SPACE HEATING SYSTEM

Abstract

A space heating system may include: a space heating circuit; a plurality of heat source devices, wherein each of the heat source devices is configured to perform a first heating operation for heating a heat medium flowing in the space heating circuit; a plurality of heat source controllers, wherein each of the heat source controllers is configured to control its corresponding heat source device; a space heating terminal configured for space heating by heat dissipated from the heat medium; a request generator configured to generate a heating request; a request transmitter configured to transmit the heating request to a predetermined heat source controller; and a selector configured to select a heat source device that is to perform the first heating operation. In response to the heating request being transmitted to the predetermined heat source controller, the heat source device selected by the selector may perform the first heating operation.

Claims

1. A space heating system comprising: a space heating circuit in which a heat medium flows; a plurality of heat source devices disposed in parallel to each other in the space heating circuit, wherein each of the heat source devices is configured to perform a first heating operation for heating the heat medium flowing in the space heating circuit; a plurality of heat source controllers, wherein each of the heat source controllers is provided for corresponding one of the plurality of heat source devices and is configured to control its corresponding heat source device; a space heating terminal configured for space heating by heat dissipated from the heat medium flowing in the space heating circuit; a request generator configured to generate a heating request for the space heating by the space heating terminal; a request transmitter configured to transmit the heating request generated by the request generator to a predetermined heat source controller among the plurality of heat source controllers; and a selector configured to select a heat source device that is to perform the first heating operation from among the plurality of heat source devices, wherein in response to the heating request being transmitted to the predetermined heat source controller, the heat source device selected by the selector performs the first heating operation.

2. The space heating system according to claim 1, wherein the plurality of heat source controllers includes one parent controller and at least one child controller communicable with the parent controller, and the parent controller functions as the selector.

3. The space heating system according to claim 1, further comprising a pump configured to deliver the heat medium flowing in the space heating circuit to the space heating terminal, wherein in response to the heating request being transmitted to the predetermined heat source controller, the predetermined heat source controller activates the pump.

4. The space heating system according to claim 2, further comprising a pump configured to deliver the heat medium flowing in the space heating circuit to the space heating terminal, wherein in response to the heating request being transmitted to the predetermined heat source controller, the parent controller activates the pump.

5. The space heating system according to claim 3, wherein when at least one of the plurality of heat source devices is unable to perform the first heating operation, operation of the pump is prohibited.

6. The space heating system according to claim 5, further comprising a hot-water supply circuit in which water flows, wherein each of the plurality of heat source devices is further configured to perform a second heating operation for heating the water flowing in the hot-water supply circuit, and each of the plurality of heat source devices is unable to perform the first heating operation while the heat source device is performing the second heating operation.

7. The space heating system according to claim 1, wherein the space heating terminal comprises a plurality of space heating terminals, the request generator comprises a plurality of request generators, wherein each of the plurality of request generators is provided for corresponding one of the plurality of space heating terminals, and the request transmitter comprises a plurality of request transmitters provided for corresponding one of the plurality of request generators.

8. The space heating system according to claim 4, wherein when at least one of the plurality of heat source devices is unable to perform the first heating operation, operation of the pump is prohibited, the space heating system further comprises a hot-water supply circuit in which water flows, each of the plurality of heat source devices is further configured to perform a second heating operation for heating the water flowing in the hot-water supply circuit, each of the plurality of heat source devices is unable to perform the first heating operation while the heat source device is performing the second heating operation, the space heating terminal comprises a plurality of space heating terminals, the request generator comprises a plurality of request generators, wherein each of the plurality of request generators is provided for corresponding one of the plurality of space heating terminals, and the request transmitter comprises a plurality of request transmitters provided for corresponding one of the plurality of request generators.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0019] FIG. 1 schematically shows a configuration of a space heating system 2 according to an embodiment.

[0020] FIG. 2 shows a heat medium flow during a first heating operation performed by a heat source device 100 of the space heating system 2 according to the embodiment.

[0021] FIG. 3 shows a heat medium flow during a second heating operation performed by the heat source device 100 of the space heating system 2 according to the embodiment.

[0022] FIG. 4 shows an exemplary diagram illustrating whether each heat source device 100, 200, 300, 400, 500 is able to perform the first heating operation or not and priorities assigned to the heat source devices 100, 200, 300, 400, 500 in the space heating system 2 according to the embodiment.

[0023] FIG. 5 shows a flowchart of a heat source selecting process performed by a parent controller 102 of the space heating system 2 according to the embodiment.

[0024] FIG. 6 shows a flowchart of a setting value increasing process performed by the parent controller 102 of the space heating system 2 according to the embodiment.

DETAILED DESCRIPTION

Embodiment

[0025] As shown in FIG. 1, a space heating system 2 comprises a hot-water supply circuit 4 (only partially shown), a space heating circuit 6, five heat source devices 100, 200, 300, 400, 500, and three space heating terminals 8a, 8b, 8c. Water flows in the hot-water supply circuit 4. A heat medium (e.g., water, an antifreeze liquid, or the like) flows in the space heating circuit 6. The heat source devices 100, 200, 300, 400, 500 are disposed in parallel with each other in the space heating circuit 6 and the hot-water supply circuit 4. The heat source devices 100, 200, 300, 400, 500 are configured to heat the water flowing in the hot-water supply circuit 4 and also heat the heat medium flowing in the space heating circuit 6. Faucets and bathtubs (not shown) are disposed in the hot-water supply circuit 4. The space heating terminals 8a, 8b, 8c are disposed in parallel to each other in the space heating circuit 6. The space heating terminals 8a, 8b, 8c include, for example, floor heating devices, panel heaters, and the like. The space heating terminals 8a, 8b, 8c are configured for space heating by heat dissipated from the heat medium flowing in the space heating circuit 6. The space heating system 2 is configured to supply the water heated by the heat source devices 100, 200, 300, 400, 500 to the faucets and bathtubs via the hot-water supply circuit 4. The space heating system 2 is also configured to deliver the heat medium heated by the heat source devices 100, 200, 300, 400, 500 to the space heating terminals 8a, 8b, 8c via the space heating circuit 6 for space heating by the space heating terminals 8a, 8b, 8c.

[0026] The space heating circuit 6 comprises a primary outward channel 12 in which the heat medium is delivered out from each of the heat source devices 100, 200, 300, 400, 500, a primary return channel 14 in which the heat medium is delivered back to each of the heat source devices 100, 200, 300, 400, 500, a secondary outward channel 16 in which the heat medium is delivered to each of the space heating terminals 8a, 8b, 8c, and a secondary return channel 18 in which the heat medium is delivered back from each of the space heating terminals 8a, 8b, 8c. A fluid mixer 20 establishes fluid communication between the downstream end of the primary outward channel 12, the upstream end of the primary return channel 14, the upstream end of the secondary outward channel 16, and the downstream end of the secondary return channel 18. The fluid mixer 20 permits a difference between a flow volume of the heat medium flowing in the primary outward channel 12 and the primary return channel 14 (i.e., the total volume of heat medium flowing through the heat source devices 100, 200, 300, 400, 500) and a flow volume of the heat medium flowing in the secondary outward channel 16 and the secondary return channel 18 (i.e., the total volume of heat medium flowing through the space heating terminals 8a, 8b, 8c).

[0027] The space heating circuit 6 further comprises terminal channels 22a, 22b, 22c corresponding to the space heating terminals 8a, 8b, 8c, respectively. Upstream ends of the terminal channels 22a, 22b, 22c are connected to the secondary outward channel 16. Downstream ends of the terminal channels 22a, 22b, 22c are connected to the secondary return channel 18. Terminal pumps 24a, 24b, 24c are disposed on the terminal channels 22a, 22b, 22c, respectively. The terminal pumps 24a, 24b, 24c draw the heat medium flowing in the secondary outward channel 16 into the terminal channels 22a, 22b, 22c and pump out the heat medium in the terminal channels 22a, 22b, 22c to the secondary return channel 18. By the operation of the terminal pumps 24a, 24b, 24c, the heat medium is delivered to the space heating terminals 8a, 8b, 8c for space heating.

[0028] The space heating system 2 comprises thermostats 26a, 26b, 26c corresponding to the space heating terminals 8a, 8b, 8c, respectively. The thermostats 26a, 26b, 26c detect temperatures in spaces in which corresponding space heating terminals 8a, 8b, 8c are installed, that is, temperatures in spaces heated by the space heating terminals 8a, 8b, 8c (e.g., inside of a house). Further, each of the thermostats 26a, 26b, 26c outputs a heating ON signal for starting the space heating by the corresponding space heating terminal 8a, 8b, 8c when the detected temperature is below a predetermined heating ON threshold (e.g., 20 C.) and outputs a heating OFF signal for terminating the space heating by the corresponding space heating terminal 8a, 8b, 8c when the detected temperature is above a predetermined heating OFF threshold (e.g., 25 C.). In the disclosure herein, the heating ON signal and the heating OFF signal may be both termed heating signal.

[0029] The heat source device 100 comprises a burner 32, a first heat exchanger 34 at which the heat medium is heated by the heat of the burner 32, a branched primary return channel 36 connecting the primary return channel 14 to a fluid inlet of the first heat exchanger 34, a branched primary outward channel 38 connecting a fluid outlet of the first heat exchanger 34 to the primary outward channel 12, a heat source pump 40 disposed on the branched primary return channel 36, a bypass channel 42 that bypasses the first heat exchanger 34 and the heat source pump 40 and connects the branched primary return channel 36 to the branched primary outward channel 38, a second heat exchanger 44 at which the water flowing in the hot-water supply circuit 4 is heated by heat exchange with the heat medium flowing in the bypass channel 42, and a three-way valve 46 disposed at the intersection between the branched primary outward channel 38 and the bypass channel 42. The three-way valve 46 is switched between a first state for delivering the heat medium from the first heat exchanger 34 to the primary outward channel 12 via the branched primary outward channel 38 (see FIG. 2) and a second state for delivering the heat medium from the first heat exchanger 34 to the bypass channel 42 via the branched primary outward channel 38 (see FIG. 3). The three-way valve 46 can switch the destination of the heat medium flowing out from the first heat exchanger 34 between the bypass channel 42 and the primary outward channel 12. A primary return thermistor 48 is disposed on the branched primary return channel 36 and detects the temperature of the heat medium immediately before the heat medium is heated at the first heat exchanger 34. A primary outward thermistor 50 is disposed on the branched primary outward channel 38 and detects the temperature of the heat medium immediately after the heat medium has been heated at the first heat exchanger 34.

[0030] As shown in FIG. 2, the heat source device 100 is configured to perform a first heating operation for heating the heat medium flowing in the space heating circuit 6 by turning on the burner 32 and activating the heat source pump 40 while the three-way valve 46 is in the first state. During the first heating operation, the heat medium in the primary return channel 14 flows through the branched primary return channel 36, the first heat exchanger 34, and the branched primary outward channel 38 in this order and is delivered to the primary outward channel 12. While flowing through the first heat exchanger 34, the heat medium is heated by the heat of the burner 32.

[0031] As shown in FIG. 3, the heat source device 100 is also configured to perform a second heating operation for heating the water flowing in the hot-water supply circuit 4 by turning on the burner 32 and activating the heat source pump 40 while the three-way valve 46 is in the second state. During the second heating operation, the heat medium circulates through the branched primary return channel 36, the first heat exchanger 34, the branched primary outward channel 38, and the bypass channel 42 (i.e., the second heat exchanger 44). The heat medium is heated by the heat of the burner 32 while flowing through the first heat exchanger 34 and dissipates its heat to the hot-water supply circuit 4 while flowing through the second heat exchanger 44. The water flowing in the hot-water supply circuit 4 is thereby heated.

[0032] The heat source device 100 further comprises a heat source controller 102 including a CPU, a ROM, a RAM, etc. Various operation programs are stored in the ROM. Various signals input to the heat source controller 102 and various data generated while the CPU are executing processes are temporarily stored in the RAM. The heat source controller 102 controls each component of the heat source device 100 by the CPU executing processes based on the information stored in the ROM and RAM. The heat source controller 102 can set a setting value for output of the burner 32 (which may be termed output setting value). The output setting value is set to, for example, any of five levels, 1, 2, 3, 4, or 5. When turning on the burner 32 (e.g., causing the heat source device 100 to perform the first heating operation), the heat source controller 102 controls the output of the burner 32 based on the output setting value. The heat source controller 102 increases the output of the burner 32 as the output setting value is larger.

[0033] Each of the heat source devices 200, 300, 400, 500 shown in FIG. 1 comprises the same components as those of the heat source device 100. For example, heat source controllers 202, 302, 402, 502 of the heat source devices 200, 300, 400, 500 are equivalent to the heat source controller 102 and thus control each component of the heat source devices 200, 300, 400, 500. The other components of the heat source devices 200, 300, 400, 500 are not labeled for simplicity.

[0034] A first signal line 62a for communication with the thermostat 26a and a second signal line 64a for communication with the terminal pump 24a are connected to the heat source controller 102 of the heat source device 100. Heating signals from the thermostat 26a are transmitted to the heat source controller 102 via the first signal line 62a. Further, the heat source controller 102 controls the terminal pump 24a by transmitting instructions to the terminal pump 24a via the second signal line 64a. For example, in response to receiving the heating ON signal from the thermostat 26a, the heat source controller 102 activates the terminal pump 24a. Thereby, the heat medium is started to be supplied to the space heating terminal 8a corresponding to the thermostat 26a and thus the space heating by the space heating terminal 8a is started. Thereafter, in response to receiving the heating OFF signal from the thermostat 26a, the heat source controller 102 stops the terminal pump 24a. Thereby, the supply of the heat medium to the space heating terminal 8a corresponding to the thermostat 26a is stopped and thus the space heating by the space heating terminal 8a is stopped.

[0035] A first signal line 62b for communication with the thermostat 26b and a second signal line 64b for communication with the terminal pump 24b are connected to the heat source controller 202 of the heat source device 200. The relationship between the heat source controller 202, the thermostat 26b, the terminal pump 24b, and the space heating terminal 8b is the same as that of the heat source controller 102, the thermostat 26a, the terminal pump 24a, and the space heating terminal 8a. A first signal line 62c for communication with the thermostat 26c and a second signal line 64c for communication with the terminal pump 24c are connected to the heat source controller 302 of the heat source device 300. The relationship between the heat source controller 302, the thermostat 26c, the terminal pump 24c, and the space heating terminal 8c is the same as that of the heat source controller 102, the thermostat 26a, the terminal pump 24a, and the space heating terminal 8a.

[0036] In this embodiment, among the heat source controllers 102, 202 302, 402, 502, the heat source controller 102 functions as a parent controller, while the other heat source controllers 202, 302, 402, 502 function as child controllers communicable with the parent controller. Hereinafter, the heat source controller 102 may be termed parent controller 102 and the heat source controllers 202, 302, 402, 502 may be termed child controllers 202, 302, 402, 502. The parent controller 102 and the child controllers 202, 302, 402, 502 cooperate with each other to control the space heating system 2.

[0037] As shown in FIG. 4, the parent controller 102 manages availabilities of the heat source devices 100, 200, 300, 400, 500 for the first heating operation. For example, a heat source device is unable to perform the first heating operation while performing the second heating operation. Alternatively, a heat source device is unable to perform the first heating operation when an error is occurring therein. The error here means, for example, a failure for a burner to turn on, detection errors of thermistors, etc.

[0038] When all the heat source devices 100, 200, 300, 400 500 are unable to perform the first heating operation (e.g., when all the heat source devices 100, 200, 300, 400, 500 are performing the second heating operation), the parent controller 102 shown in FIG. 1 prohibits the operation of the terminal pump 24a. When all the heat source devices 100, 200, 300, 400 500 are unable to perform the first heating operation, the parent controller 102 also transmits instructions to the child controllers 202 and 302 to prohibit the operations of the terminal pumps 24b and 24c. Thus, when all the heat source devices 100, 200, 300, 400 500 are unable to perform the first heating operation, the operations of the terminal pumps 24a, 24b, and 24c are prohibited. When all the heat source devices 100, 200, 300, 400 500 are unable to perform the first heating operation, the heat medium flowing in the space heating circuit 6 may not be heated to a temperature required for the space heating. In this case, delivering the heat medium to the space heating terminals 8a, 8b, 8c by the terminal pumps 24a, 24b, 24c would not contribute to heating. In this embodiment, the operations of the terminal pumps 24a, 24b, 24c are prohibited when all the heat source devices 100, 200, 300, 400 500 are unable to perform the first heating operation, preventing the terminal pumps 24a, 24b, 24c from operating unnecessarily.

[0039] As shown in FIG. 4, the parent controller 102 assigns a priority for the first heating operation (1, 2, 3, 4) to each of the heat source devices 100, 200, 300, 400, 500. In this embodiment, the parent controller 102 is configured to manage usage frequencies of the burners of the heat source devices 100, 200, 300, 400, 500 (e.g., how many times the burners have been turned on in total, how long the burners have been used in total) and assign higher priorities to the heat source devices comprising the burners with lower usage frequencies. When there is a heat source device that is unable to perform the first heating operation, the parent controller 102 assigns the priorities excluding that heat source device. Thus, a priority is not assigned to the heat source device that is unable to perform the first heating operation (in the example of FIG. 4, the heat source device 500).

[0040] The parent controller 102 shown in FIG. 1 stores the latest heating signal transmitted to the parent controller 102 (i.e., the latest heating signal outputted from the thermostat 26a). Further, the parent controller 102 communicates with the child controllers 202, 302 to acquire the latest heating signals transmitted to the child controllers 202, 302 (i.e., the latest heating signals outputted from the thermostats 26b, 26c) and stores these signals. Thus, the parent controller 102 can identify the latest heating signals outputted from the thermostats 26a, 26b, 26c. The latest heating signals outputted from the respective thermostats 26a, 26b, 26c indicate whether the space heating terminals 8a, 8b, 8c are being used for the space heating or not. If the latest heating signals outputted from the thermostats 26a, 26b, 26c are the heating ON signals, the space heating terminals 8a, 8b, 8c corresponding to the thermostats 26a, 26b, 26c are being used for the space heating. In contrast, if the latest heating signals outputted from the thermostats 26a, 26b, 26c are the heating OFF signals, the space heating terminals 8a, 8b, 8c corresponding to the thermostats 26a, 26b, 26c are not being used for the space heating.

Heat Source Selecting Process: FIG. 5

[0041] When the latest heating signal from at least one of the thermostats 26a, 26b, and 26c is the heating ON signal, at least one of the heat source devices 100, 200, 300, 400, and 500 is to perform the first heating operation (see FIG. 2) to supply the heated heat medium to the corresponding space heating terminal 8a, 8b, 8c because at least one of the space heating terminals 8a, 8b, and 8c is being used for the space heating. Thus, when the latest heating signal from at least one of the thermostats 26a, 26b, and 26c is the heating ON signal, the parent controller 102 performs a heat source selecting process (see FIG. 5) to cause at least one of the heat source devices 100, 200, 300, 400, and 500 to perform the first heating operation.

[0042] In S2, the parent controller 102 determines whether all the heat source devices 100, 200, 300, 400, 500 are unable to perform the first heating operation. When all the heat source devices 100, 200, 300, 400, 500 are unable to perform the first heating operation (YES in S2), the process of FIG. 5 ends. When not all the heat source devices 100, 200, 300, 400, 500 are unable to perform the first heating operation, that is, if at least one of the heat source devices 100, 200, 300, 400, and 500 is able to perform the first heating operation (NO in S2), the process proceeds to S4.

[0043] In S4, the parent controller 102 determines the number of heat source devices that are to perform the first heating operation (this number is termed heat source device number). For example, when a detection value at a flow sensor (not shown) that detects a flow rate of the heat medium flowing in the secondary outward channel 16 is small, the parent controller 102 determines a small number (e.g., one heat source device) as the heat source device number. In contrast, when the detection value at the flow sensor is large, the parent controller 102 determines a large number (e.g., two heat source devices) as the heat source device number. After S4, the process proceeds to S6.

[0044] In S6, the parent controller 102 selects heat source device(s) in the number determined in S4 from among the heat source device(s) able to perform the first heating operation. For this selection, heat source devices with higher priorities are prioritized. If the parent controller 102 determines one as the heat source device number in the example of FIG. 4, the parent controller 102 selects one heat source device 100 with the highest priority from among the heat source devices 100, 200, 300, 400 able to perform the first heating operation. After S6, the process proceeds to S8.

[0045] In S8, the parent controller 102 causes the heat source device(s) selected in S6 to perform the first heating operation. If the heat source devices selected in S6 include the heat source devices 200, 300 controlled by the child controllers 202, 302, the parent controller 102 transmits an instruction for the first heating operation to each of the child controllers 202, 302. The child controllers 202, 302 cause the corresponding heat source devices 200, 300 to perform the first heating operation in response to the instructions from the parent controller 102. After S8, the process of FIG. 5 ends.

Advantages of Heat Source Selecting Process

[0046] In this embodiment, the heat source device 100 is associated with the thermostat 26a via the first signal line 62a, the heat source device 200 is associated with the thermostat 26b via the first signal line 62b, and the heat source device 300 is associated with the thermostat 26c via the first signal line 62c. Conventionally, these associations are usually used to cause the heat source device 100 to perform the first heating operation when the thermostat 26a outputs the heating ON signal, cause the heat source device 200 to perform the first heating operation when the thermostat 26b outputs the heating ON signal, and cause the heat source device 300 to perform the first heating operation when the thermostat 26c outputs the heating ON signal. However, in this embodiment, when at least one of the thermostats 26a, 26b, and 26c outputs the heating ON signal, heat source device(s) selected regardless of the above associations perform the first heating operation. Specifically, heat source device(s) selected based on the priorities (see FIG. 4) set by the parent controller 102 perform the first heating operation. As described above, in this embodiment, higher priorities are assigned to heat source devices comprising burners with lower usage frequencies. Thus, a heat source device comprising a burner with a lower usage frequency preferentially performs the first heating operation over a heat source device comprising a burner with a higher usage frequency. This suppresses imbalance in the usage frequencies of burners among the heat source devices 100, 200, 300, 400, 500.

Setting Value Increasing Process: FIG. 6

[0047] The parent controller 102 repeats the process shown in FIG. 6 while the space heating system 2 is active.

[0048] In S22, the parent controller 102 determines whether the thermostat 26a has output the heating ON signal. As described above, when the thermostat 26a outputs the heating ON signal, the parent controller 102 activates the terminal pump 24a, thereby starting the space heating by the space heating terminal 8a. Thus, in other words, the parent controller 102 determines in S22 whether the space heating by the space heating terminal 8a has started. When the thermostat 26a does not output the heating ON signal (NO in S22), the process repeats S22, whereas when the thermostat 26a outputs the heating ON signal (YES in S22), the process proceeds to S24.

[0049] In S24, the parent controller 102 acquires an operation state of the heat source device 100 it controls. The parent controller 102 also communicates with the child controllers 202, 302, 402, 502 to acquire operation states of the heat source devices 200, 300, 400, 500. Then, the parent controller 102 determines whether the first heating operation is being performed in at least one of the heat source devices 100, 200, 300, 400, 500 based on the operation states acquired from the heat source devices 100, 200, 300, 400, 500. For example, when the second heating operation (see FIG. 3) is being performed in all the heat source devices 100, 200, 300, 400, 500, the first heating operation is unable to be performed in all the heat source devices 100, 200, 300, 400, 500. In this case, even when the thermostat 26a outputs the heating ON signal, the first heating operation is not performed in any of the heat source devices 100, 200, 300, 400, 500 (i.e., NO in S24). When the first heating operation is not being performed in any of the heat source devices 100, 200, 300, 400, 500 (NO in S24), the process proceeds to S26.

[0050] In S26, the parent controller 102 determines whether the thermostat 26a has output the heating OFF signal. As described above, when the thermostat 26a outputs the heating OFF signal, the parent controller 102 stops the terminal pump 24a, thereby stopping the space heating by the space heating terminal 8a. Thus, in other words, the parent controller 102 determines in S26 whether the space heating by the space heating terminal 8a has stopped. When the thermostat 26a outputs the heating OFF signal (YES in S26), the process of FIG. 6 ends, whereas when the thermostat 26a does not output the heating OFF signal (NO in S26), the process returns to S24.

[0051] When the first heating operation is being performed in at least one of the heat source devices 100, 200, 300, 400, 500 in S24 (YES in S24), the process proceeds to S28. In S28, the parent controller 102 starts a time measurement. After S28, the process proceeds to S30.

[0052] In S30, the parent controller 102 determines whether the thermostat 26a has output the heating OFF signal. That is, the parent controller 102 determines whether the space heating by the space heating terminal 8a has stopped. When the thermostat 26a does not output the heating OFF signal (NO in S30), the process proceeds to S32.

[0053] In S32, the parent controller 102 determines whether an elapsed period from the start of time measurement in S28 (this elapsed period is termed time measurement period) has reached a predetermined period or longer. When the time measurement period is shorter than the predetermined period (NO in S32), the process returns to S30, whereas when the time measurement period is equal to or longer than the predetermined period (YES in S32), the process proceeds to S34.

[0054] In S34, the parent controller 102 causes all the heat source devices 100, 200, 300, 400, 500 to increase their output setting values. Specifically, the parent controller 102 increases the output setting value of the heat source device 100 it controls and further transmits an instruction to each of the child controllers 202, 302, 402, 502 to increase the output setting values of the heat source devices 200, 300, 400, 500. The child controllers 202, 302, 402, 502 increase the output setting values of the corresponding heat source devices 200, 300, 400, 500 in response to the instructions from the parent controller 102. Thus, the output setting values are increased in all the heat source devices 100, 200, 300, 400, 500.

[0055] After S34 or when it is determined in S30 that the thermostat 26a has output the heating OFF signal (YES in S30), the process proceeds to S36. The process also proceeds to S36 when the first heating operation is stopped in the heat source devices 100, 200, 300, 400, 500 while the parent controller 102 is performing the time measurement. In S36, the parent controller 102 terminates the time measurement. After S36, the process of FIG. 6 ends.

Advantages of Setting Value Increasing Process

[0056] As described above, the thermostat 26a outputs the heating ON signal when the detected temperature (i.e., the temperature in the space heated by the space heating terminal 8a) is below the heating ON threshold, whereas it outputs the heating OFF signal when the detected temperature is above the heating OFF threshold. Thus, alternate output of the heating ON signal and the heating OFF signal from the thermostat 26a indicates that the temperature in the space heated by the space heating terminal 8a has been maintained at a moderate temperature (in this embodiment, the moderate temperature is equal to or above the heating ON threshold and equal to or below the heating OFF threshold). In contrast, the thermostat 26a not having output the heating OFF signal for a long time after it had output the heating ON signal would indicate that the temperature in the space heated by the space heating terminal 8a has been at a temperature lower than the moderate temperature.

[0057] The time measurement period in this embodiment can be rephrased as a period during which the first heating operation is being performed in at least one of the heat source devices 100, 200, 300, 400, 500 without the heating OFF signal being output from the thermostat 26a after the thermostat 26a has output the heating ON signal. Thus, a long time measurement period means that the temperature in the space heated by the space heating terminal 8a has been at a temperature lower than the moderate temperature despite that the heat medium heated by the heat source device(s) is supplied to the space heating terminal 8a and the space is heated by the space heating terminal 8a. In the setting value increasing process, when the time measurement period is equal to or longer than the predetermined period (i.e., when the time measurement period is long), the output setting values of all the heat source devices 100, 200, 300, 400, 500 are increased. Thereby, the heating performance (i.e., the output of the burner 32) of the heat source device(s) that are performing the first heating operation is increased, the heat source device(s) give an increased amount of heat to the heat medium, and the heat medium dissipates an increased amount of heat at the space heating terminal 8a, resulting in an increase in the temperature in the space heated by the space heating terminal 8a. This breaks the state where the temperature in the space heated by the space heating terminal 8a is at a lower temperature than the moderate temperature.

[0058] In the setting value increasing process, the output setting values of all the heat source devices 100, 200, 300, 400, 500, rather than some of them, are increased. This prevents differences between the output setting values of the heat source devices 100, 200, 300, 400, 500.

[0059] The setting value increasing process of FIG. 6 may be performed for the space heating terminals 8b, 8c other than the space heating terminal 8a. Thus, in the above description on the setting value increasing process, the thermostat 26a can be replaced with the thermostat 26b (or the thermostat 26c), the terminal pump 24a can be replaced with the terminal pump 24b (or the terminal pump 24c), and the space heating terminal 8a can be replaced with the space heating terminal 8b (or the space heating terminal 8c).

Variants

[0060] The space heating system 2 is not limited to comprising five heat source devices and may comprise two, three, four, or six or more heat source devices.

[0061] The space heating system 2 is not limited to comprising three space heating terminals and may comprise one, two, or four or more space heating terminals.

[0062] (FIG. 1) The space heating system 2 may not comprise the hot-water supply circuit 4. In this case, the heat source devices 100, 200, 300, 400, 500 may be configured not to perform the second heating operation.

[0063] (FIG. 1) An on-off valve may be disposed on each of the terminal channels 22a, 22b, 22c to open and close the terminal channels 22a, 22b, 22c. When the thermostat 26a, 26b, 26c outputs the heating ON signal, the on-off valve on the corresponding terminal channel 22a, 22b, 22c may open, allowing the heat medium to be supplied to the corresponding space heating terminal 8a, 8b, 8c. When the thermostat 26a, 26b, 26c outputs the heating OFF signal, the on-off valve on the corresponding terminal channel 22a, 22b, 22c may close, prohibiting the heat medium from being supplied to the corresponding space heating terminal 8a, 8b, 8c.

[0064] (FIG. 1) The space heating system 2 may comprise a remote controller manipulatable by a user instead of or in addition to the thermostats 26a, 26b, 26c. The user can perform input operations to start/stop the space heating by the space heating terminals 8a, 8b, 8c on the remote controller. When the input operation to start the space heating by the space heating terminal 8a, 8b, 8c is performed, the remote controller may output the heating ON signal. When the input operation to stop the space heating by the space heating terminal 8a, 8b, 8c is performed, the remote controller may output the heating OFF signal. The heating ON signal/heating OFF signal output from the remote controller may be transmitted to the heat source controller 102, 202, 302 via the first signal line 62a, 62b, 62c corresponding to the space heating terminal 8a, 8b, 8c.

[0065] (FIG. 1) Even when all the heat source devices 100, 200, 300, 400, 500 are unable to perform the first heating operation, the operations of the terminal pumps 24a, 24b, 24c may be permitted.

[0066] (FIG. 1) Not only when all the heat source devices 100, 200, 300, 400, 500 are unable to perform the first heating operation, but also when at least one (e.g., more than half) of the heat source devices 100, 200, 300, 400, 500 is unable to perform the first heating operation, the operations of the terminal pumps 24a, 24b, 24c may be prohibited.

[0067] (FIG. 4) The priorities for the first heating operation may be assigned in different ways from the embodiment. For example, the priorities may be rotated regularly (e.g., every 24 hours) among the heat source devices 100, 200, 300, 400, 500.

[0068] (FIG. 1) The space heating system 2 may further comprise a control device (termed system controller hereinafter) separate from the heat source controllers 102, 202, 302, 402, 502 and communicable with the heat source controllers 102, 202, 302, 402, 502. Instead of the parent controller 102, the system controller may perform at least a part of the heat source selecting process of FIG. 5. For example, the system controller may determine whether all the heat source devices 100, 200, 300, 400, 500 are unable to perform the first heating operation (S2). The system controller may determine the number of heat source devices that are to perform the first heating operation (S4). The system controller may select heat source device(s) that are to perform the first heating operation (S6). Instead of the parent controller 102, the system controller may perform at least a part of the setting value increasing process of FIG. 6. For example, the system controller may determine whether the first heating operation is being performed in at least one of the heat source devices 100, 200, 300, 400, 500 (S24). The system controller may perform the time measurement and determine whether the time measurement period is equal to or longer than the predetermined period (S28, S30, S32, S36).

[0069] (FIG. 6) In S34 of the setting value increasing process, the parent controller 102 may cause at least one of the heat source devices 100, 200, 300, 400, 500 to increase their output setting values.

[0070] (FIG. 6) In the setting value increasing process, S24 may be skipped and S28 may be started after S22. Thus, after the thermostat 26a has output the heating ON signal, the time measurement may be started regardless of whether the first heating operation is being performed in at least one of the heat source devices 100, 200, 300, 400, 500. That is, if the thermostat 26a has not output the heating OFF signal for a long time, the output setting values of the heat source devices 100, 200, 300, 400, 500 may be increased regardless of whether the first heating operation is being performed in at least one of the heat source devices 100, 200, 300, 400, 500.

[0071] (FIG. 1) The parent controller 102 may instruct the terminal pumps 24a, 24b, 24c to operate/stop. Specifically, when the thermostat 26a, 26b, 26c outputs the heating ON signal, the parent controller 102 may activate the corresponding terminal pump 24a, 24b, 24c. When the thermostat 26a, 26b, 26c outputs the heating OFF signal, the parent controller 102 may stop the corresponding terminal pump 24a, 24b, 24c. In this variant, the parent controller 102 can easily identify the operation states of the terminal pumps 24a, 24b, 24c.

Correspondence Relationships

[0072] The hot-water supply circuit 4 is an example of hot-water supply circuit. The space heating circuit 6 is an example of space heating circuit. The space heating terminals 8a, 8b, 8c are examples of space heating terminal. The heat source devices 100, 200, 300, 400, 500 are an example of a plurality of heat source devices. The heat source controllers 102, 202, 302, 402, 502 are an example of a plurality of heat source controllers. The thermostats 26a, 26b, 26c are examples of request generator. The heating ON signal is an example of heating request. The first signal lines 62a, 62b, 62c are examples of request transmitter. The heat source controllers 102, 202, 302 are examples of predetermined heat source controller. The heat source controller 102 is an example of selector. The heat source controller 102 is an example of parent controller. The heat source controllers 202, 302, 402, 502 are examples of child controller. The terminal pumps 24a, 24b, 24c are examples of pump.

[0073] Specific examples of the present invention have been described in detail, however, these are mere exemplary indications and thus do not limit the scope of the claims. The art described in the claims includes modifications and variations of the specific examples presented above. Technical features described in the description and the drawings may technically be useful alone or in various combinations, and are not limited to the combinations as originally claimed. Further, the art described in the description and the drawings may concurrently achieve a plurality of aims, and technical significance thereof resides in achieving any one of such aims.