Patent Publication Number: US-2022235961-A1

Title: Air conditioning system

Description:
TECHNICAL FIELD 
     The present disclosure relates to an air conditioning system provided with a plurality of fan units. 
     BACKGROUND ART 
     Among air conditioning systems of the prior art that provide air conditioning inside a building, there exists an air conditioning system that supplies conditioned air to a plurality of places inside a building using ducts, as described in Patent Literature 1 (JP H11-132489 A) for example. 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     However, the air conditioning system described in Patent Literature 1 describes fan unit control content that does not account for energy saving on the heat source side. In such an air conditioning system that uses ducts to supply conditioned air to a plurality of places inside a building, one challenge is to control the supply of conditioned air to moderate the energy consumption by the heat source side in the supply of conditioned air using ducts. 
     Solution to Problem 
     An air conditioning system according to a first aspect is an air conditioning system including a heat exchanger unit including a use side heat exchanger, and configured to generate conditioned air through heat exchange in the use side heat exchanger and supply the conditioned air to an air conditioned space through a plurality of distribution flow paths that communicate with the heat exchanger unit. The air conditioning system is provided with a controller, a plurality of ducts, and a plurality of fan units. The plurality of ducts are used to distribute conditioned air that has passed through the use side heat exchanger of the heat exchanger unit. The plurality of fan units are provided in correspondence with the plurality of ducts, and supply conditioned air from the heat exchanger unit to the air conditioned space through the plurality of ducts. A plurality of actuators are configured to be changeable the air supply amount of conditioned air to be supplied to the air conditioned space. Each of the plurality of ducts is disposed in one of a plurality of distribution flow paths. Each of the plurality of fan units includes a first fan, and is disposed in one of the plurality of distribution flow paths. Each of the plurality of actuators is disposed in one of the plurality of distribution flow paths. By controlling the plurality of actuators, the controller controls the air supply amount for each of the plurality of fan units. 
     In the air conditioning system according to the first aspect, because the controller controls the air supply amounts of the plurality of fan units, the air flow volume passing through the use side heat exchanger can be adjusted such that heat is exchanged efficiently in the use side heat exchanger, and energy consumption can be moderated. 
     An air conditioning system according to a second aspect is the system according to the first aspect, in which the controller controls the plurality of actuators in accordance with a plurality of instructions related to the air supply amounts of the plurality of fan units. 
     In the air conditioning system according to the second aspect, the controller controls the plurality of actuators according to instructions related to the air supply amounts with respect to the plurality of actuators, and adjusts the air flow volume passing through the use side heat exchanger such that heat is exchanged efficiently in the use side heat exchanger to moderate energy consumption. 
     An air conditioning system according to a third aspect is the system according to the second aspect, in which the controller includes a main controller that transmits the plurality of instructions and at least one sub-controller that receives the plurality of instructions from the main controller. The at least one sub-controller controls the plurality of actuators on a basis of the plurality of instructions. 
     In the air conditioning system according to the third aspect, because the main controller controls the plurality of actuators through at least one sub-controller, the control by the main controller is simplified, making it easy to change the duct design and layout of the system. 
     An air conditioning system according to a fourth aspect is the system according to the third aspect, in which each of the plurality of actuators is a fan motor that drives the first fan. 
     An air conditioning system according to a fifth aspect is the system according to the fourth aspect, in which the at least one sub-controller is a plurality of sub-controllers, each of the plurality of fan units includes an air flow volume detector that detects the air flow volume passing through each unit, and each of the plurality of sub-controllers controls a rotation speed of the fan motor such that the air flow volume detected by the air flow volume detector approaches the air supply amounts indicated by the instructions from the main controller. 
     In the air conditioning system according to the fifth aspect, the air supply amount of each fan unit can be controlled by each sub-controller reliably. 
     An air conditioning system according to a sixth aspect is the system according to any one of the first to fifth aspects in which the controller calculates the air supply amounts of each of the fan units from a temperature difference between an indoor air temperature adjusted by each of the plurality of fan units and a set temperature, and a fan temperature, and determines the plurality of instructions on a basis of the calculated air supply amounts. 
     In the air conditioning system according to the sixth aspect, temperature control of the air conditioned space is achieved easily by changing the air supply amount. 
     An air conditioning system according to a seventh aspect is the system according to any one of the first to sixth aspects, in which the heat exchanger unit includes a second fan, and the controller controls the second fan on a basis of the air supply amounts of the plurality of fan units. 
     In the air conditioning system according to the seventh aspect, the controller can control the second fan to an appropriate value to match the air supply amounts of the plurality of first fans, and moderate the energy consumption of the air conditioning system. 
     An air conditioning system according to an eighth aspect is the system according to the first or second aspect, in which the heat exchanger unit includes a second fan, the controller includes a main controller that controls the plurality of actuators in accordance with a plurality of instructions related to the air supply amounts of the plurality of fan units, and a plurality of sub-controllers that receive the plurality of instructions transmitted by the main controller and control the plurality of actuators, and the main controller controls the second fan to be a predetermined output with respect to a total combined air supply amount indicated by the plurality of instructions. 
     In the air conditioning system according to the eighth aspect, the controller easily controls the second fan to set the output of the second fan to an appropriate value to match the air supply amounts of the plurality of first fans. 
     An air conditioning system according to a ninth aspect is the system according to the first or second aspect, in which the controller includes at least one sub-controller that controls the plurality of actuators and a main controller that communicates with the at least one sub-controller, and the main controller is disposed in the heat exchanger unit. 
     In the air conditioning system according to the ninth aspect, because the main controller is disposed in the heat exchanger unit, it is sufficient to construct a network connecting the main controller and the plurality of actuators to match the flow of conditioned air supplied from the heat exchanger unit, and therefore the network for transmitting the instructions from the main controller can be constructed easily using the heat exchanger unit as the starting point. 
     An air conditioning system according to a 10th aspect is the system according to the first or second aspect, in which the controller includes at least one sub-controller that controls the plurality of actuators and a main controller that communicates with the at least one sub-controller, and the main controller is disposed in one of the plurality of fan units. 
     In the air conditioning system according to the 10th aspect, because the main controller is disposed in one of the plurality of fan units, an air conditioning system including the main controller in one of the plurality of fan units can be formed by connecting a network of the plurality of fan units, and the air conditioning system can be constructed easily. 
     Note that when configuring the air conditioning system according to the 10th aspect, in the case where two or more main controllers exist, it is sufficient for at least one of the two or more main controllers to exist in one of the plurality of fan units. 
     An air conditioning system according to an 11th aspect is the system according to the first or second aspect, in which the controller includes at least one sub-controller that controls the plurality of actuators and a main controller that communicates with the at least one sub-controller, and the main controller is disposed in a location other than the heat exchanger unit or the plurality of fan units. 
     In the air conditioning system according to the 11th aspect, because the main controller is disposed in a location other than the heat exchanger unit or the plurality of fan units, the installation of the main controller is not restricted by the heat exchanger unit and the plurality of fans units, thereby increasing the degree of freedom in the installation of the main controller and making it easy to handle the main controller. 
     An air conditioning system according to a 12th aspect is the system according to any one of the first and the ninth to 11th aspects, in which air passing through the use side heat exchanger is produced by only air suction force of the plurality of fan units. 
     The air conditioning system according to the 12th aspect is configured to generate an air flow passing through the use side heat exchanger using only the air suction force of the plurality of fan units, and a power source for generating an air flow in the heat exchanger unit does not have to be provided, therefore costs can be reduced compared to the case of providing a power source for generating an air flow in the heat exchanger unit. 
     An air conditioning system according to a 13th aspect is the system according to any one of the first and the ninth to 12th aspects, in which the heat exchanger unit includes at least one of a heat medium temperature sensor that detect the temperature of a heat medium flowing through the use side heat exchanger or a pipe connected to the use side heat exchanger, and an intake temperature sensor that detects the temperature of air suctioned into the heat exchanger unit. The heat medium temperature sensor and/or the intake temperature sensor is connected to the main controller. 
     An air conditioning system according to a 14th aspect is the system according to the 13th aspect, in which the main controller uses a detected value from at least one of the heat medium temperature sensor and the intake temperature sensor to determine an instruction related to increasing or decreasing the air supply amounts. 
     In the air conditioning system according to the 14th aspect, a detected value from at least one of the heat medium temperature sensor and the intake temperature sensor is used to determine the instruction related to increasing or decreasing the air supply amount, thereby making it easy for the main controller to output instructions causing the plurality of fan units to supply air to meet the operating condition of the heat exchanger unit. 
     An air conditioning system according to a 15th aspect is the system according to any one of the first and the ninth to 14th aspects, further including a remote controller including a set temperature function that sets a temperature of the air conditioned space and a function that detects an indoor temperature of the air conditioned space, in which the main controller uses the set temperature of the remote controller and the indoor temperature detected by the remote controller to determine an instruction related to increasing or decreasing the air supply amounts. 
     In the air conditioning system according to the 15th aspect, because the main controller uses the set temperature of the remote controller and the indoor temperature detected by the remote controller to determine the instruction related to increasing or decreasing the air supply amount, the main controller can issue an instruction causing the temperature of the air conditioned space to approach the set temperature. 
     An air conditioning system according to a 16th aspect is the system according to any one of the first and ninth to fifteenth aspects, further including: a compressor that compresses a refrigerant; a heat source side heat exchanger that exchanges heat with the refrigerant circulating through the use side heat exchanger; and an expansion valve that causes the refrigerant flowing between the use side heat exchanger and the heat source side heat exchanger to expand, in which the main controller is connected to the compressor and/or the expansion valve to control a system operation. 
     In the air conditioning system according to the 16th aspect, because the main controller is connected to a compressor and/or an expansion valve to control system operation, the system operation can be controlled appropriately by increasing or decreasing the air supply amount and controlling the rotation speed of the compressor and/or the opening degree of the expansion valve to achieve a refrigerant circulation rate derived by arithmetic operations for example, and the increasing or decreasing of the air supply amount can be controlled while performing a refrigeration cycle suitable for the refrigerant circulating through the use side heat exchanger and the heat source side heat exchanger. 
     An air conditioning system according to a 17th aspect is the system according to any one of the first and the ninth to 15th aspects, further including: a compressor that compresses a refrigerant; a heat source side heat exchanger that exchanges heat with the refrigerant circulating through the use side heat exchanger; and an expansion valve that causes the refrigerant flowing between the use side heat exchanger and the heat source side heat exchanger to expand, in which the main controller calculates an operating frequency of the compressor and/or an opening degree of the expansion valve from a total air flow volume of air passing through the use side heat exchanger obtained by adding up the air supply amounts transmitted from all fan units, and the temperature of air suctioned into the heat exchanger unit. 
     An air conditioning system according to a 18th aspect is the system according to any one of the first and the ninth to 15th aspects, further including: a compressor that compresses a refrigerant; a heat source side heat exchanger that exchanges heat with the refrigerant circulating through the use side heat exchanger; and an expansion valve that causes the refrigerant flowing between the use side heat exchanger and the heat source side heat exchanger to expand, in which the main controller controls actuators on the basis of information indicating the operating frequency of the compressor and/or an opening degree of the expansion valve. 
     In the air conditioning system according to the 18th aspect, because the main controller controls the actuators on the basis of the rotation speed of the compressor and/or the opening degree of the expansion valve, the increasing or decreasing of the air supply amount can be controlled while performing a refrigeration cycle suitable for the refrigerant circulating through the use side heat exchanger and the heat source side heat exchanger. 
     An air conditioning system according to a 19th aspect is the system according to any one of the first and the ninth to 18th aspects, in which the main controller controls the air flow volume passing through the use side heat exchanger with an actuator in at least one duct among the plurality of ducts while adjusting an actuator in the at least one duct such that the conditioned air proceeding from the heat exchanger unit toward the air conditioned space in the at least one duct does not flow back. 
     In the air conditioning system according to the 19th aspect, because the main controller controls the air flow volume passing through the use side heat exchanger with an actuator in at least one duct while adjusting an actuator in at least one duct such that conditioned air proceeding from the heat exchanger unit toward the plurality of outlets in at least one duct does not flow back, a drop in heat exchange efficiency due to backflow of the conditioned air in the at least one duct can be prevented. 
     An air conditioning system according to a 20th aspect is the system according to the 19th aspect, further including: a plurality of dampers or a plurality of air deflectors, in which each of the plurality of dampers or the plurality of air deflectors is disposed in one of the plurality of distribution flow paths, the plurality of actuators include a plurality of motors that drive the plurality of dampers or the plurality of air deflectors, and the main controller adjusts an opening degree of a damper or an air deflector in at least one duct among the plurality of ducts such that the conditioned air proceeding from the heat exchanger unit toward the air conditioned space in the at least one duct does not flow back. 
     In the air conditioning system according to the 20th aspect, because the conditioned air is controlled not to flow back in the at least one duct by adjusting the opening degree of a damper or an air deflector, a drop in heat exchange efficiency due to backflow of the conditioned air in the at least one duct can be prevented easily. 
     The air conditioning system according to the 21st aspect is the system according to the 19th or 20th aspect, in which the plurality of actuators include a plurality of fan motors configured to change an individual air supply amount of each of the plurality of fan units, and the main controller adjusts a rotation speed of a fan motor in at least one duct among the plurality of ducts such that the conditioned air proceeding from the heat exchanger unit toward the air conditioned space in the at least one duct does not flow back. 
     In the air conditioning system according to the 21st aspect, because the conditioned air is controlled not to flow back in the at least one duct by adjusting the rotation speed of the fan motor in the at least one duct, a drop in heat exchange efficiency due to backflow of the conditioned air in the at least one duct can be prevented easily. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating an overview of the configuration of an air conditioning system. 
         FIG. 2  is a schematic perspective view of one example of connecting a heat exchanger unit, ducts, fan units, and outlet units. 
         FIG. 3  is a cross section view of one example of a fan in a fan unit. 
         FIG. 4  is a block diagram illustrating one example of a control subsystem. 
         FIG. 5  is a schematic view of another example of the configuration of a fan unit. 
         FIG. 6  is a block diagram for explaining the connection relationship between a main controller and a fan controller of a modification 1O. 
         FIG. 7  is a block diagram for explaining an example of the connection relationship between a main controller and a fan controller of a modification 1P. 
         FIG. 8  is a block diagram for explaining another example of the connection relationship between a main controller and a fan controller of a modification 1P. 
         FIG. 9  is a block diagram for explaining an example of the connection relationship between a main controller and a fan controller of a modification 1Q. 
         FIG. 10  is a block diagram for explaining another example of the connection relationship between a main controller and a fan controller of a modification 1Q. 
         FIG. 11  is a block diagram for explaining still other example of the connection relationship between a main controller and a fan controller of a modification 1Q. 
         FIG. 12  is a block diagram for explaining another example of the connection relationship between a main controller and a fan controller of a modification 1R. 
         FIG. 13  is a conceptual diagram showing the configuration of an air conditioning system according to a third embodiment. 
         FIG. 14  is a block diagram for explaining the configuration of a controller. 
         FIG. 15  is a conceptual diagram showing another example of the configuration of an air conditioning system according to a modification. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     (1) Overall Configuration 
     An air conditioning system  1  illustrated in  FIG. 1  supplies conditioned air to an air conditioned space SA. Examples of the air conditioned space SA include rooms RA 1  and RA 2  in a building BL, or the like. The rooms RA 1  and RA 2  are partitioned by a partitioning wall  78 . Here, descriptions will be given in a case where the air conditioned spaces SA are two rooms RA 1  and RA 2 , however, the air conditioning system  1  may be provided in corresponding to rooms in various size, various shape, and various numbers. It is preferable that the air conditioned spaces SA to which the air conditioning system  1  supplies conditioned air be surrounded (front and back, up and down, and left and right) by wall surfaces like the rooms RA 1  and RA 2 . Note that the air conditioned spaces SA are not limited to the rooms RA 1  and RA 2 , but may be, for example, corridors, stairs, and entrances. The air conditioned space SA may be a single space such as a large hall, or a plurality of spaces such as a plurality of rooms partitioned from each other, for example. 
     As illustrated in  FIG. 1 , the air conditioning system  1  is provided with a heat exchanger unit  10 , a plurality of ducts  20 , a plurality of fan units  30 , and a controller  300  (see  FIG. 5 ). The air conditioning system  1  generates conditioned air through heat exchange in the heat exchanger unit  10 , and supplies the generated conditioned air to the air conditioned space SA through a plurality of distribution flow paths. Each of the plurality of ducts  20  is disposed in one of the plurality of distribution flow paths. Each of the plurality of fan units  30  is disposed in one of the plurality of distribution flow paths. Note that when distinguishing one among the plurality of ducts  20 , a letter of the alphabet is appended, like the duct  20   a . Here, four ducts  20   a  to  20   d  are illustrated as the ducts  20 . Also, four fan units  30   a  to  30   d  are illustrated as the fan units  30 . Also, four outlet units  70   a  to  70   d  and four remote controllers  60   a  to  60   d  are illustrated as the outlet units  70  and the remote controllers  60 , respectively. Each of the plurality of outlet units  70   a  to  70   d  is disposed in one of the plurality of distribution flow paths. 
     The heat exchanger unit  10  includes a use side heat exchanger  11 . The heat exchanger unit  10  has a function to generate conditioned air through heat exchange in the use side heat exchanger  11 . One end  21  of each of the plurality of ducts  20  is connected to the heat exchanger unit  10 . The plurality of ducts  20  are a plurality of pipes that send conditioned air generated by the heat exchanger unit  10 , and include a function of distributing the conditioned air. In other words, the plurality of ducts  20  are used to distribute conditioned air that has passed through the use side heat exchanger  11  of the heat exchanger unit  10 . 
     The plurality of fan units  30  are connected to another end  22  of the plurality of ducts  20 . Here, the fan unit  30   a  is connected to the corresponding duct  20   a  connected to the heat exchanger unit  10 , for example. Similarly, the fan units  30   b  to  30   d  are also connected to the corresponding ducts  20   b  to  20   d , respectively. Although a case where each duct  20  has a single one end  21  and a single other end  22  is described herein, a single duct  20  may also branch from a single one end  21  into a plurality of other ends  22 , and the fan unit  30  may be connected respectively to each of the plurality of other ends  22  branching in this way. Also, the fan units  30   a  to  30   d  are connected to the outlet units  70   a  to  70   d  and the remote controllers  60   a  to  60   d.    
     The air conditioning system  1  includes a plurality of air outlets  71  disposed in the air conditioned space SA. Each fan unit  30  supplies conditioned air to each corresponding air outlet  71 . To supply conditioned air to each air outlet  71 , each fan unit  30  draws in conditioned air from the heat exchanger unit  10  through each duct  20 . To draw in conditioned air, each fan unit  30  includes a fan  32  inside a casing  31  of each fan unit  30 . Each fan  32  sends air from the other end  22  of each duct  20  toward each air outlet  71 . One or a plurality of fans  32  may be included in each fan unit  30 . Here, one each of the fans  32   a  to  32   d  is respectively provided in the casing  31  of each of the fan units  30   a  to  30   d.    
     Each fan unit  30  is configured to change the individual air supply amounts of the conditioned air to be supplied to each air outlet  71  with an actuator. The air supply amount is the amount of air supplied to the air conditioned space SA per unit time. Here, a fan motor  33  with a variable rotation speed is the actuator. Here, four fan motors  33   a  to  33   d  are configured such that the rotation speed can be changed individually, and by causing the fan motors  33   a  to  33   d  to change the respective rotation speed individually, the fan units  30   a  to  30   d  can change the air supply amounts individually. 
     By controlling the plurality of actuators, the controller  300  controls the air supply amount of each of the plurality of fan units  30 . More specifically, the main controller  40  of the controller  300  controls the plurality of actuators in accordance with a plurality of instructions related to the air supply amounts of the plurality of fan units  30 . Consequently, the air conditioning system  1  according to the first embodiment outputs an instruction related to increasing or decreasing the air supply amount from the main controller  40  to the plurality of actuators. The “instruction related to increasing or decreasing the supply air flow volume” is not limited to the case causing the supply air flow volume to increase or decrease by outputting an instruction causing the parameter of the supply air flow volume to increase or decrease directly. For example, in the case where the supply air flow volume increases or decreases as a result of outputting an instruction causing a wind speed parameter of the fan units  30  to increase or decrease, and the wind speed increases or decreases according to the increase or decrease of the wind speed parameter, the instruction causing the wind speed parameter to increase or decrease is included in the “instruction related to increasing or decreasing the supply air flow volume”. Also, in the case where the supply air flow volume increases or decreases as a result of outputting an instruction causing a parameter of differential pressure in a predetermined location in the heat exchanger unit  10 , the ducts  20 , and the fan units  30  to increase or decrease, and the differential pressure parameter increases or decreases, the instruction causing the differential pressure parameter to increase or decrease is included in the “instruction related to increasing or decreasing the supply air flow volume”. As described above, not only the case of issuing an instruction for directly increasing or decreasing the supply air flow volume but also the case of issuing an instruction for indirectly increasing or decreasing the supply air flow volume are included in the “instruction related to increasing or decreasing the supply air flow volume”. A control system of the air conditioning system  1 , including the main controller  40  of the controller  300 , will be described later. 
     In addition to the above configuration, the air conditioning system  1  is provided with a heat source unit  50 , the remote controllers  60 , the outlet units  70 , an inlet unit  80 , and various sensors. The sensors provided in the air conditioning system  1  will be described later. 
     (2) Detailed Configuration 
     (2-1) Heat Exchanger Unit  10   
     The heat exchanger unit  10  is provided with the use side heat exchanger  11 , a hollow housing  12  that houses the use side heat exchanger  11 , and the main controller  40 . The housing  12  includes an air inflow port  12   a  connected to an inlet  81  and a plurality of air outflow ports  12   b  connected to the plurality of ducts  20 . Here, the case of a single air inflow port  12   a  is illustrated, but a plurality of air inflow ports  12   a  may also be provided. The use side heat exchanger  11  is a fin-and-tube heat exchanger, for example, and causes heat to be exchanged between air passing between heat transfer fins and a refrigerant flowing through heat transfer tubes. When air suctioned from the air inflow port  12   a  passes through the use side heat exchanger  11 , the air exchanges heat with the refrigerant (heat medium) passing through the use side heat exchanger  11 , and conditioned air is generated. The conditioned air generated by the use side heat exchanger  11  is suctioned into each of the ducts  20   a  to  20   b  from the air outflow ports  12   b.    
     The heat exchanger unit  10  is not provided with a fan. The reason why the heat exchanger unit  10  can suction air from the air inflow port  12   a  is that negative pressure exists inside the heat exchanger unit  10  due to the plurality of ducts  20  suctioning air from all of the plurality of air outflow ports  12   b.    
     (2-2) Ducts  20   
     The plurality of ducts  20  including the function of distributing conditioned air are connected to the plurality of air outflow ports  12   b  of the heat exchanger unit  10  and to the plurality of fan units  30 . Here, the case where each of the fan units  30  and each of the outlet units  70  are connected directly is described, but the ducts  20  may also be disposed between the fan units  30  and the outlet units  70 , such that the fan units  30  and the outlet units  70  are connected by the ducts  20 . 
     Metal pipes having a fixed shape or pipes having a freely bendable material may be used as the ducts  20 . By joining such ducts  20  together, various arrangements of the heat exchanger unit  10 , the plurality of fan units  30 , and the plurality of outlet units  70  are possible. 
     In  FIG. 2 , the heat exchanger unit  10 , four fan units  30 , and four outlet units  70  connected in a ceiling-concealed space AT are schematically illustrated. The heat exchanger unit  10 , fan units  30 , and outlet units  70  configured in this way are easily formed thinly, and therefore may also be disposed in a space under the floor of rooms RM 1  and RM 2 . 
     (2-3) Fan Unit  30   
     For the fan  32  provided in each fan unit  30 , a centrifugal fan may be used, for example. The centrifugal fan used as the fan  32  may be a sirocco fan, for example. The casing  31  provided in each fan unit  30  includes an intake port  36  and an exhaust port  37 . The other end  22  of each duct  20  is connected to the intake port  36  of each casing  31 . The outlet of each fan  32  and the corresponding outlet unit  70  are connected to the exhaust port  37  of each casing  31 . Conditioned air blown out from the fan  32  passes through the outlet unit  70  and is blown out from the air outlet  71 . 
     A fan controller  34  is attached to the casing  31 . Here, all of the fan controllers  34  are connected to the main controller  40 . 
     In  FIG. 3 , a sirocco fan is illustrated as one example of the fan  32 . The rotation speed of the fan motor  33  that causes a fan rotor  35  of the fan  32  to rotate can be changed. Consequently, by changing the rotation speed of the fan motor  33 , the amount of air supplied by the fan  32  can be changed. The fan controller  34  is connected to the fan motor  33 , and is capable of controlling the rotation speed of the fan motor  33 . 
     Each fan unit  30  is provided with a differential pressure sensor  121  that functions as an air flow volume detector described later, and each fan controller  34  is capable of automatically correcting the rotation speed of the fan motor  33  needed to produce the necessary air supply amount, even if the air resistance occurring in the ducts  20  to each fan unit  30  is different depending on the duct length. However, such a correction function does not have to be included in the fan unit  30  in some cases. 
     (2-4) Heat Source Unit  50   
     The heat source unit  50  supplies heat energy demanded by the heat exchange in the use side heat exchanger  11  of the heat exchanger unit  10 . The air conditioning system  1  illustrated in  FIG. 1  causes a refrigerant to circulate between the heat source unit  50  and the heat exchanger unit  10 , and thereby performs a vapor compression refrigeration cycle. The heat source unit  50  and the heat exchanger unit  10  form a refrigeration cycle apparatus that performs the vapor compression refrigeration cycle. In the example illustrated in  FIG. 1 , the heat source unit  50  is disposed on the outside of the building BL and treats outdoor air as the heat source, but the installation location of the heat source unit  50  is not limited to the outside of the building BL. 
     The heat source unit  50  is provided with a compressor  51 , a heat source side heat exchanger  52 , an expansion valve  53 , a four-way valve  54 , a heat source side fan  55 , a heat source controller  56 , and in-unit refrigerant pipes  57  and  58 . A discharge port of the compressor  51  is connected to a first port of the four-way valve  54 , and a suction port of the compressor  51  is connected to a third port of the four-way valve  54 . The compressor  51  compresses a refrigerant in a gaseous state (hereinafter also referred to as a gas refrigerant) or a refrigerant in a gas-liquid two-phase state suctioned from the suction port, and discharges the compressed refrigerant from the discharge port. The compressor  51  includes a built-in compressor motor whose rotation speed (or operating frequency) can be changed by inverter control, for example. The compressor  51  is capable of changing the amount of discharged refrigerant per unit time by changing the operating frequency. 
     The second port of the four-way valve  54  is connected to one of the ports of the heat source side heat exchanger  52 , while the fourth port is connected to the in-unit refrigerant pipe  58 . During the cooling operation, as illustrated by the solid lines, the four-way valve  54  causes the refrigerant to flow from the first port to the second port to send the refrigerant discharged from the compressor  51  to the heat source side heat exchanger  52 , and causes the refrigerant to flow from the fourth port to the third port to send the refrigerant from the use side heat exchanger  11  through an in-unit refrigerant pipe  132 , a connection pipe  92 , and the in-unit refrigerant pipe  58  to the suction port of the compressor  51 . During the heating operation, as illustrated by the dashed lines, the four-way valve  54  causes the refrigerant to flow from the first port to the fourth port to send the refrigerant discharged from the compressor  51  through the in-unit refrigerant pipe  58 , the connection pipe  92 , and the in-unit refrigerant pipe  132  to the use side heat exchanger  11 , and causes the refrigerant to flow from the second port to the third port to send the refrigerant from the heat source side heat exchanger  52  to the suction port of the compressor  51 . The heat source side heat exchanger  52  is a fin-and-tube heat exchanger, for example, and causes heat to be exchanged between air passing between heat transfer fins and a refrigerant flowing through heat transfer tubes. 
     The other port of the heat source side heat exchanger  52  is connected to one end of the expansion valve  53 , and the other end of the expansion valve  53  is connected to one of the ports of the use side heat exchanger  11  through the in-unit refrigerant pipe  57 , a connection pipe  91 , and an in-unit refrigerant pipe  131 . The other port of the use side heat exchanger  11  is connected to the in-unit refrigerant pipe  132 . 
     By connecting the heat source unit  50  and the heat exchanger unit  10  as above, a refrigerant circuit  200  is formed. During the cooling operation in the refrigerant circuit  200 , a refrigerant flows through the compressor  51 , the four-way valve  54 , the heat source side heat exchanger  52 , the expansion valve  53 , the use side heat exchanger  11 , the four-way valve  54 , and the compressor  51  in the above order. Also, during the heating operation in the refrigerant circuit  200 , a refrigerant flows through the compressor  51 , the four-way valve  54 , the use side heat exchanger  11 , the expansion valve  53 , the heat source side heat exchanger  52 , the four-way valve  54 , and the compressor  51  in the above order. 
     (2-4-1) Circulation of Refrigerant During Cooling Operation 
     During the cooling operation, a gas refrigerant compressed by the compressor  51  is sent to the heat source side heat exchanger  52  through the four-way valve  54 . The refrigerant transfers heat in the heat source side heat exchanger  52  to air sent by the heat source side fan  55 , expands and is decompressed by the expansion valve  53 , and is sent to the use side heat exchanger  11  by passing through the in-unit refrigerant pipe  57 , the connection pipe  91 , and the in-unit refrigerant pipe  131 . The low-temperature and low-pressure refrigerant sent from the expansion valve  53  exchanges heat in the use side heat exchanger  11  to take heat from air sent from the inlet  81 . The gas refrigerant or two-phase gas-liquid refrigerant that has exchanged heat in the use side heat exchanger  11  passes through the in-unit refrigerant pipe  132 , the connection pipe  92 , the in-unit refrigerant pipe  58 , and the four-way valve  54 , and is suctioned into the compressor  51 . The conditioned air that has lost heat in the use side heat exchanger  11  passes through the plurality of ducts  20 , the plurality of fan units  30 , and the plurality of air outlets  71 , and is blown out into the rooms RA 1  and RA 2 , thereby cooling the rooms RA 1  and RA 2 . 
     During the cooling operation, to keep liquid compression from occurring in the compressor  51 , a control is performed to adjust the opening degree of the expansion valve  53  such that the degree of superheating of the refrigerant suctioned into the suction port of the compressor  51  matches a target degree of superheating, for example. In addition, to enable processing of a cooling load while such adjustment of the opening degree of the expansion valve  53  is being performed, a control to change the operating frequency of the compressor  51  is performed. The degree of superheating is calculated by subtracting the evaporation temperature of the refrigerant inside the use side heat exchanger from the temperature of the gas refrigerant sent out from the use side heat exchanger  11 , for example. 
     (2-4-2) Circulation of Refrigerant During Heating Operation 
     During the heating operation, a gas refrigerant compressed by the compressor  51  is sent to the use side heat exchanger  11  through the four-way valve  54  and the in-unit refrigerant pipe  58 , the connection pipe  92 , and the in-unit refrigerant pipe  132 . The refrigerant exchanges heat in the use side heat exchanger  11  to transfer heat to air sent from the inlet  81 . The refrigerant that has exchanged heat in the use side heat exchanger  11  is sent to the expansion valve  53  through the in-unit refrigerant pipe  131 , the connection pipe  91 , and the in-unit refrigerant pipe  57 . The low-temperature and low-pressure refrigerant expands and is decompressed by the expansion valve  53 , is sent to the heat source side heat exchanger  52  and exchanges heat in the heat source side heat exchanger  52  to obtain heat from air sent by the heat source side fan  55 . The gas refrigerant or two-phase gas-liquid refrigerant that has exchanged heat in the heat source side heat exchanger  52  passes through the four-way valve  54  and is suctioned into the compressor  51 . The conditioned air that has gained heat in the use side heat exchanger  11  passes through the plurality of ducts  20 , the plurality of fan units  30 , and the plurality of air outlets  71 , and is blown out into the rooms RA 1  and RA 2 , thereby heating the rooms RA 1  and RA 2 . 
     During the heating operation, a control is performed to adjust the opening degree of the expansion valve  53  such that the degree of subcooling of the refrigerant at the exit port of the use side heat exchanger  11  (the in-unit refrigerant pipe  131 ) matches a target degree of superheating, for example. In addition, to enable processing of a heating load while such adjustment of the opening degree of the expansion valve  53  is being performed, a control to change the operating frequency of the compressor  51  is performed. The degree of subcooling of the use side heat exchanger  11  is calculated by subtracting the temperature of the liquid refrigerant exiting the use side heat exchanger  11  from the condensation temperature of the refrigerant inside the use side heat exchanger  11 , for example. 
     The outlet unit  70  is attached to a ceiling CE with the air outlet  71  pointed downward, for example. Here, a case in which the outlet unit  70  is attached to the ceiling CE is illustrated as an example, but the outlet unit  70  may also be attached to a wall for example, and the installation location of the outlet unit  70  is not limited to the ceiling CE. 
     (2-5) Outlet Unit  70   
     The outlet unit  70  is provided with an air filter  73  inside a hollow casing  72 . The outlet units  70   a  to  70   d  are connected to the fan units  30   a  to  30   d , respectively. Conditioned air sent from the fan unit  30  passes through the air filter  73  and is blown out from the air outlet  71 . Here, a case where the outlet unit  70  is provided with the air filter  73  is described, but the configuration of the outlet unit  70  does not have to include the air filter  73 . 
     In addition, the outlet unit  70  is provided with an air deflector  74  inside the hollow casing  72 . The outlet unit  70  is provided with an air deflector motor  75  for driving the air deflector  74 . Here, the air deflector motor  75  for driving the air deflector  74  is an actuator. The air deflector  74  can be moved by the air deflector motor  75  and thereby adjust the wind direction. Furthermore, the air deflector  74  may also be moved to a position that closes off the air outlet  71 . The air deflector motor  75  is connected to the fan controller  34  of the fan unit  30 , for example. Consequently, the fan controller  34  is capable of controlling the wind direction and the opening or closing of the air outlet  71 . Here, a case where the outlet unit  70  is provided with the air deflector  74  and the air deflector motor  75  is described, but the configuration of the outlet unit  70  does not have to include the air deflector  74  and the air deflector motor  75 . 
     The inlet unit  80  is attached to the wall of the building BL with the inlet  81  pointed toward outside the building BL, for example. Here, the case where the inlet unit  80  is attached to the building BL is illustrated as an example, but the inlet unit  80  may also be attached to the building BL for example, and the installation location of the inlet unit  80  is not limited to the wall of the building BL. 
     The inlet unit  80  is provided with an air filter  83  inside a hollow casing  82 . Air sent to the heat exchanger unit  10  is taken in from the inlet  81  through the air filter  83 . Here, a case where the inlet unit  80  is provided with the air filter  83  is described, but the configuration of the inlet unit  80  does not have to include the air filter  83 . 
     (2-6) Control Subsystem 
     As illustrated in  FIG. 4 , the main controller  40  is connected to the plurality of fan controllers  34  and the heat source controller  56 . The heat source controller  56  is configured, for example, by various circuits provided on a printed circuit board connected to various equipment in the heat source unit  50 , and controls the various equipment in the heat source unit  50  such as the compressor  51 , the expansion valve  53 , the four-way valve  54 , and the heat source side fan  55 . Also, the main controller  40  is connected to each remote controller  60  through each fan controller  34 . The remote controllers  60   a  to  60   d  correspond to the outlet units  70   a  to  70   d , and are connected to the fan units  30   a  to  30   d . Here, a case where the remote controller  60  is connected to the main controller  40  through the fan controller  34  is described, but the remote controller  60  may also be connected to the main controller  40  directly. Here, a case where the main controller  40 , the plurality of fan controllers  34 , the heat source controller  56 , and the plurality of remote controllers  60  are connected in a wired manner is illustrated, but some or all of the controllers may also be connected by wireless communication. 
     The main controller  40 , the plurality of fan controllers  34 , the heat source controller  56 , and the plurality of remote controllers  60  are achieved by a computer, for example. The computer forming the main controller  40 , the plurality of fan controllers  34 , the heat source controller  56 , and the plurality of remote controllers  60  is provided with a control computing device and a storage device. A processor such as a CPU or a GPU can be used as the control computing device. The control computing device reads a program stored in the storage device and performs predetermined image processing and arithmetic processing in accordance with the program. Further, the control computing device can write an arithmetic result to the storage device and read information stored in the storage device in accordance with the program. However, the main controller  40 , the plurality of fan controllers  34 , the heat source controller  56 , and the plurality of remote controllers  60  may also be configured using an integrated circuit (IC) capable of performing control similar to the control performed using a CPU and memory. Examples of the IC mentioned herein include a large-scale integrated circuit (LSI), an application-specific integrated circuit (ASIC), a gate array, a field programmable gate array (FPGA), and the like. 
     An intake temperature sensor  101 , a gas-side temperature sensor  102 , a liquid-side temperature sensor  103 , and a use side heat exchanger temperature sensor  104  are disposed in the heat exchanger unit  10 . Note that a thermistor for example can be used as the above temperature sensors or a temperature sensor described later. The intake temperature sensor  101 , the gas-side temperature sensor  102 , the liquid-side temperature sensor  103 , and the use side heat exchanger temperature sensor  104  are connected to the main controller  40 , and detection results from the sensors are transmitted to the main controller  40 . The intake temperature sensor  101  detects the temperature of air suctioned from the air inflow port  12   a . The gas-side temperature sensor  102  detects the temperature of the refrigerant at one of the ports of the use side heat exchanger  11  connected to the in-unit refrigerant pipe  132 . The liquid-side temperature sensor  103  detects the temperature of the refrigerant at the other port of the use side heat exchanger  11  connected to the in-unit refrigerant pipe  131 . The use side heat exchanger temperature sensor  104  is attached near-midway in the refrigerant flow path inside the use side heat exchanger  11 , and detects the heat exchanger temperature in a gas-liquid two-phase state flowing through the use side heat exchanger  11 . The main controller  40  uses a detected value from at least one of the intake temperature sensor  101 , the gas-side temperature sensor  102 , the liquid-side temperature sensor  103 , and the use side heat exchanger temperature sensor  104  to determine the instruction related to increasing or decreasing the air supply amount. 
     A heat source side air temperature sensor  111 , a discharge pipe temperature sensor  112 , and a heat source side heat exchanger temperature sensor  113  are disposed in the heat source unit  50 . The heat source side air temperature sensor  111 , the discharge pipe temperature sensor  112 , and the heat source side heat exchanger temperature sensor  113  are connected to the heat source controller  56 . Detection results from the heat source side air temperature sensor  111 , the discharge pipe temperature sensor  112 , and the heat source side heat exchanger temperature sensor  113  are transmitted to the main controller  40  through the heat source controller  56 . The heat source side air temperature sensor  111  detects the temperature of the air flow before passing through the heat source side heat exchanger  52  produced by the heat source side fan  55 . The discharge pipe temperature sensor  112  is configured to detect the temperature of the refrigerant to be discharged from the compressor  51 . The heat source side heat exchanger temperature sensor  113  is attached near-midway in the refrigerant flow path inside the heat source side heat exchanger  52 , and detects the heat exchanger temperature in a gas-liquid two-phase state flowing through the heat source side heat exchanger  52 . 
     A differential pressure sensor  121  and a blow-out temperature sensor  122  are disposed in the fan unit  30 . The differential pressure sensor  121  detects the differential pressure in the air flow between the upstream and downstream sides of the installation location of the fan unit  30 , for example. The differential pressure sensor  121  is connected to the fan controller  34  and transmits detected differential pressure data to the fan controller  34 . For example, the flow path of the spot where the differential pressure sensor  121  is installed has a predetermined cross-sectional area, and the fan controller  34  can calculate the air supply amount from a value detected by the differential pressure sensor  121 . In addition, the fan controller  34  can detect the wind direction from the difference in pressure detected by the differential pressure sensor  121 . The blow-out temperature sensor  122  is disposed in the casing  31  of each fan unit  30 , for example, and detects the temperature of the conditioned air blown out from each fan unit  30 . Here, a case where the blow-out temperature sensor  122  is disposed in the casing  31  of the fan unit  30  is described, but the installation location of the blow-out temperature sensor  122  may also be another location, and may be an installation location inside the outlet unit  70 , for example. 
     Each of the plurality of remote controllers  60  includes a built-in indoor temperature sensor  61 , and is configured to input an instruction for turning the operation of the air conditioning system  1  and/or the fan unit  30  on/off, switching between cooling and heating, inputting a set temperature, and inputting a set air flow volume. The set temperature is configured to be inputtable as a numerical value, for example, and the set air flow volume is configured to be inputtable by selecting one from among very low, low, medium, and high ventilation settings. For example, the user uses an input button on the remote controller  60  to select the cooling operation, set the set temperature to 28° C., and select medium ventilation as the set air flow volume. 
     The main controller  40  calculates the necessary air supply amount to be blown out from each fan unit  30  from the blow-out temperature detected by each blow-out temperature sensor  122  and the set temperature, and controls the rotation speed of the fan motor  33  to bring the detected value from the indoor temperature sensor  61  close to the set temperature. Note that although a case where the indoor temperature sensor  61  is built into the remote controller  60  is described herein, the position where the indoor temperature sensor  61  is provided is not limited to the remote controller  60 . For example, an indoor temperature sensor may exist as an independent device, and the main controller  40  may be configured to receive the value of the indoor temperature from the independent indoor temperature sensor. 
     For example, consider the case where initially three fan units  30  are connected to the heat exchanger unit  10  and one of the air outflow ports  12   b  of the heat exchanger unit  10  is blocked. In such a case, when adding an additional fan unit  30 , a duct  20  is connected to the blocked air outflow port  12   b , the additional fan unit  30  is connected to the duct  20 , and the outlet unit  70  is connected to the added fan unit  30 . If the fan controller  34  of the fan unit  30  added in this way is connected to the main controller  40 , a network of the main controller  40  and four fan controllers  34  is formed, and a network that delivers instructions from the main controller  40  can be constructed easily. 
     (3) Operations by Air Conditioning System  1   
     In the air conditioning system  1 , the set air flow volumes inputted from the plurality of remote controllers  60  act as a basic air supply amount used to determine the air supply amounts of the plurality of fan units  30 . However, if the set air flow volume is left unchanged, the set temperature will fall in the cooling operation and rise in the heating operation after the set temperature is achieved. Accordingly, to cause the indoor air temperature to converge on the set temperature, the air supply amount of each fan unit  30  is changed from the set air flow volume by a command from the main controller  40 . The main controller  40  calculates an air conditioning load from the temperature difference between the indoor air temperature and the set temperature, and determines the necessary air supply amount from the air conditioning load and the fan temperature of each fan unit  30 . For example, in the case where the indoor air temperature matches the set temperature and there is no temperature difference, the air conditioning load is 0, and therefore the main controller  40  stops the fan in each fan unit  30  where the indoor air temperature matches the set temperature, even if the set air flow volume is not 0. However, to avoid the backflow of air from the air outlet  71  toward the heat exchanger unit  10 , each fan unit  30  determined to be stopped according to the air conditioning load may be controlled such that the air supply amount is not 0 in order to suppress backflow. 
     (3-1) Startup 
     Each fan controller  34  of the fan units  30   a  to  30   d  transmits the air supply amount that each of the fan units  30   a  to  30   d  is to supply from the set air flow volume of the four remote controllers  60  to the main controller  40 . Note that when even a stopped fan unit  30  is operating to send an extremely low amount of air to avoid the backflow of air from the air outlet  71  toward the heat exchanger unit  10 , the air conditioning system  1  may be configured to include the slight air supply amount in the total air flow volume. Alternatively, the air conditioning system  1  may be configured not to include the slight air supply amount in the total air flow volume. 
     The main controller  40  totals the air supply amounts transmitted from all of the fan units  30  to calculate the total air flow volume to be passed through the use side heat exchanger  11 . The main controller  40  calculates the temperature of air suctioned into the heat exchanger unit  10  from the intake temperature sensor  101  of the heat exchanger unit  10 . Additionally, the main controller  40  requests the heat source controller  56  of the heat source unit  50  for a required refrigerant circulation rate calculated from the total air flow volume and the air temperature of the air to be passed through the use side heat exchanger  11 . In response to the request from the main controller  40 , the heat source controller  56  of the heat source unit  50  changes the operating frequency of the compressor  51  to change the refrigerant circulation rate. 
     (3-2) Normal Operation 
     In the normal operation, the air conditioning system  1  varies the control between the case where the total air flow volume is at or above a lower limit and the case where the total air flow volume is below the lower limit. 
     (3-2-1) when Total Air Flow Volume is at or Above Lower Limit 
     When a predetermined length of time has elapsed since startup and a normal operating state is reached, the main controller  40  determines whether or not the total air flow volume is at or above the lower limit. The setting of the lower limit will be described later. If the total air flow volume is at or above the lower limit, the main controller  40  controls the air conditioning system  1  according to the following procedure. 
     When a predetermined length of time has elapsed since startup and the normal operating state is reached, each fan controller  34  is configured to recalculate the individual air supply amount on a predetermined interval. In the recalculation, each fan controller  34  uses the indoor air temperature detected by the remote controller  60  for example to calculate an air conditioning load on the basis of a status such as the indoor air temperature near each outlet unit  70  “approaching” or “diverging from” the set temperature, and corrects the set air flow volume. Additionally, each fan unit  30  transmits the corrected air supply amount to the main controller  40 . Note that the main controller  40  may also be configured to perform the calculations related to correcting the set air flow volume. The main controller  40  recalculates the air supply amounts transmitted from the plurality of fan controllers  34  at each interval to calculate the total air flow volume, and if the total air flow volume is at or above the lower limit, the main controller  40  requests the heat source controller  56  of the heat source unit  50  for the required refrigerant circulation rate calculated from the total air flow volume and the air temperature of the air to be passed through the use side heat exchanger  11  at each interval. In response to the request from the main controller  40 , the heat source controller  56  of the heat source unit  50  changes the operating frequency of the compressor  51  to change the refrigerant circulation rate. 
     (3-2-2) when Total Air Flow Volume is Below Lower Limit 
     When the total air flow volume is below the lower limit, the main controller  40  calculates the shortage, that is, the difference between the calculated total air flow volume and the lower limit. The main controller  40  assigns the shortage to the plurality of fan units  30  according to a predetermined air flow volume distribution rule. When assigning the shortage to the plurality of fan units  30 , because it is sufficient for the total air flow volume to be at or above the lower limit, an air supply amount that matches the shortage is assigned in some cases, and an air supply amount greater than or equal to the shortage is assigned in other cases. 
     For example, consider the case where the lower limit is 30 m 3 /min, the fan controller  34  of the fan unit  30   a  requests 16 m 3 /min, the fan controller  34  of the fan unit  30   b  requests 0 m 3 /min, the fan controller  34  of the fan unit  30   c  requests 10 m 3 /min, and the fan controller  34  of the fan unit  30   d  requests 6 m 3 /min to the main controller  40 . In this case, the total air flow volume calculated by the main controller  40  is 32 m 3 /min&gt;30 m 3 /min, and the main controller  40  determines that the total air flow volume is above the lower limit. 
     Next, if an instruction to stop sending air is inputted from the remote controller  60  into the fan controller  34  of the fan unit  30   c , the request from the fan controller  34  of the fan unit  30   c  is changed from 10 m 3 /min to 0 m 3 /min. Consequently, the total air flow volume falls from 32 m 3 /min to 22 m 3 /min, and therefore the main controller  40  determines that an instruction that would bring the total air flow volume at or below the lower limit has been issued. 
     As one example, in the case of determining that a change that would bring the total air flow volume at or below the lower limit has been instructed, the main controller  40  distributes the shortage equally among the operating fan units  30 . In the case described above, 8 (=30-22) m 3 /min is distributed as 4 m 3 /min to the fan unit  30   a  and 4 m 3 /min to the fan unit  30   b , so that the fan unit  30   a  is changed to 20 m 3 /min and the fan unit  30   d  is changed to 10 m 3 /min. 
     As another example, in the case of determining that a change that would bring the total air flow volume at or below the lower limit has been instructed, the main controller  40  distributes the shortage equally among all of the fan units  30 . In the case described above, 8 (=30-22) m 3 /min is distributed as 2 m 3 /min each to the fan units  30   a  to  30   d , such that the fan unit  30   a  is changed to 18 m 3 /min, the fan unit  30   b  is changed to 2 m 3 /min, the fan unit  30   b  is changed to 2 m 3 /min, and the fan unit  30   d  is changed to 8 m 3 /min. 
     (3-2-3) Setting the Lower Limit 
     The main controller  40  determines the lower limit of the total air flow volume of the air conditioning system  1  on the basis of the heat exchanger temperature, for example. For example, if the heat exchanger temperature is high in the cooling operation, the capacity of the heat source unit  50  to supply heating energy is determined to be insufficient, and a high lower limit of the total air flow volume is set. If the heat exchanger temperature is low in the cooling operation compared to such a case, the capacity of the heat source unit  50  to supply heating energy is determined to be more than sufficient, and a lower limit of the total air flow volume that is lower than the above case is set. The specific value of the lower limit is determined by experiment using the actual equipment of the air conditioning system  1  and/or by simulation. 
     (3-2-4) Detection of Air Backflow 
     For example, in the distribution flow path including the duct  20   a , the fan unit  30   a , and the outlet unit  70   a , an air flow proceeding from the heat exchanger unit  10  to the air outlet  71  is a normal air flow, but conversely, an air flow proceeding from the air outlet  71  to the heat exchanger unit  10  is an abnormal air flow that acts as air backflow. The same applies to the distribution flow paths including the ducts  20   b  to  20   d , the fan units  30   b  to  30   d , and the outlet units  70   b  to  70   d , and air flows proceeding from the air outlets  71  to the heat exchanger unit  10  act as air backflow. The differential pressure sensor  121  respectively provided in each of the fan units  30   a  to  30   d  transmits detection results to the main controller  40  through the fan controllers  34 . 
     The main controller  40  determines that the air flow is normal when the air pressure at the exhaust port  37  is lower than or equal to the air pressure at the intake port  36  of the fan units  30   a  to  30   d , and conversely determines that air backflow is occurring when the air pressure at the exhaust port  37  is higher than the air pressure at the intake port  36  of the fan units  30   a  to  30   d.    
     (3-2-5) Operation when Air Backflow Occurs 
     The main controller  40  clears air backflow through the cooperation of the fan units  30 . Specifically, the main controller  40  detects a fan unit  30  connected to a distribution flow path where air backflow is occurring. The main controller  40  transmits a command to increase the rotation speed of the fan motor  33  to the fan controller  34  of the fan unit  30  on the distribution flow path where air backflow is occurring. For example, in the case where the fan motor  33  has stopped, a command to start driving at a predetermined rotation speed is transmitted. As another example, in the case where the fan motor  33  is rotating at a low speed, a command to raise the rotation speed of the fan motor  33  further is transmitted. 
     Note that if the air resistance can be changed with the air deflector  74 , the air deflector  74  may also be used to clear the air backflow. For example, in the case where the fan motor  33  has stopped, the air deflector  74  of the outlet unit  70  where air backflow is occurring may be configured to be fully closed. In the case where the fan motor  33  is rotating at a low speed, the main controller  40  may be configured to transmit a command for raising the rotation speed of the fan motor  33  and also increasing the air resistance of the air deflector  74 . 
     Additionally, a configuration may also be adopted in which a backflow prevention damper that is fully closed just by the force of a backflow air current is provided in the distribution flow path. In this case, backflow can be prevented without a command from the main controller  40 . 
     (4) Modifications 
     (4-1) Modification 1A 
     The first embodiment above describes a case where the ducts  20  are directly connected to the heat exchanger unit  10 , but the ducts  20  may also be indirectly connected to the heat exchanger unit  10 . For example, a configuration is possible in which an attachment having a plurality of air outlets for connecting the ducts  20  to the heat exchanger unit  10  is installed between the ducts  20  and the heat exchanger unit  10 . By preparing multiple types of attachments connectible to different numbers of ducts  20 , the number of ducts  20  that can be connected to the same type of heat exchanger unit  10  can be changed. 
     (4-2) Modification 1B 
     The first embodiment above describes a case where a single outlet unit  70  is connected to a single fan unit  30 , but a configuration in which a plurality of outlet units  70  are connected to a single fan unit  30  is also possible. That is to say, a plurality of air outlets  71  may be provided with respect to a single fan unit  30 . In this case, a plurality of remote controllers  60  may also be connected to each fan unit  30 , such as by providing one remote controller  60  for each outlet unit  70 . 
     (4-3) Modification 1C 
     The first embodiment above describes a case where a vent  79  is provided and only a single inlet  81  is provided in the wall between the rooms RA 1  and RA 2 . However, the number of inlets  81  to be provided is not limited to one and may also be a plurality. Also, the inlet  81  may be provided plurally in the same room RA 1 , or in both of the different rooms RA 1  and RA 2 , for example. In the case of providing the inlet  81  in each of the rooms RA 1  and RA 2 , the vent  79  does not have to be provided. 
     (4-4) Modification 1D 
     Another duct  20  and another fan unit  30  may also be connected to the fan unit  30  connected to the other end  22  of a duct  20  whose one end  21  is connected to the heat exchanger unit  10 . 
     For example, a plurality of fan units  30  may be connected in series with respect to a single distribution flow path. As one example of such a connection configuration, two ducts  20 , two fan units  30 , and one outlet unit  70  may be connected in series from the heat exchanger unit  10  in the order of a duct  20 , a fan unit  30 , a duct  20 , a fan unit  30 , and the outlet unit  70 . By providing a plurality of power sources in a single distribution flow path, it is possible to set a longer distance from the heat exchanger unit  10  to the air outlet  71  compared to the case of providing just one of the same power source. 
     (4-5) Modification 1E 
     The first embodiment above describes a case where a single heat exchanger unit  10  is connected to a single heat source unit  50 , but the connection configuration between the heat source unit  50  and the heat exchanger unit  10  is not limited thereto. For example, a plurality of heat exchanger units  10  may also be connected to a single heat source unit  50 . Also, a plurality of heat source units  50  may be connected to a plurality of heat exchanger units  10 . In these connection configurations, a flow rate adjustment device that adjusts the flow rate of the refrigerant flowing through the use side heat exchanger  11  may also be provided in the heat exchanger units  10 . A flow control valve with a variable opening degree may be used as such a flow rate adjustment device. 
     (4-6) Modification 1F 
     The first embodiment above describes a case where the compressor  51  of the heat source unit  50  is a type having a variable rotation speed. However, a type of compressor  51  that does not have a variable rotation speed may also be used in the heat source unit  50 . 
     (4-7) Modification 1G 
     The first embodiment above describes a case where the air conditioning system  1  is configured to be switched between the cooling operation and the heating operation. However, the technical concept of the first embodiment above can be applied to an air conditioning system that is dedicated to cooling only or heating only. 
     (4-8) Modification 1H 
     The first embodiment above describes a case where the heat exchanger unit  10  is connected to the heat source unit  50  to form a refrigeration cycle apparatus that runs a refrigerant through the use side heat exchanger  11 , but the heat source unit  50  is not limited to the case of connecting the heat exchanger unit  10  to form a refrigeration cycle apparatus. A heat source unit that supplies heating energy to the use side heat exchanger  11  may also be configured to supply a heat medium such as heated water and/or cooled water, for example. 
     In the case of a configuration that runs a heat medium to the use side heat exchanger  11  in this way, a flow rate adjustment device for adjusting the flow rate of the heat medium flowing to the use side heat exchanger  11  may also be provided in the heat exchanger unit  10 . 
     Also, in the case of connecting the heat exchanger unit  10  to such a heat source unit that supplies a heat medium, a plurality of heat exchanger units  10  may also be connected to a single heat source unit. 
     (4-9) Modification 1I 
     The first embodiment above describes a case where, during startup, the main controller  40  requests the refrigerant circulation rate required by the refrigerant circuit  200  as calculated from the calculated total air flow volume of the air passing through the use side heat exchanger  11  and the calculated air temperature of the air suctioned into the heat exchanger unit  10 . However, the method by which the main controller  40  determines the required refrigerant circulation rate to be requested is not limited to the method described above. For example, the air conditioning system  1  may also be configured as follows. 
     During startup, the main controller  40  totals the air supply amounts transmitted from all of the fan units  30 , and calculates the total air flow volume passing through the use side heat exchanger  11 . The main controller  40  stores an air flow volume table indicating relationships between the total air flow volume and the required refrigerant circulation rate in an internal memory, for example. The main controller  40  selects the air flow volume closest to the calculated total air flow volume from among the air flow volumes described in the air flow volume table. The main controller  40  requests the heat source controller  56  for a refrigerant circulation rate corresponding to the total air flow volume selected from the air flow volume table. Additionally, with regard to the difference between the air flow volume selected from the air flow volume table and the total air flow volume, the air conditioning system  1  may be configured to output a command from the main controller  40  to the fan controllers  34  and thereby cause the plurality of fan units  30  to change the air supply amount in accordance with the difference. 
     As another example, the air conditioning system  1  may also be configured as follows. During startup, the main controller  40  receives the set temperature from the remote controller  60  through the fan controller  34 . Also, the main controller  40  receives the indoor air temperature detected by the remote controller  60 , the indoor air temperature calculated from a value detected by the intake temperature sensor  101 , or the indoor air temperature from an indoor temperature sensor capable of transmitting the indoor air temperature to the main controller  40 . The main controller  40  calculates the overall air conditioning load on the air conditioning system  1  from the received set temperature and indoor air temperature. The main controller  40  calculates the total air flow volume and the required refrigerant circulation rate from the calculated air conditioning load. The main controller  40  calculates the individual air supply amount of each fan unit  30  by multiplying the total air flow volume by the proportion of the air conditioning load on each fan unit  30 , and outputs commands to the plurality of fan controllers  34 . The air conditioning system  1  may be configured such that each fan controller  34  adjusts itself to match the individual air supply amount indicated by the main controller  40 . 
     (4-10) Modification 1J 
     In the air conditioning system  1  according to the first embodiment above, a case is described in which the main controller  40  mainly determines the total air flow volume and controls a condition related to the refrigerant in the heat source unit  50  to obey the determined total air flow volume. Conversely, however, the air conditioning system  1  may also be configured to mainly determine a condition related to the refrigerant in the heat source unit  50 , and determine the total air flow volume to obey the condition. 
     For example, the air conditioning system  1  may also be configured such that the heat source controller  56  controls the operating frequency of the compressor  51  and/or the opening degree of the expansion valve  53 . In the air conditioning system  1  configured in this way, the heat source controller  56  ascertains information related to the total air flow volume of the air currently passing through the use side heat exchanger  11 . From information related to the operating frequency of the compressor  51  and/or the opening degree of the expansion valve  53 , the heat source controller  56  transmits an instruction to the main controller  40  indicating a need to increase or decrease the air flow volume with respect to the current total air flow volume. The main controller  40  receives the instruction to increase or decrease the air flow volume from the heat source controller  56 , calculates what proportional increase or decrease of the air flow volume in each fan unit  30  is suitable for reducing the energy of the system as a whole, and outputs instructions to the plurality of fan units  30 . 
     (4-11) Modification 1K 
     The air conditioning system  1  according to the first embodiment above adjusts the refrigerant circulation rate of the refrigerant circuit  200  by changing the operating frequency of the compressor  51 . However, the control of the refrigerant circulation rate in the air conditioning system  1  is not limited to controlling the operating frequency of the compressor  51 . For example, the adjustment of the refrigerant circulation rate of the refrigerant circuit  200  may be controlled by adjusting the operating frequency of the compressor  51  while also adjusting the opening degree of the expansion valve  53 , or the adjustment of the refrigerant circulation rate of the refrigerant circuit  200  may be controlled by adjusting the opening degree of the expansion valve  53 . 
     (4-12) Modification 1 
     In the first embodiment above, the lower limit of the total air flow volume is determined according to the heat exchanger temperature of the use side heat exchanger  11 , but the condensation temperature (TC), the evaporation temperature (TE), or the degree of superheating (SH) and the degree of subcooling (SC) may also be used. The degree of superheating can be calculated by using the inlet temperature and the outlet temperature of the use side heat exchanger  11  or by using the inlet pressure and outlet temperature of the use side heat exchanger  11 , for example. The degree of subcooling can be calculated by using the inlet temperature and the outlet temperature of the use side heat exchanger  11  or by using the inlet pressure and outlet temperature of the use side heat exchanger  11 , for example. 
     The lower limit of the total air flow volume may be a predetermined fixed value, and if the lower limit is set to 8 m 3 /min in advance, the main controller  40  continuously controls the air flow volume to keep from dropping below the lower limit of 8 m 3 /min, for example. 
     In addition, the air conditioning system  1  may also be configured such that in the cooling operation, the lower limit of the total air flow volume is determined according to the degree of superheating, the current total air flow volume, and the intake temperature of the air suctioned into the heat exchanger unit  10 , for example. The air conditioning system  1  may also be configured such that in the heating operation, the lower limit of the total air flow volume is determined according to the degree of subcooling, the current total air flow volume, and the intake temperature of the air suctioned into the heat exchanger unit  10 . The air conditioning system  1  may also be configured such that the lower limit of the total air flow volume is determined according to the refrigerant circulation rate (for example, the operating frequency of the compressor  51 ), the evaporation temperature (TE), and the intake air temperature and intake air flow volume of the air suctioned into the heat exchanger unit  10 . The air conditioning system  1  may also be configured such that the lower limit of the total air flow volume is determined according to an excess or insufficient air flow volume calculated from the dry or wet quality of the refrigerant after passing through the use side heat exchanger  11 , and the current air flow volume. Furthermore, the air conditioning system  1  may also be configured such that the lower limit of the total air flow volume is determined according to the refrigerant pressure and refrigerant temperature at the outlet of the use side heat exchanger  11 . 
     (4-13) Modification 1M 
     (4-13-1) 
     The first embodiment is described by taking the fan motors  33  having a variable rotation speed as an example of a plurality of actuators configured to change the individual air supply amounts of the conditioned air suctioned from the heat exchanger unit  10  through the plurality of ducts  20  and supplied to the plurality of air outlets  71  in the air conditioned space SA. However, the actuators are not limited to the fan motors  33 , and the driving motor  39  of the damper  38  illustrated in  FIG. 5  may also be used as the plurality of actuators, for example. The fan motor  33  of the fan  32  illustrated in  FIG. 5  may be a type of motor having a variable rotation speed similar to the first embodiment, or a type of motor that does not have a variable rotation speed. In the case where the fan motor  33  is a type that does not have a variable rotation speed, the air supply amount (air flow volume) from the fan unit  30  to the outlet unit  70  is changed with the damper  38  alone. In contrast, if the fan motor  33  is a type with a variable rotation speed, the air supply amount (air flow volume) from the fan unit  30  to the outlet unit  70  is changed by changing not only the opening degree of the damper  38  but also the rotation speed of the fan motor  33 . 
     Also, a damper unit that includes the damper  38  but does not include a fan may be used as a unit for changing the individual air supply amounts of the conditioned air to be supplied to the air outlets  71 . In other words, the air conditioning system  1  may also be configured to include a fan unit that simply causes a fan to rotate at a constant speed and does not have a function of changing the air supply amount, and a damper unit separate from the fan unit, for example. For example, the air conditioning system  1  may be configured such that a damper unit configured to change the air supply amount with the damper  38  is provided partway in at least one of the ducts  20   a  to  20   d . Additionally, the air conditioning system  1  may also be configured such that the fan unit  30  having a function of changing the air supply amount and a damper unit having a function of changing the air supply amount are disposed together in at least one of the ducts  20   a  to  20   d.    
     (4-13-2) Operations when Backflow Occurs 
     The main controller  40  clears air backflow through the cooperation of the fan units  30 . To clear air backflow, first, the main controller  40  detects the fan unit  30  connected to the distribution flow path where the air backflow is occurring. In the case where the fan unit  30  is configured to adjust the air supply amount with the damper  38  alone, the main controller  40  transmits a command for changing the opening degree of the damper  38  to the fan controller  34  of the fan unit  30  in the distribution flow path where the air backflow is occurring. For example, in the case that the fan unit  30  where the air backflow is occurring is not running, a command to fully close the damper  38  is transmitted. Normally air backflow does not occur when sending air according to the opening degree of the damper  38  while causing the fan motor  33  to rotate at a constant speed, and therefore if air backflow occurs in such a case, the main controller  40  uses the remote controller  60  to notify the user of an abnormal state, for example. 
     In the case where the fan unit  30  is configured to adjust the air supply amount with both the rotation speed of the fan motor  33  and the opening degree of the damper  38 , the main controller  40  transmits a command for changing the rotation speed of the fan motor  33  and/or the opening degree of the damper  38  to the fan controller  34  of the fan unit  30  in the distribution flow path where the air backflow is occurring. For example, in the case that the fan unit  30  where the air backflow is occurring is not running, a command to fully close the damper  38  is transmitted. As another example, in the case where the fan motor  33  is rotating at a low speed, a command to raise the rotation speed further is transmitted. Alternatively, in the case where the fan motor  33  is rotating at a low speed, the main controller  40  may be configured to transmit a command for reducing the opening degree of the damper  38  and also raising the rotation speed of the fan motor  33 , for example. 
     (4-14) Modification 1N 
     The first embodiment above describes a case wherein the differential pressure sensor  121  is used as a detection device that detects air backflow, but the device that detects air backflow is not limited to a device using the differential pressure sensor  121 . A directional wind speed sensor may also be used as such a detection device. In the case of using a directional wind speed sensor instead of the differential pressure sensor  121 , the wind speed sensor is disposed in the fan unit  30  and connected to the fan controller  34 , for example. In the case of using a directional wind speed sensor, the main controller  40  is capable of detecting that air is flowing in the normal direction when the sensor indicates a wind speed in the positive direction, and conversely detecting that air backflow is occurring in the case where the sensor indicates a wind speed in the negative direction. Additionally, the detection device may also be configured using a plurality of nondirectional wind speed sensors. If a plurality of nondirectional wind speed sensors is used to detect a wind speed distribution, and the wind speed distribution is a distribution that occurs when backflow exists, the main controller  40  may determine that backflow is occurring. 
     (4-15) Modification 1O 
     In the first embodiment, the description is given of the case where the plurality of fan controllers  34  of the plurality of fan units  30  are directly connected in parallel to the main controller  40  installed in the heat exchanger unit  10 . However, the plurality of fan units  30  may be classified into a master unit and a slave unit, and the fan controller  34  may be connected to the main controller  40 . 
     For example, in a case where five fan units  30 M and  30 S are connected to one heat exchanger unit  10 , as shown in  FIG. 6 , the five fan units are classified into one fan unit  30 M as the master unit and the four fan units  30 S as the slave units. The five fan units  30 M and  30 S have the same configuration as that of the fan unit  30  described above. The main controller  40  of the heat exchanger unit  10  is connected to the heat source controller  56  of the heat source unit  50  and the one fan unit  30 M as the master unit. Further, the fan controller  34  of the one fan unit  30 M as the master unit is connected to the fan controllers  34  of the four fan units  30 S as the slave units. The main controller  40  manages the fan controllers  34  of the four fan units  30 S as the slave units through the fan controller  34  of the fan unit  30 M as the master unit. The main controller  40  may directly give a command to the fan controllers  34  of the four slave units, or the fan controller  34  of the fan unit  30 M as the master unit may give a command in response to the command from the main controller  40 . 
     (4-16) Modification 1P 
     In the first embodiment and the modification 10, the main controller  40  is installed in the heat exchanger unit  10 , however, the main controller  40  may be installed in the fan unit  30 M as the master unit as shown in  FIG. 7 or 8 . 
     In such a case, the heat exchanger unit  10  is provided with a terminal  19  for connection to various sensors disposed therein. The main controller  40  is connected to a sensor inside the heat exchanger unit  10  through the terminal  19  of the heat exchanger unit  10 . As shown in  FIG. 7 , the heat source controller  56  of the heat source unit  50  is connected to the main controller  40  of the fan unit  30 M through the heat exchanger unit  10 . Alternatively, as shown in  FIG. 8 , the heat source controller  56  of the heat source unit  50  is directly connected to the main controller  40  of the fan unit  30 M. 
     For example, in a case where the five fan units  30 M,  30 GM, and  30 S are connected to one heat exchanger unit  10 , as shown in  FIG. 7 or 8 , the five fan units are classified into the one fan unit  30 M as the master unit, the two fan units  30 GM as group master units, and the two fan units  30 S as the slave units. Here, the fan controller  34  of the fan unit  30 M as the master unit is only replaced with the main controller  40 , and the configurations of the five fan units  30 M,  30 GM, and  30 S are the same as that of the fan unit  30  described above. The main controller  40  of the fan unit  30 M is connected to the fan units  30 GM as the group master units. Next, the fan controller  34  of the fan unit  30 GM as each of the group master units is connected to the fan controller  34  of the fan unit  30 S as the slave unit of each group. The description herein takes the case where the fan controller  34  of one fan unit  30 S as the slave unit is connected to the fan controller  34  of one fan unit  30 GM as the group master unit; however, the number of fan controllers  34  of the slave units connected to the fan controller  34  of the group master unit is not limited to one, and may be two or more. Further, the number of group master units is not limited to two, and may be one or three or more. Another configuration is possible in which a plurality of fan controllers  34  of the fan units  30 S as the slave units are connected in parallel to the main controller  40  of one fan unit  30 M. 
     The main controller  40  manages the fan controllers  34  of the two fan units  30 GM as the group master units. In addition, the main controller  40  manages the fan controllers  34  of the two fan units  30 S as the group slave units through the fan controllers  34  of the fan units  30 GM as the group master units. The main controller  40  may directly give a command to the fan controllers  34  of the two slave units, or the fan controller  34  of the group master unit may give a command in response to the command from the main controller  40 . 
     (4-17) Modification 1Q 
     In the first embodiment and the modifications 1O to 1P described above, the main controller  40  is installed in the heat exchanger unit  10 ; however, as shown in  FIG. 9, 10, 11 , or  12 , the main controller  40  may be installed in a place other than the heat exchanger unit  10 , the fan unit  30 , and the heat source unit  50 . 
     In such a case, the heat exchanger unit  10  is provided with a terminal  19  for connection to various sensors disposed therein. The main controller  40  is connected to a sensor inside the heat exchanger unit  10  through the terminal  19  of the heat exchanger unit  10 . 
       FIG. 9  is a block diagram showing a configuration in which the main controller  40 , the fan controller  34 , and the heat source controller  56  are connected in a manner similar to those in the first embodiment, and the installation position of the main controller  40  is changed from the heat exchanger unit  10  in the first embodiment to another place. 
       FIG. 10  is a block diagram showing a configuration in which the main controller  40 , the fan controller  34 , and the heat source controller  56  are connected in a manner similar to those in the modification 1O shown in  FIG. 7 , and the installation position of the main controller  40  is changed from the heat exchanger unit  10  in the modification 1O to another place. 
     (4-18) Modification 1R 
     In the modification 1Q, the description takes the case where the plurality of fan controllers  34  of the plurality of fan units  30  are directly connected in parallel to the main controller  40  (see  FIG. 9 ) and the case where the fan controllers  34  of the two fan units  30 GM as the group master units are connected to the fan controller  34  of the one fan unit  30 M as the master unit and the fan controller  34  of the fan unit  30 S as the slave unit is connected to the group master unit (see  FIGS. 10 and 11 ). However, instead of providing the entire master unit, the master units may be classified into group master units and the fan controller  34  may be connected to the main controller  40 . 
     For example, in a case where the five fan units  30 GM and  30 S are connected to one heat exchanger unit  10 , as shown in  FIG. 12 , the five fan units are classified into the three fan units  30 GM as the group master units and the two fan units  30 S as the slave units. The five fan units  30 GM and  30 S have the same configuration as that of the fan unit  30  described above. The main controller  40  of the heat exchanger unit  10  is connected to the heat source controller  56  of the heat source unit  50  and the three fan units  30 GM as the group master units. Next, the fan controllers  34  of the two fan units  30 GM as the group master units are connected to the fan controller  34  of the fan unit  30 S as the slave unit of each group. However, the fan controller  34  as the slave unit is not connected to the fan controller  34  of the one fan unit  30 GM as the group master unit. The description herein takes the case where the fan controller  34  of one fan unit  30 S as the slave unit is connected to the fan controller  34  of one fan unit  30 GM as the group master unit and the case where the fan controller  34  of the slave unit is connected to the fan controller  34  of the one fan unit  30 GM as the group master unit; however, the number of fan controllers  34  of the slave units connected to the fan controller  34  of the group master unit is not limited to one, and may be two or more. 
     The main controller  40  manages the fan controllers  34  of the two fan units  30 S as the group slave units through the fan controllers  34  of the two fan units  30 GM as the group master units. The main controller  40  may directly give a command to the fan controllers  34  of the two slave units, or the fan controller  34  of the group master unit may give a command in response to the command from the main controller  40 . 
     As described above, since the main controller  40  is disposed in a place other than the heat exchanger unit  10  and the plurality of fan units  30 , the installation of the main controller  40  is no longer limited to the heat exchanger unit  10  and the plurality of fan units  30 GM and  30 S, which increases the flexibility of the installation of the main controller  40  and makes it easy to handle the main controller  40 . 
     (4-19) Modification 1S 
     The first embodiment above describes a configuration in which the differential pressure sensor  121  (air flow volume detector) is used to detect the differential pressure inside a predetermined segment, but the configuration that detects the air flow volume is not limited to such a configuration. For example, the configuration that detects the air flow volume may also be configured to use a differential pressure sensor to detect the differential pressure before and after the fan  32  of each fan unit  30 , and the main controller  40  or the fan controller  34  may calculate the air flow volume from the differential pressure characteristics before and after the fan  32 . In this case, the differential pressure sensor also acts as the air flow volume detector. For example, a wind speed sensor may be used to detect the wind speed at a specific position, and the main controller  40  or the fan controller  34  may be configured to calculate the air flow volume from the wind speed characteristics at the specific position. In this case, the wind speed sensor acts as the air flow volume detector. For example, a pressure sensor may be used to detect an internal pressure displacement, and the main controller  40  or the fan controller  34  may be configured to calculate the air flow volume by comparing the internal pressure displacement when a prescribed air flow volume flows to the detected pressure displacement. In this case, the pressure sensor acts as the air flow volume detector. As another example, the main controller  40  or the fan controller  34  may be configured to use the operating current of the fan  32  to calculate the air flow volume from the workload of the fan motor  33 . In this case, a device that detects the operating current acts as the air flow volume detector. 
     (4-20) Modification 1T 
     The first embodiment above describes an example of a case where the main controller  40  calculates the refrigerant circulation rate and transmits a request to change the operating frequency of the compressor  51  to the heat source controller  56 , and the heat source controller  56  controls the operating frequency of the compressor  51 . However, the air conditioning system  1  may also be configured such that the main controller  40  controls the operating frequency of the compressor  51  and/or the opening degree of the expansion valve  53 . 
     (4-21) Modification 1U 
     The first embodiment above describes a case where the plurality of ducts  20   a  to  20   d  are connected to the heat exchanger unit  10 , and the ducts  20   a  to  20   d  respectively extend from the heat exchanger unit  10  to the fan units  30  without branching partway along. However, ducts that branch partway along may also be used in the air conditioning system  1 . For example, the air conditioning system  1  may also be configured such that a fan unit  30  is connected to each branch diverging from a single duct. 
     (5) Characteristics 
     5-1 
     The air conditioning system  1  of the first embodiment includes the controller  300 , the plurality of ducts  20 ,  20   a  to  20   e , and the plurality of fan units  30 ,  30   a  to  30   d ,  30 M,  30 GM, and  30 S. The plurality of ducts  20 ,  20   a  to  20  are used to distribute conditioned air that has passed through the use side heat exchanger  11  of the heat exchanger unit  10 . The plurality of fan units  30 ,  30   a  to  30   d ,  30 M,  30 GM, and  30 S are provided so as to correspond to the plurality of ducts  20 ,  20   a  to  20   e , and supply the conditioned air from the heat exchanger unit  10  through the plurality of ducts  20 ,  20   a  to  20   e  to the air conditioned space SA. The plurality of actuators are configured to change the air supply amount of conditioned air to be supplied to the air conditioned space SA. In the first embodiment, the plurality of actuators are selected from among the plurality of fan motors  33 , the plurality of driving motors  39 , and the plurality of air deflector motors  75 . The plurality of actuators are the plurality of fan motors  33 , the plurality of driving motors  39 , or the plurality of air deflector motors  75  in some cases. In addition, the plurality of actuators may include different types of actuators, for example, both the fan motor  33  and the driving motor  39  at the same time. Each of the plurality of ducts  20 ,  20   a  to  20   e  is disposed in one of the plurality of distribution flow paths. Each of the plurality of fan units  30 ,  30   a  to  30   d ,  30 M,  30 GM, and  30 S includes the fans  32 ,  32   a  to  32   d , which are first fans, and is arranged in one of the plurality of distribution flow paths. Each of the plurality of actuators is disposed in one of the plurality of distribution flow paths. By controlling the plurality of actuators, the controller  300  controls the air supply amount of each of the plurality of fan units  30 ,  30   a  to  30   d ,  30 M,  30 GM, and  30 S. As a result, the air conditioning system  1  according to the first embodiment can adjust the air flow volume passing through the use side heat exchanger  11  such that heat is exchanged efficiently in the use side heat exchanger  11 , and energy consumption can be moderated. 
     (5-2) 
     The main controller  40  of the controller  300  of the first embodiment gives a plurality of instructions concerning the air supply amounts of the plurality of fan units  30  in order to control the number of rotations of the plurality of fan motors  33  which are a plurality of actuators in the plurality of fan units  30 , the driving motors  39  of the plurality of dampers  38 , or the air deflector motor  75  of the air deflector  74 . As a result, the air conditioning system  1  according to the first embodiment can adjust the air flow volume passing through the use side heat exchanger  11  such that heat is exchanged efficiently in the use side heat exchanger  11 , and energy consumption can be moderated. 
     5-3 
     In the air conditioning system  1  according to the first embodiment, since the main controller  40  is disposed in the heat exchanger unit  10 , it is preferable to construct a network connecting the main controller  40  and the fan motors  33 , which are a plurality of actuators, in accordance with the flow of the conditioned air supplied from the heat exchanger unit  10 . Therefore, a network for sending an instruction from the main controller  40  can be easily constructed with the heat exchanger unit  10  as a starting point. 
     5-4 
     In a case where the main controller  40  is disposed in the fan unit  30 M as the master unit which is one of the plurality of fan units  30 , the air conditioning system  1  including one main controller  40  in the plurality of fan units  30  can be formed by connecting the network of the plurality of fan units  30 , which facilitates the construction of the air conditioning system  1 . In other words, since it is only required that at least one fan unit  30 M as the master unit is included in the plurality of fan units  30 , the air conditioning system  1  can be easily designed and constructed. 
     Note that, in a case where a plurality of main controllers  40  are present, the plurality of main controllers  40  may be configured to cooperate and act as one main controller. For example, in a case where an extension is made, the newly added main controller  40  and the main controller  40  existing before the extension can be configured to communicate with each other to function as one new main controller. 
     5-5 
     In a case where the main controller  40  is disposed in a place other than the heat exchanger unit  10  and the plurality of fan units  30 , the installation of the main controller  40  is no longer limited to the heat exchanger unit  10  and the plurality of fan units  30 M,  30 GM and  30 S, which increases the flexibility of the installation of the main controller  40  and makes it easy to handle the main controller  40 . 
     5-6 
     The air conditioning system  1  of the first embodiment is so configured that the airflow passing through the use side heat exchanger  11  is generated only by the air suction force of the plurality of fan units  30 . Therefore, a power source for generating air flow in the heat exchanger unit  10  does not have to be provided, and it is possible to reduce the cost comparing to the case where a power source for generating air flow is provided in the heat exchanger unit  10 . In addition, the heat exchanger unit  10  can be easily made thinner, and the range in which the air conditioning system  1  is installed can be expanded. 
     5-7 
     In a case where the heat exchanger unit  10  includes at least one of the gas-side temperature sensor  102 , the liquid-side temperature sensor  103 , and the use side heat exchanger temperature sensor  104  that are heat medium temperature sensors for detecting the temperature of the refrigerant that is a heat medium flowing through the use side heat exchanger  11  or the pipe connected to the use side heat exchanger  11 , and the intake temperature sensor  101  for detecting the temperature of the air sucked into the heat exchanger unit, and where the main controller  40  uses a detected value of at least one of the heat medium temperature sensor and the suction temperature sensor to determine an instruction concerning the increase or decrease in the air supply amount, the main controller  40  easily gives an instruction to the plurality of fan units  30  to supply air to meet the operating conditions of the heat exchanger unit  10 . For example, in a case where the heat energy supplied from the heat source unit  50  to the heat exchanger unit  10  is insufficient, the main controller  40  reduces the air supply amount on the basis of the detected value of the use side heat exchanger temperature sensor  104 , which reduces a problem such as excessive dropping of the temperature of the refrigerant supplied from the heat source unit  50 . 
     5-8 
     The remote controller  60  of the air conditioning system  1  of the first embodiment has a set temperature function to set temperatures of the rooms RA 1  and RA 2  that are the air conditioned spaces SA and an indoor temperature detection function. The main controller  40  uses the set temperature of the remote controller  60  and the room temperature detected by the remote controller  60  to determine an instruction concerning the increase or decrease in the air supply amount. As a result, the main controller  40  can give an instruction to bring the temperature of the air conditioned space SA closer to the set temperature. In the first embodiment, the remote controller  60  is installed at a plurality of locations in the room RA 1  that is the air conditioned space SA, which makes it easy to bring the indoor air temperature at each of the plurality of locations closer to the set temperature. 
     5-9 
     The air conditioning system  1  of the first embodiment includes the compressor  51  for compressing the refrigerant to be circulated in the use side heat exchanger  11 , the heat source side heat exchanger  52  for transferring heat of the refrigerant circulated in the use side heat exchanger  11 , and the expansion valve  53  for expanding the refrigerant passing between the use side heat exchanger  11  and the heat source heat exchanger  52 . The main controller  40  is connected, through the heat source controller  56 , to the compressor  51  and/or the expansion valve  53  to control the system operation. As a result, it is possible to appropriately control the system operation by controlling the number of rotations of the compressor  51  and/or the opening degree of the expansion valve  53  so as to achieve, for example, a refrigerant circulation rate derived by calculation together with the increase or decrease in the air supply amount, and it is possible to control the increase or decrease in the air supply amount while causing the refrigerant circulating through the use side heat exchanger  11  and the heat source side heat exchanger  52  to perform an appropriate refrigeration cycle. 
     5-10 
     In the air conditioning system  1  of the first embodiment, since the main controller  40  is connected to the compressor  51  and/or the expansion valve  53  for control over the system operation, the main controller  40  can appropriately control the system operation by controlling the number of rotations of the compressor  51  and/or the opening degree of the expansion valve  53  so as to, for example, achieve the refrigerant circulation rate derived by calculation with the increase or decrease in the air supply amount. The main controller  40  can control the increase or decrease in the air supply amount while causing the refrigerant circulating through the use side heat exchanger  11  and the heat source side heat exchanger  52  to perform an appropriate refrigeration cycle. 
     5-11 
     In the air conditioning system  1  of the first embodiment, the main controller  40  controls the fan motor  33  that is an actuator or the damper  38  on the basis of information indicating the number of rotations of the compressor  51  and/or the opening degree of the expansion valve  53  for control over the system operation, therefore, it is possible to control the increase or decrease in the air supply amount while causing the refrigerant circulating through the use side heat exchanger and the heat source side heat exchanger to perform an appropriate refrigeration cycle. 
     5-12 
     The main controller  40  controls air flow volume of air passing through the use side heat exchanger  11  with the plurality of fan motors  33  while adjusting the fan motor  33  that is a plurality of actuators in order to prevent backflow, in the plurality of ducts  20 , of the conditioned air flowing from the heat exchanger unit  10  toward the plurality of air outlets  71 . As a result, it is possible to prevent reduction in heat exchange efficiency due to the backflow of the conditioned air in the plurality of ducts. Further, together with the control described above, the main controller  40  controls the circulation amount of the refrigerant by the number of rotations of the compressor  51  and/or the opening degree of the expansion valve  53 , which makes it easy to moderate the decrease in the heat exchange efficiency. 
     5-13 
     The air conditioning system  1  of the first embodiment includes each damper  38  of each fan unit  30  attached to each duct  20 , and the driving motor  39  (an example of the actuator) for driving each damper  38 . The main controller  40  controls to adjust the opening degrees of the plurality of dampers  38  in order to prevent backflow, in the plurality of ducts  20 , of the conditioned air flowing from the heat exchanger unit  10  toward the plurality of air outlets  71 . As a result, it is possible to easily prevent reduction in heat exchange efficiency due to the backflow of the conditioned air in the plurality of ducts  20 . 
     Alternatively, the air conditioning system  1  includes each air deflector  74  of each outlet unit  70  attached to each duct  20 , and the air deflector motor  75  for driving each air deflector  74 . The main controller  40  controls to adjust the opening degrees of the plurality of air deflectors  74  to prevent backflow, in the plurality of ducts  20 , of the conditioned air flowing from the heat exchanger unit  10  toward the plurality of air outlets  71 . As a result, it is possible to easily prevent reduction in heat exchange efficiency due to the backflow of the conditioned air in the plurality of ducts  20 . 
     5-14 
     The air conditioning system  1  of the first embodiment includes a plurality of fan motors  33  configured to change the air supply amount of each of the plurality of fan units  30 . The air conditioning system  1  controls the backflow of the conditioned air in each duct  20  by adjusting the number of rotations of each fan motor  33 , which makes it easy to prevent reduction in heat exchange efficiency due to the backflow of the conditioned air in each duct  20 . 
     Second Embodiment 
     (6) Overall Configuration 
     The main controller  40  controls a plurality of actuators in accordance with a plurality of instructions concerning the air supply amounts of the plurality of fan units  30 , and such type of control form is not limited to the form of the first embodiment. The air conditioning system  1  in which the main controller  40  controls a plurality of actuators with a plurality of instructions related to the air supply amounts of the plurality of fan units  30  may also be configured like the second embodiment. In the air conditioning system  1  of the second embodiment, the plurality of fan controllers  34 , which are a plurality of sub controllers, receive a plurality of instructions sent by the main controller  40 . In the air conditioning system  1  of the second embodiment, each of the plurality of fan controllers  34  controls at least one of the plurality of actuators on the basis of at least one of the plurality of instructions. 
     Specifically, the air conditioning system  1  according to the second embodiment is described by taking the example of the case of including the configuration illustrated in  FIG. 1 , similarly to the air conditioning system  1  according to the first embodiment. The second embodiment describes the case where the air conditioning system  1  illustrated in  FIG. 1  changes the air supply amount with the fan motor  33 , but the damper  38  and the air deflector  74  are not involved in changing the air supply amount. 
     Like the main controller  40  according to the first embodiment, the main controller  40  according to the second embodiment calculates the necessary air supply amount to be blown out from each fan unit  30  from the blow-out temperature detected by each blow-out temperature sensor  122  and the set temperature. Specifically, for example, the main controller  40  calculates the air supply amount of each of the fan units  30   a  to  30   d  from the temperature difference between the indoor air temperature and the set temperature, and also the fan temperature. The main controller  40  sets the calculated air supply amount (target air supply amount) for each of the fan units  30   a  to  30   d  as an instruction to issue to each of the fan units  30   a  to  30   d.    
     The main controller  40  transmits the plurality of calculated air supply amounts to the plurality of fan controllers  34  as target air supply amounts. In other words, the main controller  40  transmits a plurality of instructions to the plurality of fan controllers  34  that control the fan units  30   a  to  30   d . The main controller  40  transmits the target air supply amount for the fan unit  30   a  to the fan controller  34  installed in the fan unit  30   a , for example. The target air supply amount for the fan unit  30   a  is an instruction related to the air supply amount of the fan unit  30 . The fan controller  34  of the fan unit  30   a  controls the rotation speed of the fan motor  33   a  to cause the air supply amount to approach the target air supply amount. Similarly, the main controller  40  transmits the target air supply amount for the fan units  30   b  to  30   d  to the fan controller  34  installed in the fan units  30   b  to  30   d , for example. The fan controller  34  of the fan units  30   b  to  30   d  controls the fan motors  33   b  to  33   d  to cause the air supply amount to approach the target air supply amount. 
     Described in further detail, each of the fan units  30   a  to  30   d  includes the differential pressure sensor  121  as an air flow volume detector that detects the air flow volume passing through each unit. Note that the air flow volume detector is not limited to the differential pressure sensor  121 . For example, the air flow volume detector may also be a wind speed sensor. For example, the fan controller  34  of the fan unit  30   a  compares the volume of air (air supply amount) passing through the fan unit  30   a  detected by the differential pressure sensor  121  of the fan unit  30   a  with a target air flow volume (target air supply amount). If the air flow volume passing through the fan unit  30   a  is less than the target air flow volume, the fan controller  34  of the fan unit  30   a  increases the rotation speed of the fan motor  33   a  to increase the air flow volume (air supply amount) of the fan unit  30   a  and approach the target air flow volume. Conversely, if the air flow volume passing through the fan unit  30   a  is greater than the target air flow volume, the fan controller  34  of the fan unit  30   a  decreases the rotation speed of the fan motor  33   a  to decrease the air flow volume (air supply amount) of the fan unit  30   a  and approach the target air flow volume. 
     Here, the case where the fan controller  34  is installed in the fan unit  30  is described. However, the fan controller  34  does not have to be installed in the fan unit  30 . 
     (7) Modifications 
     (7-1) Modification 2A 
     In the second embodiment described above, the description is given of the case where the fan motor  33  functions as an actuator for changing the air supply amount. However, the actuator for changing the air supply amount in the second embodiment is not limited to the fan motor  33 . For example, the plurality of actuators may be the driving motor  39  of the damper  38  shown in  FIG. 5 . The fan motor  33  of the fan  32  illustrated in  FIG. 5  may be a type of motor having a variable rotation speed similar to the second embodiment, or a type of motor that does not have a variable rotation speed. In the case where the fan motor  33  is a type that does not have a variable rotation speed, for example, the air supply amount (air flow volume) from the fan unit  30  to the outlet unit  70  is changed with the damper  38  alone. In contrast, if the fan motor  33  is a type with a variable rotation speed, the air supply amount (air flow volume) from the fan unit  30  to the outlet unit  70  is changed by changing not only the opening degree of the damper  38  but also the rotation speed of the fan motor  33 . In such a case, the fan controller  34  may be so configured to control both the driving motor  39  and the fan motor  33  as the actuators. 
     In a case where the fan motor  33  is the motor of a type incapable of changing the number of rotations and the air supply amount (air flow volume) from the fan unit  30  to the outlet unit  70  is changed only by the damper  38 , a damper controller is provided instead of the fan controller  34 . The main controller  40  sends the calculated air supply amount to the plurality of damper controllers as the target air supply amount. The main controller  40  sends, for example, the target air supply amount of the fan units  30   a  to  30   d  to the damper controller attached to the fan units  30   a  to  30   d . The target air supply amount of the fan units  30   a  to  30   d  is an instruction concerning the air supply amount of the fan unit  30 . In other words, the main controller  40  sends a plurality of instructions to the plurality of damper controllers for controlling the fan units  30   a  to  30   d . The damper controller of the fan units  30   a  to  30   d  controls the opening degree of the damper  38  to bring the air supply amount closer to the target air supply amount. 
     More specifically, for example, the damper controller of each of the fan units  30   a  to  30   d  compares volume of air (air supply amount) passing through the fan unit  30   a  detected by the differential pressure sensor  121  of each of the fan units  30   a  to  30   d  with the target air flow volume (target air supply amount). In a case where the volume of the air passing through the fan units  30   a  to  30   d  is smaller than the target air flow volume, the damper controller of each of the fan units  30   a  to  30   d  increases the opening degree of the damper  38  with the driving motor  39  and increases the air flow volume (air supply amount) of the fan units  30   a  to  30   d  to bring the air flow volume closer to the target air flow volume. Conversely, in a case where the volume of the air passing through the fan units  30   a  to  30   d  is greater than the target air flow volume, the opening degree of the damper  38  is reduced by the driving motor  39  and reduces the air flow volume (air supply amount) of the fan units  30   a  to  30   d  to bring the air flow volume closer to the target air flow volume. 
     For example, the plurality of actuators may be the air deflector motor  75 . The fan motor  33  of the fan  32  may be a motor of a type capable of changing the number of rotations similar to that of the second embodiment, or may be a motor of a type incapable of changing the number of rotations. In a case where the fan motor  33  is the motor of a type incapable of changing the number of rotations, the air supply amount (air flow volume) from the fan unit  30  to the outlet unit  70  is changed by both or any one of the damper  38  and the air deflector  74 , for example. On the other hand, in a case where the fan motor  33  is the motor of a type capable of changing the number of rotations, the air supply amount (air flow volume) from the fan unit  30  and the outlet unit  70  to the air conditioned space SA is changed not only with change in the opening degree of both or any one of the damper  38  and the air deflector  74  but with change in the number of rotations of the fan motor  33 . 
     In a case where the fan motor  33  is the motor of a type incapable of changing the number of rotations and the air supply amount (air flow volume) from the fan unit  30  to the outlet unit  70  is changed only by the air deflector  74 , an air deflector controller is provided instead of the fan controller  34 . The main controller  40  sends the calculated air supply amount to the plurality of air deflector controllers as the target air supply amount. The main controller  40  sends, for example, the target air supply amount of the fan units  30   a  to  30   d  to the air deflector controllers attached to the fan units  30   a  to  30   d . The target air supply amount of the fan units  30   a  to  30   d  is an instruction concerning the air supply amount of the fan units  30   a  to  30   d . In other words, the main controller  40  sends a plurality of instructions to the plurality of air deflector controllers for controlling the fan units  30   a  to  30   d . The air deflector controllers of the fan units  30   a  to  30   d  control the opening degree of the air deflector  74  to bring the air supply amount closer to the target air supply amount. 
     More specifically, for example, the air deflector controller of each of the fan units  30   a  to  30   d  compares volume of air (air supply amount) passing through the fan unit  30   a  detected by the differential pressure sensor  121  of each of the fan units  30   a  to  30   d  with the target air flow volume (target air supply amount). In a case where the volume of the air passing through the fan units  30   a  to  30   d  is smaller than the target air flow volume, the air deflector controller of each of the fan units  30   a  to  30   d  increases the opening degree of the air deflector  74  with the air deflector motor  75  and increases the air flow volume (air supply amount) of the fan units  30   a  to  30   d  to bring the air flow volume closer to the target air flow volume. Conversely, in a case where the volume of the air passing through the fan units  30   a  to  30   d  is greater than the target air flow volume, the opening degree of the air deflector  74  is reduced by the air deflector motor  75  and reduces the air flow volume (air supply amount) of the fan units  30   a  to  30   d  to bring the air flow volume closer to the target air flow volume. 
     (8) Characteristics 
     8-1 
     The air conditioning system  1  according to the second embodiment also has the features of the first embodiment described in (5-1). 
     8-2 
     The controller  300  of the second embodiment controls a plurality of actuators in accordance with a plurality of instructions concerning the air supply amounts of the plurality of fan units  30   a  to  30   d . The actuator of the second embodiment is at least one of the fan motor  33 , the driving motor  39 , and the air deflector motor  75 . Such control enables the air conditioning system  1  to adjust the volume of air passing through the use side heat exchanger  11  for efficient heat exchange in the use side heat exchanger  11 , leading to the reduction in energy consumption of the air conditioning system  1 . In the second embodiment, at least one of the plurality of fan controllers  34  of the controller  300 , the plurality of damper controllers, and the plurality of air deflector controllers controls the plurality of actuators. 
     8-3 
     The controller  300  of the air conditioning system  1  of the second embodiment includes the main controller  40  for sending a plurality of instructions and at least one sub-controller for receiving the plurality of instructions from the main controller  40 . Examples of the sub controller of the second embodiment include the fan controller  34 , the damper controller, and the air deflector controller. The at least one sub-controller controls the plurality of actuators on a basis of the plurality of instructions. For example, in a case where the plurality of actuators are only the plurality of fan motors  33 , the fan controllers  34  and the fan motors  33  may be provided in a one-to-one correspondence. Alternatively, the plurality of fan motors  33  may be provided so as to correspond to one fan controller  34 . In such an air conditioning system  1 , since the main controller  40  controls the plurality of actuators through at least one sub controller, the control by the main controller  40  is simplified to facilitate the duct design and the layout change in the system. 
     8-4 
     In the air conditioning system  1  of the second embodiment, each of the plurality of fan units  30   a  to  30   d  includes the differential pressure sensor  121  or a wind speed sensor that is an air flow volume detector for detecting volume of air passing through the unit. Each of the plurality of sub-controllers controls the number of rotations of the fan motors  33   a  to  33   d  in a manner to bring the air flow volume detected by the air flow volume detector closer to the air supply amount instructed by the controller  300 . This allows the controller  300  to reliably control the air supply amounts of the fan units  30   a  to  30   d.    
     8-5 
     In the air conditioning system  1  of the second embodiment, the controller  300  calculates the air supply amount of each of the fan units  30   a  to  30   d  on the basis of the temperature difference between the indoor air temperature to be adjusted by each of the plurality of fan units  30   a  to  30   d  and the set temperature, and determines a plurality of instructions on the basis of the calculated air supply amount. This allows the air conditioning system  1  to easily control the temperature of the air conditioned space SA by changing the air supply amount. 
     Third Embodiment 
     (9) Overall Configuration 
     The air conditioning system  510  illustrated in  FIG. 13  includes a heat exchanger unit  520 , a fan unit  530 , a plurality of ducts  540 , and a controller  550 . The heat exchanger unit  520  includes a second fan  521 . Each of the plurality of fan units  530  includes a first fan  531 . Each first fan  531  supplies air from the fan unit  530  to an air conditioned space SA. The air conditioned space SA is a room inside a building, for example. The room is a space where the movement of air is restricted by a floor, a ceiling, and walls, for example. The plurality of fan units  530  are disposed in the air conditioned space SA including one or more spaces.  FIG. 13  is a diagram showing an example in which, as a representative example of the air conditioning system  510  including the plurality of fan units  530 , the air conditioning system  510  including two fan units  530  is disposed in one air conditioned space SA. The number of fan units  530  may also be three or more, and is set appropriately. As described above, the number of air conditioned spaces SA in which the fan unit  530  is disposed may be two or more. 
     The duct  540  distributes air SAr delivered from the heat exchanger unit  520  by the second fan  521  to the plurality of fan units  530 . The duct  540  includes a main pipe  541  and a branch pipe  542  that branches off from the main pipe  541 . In  FIG. 13 , a case where the main pipe  541  is disposed outside the heat exchanger unit  520  is illustrated, but the main pipe  541  may also be disposed inside the heat exchanger unit  520 , and may also be disposed to extend from the inside of the heat exchanger unit  520  to the outside of the heat exchanger unit  520 . The case where the main pipe  541  is disposed inside the heat exchanger unit  520  also includes the case where a portion of a casing of the heat exchanger unit  520  functions as the main pipe  541 . In  FIG. 13 , an example is illustrated, in which an entrance  541   a  of the main pipe  541  is connected to the heat exchanger unit  520 . The second fan  521  is disposed inside the heat exchanger unit  520 . Here, all of the air blown out from the second fan  521  is configured to flow into the duct  540 . 
     An exit  541   b  of the main pipe  541  of the duct  540  is connected to an entrance  542   a  of the branch pipe  542 . A plurality of exits  542   b  of the branch pipe  542  are connected to the plurality of fan units  530 . 
     Each fan unit  530  and the air conditioned space SA are joined by an air flow passage  581 . An entrance  581   a  of the air flow passage  581  is connected to the fan unit  530 . An exit  581   b  of the air flow passage  581  is connected to the air conditioned space SA. Each first fan  531  produces air flow inside each fan unit  530 , the air flow proceeding from the exits  542   b  of the duct  540  to the entrance  581   a  of the air flow passage  581 . From a different perspective, each first fan  531  is suctioning the air SAr from the exits  542   b  of the branch pipe  542 . Each first fan  531  can change the static pressure inside each fan unit  530  (in front of the entrance  581   a  of the air flow passage  581 ) by changing the rotation speed of each first fan  531  itself. Assuming that the static pressure in the duct  540  is constant, each first fan  531  can increase the rotation speed to thereby raise the static pressure inside each fan unit  530  (in front of the entrance  581   a  of the air flow passage  581 ). If the static pressure inside each fan unit  530  rises, the air quantity of the air SAr flowing through the air flow passage  581  increases. By changing the air quantity in this way, the air supply amount that is blown out from an exit  581   b  of each air flow passage  581  into the air conditioned spaces SA changes. 
     The controller  550  includes a main controller  551  and a plurality of sub-controllers  552 . The main controller  551  and the plurality of sub-controllers  552  are interconnected to form the controller  550 . The main controller  551  controls the rotation speed of the second fan  521 . In other words, the main controller  551  controls the output of the second fan  521 . If the output of the second fan  521  increases, the state of the second fan  521  changes in the direction of increasing air flow volume sent from the second fan  521 . 
     One sub-controller  552  is provided with respect to each fan unit  530 . Each sub-controller  552  outputs an instruction related to changing the air flow volume to a fan motor  531   a  of the corresponding first fan  531 . Each sub-controller  552  stores a target air flow volume (target air supply amount). If the air supply amount is insufficient with respect to the target air flow volume, each sub-controller  552  outputs an instruction (an instruction related to changing the air flow volume) for increasing the rotation speed of the fan motor  531   a  of the first fan  531 . Conversely, if the air supply amount is excessive with respect to the target air flow volume, each sub-controller  552  outputs an instruction (an instruction related to changing the air flow volume) for decreasing the rotation speed of the fan motor  531   a  of the first fan  531 . The instruction related to changing the air flow volume is an instruction related to the air supply amount of the fan unit  530 . 
     The controller  550  obtains information on the air supply amount to be supplied to the air conditioned space SA by the plurality of first fans  531 . The information about the air supply amount indicates the quantity of air to be supplied to the air conditioned space SA per second, for example, and the quantity of air to be supplied may also be referred to as the necessary air supply amount. The controller  550  determines the demand output from the second fan  521  on the basis of the obtained information about the air supply amount. The controller  550  controls the output of the second fan  521  to meet the determined demand output. Specifically, each sub-controller  552  obtains information about the air supply amount of each corresponding fan unit  530  from the fan unit  530 . Each sub-controller  552  outputs the information about the air supply amount to the main controller  551 . 
     (10) Detailed Configuration 
     (10-1) Heat Exchanger Unit  520   
     Besides the second fan  521  already described, the heat exchanger unit  520  includes a use side heat exchanger  522 , a first air flow volume detecting means  523 , a temperature sensor  524 , and a water quantity adjustment valve  525 . The use side heat exchanger  522  is supplied with cold water or hot water for example as a heat medium from the heat source unit  560 . The heat medium supplied to the use side heat exchanger  522  may also be a liquid other than cold water or hot water, such as brine, for example. For the first air flow volume detecting means  523 , an air flow sensor, a wind speed sensor, or a differential pressure sensor may be used, for example. 
     The first air flow volume detecting means  523  detects the air flow volume sent by the second fan  521 . The first air flow volume detecting means  523  is connected to the main controller  551 . The first air flow volume detecting means  523  transmits the value of the air flow volume detected by the first air flow volume detecting means  523  to the main controller  551 . The air flow volume detected by the first air flow volume detecting means  523  is the volume of air flowing through the main pipe  541  of the duct  540 . In other words, the air flow volume detected by the first air flow volume detecting means  523  is the total volume of air supply amount supplied to the air conditioned space SA from the plurality of fan units  530 . 
     The temperature sensor  524  detects the temperature of the air SAr sent from the second fan  521  to the duct  540 . The temperature sensor  524  is connected to the main controller  551 . The temperature sensor  524  transmits the value of the temperature detected by the temperature sensor  524  to the main controller  551 . 
     The heat exchanger unit  520  is joined to the air conditioned space SA through an air flow passage  582 . The air RAr passing through the air flow passage  582  and returning from the air conditioned space SA is sent through the use side heat exchanger  522  to the duct  540  by the second fan  521 . When passing through the use side heat exchanger  522 , the air RAr exchanges heat with the cold water or hot water flowing through the use side heat exchanger  522  to become conditioned air. The water quantity adjustment valve  525  adjusts the amount of heat imparted to the air SAr that exchanges heat in the use side heat exchanger  522  and is sent to the duct  540 . The opening degree of the water quantity adjustment valve  525  is controlled by the main controller  551 . If the opening degree of the water quantity adjustment valve  525  is increased, the amount of water flowing through the use side heat exchanger  522  increases, and more heat is exchanged per unit time between the use side heat exchanger  522  and the air SAr. Conversely, if the opening degree of the water quantity adjustment valve  525  is decreased, the amount of water flowing through the use side heat exchanger  522  decreases, and less heat is exchanged per unit time between the use side heat exchanger  522  and the air SAr. 
     (10-2) Fan Unit  530   
     Besides the first fan  531  already described, each fan unit  530  includes a second air flow volume detecting means  532 . The second air flow volume detecting means  532  detects the air flow volume sent by the first fan  531 . Each second air flow volume detecting means  532  is connected to a corresponding sub-controller  552 . The value of the air flow volume detected by the second air flow volume detecting means  532  is transmitted to the sub-controller  552 . The air flow volume detected by the second air flow volume detecting means  532  is the volume of air flowing through the air flow passage  581 . In other words, the air flow volume detected by the second air flow volume detecting means  532  is the air supply amount supplied to the air conditioned space SA from each fan unit  530 . For the second air flow volume detecting means  532 , an air flow sensor, a wind speed sensor, or a differential pressure sensor may be used, for example. 
     (10-3) Remote Sensor  570   
     A plurality of remote sensors  570  function as temperature sensors. Each remote sensor  570  is configured to transmit data indicating the temperature of the air conditioned space SA to a corresponding sub-controller  552 . 
     (11) Operations by Air Conditioning System  510   
     Each of the plurality of sub-controllers  552  receives a detected value of the temperature of the target space from the respectively connected remote sensor  570 . Each sub-controller  552  stores data indicating a set temperature. For example, the data indicating the set temperature is transmitted to each sub-controller  552  in advance from a remote controller (not illustrated) or the like. Each sub-controller  552  stores the data indicating the set temperature received from the remote controller or the like in a storage device  552   b  (see  FIG. 14 ) such as a built-in memory. Each sub-controller  552  transmits the value of the set temperature to the main controller  551 . On the basis of the set temperature, the main controller  551  determines a target air flow volume for each fan unit  530  according to the temperature detected by the corresponding remote sensor  570 . The main controller  551  transmits the value of the target air flow volume to each sub-controller  552 . 
     The main controller  551  determines the output of the second fan  521  according to the total combined target air flow volume to be supplied to the air conditioned space SA. 
     For example, if the case where the static pressure at the exit  541   b  of the main pipe  541  (entrance  542   a  of the branch pipe  542 ) takes an intermediate value between the static pressure at the entrance  541   a  of the main pipe  541  and the static pressure at the exits  542   b  of the branch pipe  542  is compared to the case of taking a larger value than the intermediate value, the ratio of the output of the second fan  521  is larger than the ratio of the output of the plurality of first fans  531  in the case of taking a larger value than the intermediate value. Conversely, if the case where the static pressure at the exit  541   b  of the main pipe  541  (entrance  542   a  of the branch pipe  542 ) takes the intermediate value is compared to the case of taking a value smaller than the intermediate value, the ratio of the output of the second fan  521  is smaller than the ratio of the plurality of first fans  531  in the case of taking a smaller value. An efficient range exists for the ratio of the output of the second fan  521  and the output of the plurality of first fans  531 . Accordingly, the main controller  551  determines the output of the second fan  521  such that an efficient ratio is achieved. In other words, the main controller  551  determines the outputs of the second fan  521  to be a predetermined suitable output with respect to the total combined target air flow volume. 
     For example, if a method of determining the output of the second fan  521  like the following is considered, a range of the output of the second fan  521  suitable for reducing the power consumption of the output of the second fan  521  is demonstrated to exist. If the output of the second fan  521  is raised such that the total power consumption by the second fan  521  and the plurality of first fans  531  rises, the output of the second fan  521  is gradually decreased, and if the output of the second fan  521  is determined before the total power consumption by the second fan  521  and the plurality of first fans  531  rebounds, the range of the determined output is a range in which the power consumption is smaller compared to other ranges. Conversely, if the output of the second fan  521  is decreased such that the total power consumption by the second fan  521  and the plurality of first fans  531  rises, the output of the second fan  521  is gradually raised, and if the output of the second fan  521  is determined before the total power consumption by the second fan  521  and the plurality of first fans  531  rebounds, the range of the determined output is a range in which the power consumption is smaller compared to other ranges. If the output of the second fan  521  is raised such that the total power consumption by the second fan  521  and the plurality of first fans  531  decreases, the output of the second fan  521  is gradually raised, and if the output of the second fan  521  is determined before the total power consumption by the second fan  521  and the plurality of first fans  531  rebounds, the range of the determined output is a range in which the power consumption is smaller compared to other ranges. Conversely, if the output of the second fan  521  is decreased such that the total power consumption by the second fan  521  and the plurality of first fans  531  decreases, the output of the second fan  521  is gradually decreased, and if the output of the second fan  521  is determined before the total power consumption by the second fan  521  and the plurality of first fans  531  rebounds, the range of the determined output is a range in which the power consumption is smaller compared to other ranges. However, the method of determining the appropriate output of the second fan  521  is not limited to such a method. 
     After the main controller  551  determines the target air flow volume and transmits the value of the target air flow volume to each of the sub-controllers  552 , each sub-controller  552  adjusts the rotation speed of the fan motor  531   a  of the first fan  531  (the rotation speed of the first fan  531 ) in each corresponding fan unit  530 , except for the fan unit  530  with the highest fan efficiency. The numbers of revolutions of the plurality of first fans  531  of fan motors  531   a  are adjusted independently from each other. 
     At this time, for the determined output of the second fan  521 , the rotation speed of fan motor  531   a  of first fan  531  in the fan unit  530  with the highest fan efficiency is at a maximum. Here, in the case where the static pressure at the entrance  542   a  of the branch pipe  542  is the same and the air supply amount to be supplied to the air conditioned space SA is the same, the fan unit  530  with the highest fan efficiency is the fan unit  530  with the lowest energy consumption. Further, in the case where the static pressure at the entrance  542   a  of the branch pipe  542  is the same and the air supply amount to be supplied to the air conditioned space SA is the same, the fan unit  530  with the lowest fan efficiency is the fan unit  530  with the highest energy consumption. 
     Each sub-controller  552  controls the rotation speed of each fan motor  531   a  of the first fan  531  such that the air supply amount matches the target air flow volume. The plurality of sub-controllers  552  control the numbers of revolutions of the plurality of fan motors  531   a  of first fans  531  independently from each other. If the air flow volume detected by the second air flow volume detecting means  532  is small compared to the target air flow volume, each sub-controller  552  increases the rotation speed of each fan motor  531   a  of the first fan  531 . If the air flow volume detected by the second air flow volume detecting means  532  is large compared to the target air flow volume, each sub-controller  552  decreases the rotation speed of each fan motor  531   a  of the first fan  531 . If the rotation speed of the fan unit  530  with the highest fan efficiency falls, the main controller  551  makes an adjustment by changing the output of the second fan  521  such that the rotation speed of the fan unit  530  with the highest fan efficiency is maximized. 
     In the case of changing the operating state of at least one of the plurality of first fans  531  or changing the air flow volume of at least one of the plurality of first fans  531 , the main controller  551  prioritizes increasing the output of a fan with high fan efficiency or decreasing the output of a fan with low fan efficiency from among the second fan  521  and the plurality of first fans  531 . In other words, in the case of increasing the air supply amount to be supplied to the air conditioned space SA, the main controller  551  determines the output of the second fan  521  and the target air flow volume of the plurality of fan units  530  to increase the output of a fan with high fan efficiency from among the second fan  521  and the plurality of first fans  531 . Conversely, in the case of decreasing the air supply amount to be supplied to the air conditioned space SA, the main controller  551  determines the output of the second fan  521  and the target air flow volume of the plurality of fan units  530  to decrease the output of a fan with high fan efficiency from among the second fan  521  and the plurality of first fans  531 . 
     However, in the case where the air flow volume of the fan unit  530  with the maximum fan efficiency among the plurality of fan units  530  does not reach the target air flow volume, the main controller  551  increases the output of the first fan  3 . At this time, the main controller  551  increases the output of the first fan  3  and also keeps the rotation speed of the fan motor  531   a  of the first fan  531  in the fan unit  530  with the maximum fan efficiency at maximum. 
     (12) Controller 
     The controller  550  is achieved by a computer. The controller  550  is provided with control computing devices  551   a  and  552   a , and storage devices  551   b  and  552   b . For the control computing devices  551   a  and  552   a , a processor such as a CPU or GPU may be used. The control computing devices  551   a  and  552   a  read out programs stored in the storage devices  551   b  and  552   b , and perform predetermined image processing and arithmetic processing according to the programs. Furthermore, the control computing devices  551   a  and  552   a  may follow the programs to write arithmetic results to the storage devices  551   b  and  552   b  or read out information stored in the storage devices  551   b  and  552   b . In  FIG. 14 , various function blocks achieved by the control computing devices  551   a  and  552   a  are illustrated. The storage devices  551   b  and  552   b  may be used as databases. 
     (13) Modifications 
     (13-1) Modification 3A 
     As illustrated in  FIG. 15 , an outdoor air introduction unit  610  may also be attached to the heat exchanger unit  520 . The outdoor air introduction unit  610  includes a third fan  611  and a third air flow volume detecting means  612 . The outdoor air introduction unit  610  uses the third fan  611  to take in and send outdoor air OAr from outside the air conditioned space SA to the heat exchanger unit  520 . The third air flow volume detecting means  612  detects the air flow volume of the outdoor air OAr sent to the heat exchanger unit  520 . The third air flow volume detecting means  612  transmits the detected value of the sent air flow volume of the outdoor air OAr to the main controller  551 . In the case where the outdoor air OAr is sent from the outdoor air introduction unit  610  to the heat exchanger unit  520 , the main controller  551  may be configured to correct the control of the output of the second fan  521  according to the sent air flow volume of the outdoor air OAr. For the third air flow volume detecting means  612 , an air flow sensor, a wind speed sensor, or a differential pressure sensor may be used, for example. 
     (14) Characteristics 
     14-1 
     The air conditioning system  510  according to the third embodiment is provided with the controller  550 , the plurality of ducts  540 , and the plurality of fan units  530 . The plurality of ducts  540  distribute conditioned air that has passed through the use side heat exchanger  522  of the heat exchanger unit  520 . The plurality of fan units  530  are provided in correspondence with the plurality of ducts  540 , and supply conditioned air from the heat exchanger unit  520  to the air conditioned space SA through the plurality of ducts  540 . A plurality of actuators, namely the plurality of fan motors  531   a , are configured to change the air supply amount of conditioned air to be supplied to the air conditioned space SA. Each of the plurality of ducts  540  is disposed in one of a plurality of distribution flow paths. Each of the plurality of fan units  530  includes a first fan, and is disposed in one of the plurality of distribution flow paths. Each of the plurality of actuators is disposed in one of the plurality of distribution flow paths. By controlling the plurality of fan motors  531   a , the controller  300  controls the air supply amount of each of the plurality of fan units  530 . As a result, the air conditioning system  510  according to the third embodiment can adjust the air flow volume passing through the use side heat exchanger  522  such that heat is exchanged efficiently in the use side heat exchanger  522 , and energy consumption can be moderated. 
     14-2 
     In the air conditioning system  510  according to the third embodiment, the controller  550  controls the plurality of fan motors  531   a  according to a plurality of instructions related to the air supply amounts of the plurality of fan units  530 . Consequently, the controller  550  controls the plurality of fan motors  531   a  according to the instructions related to the air supply amounts with respect to the plurality of fan motors  531   a , and adjusts the air flow volume passing through the use side heat exchanger  522  such that heat is exchanged efficiently in the use side heat exchanger  522  to moderate energy consumption. 
     14-3 
     In the air conditioning system  510  of the third embodiment, the controller  550  includes the main controller  551  for sending a plurality of instructions and at least one sub-controller  552  for receiving the plurality of instructions from the main controller  551 . The at least one sub-controller  552  controls the plurality of fan motors  531   a  on a basis of the plurality of instructions. As a result, the control by the main controller  551  is simplified, making it easy to change the duct design and layout of the system. 
     14-4 
     In the air conditioning system  510  of the third embodiment, each of the plurality of fan units  530  includes the second air flow volume detecting means  532  that is air flow volume detector for detecting volume of air passing through the unit. Each of the plurality of sub-controllers  552  controls the number of rotations of the fan motor  531   a  in a manner to bring the air flow volume detected by the second air flow volume detecting means  532  closer to the air supply amount instructed by the main controller  551 . As a result, the sub-controller  552  can reliably controls the air supply amounts of the fan units  530 . 
     14-5 
     In the air conditioning system  510  of the third embodiment, the controller  550  calculates the air supply amount of each of the fan units  530  on the basis of the temperature difference between the indoor air temperature to be adjusted by each of the plurality of fan units  530  and the set temperature, and determines a plurality of instructions on the basis of the calculated air supply amount. Consequently, in the air conditioning system  510 , temperature control of the air conditioned space is achieved easily by changing the air supply amount. 
     14-6 
     In the air conditioning system  510  according to the third embodiment, the heat exchanger unit  520  includes the second fan  521 . In the air conditioning system  510 , the controller  550  controls the second fan  521  on the basis of the air supply amounts of the plurality of fan units  530 . In this way, the controller  550  can control the second fan  521  to an appropriate value to match the air supply amounts of the plurality of first fans  531 , and moderate the energy consumption of the air conditioning system  510 . 
     14-7 
     In the air conditioning system  510  according to the third embodiment, the heat exchanger unit  520  includes the second fan  521 . In the air conditioning system  510 , the controller  550  includes the main controller  551  and the plurality of sub-controllers  552 . The main controller  551  controls the plurality of fan motors  531   a  according to a plurality of instructions related to the air supply amounts of the fan units  530 . The sub-controllers  552  respectively receive the plurality of instructions transmitted by the main controller  551  to control the plurality of fan motors  531   a . The main controller  551  controls the second fan  521  to be a predetermined output with respect to the total combined air supply amount indicated by the plurality of instructions. As a result, in the air conditioning system  510 , the second fan  521  is easily controlled to set the output of the second fan  521  to an appropriate value to match the air supply amounts of the plurality of first fans  531 . The embodiments of the present disclosure have been described above, but it will be understood that various modifications can be made to the embodiments and details without departing from the object and the scope of the present disclosure recited in the claims. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1 ,  510 : Air conditioning system 
               10 ,  520 : Heat exchanger unit 
               11 ,  522 : Use side heat exchanger 
               20 ,  20   a  to  20   e ,  540 : Duct 
               30 ,  30   a  to  30   d ,  30 M,  30 GM,  30 S,  530 : Fan unit 
               32 ,  32   a  to  32   d : Fan (example of first fan) 
               33 ,  531   a : Fan motor (example of actuator) 
               34 : Fan controller (example of sub-controller) 
               38 : Damper 
               39 : Driving motor (example of actuator) 
               40 : Main controller 
               50 : Heat source unit 
               51 : Compressor 
               52 : Heat source side heat exchanger 
               53 : Expansion valve 
               60 ,  60   a  to  60   d : Remote controller 
               74 : Air deflector 
               75 : Air deflector motor (example of actuator) 
               101 : Intake temperature sensor 
               102 : Gas-side temperature sensor (example of heat medium temperature sensor) 
               103 : Liquid-side temperature sensor (example of heat medium temperature sensor) 
               104 : Use side heat exchanger temperature sensor (example of heat medium temperature sensor) 
               121 : Differential pressure sensor (example of air flow volume detector) 
               300 : Controller 
               531 : First fan 
               521 : Second fan 
               550 : Controller 
               551 : Main controller 
               552 : Sub-controller 
             SA: Air conditioned space 
           
         
       
    
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: JP H11-132489 A