Control method for heat source equipment and air conditioning system

Abstract

To provide a control method of a heat source machine which can suppress the unnecessary activation of the heat source machine, and an air-conditioning system.SOLUTION: An air-conditioning system having a plurality of heat source machines at a primary side sets, with respect to a water sending temperature at a secondary side, an increased-stage temperature at which a stage increase of the heat source machine is performed and an increased-output temperature for increasing an output of the heat source machine in operation, and executes at least either of the following items as primary-side control in an operation performed by a part of the heat source machines. a) With respect to a heating operation, the increased-stage temperature is set as a temperature which is lower than a set value of the water sending temperature at the secondary side, and sets the increased output temperature as a value which is lower than the set value of the water sending temperature at the secondary side, and is higher than the increased-stage temperature. b) With respect to a cooling operation, the increased-stage temperature is set as a temperature which is higher than the set value of the water sending temperature at the secondary side, and sets the increased-output temperature as a value which is higher than the set value of the water sending temperature at the secondary side, and is lower than the increased-stage temperature.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an air conditioning system to which the present invention is applied.

Background Art

[0002] Conventionally, there has been known an air conditioning system including a plurality of heat source units on a primary side, wherein the number of operating heat source units is increased or decreased according to a load heat quantity required on a secondary side (see, for example, Patent Documents 1 and 2 below).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problem to be Solved by the Invention

[0004] In a building equipped with such an air conditioning system, scheduled operation of air conditioning is sometimes performed. For example, only specific floors operate the air conditioner at night, and when a predetermined time in the morning comes, the air conditioning is started on all floors. When such an operation is performed, for the primary side of the air conditioning system, after low-load operation continues, simultaneous start-up of the air conditioners causes the required heat quantity on the secondary side to increase sharply, and the required water supply volume will increase.

[0005] However, even if the required flow rate on the secondary side increases sharply, the primary side cannot immediately respond to this. Until the amount of water supplied from the primary side is secured, the flow rate on the secondary side will be covered by circulation using a bypass channel. In this case, assuming heating operation, the water supplied from the primary side will mix with the water from the outlet side of the air conditioner, causing the supplied water temperature to drop. If a system is used that controls the number of operating heat source units on the primary side according to the supplied water temperature, it is possible that during nighttime operation, the load heat will be covered by a low-power operation of one heat source unit, but in the morning, when the air conditioners start up all at once, the number of heat source units will increase as the supplied water temperature drops (heat source units that were previously off are turned on, increasing the number of operating units).

[0006] However, since the addition of this heat source unit is done according to the water supply temperature and not the amount of heat load on the secondary side, there are cases where the second heat source unit is started even though the required amount of heat load can be covered by increasing the output of one heat source unit.

[0007] Generally, the operation of a heat source unit is unstable for a while after startup, so even if a second heat source unit is started, it takes time for the supply water temperature to rise. Also, if the heat requirement on the secondary side can be met by the operation of one heat source unit, the system will be reduced to one unit after the supply water temperature has risen sufficiently after the second heat source unit has been started. In other words, the second heat source unit will be started unnecessarily, which is undesirable from an energy conservation standpoint.

[0008] In view of these circumstances, the present invention aims to provide a control method for a heat source unit and an air conditioning system that can suppress unnecessary startup of the heat source unit. [Means for solving the problem]

[0009] The present invention relates to a control method for heat source units in an air conditioning system equipped with multiple heat source units on the primary side, characterized in that, with respect to the water supply temperature on the secondary side, an augmentation temperature for adding more heat source units and an output-boosting temperature for increasing the output of the operating heat source units are set, and at least one of the following is performed as control of the primary side while some of the heat source units are in operation. a) With regard to heating operation, the increased stage temperature is set to a temperature lower than the set value of the secondary side water supply temperature, and the increased output temperature is set to a value lower than the set value of the secondary side water supply temperature and higher than the increased stage temperature. b) With regard to cooling operation, the increased stage temperature is set to a temperature higher than the set value of the secondary side water supply temperature, and the increased output temperature is set to a value higher than the set value of the secondary side water supply temperature and lower than the increased stage temperature.

[0010] In the above-described control method for the heat source unit, When performing a), with respect to heating operation, if the secondary water supply temperature drops and reaches the increased output temperature, the operating heat source unit will be operated at rated operation. When implementing (b), with respect to cooling operation, the operating heat source unit may be set to rated operation when the secondary water supply temperature rises and reaches the increased output temperature.

[0011] In the above-described control method for the heat source unit, When a) is performed, with respect to heating operation, the reduction temperature is set to a value higher than the increased output temperature, and when the secondary side water supply temperature drops to reach the increased output temperature and then rises to reach the reduced output temperature, the output of the operating heat source unit is reduced. When implementing b), with respect to cooling operation, the reduction temperature may be set to a value lower than the increased output temperature, and the output of the operating heat source unit may be reduced when the secondary side water supply temperature rises to the increased output temperature and then falls to the reduced output temperature.

[0012] The present invention also relates to an air conditioning system comprising a temperature sensor that detects a water supply temperature on a secondary side, and a control device that controls the heat source machine, wherein the air conditioning system is configured to execute the above-described control method for a heat source machine. Effects of the Invention

[0013] According to the control method for a heat source machine and the air conditioning system of the present invention, an excellent effect of suppressing unnecessary activation of the heat source machine can be achieved. Brief Description of the Drawings

[0014] [Figure 1] It is a schematic diagram showing an example of the configuration of an air conditioning system to which the present invention is applied. [Figure 2] It is a conceptual diagram showing an operating state of the air conditioning system of Fig. 1 when the load is low. [Figure 3] It is a conceptual diagram showing an operating state when the flow rate on the secondary side rapidly increases from the state shown in Fig. 2. [Figure 4] It is a conceptual diagram explaining an example of the relationship between the water supply temperature on the secondary side and the operation control on the primary side during heating. [Figure 5] It is a conceptual diagram showing an operating state after the flow rate on the secondary side rapidly increases in the air conditioning system of the present embodiment. [Figure 6] It is a conceptual diagram showing an operating state after the flow rate on the secondary side rapidly increases in an air conditioning system as a reference example of the present invention. [Figure 7] It is a diagram conceptually showing changes in water supply temperature accompanying scheduled air conditioning operation in the embodiment and the reference example of the present invention. [Figure 8] It is a conceptual diagram explaining an example of the relationship between the water supply temperature on the secondary side and the operation control on the primary side during cooling. Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0016] Fig. 1 shows an example of an air conditioning system as an application object of the present invention. In this embodiment, the figure illustrates a system including two heat source units 1 and two pumps (primary pumps) 2 (heat source units 1a, 1b and primary pumps 2a, 2b) respectively on the primary side, and four air conditioners 3 (air conditioners 3a to 3d) and one pump 4 on the secondary side.

[0017] Between the primary-side heat source unit 1 and primary pump 2, and the secondary-side air conditioners 3, there are provided a primary supply header 5, a secondary supply header 6, a secondary return header 7 and a primary return header 8, and water as a heat medium is circulated among these components.

[0018] The primary return header 8 and the primary supply header 5 are connected by two primary flow passages 9. In the middle of each primary flow passage 9, one primary pump 2 (2a, 2b) and one heat source unit 1 (1a, 1b) are respectively provided, with the heat source unit located downstream of the primary pump.

[0019] The secondary supply header 6 and the secondary return header 7 are connected by a secondary flow passage 10. The secondary flow passage 10 branches into four branch flows in the middle, and one air conditioner 3 is provided in the middle of each branched branch flow. An on-off valve 11 (11a to 11d) is respectively provided upstream of each air conditioner 3 (3a to 3d). The four branch flows rejoin into one flow downstream of each air conditioner 3.

[0020] The primary supply header 5 and the secondary supply header 6 are connected by a communication passage 12, and a pump (secondary pump) 4 is provided in the middle of the communication passage. The secondary return header 7 and the primary return header 8 are connected by a communication passage 13.

[0021] In this type of air conditioning system, water circulates from the primary return header 8 through the primary pump 2 and heat source unit 1 to the primary supply header 5, from the primary supply header 5 to the secondary supply header 6, from the secondary supply header 6 through the on-off valve 11 and the coil of the air conditioner 3 to the secondary return header 7, and from the secondary return header 7 to the primary return header 8. Furthermore, the primary return header 8 and the primary supply header 5 are connected by a bypass channel 14, through which water as a heat transfer medium flows as needed. Specifically, when the amount of water supplied on the primary side is greater than the flow rate on the secondary side (primary rich), the excess water flows from the primary supply header 5 towards the primary return header 8, and when the flow rate on the secondary side is greater than the amount of water supplied on the primary side (secondary rich), the excess water flows from the primary return header 8 towards the primary supply header 5. This water flow is driven by the primary pump 2 and the secondary pump 4.

[0022] A temperature sensor 15 is installed upstream of the branching point to the side flow in the secondary flow channel 10, where the temperature of the water supplied on the secondary side (the temperature of the heat transfer medium sent to the air conditioner 3) is measured.

[0023] The operation of each component, such as the heat source unit 1, primary pump 2, air conditioner 3, secondary pump 4, and on-off valve 11, is controlled by the control device 16. The control device 16 is a central monitoring device that monitors and controls the operation of each component that makes up the air conditioning system. In particular, in this embodiment, the secondary side water supply temperature measured by the temperature sensor 15 is input to the control device 16 as a measurement signal, and the operating status of the primary side (on / off and output of each heat source unit 1a, 1b and each primary pump 2a, 2b) is controlled based on this signal.

[0024] It should be noted that the number of heat source units 1, air conditioners 3, pumps 2 and 4, and the flow path configuration may differ from the example shown here. Furthermore, actual air conditioning systems include various other devices and sensors in addition to those illustrated here; however, components not directly related to the essence of this invention are omitted from the illustration.

[0025] Next, the operation of the above-described embodiment will be explained.

[0026] This explanation assumes a heating operation scenario. At night, as shown in Figure 2, on the secondary side, only some of the air conditioners 3 (in this case, one air conditioner 3a located on the far left of the figure) are operating, and the on-off valve 11a upstream of it is open, resulting in low-load operation. On the primary side, only some of the heat source units 1 and primary pumps 2 (in this case, one heat source unit 1a located on the right side of the figure and the primary pump 2a upstream of it) are operating, and water as a heat transfer medium circulates between the heat source unit 1a, the primary pump 2a, and the air conditioner 3a. In Figures 2, 3, 5, and 6, the operating status of each heat source unit 1 and pumps 2 and 4, and the open / closed status of each on-off valve 11 are shown in black. Black indicates an on or open state, and an unfilled state indicates an off or closed state.

[0027] From the primary side (heat source unit 1a and primary supply header 5), a small amount of water is sent out by low-power operation, and from the secondary side (secondary return header 7), a small amount of water is returned to the primary side to supply the heat required by one operating air conditioner 3a (see arrows in the figure. In Figure 2, the size of the arrows represents the amount of water, and the filled color represents the temperature; black arrows indicate high temperature, white arrows indicate low temperature, and diagonal arrows indicate intermediate temperatures. The same applies to Figures 3, 5, and 6, which will be explained later). If the amount of water that can supply the load heat required on the secondary side falls below the minimum output of the primary pump 2a, the excess amount of water sent out from the heat source unit 1a will flow through the bypass channel 14 from the primary supply header 5 to the primary return header 8 (not shown in the figure).

[0028] From this state, when the secondary air conditioners 3 are started simultaneously by the scheduled operation of the air conditioning system (see Figure 3), the on-off valves 11a to 11d upstream of the four air conditioners 3a to 3d open. The secondary pump 4 increases its output to supply water as a heat transfer medium to the four air conditioners 3a to 3d, and water necessary for the operation of the four air conditioners 3a to 3d flows to the secondary side (see the arrows from the primary supply header 5 to the secondary supply header 6, and from the secondary return header 7 to the primary return header 8).

[0029] In response to this sudden increase in flow rate on the secondary side, the primary side cannot immediately keep up, and the flow rate on the secondary side temporarily becomes excessive compared to the primary side. In this case, the excess water flows from the primary return header 8 to the primary supply header 5. As a result, the water sent from the primary side to the secondary side (from the primary supply header 5 to the secondary supply header 6) is mixed with water that is returned from the secondary side and does not pass through the heat source unit 1, causing the water temperature on the secondary side (the water temperature measured by the temperature sensor 15) to decrease.

[0030] In this embodiment, the on / off switching and operation control of the primary side (each heat source unit 1 and primary pump 2) is performed based on the secondary side water supply temperature. Specifically, for example, while one heat source unit 1a is in operation, if the secondary side water supply temperature falls below a threshold relative to the set value (for example, if it falls below the set value -4°C), the number of operating heat source units 1 is increased (the second heat source unit 1b and primary pump 2b are turned on). (Hereafter, the temperature value corresponding to this threshold will be referred to as the "increased temperature"). Up to this point, the control is similar to that of a conventional two-pump type air conditioning system, but in this embodiment, the output of the first heat source unit 1a and primary pump 2a is increased before increasing the number of heat source units 1, and operation is performed at the rated output. In heating operation, for example, as described above, the stage-up temperature is set to the set temperature - 4°C, and the heat source unit 1 is added on the condition that the secondary side water supply temperature is below this stage-up temperature. However, before reaching that temperature, the output of the heat source unit 1a and the primary pump 2a is increased on the condition that the water supply temperature becomes lower than the set value but higher than the stage-up temperature (for example, below the set value - 3°C) (hereinafter, this temperature value will be referred to as the "increased output temperature").

[0031] Such control can be represented as shown in the diagram in Figure 4. In Figure 4, the lower line represents a state in which normal variable flow rate control is performed on the primary side by some of the heat source units 1a and primary pumps 2a, that is, the primary pumps 2a operate with a variable flow rate and the heat source unit 1a operates with the outlet temperature set to the normal operating setting value. The upper line represents a state in which the output of the heat source unit 1a and primary pumps 2a is increased, the heat source unit 1a operates at its rated temperature with the outlet temperature set to the secondary side water supply temperature setting value, and the primary pumps 2a also operate at their rated temperature. The left-right direction corresponds to the secondary side water supply temperature, with the left side representing a low temperature state and the right side representing a high temperature state.

[0032] The control device 16 (see Figure 1) is configured to increase the number of heat source units 1 (turning on heat source unit 1b and primary pump 2b) when, while only a portion of the heat source unit 1 (heat source unit 1a) is operating in normal variable flow rate mode (lower part of the figure), the secondary water supply temperature input from the temperature sensor 15 reaches the increased output temperature (below a threshold (-4°C) relative to the set value (SP)). In addition, the control device 16 is configured to start rated operation of the operating heat source unit 1a and primary pump 2a (upper part of the figure) when the secondary water supply temperature is below the set value and below a threshold higher than the increased output temperature (increased output temperature; set value -3°C).

[0033] If the amount of heat load on the secondary side is such that it can be supplied by the operation of some of the heat source units 1 (heat source unit 1a) that were operating up to that point, the secondary side supply water temperature will recover by operating heat source unit 1a and primary pump 2a at their rated capacity before the heat source unit 1 is increased in number (i.e., before the secondary side supply water temperature drops to the increased-capacity temperature). Once the supply water temperature has recovered and reached a threshold higher than the increased-capacity temperature (for example, the set value of the supply water temperature minus 1°C; hereafter, this temperature will be referred to as the "decreased-capacity temperature"), rated operation is terminated, the output of heat source unit 1a and primary pump 2a is reduced, and operation returns to variable flow rate control.

[0034] With this control, as shown in Figure 3, the flow rate on the secondary side increases and the supply water temperature on the secondary side decreases. Then, as shown in Figure 5, the output of the heat source 1a and primary pump 2a increases, the bypass amount from the primary return header 8 to the primary supply header 5 decreases (or the bypass amount becomes zero, or a primary-rich state is created where water flows from the primary supply header 5 to the primary return header 8), and the supply water temperature on the secondary side recovers while only some of the heat source 1 and primary pump 2 (heat source 1a and primary pump 2a) are operating. If the heat on the secondary side can be supplied by the operation of the heat source 1a that was already running, the need to add another heat source 1 (turn on heat source 1b) is avoided.

[0035] Assuming that there is no setting for increased output temperature as described above, and that the control is only performed so that the heat source unit 1 is increased in number when the supply water temperature reaches the increased stage temperature, then, as shown in Figure 3, the flow rate on the secondary side increases and the supply water temperature on the secondary side decreases, and then, as shown in Figure 6 as a reference example, the second heat source unit 1b and primary pump 2b will start up. However, since heat source units generally take time to stabilize after starting up, even if the flow rate on the primary side increases due to the operation of primary pump 2b, a sufficient amount of heat will not be supplied from heat source unit 1b for some time. In other words, it takes time for the required air conditioning state to be achieved on the secondary side. Furthermore, in air conditioning systems equipped with multiple heat source units, different types of heat source units may be installed, and in such cases, there is a need to mainly use the heat source unit with the best energy efficiency. In such air conditioning systems, if the other heat source units are started up even though some (energy-efficient) heat source units can supply the required amount of heat, the overall energy efficiency will deteriorate. As in this embodiment, by controlling the system to set both the stage-up temperature and the output-up temperature, the output of the operating heat source unit 1a is increased before the secondary-side water supply temperature reaches the stage-up temperature. This suppresses unnecessary stage-up of the heat source unit 1, allows for the rapid supply of the increased heat requirement on the secondary side, and improves energy efficiency.

[0036] Figure 7 is a diagram conceptually comparing the changes in the supply water temperature in this embodiment, where an increased output temperature is set, and in a reference example where an increased output temperature is not set. The supply water temperature on the secondary side detected by the temperature sensor 15 (see Figure 1) (top row in Figure 7) decreases as the flow rate on the secondary side increases after the simultaneous startup of the air conditioners 3 (time t0).

[0037] In the example where no increased output temperature is set (shown by the dashed line), the supply water temperature will gradually rise after it drops to the increased stage temperature (SP-4℃) (let's call this time t1). This is because the second heat source unit 1b starts up after time t1 (dashed line at the bottom of Figure 7). However, since the second heat source unit 1b gradually generates hot water after starting up (dashed line second from the bottom of Figure 7), it takes time for the supply water temperature on the secondary side to recover (let's call this time t2) (dashed line at the top of Figure 7). Furthermore, the first heat source unit 1a continues to generate hot water at a high temperature (dashed line in the second row from the top in Figure 7), and after time t1, the output of the primary pump 2a also gradually increases (dashed line in the third row from the top in Figure 7). However, this hot water mixes with the lower temperature water sent from the heat source unit 1b, so the temperature of the secondary supply water does not recover quickly (dashed line in the top row of Figure 7).

[0038] On the other hand, in the embodiment where the increased output temperature is set (shown by the solid line), after time t0, when the supplied water temperature drops to the increased output temperature (SP-3℃) (let's call this time t3), the primary pump 2a starts rated operation and the output increases sharply (solid line in the third row from the top in Figure 7). As a result, the temperature of the hot water at the outlet of the heat source unit 1a temporarily decreases, but the heat source unit 1a also starts rated operation and the output increases, and the temperature recovers (solid line in the second row from the top in Figure 7). Moreover, since the heat source unit 1a had been operating up to that point, the time it takes for the temperature to recover is short.

[0039] When the secondary supply water temperature reaches the reduced output temperature (SP-1°C), the heat source unit 1a and primary pump 2a terminate rated operation and return to operation with variable flow rate control (time t4). Through this control, the secondary supply water temperature recovers to the set value in a short time between time t0 and time t5 (solid line in the uppermost section of Figure 7).

[0040] The above explanation uses the heating operation as an example, but similar control can be applied to the cooling operation. In that case, for example, as shown in Figure 8, the stage increase temperature, the power increase temperature, and the power decrease temperature are set. While only a portion of the heat source units are operating under normal variable flow rate conditions (lower part of the diagram), if the secondary side supply water temperature reaches or exceeds the step-up temperature (a threshold (+4°C) relative to the set value (SP)), the heat source units are increased. In addition, if the secondary side supply water temperature exceeds the set value and is lower than the step-up temperature (a threshold (increased output temperature; set value +3°C)), the operating heat source units and primary pumps begin rated operation (upper part of the diagram). If the load heat on the secondary side is an amount that can be covered by the operation of the portion of heat source units 1 that was operating up to that point, the secondary side supply water temperature recovers through rated operation of the heat source units and primary pumps before the heat source units are increased (i.e., before the secondary side supply water temperature rises to the step-up temperature). If the supply water temperature drops and reaches the reduced output temperature (set value +1°C), rated operation ends, the output of the heat source units and primary pumps is reduced, and normal operation with variable flow rate control is returned.

[0041] As described above, in this embodiment, in an air conditioning system equipped with multiple heat source units 1 on the primary side, with respect to the water supply temperature on the secondary side, an augmentation temperature for increasing the number of heat source units 1 and an output-boosting temperature for increasing the output of the operating heat source unit 1 are set, and at least one of the following is performed as control of the primary side while some of the heat source units 1a are operating. a) With regard to heating operation, the increased stage temperature is set to a temperature lower than the set value of the secondary side water supply temperature, and the increased output temperature is set to a value lower than the set value of the secondary side water supply temperature and higher than the increased stage temperature. b) With regard to cooling operation, the increased stage temperature is set to a temperature higher than the set value of the secondary side water supply temperature, and the increased output temperature is set to a value higher than the set value of the secondary side water supply temperature and lower than the increased stage temperature.

[0042] Furthermore, the air conditioning system of this embodiment includes a temperature sensor 15 for detecting the water supply temperature on the secondary side and a control device 16 for controlling the heat source unit 1, and is configured to execute the heat source unit control method described above.

[0043] In this way, in an air conditioning system that increases or decreases the number of operating heat source units 1 according to the secondary water supply temperature, the number of additional heat source units 1 can be suppressed by increasing the output of the operating heat source unit 1a before the secondary water supply temperature reaches the additional stage temperature.

[0044] Furthermore, in the control method of the heat source unit in this embodiment, When performing a), with respect to heating operation, if the secondary water supply temperature drops and reaches the increased output temperature, the operating heat source unit 1a will be operated at rated operation. When implementing b), with regard to cooling operation, the operating heat source unit 1a is set to rated operation when the secondary water supply temperature rises and reaches the increased output temperature.

[0045] Furthermore, in the control method of the heat source unit in this embodiment, When a) is performed, with respect to heating operation, the reduced output temperature is set to a value higher than the increased output temperature, and when the secondary side water supply temperature drops to reach the increased output temperature and then rises to reach the reduced output temperature, the output of the operating heat source unit 1a is reduced. When performing (b), with respect to cooling operation, the reduction temperature is set to a value lower than the increased output temperature, and when the secondary side water supply temperature rises to the increased output temperature and then falls to the reduced output temperature, the output of the operating heat source unit 1a is reduced.

[0046] Therefore, according to the above embodiment, it is possible to suppress the unnecessary startup of the heat source unit.

[0047] Furthermore, the control method for the heat source and the air conditioning system of the present invention are not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention. [Explanation of Symbols]

[0048] 1 Heat source machine 1a Heat source machine 15. Temperature sensor 16 Control device

Claims

1. A method for controlling heat sources in an air conditioning system equipped with multiple heat sources on the primary side, characterized in that, with respect to the water supply temperature on the secondary side, an augmentation temperature for adding more heat sources and an output-boosting temperature for increasing the output of the operating heat sources are set, and at least one of the following is performed as primary side control during operation of some of the heat sources. a) With regard to heating operation, the increased stage temperature is set to a temperature lower than the set value of the secondary side water supply temperature, and the increased output temperature is set to a value lower than the set value of the secondary side water supply temperature and higher than the increased stage temperature. b) With regard to cooling operation, the increased stage temperature is set to a temperature higher than the set value of the secondary side water supply temperature, and the increased output temperature is set to a value higher than the set value of the secondary side water supply temperature and lower than the increased stage temperature.

2. In the control method for a heat source machine described in claim 1, a) When performing heating operation, if the secondary water supply temperature drops and reaches the increased output temperature, the operating heat source unit will be operated at rated operation. When performing (b), with respect to cooling operation, if the secondary water supply temperature rises and reaches the increased output temperature, the operating heat source unit will be operated at its rated capacity. A control method for a heat source machine characterized by the following.

3. In the control method for a heat source machine described in claim 1, When performing a), with respect to heating operation, the reduction temperature is set to a value higher than the increased output temperature, and when the secondary side water supply temperature drops to reach the increased output temperature and then rises to reach the reduced output temperature, the output of the operating heat source unit is reduced. When performing (b), with respect to cooling operation, the reduction temperature is set to a value lower than the increase temperature, and when the secondary side water supply temperature rises to reach the increase temperature and then falls to the reduction temperature, the output of the operating heat source unit is reduced. A method for controlling a heat source machine according to claim 1 or 2, characterized by the above.

4. An air conditioning system comprising a temperature sensor for detecting the water supply temperature on the secondary side and a control device for controlling the heat source unit, and configured to perform the heat source unit control method described in claim 1.

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