Hot water supply system

Abstract

To provide a technique for improving energy saving property while facilitating securing an installation space and storage by suppressing both a hot water storage capacity of a hot water storage tank and a thermal capability of a heat source part in a good balance, with respect to a hot water supply system which includes a hot water circulation circuit for circulating hot water between the heat source part and each hot water supply destination.SOLUTION: A hot water supply system includes an open type hot water storage tank, and hot water supply mode switching means capable of switching a hot water supply mode, and has a sealed type hot water supply mode and an open type hot water supply mode as the hot water supply mode. The sealed type hot water supply mode is a hot water supply mode of turning a state of a hot water circulation circuit to a sealed state of being separated from the hot water storage tank, and circularly supplying hot water heated by a heat source part to each hot water supply destination by the operation of a circulation pump provided in the hot water circulation circuit. The open type hot water supply mode is a hot water supply mode of turning a state of the hot water circulation circuit to an open state of being connected to the hot water storage tank, and once storing hot water heated by the heat source part in the hot water storage tank, and circularly supplying to each hot water supply destination by the operation of the circulation pump provided in the hot water circulation circuit.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a hot water supply system equipped with a hot water circulation circuit that circulates hot water between a heat source unit and each hot water supply destination. [Background technology]

[0002] BACKGROUND ART Patent documents 1 and 2 disclose known hot water supply systems equipped with a hot water circulation circuit that circulates hot water between a heat source that heats hot water and each hot water supply destination that consumes the hot water. The hot water supply system described in Patent Document 1 is a sealed hot water supply system in which the hot water circulation circuit is sealed and not open to the atmosphere during operation. In such a sealed hot water supply system, hot water heated in a heat source is circulated and supplied to each hot water supply destination by the operation of a circulation pump provided in the sealed hot water circulation circuit, so the hot water transport power of the circulation pump only needs to cover the pressure loss in the hot water circulation circuit, reducing the transport power and improving energy conservation. On the other hand, the hot water supply system described in Patent Document 2 is an open-type hot water supply system in which the hot water circulation circuit is kept open through an open-type hot water storage tank during operation. In such an open-type hot water supply system, hot water heated by a heat source unit is temporarily stored in the hot water storage tank by operating a pressure pump provided in the open hot water circulation circuit, and then circulated and supplied to each hot water supply destination, so that the heating of hot water by the heat source unit can be leveled out and the capacity of the heat source unit can be reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-148316 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-205698 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in sealed hot water supply systems, generally no hot water storage tank is installed or only a relatively small sealed hot water storage tank is installed, so if the heating capacity of the heat source unit is set to a large value in anticipation of a peak period when the hot water supply load is high lasting for a relatively long time or when the hot water supply load during that peak period is very high, this can result in problems such as a decrease in thermal efficiency and increased costs. On the other hand, in open-type hot water supply systems, an open-type hot water storage tank with a relatively large hot water storage capacity that can accommodate all hot water supply loads is generally installed, so securing installation space and fitting can sometimes be an issue.

[0005] In light of this situation, the main objective of the present invention is to provide a technology that improves energy efficiency in a hot water supply system equipped with a hot water circulation circuit that circulates hot water between a heat source unit and each hot water supply destination, by balancing the hot water storage capacity of the hot water storage tank and the heating capacity of the heat source unit, thereby making it easy to secure installation space and fit. [Means for solving the problem]

[0006] The first characteristic configuration of the present invention is a hot water supply system equipped with a hot water circulation circuit that circulates hot water between a heat source unit and each hot water supply destination, The hot water supply system includes an open-type hot water storage tank capable of storing hot water heated by the heat source unit, and a hot water supply mode switching means capable of switching the hot water supply mode by changing the state of the hot water circulation circuit, The hot water supply mode includes a closed hot water supply mode and an open hot water supply mode, The closed hot water supply mode is a hot water supply mode in which the state of the hot water circulation circuit is in a closed state separated from the hot water storage tank, and the hot water heated by the heat source unit is circulated and supplied to each of the hot water supply destinations by operating a circulation pump provided in the hot water circulation circuit, The open-type hot water supply mode is a hot water supply mode in which the hot water circulation circuit is in an open state connected to the hot water storage tank, and the hot water heated by the heat source unit is temporarily stored in the hot water storage tank by operating a pressure pump provided in the hot water circulation circuit, and then circulated and supplied to each of the hot water supply destinations.

[0007] According to this configuration, the open-type hot water storage tank is configured to be connectable and disconnectable from the hot water circulation circuit, and a circulation pump and a pressure pump are provided in the hot water circulation circuit, and hot water supply mode switching means is provided. The hot water supply mode switching means can switch the hot water supply mode between a closed-type hot water supply mode and an open-type hot water supply mode by changing the connection state of the hot water storage tank and the operating states of the circulation pump and pressure pump as the state of the hot water circulation circuit. When the hot water supply mode is switched to the sealed hot water supply mode by the hot water supply mode switching means, the hot water heated in the heat source unit is circulated and supplied to each hot water supply destination by the operation of the circulation pump through a sealed hot water circulation circuit, so the hot water transport power of the circulation pump only needs to cover the pressure loss in the hot water circulation circuit, reducing the transport power and improving energy saving. On the other hand, if the hot water supply mode is switched to the open hot water supply mode using the hot water supply mode switching means, the hot water heated by the heat source unit is temporarily stored in the hot water storage tank by operating a pressure pump installed in the open hot water circulation circuit, and then circulated and supplied to each hot water supply destination.This means that the heating of hot water by the heat source unit is leveled out, thereby suppressing the capacity of the heat source unit, and it is possible to respond to relatively large hot water supply loads during peak times. Therefore, the present invention provides a technology that improves energy efficiency while facilitating the securing of installation space and fitting by balancing the hot water storage capacity of the hot water storage tank and the heating capacity of the heat source in a hot water supply system equipped with a hot water circulation circuit that circulates hot water between a heat source unit and each hot water supply destination.

[0008] A second characteristic configuration of the present invention is that it is equipped with a hot water supply mode control means that controls the operation of the hot water supply mode switching means based on the hot water supply load at each hot water supply destination, and automatically switches the hot water supply mode between the closed type hot water supply mode and the open type hot water supply mode.

[0009] According to this configuration, the hot water supply mode control means can automatically switch the hot water supply mode between the closed-type hot water supply mode and the open-type hot water supply mode based on the hot water supply load. That is, during normal times when the hot water supply load is relatively small, the hot water supply mode control means automatically switches the hot water supply mode to the closed-type hot water supply mode. This allows for operation that emphasizes energy conservation. On the other hand, during peak times when the hot water supply load is relatively large, the hot water supply mode control means automatically switches the hot water supply mode to the open-type hot water supply mode. This allows for the hot water heated by the heat source unit to be stored in the hot water storage tank in advance, making it possible to respond to the large hot water supply load, while leveling out the heating of the hot water by the heat source unit and suppressing the capacity of the heat source unit.

[0010] A third characteristic configuration of the present invention is that the hot water circulation circuit has a pressure pump bypass line that bypasses the pressure pump in the closed type hot water supply mode to allow hot water to flow and is provided with a check valve that prevents backflow of hot water in the open type hot water supply mode, and a circulation pump bypass line that bypasses the circulation pump in the open type hot water supply mode to allow hot water to flow and is provided with a check valve that prevents backflow of hot water in the closed type hot water supply mode, The hot water supply mode switching means switches the hot water supply mode between the closed type hot water supply mode and the open type hot water supply mode, and sets the circulation pump and the pressurizing pump to a simultaneous pump operation state.

[0011] According to this configuration, a pressure pump bypass line and a circulation pump bypass line, each equipped with a check valve, are provided in the hot water circulation circuit, and when the hot water mode is switched between a closed-type hot water supply mode and an open-type hot water supply mode, the circulation pump and the pressure pump are operated simultaneously at the transition timing between the hot water mode before the switch and the hot water mode after the switch. This reliably prevents the circulation pump and the pressure pump from momentarily stopping at the same time or the start of operation of one pump and the stop of operation of the other pump at the transition timing, thereby reliably suppressing pressure fluctuations in the pipes in the hot water circulation circuit due to these conditions.

[0012] A fourth characteristic configuration of the present invention is that the hot water circulation circuit has a hot water storage tank bypass pipe line provided with a hot water storage tank bypass valve that bypasses the hot water storage tank in the closed type hot water supply mode to allow hot water to flow and stops the flow of hot water in the open type hot water supply mode, and a hot water storage tank inlet / outlet pipe line provided with a hot water storage tank inlet / outlet valve that allows hot water to flow in and out of the hot water storage tank in the open type hot water supply mode and is closed in the closed type hot water supply mode to stop the flow of hot water in and out of the hot water storage tank, The hot water supply mode switching means is characterized in that when switching the hot water supply mode between the open type hot water supply mode and the closed type hot water supply mode, it places the hot water storage tank inlet / outlet valve and the hot water storage tank bypass valve in a simultaneous pipe opening state.

[0013] According to this configuration, a hot water circulation circuit is provided with a hot water storage tank bypass line provided with a hot water storage tank bypass valve and a hot water storage tank inlet / outlet line provided with a hot water storage tank inlet / outlet valve, and when the hot water supply mode is switched between a closed-type hot water supply mode and an open-type hot water supply mode, the hot water storage tank inlet / outlet valve and the hot water storage tank bypass valve are simultaneously opened at the transition timing between the hot water supply mode before the switch and the hot water supply mode after the switch, thereby reliably preventing the hot water storage tank inlet / outlet valve and the hot water storage tank bypass valve from momentarily closing simultaneously or from opening on one side and closing on the other side at the transition timing, thereby reliably suppressing pressure fluctuations in the pipes in the hot water circulation circuit due to these conditions. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a hot water supply system according to an embodiment of the present invention and a state in a closed hot water supply mode. [Figure 2] FIG. 1 is a diagram showing a schematic configuration of a hot water supply system according to an embodiment of the present invention and a state in an open-type hot water supply mode. [Figure 3] A diagram showing the state of the first transition timing in the closed hot water supply mode transition process [Figure 4]FIG. 10 is a diagram showing the state of the second transition timing in the closed hot water supply mode transition process. [Figure 5] FIG. 10 is a diagram showing the state of the first transition timing in the open-type hot water supply mode transition process. [Figure 6] A diagram showing the state of the second transition timing in the open-type hot water supply mode transition process [Figure 7] Diagram showing the processing flow for hot water supply mode control DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the hot water supply system according to the present invention will be described with reference to the drawings. In Figures 1 to 6, open valves are shown in white, closed valves are shown in black, pipes through which hot water flows and pumps in operation are shown in solid lines, and pipes through which hot water does not flow and pumps that are stopped are shown in dashed lines.

[0016] As shown in Figures 1 and 2, the hot water supply system of this embodiment (hereinafter referred to as "this system") is configured to include a hot water circulation circuit 10 that circulates hot water between a heat source unit 1 such as a boiler and each hot water supply destination 2 such as a hot water tap, a hot water heating appliance, or a bathtub. The hot water supply system is also provided with a control device 60 for controlling the operation of various devices, and this control device 60 functions as a hot water supply load acquisition means 61, a hot water supply mode switching means 62, a hot water supply mode control means 63, etc., which will be described later, by executing a predetermined computer program. This system is provided with an open-type hot water storage tank 40 capable of storing hot water heated by the heat source unit 1, and a hot water supply mode switching means 62 capable of switching the hot water supply mode by changing the state of the hot water circulation circuit 10.A configuration is adopted that balances the hot water storage capacity of the hot water storage tank 40 and the heating capacity of the heat source unit 1, making it easy to secure installation space and fit, while improving energy conservation, and the details of this configuration are described below.

[0017] The hot water circulation circuit 10 has an outgoing pipe 11 that supplies hot water heated by the heat source 1 to each hot water supply destination 2, and a return pipe 12 that returns the hot water that has passed through each hot water supply destination 2 to the heat source 1. On the outgoing pipe 11 side, there is an open-type hot water storage tank 40 that can store the hot water heated by the heat source 1, and a plurality of pressure pumps 30 connected in parallel. On the return pipe 12 side, there are a plurality of circulation pumps 20 connected in parallel. The hot water circulation circuit 10 also has a pressure relief valve 15 to alleviate excessive pressure increases and a pressure tank 16 to alleviate sudden pressure fluctuations. The specific configuration will be described later, but the open-type hot water storage tank 40 is configured to be connectable to and disconnectable from the hot water circulation circuit 10. With this configuration, the state of the hot water circulation circuit 10 can be switched between a sealed state (state shown in FIG. 1) in which it is disconnected from the hot water storage tank 40, and an open state (state shown in FIG. 2) in which it is connected to the hot water storage tank 40. Furthermore, the circulation pump 20 and the pressure pump 30 are configured to be able to circulate hot water through the hot water circulation circuit 10 by operating one or both of them. The hot water supply mode switching means 62 is configured to be able to switch the hot water supply mode between a closed type hot water supply mode (see Figure 1) and an open type hot water supply mode (see Figure 2) described below by changing the connection state of the hot water storage tank 40 and the operating state of the circulation pump 20 and the pressure pump 30 as the state of the hot water circulation circuit 10.

[0018] That is, in the sealed hot water supply mode, as shown in Fig. 1, the hot water circulation circuit 10 is in the sealed state, and the hot water heated by the heat source unit 1 is circulated to each hot water supply destination 2 by the operation of the circulation pump 20 provided in the hot water circulation circuit 10 without being stored in the hot water storage tank 40. When the hot water supply mode becomes the sealed hot water supply mode, the hot water transport power of the circulation pump 20 only needs to cover the pressure loss in the hot water circulation circuit 10, so the transport power is reduced and energy conservation is improved.

[0019] On the other hand, in the open-type hot water supply mode, as shown in Fig. 2, the state of the hot water circulation circuit 10 is set to the open state, and the hot water heated by the heat source unit 1 is temporarily stored in the hot water storage tank 40 by operation of the pressure pump 30 provided in the hot water circulation circuit 10, and is circulated and supplied to each hot water supply destination 2. When the hot water supply mode is set to the open-type hot water supply mode, the heating of the hot water by the heat source unit 1 is leveled out, and the capacity of the heat source unit 1 is suppressed, while it is possible to respond to a relatively large hot water supply load during peak times.

[0020] Next, a specific configuration for switching the hot water supply mode by the hot water supply mode switching means 62 will be described. 1 and 2, on the outgoing pipe 11 side of the hot water circulation circuit 10, there are provided a hot water storage tank inlet pipe 45 and a hot water storage tank outlet pipe 48, which are hot water storage tank inlet and outlet pipes for inflow and outflow of hot water to and from the hot water storage tank 40, and a hot water storage tank bypass pipe 42 for bypassing the hot water storage tank 40 to allow the hot water to flow. Furthermore, the hot water storage tank inlet pipe 45 and the hot water storage tank outlet pipe 48 are provided with a hot water storage tank inlet valve 46 and a hot water storage tank outlet valve 49, which serve as hot water storage tank inlet and outlet valves that can stop the flow of hot water. Meanwhile, the hot water storage tank bypass pipe 42 is provided with a hot water storage tank bypass valve 43 that can stop the flow of hot water.

[0021] On the outgoing pipe 11 side of the hot water circulation circuit 10, a pressure pump bypass pipe 32 is provided in parallel with the pressure pump 30, which bypasses the pressure pump 30 to allow hot water to flow in the above-mentioned closed type hot water supply mode (see Figure 1) and is equipped with a backflow prevention valve 33 to prevent backflow of hot water in the above-mentioned open type hot water supply mode (see Figure 2). On the other hand, on the return line 12 side of the hot water circulation circuit 10, a circulation pump bypass line 22 is arranged in parallel to the circulation pump 20, which bypasses the circulation pump 20 to allow hot water to flow in the above-mentioned open hot water supply mode (see Figure 2) and is equipped with a backflow prevention valve 23 to prevent hot water from flowing back in the closed hot water supply mode (see Figure 1).

[0022] That is, in the sealed hot water supply mode shown in Figure 1, the hot water supply mode switching means 62 closes the hot water storage tank inlet valve 46 and the hot water storage tank outlet valve 49, opens the hot water storage tank bypass valve 43, operates the circulation pump 20, and stops the pressure pump 30. Then, in the outgoing pipe 11 of the hot water circulation circuit 10 in the closed hot water supply mode, the hot water heated in the heat source 1 passes through the hot water storage tank bypass pipe 42 without being stored in the hot water storage tank 40, and passes through the pressure pump bypass pipe 32 in which the check valve 33 is open without passing through the pressure pump 30, and is supplied to each hot water supply destination 2. Also, in the return pipe 12 of the hot water circulation circuit 10 in the closed hot water supply mode, the hot water that has passed through each hot water supply destination 2 passes through the operating circulation pump 20, and is returned to the heat source 1, without passing through the circulation pump bypass pipe 22 in which the check valve 23 is closed.

[0023] On the other hand, in the open-type hot water supply mode shown in Figure 2, the hot water supply mode switching means 62 opens the hot water storage tank inlet valve 46 and the hot water storage tank outlet valve 49, closes the hot water storage tank bypass valve 43, stops the circulation pump 20, and operates the pressure pump 30. Then, in the outgoing pipe 11 of the hot water circulation circuit 10 in the open-type hot water supply mode, the hot water heated in the heat source unit 1 is temporarily stored in the hot water storage tank 40 without passing through the hot water storage tank bypass pipe 42, and passes through the operating pressure pump 30 without passing through the pressure pump bypass pipe 32 in which the check valve 33 is closed, and is supplied to each hot water supply destination 2. Also, in the return pipe 12 of the hot water circulation circuit 10 in the open-type hot water supply mode, the hot water that has passed through each hot water supply destination 2 passes through the circulation pump bypass pipe 22 in which the check valve 23 is open, and is returned to the heat source unit 1 without passing through the stopped circulation pump 20. In addition, in the open-type hot water supply mode, the amount of hot water flowing in and out of the hot water storage tank 40 through the hot water storage tank inlet pipe 45 and the hot water storage tank outlet pipe 48 is adjusted so that the water level in the hot water storage tank 40 detected by the water level sensor 41 is maintained at the desired water level.

[0024] [Hot water supply mode control] Next, the hot water supply mode control will be described. This system is provided with a hot water supply load acquisition means 61 and a hot water supply mode control means 63 for automatically switching the hot water supply mode by the hot water supply mode switching means 62 as described above.

[0025] The hot water load acquisition means 61 is a means for acquiring the hot water load of each hot water destination 2. Note that various known methods can be used to acquire the hot water load, but for example, the amount of heat consumed in each hot water destination 2 can be calculated by multiplying the temperature difference between the temperature of the hot water supplied to each hot water destination 2 through the outgoing pipe 11 in the hot water circulation circuit 10 and the temperature of the hot water returning to the heat source unit 1 through the return pipe 12 by the flow rate of these hot water, and this amount of heat consumption can be acquired as the hot water load. Furthermore, the hot water supply load acquisition means 61 does not directly obtain the hot water supply load, but can predict the hot water supply load of each hot water supply destination 2 from other information related to the heat consumption state in each hot water supply destination 2. For example, if the facility in which this system is installed is an accommodation facility such as a hotel with multiple guest rooms that serve as hot water supply destinations 2, the hot water supply load in each guest room can be predicted based on the operating status and reservation status of each guest room.

[0026] Then, the hot water supply mode control means 63 controls the operation of the hot water supply mode switching means 62 based on the hot water supply load at each hot water supply destination 2 acquired by the hot water supply load acquisition means 61, and automatically switches the hot water supply mode between the above-mentioned closed hot water supply mode (see Figure 1) and open hot water supply mode (see Figure 2). That is, also referring to the flow diagram shown in Fig. 7, first, a hot water load determination process (step #1 in Fig. 7) is performed in which the hot water load at each hot water supply destination 2 acquired by the hot water load acquisition means 61 is referenced to determine whether or not it is peak time. In this hot water load determination process, if the hot water load at each hot water supply destination 2 is relatively small, it is determined to be normal time (No in step #1 in Fig. 7), and if the hot water load at each hot water supply destination 2 is relatively large, it is determined to be peak time (Yes in step #1 in Fig. 7). In this embodiment, if the hot water load itself acquired by the hot water load acquisition means 61 or its moving average value is below a predetermined set value, it is determined to be normal time (No in step #1 in Fig. 7), and if the hot water load itself acquired by the hot water load acquisition means 61 or its moving average value is equal to or greater than a predetermined set value, it is determined to be peak time (Yes in step #1 in Fig. 7). Although such a determination may be made at any time, by making it at regular intervals, such as when weekdays change to holidays, or when a lodging facility changes from off-season to busy season, excessively frequent switching of the hot water supply mode can be avoided.

[0027] Then, during normal operation (No in step #1 in FIG. 7), if the current hot water supply mode is the open-type hot water supply mode (see FIG. 2) and not the closed-type hot water supply mode (see FIG. 1) (No in step #10 in FIG. 7), the closed-type hot water supply mode transition process (step #11 in FIG. 7) described below is executed by hot water supply mode switching means 62, and the hot water supply mode is switched from the open-type hot water supply mode (see FIG. 2) to the closed-type hot water supply mode (see FIG. 1) (step #17 in FIG. 7). Also, during normal operation (No in step #1 in FIG. 7), if the current hot water supply mode is the closed-type hot water supply mode (see FIG. 1) (Yes in step #10 in FIG. 7), the hot water supply mode is maintained in the same closed-type hot water supply mode (see FIG. 1) as the current mode (step #17 in FIG. 7). In this way, during normal times when the hot water supply load is relatively small, the hot water supply mode control means 63 automatically switches the hot water supply mode to the closed hot water supply mode (see FIG. 1), thereby realizing operation that places importance on energy conservation.

[0028] On the other hand, during peak times (Yes in step #1 in FIG. 7), if the current hot water supply mode is the closed-type hot water supply mode (see FIG. 1) and not the open-type hot water supply mode (see FIG. 2) (No in step #20 in FIG. 7), the hot water supply mode switching means 62 executes the open-type hot water supply mode transition process (step #21 in FIG. 7) described below, thereby switching the hot water supply mode from the closed-type hot water supply mode (see FIG. 1) to the open-type hot water supply mode (see FIG. 2) (step #27 in FIG. 7). Also, during peak times (Yes in step #1 in FIG. 7), if the current hot water supply mode is the open-type hot water supply mode (see FIG. 2) (Yes in step #20 in FIG. 7), the hot water supply mode is maintained in the same open-type hot water supply mode (see FIG. 2) as the current mode (step #27 in FIG. 7). In this way, during peak times when the hot water supply load is relatively large, the hot water supply mode control means 63 automatically switches the hot water supply mode to the open-type hot water supply mode (see Figure 2), so that the large hot water supply load can be handled by storing hot water heated by the heat source unit 1 in advance in the hot water storage tank 40, and the heating of hot water by the heat source unit 1 is leveled out, thereby suppressing the capacity of the heat source unit 1.

[0029] Next, the details of the closed type hot water supply mode transition process (step #11 in FIG. 7) and the open type hot water supply mode transition process (step #21 in FIG. 7) will be described.

[0030] (Transition process to sealed hot water supply mode) In the closed hot water supply mode transition process (step #11 in Figure 7) performed to switch the hot water supply mode from the open hot water supply mode (see Figure 2) to the closed hot water supply mode (see Figure 1), a simultaneous pump operation state is initiated (step #12 in Figure 7) to operate the circulation pump 20 and the pressure pump 30, followed by a simultaneous pipeline opening state to open the hot water storage tank inlet valve 46, the hot water storage tank outlet valve 49, and the hot water storage tank bypass valve 43 (step #14 in Figure 7), followed by both the simultaneous pump operation state and the simultaneous pipeline opening state ending (step #16 in Figure 7).

[0031] That is, in the closed-type hot water supply mode transition process (step #11 in FIG. 7), at the first transition timing (step #13 in FIG. 7) from when the simultaneous pump operation state starts (step #12 in FIG. 7) to when the simultaneous pipe open state starts (step #14 in FIG. 7), as shown in FIG. 3, the circulation pump 20 starts operating in addition to the pressure pump 30 that was operating in the open-type hot water supply mode before the transition (see FIG. 2), thereby entering a simultaneous pump operation state in which the circulation pump 20 and the pressure pump 30 are operated simultaneously. Then, at this first transition timing (step #13 in FIG. 7), the hot water heated by the heat source 1 is temporarily stored in the hot water storage tank 40 without passing through the hot water storage tank bypass pipe 42, passes through the operating pressure pump 30, and is supplied to each hot water supply destination 2, and the hot water that has passed through each hot water supply destination 2 passes through the operating circulation pump 20 and is returned to the heat source 1.

[0032] At this time, at the first transition timing (step #13 in FIG. 7), in order to minimize fluctuations in the pressure inside the hot water circulation circuit 10, the water supply rate of the circulation pump 20, which starts operating, is gradually increased until it reaches the set water supply rate that is set in the post-transition sealed hot water supply mode (see FIG. 1). Therefore, in the initial stage of the first transition timing, the water supply rate of the circulation pump 20 is smaller than the water supply rate of the pressure pump 30 that was already operating, and hot water flows through the circulation pump bypass line 22 that bypasses the circulation pump 20. Then, when the water supply rate of the circulation pump 20 is increased and exceeds the water supply rate of the pressure pump 30 that was already operating, the flow of hot water through the circulation pump bypass line 22 stops, and hot water flows through the pressure pump bypass line 32 that bypasses the pressure pump 30, as shown in FIG. 4.

[0033] Furthermore, in the closed hot water supply mode transition process (step #11 in Figure 7), at the second transition timing (step #15 in Figure 7) from when the simultaneous pipe opening state begins (step #14 in Figure 7) to when both the simultaneous pump operation state and the simultaneous pipe opening state end (step #16 in Figure 7), as shown in Figure 4, the simultaneous pump operation state is maintained, and in addition to the hot water storage tank inlet valve 46 and the hot water storage tank outflow valve 49 that were open in the open hot water supply mode before the transition (see Figure 2), the hot water storage tank bypass valve 43 is opened, resulting in a simultaneous pipe opening state in which the hot water storage tank inlet valve 46, the hot water storage tank outflow valve 49, and the hot water storage tank bypass valve 43 are opened simultaneously. Then, at this second transition timing (step #15 in Figure 7), the hot water heated in the heat source unit 1 is distributed and passes through both the hot water storage tank 40 and the hot water storage tank bypass pipe 42, passes through the operating pressure pump 30, and is supplied to each hot water supply destination 2, and at the same time, the hot water that has passed through each hot water supply destination 2 passes through the operating circulation pump 20 and is returned to the heat source unit 1.

[0034] Then, after the second transition timing (step #15 in Figure 7), the operation of the pressure pump 30 is stopped and the hot water tank inlet valve 46 and the hot water tank outlet valve 49 are closed, thereby ending both the pump simultaneous operation state and the pipeline simultaneous opening state (step #16 in Figure 7). At this time, the timing for closing the hot water storage tank inlet valve 46 and the hot water storage tank outlet valve 49 may be the same, but by closing the hot water storage tank outlet valve 49 later than the hot water storage tank inlet valve 46, it is possible to prevent overflows and the like caused by an excessive rise in the water level in the hot water storage tank 40. Also, the pressure pump 30 may be stopped instantly, but by gradually reducing the amount of water delivered by the pressure pump 30 and then stopping it, it is possible to suppress pressure fluctuations within the pipes in the hot water circulation circuit 10.

[0035] In this way, by setting the pumps to the simultaneous operation state as described above at the first transition timing (step #13 in Figure 7, see Figure 3) and the second transition timing (step #15 in Figure 7, see Figure 4) when the closed hot water supply mode transition process (step #11 in Figure 7) is executed to switch the hot water supply mode from the open hot water supply mode (see Figure 2) to the closed hot water supply mode (see Figure 1), it is possible to reliably avoid a situation in which the circulation pump 20 and the pressure pump 30 suddenly stop at the same time or a situation in which one side starts operating and the other side stops operating at the same time, thereby reliably suppressing pressure fluctuations in the pipes in the hot water circulation circuit 10 caused by these situations. Furthermore, at the second transition timing (step #15 in Figure 7, see Figure 4) when the closed hot water supply mode transition process (step #11 in Figure 7) is executed to switch the hot water supply mode from the open hot water supply mode (see Figure 2) to the closed hot water supply mode (see Figure 1), the above-mentioned simultaneous pipe opening state is achieved, which reliably avoids a state in which the hot water storage tank inlet valve 46, the hot water storage tank outlet valve 49, and the hot water storage tank bypass valve 43 are instantly closed at the same time, or a state in which one side is opened and the other side is closed simultaneously, thereby reliably suppressing pressure fluctuations in the pipes in the hot water circulation circuit 10 caused by these states. Furthermore, since the simultaneous pump operation state is initiated at the first transition timing (step #13 in Figure 7, see Figure 3) prior to the simultaneous pipeline opening state which is initiated at the second transition timing (step #15 in Figure 7, see Figure 4), the switching of the operation target from the pressure pump 30 to the circulation pump 20 is carried out stably.

[0036] (Open-type hot water supply mode transition process) In the open-type hot water supply mode transition process (step #21 in Figure 7) performed to switch the hot water supply mode from the closed-type hot water supply mode (see Figure 1) to the open-type hot water supply mode (see Figure 2), a simultaneous pump operation state is initiated (step #22 in Figure 7) to operate the circulation pump 20 and the pressure pump 30, followed by a simultaneous pipeline opening state to open the hot water storage tank inlet valve 46, the hot water storage tank outlet valve 49, and the hot water storage tank bypass valve 43 (step #24 in Figure 7), followed by both the simultaneous pump operation state and the simultaneous pipeline opening state ending (step #26 in Figure 7).

[0037] That is, in the open-type hot water supply mode transition process (step #21 in FIG. 7), at the first transition timing (step #23 in FIG. 7) from when the simultaneous pump operation state starts (step #22 in FIG. 7) to when the simultaneous open-type pipe state starts (step #24 in FIG. 7), as shown in FIG. 5, the pressurization pump 30 starts operating in addition to the circulation pump 20 that was operating in the closed-type hot water supply mode before the transition (see FIG. 1), thereby entering a simultaneous pump operation state in which the circulation pump 20 and the pressurization pump 30 are operated simultaneously. Then, at this first transition timing (step #23 in FIG. 7), the hot water heated in the heat source unit 1 passes through the hot water storage tank bypass pipe 42 without being stored in the hot water storage tank 40, passes through the operating pressurization pump 30, and is supplied to each hot water supply destination 2, and the hot water that has passed through each hot water supply destination 2 passes through the operating circulation pump 20 and is returned to the heat source unit 1.

[0038] At this time, at the first transition timing (step #23 in FIG. 7), in order to minimize fluctuations in the pressure inside the hot water circulation circuit 10, the water supply rate of the pressure pump 30, which starts operating, is gradually increased until it reaches the set water supply rate that is set in the open-type hot water supply mode (see FIG. 2) after the transition. Therefore, in the initial stage of the first transition timing, the water supply rate of the pressure pump 30 is smaller than the water supply rate of the circulation pump 20 that was already operating, and hot water flows through the pressure pump bypass pipe 32 that bypasses the pressure pump 30. Then, when the water supply rate of the pressure pump 30 is increased and exceeds the water supply rate of the circulation pump 20 that was already operating, the flow of hot water through the pressure pump bypass pipe 32 stops, and hot water flows through the circulation pump bypass pipe 22 that bypasses the circulation pump 20, as shown in FIG. 6.

[0039] Furthermore, in the open-type hot water supply mode transition process (step #21 in Figure 7), at the second transition timing (step #25 in Figure 7) from when the simultaneous pipe opening state begins (step #24 in Figure 7) to when both the simultaneous pump operation state and the simultaneous pipe opening state end (step #26 in Figure 7), as shown in Figure 6, the simultaneous pump operation state is maintained, and in addition to the hot water storage tank bypass valve 43 which was open in the closed-type hot water supply mode before the transition (see Figure 1), the hot water storage tank inlet valve 46 and the hot water storage tank outlet valve 49 are opened, resulting in a simultaneous pipe opening state in which the hot water storage tank inlet valve 46, the hot water storage tank outlet valve 49, and the hot water storage tank bypass valve 43 are opened simultaneously. Then, at this second transition timing (step #25 in Figure 7), the hot water heated in the heat source unit 1 is distributed and passes through both the hot water storage tank 40 and the hot water storage tank bypass pipe 42, passes through the operating pressure pump 30, and is supplied to each hot water supply destination 2, and at the same time, the hot water that has passed through each hot water supply destination 2 passes through the operating circulation pump 20 and is returned to the heat source unit 1. At this time, the timing for opening the hot water storage tank inlet valve 46 and the hot water storage tank outlet valve 49 may be the same, but by opening the hot water storage tank outlet valve 49 earlier than the hot water storage tank inlet valve 46, overflows and other problems caused by excessive rises in the water level in the hot water storage tank 40 can be prevented.

[0040] Then, after the second transition timing (step #25 in Figure 7), the operation of the circulation pump 20 is stopped and the hot water tank bypass valve 43 is closed, thereby ending both the pump simultaneous operation state and the pipeline simultaneous opening state (step #26 in Figure 7). At this time, the circulation pump 20 may be stopped instantly, but by gradually reducing the amount of water sent by the circulation pump 20 before stopping it, pressure fluctuations within the pipes in the hot and cold water circulation circuit 10 can be suppressed.

[0041] In this way, by setting the pumps to the simultaneous operation state as described above at the first transition timing (step #23 in Figure 7, see Figure 5) and the second transition timing (step #25 in Figure 7, see Figure 6) when the open-type hot water supply mode transition process (step #21 in Figure 7) is executed to switch the hot water supply mode from the closed-type hot water supply mode (see Figure 1) to the open-type hot water supply mode (see Figure 2), it is possible to reliably avoid a situation in which the circulation pump 20 and the pressure pump 30 suddenly stop at the same time or a situation in which one side starts operating and the other side stops operating at the same time, thereby reliably suppressing pressure fluctuations in the pipes in the hot water circulation circuit 10 caused by these situations. Furthermore, at the second transition timing (step #25 in Figure 7, see Figure 6) when the open-type hot water supply mode transition process (step #21 in Figure 7) is executed to switch the hot water supply mode from the closed-type hot water supply mode (see Figure 1) to the open-type hot water supply mode (see Figure 2), the above-mentioned simultaneous pipe opening state is achieved, which reliably avoids a state in which the hot water storage tank inlet valve 46, the hot water storage tank outlet valve 49, and the hot water storage tank bypass valve 43 are instantly closed at the same time, or a state in which one side is opened and the other side is closed simultaneously, thereby reliably suppressing pressure fluctuations in the pipes in the hot water circulation circuit 10 caused by these states. Furthermore, since the simultaneous pump operation state is initiated at the first transition timing (step #23 in Figure 7, see Figure 5) prior to the simultaneous pipeline opening state which is initiated at the second transition timing (step #25 in Figure 7, see Figure 6), the switching of the operation target from the circulation pump 20 to the pressure pump 30 is carried out stably.

[0042] [Another embodiment] Other embodiments of the present invention will be described below. Note that the configurations of the embodiments described below are not limited to being applied independently, but can also be applied in combination with the configurations of other embodiments.

[0043] (1) In the above embodiment, a hot water supply mode control means 63 is provided that controls the operation of the hot water supply mode switching means 62 based on the hot water supply load at each hot water supply destination 2 to automatically switch the hot water supply mode between a closed type hot water supply mode and an open type hot water supply mode. However, such hot water supply mode control means 63 may be omitted, and the hot water supply mode may be switched manually by the user, for example.

[0044] (2) In the above embodiment, when the closed-type hot water supply mode transition process (step #11 in Figure 7) or the open-type hot water supply mode transition process (step #21 in Figure 7) is executed to switch the hot water supply mode between the closed-type hot water supply mode and the open-type hot water supply mode, a simultaneous pump operation state is set in which the circulation pump 20 and the pressure pump 30 are operated, and a simultaneous pipeline open state is set in which the hot water storage tank inlet valve 46, the hot water storage tank outlet valve 49, and the hot water storage tank bypass valve 43 are opened. However, one or both of these simultaneous pump operation states and simultaneous pipeline open states may be omitted, such as by simultaneously starting operation of one of the circulation pump 20 and the pressure pump 30 and stopping operation of the other, or by simultaneously closing one of the hot water storage tank inlet valve 46, the hot water storage tank outlet valve 49, and the hot water storage tank bypass valve 43 and opening the other. [Explanation of symbols]

[0045] 1 Heat source 2 Hot water supply destination 10 Hot water circulation circuit 20 Circulation Pump 22 Circulation pump bypass line 23 Check valve 30 Pressure pump 32 Pressure pump bypass line 33 Check valve 40 Hot water tank 42 Hot water tank bypass line 43 Hot water tank bypass valve 45 Hot water tank inlet pipe (hot water tank inlet / outlet pipe) 46 Hot water tank inlet valve (hot water tank inlet / outlet valve) 48 Hot water tank outflow pipe (hot water tank inflow and outflow pipe) 49 Hot water tank outflow valve (hot water tank inflow / outflow valve) 62 Hot water supply mode switching means 63 Hot water supply mode control means

Claims

1. A hot water supply system equipped with a hot water circulation circuit that circulates hot water between a heat source unit and each hot water supply destination, The hot water supply system includes an open-type hot water storage tank capable of storing hot water heated by the heat source unit, and a hot water supply mode switching means capable of switching the hot water supply mode by changing the state of the hot water circulation circuit, The hot water supply mode includes a closed hot water supply mode and an open hot water supply mode, The closed hot water supply mode is a hot water supply mode in which the state of the hot water circulation circuit is in a closed state separated from the hot water storage tank, and the hot water heated by the heat source unit is circulated and supplied to each of the hot water supply destinations by operating a circulation pump provided in the hot water circulation circuit, The open-type hot water supply mode is a hot water supply mode in which the hot water circulation circuit is in an open state connected to the hot water storage tank, and the hot water heated by the heat source unit is temporarily stored in the hot water storage tank by operating a pressure pump provided in the hot water circulation circuit, and then circulated and supplied to each of the hot water supply destinations.

2. The hot water supply system of claim 1, further comprising a hot water supply mode control means for controlling the operation of the hot water supply mode switching means based on the hot water supply load at each hot water supply destination, thereby automatically switching the hot water supply mode between the closed type hot water supply mode and the open type hot water supply mode.

3. The hot water circulation circuit has a pressure pump bypass line that bypasses the pressure pump in the closed hot water supply mode to allow hot water to flow and is provided with a check valve that prevents backflow of hot water in the open hot water supply mode, and a circulation pump bypass line that bypasses the circulation pump in the open hot water supply mode to allow hot water to flow and is provided with a check valve that prevents backflow of hot water in the closed hot water supply mode, The hot water supply system according to claim 1 or 2, wherein the hot water supply mode switching means switches the hot water supply mode between the closed-type hot water supply mode and the open-type hot water supply mode, and activates the circulation pump and the pressure pump in a simultaneous pump operation state.

4. The hot water circulation circuit has a hot water storage tank bypass pipe line provided with a hot water storage tank bypass valve that bypasses the hot water storage tank in the closed type hot water supply mode to allow hot water to flow and stops the flow of hot water in the open type hot water supply mode, and a hot water storage tank inlet / outlet pipe line provided with a hot water storage tank inlet / outlet valve that allows hot water to flow in and out of the hot water storage tank in the open type hot water supply mode and is closed in the closed type hot water supply mode to stop the flow of hot water in and out of the hot water storage tank, A hot water supply system as described in claim 1 or 2, wherein the hot water supply mode switching means, when switching the hot water supply mode between the open type hot water supply mode and the closed type hot water supply mode, places the hot water storage tank inlet / outlet valve and the hot water storage tank bypass valve in a simultaneous pipe open state.

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