JP7475297B2 - Fluid circulation heating system - Google Patents

Description

The present invention relates to a fluid circulation heating system.

In a fluid circulation heating system such as a hot water heating system, for example, as shown in Patent Document 1, a system is known that includes a first circulation circuit to which a heat pump and a heating device are connected, a second circulation circuit to which a gas heater is connected, and a heat exchanger that exchanges heat between the fluids circulating in each of the first and second circulation circuits by operating the pump.

In this system, the fluid flowing via the heating device on the first circulation circuit side can be heated by operating the heat pump, and by performing heat exchange (heat transfer) from the fluid on the second circulation circuit side heated by operating the gas heater to the fluid on the first circulation circuit side via the heat exchanger, it is also possible to heat the fluid flowing via the heating device on the first circulation circuit side by operating the gas heater.

JP 2020-159663 A

In a fluid circulation heating system such as that shown in Patent Document 1, the first circulation circuit connected to the heat pump has a portion that passes through the outdoor unit, which is the main body of the heat pump, located outdoors, so in winter, etc., it is necessary to prevent the circulating fluid, such as water, in the first circulation circuit from freezing.

In this case, anti-freezing methods that can be used include, for example, a method of circulating the fluid in the first circulation circuit while operating a heat pump to heat the fluid on the first circulation circuit side (first method), or a method of circulating the fluid in the first circulation circuit and operating a combustion heating device such as a gas heater while operating the fluid in the first circulation circuit and the second circulation circuit to heat the fluid on the first circulation circuit side via the fluid on the second circulation circuit side (second method).

However, with the first method, it is difficult to sufficiently heat the fluid on the first circulation circuit side by operating the heat pump when the outside air temperature is very low. Also, with the second method, the energy costs for preventing freezing tend to be high.

The present invention has been made in view of this background, and aims to provide a fluid circulation heating system that has a first circulation circuit to which a heat pump is connected and a second circulation circuit to which a combustion heating device is connected, and that can prevent freezing on the first circulation circuit side by appropriately selectively operating the heat pump and the combustion heating device.

In order to achieve the above object, the fluid circulation heating system of the present invention comprises a first circulation circuit having a first pump and circulating a first fluid by operation of the first pump, a heat pump connected to the first circulation circuit so as to heat the first fluid circulating in the first circulation circuit, a second circulation circuit having a second pump and circulating a second fluid by operation of the second pump, a combustion type heating device connected to the second circulation circuit so as to heat the second fluid circulating in the second circulation circuit, and a heat exchanger connected to the first circulation circuit and the second circulation circuit so as to exchange heat between the first fluid circulating in the first circulation circuit and the second fluid circulating in the second circulation circuit,
A first temperature sensor that detects an outside air temperature;
a control device having a function of executing a freeze prevention operation control, which is an operation control for preventing freezing of the first fluid in the first circulation circuit, when a predetermined first condition is satisfied, the operation control including at least a condition that a detection value of the outside air temperature by the first temperature sensor is equal to or lower than a predetermined first threshold temperature,
The control device is configured to selectively execute, as the freeze prevention operation control, a first operation control that operates the first pump and the heat pump while the operation of the second pump and the combustion heating device is stopped, and a second operation control that operates the first pump, the second pump, and the combustion heating device while the operation of the heat pump is stopped, and is configured to execute the first operation control with the necessary condition that the detected value of the outside air temperature is equal to or higher than a predetermined second threshold temperature that is lower than the first threshold temperature, and to execute the second operation control with the necessary condition that the detected value of the outside air temperature is equal to or lower than the predetermined second threshold temperature ( Reference Invention 1 ).
In the present invention, when the detected value of the outside air temperature coincides with the second threshold temperature, either the first operational control or the second operational control may be executed.

According to the first reference invention , in a situation where the detected value of the outside air temperature is lower than the second threshold temperature, the first operation control for operating the heat pump is not executed as the freeze prevention operation control, and the second operation control for operating the combustion heating device is executed. Therefore, in a situation where it is difficult for the heat pump to heat the first fluid due to the low outside air temperature, the second operation control for operating the combustion heating device is executed, so that the first fluid in the first circulation circuit can be appropriately heated.

In addition, in a situation where the detected value of the outside air temperature is higher than the second threshold temperature, the second operation control for operating the combustion heating device is not executed as the anti-freeze operation control, and the first operation control for operating the heat pump may be executed. Therefore, in a situation where the outside air temperature is not so low and the heat pump can generate sufficient heat to heat the first fluid, the first operation control for operating the heat pump is executed, thereby making it possible to appropriately heat the first fluid in the first circulation circuit and to reduce the energy cost for heating the first fluid.

Therefore, according to the first aspect of the present invention , by appropriately selectively operating the heat pump and the combustion heating device, freezing on the first circulation circuit side can be prevented.

In the above -mentioned Reference Invention 1 , the control device may be configured to selectively execute a third operation control as the freeze prevention operation control, which operates the first pump while the heat pump, the combustion heating device, and the second pump are stopped. In this case, it is preferable that the control device is configured to start the third operation control when the freeze prevention operation control is started, and then start the first operation control or the second operation control when a predetermined second condition is satisfied ( Reference Invention 2 ).

According to this, after the freeze prevention operation control is started, the third operation control is executed to operate the first pump without operating the combustion heating device and the heat pump until the specified second condition is satisfied (until a situation arises in which it is necessary to execute the first operation control or the second operation control), so that in a situation in which freezing of the first fluid can be prevented by the third operation control, energy consumption in the freeze prevention operation control can be reduced.

In the above -mentioned Reference Invention 2 , a second temperature sensor is further provided for detecting the temperature of the first fluid, and it is preferable that the specified second condition includes at least a condition that the temperature of the first fluid detected by the second temperature sensor is lower than a specified third threshold temperature ( Reference Invention 3 ).
According to this, while the third operation control is being executed, the first operation control or the second operation control can be started at an appropriate timing to prevent the first fluid from freezing, thereby making it possible to heat the first fluid.

In the above -mentioned Reference Inventions 1 to 3 , it is preferable that the control device further includes a third temperature sensor for detecting the temperature of the first fluid, and that the control device is configured to stop the first operation control or the second operation control when the temperature of the first fluid detected by the third temperature sensor becomes equal to or higher than a predetermined fourth threshold temperature after the start of the first operation control or the second operation control ( Reference Invention 4 ). Note that when Reference Invention 4 is combined with Reference Invention 3 , the third temperature sensor may be the same temperature sensor as the second temperature sensor.

This allows the first operation control or the second operation control to be executed until the temperature of the first fluid is sufficiently increased, so that it is possible to prevent a situation in which the first operation control for operating the heat pump or the second operation control for operating the combustion heating device is frequently and repeatedly executed to prevent the first fluid from freezing. As a result, it is possible to suppress the progression of deterioration of the heat pump or the combustion heating device.

In the above -mentioned Reference Invention 4 , it is preferable that the control device is configured to execute a third operation control for operating the first pump in a state where the operations of the heat pump, the combustion type heating device, and the second pump are stopped when the first operation control or the second operation control is stopped ( Reference Invention 5 ). Note that Reference Invention 5 can also be combined with Reference Invention 2 , and in that case, the third operation control in Reference Invention 5 means the same operation control as the third operation control in Reference Invention 2 .

According to this, after the first operation control or the second operation control is stopped, the third operation control is executed to operate the first pump without operating the combustion heating device and the heat pump, so that the entire first fluid in the first circulation circuit is warmed by preheating for a while. Therefore, it is possible to suppress the energy consumption for preventing the first fluid from freezing, and to prevent the first fluid in the flow path on the outdoor side of the first circulation circuit from being suddenly cooled and becoming easily frozen .
In light of the above, a more specific fluid circulation heating system of the present invention is a fluid circulation heating system comprising: a first circulation circuit having a first pump and circulating a first fluid by operation of the first pump; a heat pump connected to the first circulation circuit so as to heat the first fluid circulating in the first circulation circuit; a second circulation circuit having a second pump and circulating a second fluid by operation of the second pump; a combustion type heating device connected to the second circulation circuit so as to heat the second fluid circulating in the second circulation circuit; and a heat exchanger connected to the first circulation circuit and the second circulation circuit so as to perform heat exchange between the first body circulating in the first circulation circuit and the second fluid circulating in the second circulation circuit,
A first temperature sensor that detects an outside air temperature;
A second temperature sensor that detects a temperature of the first fluid;
a control device having a function of executing a freeze prevention operation control, which is an operation control for preventing freezing of the first fluid in the first circulation circuit, when a predetermined first condition is satisfied, the operation control including at least a condition that a detection value of the outside air temperature by the first temperature sensor is equal to or lower than a predetermined first threshold temperature,
The control device is configured to selectively execute, as the freeze prevention operation control, a first operation control for operating the first pump and the heat pump while the operation of the second pump and the combustion type heating device is stopped, a second operation control for operating the first pump, the second pump, and the combustion type heating device while the operation of the heat pump is stopped, and a third operation control for operating the first pump while the operation of the heat pump, the combustion type heating device, and the second pump is stopped, and is configured to start the third operation control when starting the freeze prevention operation control in response to the first condition being satisfied, and then execute the first operation control with a necessary condition that the detected value of the outside air temperature is equal to or higher than a predetermined second threshold temperature lower than the first threshold temperature and the temperature of the first fluid measured by the second temperature sensor is lower than a predetermined third threshold temperature, and to execute the second operation control with a necessary condition that the detected value of the outside air temperature is equal to or lower than the second threshold temperature and the temperature of the first fluid measured by the second temperature sensor is lower than the third threshold temperature,
Furthermore, the first circulation circuit is a circulation circuit capable of connecting a specific heating device, which is a heating device having a flow path through which a first fluid circulates in the first circulation circuit flows, and at least a part of the flow path is disposed outdoors;
The third threshold temperature is set to a temperature higher when the specific heating device is connected to the first circulation circuit than when the specific heating device is not connected (first invention).
In the first invention, the apparatus further includes a third temperature sensor that detects a temperature of the first fluid,
It is preferable that the control device is configured to stop the first operation control or the second operation control when, after the start of the first operation control or the second operation control, the detection value of the temperature of the first fluid by the third temperature sensor becomes a temperature equal to or higher than a predetermined fourth threshold temperature (second invention).
In the second invention described above, it is preferable that the control device is configured to execute the third operational control when the first operational control or the second operational control is stopped (a third invention).

1 is a diagram showing the overall configuration of a heating system as a fluid circulation heating system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration related to control of the heating system according to the embodiment. 3 is a flowchart showing a process of the control device shown in FIG. 2 . 4 is a flowchart showing the process of the antifreeze operation control in STEP 4 of FIG. 3 .

One embodiment of the present invention will be described below with reference to Figures 1 to 4. As shown in Figure 1, the fluid circulation heating system 1 of this embodiment is a heating system that includes a heating device 2 that heats an indoor space as a heat dissipation device, and also includes a combustion heat source unit 3 and a heat pump unit 4 that are respectively equipped with a combustion heating device 30 and a heat pump 40 as multiple (two) heat sources for heating the fluid to be passed through the heating device 2. Hereinafter, the fluid circulation heating system 1 will be referred to as the heating system 1.

In the illustrated heating system 1, the heating device 2 includes a first heating device 2a such as a panel radiator or a floor heater, and a second heating device 2b such as a fan coil unit. The first heating device 2a is a heating device in which a flow path (not shown) for the heating fluid is disposed indoors. The second heating device 2b is a heating device in which at least a portion of a flow path (not shown) for the heating fluid is disposed outdoors.

However, the heating system 1 may include only one of the first heating device 2a and the second heating device 2b. Furthermore, each of the first heating device 2a and the second heating device 2b is not limited to being a single heating device, and may be multiple.

The heating system 1 also includes a first circulation circuit 5 that circulates a fluid (hereinafter referred to as a first fluid) to be passed through the heating device 2, and a second circulation circuit 6 that circulates a second fluid in a flow path independent of the first circulation circuit 5.

In this embodiment, the heat pump 40 is a heat source capable of directly heating the first fluid circulating in the first circulation circuit 5 during the circulation of the first fluid. On the other hand, the combustion heating device 30 is a heat source that heats the second fluid circulating in the second circulation circuit 6, and indirectly heats the first fluid via the second fluid by heat exchange between the second fluid and the first fluid circulating in the first circulation circuit 5 (heat transfer from the second fluid to the first fluid).

For this reason, the heating system 1 further includes a heat exchanger unit 7 equipped with a heat exchanger 70 that performs heat exchange between the first fluid and the second fluid. Note that, as the first fluid and the second fluid, for example, water (water for heating), antifreeze, or other fluids may be used. In this embodiment, the combustion type heat source unit 3 and the heat exchanger unit 7 are units installed indoors, and the heat pump unit 4 is a unit installed outdoors.

The heat pump 40 mounted on the heat pump unit 4 is of a known configuration and includes a condenser 41 and a refrigerant circuit 42 including a compressor, an evaporator, and an expansion mechanism (not shown), and is configured to dissipate heat absorbed by the refrigerant from the outdoor air by the condenser 41. In this case, the condenser 41 includes a flow path (not shown) for flowing the refrigerant flowing in from the refrigerant circuit 42, as well as a flow path (not shown) for flowing the first fluid, and is configured to heat the first fluid by performing heat exchange between the refrigerant flowing through each flow path and the first fluid (heat transfer from the refrigerant to the first fluid).

The first circulation circuit 5 has an electric first pump 50 as a power source for moving the first fluid, and is configured to include a flow path for returning the first fluid flowing out of the condenser 41 of the heat pump 40 to the condenser 41 after passing through the heat exchanger 70 of the heat exchanger unit 7 and the heating device 2 (one or more of the first heating device 2a and the second heating device 2b) in order, a flow path for returning the first fluid flowing out of the condenser 41 to the condenser 41 after passing through the heating device 2 without passing through the heat exchanger 70 of the heat exchanger unit 7 (bypassing the heat exchanger 70), and a flow path for returning the first fluid flowing out of the condenser 41 to the condenser 41 without passing through the heating device 2.

Specifically, the first circulation circuit 5 includes a first flow path 51 arranged from the outlet of the flow path for the first fluid (not shown) of the condenser 41 of the heat pump 40 to the inlet of the flow path for the first fluid 70a of the heat exchanger 70 of the heat exchanger unit 7, a second flow path 52 arranged from the outlet of the flow path for the first fluid 70a of the heat exchanger 70 to the inlet of the flow path for the first fluid (not shown) provided in each heating device 2, and a third flow path 53 arranged from the outlet of the flow path for the first fluid of each heating device 2 to the inlet of the flow path for the first fluid of the condenser 41 of the heat pump 40. The system includes a third flow path 53, a first bypass path 54 that branches off from the middle of the first flow path 51 and is arranged to merge with the middle of the second flow path 52 without passing through the heat exchanger 70 (bypassing the heat exchanger 70), a bypass ratio adjustment valve 55 for adjusting the ratio between the flow rate of the first fluid passing through the flow path 70a of the heat exchanger 70 and the flow rate of the first fluid passing through the first bypass path 54, and a second bypass path 56 that branches off from a flow path downstream of the connection with the first bypass path 54 of the second flow path 52 and is arranged to merge with the third flow path 53 without passing through the heating device 2.

In this case, each heating device 2 (first heating device 2a and second heating device 2b) is connected in parallel between the second flow path 52 and the third flow path 53. A first pump 50 is interposed in any one of the first to third flow paths 51 to 53, for example, in the first flow path 51 upstream of the connection between the first flow path 51 and the first bypass path 54. In this embodiment, the first pump 50 is mounted in the heat pump unit 4, and the bypass ratio adjustment valve 55 is mounted in the heat exchanger unit 7.

In this embodiment, the bypass ratio adjustment valve 55 is a distribution valve interposed at the connection between the first flow path 51 and the first bypass path 54, and is capable of distributing the first fluid flowing in from the upstream side of the first flow path 51 to the heat exchanger 70 and the first bypass path 54, and is capable of variably adjusting the distribution ratio (the ratio between the flow rate of the first fluid distributed to the heat exchanger 70 and the flow rate of the first fluid distributed to the first bypass path 54). Such a bypass ratio adjustment valve 55 (distribution valve) is, for example, configured by an electrically operated three-way valve or the like.

As described above, the first circulation circuit 5 includes the first pump 50, the first to third flow paths 51 to 53, the first bypass path 54, the bypass ratio adjustment valve 55, and the second bypass path 56. Therefore, the flow path that returns the first fluid from the condenser 41 of the heat pump 40 to the condenser 41 after passing through the heat exchanger 70 of the heat exchanger unit 7 and the heating device 2 in order is configured as a flow path including the first flow path 51, the flow path 70a of the heat exchanger 70, the second flow path 52, a flow path (not shown) of the heating device 2 (one or more of the first heating device 2a and the second heating device 2b), and the third flow path 53.

The flow path for returning the first fluid from the condenser 41 of the heat pump 40 to the condenser 41 after bypassing the heat exchanger 70 of the heat exchanger unit 7 and passing through the heating device 2 is configured as a flow path including the first flow path 51 upstream of the bypass ratio adjustment valve 55, the first bypass path 54, a flow path of the second flow path 52 downstream of the connection with the first bypass path 54, a flow path (not shown) of the heating device 2 (one or more of the first heating device 2a and the second heating device 2b), and a third flow path 53.

The ratio between the flow rate of the first fluid passing through the heat exchanger 70 and the flow rate of the first fluid passing through the first bypass passage 54 can be variably adjusted by controlling the operation of the bypass ratio adjustment valve 55. Each heating device 2 (first heating device 2a and second heating device 2b) is equipped with an on-off valve (not shown) such as a thermal valve or solenoid valve that can open and close the flow path (flow path for the first fluid). Therefore, the flow path passing through each heating device 2 is a flow path that opens when the on-off valve is controlled to be open.

The flow path that returns the first fluid from the condenser 41 of the heat pump 40 to the condenser 41 without passing through the heating device 2 is configured as a flow path that includes the first flow path 51 upstream of the bypass ratio adjustment valve 55, the first bypass path 54 or the flow path 70a of the heat exchanger 70, the flow path of the second flow path 52 between the connection part with the first bypass path 54 and the connection part with the second bypass path 56, the second bypass path 56, and the third flow path 53.

Additionally, the first circulation circuit 5 may not include, for example, the first bypass passage 54 and the bypass ratio adjustment valve 55. Also, for example, the first circulation circuit 5 may include a flow control valve for controlling the flow rate of the first fluid passing through the second bypass passage 56.

Temperature sensors 81, 82 for detecting the temperature of the first fluid are installed in the first circulation circuit 5. Furthermore, a temperature sensor 83 for detecting the outside air temperature (ambient temperature around the heat pump 40) is installed in the heat pump unit 4. Note that the temperature sensor 83 may be provided separately from the heat pump unit 4.

The temperature sensor 81 is a sensor for detecting the temperature of the first fluid (the first fluid heated by the condenser 41) flowing out of the condenser 41 of the heat pump 40, and is attached to the first flow path 51 upstream of the bypass ratio adjustment valve 55. Hereinafter, the temperature of the first fluid detected by the temperature sensor 81 is referred to as the HP outflow temperature.

The temperature sensor 82 is a sensor for detecting the temperature of the first fluid flowing into the condenser 41 of the heat pump 40, and is attached to the third flow path 53 (the third flow path 53 downstream of the confluence of the first fluids flowing out of each heating device 2). Hereinafter, the temperature of the first fluid detected by the temperature sensor 82 is referred to as the HP inlet temperature.

The combustion heating device 30 mounted on the combustion heat source unit 3 is of known configuration and includes a burner 31 that burns fuel gas (or liquid fuel such as kerosene) supplied from a fuel supply device (not shown), and a heat exchanger 32 that is heated by the combustion heat of the burner 31. The combustion exhaust gas from the burner 31 is discharged to the outdoors via an exhaust path (not shown).

The heat exchanger 32 has a flow path 32a for the second fluid, and this flow path 32a is connected to the heat exchanger 70 of the heat exchanger unit 7 via the second circulation circuit 6. In this case, the second circulation circuit 6 includes an electric second pump 60 as a power source for moving the second fluid, an eleventh flow path 61 arranged so as to extend from the outlet of the flow path 32a of the heat exchanger 32 of the combustion heating device 30 to the inlet of the flow path 70b for the second fluid of the heat exchanger 70 of the heat exchanger unit 7, and a twelfth flow path 62 arranged so as to extend from the outlet of the flow path 70b for the second fluid of the heat exchanger 70 of the heat exchanger unit 7 to the inlet of the flow path 32a of the heat exchanger 32 of the combustion heating device 30, and the second pump 60 is interposed in one of the eleventh flow paths 61 and the twelfth flow path 62, for example, the twelfth flow path 62.

Therefore, by operating the second pump 60 and performing the combustion operation of the burner 31, the second fluid circulates between the heat exchanger 32 of the combustion heating device 30 and the heat exchanger 70 of the heat exchanger unit 7, and is heated in the heat exchanger 32, and the heated second fluid is supplied to the heat exchanger 70 of the heat exchanger unit 7.

In this embodiment, the second pump 60 is mounted on the combustion heat source unit 3. The heat exchanger unit 7 is also equipped with an on-off valve 71 such as a thermal valve or solenoid valve that can open and close one of the eleventh flow path 61 on the upstream side of the flow path 70b for the second fluid of the heat exchanger 70 and the twelfth flow path 62 on the downstream side, for example, the twelfth flow path 62. Therefore, the flow path that passes through the flow path 70b for the second fluid of the heat exchanger 70 of the heat exchanger unit 7 is a flow path that is opened when the on-off valve 71 is controlled to be open.

Additionally, the configuration of the second circulation circuit 6 is not limited to the above configuration. For example, the second circulation circuit may be configured to further include a bypass passage that allows the second fluid returning from the heat exchanger 70 of the heat exchanger unit 7 to the combustion heat source unit 3 to bypass the heat exchanger 32 of the combustion heating device 30 from the 12th flow path 62 and flow to the 11th flow path 61. In addition, for example, the second fluid discharged from the second pump 60 may be distributed to the heat exchanger 32 of the combustion heating device 30 and the heat exchanger 70 of the heat exchanger unit 7, and the second fluid flowing out from each of these heat exchangers 32 and 70 may be merged and then returned to the second pump 60.

In addition, in the heating system 1 of this embodiment, the combustion heat source unit 3, the heat pump unit 4, and the heat exchanger unit 7 are each provided as separate units, but two or more of these may be configured as a single unit. For example, the heat exchanger unit 7 may be incorporated into the combustion heat source unit 3 or the heat pump unit 4. In addition, the combustion heat source unit 3 may be configured to include, for example, a function as a hot water supply device.

2, the heating system 1 further includes a control device 90 that controls the operation of the heating system 1, and a remote control 100 for the user to operate the heating system 1. The control device 90 is configured with one or more electronic circuit units including, for example, a processor such as a microcomputer (not shown), a memory (RAM, ROM, etc.), an interface circuit, a communication circuit, etc. For example, the control device 90 can be configured as a collection of multiple electronic circuit units that are mounted on each heating device 2 (each of the first heating device 2a and the second heating device 2b), the combustion type heat source unit 3, the heat pump unit 4, and the heat exchanger unit 7, and can communicate with each other and cooperate to control the operation of the heating system 1. In this case, the collection of electronic circuit units may be configured so that one of the electronic circuit units functions as a higher-level control device that controls the overall operation of the heating system 1, and the other electronic circuit units function as control devices that control the local operation of each heating device 2, the combustion type heat source unit 3, the heat pump unit 4, and the heat exchanger unit 7.

The control device 90 receives sensing signals (detection signals) from a number of sensors, such as the temperature sensors 81 to 83, provided in the heating system 1. The control device 90 can also communicate with the remote control 100 via wired or wireless communication. Through this communication, the control device 90 can receive command information related to the operation of the heating device 2 from the remote control 100, and can transmit various notification information to the remote control 100 for output. The heating system 1 is not limited to having one remote control 100, and may have multiple remote controls.

The control device 90 controls the operation of each of the controlled elements of the heating device 2, the combustion heat source unit 3, the heat pump unit 4, and the heat exchanger unit 7 through functions realized by the implemented hardware configuration and program (software configuration).

In this case, the controlled elements of each heating device 2 include an on-off valve (not shown) that opens and closes the flow path (flow path for flowing the first fluid) of the heating device 2. The controlled elements of the combustion heat source unit 3 include the burner 31 and the second pump 60. The combustion operation of the burner 31 is controlled through the operation control of an ignition device, a fuel supply device, and a combustion fan for supplying combustion air (not shown). The controlled elements of the heat pump unit 4 include the first pump 50 and the compressor (not shown) of the refrigerant circuit 42. The controlled elements of the heat exchanger unit 7 include the on-off valve 71 and the bypass ratio adjustment valve 55.

Next, the operation of the heating system 1 of this embodiment will be described. In the heating system 1 of this embodiment, the control device 90 controls the operation of one or both of the heat pump 40 and the combustion heating device 30 so that the temperature of the first fluid supplied to the heating device 2 in the first circulation circuit 5 during heating operation (heat dissipation operation) of each heating device 2 matches or nearly matches a target temperature determined according to the target heating temperature set by the user using the remote control 100, while operating the first pump 50 to circulate the first fluid in the first circulation circuit 5.

In this case, when operating the combustion heating device 30 (burner 31 combustion operation), the control device 90 operates the first pump 50, and also operates the second pump 60 while controlling the opening and closing valve 71 of the heat exchanger unit 7 to be open, thereby circulating the second fluid in the second circulation circuit 6, and controls the bypass ratio adjustment valve 55 to open the flow path 70a for the first fluid of the heat exchanger 70 to the upstream first flow path 51.

In this case, the bypass ratio adjustment valve 55 may be controlled to close the first bypass passage 54 of the first circulation circuit 5, but the bypass ratio adjustment valve 55 may also be controlled to open both the flow passage 70a of the heat exchanger 70 and the first bypass passage 54 to the upstream first flow passage 51.

In addition, when the outside air temperature is low, the control device 90 executes anti-freeze operation control processing to prevent the first fluid in the first circulation circuit 5 (mainly the first fluid in the portion of the first circulation circuit 5 that is disposed outdoors) from freezing while the heating operation of the heating device 2 is stopped.

Specifically, when the heating system 1 is in an operable state, the control device 90 executes the process shown in the flowchart of FIG. 3 to sequentially determine whether or not to execute anti-freeze operation control. That is, in each of STEPs 1 to 3, the control device 90 executes a process (STEP 1) to determine whether data indicating the results of checking the piping connections of the heating system 1 has been input to memory, a process (STEP 2) to determine whether the heating operation of all heating devices 2 is stopped, and a process (STEP 3) to determine whether the outside air temperature detected by the temperature sensor 83 is lower than a predetermined threshold temperature T1a.

Here, with regard to the judgment process of STEP 1, the piping connections of the first circulation circuit 5 and the second circulation circuit 6 of the heating system 1 are checked by an operator or the like through a test run after the installation of the heating system 1, and if the piping connections are properly made, data indicating the confirmation results is stored and held in the control device 90. Then, if data indicating that the piping connections are properly made is stored and held in the control device 90, the judgment result of STEP 1 becomes positive.

The threshold temperature T1a in the judgment process of STEP 3 is a preset outside air temperature at which the first fluid in the first circulation circuit 5 is likely to freeze, and can be set to, for example, -10°C.

Then, if all the judgment results in STEPs 1 to 3 are positive, the control device 90 determines that the situation calls for anti-freeze operation control, and executes anti-freeze operation control in STEP 4. As a result, the control device 90 executes anti-freeze operation control in a situation where the heating operation of the heating device 2 is stopped and the outside air temperature (detected value) is lower than the threshold temperature T1a (-10°C) is basically satisfied.

If the result of any of the judgments in STEPs 1 to 3 is negative, the control device 90 determines that the situation does not call for anti-freeze operation control, and stops anti-freeze operation control in STEP 5. Note that the process shown in the flowchart in FIG. 3 is performed sequentially even when anti-freeze operation control is being executed.

Additionally, in this embodiment, the case where all of the judgment results in STEPs 1 to 3 are positive corresponds to the case where the predetermined first condition in the present invention is met. Furthermore, the temperature sensor 83 corresponds to the first temperature sensor in the present invention, and the threshold temperature T1a in STEP 3 corresponds to the first threshold temperature in the present invention. However, for example, the condition that the judgment result in STEP 1 is positive may be omitted. Furthermore, for example, the first condition may include a condition related to a change in the outside air temperature or a condition related to the temperature of the first fluid in the first circulation circuit 5.

In this embodiment, the freeze prevention operation control has three types of control modes: first operation control, second operation control, and third operation control. Here, the first operation control is a control mode in which the heat pump 40 and the first pump 50 are operated while the operation of the combustion heating device 30 and the second pump 60 is stopped. In other words, the first operation control is a control mode in which the first fluid is circulated in the first circulation circuit 5 and the first fluid is heated by operating the heat pump 40.

The second operation control is a control mode in which the combustion heating device 30, the second pump 60, and the first pump 50 are operated while the operation of the heat pump 40 is stopped. In other words, the second operation control is a control mode in which the second fluid is heated by operating the combustion heating device 30 while the first fluid is circulated in the first circulation circuit 5 and the second fluid is circulated in the second circulation circuit 6, and the first fluid is heated by performing heat exchange (heat transfer) from the second fluid to the first fluid in the heat exchanger 70.

The third operation control is a control mode in which the first pump 50 is operated while the heat pump 40, the combustion heating device 30, and the second pump 60 are stopped. In other words, the third operation control is a control mode in which the first fluid is circulated in the first circulation circuit 5 without being heated.

The control device 90 then executes the freeze prevention operation control process as shown in the flowchart of FIG. 4. Specifically, the control device 90 first operates the first pump 50 in STEP 11 (turns the first pump 50 ON). In this case, the heat pump 40, the combustion heating device 30, and the second pump 60 are maintained in a stopped state in STEP 11. This starts the third operation control as freeze prevention operation control.

In this third operation control, the on-off valve (not shown) of the first fluid flow path provided in each first heating device 2a included in the heating device 2 is maintained in a closed state, while the on-off valve (not shown) of the first fluid flow path provided in each second heating device 2b included in the heating device 2 is controlled to be open. In addition, the bypass ratio adjustment valve 55 is controlled to an operating position (hereinafter referred to as the heat exchanger fully open position) that opens the first fluid flow path 70a of the heat exchanger 70 to the upstream first flow path 51 and closes the first bypass path 54. Therefore, in the first circulation circuit 5, the first fluid flowing out from the condenser 41 of the heat pump 40 circulates so as to return to the condenser 41 via the first flow path 51, the flow path 70a of the heat exchanger 70, the second flow path 52, the second bypass path 56 or the flow path of the second heating device 2b, and the third flow path 53. This prevents the first fluid from freezing in the first circulation circuit 5.

Next, in STEP 12, the control device 90 determines whether the heating device 2 includes a second heating device 2b such as a fan coil unit. If the result of the determination in STEP 12 is positive (if the heating device 2 includes a second heating device 2b), the control device 90 sequentially executes a process in STEP 13 to determine whether the HP outlet temperature of the first fluid detected by the temperature sensor 81 has dropped to a temperature lower than a predetermined threshold temperature T2a until the result of the determination becomes positive.

In addition, if the judgment result in STEP 12 is negative (the heating device 2 does not include the second heating device 2b), the control device 90 sequentially executes a process in STEP 14 to judge whether the HP outlet temperature of the first fluid detected by the temperature sensor 81 has dropped to a temperature lower than a predetermined threshold temperature T2b, until the judgment result becomes positive.

Here, the judgment process in STEPs 13 and 14 is a judgment process that specifies whether or not to shift the freeze prevention operation control from the third operation control to the first operation control or the second operation control. When the heating device 2 includes the second heating device 2b, it is preferable to start heating the first fluid early in order to prevent condensation in the second heating device 2b, so the threshold temperature T2a in STEP 13 is set to a relatively high temperature, for example, 12°C.

On the other hand, when the heating device 2 does not include the second heating device 2b, there is less need to start heating the first fluid early compared to when the second heating device 2b is included, so the threshold temperature T2b in STEP 14 is set to a temperature lower than the threshold temperature T2a (12°C) in STEP 13, for example, -15°C.

In addition, in this embodiment, the temperature sensor 81 corresponds to the second temperature sensor in the present invention. The threshold temperature T2a or T2b in STEP 13 or 14 corresponds to the third threshold temperature in the present invention, and the case where the judgment result of STEP 13 or 14 is positive corresponds to the case where the predetermined second condition in the present invention is satisfied. In STEP 13 or 14, instead of comparing the detection value of the HP outlet side temperature of the first fluid with the threshold temperature T2a or T2b, it may be determined whether the temperature of another part of the first circulation circuit 5, for example, the detection value of the temperature of the first fluid in the second flow path 52 or the third flow path 53, is lower than the predetermined threshold temperature. In addition, the second condition may include, for example, a condition related to the temperature change of the first fluid, the outside air temperature, the change in the outside air temperature, or the elapsed time after the start of the execution of the third operation control, instead of or in addition to the condition of STEP 13 and 14 related to the temperature of the first fluid.

When the judgment result of STEP 13 or 14 becomes positive (when the HP outlet temperature falls below the threshold temperature T2a or T2b), the control device 90 next judges in STEP 15 whether the outside air temperature detected by the temperature sensor 83 has fallen below a predetermined threshold temperature T1b in order to determine whether the anti-freeze operation control should be shifted from the third operation control to the first operation control or the second operation control. The threshold temperature T1b in STEP 15 is an outside air temperature lower than the threshold temperature T1a (-10°C) in STEP 3 and is an outside air temperature near the limit at which the heat pump 40 can generate heat sufficient to heat the first fluid, for example -22°C. The threshold temperature T1b corresponds to the second threshold temperature in the present invention.

If the determination result in STEP 15 is positive (if the outside air temperature is < T1b (-22°C)), it is difficult to heat the first fluid by operating the heat pump 40, so in STEP 16, the control device 90 operates the combustion heating device 30 (combustion operation of the burner 31) and the second pump 60 (turning the combustion heating device 30 and the second pump 60 ON). In this case, the operation of the first pump 50 continues, and the heat pump 40 is maintained in a stopped state. In addition, the opening/closing valve 71 of the heat exchanger unit 7 is controlled to be open. As a result, the freezing operation control is shifted from the third operation control to the second operation control.

In this second operation control, as in the third operation control, the on-off valve (not shown) of the flow path for the first fluid provided in each first heating device 2a included in the heating device 2 is maintained in a closed state, and the on-off valve (not shown) of the flow path for the first fluid provided in each second heating device 2b included in the heating device 2 is maintained in an open state. In addition, the bypass ratio adjustment valve 55 is maintained in the heat exchanger fully open position.

Therefore, the circulation of the first fluid in the first circulation circuit 5 is performed in the same manner as in the third operation control. The first fluid is then heated in the heat exchanger 70 by heat transfer from the heated second fluid. In this case, the combustion amount of the burner 31 of the combustion heating device 30 is controlled to, for example, a constant combustion amount. By performing the second operation control in this manner, the first fluid in the first circulation circuit 5 is prevented from freezing.

While executing the second operational control as described above, the control device 90 sequentially executes in STEP 17 a process of determining whether the HP inlet temperature detected by the temperature sensor 82 has risen to a temperature equal to or higher than a predetermined threshold temperature T3a until the determination result becomes positive. The threshold temperature T3a is set to a temperature at which it takes a relatively long time for the first fluid to drop from a temperature equal to the threshold temperature T3a to a temperature at which the first fluid begins to freeze, for example 25°C, even if the outside air temperature is relatively low.

Then, when the determination result in STEP 17 becomes positive (when the HP inlet side temperature is equal to or higher than T3a (25° C.)), the control device 90 stops the operation of the combustion type heating device 30 and the second pump 60 in STEP 18 (turns off the combustion type heating device 30 and the second pump 60). In this case, the control device 90 executes the process from STEP 11 again while continuing the operation of the first pump 50. This ends the second operation control and resumes the third operation control (the anti-freeze operation control transitions from the second operation control to the third operation control).

If the determination result in STEP 15 is negative (if the outside air temperature is equal to or greater than T1b (-22°C)), the first fluid can be heated by operating the heat pump 40, and so the control device 90 operates the heat pump 40 in STEP 19 (turns the heat pump 40 ON). In this case, the operation of the first pump 50 continues, and the combustion heating device 30 and the second pump 60 are maintained in a stopped state. This causes the freezing operation control to transition from the third operation control to the first operation control.

In this first operation control, as in the third operation control, the on-off valve (not shown) of the flow path for the first fluid provided in each first heating device 2a included in the heating device 2 is maintained in a closed state, and the on-off valve (not shown) of the flow path for the first fluid provided in each second heating device 2b included in the heating device 2 is maintained in an open state. In addition, the bypass ratio adjustment valve 55 is controlled, for example, to the heat exchanger full open position. Therefore, the circulation of the first fluid in the first circulation circuit 5 is performed in the same manner as in the third operation control. Then, the first fluid is heated by the condenser 41 of the heat pump 40. In this case, the heat pump 40 performs, for example, operation control of the compressor (not shown) so that its output is maintained constant. By performing the first operation control in this manner, the first fluid in the first circulation circuit 5 is prevented from freezing.

In addition, in the first operation control, the bypass ratio adjustment valve 55 may be controlled to open both the flow path 70a of the heat exchanger 70 and the first bypass path 54, or to open only the first bypass path 54 to the upstream first flow path 51.

While executing the first operation control as described above, the control device 90 judges in STEP 20 whether the outside air temperature detected by the temperature sensor 83 is maintained at a temperature equal to or higher than the threshold temperature T1b (-22°C) as in STEP 15. If the judgment result in STEP 20 becomes negative, the control device 90 executes the process from STEP 16. Therefore, if the detected value of the outside air temperature falls to a temperature lower than the threshold temperature T1b (-22°C) while the first operation control is being executed, the second operation control is started (the anti-freeze operation control transitions from the first operation control to the second operation control).

If the determination result in STEP 20 is positive (if the outside air temperature is equal to or higher than T1b (-22°C)), the control device 90 continues the first operational control and determines in STEP 21 whether the HP inlet side temperature detected by the temperature sensor 82 has risen to a temperature equal to or higher than the threshold temperature T3a shown in STEP 17, and if the determination result is negative, the process from STEP 20 is repeated.

When the determination result in STEP 21 becomes positive (when the HP inlet temperature is equal to or greater than T3a (25°C)), the control device 90 stops the operation of the heat pump 40 in STEP 22 (turns the heat pump 40 OFF). In this case, the control device 90 executes the process from STEP 11 again while continuing the operation of the first pump 50. This ends the first operation control and resumes the third operation control (the anti-freeze operation control transitions from the first operation control to the third operation control).

Additionally, in this embodiment, the temperature sensor 82 corresponds to the third temperature sensor in the present invention, and the threshold temperature T3a corresponds to the fourth threshold temperature in the present invention. In STEPs 17 and 21, instead of comparing the detected value of the HP inlet side temperature of the first fluid with the threshold temperature T3a, it may be determined whether the temperature of another location in the first circulation circuit 5, for example the detected value of the temperature of the first fluid near the outlet of the flow path of the heating device 2, is equal to or higher than a predetermined threshold temperature, or it may be determined whether the HP outlet side temperature of the first fluid detected by the temperature sensor 81 is equal to or higher than a predetermined threshold temperature.

In the heating system 1 of this embodiment, the freeze prevention operation control is executed by the control device 90 as described above. According to this embodiment, in STEP 15, if the detected value of the outside air temperature is lower than the threshold temperature T1b (-22°C), the first operation control for operating the heat pump 40 is not executed, and the second operation control for operating the combustion heating device 30 is executed. Therefore, even in a situation where the outside air temperature is so low that it is difficult for the heat pump 40 to heat the first fluid, the first fluid can be appropriately heated and the first fluid can be prevented from freezing.

In addition, in STEP 15, if the detected value of the outside air temperature is higher than the threshold temperature T1b (-22°C), the second operation control for operating the combustion heating device 30 is not executed, and the first operation control for operating the heat pump 40 is executed. Therefore, at an outside air temperature at which the heat pump 40 can sufficiently heat the first fluid, the first fluid can be appropriately heated by operating the heat pump 40 to prevent it from freezing. This makes it possible to reduce the energy cost for preventing the first fluid from freezing.

In addition, in a situation where it is determined that freezing of the first fluid can be prevented without heating the first fluid by operating the heat pump 40 or the combustion heating device 30, a third operational control is executed in which the heat pump 40 and the combustion heating device 30 are not operated and the first pump 50 is operated, thereby minimizing the amount of energy consumed to prevent freezing of the first fluid.

The present invention is not limited to the embodiment described above, and other embodiments may be adopted. For example, in the above embodiment, the third operation control is provided as the anti-freeze operation control, but the third operation control may be omitted. In this case, the anti-freeze operation control may adopt an embodiment in which, for example, the processing of STEP 11 in FIG. 4 is omitted, and the operation of the first pump 50 is added in STEPs 16 and 19, and further, the operation of the first pump 50 is stopped in STEPs 18 and 22.

In addition, in the above embodiment, the heat exchanger 70 is provided upstream of the heating device 2 and downstream of the heat pump 40, but the heat exchanger 70 may be provided upstream of the heat pump 40.

1...Heating system (fluid circulation heating system), 5...First circulation circuit, 6...Second circulation circuit, 30...Combustion heating device, 40...Heat pump, 50...First pump, 60...Second pump, 70...Heat exchanger, 90...Control device, 81...Temperature sensor (second temperature sensor), 82...Temperature sensor (third temperature sensor), 83...Temperature sensor (first temperature sensor).

Claims (3)

A fluid circulation heating system comprising: a first circulation circuit having a first pump and circulating a first fluid by operation of the first pump; a heat pump connected to the first circulation circuit so as to heat the first fluid circulating in the first circulation circuit; a second circulation circuit having a second pump and circulating a second fluid by operation of the second pump; a combustion type heating device connected to the second circulation circuit so as to heat the second fluid circulating in the second circulation circuit; and a heat exchanger connected to the first circulation circuit and the second circulation circuit so as to exchange heat between a first body circulating in the first circulation circuit and a second fluid circulating in the second circulation circuit,
A first temperature sensor that detects an outside air temperature ;
A second temperature sensor that detects a temperature of the first fluid;
a control device having a function of executing a freeze prevention operation control, which is an operation control for preventing freezing of the first fluid in the first circulation circuit, when a predetermined first condition is satisfied, the operation control including at least a condition that a detection value of the outside air temperature by the first temperature sensor is equal to or lower than a predetermined first threshold temperature,
The control device is configured to selectively execute, as the freeze prevention operation control, a first operation control for operating the first pump and the heat pump while the operation of the second pump and the combustion type heating device is stopped, a second operation control for operating the first pump, the second pump, and the combustion type heating device while the operation of the heat pump is stopped, and a third operation control for operating the first pump while the operation of the heat pump, the combustion type heating device, and the second pump is stopped, and is configured to start the third operation control when starting the freeze prevention operation control in response to the first condition being satisfied, and then execute the first operation control with a necessary condition that the detected value of the outside air temperature is equal to or higher than a predetermined second threshold temperature lower than the first threshold temperature and the temperature of the first fluid measured by the second temperature sensor is lower than a predetermined third threshold temperature, and to execute the second operation control with a necessary condition that the detected value of the outside air temperature is equal to or lower than the second threshold temperature and the temperature of the first fluid measured by the second temperature sensor is lower than the third threshold temperature ,
Furthermore, the first circulation circuit is a circulation circuit capable of connecting a specific heating device, which is a heating device having a flow path through which a first fluid circulates in the first circulation circuit flows, and at least a part of the flow path is disposed outdoors;
A fluid circulation heating system characterized in that the third threshold temperature is set to a higher temperature when the specific heating device is connected to the first circulation circuit than when the specific heating device is not connected . 2. The fluid circulation heating system according to claim 1 ,
A third temperature sensor is further provided to detect a temperature of the first fluid.
The control device is configured to stop the first operation control or the second operation control when the temperature of the first fluid detected by the third temperature sensor becomes equal to or higher than a predetermined fourth threshold temperature after the start of the first operation control or the second operation control. 3. The fluid circulation heating system according to claim 2 ,
The fluid circulation heating system, wherein the control device is configured to execute the third operation control when the first operation control or the second operation control is stopped.

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