Hot water supply equipment

Abstract

A water heater capable of increasing the amount of high-temperature water supplied to a hot water supply target. The hot water supply flow path (40) is configured to perform a first hot water supply operation in which, in a hot water storage state in which a low temperature layer (L), a medium temperature layer (M), and a high temperature layer (H) are formed inside the tank (30), water in the medium temperature layer (M) is heated to a first temperature by the heating section (13) and supplied to a hot water supply target (T).

Description

[Technical field]

[0001] The present disclosure relates to a water heating apparatus. [Background technology]

[0002] The water heater in Patent Document 1 includes a heat exchanger (heating unit) and a tank that stores water heated by the heat exchanger. Patent Document 1 describes a hot water supply flow path that heats water in the lower part of the tank with the heat exchanger and then supplies the heated water to a specified hot water supply target (bath, shower, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3925433 Summary of the Invention [Problem to be solved by the invention]

[0004] In a hot water supply device such as that described in Patent Document 1, it is possible to imagine an operation in which low-temperature water at the bottom of a tank is heated to a high temperature in a heating section and supplied to a target for hot water supply. In this operation, there is a large temperature difference between the water flowing into the heating section and the water flowing out of the heating section. In order to heat low-temperature water to a high temperature in the heating section, it is necessary to reduce the flow rate of water flowing through the heating section. As a result, there is a problem in that when a large amount of high-temperature water is demanded by the target for hot water supply, a sufficient amount of high-temperature water to meet this demand cannot be supplied to the target for hot water supply.

[0005] An object of the present disclosure is to provide a water heating device that can increase the amount of high-temperature water supplied to a target for hot water supply. [Means for solving the problem]

[0006] The first aspect is a hot water supply device equipped with a hot water supply flow path (40) having a heating section (13) that heats water and a tank (30) that stores the water heated by the heating section (13), characterized in that the hot water supply flow path (40) is configured to execute a first hot water supply operation in which, in a hot water storage state in which a low temperature layer (L), a medium temperature layer (M), and a high temperature layer (H) are formed inside the tank (30), water in the medium temperature layer (M) is heated to a first temperature by the heating section (13) and supplied to a hot water supply target (T).

[0007] In the first mode, in the first hot water supply operation, the water in the medium temperature layer (M) in the tank (30) is heated to a first temperature by the heating section (13). This reduces the temperature difference between the water flowing into the heating section (13) and the water flowing out of the heating section (13). This makes it possible to increase the flow rate of the water heated by the heating section (13), and therefore to increase the amount of high-temperature water supplied to the target (T) of hot water supply.

[0008] A second aspect is a hot water supply device according to the first aspect, characterized in that the first hot water supply operation includes an operation of bypassing the tank (30) and supplying water heated to the first temperature in the heating section (13) to the hot water supply target (T).

[0009] In the second aspect, in the first hot water supply operation, the water heated to the first temperature by the heating section (13) bypasses the tank (30). This makes it possible to suppress the heat of the heated water from being dissipated in the tank (30).

[0010] A third aspect is a hot water supply device according to the first aspect, characterized in that the first hot water supply operation includes an operation of supplying water heated to the first temperature in the heating section (13) to the hot water supply target (T) via a high temperature layer (H) of the tank (30).

[0011] In the third aspect, in the first hot water supply operation, the water heated to the first temperature by the heating part (13) can be stored in the tank (30).

[0012] A fourth aspect is a hot water supply device according to the first or second aspect, characterized in that the first hot water supply operation includes an operation of supplying at least a portion of the water heated in the heating section (13) to the hot water supply target (T) by bypassing the tank (30), while simultaneously supplying water from a high temperature layer (H) of the tank (30) to the hot water supply target (T).

[0013] In the fourth aspect, water heated to the first temperature by the heating section (13) is supplied to the hot water supply target (T) bypassing the tank (30). It is possible to prevent the heat of the heated water from being dissipated in the tank (30). In addition, by supplying water to the high-temperature layer (H) in the tank (30) to the hot water supply target (T), a large amount of high-temperature water can be supplied to the hot water supply target.

[0014] A fifth aspect is any one of the first to fourth aspects, wherein a first storage portion (36) corresponding to the high temperature layer (H), a second storage portion (34) corresponding to the low temperature layer (L), and an intermediate storage portion (35) corresponding to the medium temperature layer (M) are formed inside the tank (30), and the hot water supply flow path (40) includes an inflow flow path (41) communicating between a water source (S) and the second storage portion (34), an outflow flow path (42) communicating with the first storage portion (36), and an intermediate storage portion (35) corresponding to the medium temperature layer (M). The hot water supply device includes a first heating flow path (43) communicating between a reservoir section (35) and an inlet side of the heating section (13), a bypass flow path (61) communicating between an outlet side of the heating section (13) and an outlet end of the outlet flow path (42), a first return flow path (45) communicating between the outlet side of the heating section (13) and the first storage section (36), and a first adjustment mechanism (53) adjusting at least each flow rate of the outlet flow path (42) and the bypass flow path (61).

[0015] In the fifth aspect, a hot water supply flow path (40) for performing a first hot water supply operation is configured. In the first hot water supply operation, the first adjustment mechanism (53) can adjust the amount of water supplied to the hot water supply target (T) by bypassing the tank (30) and the amount of water supplied to the hot water supply target (T) from the high temperature layer (H) of the tank (30).

[0016] A sixth aspect is the hot water supply device of the fifth aspect, characterized in that the hot water supply flow path (40) includes a second return flow path (46) communicating between the outlet side of the heating section (13) and the intermediate storage section (35), a second heating flow path (44) communicating between the second storage section (34) and the inlet side of the heating section (13), a first switching mechanism (51) switching between a communication state between the inlet side of the heating section (13) and one of the first heating flow path (43) and the second heating flow path (44), and a second switching mechanism (52) switching between a communication state between the outlet side of the heating section (13) and one of the first return flow path (45) and the second return flow path (46).

[0017] In the sixth aspect, a hot water supply flow path (40) is configured for performing a plurality of other operations in addition to the first hot water supply operation.

[0018] A seventh aspect is a hot water supply apparatus according to the sixth aspect, characterized in that the hot water supply flow path (40) is configured to perform a second hot water supply operation in which water from the medium temperature layer (M) of the intermediate storage section (35) is supplied to the hot water supply target (T) via the second return flow path (46) and the bypass flow path (61), while at the same time supplying water from the high temperature layer (H) of the tank (30) to the hot water supply target (T).

[0019] In the seventh aspect, the second return flow path (46) is used as two flow paths. First, the second return flow path (46) is used as a flow path for returning water heated in the heating section (13) to the medium temperature layer (M). Second, the second return flow path (46) is used as a flow path for supplying medium-temperature water in the medium temperature layer (M) to the hot water supply target (T) in the second hot water supply operation.

[0020] An eighth aspect is a hot water supply device according to the sixth or seventh aspect, characterized in that the hot water supply flow path (40) is configured to perform a third hot water supply operation in which water in the low temperature layer (L) of the second storage section (34) is heated to a second temperature lower than the first temperature by the heating section (13) and supplied to the hot water supply target, while at the same time supplying water in the high temperature layer (H) of the tank (30) to the hot water supply target (T).

[0021] In the eighth aspect, in the third hot water supply operation, low-temperature water is heated to medium-temperature water by the heating section (13), and the heated medium-temperature water and high-temperature water in the high-temperature layer (H) can be supplied to the hot water supply target (T).

[0022] A ninth aspect is a hot water supply device according to the eighth aspect, characterized in that the third hot water supply operation includes an operation of returning a portion of the water heated in the heating section (13) to the medium temperature layer (M) of the intermediate storage section (35).

[0023] In the ninth aspect, in the third hot water supply operation, medium temperature water can be stored in the medium temperature layer (M).

[0024] A tenth aspect is a hot water supply device according to the eighth or ninth aspect, characterized in that it includes a judgment unit (29) that judges whether to execute the first hot water supply operation or the third hot water supply operation based on the heat required by the hot water supply target (T) and the heat storage amount in the tank (30).

[0025] In the tenth aspect, it is possible to determine whether the first hot water supply operation or the third hot water supply operation is to be performed based on the amount of heat required by the hot water supply target (T) and the amount of heat stored in the tank (30).

[0026] An eleventh aspect is a hot water supply device according to the tenth aspect, characterized in that the hot water supply flow path (40) is configured to execute a second hot water supply operation in which water from the medium temperature layer (M) of the intermediate storage section (35) is supplied to the hot water supply target (T) via the second return flow path (46) and the bypass flow path (61) while simultaneously supplying water from the high temperature layer (H) of the tank (30) to the hot water supply target (T), and the determination unit (29) determines which of the first hot water supply operation, the second hot water supply operation, and the third hot water supply operation to execute based on the heat required by the hot water supply target (T) and the heat stored in the tank (30).

[0027] In the eleventh aspect, it is possible to determine which of the first hot water supply operation, the second hot water supply operation, and the third hot water supply operation to perform, based on the amount of heat required by the hot water supply target (T) and the amount of heat stored in the tank (30).

[0028] A twelfth aspect is a hot water supply device characterized in that, in any one of the fifth to eleventh aspects, the hot water supply flow path (40) is configured to perform a fourth hot water supply operation in which water in the low temperature layer (L) of the second storage section (34) is heated to the first temperature in the heating section (13) and supplied to a hot water supply target (T).

[0029] In the twelfth aspect, in the fourth hot water supply operation, low-temperature water is heated to high-temperature water by the heating section (13), and the heated high-temperature water can be supplied to the target of hot water supply (T).

[0030] A thirteenth aspect is a hot water supply apparatus according to the twelfth aspect, characterized in that it further includes a control device (25) that executes the fourth hot water supply operation when there is a demand for hot water from the target (T) when there is a shortage of water in the high temperature layer (H) and the medium temperature layer (M) of the tank (30).

[0031] In the thirteenth aspect, when there is a demand for hot water from the target (T) in a state where the high-temperature water and the low-temperature water are insufficient in the tank (30), the control device (25) executes the fourth hot water supply operation.

[0032] A 14th aspect is a hot water supply device in any one of the 5th to 13th aspects, characterized in that the hot water supply flow path (40) has a first water supply path (63) communicating with the outlet end of the outlet flow path (42), a main water supply path (65) communicating the first water supply path (63) with the hot water supply target (T), a second water supply path (64) communicating the intermediate storage section (35) with the inlet end of the main water supply path (65), and a second adjustment mechanism (54) that adjusts at least the flow rate of the second water supply path (64) out of the flow rate of the first water supply path (63) and the flow rate of the second water supply path (64).

[0033] In the fourteenth aspect, the medium-temperature water in the medium-temperature layer (M) of the intermediate storage section (35) can be directly supplied to the hot water supply target (T) via the second water supply passage (64) and the main water supply passage (65). The amount of medium-temperature water supplied from the medium-temperature layer (M) to the hot water supply target (T) can be adjusted by the second adjustment mechanism (54).

[0034] A fifteenth aspect is the hot water heating apparatus of the fourteenth aspect, characterized in that the hot water supply flow path (40) has a third supply water path (66) communicating with the inflow flow path (41) and the second supply water path (64), and a third adjustment mechanism (55) that adjusts at least the flow rate of the third supply water path (66) out of the flow rate of the second supply water path (64) and the flow rate of the third supply water path (66).

[0035] In the fifteenth aspect, the low-temperature water in the inflow passage (41) can be directly supplied to the hot water supply target (T) via the third water supply passage (66), the second water supply passage (64), and the main water supply passage (65). The amount of low-temperature water supplied from the inflow passage (41) to the hot water supply target (T) can be adjusted by the third adjustment mechanism (55). [Brief description of the drawings]

[0036] [Figure 1] FIG. 1 is a piping diagram showing the overall configuration of a hot water supply unit according to an embodiment. [Diagram 2] FIG. 2 is a graph showing the relationship between the temperature inside the tank and the state of hot water stored in the tank. [Diagram 3] FIG. 3 is a diagram showing a schematic diagram of the hot water storage state in the tank. [Figure 4] FIG. 4 is a schematic piping diagram of the hot water supply system, showing the first hot water storage operation. [Diagram 5] FIG. 5 is a schematic piping diagram of the hot water supply system, showing the second hot water storage operation. [Figure 6] FIG. 6 is a schematic piping diagram of the hot water supply system, showing the third hot water storage operation. [Figure 7] FIG. 7 is a schematic piping diagram of the hot water supply system, showing the first hot water supply operation. [Figure 8] FIG. 8 is a schematic piping diagram of the hot water supply system, showing the second hot water supply operation. [Figure 9] FIG. 9 is a schematic piping diagram of the hot water supply system, showing the third hot water supply operation. [Figure 10] FIG. 10 is a schematic piping diagram of the hot water supply system, showing the fourth hot water supply operation. [Figure 11]FIG. 11 is a piping diagram showing the overall configuration of a hot water supply unit according to a modified example. [Figure 12] FIG. 12 is a schematic piping diagram of a hot water supply apparatus according to a modified example, showing a first hot water supply operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or its uses.

[0038] <<Embodiment>> The hot water supply device (20) of the present disclosure is applied to a heat pump type hot water supply unit (1). The hot water supply unit (1) heats water supplied from a water source (S) and stores the heated hot water in a tank (30). The hot water in the tank (30) is supplied to a predetermined hot water supply target (T). The water source (S) is a line through which water is supplied, and includes a water supply system, etc. The hot water supply target (T) is an object where hot water is used, and includes a shower, a faucet, a bathtub, etc.

[0039] As shown in FIG. 1, the hot water supply unit (1) includes a heat source device (10), a hot water supply device (20), and a controller (25). The heat source device (10) includes a refrigerant circuit (11). The hot water supply device (20) includes a hot water supply flow path (40). The hot water supply flow path (40) is a water flow path formed between a water source (S) and a hot water supply target (T). The hot water supply flow path (40) is an overall water flow path of the hot water supply device (20). The hot water supply unit (1) includes a water heat exchanger (13). The refrigerant circuit (11) and the hot water supply flow path (40) are connected to each other via the water heat exchanger (13). The water heat exchanger (13) is used for both the heat source device (10) and the hot water supply device (20).

[0040] <Heat source device> The heat source device (10) is a heat source for generating hot water. A refrigerant circuit (11) of the heat source device (10) is filled with a refrigerant. For example, a fluorocarbon-based refrigerant or a natural refrigerant such as propane is used as the refrigerant. In the refrigerant circuit (11), a vapor compression refrigeration cycle is performed by circulating the refrigerant. Strictly speaking, the refrigerant circuit (11) performs a so-called subcritical cycle in which the pressure of a high-pressure refrigerant is lower than the critical pressure.

[0041] The refrigerant circuit (11) includes a compressor (12), a water heat exchanger (13), an expansion valve (14), and an air heat exchanger (15).

[0042] The compressor (12) draws in and compresses a low-pressure refrigerant, and discharges the refrigerant compressed to a high pressure.

[0043] The water heat exchanger (13) constitutes a heating section that heats the water in the hot water supply flow path (40). The water heat exchanger (13) has a refrigerant flow path (13a) and a water flow path (13b). The water heat exchanger (13) exchanges heat between the refrigerant flowing in the refrigerant flow path (13a) and the water flowing in the water flow path (13b). The water heat exchanger (13) constitutes a radiator (condenser) in which the refrigerant radiates heat.

[0044] The expansion valve (14) constitutes a pressure reducing mechanism for reducing the pressure of the refrigerant. The expansion valve (14) reduces the pressure of the refrigerant from high pressure to low pressure. The expansion valve (14) is, for example, an electronic expansion valve.

[0045] The air heat exchanger (15) exchanges heat between air and a refrigerant. The air heat exchanger (15) is installed outdoors. An outdoor fan (16) is installed near the air heat exchanger (15). Air transported by the outdoor fan (16) passes through the air heat exchanger (15). In the air heat exchanger (15), the refrigerant absorbs heat from the outdoor air and evaporates. The air heat exchanger (15) constitutes an evaporator.

[0046] <Hot water supply equipment> The hot water supply device (20) includes a hot water supply flow path (40). The hot water supply flow path (40) includes a water heat exchanger (13), a tank (30), and a pump (21).

[0047] <Water heat exchanger> The water flow path (13b) of the water heat exchanger (13) is connected to the hot water supply flow path (40). In the water heat exchanger (13), water is heated by the refrigerant dissipating heat.

[0048] <tank> The tank (30) is a hollow container. The tank (30) is formed in a vertically long cylindrical shape. The tank (30) has a cylindrical body (31), a bottom (32) closing the lower end side of the body (31), and a top (33) closing the upper end side of the body (31). A storage section for storing water is formed inside the tank (30). Specifically, inside the tank (30), a lower storage section (34), an intermediate storage section (35), and an upper storage section (36) are formed in this order from the bottom (32) to the top (33). The upper storage section (36) is a first storage section located at the upper part of the tank (30). The lower storage section (34) is a second storage section located at the lower part of the tank (30). The intermediate reservoir (35) is located between the lower reservoir (34) and the upper reservoir (36).

[0049] In a fourth hot water storage state (see FIG. 3), which will be described in detail later, a high temperature layer (H) is formed in the upper storage section (36), a middle layer (M) is formed in the middle storage section (35), and a low temperature layer (L) is formed in the lower storage section (34). Water of different temperatures is stored in the high temperature layer (H), middle temperature layer (M), and low temperature layer (L). The temperature of the water (also called high temperature water) in the high temperature layer (H) is, for example, about 60°C. The temperature of the water (also called middle temperature water) in the middle temperature layer (M) is, for example, about 40°C. The temperature of the water (also called low temperature water) in the low temperature layer (L) is, for example, about 10°C.

[0050] <pump> The pump (21) is a transport device that transports water in the hot water supply flow path (40). The pump (21) is provided in the main heating flow path (47). <Hot water supply channel> The hot water supply flow path (40) includes an inlet pipe (41), an outlet pipe (42), a first heating pipe (43), a second heating pipe (44), a first return pipe (45), a second return pipe (46), a main heating flow path (47), a first three-way valve (51), and a second three-way valve (52).

[0051] The inflow pipe (41) is an inflow passage that connects the water source (S) and the lower reservoir (34). An inflow end of the inflow pipe (41) is connected to, for example, a water supply pipe. An outflow end of the inflow pipe (41) is connected to the bottom (32) of the tank (30). The inflow pipe (41) appropriately supplies low-temperature water from the water source (S) to the tank (30). Specifically, when water from the tank (30) is supplied to the hot water supply target (T), the internal pressure of the tank (30) decreases. As a result, the pressure difference between the water source (S) and the tank (30) increases, and the low-temperature water from the water source (S) is replenished to the tank (30) via the inflow pipe (41).

[0052] The outflow pipe (42) is an outflow passage that connects the upper storage portion (36) with the hot water supply target (T). An inflow end of the outflow pipe (42) is connected to the top (33) of the tank (30). An outflow end of the outflow pipe (42) is connected to the first mixing valve (53).

[0053] The first heating pipe (43) is a first heating flow path that connects the intermediate storage section (35) and the inlet side of the water heat exchanger (13). One end of the first heating pipe (43) is connected to the middle of the second return pipe (46). The other end of the second heating pipe (44) is connected to a first port of the first three-way valve (51).

[0054] The second heating pipe (44) is a second heating flow path that connects the lower reservoir (34) and the inlet side of the water heat exchanger (13). One end of the second heating pipe (44) is connected to the bottom (32) of the tank (30). The other end of the second heating pipe (44) is connected to the second port of the first three-way valve (51).

[0055] Note that one end of the second heating pipe (44) may be directly connected to the inlet pipe (41) instead of being connected to the bottom (32) of the tank (30). In this way, water in the lower reservoir (34) in the tank (30) can be drawn through the inlet pipe (41) and then through the second heating pipe (44). As a result, the number of pipes connected to the tank (30) can be reduced, and the structure of the tank (30) can be simplified.

[0056] The first return pipe (45) is a first return flow path that connects the outlet side of the water heat exchanger (13) and the upper reservoir (36). One end of the first return pipe (45) is connected to the top of the tank (30). The other end of the first return pipe (45) is connected to the first port of the second three-way valve (52).

[0057] The second return pipe (46) is a second return flow path that connects the outlet side of the water heat exchanger (13) and the intermediate storage section (35). One end of the second return pipe (46) is connected to the body section (31) of the tank (30). The other end of the second return pipe (46) is connected to the second port of the second three-way valve (52).

[0058] The main heating flow path (47) is a flow path in which the water heat exchanger (13) is provided. The water flow path (13b) of the water heat exchanger (13) is connected to the middle of the main heating flow path (47). One end of the main heating flow path (47) is connected to the third port of the first three-way valve (51). The other end of the main heating flow path (47) is connected to the third port of the second three-way valve (52). A pump (21) is provided in the main heating flow path (47) upstream of the water heat exchanger (13).

[0059] The first three-way valve (51) is a first switching mechanism that switches between a communication state between the inlet side of the water heat exchanger (13) and one of the first heating pipe (43) and the second heating pipe (44). The first three-way valve (51) has a first port, a second port, and a third port. The first three-way valve (51) is switched between a first state (a state indicated by a solid line in FIG. 1) and a second state (a state indicated by a dashed line in FIG. 1).

[0060] The first three-way valve (51) in the first state communicates the third port with the first port and blocks the third port from the second port. Specifically, the first three-way valve (51) in the first state communicates the inlet side of the water heat exchanger (13) with the first heating pipe (43) and blocks the inlet side of the water heat exchanger (13) from the second heating pipe (44).

[0061] The first three-way valve (51) in the second state communicates the third port with the second port and blocks the third port from the first port. Specifically, the first three-way valve (51) in the second state communicates the inlet side of the water heat exchanger (13) with the second heating pipe (44) and blocks the inlet side of the water heat exchanger (13) from the first heating pipe (43).

[0062] The second three-way valve (52) is a second switching mechanism that switches between a communication state between the outlet side of the water heat exchanger (13) and one of the first return pipe (45) and the second return pipe (46). The second three-way valve (52) has a first port, a second port, and a third port. The second three-way valve (52) is switched between a first state (a state indicated by a solid line in FIG. 1) and a second state (a state indicated by a dashed line in FIG. 1).

[0063] The second three-way valve (52) in the first state communicates the third port with the first port and blocks the third port from the second port. Specifically, the first three-way valve (51) in the first state communicates the outlet side of the water heat exchanger (13) with the first return pipe (45) and blocks the outlet side of the water heat exchanger (13) from the second return pipe (46).

[0064] The second three-way valve (52) in the second state communicates the third port with the second port and blocks the third port from the first port. Specifically, the second three-way valve (52) in the second state communicates the outlet side of the water heat exchanger (13) with the second return pipe (46) and blocks the outlet side of the water heat exchanger (13) from the first return pipe (45).

[0065] The hot water supply flow path (40) has a bypass flow path (61), a branch flow path (62), a first water supply path (63), a second water supply path (64), a main water supply path (65), a first mixing valve (53), and a second mixing valve (54).

[0066] The bypass flow path (61) is a flow path for supplying water heated in the water heat exchanger (13) to the hot water supply target (T) while bypassing the tank (30). One end of the bypass flow path (61) is connected to the outlet end of the main heating flow path (47). The other end of the bypass flow path (61) is connected to the first mixing valve (53).

[0067] The branch flow path (62) is a flow path to which a part of the water heated in the water heat exchanger (13) can be diverted. One end of the branch flow path (62) is connected to the outlet end of the main heating flow path (47). The other end of the branch flow path (62) is connected to the third port of the second three-way valve (52). In this example, all or a part of the water heated in the water heat exchanger (13) flows through the bypass flow path (61). The remainder of the water heated in the water heat exchanger (13) flows through the branch flow path (62).

[0068] The first water supply passage (63) is connected to the bypass flow path (61) and the outlet side of the outlet pipe (42). One end of the first water supply passage (63) is connected to the first mixing valve (53). The other end of the first water supply passage (63) is connected to the second mixing valve (54).

[0069] The second water supply passage (64) is a flow path for directly supplying water from the water source (S) to the hot water supply target (T). One end of the second water supply passage (64) is connected to the inlet pipe (41). The other end of the second water supply passage (64) is connected to the second mixing valve (54).

[0070] The main water supply passage (65) is a flow path for supplying water adjusted to a predetermined temperature to the target of hot water supply (T). One end of the main water supply passage (65) is connected to the second mixing valve (54). The other end of the main water supply passage (65) is in communication with the target of hot water supply (T).

[0071] The first mixing valve (53) is connected to the bypass passage (61), the outlet pipe (42), and the main water supply passage (65). The first mixing valve (53) adjusts the mixing ratio of the water in the bypass passage (61) and the outlet pipe (42). The water mixed in the first mixing valve (53) flows out into the first water supply passage (63).

[0072] The first mixing valve (53) is a first adjustment mechanism that adjusts the flow rate of water in the bypass flow path (61) and the flow rate of water in the outflow pipe (42). The first mixing valve (53) is configured to be able to open and close the outflow end of the bypass flow path (61) and the outflow end of the outflow pipe (42). When the flow rate of water in the bypass flow path (61) is adjusted by the first mixing valve (53), the flow rate of water flowing through the branch flow path (62) and therefore the first return pipe (45) is adjusted. The first mixing valve (53) is also used to adjust the flow rate of water in the first return pipe (45).

[0073] The second mixing valve (54) is connected to the first water supply passage (63), the second water supply passage (64), and the main water supply passage (65). The second mixing valve (54) adjusts the mixing ratio of the water in the first water supply passage (63) and the second water supply passage (64). The water mixed in the second mixing valve (54) flows out into the main water supply passage (65). The second mixing valve (54) adjusts the flow rate of the water in the first water supply passage (63) and the flow rate of the water in the second water supply passage (64). The second mixing valve (54) is configured to be able to open and close the outflow end of the first water supply passage (63) and the outflow end of the second water supply passage (64), respectively.

[0074] <Temperature Sensor> A first temperature sensor (71) and a second temperature sensor (72) are provided inside the tank (30). The first temperature sensor (71) is disposed in the upper storage portion (36) corresponding to the high temperature layer (H). The first temperature sensor (71) detects the temperature of the water in the upper storage portion (36) (first detected temperature (T1)). The second temperature sensor (72) is disposed in the intermediate storage portion (35) corresponding to the medium temperature layer (M). The second temperature sensor (72) detects the temperature of the water in the intermediate storage portion (35) (second detected temperature (T2)).

[0075] A third temperature sensor (73) is provided in the main heating flow path (47). The third temperature sensor (73) is provided at an outlet of the water heat exchanger (13) in the main heating flow path (47). The third temperature sensor (73) detects the temperature of water at the outlet of the water flow path (13b) of the water heat exchanger (13) (hereinafter also referred to as outlet temperature (To)).

[0076] <controller> The controller (25) is a control device that controls the heat source device (10) and the hot water supply device (20). The controller (25) has a microcomputer and a memory device (specifically, a semiconductor memory) that stores software for operating the microcomputer.

[0077] Strictly speaking, the controller (25) controls the compressor (12), the expansion valve (14), and the outdoor fan (16). The controller (25) controls the pump (21), the first three-way valve (51), the second three-way valve (52), the first mixing valve (53), and the second mixing valve (54). The controller (25) controls the hot water supply flow path (40) to switch between various operations.

[0078] The controller (25) includes an input unit (26), a setting unit (27), a temperature determination unit (28), and a demand determination unit (29).

[0079] A signal indicating a demand for hot water supply from the hot water supply target (T) is input to the input unit (26). For example, a user operates an operation unit, whereby a signal is input from the operation unit to the input unit (26).

[0080] The setting unit (27) sets a first set temperature (Ts1), a second set temperature (Ts2), a hot water supply set temperature (Ths), a first target temperature (To1), and a second target temperature (To2). The first set temperature (Ts1) is a temperature for determining whether or not a high temperature layer (H) exists in the upper storage portion (36) of the tank (30). The second set temperature (Ts2) is a temperature for determining whether or not a medium temperature layer (M) exists in the intermediate storage portion (35) of the tank (30). The hot water supply set temperature (Ths) is a target temperature of water to be supplied to the hot water supply target (T).

[0081] The first set temperature (Ts1) and the second set temperature (Ts2) may be fixed values ​​that are set in advance when the hot water supply unit (1) is installed. The first set temperature (Ts1) and the second set temperature (Ts2) may be variable values ​​that can be changed as appropriate by the user. The first set temperature (Ts1) and the second set temperature (Ts2) may be values ​​that are determined by so-called learning control based on the daily usage of the hot water supply unit (1). Specifically, in the learning control, optimal values ​​of the first set temperature (Ts1) and the second set temperature (Ts2) are found based on the type of hot water supply target (T) used by the user, the hot water supply set temperature (Ths) that the user sets as appropriate, and the like.

[0082] The temperature determination unit (28) determines the state of hot water stored in the tank (30). The temperature determination unit (28) determines the state of hot water stored in the tank (30) based on the first detected temperature (T1), the second detected temperature (T2), the first set temperature (Ts1), and the second set temperature (Ts2). The method of this determination will be described in detail later.

[0083] The demand determination unit (29) determines the amount of heat (Qd) required to be supplied to the hot water supply target (T) and the amount of heat stored in the tank (30). The demand determination unit (29) determines which hot water supply operation to execute based on these indices.

[0084] - Driving operation - The operation of the hot water supply unit (1) will be described in detail. The hot water supply unit (1) executes a hot water storage operation and a hot water supply operation. The hot water storage operation is an operation in which water heated by the water heat exchanger (13) is stored in the tank (30). The hot water storage operation is basically executed when there is no demand for hot water from the hot water supply target (T). In the hot water storage operation, hot water is not supplied to the hot water supply target (T). The hot water storage operation includes a first hot water storage operation, a second hot water storage operation, and a third hot water storage operation, which will be described in detail later.

[0085] The hot water supply operation is an operation in which at least one of hot water in the tank (30) and hot water heated in the water heat exchanger (13) is supplied to the hot water supply target (T). The hot water supply operation is performed when there is a demand for hot water from the hot water supply target (T). The hot water supply operation includes a first hot water supply operation, a second hot water supply operation, a third hot water supply operation, and a fourth hot water supply operation, which will be described in detail later.

[0086] <Determining hot water storage status> In the hot water supply unit (1), the hot water storage state of the tank (30) is determined as appropriate. In the hot water storage operation, each hot water storage operation is switched based on the result of the determination of the hot water storage state. The method of determining the hot water storage state will be described with reference to Figs. 1 to 3.

[0087] The hot water storage state is determined based on the amount of high-temperature hot water stored in the tank (30) and the amount of low-temperature hot water stored in the tank (30). Specifically, the hot water storage state of the tank (30) is determined based on a first detected temperature (T1), a second detected temperature (T2), a first set temperature (Ts1), and a second set temperature (Ts2). The first set temperature (Ts1) is a set value to be compared with the first detected temperature (T1). The first set temperature (Ts1) is set to a temperature (e.g., 60° C.) of high-temperature water corresponding to the high-temperature layer (H). The second set temperature (Ts2) is a set value to be compared with the second detected temperature (T2). The second set temperature (Ts2) is set to a temperature (e.g., 40° C.) of medium-temperature water corresponding to the medium-temperature layer (M). The temperature determination unit (28) determines whether the hot water storage state of the tank (30) is the first hot water storage state, the second hot water storage state, the third hot water storage state, or the fourth hot water storage state, as follows.

[0088] [First hot water storage state] When the first detected temperature (T1) is lower than the first set temperature (Ts1) and the second detected temperature (T2) is lower than the second set temperature (Ts2), the first hot water storage state is determined. The first hot water storage state is a state in which the amount of high-temperature hot water stored in the tank (30) is insufficient and the amount of medium-temperature hot water stored in the tank (30) is insufficient. Thus, in the first hot water storage state, a low-temperature layer (L) is formed in the tank (30).

[0089] [Second hot water storage state] When the first detected temperature (T1) is equal to or higher than the first set temperature (Ts1) and the second detected temperature (T2) is lower than the second set temperature (Ts2), the second hot water storage state is determined. The second hot water storage state is a state in which the amount of high-temperature hot water stored in the tank (30) is sufficient and the amount of medium-temperature hot water stored is insufficient. Thus, in the second hot water storage state, a high-temperature layer (H) and a low-temperature layer (L) are formed in the tank (30).

[0090] [Third hot water storage state] When the first detected temperature (T1) is lower than the first set temperature (Ts1) and the second detected temperature (T2) is equal to or higher than the second set temperature (Ts2), the third hot water storage state is determined. The third hot water storage state is a state in which the amount of high-temperature hot water stored in the tank (30) is insufficient and the amount of medium-temperature hot water stored is sufficient. Thus, in the third hot water storage state, a medium-temperature layer (M) is formed in the tank (30).

[0091] [Fourth hot water storage state] When the first detected temperature (T1) is equal to or higher than the first set temperature (Ts1) and the second detected temperature (T2) is equal to or higher than the second set temperature (Ts2), a fourth hot water storage state is determined. The fourth hot water storage state is a state in which the tank (30) is full of high-temperature hot water and full of medium-temperature hot water. Thus, in the fourth hot water storage state, a high-temperature layer (H), a medium-temperature layer (M), and a low-temperature layer (L) are formed in the tank (30).

[0092] <Hot water storage operation> The hot water storage operation will be described in detail. Any one of a first hot water storage operation, a second hot water storage operation, and a third hot water storage operation is performed. In each hot water storage operation, the heat source device (10) shown in FIG. 1 is operated, and the pump (21) is turned on.

[0093] When the heat source device (10) is in the hot water storage operation, the compressor (12) is driven and the opening degree of the expansion valve (14) is adjusted. A refrigeration cycle is performed in the refrigerant circuit (11). Specifically, the refrigerant compressed by the compressor (12) flows through the refrigerant passage (13a) of the water heat exchanger (13). In the water heat exchanger (13), the water in the refrigerant passage (13a) dissipates heat to the water in the water passage (13b). As a result, the refrigerant in the refrigerant passage (13a) condenses. The refrigerant that has dissipated heat in the water heat exchanger (13) is reduced in pressure by the expansion valve (14) and then flows through the air heat exchanger (15). In the air heat exchanger (15), the refrigerant evaporates in the air heat exchanger (15). The evaporated refrigerant is sucked into the compressor (12).

[0094] In the hot water supply apparatus (20) during the hot water storage operation, the pump (21) is operated. The water in the tank (30) is heated in the water heat exchanger (13) and then returned to the tank (30).

[0095] In the hot water storage operation, the hot water supply unit (1) is controlled so that the water flowing out of the water flow path (13b) of the water heat exchanger (13) has a predetermined temperature. Specifically, in the hot water storage operation, control is performed so that the outlet temperature (To) of the water flow path (13b) detected by the third temperature sensor (73) approaches a target temperature. Specifically, the outlet temperature (To) is adjusted based on the heating capacity of the heat source device (10) and the flow rate of water in the water flow path (13b).

[0096] [First hot water storage operation] When the tank (30) is determined to be in a first hot water storage state in a state in which there is no demand for hot water supply (T), the first hot water storage operation shown in Fig. 4 is executed. In other words, when the amount of high-temperature hot water and the amount of medium-temperature hot water stored in the tank (30) are insufficient, the first hot water storage operation is executed. The first hot water storage operation is an operation in which low-temperature water is heated to high-temperature water and the heated high-temperature water is stored in the tank (30).

[0097] In the first hot water storage operation, the heat source device (10) is operated. The first three-way valve (51) is in the second state, and the second three-way valve (52) is in the first state. The first mixing valve (53) closes the outlet ends of the outlet pipe (42) and the bypass passage (61). The second mixing valve (54) closes the outlet ends of the first water supply passage (63) and the second water supply passage (64).

[0098] When the pump (21) is operated, low-temperature water in the lower reservoir (34) in the tank (30) flows out into the second heating pipe (44). This water flows through the water flow path (13b) of the water heat exchanger (13) and is heated to high-temperature water. In the first hot water storage operation, control is performed to bring the outlet temperature (To) closer to a first target temperature (To1) (first temperature). The first target temperature (To1) is a predetermined temperature equal to or higher than the hot water supply set temperature (Ths) set in the setting unit (27). The first target temperature (To1) is preferably a predetermined temperature equal to or higher than the first set temperature (Ts) set in the setting unit (27).

[0099] The high-temperature water heated to the first target temperature (To1) in the water heat exchanger (13) flows through the branch flow path (62) and the first return pipe (45), and enters the upper reservoir (36) of the tank (30).

[0100] By the above-described first hot water storage operation, a high temperature layer (H) is formed in the tank (30). By preferentially storing high-temperature water in the tank (30) in this manner, it is possible to meet the demand for hot water from the hot water supply target (T).

[0101] [Second hot water storage operation] When the tank (30) is determined to be in the second hot water storage state in a state in which there is no demand for hot water supply (T), the second hot water storage operation shown in Fig. 5 is executed. In other words, when the amount of high-temperature hot water stored in the tank (30) is sufficient and the amount of medium-temperature hot water stored is insufficient, the second hot water storage operation is executed. The second hot water storage operation is an operation in which low-temperature water is heated to medium-temperature water and the heated medium-temperature water is stored in the tank (30).

[0102] In the second hot water storage operation, the heat source device (10) is operated. The first three-way valve (51) is in the second state, and the second three-way valve (52) is in the second state. The first mixing valve (53) closes the outlet ends of the outlet pipe (42) and the bypass flow path (61). The second mixing valve (54) closes the outlet ends of the first water supply path (63) and the second water supply path (64).

[0103] When the pump (21) is operated, low-temperature water in the lower reservoir (34) in the tank (30) flows out into the second heating pipe (44). This water flows through the water flow path (13b) of the water heat exchanger (13) and is heated to medium-temperature water. In the second hot water storage operation, control is performed to bring the outlet temperature (To) closer to a second target temperature (To2) (second temperature). The second target temperature (To2) is a predetermined temperature lower than the hot water supply set temperature (Ths) set in the setting unit (27). The second target temperature (To2) is preferably a predetermined temperature equal to or higher than the second set temperature (Ts) set in the setting unit (27).

[0104] The medium-temperature water heated to the second target temperature (To2) in the water heat exchanger (13) flows through the branch flow path (62) and the second return pipe (46), and enters the intermediate storage portion (35) of the tank (30).

[0105] As a result of the second hot water storage operation as described above, a medium temperature layer (M) is formed in the tank (30). As a result, a high temperature layer (H), a medium temperature layer (M), and a low temperature layer (L) are formed in the tank (30). As a result, the hot water storage state of the tank (30) can be quickly transitioned to a fourth hot water storage state (see FIG. 3).

[0106] [Third hot water storage operation] When the tank (30) is determined to be in the third hot water storage state in a state where there is no demand for hot water supply (T), the third hot water storage operation shown in Fig. 6 is executed. In other words, when the amount of high-temperature hot water stored in the tank (30) is insufficient and the amount of medium-temperature hot water stored is sufficient, the third hot water storage operation is executed. The third hot water storage operation is an operation in which medium-temperature water is heated to high-temperature water and the heated high-temperature water is stored in the tank (30).

[0107] In the third hot water storage operation, the heat source device (10) is operated. The first three-way valve (51) is in the first state, and the second three-way valve (52) is in the first state. The first mixing valve (53) closes the outlet ends of the outlet pipe (42) and the bypass flow path (61). The second mixing valve (54) closes the outlet ends of the first water supply passage (63) and the second water supply passage (64).

[0108] When the pump (21) is operated, the medium-temperature water in the intermediate storage portion (35) in the tank (30) flows out into the first heating pipe (43). This water flows through the water flow path (13b) of the water heat exchanger (13) and is heated to high-temperature water. In the third hot water storage operation, the outlet temperature (To) is controlled to approach the first target temperature (To1) (first temperature).

[0109] The high-temperature water heated to the first target temperature (To1) in the water heat exchanger (13) flows through the branch flow path (62) and the first return pipe (45), and enters the upper reservoir (36) of the tank (30).

[0110] As a result of the third hot water storage operation as described above, a high temperature layer (H) is formed in the tank (30). As a result, a high temperature layer (H), a medium temperature layer (M), and a low temperature layer (L) are formed in the tank (30). As a result, the hot water storage state of the tank (30) can be quickly transitioned to a fourth hot water storage state (see FIG. 3).

[0111] <Hot water operation> The hot water supply operation will be described in detail. In the hot water supply operation, any one of a first hot water supply operation, a second hot water supply operation, a third hot water supply operation, and a fourth hot water supply operation is executed. Each hot water supply operation is executed when a signal indicating a demand for hot water supply target (T) is input to the input unit (26) of the controller (25). In each hot water supply operation, hot water is supplied to the hot water supply target (T) by at least the water pressure of the water source (S).

[0112] In each hot water supply operation, the hot water supply unit (1) is controlled so that the temperature of the supply water supplied to the hot water supply target (T) approaches the hot water supply set temperature (Ths). Specifically, the temperature of the supply water is adjusted based on the flow rate of the water in the bypass flow path (61) and the flow rate of the water in the outflow pipe (42). In addition, the temperature of the supply water is adjusted based on the flow rate of the water in the first supply water path (63) and the flow rate of the water in the second supply water path (64). The flow rates of the water in the bypass flow path (61) and the outflow pipe (42) are adjusted by the first mixing valve (53). The flow rates of the water in the first supply water path (63) and the second supply water path (64) are adjusted by the second mixing valve (54).

[0113] In addition, in the first hot water supply operation, the third hot water supply operation, and the fourth hot water supply operation, similar to the hot water storage operation described above, control is performed to bring the outlet temperature (To) of the water flow path (13b) of the water heat exchanger (13) closer to a target temperature.

[0114] [First hot water supply operation] 7 is an operation in which the medium-temperature water in the tank (30) is heated to high-temperature water and the heated high-temperature water is supplied to the hot water supply target (T). The first hot water supply operation is basically performed when the tank (30) is in the third hot water storage state.

[0115] The first hot water supply operation is executed when the heat storage amount (Qa) in the tank (30) alone is not enough to satisfy the demand of the hot water supply target (T). Specifically, when the demand determination unit (29) determines that the heat storage amount (Qa) is lower than the required heat amount (Qd), the controller (25) executes the first hot water supply operation.

[0116] The first hot water supply operation may be performed under conditions in which the required heat quantity (Qd) of the hot water supply target (T) cannot be predicted by the demand determination unit (29).

[0117] Even if the amount of stored heat (Qa) does not satisfy the required amount of heat (Qd), if high-temperature water is available, the high-temperature water in the tank (30) may be supplied to the hot water supply target (T) through the outflow pipe (42).

[0118] The amount of accumulated heat (Qa) is the amount of accumulated heat of the hot water in the tank (30). The amount of accumulated heat (Qa) is determined based on the first detected temperature (T1) and the second detected temperature (T2). To determine the amount of accumulated heat (Qa) more accurately, three or more temperature sensors may be provided in the tank (30).

[0119] The required calorific value (Qd) is the total calorific value of the water supply required to meet the hot water demand of the hot water supply target (T). The required calorific value (Qd) is calculated based on the type of hot water supply target (T) when a demand for hot water is received from the hot water supply target (T).

[0120] In the first hot water supply operation, the pump (21) is turned on, the first three-way valve (51) is in the first state, and the second three-way valve (52) is in the second state. The first mixing valve (53) opens the outlet end of the outlet pipe (42) and the outlet end of the bypass flow path (61). The second mixing valve (54) opens at least the outlet end of the first water supply path (63).

[0121] When the pump (21) is operated, the medium-temperature water in the medium-temperature layer (M) in the tank (30) flows out into the first heating pipe (43). At this time, low-temperature water from the water source (S) is appropriately supplied to the lower reservoir (34) of the tank (30) through the inlet pipe (41). The medium-temperature water in the first heating pipe (43) flows through the water flow path (13b) of the water heat exchanger (13) and is heated to high-temperature water. In the first hot water supply operation, the outlet temperature (To) is controlled to approach the above-mentioned first target temperature (To1) (first temperature).

[0122] The high-temperature water heated to the first target temperature (To1) in the water heat exchanger (13) is sent to at least the bypass passage (61).

[0123] Meanwhile, high-temperature water in the high-temperature layer (H) in the tank (30) is sent to the outflow pipe (42). The high-temperature water in the bypass passage (61) and the high-temperature water in the outflow pipe (42) are mixed in the first mixing valve. The water mixed in the first mixing valve (53) flows sequentially through the first water supply passage (63) and the main water supply passage (65), and is supplied to the target of hot water supply (T).

[0124] 7, when a portion of the high-temperature water heated in the water heat exchanger (13) is supplied to the bypass flow path (61), the remaining high-temperature water is returned to the upper storage section (36) of the tank (30) through the branch flow path (62) and the first return pipe (45). Thus, the high-temperature water can be stored in the tank (30) while being supplied to the hot water supply target (T).

[0125] On the other hand, when all of the high-temperature water heated in the water heat exchanger (13) is supplied to the bypass flow path (61), no high-temperature water is supplied to the upper reservoir (36). In this manner, in the first hot water supply operation, the surplus high-temperature water heated in the water heat exchanger (13) that does not flow through the bypass flow path (61) is returned to the tank (30).

[0126] The first hot water supply operation is also executed when a signal indicating a demand for hot water supply target (T) is input to the input unit (26) during the third hot water storage operation (see FIG. 6). The third hot water storage operation is an operation in which medium-temperature water is heated to high-temperature water in the water heat exchanger (13). During the third hot water storage operation, the third hot water storage operation can be switched to the first hot water supply operation by adjusting the opening of the first mixing valve (53) and sending high-temperature water to the bypass flow path (61). Therefore, it is possible to switch from the third hot water storage operation to the first hot water supply operation without significantly changing the flow of water in the hot water supply flow path (40).

[0127] As described above, the first hot water supply operation includes an operation of heating the medium-temperature water in the medium-temperature layer (M) of the tank (30) to high-temperature water in the water heat exchanger (13) and supplying the heated high-temperature water to the hot water supply target (T).

[0128] If low-temperature water is heated to high-temperature water in the water heat exchanger (13), the temperature difference between the water at the inlet and the water at the outlet of the water flow path (13b) of the water heat exchanger (13) becomes large. Therefore, in order to heat low-temperature water to high-temperature water, the flow rate of water in the water flow path (13b) needs to be reduced, and it may become impossible to supply a sufficient amount of high-temperature water to the target (T) for hot water supply. Alternatively, in order to ensure the flow rate of water in the water flow path (13b) of the water heat exchanger (13), it is necessary to enlarge the water heat exchanger (13) or increase the heating capacity of the heat source device (10).

[0129] In contrast, in the first hot water supply operation, the medium-temperature water is heated to high-temperature water, so that the temperature difference between the inlet and outlet sides of the water flow path (13b) of the water heat exchanger (13) is relatively small. This makes it possible to ensure a sufficient flow rate of water in the water flow path (13b) of the water heat exchanger (13), and a sufficient amount of high-temperature water can be supplied to the hot water supply target (T). The water heat exchanger (13) does not need to be large.

[0130] In the hot water supply unit (1), low-temperature water is heated to medium-temperature water in the hot water storage operation described above, and medium-temperature water is heated to high-temperature water in the first hot water supply operation. As a result, in this embodiment, the COP (coefficient of performance) of the heat source device (10) can be improved compared to the case where low-temperature water is heated to high-temperature water in the water heat exchanger (13). For example, the COP when low-temperature water of 10° C. is heated to high-temperature water of 65° C. in the water heat exchanger (13) is C1. The COP when low-temperature water of 10° C. is heated to medium-temperature water of 40° C. in the water heat exchanger (13) is C2. The COP when medium-temperature water of 40° C. is heated to high-temperature water of 65° C. is C3. The average value of C2 and C3 is C4. C4 is the average COP by so-called two-stage heating in which low-temperature water is heated to medium-temperature water in the water heat exchanger (13) and then the medium-temperature water is heated to high-temperature water.

[0131] From the trial calculation results, it was found that the COP (C4) of this embodiment can achieve an improvement in COP of about 11% compared to C1.

[0132] In the first hot water supply operation, heated high-temperature water is supplied to the target (T) of hot water supply via the bypass flow path (61). In other words, heated high-temperature water is supplied to the target (T) of hot water supply bypassing the tank (30). If a large amount of high-temperature water is returned to the tank (30), the heat radiation loss in the high-temperature layer (H) in the tank (30) increases. This is because the heat of the high-temperature water is more likely to be released to the outside of the tank (30). In addition, the heat of the high-temperature water is more likely to be transferred to the medium-temperature layer (M) and the low-temperature layer (L).

[0133] In contrast, in the first hot water supply operation, the heated high-temperature water bypasses the tank (30), so that the above-mentioned heat radiation loss can be suppressed.

[0134] [Second hot water supply operation] The second hot water supply operation shown in Fig. 8 is an operation in which the medium-temperature water in the tank (30) is supplied to the hot water supply target (T) without being heated. The second hot water supply operation is basically performed when the tank (30) is in the fourth hot water storage state. When the second hot water supply operation is performed in the fourth hot water storage state, the high-temperature water in the tank (30) is also supplied to the hot water supply target (T). Note that the second hot water supply operation can also be performed when the tank (30) is not in the fourth hot water storage state, as long as a medium-temperature layer (M) is present in the intermediate storage section (35) in the tank (30).

[0135] The second hot water supply operation is executed when the required heat quantity (Qd) of the hot water supply target (T) is relatively small. Specifically, for example, when hot water is supplied only to a faucet or a shower, which is the hot water supply target (T), the second hot water supply operation is executed.

[0136] More specifically, when the demand determination unit (29) determines that the stored heat amount (Qa) is equal to or greater than the required heat amount (Qd) and that the required heat amount (Qd) is lower than a predetermined threshold value (Qs), the controller (25) executes the second hot water supply operation.

[0137] In the second hot water supply operation, the heat source device (10) is stopped, the pump (21) is turned off, the first three-way valve (51) is in the second state, and the second three-way valve (52) is in the second state. The first mixing valve (53) opens the outlet end of the outlet pipe (42) and the outlet end of the bypass flow path (61). The second mixing valve (54) opens at least the outlet end of the first water supply path (63).

[0138] In the second hot water supply operation, water is transported in the hot water supply flow path (40) by the pressure difference between the water source (S) and the hot water supply target (T). The medium-temperature water in the medium-temperature layer (M) in the tank (30) flows through the second return pipe (46). The direction of the water flow in the second return pipe (46) in the second hot water supply operation is opposite to the direction of the water flow in the second return pipe (46) in the third hot water supply operation, the details of which will be described later. The medium-temperature water in the second return pipe (46) is sent to the bypass flow path (61).

[0139] Meanwhile, high-temperature water in the high-temperature layer (H) in the tank (30) is sent to the outlet pipe (42). The medium-temperature water in the bypass passage (61) and the high-temperature water in the outlet pipe (42) are mixed in the first mixing valve (53). The temperature of the mixed water can be adjusted by adjusting the mixing ratio of the two waters. The water mixed in the first mixing valve (53) flows in this order through the first water supply passage (63) and the main water supply passage (65), and is supplied to the target of hot water supply (T).

[0140] As described above, in the second hot water supply operation, the second return pipe (46) is used as a flow path for sending medium-temperature water to the hot water supply target (T). In other words, the second return pipe (46) serves both as a flow path for returning water to the tank in the third hot water supply operation, the details of which will be described later, and as a flow path for supplying water to the hot water supply target (T) in the second hot water supply operation. This makes it possible to simplify the hot water supply flow path (40).

[0141] [Third hot water supply operation] 9 is an operation in which low-temperature water in the tank (30) is heated to medium-temperature water and the heated medium-temperature water is supplied to the hot water supply target (T). The third hot water supply operation is performed when the tank (30) is in the fourth hot water storage state or the second hot water storage state. When the third hot water supply operation is performed in the fourth hot water storage state or the second hot water storage state, the high-temperature water in the tank (30) is also supplied to the hot water supply target (T).

[0142] The third hot water supply operation is performed when the demand of the hot water supply target (T) can be met by the amount of heat (Qa) stored in the tank (30) and the required amount of heat (Qd) of the hot water supply target (T) is greater than that of the second hot water supply operation.

[0143] More specifically, when the demand determination unit (29) determines that the stored heat amount (Qa) is equal to or greater than the required heat amount (Qd) and that the required heat amount (Qd) is equal to or greater than the above-mentioned threshold value (Qs), the controller (25) executes the third hot water supply operation.

[0144] As described above, the demand determination unit (29) determines whether to perform the first hot water supply operation, the second hot water supply operation, or the third hot water supply operation, based on the required heat quantity (Qd) of the hot water supply target (T) and the amount of heat stored (Qa) in the tank (30).

[0145] In the third hot water supply operation, the pump (21) is turned ON, the first three-way valve (51) is in the second state, and the second three-way valve (52) is in the second state. The first mixing valve (53) opens the outlet end of the outlet pipe (42) and the outlet end of the bypass flow path (61). The second mixing valve (54) opens at least the outlet end of the first water supply path (63).

[0146] When the pump (21) is operated, low-temperature water in the low-temperature layer (L) in the tank (30) flows out into the second heating pipe (44). At this time, low-temperature water from the water source (S) is appropriately supplied to the lower reservoir (34) of the tank (30) through the inlet pipe (41). The low-temperature water in the second heating pipe (44) flows through the water flow path (13b) of the water heat exchanger (13) and is heated to medium-temperature water. In the third hot water supply operation, the outlet temperature (To) is controlled to approach the above-mentioned second target temperature (To2) (second temperature).

[0147] The medium-temperature water heated to the second target temperature (To2) in the water heat exchanger (13) is sent to at least the bypass flow path (61).

[0148] Meanwhile, high-temperature water in the high-temperature layer (H) in the tank (30) is sent to the outlet pipe (42). The medium-temperature water in the bypass passage (61) and the high-temperature water in the outlet pipe (42) are mixed in the first mixing valve (53). The water mixed in the first mixing valve (53) flows sequentially through the first water supply passage (63) and the main water supply passage (65), and is supplied to the target of hot water supply (T).

[0149] 9, when a portion of the medium-temperature water heated in the water heat exchanger (13) is supplied to the bypass flow path (61), the remaining medium-temperature water is returned to the intermediate storage section (35) of the tank (30) through the branch flow path (62) and the second return pipe (46). Thus, the medium-temperature water can be stored in the tank (30) while being supplied to the hot water supply target (T).

[0150] On the other hand, when all of the medium-temperature water heated in the water heat exchanger (13) is supplied to the bypass flow path (61), no medium-temperature water is supplied to the intermediate storage portion (35). In this manner, in the third hot water supply operation, the surplus medium-temperature water that does not flow through the bypass flow path (61) out of the medium-temperature water heated in the water heat exchanger (13) is returned to the tank (30).

[0151] The third hot water supply operation is also executed when a signal indicating a demand for hot water supply target (T) is input to the input unit (26) during the second hot water storage operation (see FIG. 5). The second hot water storage operation is an operation in which low-temperature water is heated to medium-temperature water in the water heat exchanger (13). Therefore, during the second hot water storage operation, the second hot water storage operation can be switched to the third hot water supply operation by adjusting the aperture of the first mixing valve (53) and sending medium-temperature water to the bypass flow path (61). Therefore, it is possible to switch from the second hot water storage operation to the third hot water supply operation without significantly changing the flow of water in the hot water supply flow path (40).

[0152] As described above, the third hot water supply operation includes an operation of heating the low-temperature water in the low-temperature layer (L) of the tank (30) to medium-temperature water by the water heat exchanger (13) and supplying the heated medium-temperature water to the target of hot water supply (T). This makes it possible to reduce the temperature difference between the water at the inlet and outlet of the water heat exchanger (13), and to supply a sufficient amount of medium-temperature water to the target of hot water supply (T). In addition, it is possible to suppress an increase in the size of the water heat exchanger (13) and an increase in the heating capacity of the heat source device (10).

[0153] In the third hot water supply operation, the COP of the heat source device (10) can be further improved as compared to the first hot water supply operation. This is because, according to trial calculation results, the COP (C2 described above) when low-temperature water is heated to medium-temperature water in the water heat exchanger (13) is higher than the COPs (C1, C3, and C4) under the other conditions described above. Thus, in the third hot water supply operation, a greater improvement in COP can be obtained as compared to the first hot water supply operation.

[0154] In the second hot water storage operation described above, the low-temperature water is heated to medium-temperature water in the water heat exchanger (13). Thus, in the second hot water storage operation, as in the third hot water supply operation, a large improvement in COP can be obtained.

[0155] As described above, the third hot water supply operation is performed when the heat storage amount (Qa) in the tank (30) can satisfy the heat quantity (Qd) required by the hot water supply target (T). In contrast, the first hot water supply operation is performed when the heat storage amount (Qa) in the tank (30) alone cannot satisfy the heat quantity (Qd) required by the hot water supply target (T). In this manner, the first hot water supply operation is performed only when there is a large demand for hot water from the hot water supply target (T). Therefore, in the normal operation of the hot water supply unit (1), the proportion of the execution time of the third hot water supply operation is greater than the proportion of the execution time of the first hot water supply operation. Since the COP (C2) of the third hot water supply operation is even higher than the average COP (C4) of the two-stage heating associated with the first hot water supply operation, the proportion of the execution time of the third hot water supply operation is increased, thereby improving the energy saving performance of the hot water supply unit (1). On the other hand, when there is a large demand for hot water from the hot water supply target (T), such a large demand for hot water can be quickly met by performing the first hot water supply operation.

[0156] [4th hot water supply operation] The fourth hot water supply operation shown in Fig. 10 is an operation in which low-temperature water in the tank (30) is heated to high-temperature water and the heated high-temperature water is supplied to the hot water supply target (T). The fourth hot water supply operation is executed when a signal indicating a demand for hot water from the hot water supply target (T) is input to the input unit (26) in the above-described first hot water storage operation (see Fig. 4). Thus, the fourth hot water supply operation is basically executed when the tank (30) is in the first hot water storage state (see Fig. 3).

[0157] More specifically, when the temperature determination unit (28) determines that the tank (30) is in the first hot water storage state and a signal indicating demand for the hot water supply target (T) is input to the input unit (26), the controller (25) executes the fourth hot water supply operation. In other words, when there is demand for the hot water supply target (T) when there is a shortage of water in the high temperature layer (H) and the medium temperature layer (M) of the tank (30), the controller (25) executes the fourth hot water supply operation.

[0158] In the fourth hot water supply operation, the pump (21) is turned on, the first three-way valve (51) is in the second state, and the second three-way valve (52) is in the first state. The first mixing valve (53) closes the outlet end of the outlet pipe (42) and opens the outlet end of the bypass flow path (61). The second mixing valve (54) opens at least the outlet end of the first water supply passage (63).

[0159] When the pump (21) is operated, low-temperature water in the low-temperature layer (L) in the tank (30) flows out into the second heating pipe (44). At this time, low-temperature water from the water source (S) is appropriately supplied to the lower reservoir (34) of the tank (30) through the inlet pipe (41). The low-temperature water in the second heating pipe (44) flows through the water flow path (13b) of the water heat exchanger (13) and is heated to high-temperature water. In the fourth hot water supply operation, the outlet temperature (To) is controlled to approach the above-mentioned first target temperature (To1) (first temperature).

[0160] The high-temperature water heated to the first target temperature (To1) in the water heat exchanger (13) is sent to at least the bypass passage (61).

[0161] In the fourth hot water supply operation, the high temperature layer (H) and the medium temperature layer (M) are not formed in the tank (30). Therefore, hot water is not sent from the outflow pipe (42) to the first water supply passage (63). In the fourth hot water supply operation, only the high temperature water flowing through the bypass passage (61) is supplied to the hot water supply target (T).

[0162] 10, when a portion of the high-temperature water heated in the water heat exchanger (13) is supplied to the bypass flow path (61), the remaining high-temperature water is returned to the upper storage section (36) of the tank (30) through the branch flow path (62) and the first return pipe (45). Thus, the high-temperature water can be stored in the tank (30) while being supplied to the hot water supply target (T).

[0163] On the other hand, when all of the high-temperature water heated in the water heat exchanger (13) is supplied to the bypass flow path (61), no high-temperature water is supplied to the upper reservoir (36). In this manner, in the fourth hot water supply operation, the surplus high-temperature water heated in the water heat exchanger (13) that does not flow through the bypass flow path (61) is returned to the tank (30).

[0164] The first hot water storage operation is an operation in which low-temperature water is heated to high-temperature water in the water heat exchanger (13). In the first hot water storage operation, the opening of the first mixing valve (53) is adjusted to send high-temperature water to the bypass flow path (61), thereby making it possible to transition from the first hot water storage operation to the fourth hot water supply operation. Thus, it is possible to transition from the first hot water storage operation to the fourth hot water supply operation without significantly changing the flow of water in the hot water supply flow path (40).

[0165] -Effects of the embodiment- In an embodiment, the hot water supply device (20) includes a hot water supply flow path (40) having a water heat exchanger (13) that heats water and a tank (30) that stores the water heated by the water heat exchanger (13). The hot water supply flow path (40) is configured to perform a first hot water supply operation in which, in a fourth hot water storage state in which a low temperature layer (L), a medium temperature layer (M), and a high temperature layer (H) are formed inside the tank (30), the water heat exchanger (13) heats water in the medium temperature layer (M) to a first temperature (first target temperature (To1)) and supplies it to a hot water supply target (T).

[0166] In the first hot water supply operation, since the temperature difference between the water at the inlet and the outlet of the water heat exchanger (13) is relatively small, high-temperature water can be obtained without reducing the flow rate of water flowing through the water heat exchanger (13). Therefore, a sufficient amount of high-temperature water can be supplied to the hot water supply target (T). In other words, a sufficient amount of high-temperature water can be supplied to the hot water supply target (T) without increasing the capacity of the water heat exchanger (13) or increasing the size of the water heat exchanger (13).

[0167] In the first hot water supply operation, the medium-temperature water produced in the hot water storage operation is further heated to obtain high-temperature water. As described above, in such two-stage heating, the COP of the heat source device (10) can be improved compared to the case where low-temperature water is heated to high-temperature water. Therefore, the energy saving of the hot water supply device (20) can be improved.

[0168] In the embodiment, the first hot water supply operation includes an operation of supplying water heated to a first temperature (first target temperature (To1)) in the water heat exchanger (13) to the hot water supply target (T) by bypassing the tank (30).

[0169] When high-temperature water heated in the water heat exchanger (13) is supplied to the tank (30), heat radiation loss increases. Specifically, heat of the high-temperature water in the tank (30) is released to the outside of the tank (30), or the heat of the high-temperature water is transferred to medium-temperature water or low-temperature water. In the embodiment, at least a part of the high-temperature water heated in the water heat exchanger (13) bypasses the tank (30), so that such heat radiation loss can be suppressed.

[0170] In this embodiment, the first hot water supply operation includes an operation of supplying water heated to a first temperature (first target temperature (To1)) in the water heat exchanger (13) to the hot water supply target (T) via the high temperature layer (H) in the tank (30).

[0171] In this operation, by returning high-temperature water to the tank (30), it is possible to supply high-temperature water to the hot water supply target (T) and store the high-temperature water in the tank (30) at the same time. In addition, in this operation, high-temperature water is preferentially caused to flow through the bypass flow path (61). When excess high-temperature water is generated, the excess high-temperature water is sent to the high-temperature layer (H) of the tank (30) through the first return pipe (45). This makes it possible to minimize heat radiation loss.

[0172] In an embodiment, the first hot water supply operation includes an operation of supplying at least a portion of the water heated in the water heat exchanger (13) to the hot water supply target (T) by bypassing the tank (30), and simultaneously supplying water from the high temperature layer (H) of the tank (30) to the hot water supply target (T).

[0173] In this operation, the high-temperature water flowing through the bypass flow path (61) and the high-temperature water flowing out of the tank (30) are mixed and supplied to the target of hot water supply (T), so that a sufficient amount of high-temperature water can be supplied to the target of hot water supply (T). In addition, by causing the high-temperature water in the tank (30) to flow out to the outside, the heat radiation loss of this high-temperature water can be suppressed.

[0174] In this embodiment, an upper storage section (36) corresponding to the high temperature layer (H), a second storage section (34) corresponding to the low temperature layer (L), and an intermediate storage section (35) corresponding to the medium temperature layer (M) are formed inside the tank (30). The hot water supply flow path (40) includes an inlet pipe (41) communicating between the water source (S) and the lower storage section (34), an outlet pipe (42) communicating with the upper storage section (36), and an intermediate storage section (35). the first heating pipe (43) communicating with the inlet side of the water heat exchanger (13), a bypass pipe (61) communicating with the outlet side of the water heat exchanger (13) and the outlet end of the outlet pipe (42), a first return pipe (45) communicating with the outlet side of the water heat exchanger (13) and the upper reservoir (36), and a first mixing valve (53) adjusting at least the flow rates of the outlet pipe (42) and the bypass flow path (61).

[0175] With this configuration, a first hot water supply operation can be realized. In the first hot water supply operation, the flow rate of water in the bypass flow path (61) and the flow rate of water in the outflow pipe (42) can be adjusted by adjusting the first mixing valve (53). The outflow end of the bypass flow path (61) can be opened or closed, and the outflow end of the outflow pipe (42) can be opened or closed. By adjusting the flow rate of water in the bypass flow path (61), the flow rate of water in the first return pipe (45) can be indirectly adjusted. By adjusting the flow rate of water in the bypass flow path (61), the flow rate of water flowing through the water heat exchanger (13) can be indirectly adjusted. By adjusting the flow rate of water flowing through the water heat exchanger (13), the temperature of the water flowing out of the water heat exchanger (13) (outlet temperature (To)) can be adjusted.

[0176] In the embodiment, the hot water supply flow path (40) includes a second return pipe (46) that connects the outlet side of the water heat exchanger (13) with the intermediate storage section (35), a second heating pipe (44) that connects the lower storage section (34) with the inlet side of the water heat exchanger (13), a first three-way valve (51) that switches between a communication state between the inlet side of the water heat exchanger (13) and one of the first heating pipe (43) and the second heating pipe (44), and a second three-way valve (52) that switches between a communication state between the outlet side of the water heat exchanger (13) and one of the first return pipe (45) and the second return pipe (46).

[0177] With this configuration, the first hot water supply operation, the second hot water supply operation, the third hot water supply operation, and the fourth hot water supply operation can be switched and executed. In addition, the first hot water storage operation, the second hot water storage operation, and the third hot water storage operation can be switched and executed.

[0178] In the embodiment, the hot water supply flow path (40) is configured to perform a second hot water supply operation in which water from the medium temperature layer (M) of the intermediate storage section (35) is supplied to the hot water supply target (T) via the second return pipe (46) and the bypass flow path (61), while simultaneously supplying water from the high temperature layer (H) of the tank (30) to the hot water supply target (T).

[0179] In the second hot water supply operation, medium temperature water can be supplied to the hot water supply target (T) while the heat source device (10) is stopped. In the second hot water supply operation, as shown in Fig. 8, medium temperature water is supplied to the hot water supply target (T) through the second return pipe (46) and the bypass flow path (61). The second return pipe (46) also serves as a flow path for sending medium temperature water to the tank (30) in the heating section (13) in the second hot water storage operation and the third hot water supply operation. This allows the number of pipes in the hot water supply flow path (40) to be reduced.

[0180] In the embodiment, the hot water supply flow path (40) is configured to perform a third hot water supply operation in which water in the low temperature layer (L) of the second storage section (34) is heated to a second temperature lower than the first temperature by the heating section (13) and supplied to the hot water supply target (T), and at the same time, water in the high temperature layer (H) of the tank (30) is supplied to the hot water supply target (T).

[0181] In the third hot water supply operation, when the tank (30) is in the second hot water storage state or the fourth hot water storage state, medium-temperature water can be supplied to the hot water supply target (T). When low-temperature water is heated to medium-temperature water in the heating section (13), the COP of the heat source device (10) can be improved as described above.

[0182] In this embodiment, the third hot water supply operation includes an operation of returning a part of the water heated in the heating section (13) to the medium temperature layer (M) of the intermediate storage section (35).

[0183] In this operation, medium-temperature water can be stored in the tank (30) while medium-temperature water is being supplied to the target (T) for hot water supply.

[0184] In this embodiment, a demand determination unit (29) is provided which determines whether the first hot water supply operation or the third hot water supply operation is to be performed, based on the amount of heat required by the hot water supply target (T) and the amount of heat stored in the tank (30).

[0185] Specifically, when the demand determination unit (29) determines that the amount of stored heat (Qa) is lower than the amount of required heat (Qd), the demand determination unit (29) executes a first hot water supply operation. In the first hot water supply operation, medium-temperature water is heated to high-temperature water by the heating unit (13), so that even if the amount of stored heat (Qa) in the tank (30) is insufficient, sufficient high-temperature water can be supplied to the hot water supply target (T).

[0186] When the demand determination unit (29) determines that the amount of stored heat (Qa) is equal to or greater than the required amount of heat (Qd), it executes the third hot water supply operation, thereby enabling an operation with a high COP to be executed while satisfying the demand of the hot water supply target (T).

[0187] In the embodiment, the hot water supply flow path (40) is configured to perform a fourth hot water supply operation in which water in the low temperature layer (L) of the second storage section (34) is heated to a first temperature by the heating section (13) and supplied to the hot water supply target (T).

[0188] In the fourth hot water supply operation, high-temperature water can be supplied to the hot water supply target (T) in a situation where there is no high-temperature water in the tank (30).

[0189] -Modifications of the embodiment- In the modification shown in FIG. 11, a second water supply passage (64), a third water supply passage (66), and a third mixing valve (55) are added to the hot water supply flow path (40) of the above embodiment.

[0190] The second water supply passage (64) communicates between the intermediate storage section (35) of the tank (30) and the inflow end of the main water supply passage (65). One end of the second water supply passage (64) is connected to the intermediate storage section (35) of the tank (30). The other end of the second water supply passage (64) is connected to the second mixing valve (54). The second water supply passage (64) is composed of a tank side water supply passage (64a) on the upstream side thereof and a hot water supply side water supply passage (64b) on the downstream side thereof. The outflow end of the tank side water supply passage (64a) and the inflow end of the hot water supply side water supply passage (64b) are connected to the third mixing valve (55).

[0191] The third water supply passage (66) connects the inflow pipe (41) and the second water supply passage (64). The outlet end of the third water supply passage (66) is connected to the third mixing valve (55).

[0192] In a modified example, the second mixing valve (54) corresponds to the second adjustment mechanism. The second mixing valve (54) adjusts the flow rate of both the first water supply passage (63) and the second water supply passage (64). The second mixing valve (54) may be configured to adjust only the flow rate of the second water supply passage (64).

[0193] The third mixing valve (55) corresponds to the third adjustment mechanism. The third mixing valve (55) adjusts the flow rate of both the second water supply passage (64) and the third water supply passage (66). The third mixing valve (55) may be configured to adjust the flow rate of only the third water supply passage (66). The third mixing valve (55) opens and closes the outflow end of the tank side water supply passage (64a) and the outflow end of the third water supply passage (66).

[0194] -Hot water operation- The hot water supply operation of the modified example is basically the same as that of the above-described embodiment. In the first, second, and third hot water supply operations of the modified example, the medium-temperature water in the medium-temperature layer (M) of the intermediate storage section (35) of the tank (30) can be supplied to the hot water supply target (T) via the second water supply passage (64). At this time, the low-temperature water of the water source (S) can be supplied to the second water supply passage (64) via the third water supply passage (66). In this case, the medium-temperature water and the low-temperature water are mixed in the third mixing valve (55).

[0195] In the first hot water supply operation shown in FIG. 12, the medium-temperature water in the medium temperature layer (M) is heated to high temperature water by the heating section (13). Therefore, in the first hot water supply operation (see FIG. 7) of the above-mentioned embodiment, the medium-temperature water cannot be directly supplied to the hot water supply target (T). In contrast, in the first hot water supply operation of the modified example, the medium-temperature water in the medium temperature layer (M) can be heated to high temperature water by the water heat exchanger (13) and supplied to the hot water supply target (T) via the second water supply passage (64). In the modified example, the mixing ratio of the high temperature water, the medium temperature water, and the low temperature water can be substantially adjusted by adjusting the opening degree of the second mixing valve (54) and the third mixing valve (55). Therefore, it is possible to finely adjust the temperature of the water to be supplied to the hot water supply target (T).

[0196] Other Embodiments In the above-described embodiment and modified examples, the following configurations may be adopted.

[0197] Three or more temperature sensors may be provided in the tank (30). The state of hot water stored in the tank (30) may be determined based on the difference between the detected values ​​of the temperature sensors.

[0198] At least one of the first adjustment mechanism (53), the second adjustment mechanism (54), and the third adjustment mechanism (55) does not have to be a mixing valve. Instead of these adjustment mechanisms (53, 54, 55), a flow rate adjustment valve, a solenoid opening / closing valve, a three-way valve, or the like may be combined.

[0199] The water heating apparatus (20) may be configured to perform at least the first hot water supply operation among the first, second, third, and fourth hot water supply operations. When the water heating apparatus (20) is configured to perform only the first and third hot water supply operations among these hot water supply operations, it is preferable to provide a determination unit (29) that determines whether the first or third hot water supply operation is to be performed based on the heat required by the hot water supply target (T) and the heat storage amount of the tank (30). When the water heating apparatus (20) is configured to perform only the first, second, and third hot water supply operations among these hot water supply operations, it is preferable to provide a determination unit (29) that determines whether the first, second, or third hot water supply operation is to be performed based on the heat required by the hot water supply target (T) and the heat storage amount of the tank (30).

[0200] The heating section for heating the water may be another means such as a heater. 2 The refrigerant may be a supercritical cycle in which the high pressure of the refrigerant is equal to or higher than the critical pressure.

[0201] Although the embodiments and modifications have been described above, it will be understood that various modifications of form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be appropriately combined or substituted as long as the functions of the subject matter of this disclosure are not impaired. The descriptions "first," "second," "third," etc. described above are used to distinguish the words to which these descriptions are attached, and do not limit the number or order of the words. [Industrial Applicability]

[0202] The present disclosure is useful for water heating devices. [Explanation of symbols]

[0203] 10. Hot water supply equipment 13 Water heat exchanger (heating part) 25 Controller 29 Judgment Department (Demand Judgment Department) 30 Tank 34 Second Reservoir 35 Intermediate storage section 36 First Reservoir 40 Hot water supply flow path 41 Inlet pipe (inlet flow path) 42 Outlet pipe (outlet flow path) 43 First heating pipe (first heating flow path) 44 Second heating pipe (second heating flow path) 45 First return pipe (first return flow path) 46 Second return pipe (second return flow path) 51 First switching mechanism (first three-way valve) 52 Second switching mechanism (second three-way valve) 53 First adjustment mechanism (first mixing valve) 54 Second adjustment mechanism (second mixing valve) 55 Third adjustment mechanism (third mixing valve) 61 Bypass pipe (bypass flow path) 63 1st water supply channel 64 2nd water supply channel 65 Main water supply channel 66 Third water supply channel

Claims

1. A hot water supply device including a hot water supply flow path (40) having a heating section (13) that heats water and a tank (30) that stores the water heated by the heating section (13), The hot water supply flow path (40) is configured to perform a first hot water supply operation in which, in a hot water storage state in which a low temperature layer (L), a medium temperature layer (M), and a high temperature layer (H) are formed inside the tank (30), water in the medium temperature layer (M) is heated to a first temperature by the heating section (13) and supplied to a hot water supply target (T).

2. In claim 1, The hot water supply device is characterized in that the first hot water supply operation includes an operation of supplying water heated to the first temperature in the heating section (13) to the hot water supply target (T) by bypassing the tank (30).

3. In claim 1, The hot water supply device is characterized in that the first hot water supply operation includes an operation of supplying water heated to the first temperature in the heating section (13) to the hot water supply target (T) via a high temperature layer (H) in the tank (30).

4. In claim 1 or 2, The hot water supply device is characterized in that the first hot water supply operation includes an operation of supplying at least a portion of the water heated in the heating section (13) to the hot water supply target (T) by bypassing the tank (30), while simultaneously supplying water from a high temperature layer (H) of the tank (30) to the hot water supply target (T).

5. In any one of claims 1 to 4, A first storage section (36) corresponding to the high temperature layer (H), a second storage section (34) corresponding to the low temperature layer (L), and an intermediate storage section (35) corresponding to the medium temperature layer (M) are formed inside the tank (30), The hot water supply passage (40) an inflow passage (41) communicating between a water source (S) and the second storage section (34); an outflow passage (42) communicating with the first storage portion (36); a first heating flow path (43) communicating between the intermediate reservoir (35) and an inlet side of the heating section (13); a bypass flow path (61) communicating an outlet side of the heating section (13) with an outlet end of the outlet flow path (42); a first return flow path (45) communicating an outlet side of the heating section (13) with the first storage section (36); a first adjustment mechanism (53) for adjusting at least the flow rate of each of the outflow passage (42) and the bypass passage (61).

6. In claim 5, The hot water supply passage (40) a second return flow path (46) communicating an outlet side of the heating section (13) with the intermediate storage section (35); a second heating flow path (44) communicating the second storage portion (34) with an inlet side of the heating portion (13); a first switching mechanism (51) that switches between a communication state between an inlet side of the heating section (13) and one of the first heating flow path (43) and the second heating flow path (44); a second switching mechanism (52) that switches between a communication state of an outlet side of the heating section (13) and one of the first return flow path (45) and the second return flow path (46).

7. In claim 6, The hot water supply flow path (40) is configured to supply water from the medium temperature layer (M) of the intermediate storage section (35) to the hot water supply target (T) via the second return flow path (46) and the bypass flow path (61), while simultaneously performing a second hot water supply operation to supply water from the high temperature layer (H) of the tank (30) to the hot water supply target (T).

8. In claim 6 or 7, The hot water supply flow path (40) is configured to perform a third hot water supply operation in which water in the low temperature layer (L) of the second storage section (34) is heated to a second temperature lower than the first temperature by the heating section (13) and supplied to a hot water supply target (T), while simultaneously supplying water from the high temperature layer (H) of the tank (30) to the hot water supply target (T).

9. In claim 8, The hot water supply apparatus, wherein the third hot water supply operation includes an operation of returning a part of the water heated in the heating section (13) to the intermediate temperature layer (M) of the intermediate storage section (35).

10. In claim 8 or 9, A hot water supply device characterized by having a judgment unit (29) that judges whether the first hot water supply operation or the third hot water supply operation will be performed based on the heat required by the hot water supply target (T) and the heat storage amount in the tank (30).

11. In claim 10, the hot water supply flow path (40) is configured to perform a second hot water supply operation in which water from the medium temperature layer (M) of the intermediate storage portion (35) is supplied to a hot water supply target (T) through the second return flow path (46) and the bypass flow path (61) and, at the same time, water from the high temperature layer (H) of the tank (30) is supplied to the hot water supply target (T); The hot water supply device is characterized in that the determination unit (29) determines whether to perform the first hot water supply operation, the second hot water supply operation, or the third hot water supply operation based on the heat required by the hot water supply target (T) and the heat stored in the tank (30).

12. In any one of claims 5 to 11, The hot water supply flow path (40) is configured to perform a fourth hot water supply operation in which water in the low temperature layer (L) of the second storage section (34) is heated to the first temperature in the heating section (13) and supplied to a hot water supply target (T).

13. In claim 12, a control device (25) that executes the fourth hot water supply operation when there is a demand for the hot water supply target (T) in a state in which there is a shortage of water in the high temperature layer (H) and the medium temperature layer (M) of the tank (30). A water heating apparatus characterized by the above.

14. In any one of claims 5 to 13, The hot water supply passage (40) a first water supply passage (63) communicating with an outlet end of the outlet flow passage (42); a main water supply passage (65) communicating between the first water supply passage (63) and the target of hot water supply (T); a second water supply passage (64) communicating the intermediate storage section (35) with an inlet end of the main water supply passage (65); and a second adjustment mechanism (54) that adjusts at least the flow rate of the second water supply passage (64) out of the flow rate of the first water supply passage (63) and the flow rate of the second water supply passage (64).

15. In claim 14, The hot water supply passage (40) a third water supply passage (66) communicating with the inflow passage (41) and the second water supply passage (64); and a third adjustment mechanism (55) that adjusts at least the flow rate of the third water supply passage (66) out of the flow rate of the second water supply passage (64) and the flow rate of the third water supply passage (66).

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