Hot water heating system

Abstract

To provide a hot water heating device which prevents a water circulation circuit from freezing when an outdoor air temperature is equal to or less than a predetermined temperature, while preventing decrease of a room temperature of a room in an order at which a human does not feel the coldness.SOLUTION: If an outdoor air temperature To becomes equal to or less than a predetermined temperature Tos, when at least one of water temperatures Twi of first-third indoor terminal machines 4i (i=a-c) whose operations are stopped is equal to or less than a predetermined water temperature Tw2, or when room temperatures Tki of first-third rooms 3i are equal to or less than a predetermined room temperature Tks, an indoor open / close valve 12i of the concerned indoor terminal machine 4i is operated to be opened.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a hot water heating apparatus that prevents freezing of a water circulation circuit that flows water to a plurality of indoor terminal units during cold seasons. [Background technology]

[0002] There is a hot water heating system that provides heating by circulating water heated by a heat source unit to multiple indoor terminal units installed in multiple rooms. In this hot water heating system, if any of the indoor terminal units is not operating during the cold season, there is a risk that the water in the piping of the water circulation circuit, which is the path through which water flows to the indoor terminal unit, will freeze.

[0003] The hot water heating device in Patent Document 1 has a heat source unit that heats water, a pump, multiple indoor terminal units that are connected in parallel to the heat source unit, and a water circulation circuit in which on-off valves are connected by piping. In Patent Document 1, when the heating operation of all indoor terminal units is stopped and the outside air temperature falls below a predetermined temperature (for example, 3°C), the pump is operated and the on-off valves of all indoor terminal units are opened one by one or multiple by one in sequence, causing water to flow throughout the water circulation circuit and preventing the water in the piping of the water circulation circuit from freezing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-240381 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the hot water heating device of Patent Document 1 prevents freezing by flowing water through all indoor terminal units when the outdoor temperature falls below a predetermined temperature, so low-temperature water also flows through indoor terminal units installed in rooms where the room temperature is low enough that people do not feel cold. If low-temperature water flows through the indoor terminal unit in such a room, the room temperature will drop, and there is a risk that the room temperature will become high enough that people will feel cold.

[0006] Therefore, the present invention has been made to solve such problems, and aims to provide a hot water heating device that prevents the water circulation circuit from freezing when the outside air temperature falls below a predetermined temperature, while at the same time suppressing a drop in the room temperature in a room that is warm enough that people do not feel cold. [Means for solving the problem]

[0007] One aspect of the invention is a hot water heating device comprising a water circulation circuit in which a heat source unit for heating water, a pump, a plurality of indoor terminal units connected in parallel to the heat source unit, and a plurality of on-off valves are connected by piping, and in which water circulates between the plurality of indoor terminal units and the heat source unit; an outdoor air temperature detection means for detecting the outdoor air temperature; a plurality of terminal unit water temperature detection means for detecting the terminal unit water temperature, which is the temperature of the water flowing through each of the plurality of indoor terminal units; a plurality of room temperature detection means for detecting the room temperature of the room in which each of the plurality of indoor terminal units is installed; and an anti-freeze control means for opening the on-off valve corresponding to an indoor terminal unit that has stopped operating by closing the corresponding on-off valve, and flowing water into the indoor terminal unit to perform anti-freeze control, wherein the anti-freeze control means performs anti-freeze control on the on-off valve corresponding to an indoor terminal unit that has stopped operating and that satisfies at least one of the following: the terminal unit water temperature of the flowing water is below a first water temperature, and the room temperature of the room in which it is installed is below a predetermined temperature, when the outdoor air temperature is below a predetermined temperature. Effect of the Invention

[0008] According to the hot water heating device of the present invention, it is possible to prevent the water circulation circuit from freezing when the outside air temperature falls below a predetermined temperature, and at the same time, it is possible to suppress a drop in the room temperature in a room that is warm enough that people do not feel cold. [Brief description of the drawings]

[0009] [Figure 1] 1 is a circuit diagram showing a heat pump type hot water heating device according to the present invention. [Diagram 2]4 is a flowchart showing a main routine of anti-freeze control performed by the heat pump type hot water heating device according to the present invention. [Diagram 3] 3 is a flowchart showing a specific operation of the anti-freeze specification process in the flowchart of FIG. 2. [Figure 4] 4 is a flowchart showing a specific operation of the indoor on-off valve control process in the flowchart of FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Next, an embodiment of the present invention will be described with reference to the drawings. The embodiments shown below are examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not specify the materials, shapes, structures, arrangements, etc. of the components to be described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims. [Heat pump type hot water heating system]

[0011] FIG. 1 is a circuit diagram showing a heat pump hot water heating device 1 according to a first embodiment of the present invention.

[0012] The heat pump type hot water heating device 1 comprises an outdoor unit 2 and multiple indoor terminal units 4a, 4b, 4c (referred to as the first indoor terminal unit 4a, the second indoor terminal unit 4b, and the third indoor terminal unit 4c) installed in multiple rooms 3a, 3b, 3c (referred to as the first room 3a, the second room 3b, and the third room 3c).

[0013] The outdoor unit 2 includes a refrigerant circuit 10 formed by sequentially connecting a compressor 5, a four-way valve 6, a water-refrigerant heat exchanger 7 for exchanging heat between water and a refrigerant, an expansion valve 8, and an outdoor heat exchanger 9 with piping. The outdoor unit 2 also includes a pump 15 and a fourth water temperature sensor 21, which will be described later. The water-refrigerant heat exchanger 7 corresponds to a heat source unit of the present invention.

[0014] The first indoor terminal unit 4a has a first indoor on-off valve 12a and a first indoor heat exchanger 13a. A pump 15, the water-refrigerant heat exchanger 7, the first indoor on-off valve 12a, and the first indoor heat exchanger 13a are connected in sequence by piping to form a first water circulation circuit 16. The first indoor terminal unit 4a also has a first room temperature sensor 19a and a first water temperature sensor 20a. The first room temperature sensor 19a detects the room temperature of the first room 3a. The first water temperature sensor 20a is disposed between the pump 15 and the first indoor heat exchanger 13a of the first water circulation circuit 16 to detect the temperature of the water that has passed through the first indoor heat exchanger 13a.

[0015] The second indoor terminal unit 4b has a second indoor on-off valve 12b and a second indoor heat exchanger 13b. One end of the pipe is connected to a first water circulation circuit 16 between the water-refrigerant heat exchanger 7 and the first indoor on-off valve 12a of the first indoor terminal unit 4a, and the other end of the pipe is connected to the first water circulation circuit 16 between the pump 15 and the first indoor heat exchanger 13a of the first indoor terminal unit 4a, and the second indoor on-off valve 12b and the second indoor heat exchanger 13b are connected in series between the one end and the other end of the pipe. This forms a second water circulation circuit 17 in which the pump 15, the water-refrigerant heat exchanger 7, the second indoor on-off valve 12b, and the second indoor heat exchanger 13b are connected in sequence by piping. The second indoor terminal unit 4b also has a second room temperature sensor 19b and a second water temperature sensor 20b. The second room temperature sensor 19b detects the room temperature of the second room 3b. The second water temperature sensor 20b is disposed between the pump 15 of the second water circulation circuit 17 and the second indoor heat exchanger 13b, and detects the temperature of the water that has passed through the second indoor heat exchanger 13b.

[0016] The third indoor terminal unit 4c has a third indoor on-off valve 12c and a third indoor heat exchanger 13c. One end of the pipe is connected to a first water circulation circuit 16 between the water-refrigerant heat exchanger 7 and the first indoor on-off valve 12a of the first indoor terminal unit 4a, and the other end of the pipe is connected to the first water circulation circuit 16 between the pump 15 and the first indoor heat exchanger 13a of the first indoor terminal unit 4a, and the third indoor on-off valve 12c and the third indoor heat exchanger 13c are connected in series between the one end and the other end of the pipe. This forms a third water circulation circuit 18 in which the pump 15, the water-refrigerant heat exchanger 7, the third indoor on-off valve 12c, and the third indoor heat exchanger 13c are connected in sequence by piping. The third indoor terminal unit 4c also has a third room temperature sensor 19c and a third water temperature sensor 20c. The third room temperature sensor 19c detects the room temperature of the third room 3c. The third water temperature sensor 20c is disposed between the pump 15 of the third water circulation circuit 18 and the third indoor heat exchanger 13c, and detects the temperature of water that has passed through the third indoor heat exchanger 13c.

[0017] As a result, the first indoor terminal unit 4a and the first indoor opening / closing valve 12a connected to the first water circulation circuit 16, the second indoor terminal unit 4b and the second indoor opening / closing valve 12b connected to the second water circulation circuit 17, and the third indoor terminal unit 4c and the third indoor opening / closing valve 12c connected to the third water circulation circuit 18 are connected in parallel to the water-refrigerant heat exchanger 7. Furthermore, a fourth water temperature sensor 21 is disposed between the water-refrigerant heat exchanger 7 of the first water circulation circuit 16 and the first indoor on-off valve 12a, for detecting the temperature of the water that passes through the water-refrigerant heat exchanger 7 and before it branches into the second water circulation circuit 17 and the third water circulation circuit 18. And, an outside air temperature sensor 22 is disposed outside the room, for detecting the outside air temperature.

[0018] The first indoor terminal unit 4a to the third indoor terminal unit 4c correspond to the indoor terminal unit of the present invention, and the first water circulation circuit 16 to the third water circulation circuit 18 correspond to the water circulation circuit of the present invention. The first room temperature sensor 19a to the third room temperature sensor 19c correspond to the room temperature detection means of the present invention, the first water temperature sensor 20a to the third water temperature sensor 20c correspond to the terminal unit water temperature detection means of the present invention, the fourth water temperature sensor 21 corresponds to the heat source unit water temperature detection means of the present invention, and the outdoor air temperature sensor 22 corresponds to the outdoor air temperature detection means of the present invention.

[0019] When the first indoor on-off valve 12a of the first indoor terminal unit 4a is opened and the pump 15 is driven, water circulates through the first water circulation circuit 16, water is supplied to the first indoor heat exchanger 13a of the first indoor terminal unit 4a, and water returns from the first indoor heat exchanger 13a to the water-refrigerant heat exchanger 7. Similarly, when the second indoor on-off valve 12b of the second indoor terminal unit 4b is opened and the pump 15 is driven, water circulates through the second water circulation circuit 17, water is supplied to the second indoor heat exchanger 13b of the second indoor terminal unit 4b, and water returns from the second indoor heat exchanger 13b to the water-refrigerant heat exchanger 7. Similarly, when the third indoor on-off valve 12c of the third indoor terminal unit 4c opens and the pump 15 is driven, water circulates through the third water circulation circuit 18, water is supplied to the third indoor heat exchanger 13c of the third indoor terminal unit 4c, and water returns from the third indoor heat exchanger 13c to the water-refrigerant heat exchanger 7. In addition, when the first indoor opening / closing valve 12a of the first indoor terminal unit 4a, the second indoor opening / closing valve 12b of the second indoor terminal unit 4b, and the third indoor opening / closing valve 12c of the third indoor terminal unit 4c are all opened and the pump 15 is driven, water circulates through the first water circulation circuit 16, the second water circulation circuit 17, and the third water circulation circuit 18, and water is supplied in parallel to the first indoor heat exchanger 13a of the first indoor terminal unit 4a, the second indoor heat exchanger 13b of the second indoor terminal unit 4b, and the third indoor heat exchanger 13c of the third indoor terminal unit 4c, and water returns to the water-refrigerant heat exchanger 7 from these first indoor heat exchangers 13a to third indoor heat exchangers 13c.

[0020] The heat pump type hot water heating device 1 of this embodiment is equipped with a control means 25 that controls each device. That is, the control means 25 performs various controls related to the operation of the heat pump type hot water heating device 1, such as drive control of the compressor 5, switching control of the four-way valve 6, opening control of the expansion valve 8, drive control of the pump 15, and opening and closing control of the first indoor opening and closing valve 12a to the third indoor opening and closing valve 12c, based on the detection values ​​detected by the first room temperature sensor 19a to the third room temperature sensor 19c, the first water temperature sensor 20a to the third water temperature sensor 20c, the fourth water temperature sensor 21, and the outside air temperature sensor 22. The control means 25 also includes a timer unit that measures time, and a storage unit that stores a control program for the heat pump type hot water heating device 1.

[0021] 1, the control means 25 of the heat pump type hot water heating device 1 of this embodiment has a freeze prevention control means 26. The freeze prevention control means 26 can be realized by software as a function that the control means 25 has.

[0022] In the heat pump type hot water heating device 1 of this embodiment, when the heating operation of the outdoor unit 2, the first indoor terminal unit 4a installed in the first room 3a, the second indoor terminal unit 4b installed in the second room 3b, and the third indoor terminal unit 4c installed in the third room 3c is stopped, the anti-freeze control is automatically started. Note that the first indoor opening / closing valve 12a of the first indoor terminal unit 4a, the second indoor terminal unit 4b, and the third indoor opening / closing valve 12 of the third indoor terminal unit 4c are closed when the heating operation is stopped. [Anti-freeze control]

[0023] Next, the anti-freeze control performed by the anti-freeze control means 26 in the heat pump type hot water heating device 1 of this embodiment will be described with reference to Fig. 2 to Fig. 4. Fig. 2 shows a main routine of the anti-freeze control, Fig. 3 shows an indoor terminal device identification process included in the main routine of Fig. 2, and Fig. 4 shows an indoor opening / closing valve control process included in the indoor terminal device identification process of Fig. 3.

[0024] First, in step ST1 in Fig. 2, it is determined whether or not the stop time (pump stop time) PT of the pump 15 is equal to or longer than a first set time PTs (e.g., 3 hours). Here, the first set time PTs is set to a time at which it is considered that the water in the water circulation circuit will not freeze even if anti-freeze control is not performed. If it is determined that the pump stop time PT is equal to or longer than the first set time PTs (step ST1: YES), the process proceeds to step ST2, and if the pump stop time PT is shorter than the first set time PTs (step ST1: NO), step ST1 is repeated. In step ST2, the outside air temperature To detected by the outside air temperature sensor 22 is read.

[0025] Next, in step ST3, it is determined whether the outside air temperature To is equal to or lower than a predetermined temperature Tos (e.g., 5°C). Here, the predetermined temperature Tos is set to a temperature at which the water in the water circulation circuit is not considered to freeze. If it is determined that the outside air temperature To is equal to or lower than the predetermined temperature Tos (step ST3: YES), the process proceeds to step ST4, and if the outside air temperature To is higher than the predetermined temperature Tos (step ST3: NO), the process proceeds to step ST1. In step ST4, the pump 15 starts to be driven.

[0026] Next, in step ST5, the first indoor opening / closing valve 12a of the first indoor terminal unit 4a, the second indoor opening / closing valve 12b of the second indoor terminal unit 4b, and the third indoor opening / closing valve 12c of the third indoor terminal unit 4c are opened.

[0027] Next, in step ST6, it is determined whether or not a second set time Nv1 (e.g., 15 minutes) has elapsed since the opening operation of the first indoor on-off valve 12a to the third indoor on-off valve 12c. Here, the second set time Nv1 is set to a time sufficient for a local temperature drop in the water circulation circuit to be eliminated. Note that the second set time Nv1 corresponds to a predetermined time during which the freeze prevention control means in the present invention opens the on-off valves of all indoor terminal units and controls the drive of the pump before performing freeze prevention control. If the second set time Nv1 has elapsed (step ST6: YES), the process proceeds to step ST7, and if the second set time Nv1 has not elapsed (step ST6: NO), ST6 is repeated. In step ST7, the first indoor on-off valve 12a to the third indoor on-off valve 12c are closed.

[0028] Next, in step ST8, the water temperature Twa detected by the first water temperature sensor 20a, the water temperature Twb detected by the second water temperature sensor 20b, and the water temperature Twc detected by the third water temperature sensor 20c are read. Next, in step ST9, the water temperature Twd detected by the fourth water temperature sensor 21 is read. Note that the water temperatures Twa, Twb, and Twc correspond to the terminal device water temperature of the present invention, and the water temperature Twd corresponds to the heat source device water temperature of the present invention.

[0029] Next, in step ST10, it is determined whether at least one of the water temperatures Twa, Twb, Twc, and Twd is equal to or lower than a predetermined water temperature Tw1. Here, the predetermined water temperature Tw1 is a temperature determined taking into consideration the possibility of water freezing, and is set to, for example, 0°C, which is the freezing point of water. In order to further reduce the possibility of water freezing, the predetermined water temperature Tw1 may be set to 2°C above the freezing point of water, providing a margin of safety for low possibility of water freezing. The predetermined water temperature Tw1 corresponds to the second water temperature of the present invention.

[0030] If it is determined in step ST10 that at least one of the water temperatures Twa, Twb, Twc, and Twd is below the predetermined water temperature Tw1 (step ST10: YES), the process proceeds to step ST11, and if all of the water temperatures Twa, Twb, Twc, and Twd are above the predetermined water temperature Tw1 (step ST10: NO), the main routine is terminated.

[0031] In step ST11, the antifreeze specific process shown in FIG. 3 is carried out.

[0032] In the freeze prevention specific process in Fig. 3, the subscript i of the process flag Fi is one of a, b, and c. That is, the process flag Fa indicates the process flag of the first indoor terminal unit 4a, the process flag Fb indicates the process flag of the first indoor terminal unit 4b, and the process flag Fc indicates the process flag of the third indoor terminal unit 4c (hereinafter, the subscript i may be used to indicate the water temperatures Twa, Twb, and Twc as the water temperatures Twi, the first indoor terminal unit 4a to the third indoor terminal unit 4c as the indoor terminal unit 4i, the room temperatures Tka, Tkb, and Tkc as the room temperatures Tki, the first indoor opening / closing valve 12a to the third indoor opening / closing valve 12c as the indoor opening / closing valve 12i, the first room temperature sensor 19a to the third room temperature sensor 19c as the room temperature sensor 19i, and the first room 3a to the third room 3c as the room 3i). Fa="0" indicates that the first indoor terminal unit 4a has not undergone antifreeze processing, Fa="1" indicates that the first indoor terminal unit 4a has not yet undergone antifreeze processing, and Fa="2" indicates that the first indoor terminal unit 4a has undergone antifreeze processing. The processing flag Fb is the processing flag of the second indoor terminal unit 4b, Fb="0" indicates that the second indoor terminal unit 4b has not undergone antifreeze processing, Fb="1" indicates that the second indoor terminal unit 4b has not yet undergone antifreeze processing, and Fb="2" indicates that the second indoor terminal unit 4b has undergone antifreeze processing. The processing flag Fc is the processing flag of the third indoor terminal unit 4c, Fc="0" indicates that the third indoor terminal unit 4c has not undergone antifreeze processing, Fc="1" indicates that the third indoor terminal unit 4c has not yet undergone antifreeze processing, and Fc="2" indicates that the third indoor terminal unit 4c has undergone antifreeze processing. In this antifreeze specific process, in step ST12 of FIG. 3, the process flags Fa, Fb, and Fc are set to "0."

[0033] Next, in step ST13, the room temperature Tka detected by the first room temperature sensor 19a, the room temperature Tkb detected by the second room temperature sensor 19b, and the room temperature Tkc detected by the third room temperature sensor 19c are read.

[0034] Next, in step ST14, it is determined whether at least one of the water temperature Twa detected by the first water temperature sensor 20a, the water temperature Twb detected by the second water temperature sensor 20b, and the water temperature Twc detected by the third water temperature sensor 20c is equal to or lower than the predetermined water temperature Tw2. If at least one of the water temperatures Twa, Twb, and Twc is equal to or lower than the predetermined water temperature Tw2 (step ST14: YES), the process proceeds to step ST15. If all of the water temperatures Twa, Twb, and Twc are higher than the predetermined water temperature Tw2 (step ST14: NO), the process proceeds to step ST16. Here, the predetermined water temperature Tw2 is a temperature determined in consideration of the possibility that water may freeze, and may be the same temperature as the predetermined water temperature Tw1, or may be a temperature with a larger margin than the predetermined water temperature Tw1. In other words, the predetermined water temperature Tw1 is equal to or lower than the predetermined water temperature Tw2. The predetermined water temperature Tw2 corresponds to the first water temperature of the present invention.

[0035] In step ST16, it is determined whether at least one of the room temperature Tka detected by the first room temperature sensor 19a, the room temperature Tkb detected by the second room temperature sensor 19b, and the room temperature Tkc detected by the third room temperature sensor 19c is equal to or lower than a predetermined room temperature Tks. Note that the predetermined room temperature Tks corresponds to a predetermined temperature that is compared with the room temperature Tka detected by the first room temperature sensor 19a, the room temperature Tkb detected by the second room temperature sensor 19b, and the room temperature Tkc detected by the third room temperature sensor 19c in order for the freeze prevention control means in the present invention to determine the indoor opening / closing valve for performing freeze prevention control. If this determination determines that at least one of room temperature Tka, room temperature Tkb, and room temperature Tkc is below the specified room temperature Tks (step ST16: YES), proceed to step ST15; if all of room temperature Tka, room temperature Tkb, and room temperature Tkc are above the specified room temperature Tks (step ST16: NO), proceed to step ST25.

[0036] In step ST15, the processing flag Fi of the indoor terminal unit 4i whose water temperature Twi is equal to or lower than the predetermined room temperature Tks, or whose room temperature Tki is equal to or lower than the predetermined room temperature Tks, is set to "1". Specifically, in step ST14, if at least one of the water temperature Twa, water temperature Twb, and water temperature Twc is equal to or lower than the predetermined water temperature Tw2 and the process proceeds to step ST15, the processing flag Fi of the indoor terminal unit 4i whose water temperature Twi is equal to or lower than the predetermined room temperature Tks is set to "1". In addition, in step ST16, if at least one of the room temperature Tka, room temperature Tkb, and room temperature Tkc is equal to or lower than the predetermined room temperature Tks and the process proceeds to step ST15, the processing flag Fi of the indoor terminal unit 4i whose room temperature Tki is equal to or lower than the predetermined room temperature Tks is set to "1".

[0037] Next, in step ST17, it is determined whether at least one of the processing flags Fa of the first indoor terminal unit 4a, Fb of the second indoor terminal unit 4b, and Fc of the third indoor terminal unit 4c is "1." If it is determined that at least one of the processing flags Fa, Fb, and Fc is "1" (step ST17: YES), the process proceeds to step ST18. On the other hand, if none of the processing flags Fa, Fb, and Fc is "1," that is, if all of the processing flags Fa, Fb, and Fc are "0" or "2" (step ST17: NO), the process proceeds to step ST25.

[0038] In step ST18, it is determined whether or not there are multiple processing flags Fa, Fb, Fc set to "1." If there are multiple processing flags Fa, Fb, Fc set to "1" (step ST18: YES), the process proceeds to step ST19, and if there is only one processing flag Fa, Fb, Fc set to "1" (step ST18: NO), the process proceeds to step ST20.

[0039] In step ST19, when there are multiple indoor terminal units 4i that should undergo antifreeze processing, the indoor terminal unit that should undergo antifreeze processing is identified as the one that should undergo antifreeze processing. In step ST14, when at least one of the water temperatures Twa, Twb, and Twc is equal to or lower than the predetermined water temperature Tw2 and the process proceeds to step ST15, the indoor terminal unit 4i with the lowest water temperature Twi among the multiple indoor terminal units is identified as the indoor terminal unit that should undergo antifreeze processing. In addition, in step ST16, when at least one of the room temperatures Tka, Tkb, and Tkc is equal to or lower than the predetermined room temperature Tks and the process proceeds to step ST15, the indoor terminal unit 4i with the lowest room temperature Tki among the multiple indoor terminal units is identified as the indoor terminal unit that should undergo antifreeze processing.

[0040] On the other hand, in step ST20, since there is only one indoor terminal unit 4i for which the anti-freezing process should be performed, that indoor terminal unit is specified as the indoor terminal unit for which the anti-freezing process should be preferentially performed.

[0041] Next, in step ST21, the indoor on-off valve control process shown in FIG. 4 is performed.

[0042] In this indoor on-off valve control process, first, in step ST30 of FIG. 4, the indoor on-off valve 12i of the identified indoor terminal unit 4i is opened to allow water to flow through the indoor terminal unit 4i.

[0043] Next, in step ST31, the room temperature Tki detected by the room temperature sensor 19i of the identified indoor terminal unit 4i is read. Next, in step ST32, it is determined whether or not a predetermined room temperature measurement time n1 (e.g., 60 seconds) has elapsed since the room temperature Tki was read. If the room temperature measurement time n1 has elapsed (step ST32: YES), the process proceeds to step ST33, and if the room temperature measurement time n1 has not elapsed (step ST32: NO), ST32 is repeated. In step ST33, the room temperature Tki detected by the room temperature sensor 19i is read. Next, in step ST34, the room temperature Tki at the start of measurement is read. 0 From current room temperature Tki nThe amount of room temperature drop per unit time, ΔT, is calculated by dividing the amount of room temperature drop by the room temperature measurement time n1.

[0044] Next, in step ST35, it is determined whether the amount of decrease in room temperature ΔT per unit time is equal to or greater than the decrease threshold, or whether the third set time Nv2 (e.g., 15 minutes) has elapsed since the opening operation of the indoor opening / closing valve 12i. If the amount of decrease in room temperature ΔT per unit time is equal to or greater than the decrease threshold, or the third set time Nv2 has elapsed since the opening operation of the indoor opening / closing valve 12i (step ST35: YES), the process proceeds to step ST36. If the amount of decrease in room temperature ΔT per unit time is less than the decrease threshold, and the third set time Nv2 has not elapsed since the opening operation of the indoor opening / closing valve 12i (step ST35: NO), the process proceeds to step ST31.

[0045] In step ST36, the indoor on-off valve 12i is closed, and then the indoor on-off valve control process is terminated, and the process returns to the indoor terminal unit identification process in FIG. 3, where the process of step ST22 is executed.

[0046] In step ST22 of FIG. 3, the processing flag Fi of the indoor terminal unit 4i is set to "2," and the indoor terminal unit 4i is deemed to have completed the anti-freezing process.

[0047] Next, in step ST23, the outside air temperature To detected by the outside air temperature sensor 22 is read.

[0048] Next, in step ST24, it is determined whether the outside air temperature To is equal to or lower than a predetermined temperature Tos. If the outside air temperature To is equal to or lower than the predetermined temperature Tos (step ST24: YES), the process proceeds to step ST17. If the outside air temperature To is higher than the predetermined temperature Tos (step ST24: NO), the process proceeds to step ST25.

[0049] In step ST25, the driving of the pump 15 is stopped, and then the process returns to the main routine of FIG. 2, whereupon the process of the main routine ends. [Function of the anti-freezing control method for heat pump hot water heating equipment]

[0050] Next, the action of the anti-freeze control performed by the anti-freeze control means 26 in the heat pump hot water heating device 1 will be described with reference to Figs.

[0051] When the outdoor temperature To becomes equal to or lower than the predetermined temperature Tos, if at least one of the water temperatures Twi of the indoor terminal units 4i that are not in operation is equal to or lower than the predetermined water temperature Tw2 (step ST14 in FIG. 3: YES), or if at least one of the room temperatures Tki of the rooms 3i is equal to or lower than the predetermined room temperature Tks (step ST16 in FIG. 3: YES), the indoor opening / closing valve 12i of the corresponding indoor terminal unit 4i opens, and water flows into the indoor terminal unit 4i (step ST30 in FIG. 4). For example, in this embodiment, if the water temperature Twa of the first indoor terminal unit 4a is equal to or lower than the predetermined water temperature Tw2, the room temperature Tkb of the second indoor terminal unit 4b is equal to or lower than the predetermined room temperature Tks, the water temperature Twc of the third indoor terminal unit 4c exceeds the predetermined water temperature Tw2, and the room temperature Tkc is also equal to or higher than the predetermined room temperature Tks, the first indoor opening / closing valve 12a of the first indoor terminal unit 4a and the second indoor opening / closing valve 12b of the second indoor terminal unit 4a are opened to perform anti-freezing control for the third set time Nv2. By performing the anti-freeze control in this manner, even if the outside air temperature To is equal to or lower than the predetermined temperature Tos, water is circulated to the first water circulation circuit 16 and the second water circulation circuit 17, thereby preventing the water in the water circulation circuit from freezing. Furthermore, since the heating operation is stopped and the room temperature Tkc is higher than the predetermined room temperature Tks, it is considered that the room temperature in the third room 3c is low enough that people do not feel cold, but since the anti-freeze control of the third indoor opening / closing valve 12c installed in the third room 3c is not performed and the drop in the room temperature in the third room 3c is suppressed, people using the third room 3c do not feel uncomfortable.

[0052] Furthermore, when there are multiple indoor terminal units 4i for which anti-freezing control is to be performed, anti-freezing control is performed for each of the multiple indoor terminal units 4i in sequence (steps ST17 to ST24 in FIG. 3 are repeated). In this manner, it is possible to prevent a significant drop in the room temperature of a specific room among the first room 3a to the third room 3c, and it is possible to maintain the comfort of the users in the first room 3a to the third room 3c. Furthermore, since anti-freezing control is performed for each room in sequence, it is possible to minimize the number of rooms whose room temperatures drop. In addition, when performing anti-freezing control for the indoor terminal units 4i in sequence, the anti-freezing control is performed in sequence starting from the indoor terminal unit with the lowest water temperature Twi or the indoor terminal unit with the lowest room temperature Tki (step ST19 in FIG. 3). For example, in this embodiment, when the water temperature Twa of the first indoor terminal unit 4a and the water temperature Twb of the second indoor terminal unit 4b are equal to or lower than the predetermined water temperature Tw2, if the water temperature Twa of the first indoor terminal unit 4a is lower than the water temperature Twb of the second indoor terminal unit 4b, the anti-freezing control of the first indoor terminal unit 4a is started first. In this way, the anti-freezing control is performed with priority on the first water circulation circuit 16 that is at risk of freezing, so that anti-freezing can be reliably performed.

[0053] Furthermore, even if the outside air temperature To is below a predetermined temperature Tos, anti-freeze control is not performed if the water temperature Twa of the first indoor terminal unit 4a, the water temperature Twb of the second indoor terminal unit 4b, the water temperature Twc of the third indoor terminal unit 4c, and the water temperature Twd of the water-refrigerant heat exchanger 7 exceed the predetermined water temperature Tw1, which is a water temperature at which freezing may occur (step ST10: NO in Figure 2).Even if the outside air temperature is low, anti-freeze control is not performed if the water temperature is high and there is little risk of freezing, so that the drop in room temperatures in the first room 3a to the third room 3c is suppressed, thereby maintaining the comfort of users in the first room 3a to the third room 3c.

[0054] In addition, when the rate of decrease per unit time of the room temperature of the room 3i in which the indoor terminal unit 4i performing the anti-freeze control is installed reaches or exceeds a threshold amount of decrease, the anti-freeze control is stopped (steps ST35 and ST36 in FIG. 4). When the room temperature of the room 3i drops suddenly, the anti-freeze control is stopped to prevent a further decrease in the room temperature of the room 3i, thereby maintaining the comfort of the user in the room 3i.

[0055] Furthermore, before performing the freeze prevention control, the first indoor opening / closing valve 12a of the first indoor terminal unit 4a, the first indoor opening / closing valve 12b of the second indoor terminal unit 4b, and the third indoor opening / closing valve 12c of the third indoor terminal unit 4c are opened for the second set time Nv1 to control the driving of the pump 15, and water is circulated throughout the first water circulation circuit 16 to the third water circulation circuit 18 (steps ST4 to ST7 in FIG. 2). This makes it possible to reliably avoid the risk of freezing even if there are any locations among the first water circulation circuit 16 to the third water circulation circuit 18 that are at risk of freezing other than the locations where the water temperature sensors 20a to 20c detect the water temperature.

[0056] In this embodiment, the heat pump type hot water heating system 1 has been described as having a water-refrigerant heat exchanger 7 that exchanges heat between water and a refrigerant. However, the same effects can be obtained by heating water in a boiler instead of the water-refrigerant heat exchanger 7. In the present embodiment, when at least one of the water temperatures Twa, Twb, and Twc is equal to or lower than the predetermined water temperature Tw2, the anti-freezing control is performed on the indoor opening / closing valve 12i corresponding to the indoor terminal unit 4i whose water temperature Twi is equal to or lower than the predetermined room temperature Tks, and when all of the water temperatures Twa, Twb, and Twc exceed the predetermined water temperature Tw2 and at least one of the room temperatures Tka, Tkb, and Tkc is equal to or lower than the predetermined room temperature Tks, the anti-freezing control is performed on the indoor opening / closing valve 12i corresponding to the indoor terminal unit 4i whose room temperature Tki is equal to or lower than the predetermined room temperature Tks, but the present invention is not limited to this. For example, regardless of whether at least one of the water temperatures Twa, Twb, and Twc is equal to or lower than the predetermined water temperature Tw2, the anti-freezing control may be performed on the indoor opening / closing valve 12i corresponding to the indoor terminal unit 4i whose room temperature Tki is equal to or lower than the predetermined room temperature Tks. Alternatively, the freeze prevention control may be performed on the indoor opening / closing valve 12i corresponding to the indoor terminal unit 4i in which the water temperature Twi is equal to or lower than the predetermined room temperature Tks and the room temperature Tki is equal to or lower than the predetermined room temperature Tks. In addition, in this embodiment, when there are multiple indoor terminal units 4i that perform anti-freezing control, the anti-freezing control is performed for each of the multiple indoor terminal units 4i in sequence, but the anti-freezing control may be performed for multiple indoor terminal units 4i at a time. For example, when there are four or more indoor terminal units 4i, the indoor terminal unit with the lowest water temperature Twi and the indoor terminal unit with the second lowest water temperature Twi may be specified as the indoor terminal units that are given priority for anti-freezing control, and the anti-freezing control may be performed for each of the indoor terminal units. [Explanation of symbols]

[0057] 1. Heat pump type hot water heating system 2 Outdoor unit 3a Room 1 3b Room 2 3c Room 3 4a 1st indoor terminal 4b 2nd indoor terminal 4c 3rd indoor terminal 5. Compressor 6 Four-way valve 7 Water refrigerant heat exchanger 8 Expansion valve 9 Outdoor heat exchanger 10 Refrigerant circuit 12a First indoor opening and closing valve 12b Second indoor opening / closing valve 12c Third indoor opening / closing valve 13a 1st indoor heat exchanger 13b 2nd indoor heat exchanger 13c 3rd indoor heat exchanger 15 Pump 16 1st water circulation circuit 17 Second water circulation circuit 18 Third water circulation circuit 19a No. 1 room temperature sensor 19b Second room temperature sensor 19c 3rd room temperature sensor 20a No. 1 water temperature sensor 20b Second water temperature sensor 20c 3rd water temperature sensor 21 4th water temperature sensor 22 Outside air temperature sensor 25 Control Means 26 Anti-freeze control measures

Claims

1. a water circulation circuit in which a heat source unit for heating water, a pump, a plurality of indoor terminal units connected in parallel to the heat source unit, and a plurality of on-off valves are connected by piping, and water circulates between the indoor terminal units and the heat source unit; An outside air temperature detection means for detecting an outside air temperature; A plurality of terminal water temperature detection means for detecting the water temperatures of the plurality of indoor terminals; a plurality of room temperature detection means for detecting room temperatures in the rooms in which the plurality of indoor terminals are installed; and a freeze prevention control means for opening the on-off valve corresponding to the indoor terminal unit that has been stopped by closing the corresponding on-off valve, and flowing water into the indoor terminal unit to perform freeze prevention control, the anti-freezing control means, when the outdoor temperature is equal to or lower than a predetermined temperature, performs the anti-freezing control on the on-off valve corresponding to the indoor terminal that satisfies at least one of the following conditions: the water temperature of the indoor terminal is equal to or lower than a first water temperature, and the room temperature of the room in which the indoor terminal is installed is equal to or lower than a predetermined temperature, among the indoor terminals that are stopped in operation; When there are a plurality of indoor terminals that perform the anti-freezing control, the anti-freezing control means sequentially performs the anti-freezing control on the plurality of indoor terminals, and The hot water heating device is characterized in that the anti-freeze control means performs the anti-freeze control on the multiple indoor terminal units performing the anti-freeze control in order of priority, starting with the indoor terminal unit with the lowest water temperature or the indoor terminal unit with the lowest room temperature in the room in which it is installed.

2. a water circulation circuit in which a heat source unit for heating water, a pump, a plurality of indoor terminal units connected in parallel to the heat source unit, and a plurality of on-off valves are connected by piping, and water circulates between the indoor terminal units and the heat source unit; An outside air temperature detection means for detecting an outside air temperature; A plurality of terminal water temperature detection means for detecting the water temperatures of the plurality of indoor terminals; a plurality of room temperature detection means for detecting room temperatures in the rooms in which the plurality of indoor terminals are installed; a freeze prevention control means for opening the on-off valve corresponding to the indoor terminal unit that has been stopped by closing the corresponding on-off valve, and flowing water into the indoor terminal unit to perform freeze prevention control; A heat source unit water temperature detection means for detecting the water temperature of the heat source unit is provided. The hot water heating device is characterized in that the anti-freeze control means performs the anti-freeze control on the opening / closing valve corresponding to an indoor terminal unit that satisfies at least one of the following conditions: the water temperature of the indoor terminal unit is below the first water temperature and the room temperature of the room in which it is installed is below a predetermined temperature, when the heating operation of all of the indoor terminal units is stopped and at least one of the water temperatures of the heat source unit and the plurality of indoor terminal units is below a second water temperature that is below a first water temperature, and when the outside air temperature is below a predetermined temperature.

3. a water circulation circuit in which a heat source unit for heating water, a pump, a plurality of indoor terminal units connected in parallel to the heat source unit, and a plurality of on-off valves are connected by piping, and water circulates between the indoor terminal units and the heat source unit; An outside air temperature detection means for detecting an outside air temperature; A plurality of terminal water temperature detection means for detecting the water temperatures of the plurality of indoor terminals; a plurality of room temperature detection means for detecting room temperatures in the rooms in which the plurality of indoor terminals are installed; and a freeze prevention control means for opening the on-off valve corresponding to the indoor terminal unit that has been stopped by closing the corresponding on-off valve, and flowing water into the indoor terminal unit to perform freeze prevention control, When the outdoor temperature is equal to or lower than a predetermined temperature, the freeze prevention control means performs the freeze prevention control on the on-off valve corresponding to the indoor terminal that satisfies at least one of the following conditions: the water temperature of the indoor terminal is equal to or lower than a first water temperature, and the room temperature of the room in which the indoor terminal is installed is equal to or lower than a predetermined temperature, among the indoor terminals that are not in operation; The hot water heating device is characterized in that the anti-freeze control means stops the anti-freeze control when the amount of decrease per unit time of the room temperature in the room in which the indoor terminal device performing the anti-freeze control is installed becomes equal to or greater than a decrease amount threshold.

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