JP7524107B2 - Hot water heating system - Google Patents

Description

This invention relates to a hot water heating system that heats a space to be air-conditioned by heat exchange between indoor air and a circulating liquid.

Conventionally, in this type of hot water heating system, as described in Patent Document 1, the refrigerant that has exchanged heat with the outside air in the outdoor heat exchanger of the outdoor unit is guided to a liquid refrigerant heat exchanger, and the circulating liquid that has received heat from the refrigerant in the liquid refrigerant heat exchanger is supplied to the indoor heat exchanger of the fan coil unit (indoor air conditioner) via the circulating liquid piping, thereby performing a heating operation to heat the indoor air.

JP 2020-159663 A

In the conventional configuration described above, when the remote control is operated, a corresponding control signal is sent to the fan coil unit, and in response to this, a predetermined communication is made from the fan coil unit to the outdoor unit, thereby starting the heating operation. That is, the compressor is driven in the outdoor unit, whereby the refrigerant that has exchanged heat with the outside air in the outdoor heat exchanger as described above is guided to the liquid refrigerant heat exchanger, and the circulating fluid that has received heat from the refrigerant in the liquid refrigerant heat exchanger is guided to the fan coil unit via the circulating fluid piping. At this time, the open/close valve in the fan coil unit is opened by a control signal based on the remote control operation, whereby the circulating fluid that has received heat as described above is supplied to the indoor heat exchanger in the fan coil unit. As a result, heat exchange between the heated circulating fluid and the indoor air is performed in the indoor heat exchanger, and the indoor air is heated by the warm air induced by the blower fan provided in the fan coil unit.

When such a fan coil unit is used in, for example, a very cold region, a specific freeze prevention operation is generally performed in the outdoor unit to prevent the circulating liquid from freezing when the unit is not in operation during the winter. When this freeze prevention operation is performed, the circulating pump and the compressor are started in the outdoor unit, and heat is dissipated from the refrigerant to the circulating liquid in the liquid refrigerant heat exchanger.

During freeze prevention operation as described above, it is possible that due to some reason, such as a malfunction inside the outdoor unit, the circulating fluid will not be heated as described above and will instead be circulated through the circulating fluid piping by the circulating pump. In this case, the circulating fluid will continue to flow at a low temperature through the fan coil unit, causing condensation inside the fan coil unit's on-off valve, which may cause a malfunction.

In order to solve the above problem, in claim 1 of the present invention, there is provided a hot water heating system comprising: a fan coil unit including an indoor heat exchanger that performs heat exchange between indoor air in a space to be air-conditioned and a circulating fluid, a blower fan for performing the heat exchange in the indoor heat exchanger, a sensor that detects the temperature of the circulating fluid flowing through the indoor heat exchanger, an on-off valve that can open and close a flow passage of the circulating fluid, and a terminal control unit that controls the on-off valve and the blower fan; an outdoor unit including a heating heat exchanger that has a circulating fluid passage and heats the circulating fluid in the circulating fluid passage with a heat source, a circulating pump that circulates the circulating fluid, and a heat source control unit that controls the heat source and the circulating pump; and a first terminal control line that performs one-way communication from the terminal control unit to the heat source control unit, wherein the circulating fluid passage of the heating heat exchanger and the indoor heat exchanger are connected in a ring shape by a circulating fluid piping to form a liquid circulation circuit, and the hot water heating system is capable of performing a heating operation in which the indoor air is heated by the fan coil unit, and a second terminal control line connected to the heat source control unit and a second terminal control line connected to the heat source control unit, the heat source control unit having a freeze prevention control means for performing a freeze prevention operation in which the heat source is activated and the circulation pump is activated to circulate the circulating liquid through the circulating liquid piping when the heating operation is not being performed, and the terminal control unit has a first opening/closing control means for controlling to open the on-off valve based on a valve control signal from a remote control for operating the fan coil unit or from the heat source control unit via the second terminal control line, a first determination means for determining whether or not a predetermined first temperature condition is satisfied after the on-off valve is opened by the first opening/closing control means based on the valve control signal in response to execution of the freeze prevention operation by the freeze prevention control means of the heat source control unit, and a second opening/closing control means for performing at least a process of forcibly controlling the on-off valve to close by forced control of the on-off valve executed in place of the opening control by the first opening/closing control means based on the valve control signal when the first temperature condition in the first determination means is not satisfied.

In addition, in claim 2, the first temperature condition is that the circulating fluid temperature detected by the sensor is equal to or higher than a first threshold value when a first predetermined time has elapsed after the first opening/closing control means opens the opening/closing valve based on the valve control signal.

In addition, in claim 3, the terminal control unit further has a second judgment means for judging whether or not a predetermined second temperature condition is satisfied after the first temperature condition in the first judgment means is not satisfied and the second opening/closing control means controls the opening/ closing valve to close by the forced control .

In a fourth aspect of the present invention, the second temperature condition is that, after the first temperature condition in the first determination means is not satisfied and the second opening/closing control means controls the opening/ closing valve by the forced control , a second predetermined time has elapsed and the second opening/closing control means controls the opening/closing valve by the forced control , and when a third predetermined time has elapsed thereafter, the circulating fluid temperature detected by the sensor becomes equal to or higher than a second threshold value.

In addition, in claim 5, when the second temperature condition in the second judgment means is satisfied, the second opening/closing control means terminates the forced control in response to the valve control signal from the remote control or the valve control signal input from the heat source control unit via the second terminal control line corresponding to the termination of the anti-freeze operation by the anti-freeze control means.

In a sixth aspect of the present invention, when the second temperature condition in the second determination means is not satisfied, the second opening/closing control means terminates the forced control in response to the valve control signal from the remote control.

According to claim 1 of the present invention, the outdoor unit includes a heat source and a heating heat exchanger, and a circulating fluid pipe is connected to the heating heat exchanger, and the circulating fluid pipe is connected to the circulating pump and the indoor heat exchanger of the fan coil unit. During heating operation, a valve control signal is sent to the terminal control unit of the fan coil unit by operating the remote control, and a predetermined communication (one-way communication) is performed from the terminal control unit to the heat source control unit in response to the valve control signal, thereby starting the heating operation. That is, in the outdoor unit, the heat source is started by the control of the heat source control unit, and the circulating fluid that has received heat from the heat source is led to the fan coil unit through the circulating fluid pipe. At this time, the opening and closing valve in the fan coil unit is opened by the first opening and closing control means of the terminal control unit based on the valve control signal based on the remote control operation, and the circulating fluid that has received heat as described above is supplied to the indoor heat exchanger in the fan coil unit. As a result, heat exchange between the heated circulating fluid and the indoor air is performed in the indoor heat exchanger, and the indoor air is heated by the warm air induced by the blower fan based on the control of the terminal control unit.

On the other hand, in the present invention, a predetermined antifreeze operation is performed in the outdoor unit to prevent the circulating fluid from freezing when the unit is not in operation in winter. To this end, the heat source control unit is provided with antifreeze control means, and the circulating pump and the heat source are started under the control of this antifreeze control means, and heat is released from the heat source to the circulating fluid in the heating heat exchanger. However, since the remote control is not operated when the unit is not in operation and the on-off valve of the fan coil unit is not opened as it is, in the present invention, a second terminal control line that performs one-way communication from the heat source control unit to the terminal control unit is newly provided. As a result, during the antifreeze operation, a valve control signal is sent from the heat source control unit to the terminal control unit via the second terminal control line, and the on-off valve is driven to an open state by the first on-off control means. As a result, the circulating fluid that has been heated by the heat source in the heating heat exchanger and warmed as described above can be circulated through the circulating fluid piping.

During freeze prevention operation as described above, it is possible that due to some reason, such as a malfunction inside the outdoor unit, the circulating fluid will not be heated as described above and will instead be circulated through the circulating fluid piping by the circulation pump. In this case, the circulating fluid will continue to flow at a low temperature through the fan coil unit, and condensation may form inside the on-off valve, causing the on-off valve to malfunction. If the on-off valve malfunctions, it may be necessary to disassemble the various parts and appliances within the fan coil unit, or a current leak may occur, causing problems with the electrical equipment (for example, the breaker may trip).

Therefore, according to the present invention, the terminal control unit is provided with a first determination means and a second opening/closing control means. The first determination means determines whether or not a predetermined first temperature condition is satisfied after the opening/closing valve is opened by control of the first opening/closing control means based on the valve control signal as described above during execution of the freeze prevention operation. An example of the first temperature condition may be, for example, that when a predetermined time (first predetermined time) has elapsed after the opening/closing valve is opened, the circulating fluid temperature detected by a sensor provided in the fan coil unit is equal to or higher than a predetermined threshold value (first threshold value).

If the first temperature condition is not satisfied as a result of the judgment by the first judgment means, it is considered that the circulating fluid is not being heated satisfactorily due to some reason such as a malfunction in the outdoor unit, and the second opening/closing control means performs forced control of the opening/closing valve. This forced control is performed to control the opening/closing valve instead of the control by the first opening/closing control means based on the valve control signal as described above. That is, regardless of whether the valve control signal to the first opening/closing control means is a signal to open the opening/closing valve or a signal to close the opening/closing valve, the second opening/closing control means can forcibly open or close the opening/closing valve. By forcibly closing the opening/closing valve by such forced control , it is possible to prevent the circulating fluid at a low temperature from being supplied to the fan coil unit. As a result, it is possible to prevent the opening/closing valve from failing to operate due to the internal condensation.

According to claim 2, the first determination means determines, as the first temperature condition, whether or not a first predetermined time has elapsed after the opening/closing valve is opened by the first opening/closing control means based on the valve control signal, and whether or not the circulating fluid temperature detected by the sensor is equal to or higher than a first threshold value. This makes it possible to reliably identify whether the circulating fluid remains unheated due to some reason on the outdoor unit side during the freeze prevention operation.

According to claim 3, even after the first temperature condition is not satisfied and the second opening/closing control means closes the opening/closing valve by the forced control as described above, the second determination means determines whether or not the predetermined second temperature condition is satisfied. As a result, even if the first temperature condition is not satisfied during the freeze prevention operation because the outdoor unit does not initially heat the circulating fluid due to reasons such as the outside air temperature being too low, if the outdoor unit subsequently begins to heat the circulating fluid sufficiently, it can be clearly identified that the second temperature condition is satisfied.

According to claim 4, the second determination means determines, as the second temperature condition, whether or not the circulating fluid temperature detected by the sensor is equal to or higher than the second threshold value when a second predetermined time has elapsed after the second opening/closing control means has closed the opening / closing valve by the forced control , the opening/closing valve is opened again, and a third predetermined time has elapsed. This makes it possible to reliably identify whether the outdoor unit is not initially heating the circulating fluid during the freeze prevention operation, but that the outdoor unit is then beginning to sufficiently heat the circulating fluid as time passes.

According to claim 5, when the second determination means determines that the second temperature condition is satisfied, it is deemed that the circulating fluid has been sufficiently heated over time as described above. That is, the second opening/closing control means continues the forced control , but when a valve control signal is input from the heat source control unit via the second terminal control line or a valve control signal is transmitted from the remote control corresponding to the end of the freeze prevention operation, the second opening/closing control means terminates the forced control . As a result, when the freeze prevention operation on the outdoor unit side is terminated or the user appropriately operates the remote control, the forced control is terminated and normal opening/closing control of the opening/closing valve by the first opening/closing control means is resumed, and the opening/closing valve can be opened.

According to the invention of claim 6, when the second determination means determines that the second temperature condition is not satisfied, the circulating fluid has not been sufficiently heated over time as described above, and it is therefore deemed that some abnormality, such as a breakdown, has occurred in the outdoor unit. This allows the second opening/closing control means to continue the forced control and keep the opening/closing valve in a closed state. However, only when a valve control signal is transmitted from the remote control, the second opening/closing control means ends the forced control . This allows the user to end the forced control and return to normal opening/closing control of the opening/closing valve by the first opening/closing control means, opening the opening/closing valve, by appropriately operating the remote control, knowing that there is some abnormality in the outdoor unit.

FIG. 1 is a circuit diagram of an entire hot water heating system to which the hot water heating system of one embodiment of the present invention is applied. A diagram explaining the operation of a heat pump during heating only operation Diagram explaining operation during gas-only heating operation Diagram explaining operation during heat pump/gas heating operation Functional diagram of a heat pump control device Functional configuration diagram of heat exchange unit control device Functional diagram of boiler control device A diagram explaining the operation during anti-freeze operation (part 1) A diagram explaining the operation during anti-freeze operation (part 2) FIG. 1 is a flowchart showing a control procedure for anti-freeze operation executed by a heat pump control device. A circuit diagram showing the main configuration related to the transmission and reception of operation information between a terminal control unit and a heat pump control device. A flowchart showing the control procedure of the forced control executed by the terminal control unit.

One embodiment of the present invention will be described below with reference to Figures 1 to 12.

This embodiment is an embodiment in which the present invention is applied to a combined heat source hot water heating system.

<Overall circuit configuration>
The overall circuit configuration of the hot water heating system 1 of this embodiment is shown in Fig. 1. As shown in Fig. 1, the hot water heating system 1 includes a heat exchange unit 4A and a gas heating water heater unit 4B, which are respectively installed indoors of a building, and a heat pump unit 5, which is installed outdoors of the building as an outdoor unit. The hot water heating system 1 includes a terminal circulation circuit 30 as a liquid circulation circuit that circulates a circulating liquid L (e.g., water or antifreeze liquid) to a fan coil unit 36 as an indoor unit, a hot water circulation circuit 40 that is provided in the heat exchange unit 4A and the gas heating water heater unit 4B and can heat the circulating liquid L on the fan coil unit 36 side by using a heat source by gas heating, and a refrigerant circulation circuit 50 that is provided in the heat pump unit 5 and can heat or cool the circulating liquid L on the fan coil unit 36 side by using an air heat source. As such, the hot water heating system 1 of this embodiment has the fan coil unit 36 as an indoor unit and the heat pump unit 5 as an outdoor unit, and constitutes a hot water heating system that heats the space to be air-conditioned by heat exchange between the indoor air and the circulating liquid L.

<Hot water circulation circuit>
The hot water circulation circuit 40 includes a variable output gas heater (so-called burner) 43 , a first heat exchanger 41 , a heating heat exchanger 45 , and a hot water circulation pump 44 , which are connected in a circular manner by hot water piping 42 .

The first heat exchanger 41 is, for example, a plate-type heat exchanger. This plate-type heat exchanger is made up of a plurality of heat transfer plates stacked together, with refrigerant passages 41a through which hot water C1 (e.g., water or antifreeze; see Figures 3 and 4, etc., described below) and circulating liquid passages 41b through which the circulating liquid L flows alternately formed on either side of each heat transfer plate.

The heating heat exchanger 45 receives heat from the gas heater 43 to heat the hot water in the hot water pipe 42. At this time, a hot water heat exchanger 46 is provided so as to be able to receive heat from the gas heater 43, just like the heating heat exchanger 45. City water is supplied from the outside to the water pipe 47 provided in the hot water heat exchanger 46, and the hot water heated by the heat received from the gas heater 43 is supplied to a hot water tap 48 connected to the water pipe 47. In other words, the gas heater 43, the heating heat exchanger 45, and the hot water heat exchanger 46 constitute a so-called boiler.

The temperature of the hot water C1 discharged from the gas heater 43 is detected by the boiler feed temperature sensor 42a, and the detection result is input to the boiler control device 63. A main remote control 60 is also connected to the boiler control device 63, and the heating capacity of the gas heater 43 can be adjusted by manually operating the main remote control 60.

<Refrigerant Circulation Circuit>
The refrigerant circulation circuit 50 includes a variable capacity compressor 53, a second heat exchanger 51 serving as a heating heat exchanger, an expansion valve 54, and an air heat exchanger 55 configured to be able to exchange heat with outside air, which are connected in a ring shape by refrigerant piping 52. The refrigerant piping 52 is provided with a four-way valve 58 serving as a switching valve for switching the flow direction of the refrigerant C2 (see Figures 2 and 4, which will be described later) in the refrigerant circulation circuit 50. The air heat exchanger 55 is also provided with a blower fan 56.

The second heat exchanger 51 is, as described above, for example a plate-type heat exchanger, in which refrigerant passages 51a through which the refrigerant C2 flows and circulating liquid passages 51b through which the circulating liquid L flows are alternately formed on either side of each heat transfer plate.

The temperature of the refrigerant C2 discharged from the compressor 53 is detected by the refrigerant discharge temperature sensor 52a. Similarly, the temperature of the refrigerant C2 on the low pressure side (when heating) or high pressure side (when cooling) is detected by the refrigerant temperature sensor 52b installed in the refrigerant piping 52 from the expansion valve 54 to the air heat exchanger 55. Furthermore, the temperature of the outside air is detected by, for example, an outside air temperature sensor 57 installed in the air heat exchanger 55 or in its vicinity. The detection results of the refrigerant discharge temperature sensor 52a, the refrigerant temperature sensor 52b, and the outside air temperature sensor 57 are input to a heat pump control device 62 (corresponding to a heat source control unit). In addition, the heat pump control device 62 is connected to a main remote control 60, for example, located on the indoor side, so as to be able to communicate with the heat pump control device 62. The heat pump control device 62 can control the refrigerant circulation circuit 50 based on manual operation of the main remote control 60 to adjust its capacity (details will be described later).

The refrigerant C2 in the refrigerant circulation circuit 50 can be any refrigerant, such as an HFC refrigerant such as R410A or R32, or a carbon dioxide refrigerant.

<Terminal circulation circuit>
In the terminal circulation circuit 30, the first heat exchanger 41, the second heat exchanger 51, and the fan coil unit 36 are connected in a ring shape in this order from the upstream side by a load pipe 31 serving as a circulating fluid pipe. The load pipe 31 is provided with a circulating fluid circulating pump 32 serving as a circulating pump for circulating the circulating fluid L in the terminal circulation circuit 30, and a pressure adjustment tank (not shown) for storing the circulating fluid L and adjusting the pressure of the terminal circulation circuit 30. The second heat exchanger 51, the circulating fluid circulating pump 32, and the pressure adjustment tank are provided in the heat pump unit 5, and the first heat exchanger 41 is provided in the heat exchange unit 4A.

At this time, in the terminal circulation circuit 30, the first heat exchanger 41 and the second heat exchanger 51 are connected in series, and as described above, the second heat exchanger 51 is arranged upstream of the first heat exchanger 41 with respect to the flow of the circulating liquid L circulating in the terminal circulation circuit 30. In other words, the hot water heating system 1 is a combined heat source heat pump device in which the first heat exchanger 41 of the hot water circulation circuit 40, which can heat the circulating liquid L on the fan coil unit 36 side using a heat source by gas heating, and the second heat exchanger 51 of the refrigerant circulation circuit 50, which uses an air heat source to heat or cool the circulating liquid L on the fan coil unit 36 side, are connected in series to the terminal circulation circuit 30.

The load piping 31 is provided with a return temperature sensor 34 for detecting the temperature of the circulating fluid L flowing from the fan coil unit 36 into the second heat exchanger 51, a second forward temperature sensor 35 for detecting the temperature of the circulating fluid L flowing from the second heat exchanger 51 to the first heat exchanger 41 side, and a first forward temperature sensor 33 for detecting the temperature of the circulating fluid L flowing from the first heat exchanger 41 to the fan coil unit 36 side. The detection result of the first forward temperature sensor 33 is input to the heat exchange unit control device 61. The detection results of the return temperature sensor 34 and the second forward temperature sensor 35 are input to the heat pump control device 62.

The heat pump control device 62, the heat exchange unit control device 61, and the boiler control device 63 are connected to each other so that they can transmit and receive information, and can share the detection results of each sensor input as described above with each other.

<Fan coil unit>
The fan coil unit 36 can be operated by a terminal remote control 71. That is, the fan coil unit 36 includes therein a heat exchanger 36a (corresponding to an indoor heat exchanger) that exchanges heat between the indoor air in the space to be air-conditioned and the circulating fluid L, a blower fan 36d for performing the heat exchange in the heat exchanger 36a, a thermal valve V (corresponding to an on-off valve) that opens and closes the load piping 31 in the fan coil unit 36, an indoor temperature sensor (not shown) that detects the indoor temperature, a water temperature sensor 36c (corresponding to a sensor) that detects the temperature of the circulating fluid L flowing through the fan coil unit 36, and the terminal control unit 36b. The terminal control unit 36b receives signals from the indoor temperature sensor and the water temperature sensor 36c in the fan coil unit 36 and a signal from the terminal remote control 71, and controls the driving of the blower fan 36d and the thermal valve V. As a result, the fan coil unit 36 supplies the circulating fluid L heated or cooled in the second heat exchanger 51 or the first heat exchanger 41 to the internal heat exchanger 36a, and drives the blower fan 36d to exchange heat with the indoor air, thereby heating or cooling the room. Although one fan coil unit 36 is provided in Fig. 1, two or more fan coil units 36 may be provided, and the number and specifications are not particularly limited.

The terminal remote control 71 is equipped with a heating switch 74 for causing the fan coil unit 36 to perform hot air heating operation to heat the room, a cooling switch 75 for causing the fan coil unit 36 to perform cold air cooling operation to cool the room, a stop switch 76 for stopping the operation of the fan coil unit 36, an indoor temperature setting switch 77 for setting the indoor temperature, and a display unit 78 for displaying the indoor set temperature and the operating status, and is connected to the terminal control unit 36b so as to be able to communicate with it.

<Warm air heating operation>
The hot water heating system 1 can selectively function as a heating device that performs the hot air heating operation or as a cooling device that performs the cold air cooling operation by switching the four-way valve 58. In particular, in the case of the hot air heating operation, three types of heating operation can be selectively performed: a heating operation in which the circulating liquid L is heated only by using the air heat source via the refrigerant circulation circuit 50 (hereinafter, appropriately, referred to as "HP only heating operation"), a heating operation in which the circulating liquid L is heated only by using the heat source by gas heating via the hot water circulation circuit 40 (hereinafter, appropriately, referred to as "gas only heating operation"), and a heating operation in which the circulating liquid L is heated by both using the air heat source via the refrigerant circulation circuit 50 and using the heat source by gas heating via the hot water circulation circuit 40 (hereinafter, appropriately, referred to as "HP/gas heating operation").

<HP independent heating operation>
FIG. 2 shows the state during HP-only heating operation. In order to prevent the illustration from becoming complicated, various signal lines shown in FIG. 1 are omitted. During HP-only heating operation shown in FIG. 2, in the refrigerant circulation circuit 50, the four-way valve 58 is switched as shown in the figure, so that the refrigerant C2 discharged from the compressor 53 flows through the second heat exchanger 51, the expansion valve 54, and the air heat exchanger 55 in this order, and then a flow path is formed that returns to the compressor 53. As a result, the refrigerant C2 in a gas state sucked at a low temperature and low pressure is compressed by the compressor 53 to become a high-temperature and high-pressure gas, and then exchanges heat with the circulating liquid L flowing through the terminal circulation circuit 30 in the second heat exchanger 51 that functions as a condenser, heating the circulating liquid L and changing it into a high-pressure liquid. The refrigerant C2 that has become liquid in this way is reduced in pressure in the expansion valve 54 (shown as an example at an opening smaller than fully open) to become a low-pressure liquid that is easy to evaporate, and in the air heat exchanger 55, which functions as an evaporator, it exchanges heat with the air sent by the operation of the blower fan 56, evaporates and turns into gas, absorbing heat, and then returns to the compressor 53 as a low-temperature, low-pressure gas.

At this time, in the terminal circulation circuit 30, the circulating liquid L flowing into the second heat exchanger 51 by the circulating liquid circulation pump 32 receives heat in the second heat exchanger 51, which functions as an evaporator, by exchanging heat with the outside air in the air heat exchanger 55 and exchanging heat with the refrigerant C2 heated as described above. The circulating liquid L thus heated is then supplied to the fan coil unit 36, and in the heat exchanger 36a, it exchanges heat with the indoor air sent by the operation of the blower fan 36d. As a result, heating is performed by the warm air of the heated air.

In the above, heating operation has been described as an example, but when a terminal capable of cooling is used as the fan coil unit 36, the four-way valve 58 can be switched to form a flow path that causes the refrigerant C2 discharged from the compressor 53 to flow through the air heat exchanger 55, the expansion valve 54, and the second heat exchanger 51 in that order, and then return it to the compressor 53, thereby performing cooling operation (detailed description omitted).

<Gas only heating operation>
Fig. 3 shows the state during gas-only heating operation. As described above, various signal lines shown in Fig. 1 are omitted. During gas-only heating operation shown in Fig. 3, the hot water C1 flowed into the heating heat exchanger 45 by the hot water circulation pump 44 is heated by the thermal power of the gas heater 43 in the heating heat exchanger 45 and becomes high temperature. Thereafter, the hot water C1, which has been kept at a high temperature, exchanges heat with the circulating liquid L flowing through the terminal circulation circuit 30 in the first heat exchanger 41 to heat the circulating liquid L and lower its temperature, and then returns to the heating heat exchanger 45 again.

At this time, in the terminal circulation circuit 30, the circulating fluid L flowing into the first heat exchanger 41 by the circulating fluid circulation pump 32 receives heat in the first heat exchanger 41 through heat exchange with the hot water C1 heated as described above in the gas heater 43. The circulating fluid L thus heated is then supplied to the fan coil unit 36, and in the heat exchanger 36a, exchanges heat with the indoor air sent by the operation of the blower fan 36d. As a result, heating is performed by the hot air of the heated air.

<HP/Gas heating operation>
Fig. 4 shows the state during HP/gas heating operation. As described above, the various signal lines shown in Fig. 1 are omitted. During HP/gas heating operation shown in Fig. 4, both the heating of the refrigerant C2 by the air heat exchanger 55 in the refrigerant circulation circuit 50 described with reference to Fig. 2 and the heating of the hot water C1 by the gas heater 43 in the hot water circulation circuit 40 described with reference to Fig. 3 are performed.

In the terminal circulation circuit 30, the circulating liquid L flowing into the second heat exchanger 51 by the circulating liquid circulation pump 32 receives heat by exchanging heat with the heated refrigerant C2 in the second heat exchanger 51 as described above, and then flows into the first heat exchanger 41. The circulating liquid L flowing into the first heat exchanger 41 receives further heat by exchanging heat with the heated hot water C1 as described above. The circulating liquid L thus heated by the air heat source and the gas heating heat source is then supplied to the fan coil unit 36, and, as described above, exchanges heat with the indoor air in the heat exchanger 36a to perform heating.

<Functional configuration of the control device>
Next, the heat exchange unit control device 61, the boiler control device 63, and the heat pump control device 62 in this embodiment will be described. Although detailed illustrations are omitted, the heat exchange unit control device 61, the boiler control device 63, and the heat pump control device 62 each include a storage unit for storing various data and programs, and a control unit for performing calculation and control processing. The functional configurations of the heat exchange unit control device 61, the boiler control device 63, and the heat pump control device 62 will be described with reference to Figures 5, 6, and 7. Note that in the following Figures 5, 6, and 7, the signal transmission and reception between the heat exchange unit control device 61, the boiler control device 63, and the heat pump control device 62, which can transmit and receive signals to and from each other as described above, and the signal transmission and reception via each control device are omitted as appropriate, and the signals that are substantially input and output to each control unit described below are shown.

<Heat pump control device>
As shown in FIG. 5, the heat pump control device 62 functionally comprises the compressor control unit 62A, the expansion valve control unit 62B, the pump control unit 62C, the fan control unit 62D, the four-way valve control unit 62E, and the fan coil control unit 62F.

The compressor control unit 62A controls the rotation speed of the compressor 53, for example, in response to the temperature of the circulating fluid L detected by the return temperature sensor 34 and the second forward temperature sensor 35. In this particular example, the compressor control unit 62A controls the rotation speed of the compressor 53 so that the temperature of the circulating fluid L detected by the second forward temperature sensor 35 becomes a desired target temperature corresponding to, for example, the operation of the main remote control 60.

The expansion valve control unit 62B controls the valve opening degree of the expansion valve 54 according to the temperature of the refrigerant C2 detected by the refrigerant discharge temperature sensor 52a. In this example in particular, the expansion valve control unit 62B controls the valve opening degree of the expansion valve 54 so that the temperature of the refrigerant C2 detected by the refrigerant discharge temperature sensor 52a becomes a control target temperature corresponding to, for example, the operation of the main remote control 60.

The pump control unit 62C controls the rotation speed of the circulating fluid circulation pump 32, for example, depending on the desired target temperature of the circulating fluid L and the type of operation.

The fan control unit 62D controls the rotation speed of the blower fan 56 according to the outside air temperature detected by the outside air temperature sensor 57.

The four-way valve control unit 62E receives an operation instruction from the main remote control 60 (a control signal instructing the start and stop of either heating operation or cold air operation) and an operation ON/OFF signal from the heat exchange unit control device 61. The four-way valve control unit 62E determines in what operating mode the refrigerant circulation circuit 50 will actually be operated in response to the operation instruction, and outputs corresponding operating information to the compressor control unit 62A, the expansion valve control unit 62B, the pump control unit 62C, the fan control unit 62D, and the heat exchange unit control device 61. The four-way valve control unit 62E also outputs a control signal corresponding to the determined operating mode to the four-way valve 58, switching the four-way valve 58.

Operation information (presence or absence of a hot water request signal or a cold water request signal) of the fan coil unit 36 transmitted from the terminal control unit 36b of the fan coil unit 36 by one-way communication (details will be described later) is input to the fan coil control unit 62F. In addition, the outside air temperature detected by the outside air temperature sensor 57 is also input to the fan coil control unit 62F.

The fan coil control unit 62F outputs a freeze prevention operation instruction to perform freeze prevention operation (details will be described later) to the compressor control unit 62A, the expansion valve control unit 62B, the pump control unit 62C, the fan control unit 62D, the four-way valve control unit 62E, and the heat exchange unit control device 61 according to the operation information of the fan coil unit 36 and the outside air temperature, and transmits a valve control signal (ON signal) of the thermal valve V to the terminal control unit 36b of the fan coil unit 36 by one-way communication (details will be described later).

<Heat exchange unit control device>
As shown in FIG. 6, the heat exchange unit control device 61 functionally comprises an operation control section 61A, a heating control section 61B, and a pump control section 61C.

The operation control unit 61A judges whether to operate the gas heater 43 of the hot water circulation circuit 40, for example, based on the temperature of the outside air detected by the outside air temperature sensor 57, the temperature of the circulation liquid L from the first heat exchanger 41 detected by the first forward temperature sensor 33, and the above-mentioned operation information input from the heat pump control device 62, and more specifically, whether to operate the gas heater 43 of the hot water circulation circuit 40 together with the compressor 53 of the refrigerant circulation circuit 50 (=HP gas heating operation), or whether to operate the gas heater 43 of the hot water circulation circuit 40 (=gas only heating operation) (with the compressor 53 of the refrigerant circulation circuit 50 not operating). Then, based on the judgment result, it outputs an operation ON signal corresponding to the case of operation or an operation OFF signal corresponding to the case of not operating to the heat pump control device 62 and the boiler control device 63.

The heating control unit 61B outputs a heating control signal to the boiler control device 63 to control the magnitude of the output of the gas heater 43 based on the temperature of the circulating liquid L from the first heat exchanger 41 detected by the first temperature sensor 33.

The pump control unit 61C outputs a rotation control signal to the boiler control device 63 to control the rotation speed of the hot water circulation pump 44, for example, depending on the desired target temperature of the circulating liquid L and the type of operation.

<Boiler control device>
As shown in Figure 7, the boiler control device 63 controls the rotation speed of the hot water circulation pump 44 and the output of the gas heater 43 based on, for example, a heating control signal from the heating control unit 61B, a rotation control signal from the pump control unit 61C, and the delivery temperature of the hot water C1 detected by the boiler delivery temperature sensor 42a.

<The necessity of anti-freeze operation>
In the hot water heating system 1 having the above basic configuration and operation, a part of the load piping 31 may be arranged outdoors. For example, in the example shown in FIG. 1, the part of the load piping 31 near the heat pump unit 5 is arranged outdoors. Therefore, when such a hot water heating system 1 is used, for example, in a very cold area, it is necessary to prevent the circulating liquid L from freezing when not in operation in winter. In particular, when the fan coil unit 36 that exchanges heat with indoor air is used, a part of the load piping 31 near the fan coil unit 36 (parts 31X, 31Y between the heat exchangers 41, 51 and the heat exchanger 36a in the example shown in FIG. 1) may be arranged outdoors from the viewpoint of indoor aesthetics, etc. In this case, it is also necessary to take into consideration the prevention of freezing in this outdoor part.

<Anti-freezing operation (part 1)>
As a freeze prevention measure, normally, the circulating fluid circulating pump 32 is started as shown in Fig. 8 as "freeze prevention operation (1)" before the circulating fluid L falls below the freezing temperature, to circulate the circulating fluid L. By starting the circulating fluid circulating pump 32, the circulating fluid L circulates in the load piping 31 in the following order: second heat exchanger 51 → first heat exchanger 41 → fan coil unit 36 → circulating fluid circulating pump 32 → second heat exchanger 51 → .... This flow of the circulating fluid L in the load piping 31 provides primary freeze prevention.

<Anti-freezing operation (part 2)>
For example, when the outside air temperature further drops and it is possible that freezing prevention is difficult only by the circulation of the circulating liquid L in the above-mentioned freezing prevention operation (part 1), the compressor 53 is started, and the refrigerant C2 that has exchanged heat with the outside air is radiated to the circulating liquid L, as shown in "freezing prevention operation (2)" in Fig. 9. That is, similar to the HP-only heating operation shown in Fig. 2 described above, in the refrigerant circulation circuit 50, the refrigerant C2 compressed by the compressor 53 radiates heat to the circulating liquid L in the second heat exchanger 51, is decompressed in the expansion valve 54, absorbs heat in the air heat exchanger 55, and then returns to the compressor 53. In this case, unlike the HP-only heating operation in Fig. 2, the amount of heat radiation is not as much as that required for warm air heating by the fan coil unit 36 (enough to prevent freezing), so that, for example, the opening degree of the expansion valve 54 is larger than that in Fig. 2 (as an example, fully open). The circulating liquid L is heated by receiving heat from the refrigerant C2 in the second heat exchanger 51, and then circulates in the same manner as described above from the first heat exchanger 41 → the fan coil unit 36 → the circulating liquid circulating pump 32 → the second heat exchanger 51 → .... In this manner, secondary freezing prevention is achieved by heating the circulating liquid L in the load piping 31.

<Control procedure for anti-freeze operation>
Next, the control procedure of the freeze prevention operation, including the transition from the freeze prevention operation (part 1) to the freeze prevention operation (part 2), will be described with reference to Fig. 10. Note that Fig. 10 shows the control procedure executed by the heat exchange unit control device 61, the heat pump control device 62, and the boiler control device 63 in cooperation with each other in the hot water heating system 1 of this embodiment.

In FIG. 10, first in S5, it is determined whether the outside air temperature detected by the outside air temperature sensor 57 is below a predetermined temperature (-10°C in this example). If the outside air temperature falls to a value lower than -10°C, the result is Yes, and the process moves to S15.

In S15, a valve control signal (ON signal) to open the thermal valve V is sent from the heat pump control device 62 to the terminal control unit 36b of the fan coil unit 36. This causes the thermal valve V of the fan coil unit 36 to open. The valve control signal at this time is sent and received via the second terminal control line 145 of the two control lines (E-con communication lines) that connect the terminal control unit 36b and the heat pump control device 62 by wire, that is, the first terminal control line 144 and the second terminal control line 145. Details related to the sending and receiving of signals via the first terminal control line 144 and the second terminal control line 145 will be explained below with reference to FIG. 11.

<First terminal control line>
First, the main configuration related to signal transmission and reception via the first terminal control line 144 will be described with reference to FIG. 11. In FIG. 11, the terminal control unit 36b includes a microcomputer 130 and a signal transmission circuit 131. The microcomputer 130 includes an output port OUT1, and the signal transmission circuit 131 includes a contact 132. When the heating switch 74 of the terminal remote control 71 is operated by a user to instruct the start of operation, the terminal control unit 36b receives the instruction signal. Then, in response to the received instruction signal, the terminal control unit 36b opens the thermal valve V and drives the blower fan 36d, and outputs a signal from the output port OUT1 of the microcomputer 130 to close the contact 132 of the signal transmission circuit 131. As a result, a hot water request signal is output to the heat pump control device 62.

Specifically, the heat pump control device 62 includes a microcomputer 141 and a signal receiving circuit 142. The microcomputer 141 includes an input port IN1. As described above, a first terminal control line 144 (E-con communication line) that transmits a signal from the terminal control unit 36b in one direction to the heat pump control device 62 is provided between the heat pump control device 62 and the terminal control unit 36b. In this example, the first terminal control line 144 is composed of two cores, a first core 144A and a second core 144B. The E-con communication is a common specification among major gas companies, heating equipment manufacturers, etc., and refers to communication that starts and stops the operation of the heat source device by a one-way signal output from a terminal device. In other words, the E-con communication line can be used inexpensively and is highly versatile.

The flow of operations in the above configuration up to the output of the hot water request signal from the terminal control unit 36b to the heat pump control device 62 is described below. Here, it is assumed that a predetermined power switch provided on the main remote control 60 is turned on and the heat pump unit 5 is in a standby state.

When the terminal control unit 36b receives a corresponding heating start instruction signal from the terminal remote control 71 based on the user's operation of the heating switch 74, the microcomputer 130 outputs a signal from the output port OUT1 and closes the contact 132 of the signal transmission circuit 131. When the contact 132 is closed, the voltage signal Vcc of the heat pump control device 62 is output to the signal transmission circuit 131 via the first core wire 144A of the first terminal control line 144, and is further applied to the signal receiving circuit 142 via the second core wire 144B of the first terminal control line 144. As a result, the voltage level of the input port IN1 of the microcomputer 141 changes from HIGH to LOW, and the microcomputer 141 detects that a hot water request signal for heating the fan coil unit 36 has been output (i.e., the hot water request signal is being received).

When a corresponding heating stop instruction signal is subsequently received from the terminal remote control 71 based on the user's operation of the stop switch 76 of the terminal remote control 71, the microcomputer 130 closes the thermal valve V, stops the blower fan 36d, and outputs a signal from the output port OUT1 to open the contact 132 of the signal transmission circuit 131. When the contact 132 is opened, the voltage level of the input port IN1 of the microcomputer 141 of the heat pump control device 62 changes from LOW to HIGH. As a result, the microcomputer 141 detects that the output of the hot water request signal has stopped (i.e., the hot water request signal is no longer being received).

In addition, the cooling switch 75 of the terminal remote control 71 is operated to cause the fan coil unit 36 to perform cooling operation, and a cold water request signal is output from the terminal control unit 36b to the heat pump control device 62 in the same manner as described above by a separately provided E-con communication circuit (not shown), and detailed explanation will be omitted.

<Second terminal control line>
On the other hand, as described above, the transmission and reception of the valve control signal in S15 is performed by the second terminal control line 145 that transmits a signal from the heat pump control device 62 in one direction to the terminal control unit 36b. This second terminal control line 145 is composed of two wires, a first core wire 145A similar to the first core wire 144A and a second core wire 145B similar to the second core wire 144B, and has a similar configuration to the configuration related to the transmission and reception of the hot water request signal and the cold water request signal described above (the configuration in which the microcomputers 130 and 141 are connected via the first terminal control line 144 in FIG. 11), with the transmitting side and the receiving side reversed. Therefore, in FIG. 11, only the second terminal control line 145 is simply illustrated, and the signal receiving circuit and the signal transmitting circuit connected to the second terminal control line 145 are not illustrated.

In S15, a valve control signal (ON signal) for opening the thermal valve V is transmitted from the fan coil control unit 62F of the heat pump control device 62 to the terminal control unit 36b of the fan coil unit 36 via the second terminal control line 145. In addition, the fan coil control unit 62F outputs the above-mentioned freeze prevention operation instruction to the other control units 62A to 62E.

In this way, the terminal control unit 36b has the function of driving the thermal valve V to open and close (function as a first opening and closing control means) by an operation/stop signal from the terminal remote control 71 and a valve control signal from the heat pump control device 62 via the second terminal control line 145.

Then, in S20, the pump control unit 62C of the heat pump control device 62 starts driving the circulating fluid circulating pump 32. This executes the freeze prevention operation (part 1) described above with reference to FIG. 8. Then, the process proceeds to S25.

In S25, it is determined whether the temperature detected by the second forward temperature sensor 35, i.e., the forward temperature of the circulating liquid L flowing from the second heat exchanger 51 to the first heat exchanger 41 side, is less than a predetermined temperature (12°C in this example). This predetermined temperature is a temperature at which the freezing does not occur in the load pipe 31 and condensation does not easily occur in the fan coil unit 36 when transitioning from the freeze prevention operation (1) to the freeze prevention operation (2) as described above occurs at the predetermined temperature. In other words, this predetermined temperature is a temperature at which it is known that the freezing does not occur in the load pipe 31 and condensation does not easily occur in the fan coil unit 36 when transitioning from the freeze prevention operation (1) to the freeze prevention operation (2) occurs with the forward temperature at least equal to or higher than the predetermined temperature, based on an appropriate experiment performed in advance or an analysis/simulation using an appropriate method.

The forward temperature of the circulating fluid L at this time is an example of the temperature of the circulating fluid. Note that, instead of the forward temperature of the circulating fluid L from the second heat exchanger 51 detected by the second forward temperature sensor 35, the forward temperature of the circulating fluid L from the first heat exchanger 41 detected by the first forward temperature sensor 33 may be used. Furthermore, instead of the forward temperature of the circulating fluid L, the return temperature of the circulating fluid L to the second heat exchanger 51 detected by the return temperature sensor 34 may be used.

As long as the temperature of the circulating fluid L is 12°C or higher, S25 is judged as No and S15 and S20 are continued. If the temperature of the circulating fluid L falls below 12°C, for example due to a drop in temperature, S25 is judged as Yes and the process moves to S30.

In S30, the compressor control unit 62A of the heat pump control device 62 starts driving the compressor 53, and the control units 62B to 62E shown in FIG. 5 control the corresponding parts of the heat pump unit 5. Hereinafter, this state will be referred to simply as "heat pump unit startup" as appropriate (as in the drawings). This causes a transition from anti-freeze operation (part 1) in FIG. 8 to anti-freeze operation (part 2) in FIG. 9. The heat pump control device 62 that executes S15, S20, and S30 corresponds to anti-freeze control means. Then, the process transitions to S35.

In S35, it is determined whether the temperature detected by the second forward temperature sensor 35, i.e., the forward temperature of the circulating fluid L flowing from the second heat exchanger 51 to the first heat exchanger 41, exceeds a predetermined temperature (25°C in this example). As described above, the forward temperature of the circulating fluid L from the first heat exchanger 41 detected by the first forward temperature sensor 33 may be used as the determination target, or the return temperature of the circulating fluid L to the second heat exchanger 51 detected by the return temperature sensor 34 may be used.

While the delivery temperature of the circulating fluid L is below 25°C, S35 is judged as No and S30 continues to be performed, and when the delivery temperature of the circulating fluid L exceeds 25°C due to heat received from the heat pump unit 5 started in S30, S35 is judged as Yes and the process moves to S40.

In S40, the compressor control unit 62A of the heat pump control device 62 stops the compressor 53 and other components that were started in S30. Hereinafter, this state will be referred to simply as "heat pump unit stopped" as appropriate (as in the drawings).

Then, in S42, as in S5, it is determined whether the outside air temperature detected by the outside air temperature sensor 57 is below the predetermined temperature (-10°C in this example). If the outside air temperature remains below -10°C, the result is Yes, and the process returns to S15 and the same procedure as above is repeated. If the temperature is -10°C or higher, the result is No, and the process moves to S45.

In S45, the circulating fluid circulating pump 32, which was started in S20, is stopped by the pump control unit 62C of the heat pump control device 62. In addition, a valve control signal (OFF signal) for closing the thermal valve V is sent from the fan coil control unit 62F to the terminal control unit 36b of the fan coil unit 36 via the second terminal control line 145, and the thermal valve V, which was opened in S15, is closed. After S45, this flow ends.

<Condensation inside the thermal valve during freeze prevention operation>
Here, during the freeze prevention operation as described above, due to some reason such as a failure occurring inside the heat pump unit 5, the circulating liquid L may circulate through the load pipe 31 by the circulating liquid circulation pump 32 without being heated. That is, in the freeze prevention operation flow of FIG. 10, even if the freeze prevention operation (part 2) of S30 is performed, due to a failure occurring inside the heat pump unit 5, the temperature of the circulating liquid L does not rise and the temperature condition of S35 cannot be satisfied. In this case, the circulating liquid L at a low temperature continues to flow through the fan coil unit 36, and the thermal valve V may break down due to condensation inside the thermal valve V. If the thermal valve V breaks down, it may be necessary to disassemble each part or device in the fan coil unit 36, or electrical equipment may be impaired due to an electric leakage (for example, a breaker may trip, etc.).

<Features of the embodiment: forced control >
In order to avoid the above-mentioned condensation, in this embodiment, after the thermal valve V is opened based on the valve control signal (ON signal) from the heat pump control device 62 as described above during the freeze prevention operation, it is determined whether or not a predetermined first temperature condition (described in detail later) is satisfied. If the first temperature condition is not satisfied, it is determined that the circulating fluid L is not being sufficiently heated due to some reason such as a malfunction in the heat pump unit 5, and a forced control is performed to forcibly close the thermal valve V. This prevents the circulating fluid L at a low temperature from being supplied into the fan coil unit 36, thereby preventing malfunction of the thermal valve V due to internal condensation.

<Control procedure for forced control >
FIG. 12 shows a control procedure executed by the terminal control unit 36b to perform the above-mentioned forced control .

In FIG. 12, first, in S105, it is determined whether the fan coil unit 36 is out of operation and whether a valve control signal (the ON signal) to the thermal valve V has been received from the heat pump control device 62 via the second terminal control line 145. In other words, it is determined whether the freeze prevention operation has started. If the valve control signal (ON signal) to the thermal valve V in the fan coil unit 36 that is out of operation is received, a Yes determination is made and the process moves to S115, where the thermal valve V is opened by the terminal control unit 36b.

Next, in S116, it is determined whether a valve control signal (OFF signal) to the thermal valve V has been received by operating the terminal remote control 71, or whether the valve control signal (OFF signal) to the thermal valve V has been received from the heat pump control device 62 via the second terminal control line 145 in conjunction with the end of the freeze prevention operation. In other words, it is determined whether a command to close the thermal valve V has been issued on the fan coil unit 36 side, or whether the freeze prevention operation has ended.

If neither of the above two has been received, the result is No and the process proceeds to S120, where it is determined whether or not a first predetermined time (20 minutes in this example; similarly below) has elapsed since the thermal valve V was opened in S115. Until 20 minutes have elapsed, the result is No, and the process returns to S116 and the same procedure is repeated. If, during this repetition of S116 → S117 → S116 →..., a valve control signal (OFF signal) to the thermal valve V by operation of the terminal remote control 71, or a valve control signal (OFF signal) to the thermal valve V from the heat pump control device 62 accompanying the end of freeze prevention operation is received, S117 is determined as Yes and this flow ends.

On the other hand, if 20 minutes have elapsed while the above steps S116 → S117 → S116 → ... are being repeated, S117 will be judged as Yes and the process will move to S120.

In S120, it is determined whether the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than a first threshold value (-20°C in this example; the same applies below). The terminal control unit 36b that executes S120 corresponds to the first determination means. The temperature condition determined in S120, that is, the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than the first threshold value when the first predetermined time has elapsed after the thermal valve V is opened based on the valve control signal (ON signal), corresponds to the first temperature condition.

If the temperature of the circulating fluid L is equal to or higher than the first threshold value, a Yes determination is made and this flow ends. The reason for this is that if the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than the first threshold value, it can be recognized that the circulating fluid L is being heated on the heat pump unit 5 side by the freeze prevention operation.

On the other hand, in S120, if the temperature of the circulating fluid L detected by the water temperature sensor 36c is not equal to or higher than the first threshold value (in this example, if it is lower than −20° C.), a No determination is made, and the process proceeds to S130, where forced control is started to forcibly change the thermal valve V from an open state to a closed state. That is, if the temperature condition of S120 is not satisfied, the thermal valve V is closed in priority to the control of the thermal valve V to be opened based on the valve control signal (ON signal) to the thermal valve V in S105 and S115. This is because, if the temperature of the circulating fluid L detected by the water temperature sensor 36c is not equal to or higher than the first threshold value, it can be recognized that the circulating fluid L remains unheated for some reason on the heat pump unit 5 side during the freeze prevention operation.

Furthermore, in S130, as soon as the forced control is started, a notification lamp 36e (see FIG. 1, etc.) provided on the fan coil unit 36 is turned on to inform the user that the forced control has been performed. The notification lamp 36e is turned on on the outer surface of the fan coil unit 36, the terminal remote control 71, etc. By forcibly closing the thermal valve V by such forced control , it is possible to prevent the circulating fluid L, which remains at a low temperature, from being supplied into the fan coil unit 36, as described above.

Then, in S131, as in S116, it is determined whether a valve control signal (OFF signal) to the thermal valve V has been received by operating the terminal remote control 71, or whether the valve control signal (OFF signal) to the thermal valve V has been received from the heat pump control device 62 via the second terminal control line 145 in conjunction with the end of the freeze prevention operation. If neither of the above two has been received, the result is No and the process moves to S132, where it is determined whether a second predetermined time (60 minutes in this example; the same applies below) has elapsed since the thermal valve V was closed in S130. Until 60 minutes have elapsed, the result is No, and the process returns to S131 and the same procedure is repeated. During this repetition of S131 → S132 → S131 →..., if a valve control signal (OFF signal) to the thermal valve V is received by operating the terminal remote control 71, or a valve control signal (OFF signal) to the thermal valve V from the heat pump control device 62 accompanying the end of freeze prevention operation is received, S131 is judged as Yes and this flow ends.

On the other hand, if 60 minutes have elapsed while S131 → S132 → S131 → ... are being repeated, S132 is judged as Yes and the process proceeds to S133. In S133, the thermal valve V, which was closed in S130, is forcibly opened. This allows the circulating liquid L to be supplied to the fan coil unit 36 again.

Then, in S134, as in S116 and S131, it is determined whether a valve control signal (OFF signal) to the thermal valve V by operation of the terminal remote control 71 has been received, or whether the valve control signal (OFF signal) to the thermal valve V has been received from the heat pump control device 62 via the second terminal control line 145 in conjunction with the end of the freeze prevention operation. If neither of the above two has been received, the result is No and the process moves to S135, where it is determined whether a third predetermined time (5 minutes in this example; the same applies below) has elapsed since the thermal valve V was opened in S133. Until 5 minutes have elapsed, the result is No, and the process returns to S134 and the same procedure is repeated. During this repetition of S134 → S135 → S134 →..., if a valve control signal (OFF signal) to the thermal valve V is received by operating the terminal remote control 71, or a valve control signal (OFF signal) to the thermal valve V from the heat pump control device 62 accompanying the end of freeze prevention operation is received, S134 is judged as Yes and this flow ends.

On the other hand, if five minutes have elapsed while the above steps S134 → S135 → S134 → ... are being repeated, S135 will be judged as Yes and the process will move to S136.

In S136, it is determined whether the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than the second threshold value (-20°C in this example). The terminal control unit 36b that executes S136 corresponds to the second determination means. The temperature condition determined in S136, that is, when the first temperature condition is not satisfied and the thermal valve V is closed in S130, the second predetermined time has elapsed in S133 and the thermal valve V is opened, and then the third predetermined time has elapsed in S135, the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than the second threshold value, corresponds to the second temperature condition.

If the temperature of the circulating fluid L is equal to or higher than the second threshold value, S136 is judged as Yes, and in S155, the thermal valve V is closed again.

Thereafter, in S160, it is determined whether or not a valve control signal (OFF signal) to the thermal valve V by operation of the terminal remote control 71, or the valve control signal (OFF signal) to the thermal valve V from the heat pump control device 62 via the second terminal control line 145 in conjunction with the end of the freeze prevention operation, has been received. If either of these has been received, S160 is determined as Yes and the process proceeds to S165, where the forced control of the thermal valve V started in S130 is ended and the notification lamp 36e that was turned on in S130 is turned off.

The reason for the above-mentioned control from S155 onwards is that even if the first temperature condition is not met because the heat pump unit 5 does not heat the circulating fluid L initially due to reasons such as the outside air temperature being too low during the freeze prevention operation, if the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than the second threshold value, it can be recognized that the heat pump unit 5 has subsequently sufficiently heated the circulating fluid L. When S165 is completed, this flow ends.

On the other hand, in S136, if the temperature of the circulating fluid L detected by the water temperature sensor 36c is less than the second threshold value (in this example, less than -20°C), the process proceeds to S140. In S140, the thermal valve V is closed again, the notification lamp 36e is turned off, and instead the error lamp 36f is turned on. Note that instead of turning on the error lamp 36f and the notification lamp 36e in the fan coil unit 36, similar lamps may be turned on or equivalent content may be displayed in the terminal remote control 71.

Thereafter, in S145, it is determined whether or not a valve control signal (OFF signal) to the thermal valve V has been received by operating the terminal remote control 71. If the signal has been received, the determination is Yes and the process proceeds to S150, where the forced control of the thermal valve V started in S130 is ended and the error lamp 36f that was turned on in S140 is turned off.

The reason for the above-mentioned control from S140 onwards is that if the second threshold value is not reached in S136, the circulating liquid L has not been sufficiently heated over time as described above, and it is assumed that some abnormality, such as a breakdown, has occurred in the heat pump unit 5. When S150 is completed, this flow ends.

The terminal control unit 36b, which executes steps S130 to S145, S155, and S160 among the steps described above, corresponds to the second opening/closing control means.

Effects of the embodiment
As described above, in the hot water heating system 1 of this embodiment, a predetermined freeze prevention operation is performed in the heat pump unit 5 to prevent the circulating liquid L from freezing when the system is not in operation in winter (see Figs. 8 to 10). To this end, the circulating liquid circulating pump 32 and the compressor 53 provided in the refrigerant circulation circuit 50 are started under the control of the heat pump control device 62, and heat is released from the refrigerant C2 to the circulating liquid L in the second heat exchanger 51. However, since the terminal remote control 71 is not operated when the system is not in operation and the thermal valve V of the fan coil unit 36 is not opened as it is, in this embodiment, a second terminal control line 145 is newly provided for executing one-way communication from the heat pump control device 62 to the terminal control unit 36b.

During the freeze prevention operation, the heat pump control device 62 sends a valve control signal (ON signal) to the terminal control unit 36b via the second terminal control line 145, which causes the terminal control unit 36b to drive the thermal valve V to an open state. As a result, the circulating liquid L, which has been heated by receiving heat from the refrigerant in the second heat exchanger 51 as described above, can be circulated within the load piping 31.

During the freeze prevention operation as described above, due to some reason, such as a malfunction inside the heat pump unit 5, the circulating fluid L may not be heated as described above and may circulate through the load piping 31 by the circulating fluid circulation pump 32. In this case, the circulating fluid L at a low temperature continues to flow through the fan coil unit 36, and condensation may form inside the thermal valve V, causing the thermal valve V to malfunction. If the thermal valve V malfunctions, it may be necessary to disassemble the various parts and appliances inside the fan coil unit 36, or a current leak may occur, causing problems with the electrical equipment (for example, a breaker may trip).

Therefore, according to this embodiment, after the thermal valve V is opened based on the valve control signal (ON signal) as described above during the freeze prevention operation (see S105, S115 in FIG. 12), the terminal control unit 36b judges whether or not a predetermined first temperature condition is satisfied (see S117, S120 in FIG. 12). If the first temperature condition is not satisfied as a result of this judgment, it is considered that the circulating fluid L is not sufficiently heated due to some reason such as a malfunction in the heat pump unit 5, and the terminal control unit 36b performs forced control of the thermal valve V (see S130 in FIG. 12). This forced control controls the thermal valve V in priority to the control based on the valve control signal (ON signal) as described above. That is, regardless of whether the valve control signal to the terminal control unit 36b is a signal to open the thermal valve V or a signal to close the thermal valve V, the terminal control unit 36b can force the thermal valve V to be open or closed. By forcibly closing the thermal valve V through such forced control , it is possible to prevent the circulating fluid L at a low temperature from being supplied to the fan coil unit 36. As a result, it is possible to prevent the thermal valve V from failing due to the internal condensation.

In particular, in this embodiment, as described above, the first temperature condition is that the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than the first threshold value (-20°C in the above example) when the first predetermined time (20 minutes in the above example) has elapsed after the thermal valve V is opened by the terminal control unit 36b based on the valve control signal (ON signal).

Therefore, particularly in this embodiment, the terminal control unit 36b determines, as the first temperature condition, whether the first predetermined time has elapsed after the thermal valve V is opened based on a valve control signal (ON signal) and the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than the first threshold value (see S117, S120 in FIG. 12). This makes it possible to reliably identify whether the circulating fluid L remains unheated due to some reason on the heat pump unit 5 side during the freeze prevention operation.

In particular, in this embodiment, as described above, after the first temperature condition is not satisfied and the thermal valve V is closed (see S130 in FIG. 12), the terminal control unit 36b determines whether a predetermined second temperature condition is satisfied (see S131 to S136 in FIG. 12).

That is, particularly in this embodiment, even after the first temperature condition is not satisfied and the terminal control unit 36b closes the thermal valve V as described above, the terminal control unit 36b determines whether the second temperature condition is satisfied. As a result, even if the first temperature condition is not satisfied (S120: No) during the freeze prevention operation because the heat pump unit 5 does not initially heat the circulating fluid L due to reasons such as the outside air temperature being too low, if the heat pump unit 5 subsequently begins to heat the circulating fluid L sufficiently, the second temperature condition is satisfied (S136: Yes), and this can be clearly identified.

In particular, in this embodiment, as described above, the second temperature condition is that after the first temperature condition is not satisfied and the thermal valve V is closed by the terminal control unit 36b (see S130 in FIG. 12), the second predetermined time (60 minutes in the above example) has elapsed and the thermal valve V is opened by the terminal control unit 36b (see S132 and S133 in FIG. 12), and then the third predetermined time (5 minutes in the above example) has elapsed (see S135 in FIG. 12), and the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than the second threshold value (-20°C in the above example).

Therefore, in this embodiment, in particular, the terminal control unit 36b determines, as the second temperature condition, whether the temperature of the circulating fluid L detected by the water temperature sensor 36c is equal to or higher than the second threshold value when the second predetermined time has elapsed after the thermal valve V is closed by the terminal control unit 36b and the thermal valve V is opened again, and the third predetermined time has elapsed (see S130, S132, S133, and S135 in FIG. 12). This makes it possible to reliably identify whether the heat pump unit 5 did not initially heat the circulating fluid L during the freeze prevention operation, but that the heat pump unit 5 has started to heat the circulating fluid L sufficiently as time passes.

Furthermore, particularly in this embodiment, as described above, when the second temperature condition is satisfied (see S136 in Figure 12), the terminal control unit 36b terminates the forced control (see S165 in Figure 12) in response to the valve control signal (OFF signal) from the terminal remote control 71 or the valve control signal (OFF signal) input from the heat pump control device 62 via the second terminal control line 145 corresponding to the end of the anti -freeze operation (see S160 in Figure 12).

That is, particularly in this embodiment, when it is determined that the second temperature condition is satisfied, it is deemed that the circulating fluid L has been sufficiently heated over time as described above. In this case, the terminal control unit 36b continues the forced control , but when the valve control signal (OFF signal) is input from the heat pump control device 62 via the second terminal control line 145 or when the valve control signal (OFF signal) is transmitted from the terminal remote control 71 in response to the end of the freeze prevention operation, the terminal control unit 36b ends the forced control . As a result, when the freeze prevention operation on the heat pump unit 5 side is ended or when the user appropriately operates the terminal remote control 71, the forced control is ended and normal opening and closing control of the thermal valve V by the heat pump control device 62 is resumed, and the thermal valve V can be opened.

In particular, in this embodiment, when the second temperature condition is not satisfied (see S136 in FIG. 12), the terminal control unit 36b ends the forced control (see S150 in FIG. 12) in response to the valve control signal from the terminal remote control 71 (see S145 in FIG. 12). In other words, when it is determined that the second temperature condition is not satisfied, it is not the case that the circulating fluid L has been sufficiently heated over time as described above, and it is therefore deemed that some abnormality, such as a failure, has occurred in the heat pump unit 5. As a result, the terminal control unit 36b continues the forced control , and the thermal valve V can be maintained in a closed state.

However, the terminal control unit 36b ends the forced control only when the valve control signal is transmitted from the terminal remote control 71. Therefore, if the user appropriately operates the terminal remote control 71 while being aware of some abnormality in the heat pump unit 5, the user can end the forced control and return to the normal opening and closing control of the thermal valve V by the heat pump control device 62, thereby opening the thermal valve V.

<Modification>
In the above, the anti-freezing operation (2) is performed after the anti-freezing operation (1). However, the anti-freezing operation (2) may be performed without performing the anti-freezing operation (1).

In the above, an example has been described in which the second heat exchanger 51 is disposed upstream of the first heat exchanger 41 with respect to the flow of the circulating circulating fluid L in the terminal circulation circuit 30, but this is not limited thereto, and the first heat exchanger 41 may be disposed upstream of the second heat exchanger 51. Furthermore, the first heat exchanger 41 and the second heat exchanger 51 may be connected in parallel in the terminal circulation circuit 30.

In the above, the rotation speed of the compressor 53 is controlled in accordance with the forward temperature of the circulating fluid L detected by the second forward temperature sensor 35 on the outlet side (outlet side) of the second heat exchanger 51, that is, so-called forward temperature control is performed, but this is not limited to this. The rotation speed of the compressor 53 may be controlled in accordance with the return temperature of the circulating fluid L detected by the return temperature sensor 34 on the inlet side (inlet side) of the second heat exchanger 51, that is, so-called return temperature control may be performed.

In the above embodiment, the refrigerant circulation circuit 50, which is a heat source, is connected to the second heat exchanger 51, which is a heating heat exchanger, and the circulating liquid L is heated by heat exchange between the refrigerant C2 heated by the refrigerant circulation circuit 50 and supplied to the second heat exchanger 51 and the circulating liquid L, but this is not limited to the above. That is, the circulating liquid L may be heated in the heating heat exchanger using heat from another appropriate heat source other than the heat pump. An example of another heat source is, for example, the hot water circulation circuit 40, which can supply hot water heated by receiving heat from the gas heater 43 to the heating heat exchanger (in this case, the first heat exchanger 41). Furthermore, in the above embodiment, the case where one heat exchange terminal is connected is described as an example, but this is not limited to the above. That is, a configuration in which two or more heat exchange terminals are connected may be used. In these cases, the same effects as those of the above embodiment can be obtained.

Furthermore, the flowcharts shown in Figures 10 and 12 do not limit the present invention to the procedures shown in the above flows, and procedures may be added or deleted or the order may be changed without departing from the spirit and technical concept of the invention.

In addition to what has already been described above, the methods according to the above embodiments and their variations may be used in appropriate combinations.

Although we will not provide examples, the present invention can be implemented with various modifications without departing from the spirit of the invention.

1 Hot water heating system 5 Heat pump unit (outdoor unit)
30 Terminal circulation circuit (liquid circulation circuit)
31 Load piping (circulating fluid piping)
32 Circulating fluid circulation pump (circulating pump)
36 Fan coil unit (indoor unit)
36a Heat exchanger (indoor heat exchanger)
36b Terminal control unit 36d Blower fan 36c Water temperature sensor (sensor)
50 Refrigerant circulation circuit (heat source)
51 Second heat exchanger (heating heat exchanger)
51b Circulating fluid passage 62 Heat pump control device (heat source control unit)
71 Terminal remote control (remote control)
144 First terminal control line 145 Second terminal control line L Circulating fluid V Thermal valve (on-off valve)

Claims (6)

a fan coil unit including an indoor heat exchanger that exchanges heat between indoor air in a space to be air-conditioned and a circulating fluid, a blower fan for causing the heat exchange in the indoor heat exchanger, a sensor that detects the temperature of the circulating fluid flowing through the indoor heat exchanger, an on-off valve that can open and close a flow passage of the circulating fluid, and a terminal control unit that controls the on-off valve and the blower fan;
an outdoor unit including a heating heat exchanger having a circulating fluid passage and heating the circulating fluid in the circulating fluid passage by a heat source, a circulating pump for circulating the circulating fluid, and a heat source control unit for controlling the heat source and the circulating pump;
A first terminal control line for performing one-way communication from the terminal control unit to the heat source control unit;
having
a circulation fluid passage of the heating heat exchanger and the indoor heat exchanger are connected in a circular manner by a circulation fluid piping to form a liquid circulation circuit, and the hot water heating system is capable of performing a heating operation in which indoor air is heated by the fan coil unit,
Further comprising a second terminal control line for performing one-way communication from the heat source control unit to the terminal control unit;
The heat source control unit is
a freeze prevention control means for performing a freeze prevention operation in which, when the heating operation is not being performed, the circulation pump is started with the heat source being started, and the circulating liquid is circulated through the circulating liquid piping;
The terminal control unit
a first opening/closing control means for opening and controlling the opening/closing valve based on a valve control signal from a remote control for operating the fan coil unit or from the heat source control unit via the second terminal control line;
a first determination means for determining whether or not a predetermined first temperature condition is satisfied after the on-off valve is opened by the first on-off control means based on the valve control signal in response to the execution of the anti-freeze operation by the anti-freeze control means of the heat source control unit;
a second opening/closing control means for performing at least a process of forcibly controlling and closing the on-off valve by a forced control of the on-off valve executed in place of the opening control by the first opening /closing control means based on the valve control signal when the first temperature condition in the first determination means is not satisfied;
A hot water heating system comprising: The first temperature condition is
a circulating fluid temperature detected by the sensor is equal to or higher than a first threshold value when a first predetermined time has elapsed since the first on-off control means opened the on-off valve based on the valve control signal;
2. The hot water heating system according to claim 1, The terminal control unit
The hot water heating system according to claim 1 or 2, further comprising a second judgment means for judging whether or not a predetermined second temperature condition is satisfied after the first temperature condition in the first judgment means is not satisfied and the second opening /closing control means closes the opening/closing valve by the forced control. The second temperature condition is
when the first temperature condition in the first determination means is not satisfied and the second opening/closing control means controls the opening/ closing valve by the forced control , a second predetermined time elapses and the second opening/closing control means controls the opening/closing valve by the forced control , and when a third predetermined time has elapsed thereafter, the circulating fluid temperature detected by the sensor becomes equal to or higher than a second threshold value;
4. The hot water heating system according to claim 3, When the second temperature condition in the second determination means is satisfied, the second opening/closing control means
The hot water heating system of claim 3 or claim 4, characterized in that the forced control is terminated in response to the valve control signal from the remote control or the valve control signal input from the heat source control unit via the second terminal control line in response to the termination of the anti -freeze operation by the anti-freeze control means. When the second temperature condition in the second determination means is not satisfied, the second opening/closing control means
6. The hot water heating system according to claim 3, wherein the forced control is terminated in response to the valve control signal from the remote controller.

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