined minimum value, a separate thermostat in each of the remainder of said spaces having separate means controlled thereby for regulating the flow of said medium to the corresponding space, and

means under the control of said first mentioned thermal responsive means for efiecting operation of all said separate thermostat regulating means to increase the flow of medium to the corresponding space when the heating means is in operation and the temperature in said space decreases below a predetermined value and to increase the flow of medium to the corresponding space when said cooling means is in operation and the temperature in said space increases above a predetermined value.

9. In a multiple zone cooling system, the com bination of a pair of zones normally having maximum heat gains during different predetermined periods, separately operable cooling means for each of said'zones, separate auxiliary heat absorbing means for each of saidzo'nes having a common operating element, thermal responsive means in each zone 'for rendering said common operating element and the corresponding auxiliary heat absorbing means efiective to cool the corresponding zone upon a predetermined temperature variation in the corresponding zone, and time controlled means for rendering the thermal responsive means of one zone effective during the period of maximum heat gain of said zone, and the thermal responsive means of the other zone effective during the period of maximum heat gain of the other zone.

10. In a variable demand cooling system the combination of a pair of zones normally having maximum cooling demands during different predetermined periods, separate cooling apparatus for each zone comprising an air conditioner having means for circulating air from said conditionerto the corresponding zone, and refrigerating apparatus for cooling the air, an auxiliary refrigerating apparatus having separate heat absorbing means forcooling'the air in each of said conditioners, and time control means for oppositely controlling the separate heat absorbing means of said auxiliary apparatus to in-' crease the air cooling capacity of one of said conditioners and'decrease the air cooling capacity of the other. of said conditioners during each of said predetermined periods.

11. In a multiple 'zone cooling system, the combination of a pair of zones normally having maximum heat gains at different predetermined times, separate air conditioners for each zone, each having a-main and an auxiliary air cooling means therein, main and auxiliary thermal responsive means in each zone for selectivelyrendering the main and auxiliary cooling means of the corresponding conditioner eiT-ective and ineffective, and time controlled means synchronized with the variations in heat gain of said zones forselectively rendering a corresponding one of said auxiliary thermal responsive means effective at said different predetermined times.

12. In a multiple zone cooling system, the combination of a plurality of zones normally having maximum heat gains during different time periods, a separately operable main cooling means for each zone, thermostatic means in each zone for controlling operation of the corresponding main cooling means in accordance with predetermined temperature variations therein, a separately operable auxiliary cooling means having a separately operable cooling element for each zone, and a timing control device having a thermostatic means in each zone selectively controlled thereby for rendering the corresponding cooling element operable and effecting operation of said auxiliary cooling means during the period of maximum heat gain of the corresponding zone in accordance with predetermined temperature variations therein.

13. In a multiple zone cooling system, the combination of a plurality of zones normally having maximum heat gains during different time periods, a separate air conditioner for each zone, each having a main cooling means and a thermostatic control means therefor responsive to predetermined variations in temperature of the corresponding zone, auxiliary cooling means having a separate cooling element in each conditioner and a common operating element, valve bination of a plurality of zones normally having maximum heat gains during different time periods, a separate air conditioner for each zone,

' each having an air circulating means and a main air cooling means providedwith thermostatic control means for effecting operation of said main cooling means in accordance withpredetermined temperature variations in the corresponding zone, auxiliary cooling means having a separate cooling element in each air conditioner 7 and a common operating element therefor, each of said cooling elements having a separately operable valve for operatively connecting the element with said operating element, and means including a timing control means and a thermostatic means in each zone selectively controlled thereby for selectively controlling said valve means and selectively effecting operation of said operating element during the period of maximum heat gain of the corresponding zone and in accordance with predetermined temperature variations therein.

15. In an air conditioning system for a plurality of spaces, the combination including a central air conditioner having means for circulating air to all said spaces, means for-heating the circulated air and separately operable means for cooling the circulated air, thermal responsive means in one of said spaces for selectively operating said heating and cooling means upon variation of the temperature therein below and above predetermined limits, means including a separate thermostat in each of the remainder of said spaces for regulating the flow of conditioned air to the corresponding space, and means controlled by said first mentioned thermal responsive means for reversing with respect to temperature the regulating action of all said separate thermostats upon the selective operation of a predetermined one of said heating and cooling means.

16. In a reversible heat exchange system, the combination of complementary heat exchange means separately operable for oppositely varying the temperature differential of a circulating heat exchange medium, means including a valve movable between limits for varying the flow of said medium, reversible actuating means for moving said valve between said limits, thermal responsive means for reversing said reversible actuating means under opposite heat exchange conditions, independent thermal responsive means for selectively initiating and terminating operation of said heat exchange means, and means under the control of said independent thermal responsive means for reversing with respect to temperature variations the reversing control action of said first mentioned thermal responsive means on said reversible actuating means upon initiation and termination of the operation of a predetermined one of said heat exchange means.

1'7. In an air conditioning system, the combination of continuously operable means for circulating air to a plurality of spaces, complementary heat exchange means separately operable for oppositely varying the temperature diiferential of the circulated air, thermal responsive means in one of said spaces for selectively initiating and terminating operation of said heat exchange means to regulate the temperature of said one space, means including a thermal responsive device in another of said spaces and reversible valve means having reversible control connections with said thermal responsive device for regulating the flow of circulated air to said other space to regulate the temperature of said other space, and means for reversing said control connections upon initiation and termination of operation of a predetermined one of said heat exchange means.

18. In combination, complementary heat exchange means separately operable for oppositely varying the temperature differential of a heat exchange medium, means including a valve movable between limits for varying the flow of said medium to regulate a variable temperature condition, reversible actuating means for moving said valve between said limits, means including a temperature responsive device responsive to variations in said variable temperature condition and adjustable for reversing said reversible actuating means at the minimum and maximum limits of two separated temperature ranges, and cooperating temperature responsive means for selectively initiating and terminating operation of said I heat exchange means when said predetermined temperature condition varies from a predetermined temperature value intermediate said tem perature ranges, and reversing means interconnected between said temperature responsive device and said reversible actuating means for automatically reversing the reversing control of said temperature responsive device over said reversible actuating means upon the initiation and termi nation of operation of a predetermined one of said heat exchange means.

19. In a reversible heat exchange system, the

combination of complementary heat exchange means separately operable for oppositely varying the temperature diiferential of a circulating heat exchange medium to regulate a variable temperature condition, thermal responsive means responsive to said condition for selectively controlling operation of said heat exchange means, valve means movable between limits for varying the flow of said medium to regulate a different temperature condition, reversible actuating means for moving said valve means between said limits, thermal responsive means responsive to variations in said difierent temperature conditions for controlling said reversible actuating means, and means under the control of said first thermal responsive means for reversing with respect to temperature the action of said second mentioned thermal responsive means on said reversible actuating means upon predetermined selective operation of said heat exchange means.

EDWARD A. BAILEY.