Hot water supply unit

Abstract

A hot water supply unit includes a refrigerant unit (U) having a refrigerant circuit (R1) configured to perform a refrigeration cycle by using a first refrigerant that is a flammable refrigerant. The refrigerant circuit (R1) has a compressor (21), a first heat exchanger (23) configured to exchange heat between the first refrigerant in the refrigerant circuit (R1) and water in a water circuit (W), a decompression mechanism (24), and a second heat exchanger (22) configured to exchange heat between the first refrigerant in the refrigerant circuit (R1) and a heating medium in a heating medium circuit (R2, 100). The refrigerant unit (U) is disposed above the tank (41).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a hot water supply unit.BACKGROUND ART

[0002] Patent Document 1 discloses a hot water supply unit. The hot water supply unit includes a refrigerant circuit having a first heat exchanger and a second heat exchanger and also a tank for hot water supply. The tank stores water heated by a refrigerant in the refrigerant circuit.CITATION LISTPATENT DOCUMENT

[0003] Patent Document 1: Japanese Unexamined Patent Publication No. 2004-132647SUMMARY OF THE INVENTIONTECHNICAL PROBLEM

[0004] The inventors of this application have invented a hot water supply unit having a casing that houses a tank and a refrigerant unit having a refrigerant circuit. The hot water supply unit (the casing) is disposed in an indoor space. The refrigerant circuit employs a flammable refrigerant as a refrigerant. The hot water supply unit is used for hot water supply or air conditioning, for example. Meanwhile, when the hot water supply unit is disposed in the indoor space as described above, there is a greater risk that the flammable refrigerant may leak.

[0005] An object of the present disclosure is to reduce the risk that a flammable refrigerant may leak.SOLUTION TO THE PROBLEM

[0006] A first aspect is directed to a hot water supply unit. The hot water supply unit includes: a refrigerant unit (U) having a refrigerant circuit (R1) configured to perform a refrigeration cycle by using a first refrigerant that is a flammable refrigerant; a tank (41) configured to store water directly or indirectly heated by the first refrigerant; and a casing (60) housing the refrigerant unit (U) and the tank (41) and disposed in an indoor space (I). The refrigerant circuit (R1) has a compressor (21), a first heat exchanger (23) configured to exchange heat between the first refrigerant in the refrigerant circuit (R1) and water in a water circuit (W), a decompression mechanism (24), and a second heat exchanger (22) configured to exchange heat between the first refrigerant in the refrigerant circuit (R1) and a heating medium in a heating medium circuit (R2, 100). The refrigerant unit (U) is disposed above the tank (41).

[0007] According to the first aspect, the refrigerant unit (U) is disposed above the tank (41), whereby the refrigerant unit (U) is located at a higher position. When a refrigerant leaks from the refrigerant circuit (R1) of the refrigerant unit (U), the flammable refrigerant having a higher specific gravity than air flows downward from the refrigerant unit (U). The refrigerant gradually diffuses in the air before reaching the floor surface of the indoor space (I). Accordingly, it is possible to reduce the concentration of the leaked refrigerant.

[0008] A second aspect is an embodiment of the first aspect. In the second aspect, the casing (60) has a first side surface (63) having a first access opening (A1) of a first space (S1) that houses the refrigerant unit (U), and a second side surface (64) located opposite to the first side surface (63) in the casing (60). The hot water supply unit further includes the support (70) that supports the refrigerant unit (U) and that can be loaded and unloaded through the first access opening (A1).

[0009] According to the second aspect, by moving the support (70) to the outside of the casing (60) through the first access opening (A1), it is possible to unload the refrigerant unit (U) to the outside of the casing (60). Accordingly, the operator can perform a predetermined operation while the refrigerant unit (U) is unloaded to the outdoor space, and thus it is possible to reduce the risk that the first refrigerant, a flammable refrigerant, may leak.

[0010] A third aspect is an embodiment of the second aspect. In the third aspect, the refrigerant unit (U) has a water-side connecting portion (C1, C2) configured to detachably connect the first heat exchanger (23) and the water circuit (W), and a heating medium-side connecting portion (C3, C4) configured to detachably connect the second heat exchanger (22) and the heating medium circuit (R2, 100).

[0011] According to the third aspect, by disconnecting the water-side connecting portions (C1, C2), it is possible to detach the first heat exchanger (23) from the water circuit (W). By disconnecting the heating medium-side connecting portions (C3, C4), it is possible to detach the second heat exchanger (22) from the heating medium circuit (R2, 100). As a result, the refrigerant unit (U) detached from the water circuit (W) and the heating medium circuit (R2, 100) can be easily unloaded to the outside of the casing (60) through the first access opening (A1).

[0012] A fourth aspect is an embodiment of the third aspect. In the fourth aspect, the refrigerant unit (U) is closer to the first side surface (63) than the water-side connecting portion (C1, C2) and the heating medium-side connecting portion (C3, C4) are.

[0013] According to the fourth aspect, the refrigerant unit (U) is closer to the first side surface (63), whereby the refrigerant unit (U) is less likely to interfere with the water circuit (W) and the heating medium circuit (R2, 100). Accordingly, it is possible to load and unload the refrigerant unit (U) easily.

[0014] A fifth aspect is an embodiment of the fourth aspect. In the fifth aspect, the casing (60) has an upper surface (61) having a second access opening (A2) of the first space (S1).

[0015] According to the fifth aspect, the operator can access the water-side connecting portions (C1, C2) and the heating medium-side connecting portions (C3, C4) from above the casing (60) through the second access opening (A2).

[0016] A sixth aspect is an embodiment of any one of the first to fifth aspects. In the sixth aspect, the hot water supply unit further includes a first outer connecting portion (83, 84, 85, 86) provided on the upper surface (61) of the casing (60) and connected with a water pipe (93, 94, 95, 96) of the water circuit (W) extending from an outside of the casing (60).

[0017] According to the sixth aspect, the refrigerant unit (U) is located above the tank (41). The first outer connecting portions (83, 84, 85, 86) are provided on the upper surface of the casing (60). Accordingly, the distance from the first heat exchanger (23) to the first outer connecting portions (83, 84, 85, 86) is shortened.

[0018] A seventh aspect is an embodiment of the sixth aspect. In the seventh aspect, the casing (60) has a first side surface (63) having a first access opening (A1) of a first space (S1) that houses the refrigerant unit (U), and a second side surface (64) located opposite to the first side surface (63) in the casing (60). The first outer connecting portion (83, 84, 85, 86) is closer to the second side surface (64) than to the first side surface (63).

[0019] An eighth aspect is an embodiment of any one of the first to seventh aspects. In the eighth aspect, the hot water supply unit further includes a second outer connecting portion (81, 82) provided on the upper surface (61) of the casing (60) and connected with a refrigerant pipe (91, 92) of the heating medium circuit (R2, 100) extending from an outside of the casing (60).

[0020] According to the eighth aspect, the refrigerant unit (U) is located above the tank (41). The second outer connecting portions (81, 82) are provided on the upper surface of the casing (60). Accordingly, the distance from the refrigerant heat exchanger (22) to the second outer connecting portions (81, 82) is shortened.

[0021] A ninth aspect is an embodiment of the eighth aspect. In the ninth aspect, the casing (60) has a first side surface (63) having a first access opening (A1) of a first space (S1) that houses the refrigerant unit (U), and a second side surface (64) located opposite to the first side surface (63) in the casing (60). The second outer connecting portion (81, 82) is closer to the second side surface (64) than to the first side surface (63).

[0022] A tenth aspect is an embodiment of any one of the first to ninth aspects. In the tenth aspect, the casing (60) has a communication path (78) that allows the indoor space (I) to communicate with the first space (S1) that houses the refrigerant unit (U).

[0023] According to the tenth aspect, when a refrigerant leaks from the first refrigerant circuit (R1) of the refrigerant unit (U), it is possible to discharge this refrigerant from the first space (S1) to the indoor space (I) located outside the casing (60) through the communication paths (78). As a result, it is possible to accelerate diffusion of the refrigerant outside the casing (60), and thus it is possible to reduce the concentration of the refrigerant.

[0024] An eleventh aspect is an embodiment of the tenth aspect. In the eleventh aspect, the communication path (78) is located at a lower position than the refrigerant unit (U).

[0025] According to the eleventh aspect, the communication paths (78) is formed at a lower position than the refrigerant unit (U), and thus it is easier to guide the refrigerant having leaked from the refrigerant circuit (R1) to the communication path (78). Accordingly, it is possible to accelerate diffusion of the refrigerant outside the casing (60).

[0026] A twelfth aspect is an embodiment of the tenth or eleventh aspect. In the twelfth aspect, the hot water supply unit further includes a refrigerant sensor (79) configured to detect leakage of the first refrigerant. The refrigerant sensor (79) is disposed on the communication path (78) or near the communication path (78).

[0027] According to the twelfth aspect, the refrigerant sensor (79) is disposed on the communication path (78) or near the communication path (78), and thus the refrigerant sensor (79) can detect leakage of a refrigerant immediately.

[0028] A thirteenth aspect is an embodiment of the tenth or eleventh aspect. In the thirteenth aspect, the hot water supply unit further includes an inner casing (70) disposed in the first space (S1) and housing the refrigerant unit (U). The inner casing (70) has an opening (70a) that allows an outside and an inside of the inner casing (70) to communicate with each other.

[0029] According to the thirteenth aspect, the refrigerant having leaked from the refrigerant circuit (R1) can be stored in the inner casing (70). The refrigerant in the inner casing (70) flows out through the opening (70a) and tends to accumulate outside the inner casing (70) in the first space (S1). This refrigerant flows out of casing (60) through the communication path (78). In this manner, it is possible to reduce the speed at which a refrigerant discharges to the outside of the casing (60), and thus it is possible to reduce the concentration of the refrigerant outside the casing (60).

[0030] A fourteenth aspect is an embodiment of the thirteenth aspect. In the fourteenth aspect, the hot water supply unit further includes a refrigerant sensor (79) configured to detect leakage of the first refrigerant. The refrigerant sensor (79) is disposed in the inner casing (70) or near the opening (70a).

[0031] According to the fourteenth aspect, the refrigerant sensor (79) is disposed in the inner casing (70) or near the opening (70a), and thus the refrigerant sensor (79) can detect leakage of a refrigerant immediately.

[0032] A fifteenth aspect is an embodiment of any one of the third to fifth aspects. In the fifteenth aspect, the hot water supply unit further includes a shielding member (98) configured to shield the heating medium-side connecting portion (C3, C4) and the refrigerant circuit (R1) from each other.

[0033] According to the fifteenth aspect, the refrigerant circuit (R1) filled with the first refrigerant that is a flammable refrigerant is shielded from the heating medium-side connecting portions (C3, C4) by the shielding member (98). Accordingly, it is possible to reduce the risk that the first refrigerant may ignite due to connection with the heating medium-side connecting portions (C3, C4).

[0034] A sixteenth aspect is an embodiment of any one of the first to fifteenth aspects. In the sixteenth aspect, the hot water supply unit further includes an electric component unit (71) housed in the casing (60). The electric component unit (71) is disposed above the tank (41).

[0035] According to the sixteenth aspect, if the refrigerant having leaked from the refrigerant circuit (R1) accumulates at the bottom portion of the casing (60), the electric component unit (71) is less affected by the refrigerant accumulated at the bottom portion.

[0036] A seventeenth aspect is an embodiment of any one of the tenth to fourteenth aspects. In the seventeenth aspect, the hot water supply unit further includes an electric component unit (71) housed in the casing (60). The electric component unit (71) is located at a higher position than the communication path (78).

[0037] According to the seventeenth aspect, the electric component unit (71) is less affected by the leaked refrigerant.

[0038] An eighteenth aspect is an embodiment of any one of the first to seventeenth aspects. In the eighteenth aspect, the heating medium circuit (R2, 100) is a second refrigerant circuit (R2) configured to perform a refrigeration cycle by using a second refrigerant.

[0039] According to the eighteenth aspect, the hot water supply unit performs a so-called binary refrigeration cycle.BRIEF DESCRIPTION OF THE DRAWINGS

[0040] [FIG. 1] FIG. 1 is a piping system diagram of a hot water supply system according to an embodiment. [FIG. 2] FIG. 2 is a perspective view of the appearance of a hot water supply unit. [FIG. 3] FIG. 3 is a schematic plan view of the layout of components in a first space. [FIG. 4] FIG. 4 is a top view of a top plate. [FIG. 5] FIG. 5 is a vertical sectional view of an internal structure of the first space in a casing. [FIG. 6] FIG. 6 is a vertical sectional view of an internal structure of a first space in a casing of a hot water supply unit according to a first variation. [FIG. 7] FIG. 7 is a vertical sectional view of an internal structure of a first space in a casing of a hot water supply unit according to a second variation. [FIG. 8] FIG. 8 is a schematic plan view of the layout of components in a first space in a hot water supply unit according to a third variation. [FIG. 9] FIG. 9 is a piping system diagram of a hot water supply system according to a fourth variation. DESCRIPTION OF EMBODIMENTS

[0041] Embodiments of the present disclosure will be described in detail below with reference to the drawings. The present disclosure is not limited to the embodiments shown below, and various changes can be made within the scope without departing from the technical concept of the present disclosure. Since each of the drawings is intended to illustrate the present disclosure conceptually, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.(1) Configuration of Hot Water Supply System(1-1) General Configuration

[0042] A hot water supply system (1) supplies hot water to a target. The target of this embodiment includes a target of hot water supply, such as a faucet, a shower, or a bathtub, and also a heating device (5) using hot water. The hot water supply system (1) is connected to the target of hot water supply and the heating device (5) via water pipes. The hot water supply system (1) has an outdoor unit (10) disposed outdoors and a hot water supply unit (20) disposed indoors.

[0043] As a circuit configuration, the hot water supply system (1) includes a first refrigerant circuit (R1), a second refrigerant circuit (R2), and a water circuit (W). The first refrigerant circuit (R1) is filled with a flammable refrigerant as a first refrigerant. The second refrigerant circuit (R2) is filled with carbon dioxide as a second refrigerant. The second refrigerant circuit (R2) is an example of a heating medium circuit, and carbon dioxide is an example of a heating medium.

[0044] The first refrigerant is propane (R290), a natural refrigerant that is highly flammable. The natural refrigerant is a refrigerant which has an ozone depletion potential of zero and a low global warming potential and thus which has less impact on the environment. Propane ignites at 500°C or less. The flammable refrigerant may be methane (R50), ethane (R170), butane (R600), or isobutane (R600a). The flammable refrigerant may be not a refrigerant that is highly flammable but a refrigerant that is slightly flammable. The slightly flammable refrigerant may be difluoromethane (R32) or tetrafluoropropene (HFO-1234yf). The first refrigerant may be a single component refrigerant comprised of one of the above refrigerants, or may be a mixed refrigerant comprised of one of the above refrigerants and another one or more of the above refrigerants.

[0045] The hot water supply system (1) has a refrigerant heat exchanger (22), a first water heat exchanger (23), and a second water heat exchanger (26). The refrigerant heat exchanger (22) is shared by the first refrigerant circuit (R1) and the second refrigerant circuit (R2), the first water heat exchanger (23) is shared by the first refrigerant circuit (R1) and the water circuit (W), and the second water heat exchanger (26) is shared by the second refrigerant circuit (R2) and the water circuit (W). The refrigerant heat exchanger (22) is an example of the first heat exchanger, and the first water heat exchanger (23) is an example of the second heat exchanger. The hot water supply system (1) performs a so-called binary refrigeration cycle by using the first refrigerant circuit (R1) and the second refrigerant circuit (R2).(1-2) Outdoor Unit

[0046] The outdoor unit (10) includes part of the second refrigerant circuit (R2). The outdoor unit (10) has a second compressor (11), an outdoor heat exchanger (12), a second expansion valve (13), a four-way switching valve (14), and a second accumulator (15) as components of the second refrigerant circuit (R2). The outdoor unit (10) has an outdoor fan (16). The second compressor (11) compresses a sucked refrigerant and discharges a compressed refrigerant. The outdoor heat exchanger (12) exchanges heat between the outdoor air transported by the outdoor fan (16) and the second refrigerant. The second expansion valve (13) decompresses a refrigerant. The four-way switching valve (14) switches between a first state indicated by the solid lines in FIG. 1 and a second state indicated by the broken lines in FIG. 1. The second accumulator (15) stores a liquid refrigerant that is to be sucked into the second compressor (11).(1-3) Circuit Configuration of Hot Water Supply Unit

[0047] The hot water supply unit (30) includes the entire part of the first refrigerant circuit (R1). The hot water supply unit (20) has a first compressor (21), the refrigerant heat exchanger (22), the first water heat exchanger (23), a first expansion valve (24), and a first accumulator (25) as components of the first refrigerant circuit (R1). The first compressor (21) compresses a sucked refrigerant and discharges a compressed refrigerant. The refrigerant heat exchanger (22) has a first flow path (P1) connected to the first refrigerant circuit (R1) and a second flow path (P2) connected to the second refrigerant circuit (R2). The refrigerant heat exchanger (22) exchanges heat between the first refrigerant in the first flow path (P1) of the first refrigerant circuit (R1) and the second refrigerant in the second flow path (P2) of the second refrigerant circuit (R2). The first water heat exchanger (23) has a third flow path (P3) connected to the first refrigerant circuit (R1) and a fourth flow path (P4) connected to the water circuit (W). The first water heat exchanger (23) exchanges heat between the first refrigerant in the third flow path (P3) of the first refrigerant circuit (R1) and the water in the fourth flow path (P4) of the water circuit (W). The first expansion valve (24) is an example of a decompression mechanism that decompresses a refrigerant. The first accumulator (25) stores a liquid refrigerant that is to be sucked into the first compressor (21). The refrigerant heat exchanger (22) and the first water heat exchanger (23) are configured as plate heat exchangers, for example.

[0048] The hot water supply unit (20) includes part of the second refrigerant circuit (R2). The hot water supply unit (20) has the first water heat exchanger (23) described above and also the second water heat exchanger (26) as components of the second refrigerant circuit (R2). The second water heat exchanger (26) has a fifth flow path (P5) connected to the second refrigerant circuit (R2) and a sixth flow path (P6) connected to the water circuit (W). The second water heat exchanger (26) exchanges heat between the second refrigerant in the fifth flow path (P5) of the second refrigerant circuit (R2) and the water in the sixth flow path (P6) of the water circuit (W). The second water heat exchanger (26) is configured as a plate heat exchanger, for example.

[0049] The hot water supply unit (20) has a first pipe (31), a second pipe (32), a third pipe (33), and a bypass pipe (34) as refrigerant pipes that form the second refrigerant circuit (R2). One end of the first pipe (31) is connected to a gas-side line of the second refrigerant circuit (R2). The other end of the first pipe (31) is connected to one end of the fifth flow path (P5) of the second water heat exchanger (26). One end of the second pipe (32) is connected to the other end of the fifth flow path (P5) of the second water heat exchanger (26). The other end of the second pipe (32) is connected to one end of the second flow path (P2) of the refrigerant heat exchanger (22). One end of the third pipe (33) is connected to the other end of the second flow path (P2) of the refrigerant heat exchanger (22). The other end of the third pipe (33) is connected to a liquid-side line of the second refrigerant circuit (R2). One end of the bypass pipe (34) is connected to an intermediate portion of the first pipe (31). The other end of the bypass pipe (34) is connected to an intermediate portion of the second pipe (32). The first pipe (31) is provided with a first on-off valve (35) between a connecting portion with the bypass pipe (34) and the fifth flow path (P5). The bypass pipe (34) is provided with a second on-off valve (36).

[0050] The hot water supply unit (20) includes part of the water circuit (W). The hot water supply unit (20) has the first water heat exchanger (23) and the second water heat exchanger (26) described above, and also a pump (40), a tank (41), and an internal heat exchanger (42) as components of the water circuit (W).

[0051] The pump (40) circulates water in the water circuit (W). In FIG. 1, the circulation direction of water in the water circuit (W) is indicated by the arrows.

[0052] The tank (41) stores water (or more precisely, hot water) supplied to the target. The tank (41) is a hollow container and contains a hot water storage space (41a). The tank (41) is connected with a water supply pipe (43) and a hot water discharge pipe (44). One end of the water supply pipe (43) is connected to a bottom portion of the tank (41), and the other end of the water supply pipe (43) is connected to a water pipe. When the amount of water in the tank (41) decreases, the water supply pipe (43) supplies low-temperature water in the water pipe to the tank (41). One end of the hot water discharge pipe (44) is connected to an upper portion of the tank (41), and the other end of the hot water discharge pipe (44) is connected to a predetermined target of hot water supply. The hot water discharge pipe (44) supplies high-temperature water in the tank (41) to the target of hot water supply such as a faucet, a shower, or a bathtub.

[0053] The internal heat exchanger (42) is disposed in the hot water storage space (41a). The internal heat exchanger (42) of this embodiment is a heat transfer tube formed in a helical shape. Warm water heated in the first water heat exchanger (23) and the second water heat exchanger (26) flows in the internal heat exchanger (42). The internal heat exchanger (42) exchanges heat between the hot water flowing therein and the water therearound. As a result, the water in the hot water storage space (41a) is heated by the internal heat exchanger (42). In this manner, the tank (41) of this embodiment stores water indirectly heated by the first refrigerant of the first water heat exchanger (23).

[0054] The water circuit (W) has a main flow path (50), a hot water supply-side flow path (51), and a heat-side flow path (52). An outflow end of the main flow path (50) is connected with an inflow end of the hot water supply-side flow path (51) and an inflow end of the heat-side flow path (52). The water circuit (W) is connected with a three-way valve (53). The three-way valve (53) switches between a first state to communicate the main flow path (50) and the hot water supply-side flow path (51) with each other and a second state to communicate the main flow path (50) and the heat-side flow path (52) with each other.

[0055] The main flow path (50) is connected with the pump (40), the fourth flow path (P4) of the first water heat exchanger (23), and the sixth flow path (P6) of the second water heat exchanger (26) in sequence.

[0056] The hot water supply-side flow path (51) has an inflow pipe (51a) and an outflow pipe (51b). The internal heat exchanger (42) is connected between the inflow pipe (51a) and the outflow pipe (51b).

[0057] The heat-side flow path (52) is connected with a utilization-side heat exchanger (6) of the heating device (5). The utilization-side heat exchanger (6) heats air in a target space (an indoor space). The utilization-side heat exchanger (6) is configured as a fin-and-tube heat exchanger or a radiant panel. The utilization-side heat exchanger (6) is configured as an air heat exchanger that directly heats air in the target space, or a floor heating heat exchanger that heats a floor of the target space.

[0058] The hot water supply unit (20) has a supply pipe (52a) and a return pipe (52b) as part of the elements of the heat-side flow path (52). The supply pipe (52a) is a flow path to supply the hot water heated in the first water heat exchanger (23) and the second water heat exchanger (26) to the utilization-side heat exchanger (6). The return pipe (52b) is a flow path to return the water having dissipated heat in the utilization-side heat exchanger (6) to the main flow path (50).

[0059] The hot water supply unit (20) also has a heater unit (54) and an expansion tank (55) as components of the water circuit (W). The heater unit (54) is provided on the main flow path (50) and heats water in the water circuit (W) as an auxiliary unit. The expansion tank (55) communicates with the main flow path (50) and reduces an increase in water pressure in the water circuit (W).(2) Structure of Hot Water Supply Unit

[0060] A structure of the hot water supply unit (20) will be described with reference to FIGS. 1 to 5. In the following description, the terms such as "top," "bottom," "front," "back," "right," and "left" refer to the directions of the arrows in FIG. 2.(2-1) Casing

[0061] As shown in FIG. 2, the hot water supply system (1) has a casing (60) disposed in an indoor space (I). The indoor space (I) is a space formed in a building, and includes not only a living space but also a non-living space, such as a corridor, a basement, a warehouse, or a garage. The casing (60) is placed on the floor surface of the indoor space (I). The casing (60) has a hollow box shape. The casing (60) has a rectangular parallelepiped outer shape. The height of the casing (60) in the top-bottom direction is greater than the length of the casing (60) in the front-back direction and the width of the casing (60) in the left-right direction. The casing (60) includes a top plate (61), a bottom plate (62), a front plate (63), a back plate (64), a right plate (65), and a left plate (66). The top plate (61) forms an upper surface of the casing (60), and the bottom plate (62) forms a lower surface of the casing (60). The front plate (63) forms a front surface, a first side surface of the casing (60), and the back plate (64) forms a back surface, a second side surface of the casing (60). The right plate (65) forms a right surface, a third side surface of the casing (60), and the left plate (66) forms a left surface, a fourth side surface of the casing (60).

[0062] A partition plate (67) is provided in the casing (60). The partition plate (67) partitions the internal space of the casing (60) into the upper space and the lower space. Specifically, the partition plate (67) separates the internal space of the casing (60) into a first space (S1) and a second space (S2). The first space (S1) is formed in an upper portion of the casing (60). The second space (S2) extends from an intermediate portion to a lower portion of the casing (60). The first space (S1) and the second space (S2) have a rectangular parallelepiped shape. The height of the second space (S2) is greater than the height of the first space (S1). The tank (41) is disposed in the second space (S2). In other words, the tank (41) is placed on the bottom plate (62) of the casing (60).

[0063] When the casing (60) is placed, a working space (S3) is secured in front of the casing (60). A first access opening (A1) is formed in an upper portion of the front plate (63) of the casing (60). A first opening / closing cover (68) as part of the front plate (63) is detachably attached to the first access opening (A1). The operator can access the first space (S1) in the casing (60) from the working space (S3) through the first access opening (A1).

[0064] As shown in FIG. 4, a second access opening (A2) is formed in the top plate (61). A second opening / closing cover (69) as part of the top plate (61) is detachably attached to the second access opening (A2). The operator can access the first space (S1) in the casing (60) from the working space (S3) through the second access opening (A2). A structure of the second opening / closing cover (69) will be described in detail later.(2-2) Layout of Each Component in First Space

[0065] FIG. 3 shows the layout of each component including a refrigerant unit (U) and an electric component unit (71). FIG. 3 schematically shows pipes that connect the components, and connecting portions between these pipes. Thus, the positions and shapes of these pipes and connecting portions are not limited to those shown in FIG. 3.

[0066] Each component of the hot water supply unit (20) is disposed in the first space (S1). As shown in FIG. 3, the refrigerant unit (U) having the first refrigerant circuit (R1) is disposed in the first space (S1). The refrigerant unit (U) includes the entire part of the first refrigerant circuit (R1) as a closed circuit. The refrigerant unit (U) has the first compressor (21), the refrigerant heat exchanger (22), the first expansion valve (24), and the first water heat exchanger (23) as components of the first refrigerant circuit (R1).

[0067] The refrigerant unit (U) is closer to the front plate (63) than to the back plate (64). The refrigerant unit (U) is closer to the left plate (66) than to the right plate (65). The first compressor (21) is disposed near the first access opening (A1). The first compressor (21) is positioned so that it can be seen from the outside of the casing (60) through the first access opening (A1) when the first opening / closing cover (68) is removed. The refrigerant unit (U) is located above the tank (41). The refrigerant unit (U) overlaps with the tank (41) in the vertical direction.

[0068] The refrigerant heat exchanger (22) and the first water heat exchanger (23) are disposed behind the first compressor (21). In this embodiment, the refrigerant heat exchanger (22) is disposed to the right of the first water heat exchanger (23). The first expansion valve (24) is disposed between the refrigerant heat exchanger (22) and the first compressor (21) or between the first water heat exchanger (23) and the first compressor (21).

[0069] The hot water supply unit (20) has a support (70) that supports the refrigerant unit (U). The support (70) is located below the refrigerant unit (U) and supports the support (70) from below. The support (70) can be pulled out from the first access opening (A1) along the bottom plate (62). The bottom plate (62) is provided with a guide member that guides the support (70) in the front-back direction in one preferred embodiment. A structure of the support (70) will be described in detail later.

[0070] The electric component unit (71) is provided in the first space (S1). The electric component unit (71) is disposed above the tank (41). The electric component unit (71) overlaps with the tank (41) in the vertical direction.

[0071] The electric component unit (71) includes a control board for controlling each component of the hot water supply unit (20). The electric component unit (71) is disposed near the first access opening (A1). The electric component unit (71) is positioned so that it can be seen from the outside of the casing (60) through the first access opening (A1) when the first opening / closing cover (68) is removed.

[0072] The second water heat exchanger (26) is disposed behind the electric component unit (71). The first on-off valve (35) and the second on-off valve (36) are disposed between the second water heat exchanger (26) and the electric component unit (71). The first pipe (31) and the third pipe (33) as refrigerant pipes are disposed around the second water heat exchanger (26). The first pipe (31) and the third pipe (33) extend in the vertical direction in the first space (S1).

[0073] The first space (S1) has a connection space (75) formed behind the electric component unit (71). The connection space (75) is formed in the front side of the first space (S1). A first connecting portion (C1), a second connecting portion (C2), a third connecting portion (C3), and a fourth connecting portion (C4) are disposed in the connection space (75).

[0074] The first connecting portion (C1) and the second connecting portion (C2) form water-side connecting portions which can detachably connect the first water heat exchanger (23) and the water circuit (W). As shown in FIG. 1, the first connecting portion (C1) connects the outflow-side water pipe of the fourth flow path (P4) of the first water heat exchanger (23) and the water circuit (W). The second connecting portion (C2) connects the inflow-side water pipe of the fourth flow path (P4) of the first water heat exchanger (23) and the water circuit (W). The third connecting portion (C3) and the fourth connecting portion (C4) form heating medium-side connecting portions which can detachably connect the refrigerant heat exchanger (22) and the second refrigerant circuit (R2). The third connecting portion (C3) connects the gas-side refrigerant pipe of the second flow path (P2) of the refrigerant heat exchanger (22) and the second refrigerant circuit (R2). The fourth connecting portion (C4) connects the liquid-side refrigerant pipe of the second flow path (P2) of the refrigerant heat exchanger (22) and the second refrigerant circuit (R2). The first connecting portion (C1) and the second connecting portion (C2) may connect the first water heat exchanger (23) and the water circuit (W) directly, or may connect the first water heat exchanger (23) and the water circuit (W) indirectly via pipes. The third connecting portion (C3) and the fourth connecting portion (C4) may connect the refrigerant heat exchanger (22) and the second refrigerant circuit (R2) directly, or may connect the refrigerant heat exchanger (22) and the second refrigerant circuit (R2) indirectly via pipes.

[0075] The refrigerant unit (U) is closer to the front plate (63) than the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) are. The refrigerant unit (U) is positioned not to overlap in the front-back direction with the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4).

[0076] A water circuit-side space (76) in which the components of the water circuit (W) are disposed is formed in the rear side of the first space (S1). The pump (40), the heater unit (54), the three-way valve (53), and the expansion tank (55) are disposed in the water circuit-side space (76). The inflow pipe (51a), the outflow pipe (51b), the supply pipe (52a), and the return pipe (52b) are disposed as water pipes in the water circuit-side space (76).

[0077] The supply pipe (52a) and the return pipe (52b) run through the top plate (61) and are connected to the water pipes outside the casing (60). The inflow pipe (51a) and the outflow pipe (51b) run through the partition plate (67) and are connected to the internal heat exchanger (42).

[0078] The first pipe (31), the second pipe (32), and the third pipe (33) are disposed in the first space (S1). The other end-side part of the first pipe (31) extends backward along the right plate (65). The second pipe (32) is disposed in an intermediate portion of the first space (S1) in the front-back direction and extends in the left-right direction from the refrigerant heat exchanger (22) to the second heat exchanger (22). The other end-side part of the third pipe (33) extends backward along the right plate (65).

[0079] Although not shown, other components of the water circuit (W) are disposed in the first space (S1). The other components include a drainage valve, a ball valve, a flow rate sensor, and a filter. The other components are positioned closer to the front plate (63) than to the back plate (64) in one preferred embodiment.(2-3) Connecting Portions on Top Plate and Peripheral Structure

[0080] As shown in FIG. 2 and FIG. 4, the top plate (61) is provided with a first refrigerant joint (81), a second refrigerant joint (82), a first water joint (83), a second water joint (84), a third water joint (85), and a fourth water joint (86). These joints are located outside the casing (60). These joints couple the pipes in the casing (60) with the pipes outside the casing (60).

[0081] Specifically, the lower end of the first refrigerant joint (81) is connected with the third pipe (33), and the lower end of the second refrigerant joint (82) is connected with the first pipe (31). The lower end of the first water joint (83) is connected with the supply pipe (52a), the lower end of the second water joint (84) is connected with the return pipe (52b), the lower end of the third water joint (85) is connected with the water supply pipe (43), and the lower end of the fourth water joint (86) is connected with the hot water discharge pipe (44).

[0082] After installing the casing (60) in the indoor space (I), the operator connects the joints with the pipes outside the casing (60). Specifically, the upper end of the first refrigerant joint (81) is connected with a first connection pipe (91) coupled with the outdoor unit (10) and located on the liquid side. The upper end of the second refrigerant joint (82) is connected with a second connection pipe (92) coupled with the outdoor unit (10) and located on the gas side. The upper end of the first water joint (83) is connected with a third water pipe (95) of the heating device (5) that is located on the inflow side. The upper end of the second water joint (84) is connected with a fourth water pipe (96) of the heating device (5) that is located on the outflow side. The upper end of the third water joint (85) is connected with a first water pipe (93) for water supply. The upper end of the fourth water joint (86) is connected with a second water pipe (94) for hot water supply.

[0083] The first water joint (83), the second water joint (84), the third water joint (85), and the fourth water joint (86) form first outer connecting portions, and the first refrigerant joint (81) and the second refrigerant joint (82) form second outer connecting portions.

[0084] In this embodiment, the first outer connecting portions (83, 84, 85, 86) and the second outer connecting portions (81, 82) are arranged in the left-right direction along the back plate (64). The second access opening (A2) is formed in front of the first outer connecting portions (83, 84, 85, 86) and the second outer connecting portions (81, 82). The second access opening (A2) is formed from near the first outer connecting portions (83, 84, 85, 86) and the second outer connecting portions (81, 82) to the front plate (63).

[0085] The second opening / closing cover (69) opens and closes the second access opening (A2). A rear frame (F) extending in the left-right direction is formed behind the second opening / closing cover (69). The first outer connecting portions (83, 84, 85, 86) and the second outer connecting portions (81, 82) are formed between the rear frame (F) and the second opening / closing cover (69). Specifically, the rear frame (F) and the second opening / closing cover (69) form holes in the positions corresponding to the joints (81, 82, 83, 84, 85, 86). In this embodiment, each of the front edge of the rear frame (F) and the rear edge of the second opening / closing cover (69) has arc-shaped grooves, and these grooves form the holes through which the joints (81, 82, 83, 84, 85, 86) or the pipes pass. Only one of the rear frame (F) or the second opening / closing cover (69) may have the grooves that form the holes.(2-4) Configuration for Response to Leakage of Refrigerant

[0086] As shown in FIG. 5, the support (70) of this embodiment forms an inner casing that houses the refrigerant unit (U). The support (70) has a rectangular parallelepiped box shape. The components of the refrigerant unit (U) such as the compressor (21) and others are placed on the bottom surface of the support (70). An opening (70a) is formed in a sidewall of the support (70). The opening (70a) allows the inside of the support (70) and the outside of the support (70) to communicate with each other. The opening (70a) is formed in the left sidewall of the support (70), but may be formed in the front sidewall, the rear sidewall, or the right sidewall. The opening (70a) is formed in a lower portion of the support (70), or more precisely, at a position along the bottom portion of the support (70). The opening (70a) is configured as a long hole that extends in the front-back direction. The opening (70a) may be a circular hole.

[0087] The partition plate (67) of this embodiment has a partition plate body (67a) on which the refrigerant unit (U) is placed and step portions (67b) which are recessed downward from the outer edge of the partition plate body (67a). The partition plate (67) of this embodiment has the step portion (67b) on both the left and right sides of the partition plate body (67a). A relay groove (77) is defined by the inside of the step portion (67b). The relay groove (77) has a rectangular shape when viewed in the cross section orthogonal to the front-back direction. The relay groove (77) extends in the front-back direction along the opening (70a). The relay groove (77) forms part of the first space (S1).

[0088] The casing (60) has communication paths (78) that allow the first space (S1) and the indoor space (I) located outside the casing (60) to communicate with each other. The communication path (78) is open toward the indoor space (I). The communication path (78) of this embodiment is formed in both the left plate (66) and the right plate (65). The communication path (78) is located at the same level as the relay groove (77) and is directly connected to the relay groove (77). The refrigerant unit (U) and the electric component unit (71) are located at higher positions than the communication path (78).

[0089] The hot water supply unit (20) has a refrigerant sensor (79) that detects leakage of a refrigerant. In this embodiment, the refrigerant sensor (79) is disposed near the opening (70a). More precisely, the refrigerant sensor (79) is distanced 10 cm or less away from the opening (70a).(2-5) Controller and Alerting Device

[0090] As schematically shown in FIG. 1, the hot water supply unit (20) has a controller (120) and an alerting device (121). The controller (120) includes a microcomputer and a memory device. The memory device stores software for operating the microcomputer. The controller (120) receives detection signals from the refrigerant sensor (79).

[0091] The alerting device (121) is an example of a device for response to leakage of a refrigerant. The alerting device (121) provides the user with first information on leakage of a refrigerant through sounds or light. If the concentration of a refrigerant detected by the refrigerant sensor (79) is higher than or equal to a predetermined value, the controller (120) instructs the alerting device (121) to release the first information.(3) Operation

[0092] In the operation of the hot water supply system (1), the second refrigerant circuit (R2) performs a subcritical cycle or a supercritical cycle, and at the same time the first refrigerant circuit (R1) performs a subcritical cycle. The second refrigerant circuit (R2) selectively performs a first operation and a second operation. The water circuit (W) selectively performs a third operation or a fourth operation.

[0093] In the first operation, the four-way switching valve (14) turns into the first state, the first on-off valve (35) turns into the open state, and the second on-off valve (36) turns into the closed state. In the first operation, the refrigerant compressed by the second compressor (11) dissipates heat in the second water heat exchanger (26) and the refrigerant heat exchanger (22), then is decompressed by the second expansion valve (13), and then evaporates in the outdoor heat exchanger (12).

[0094] In the second operation, the four-way switching valve (14) turns into the first state, the first on-off valve (35) turns into the closed state, and the second on-off valve (36) turns into the open state. In the first operation, the refrigerant compressed by the second compressor (11) bypasses the second water heat exchanger (26), then dissipates heat in the refrigerant heat exchanger (22), then is decompressed by the second expansion valve (13), and then evaporates in the outdoor heat exchanger (12).

[0095] In the first refrigerant circuit (R1), the refrigerant compressed by the first compressor (21) dissipates heat in the first water heat exchanger (23), then is decompressed by the first expansion valve (24), and then evaporates in the refrigerant heat exchanger (22).

[0096] In the third operation, the three-way valve (53) turns into the first state. In the third operation, the water transported by the pump (40) is heated by only the first water heat exchanger (23) or both the second water heat exchanger (26) and the first water heat exchanger (23). The heated water dissipates heat to the water in the hot water storage space (41a) in the internal heat exchanger (42). As a result, hot water is produced in the tank (41).

[0097] In the fourth operation, the three-way valve (53) turns into the second state. In the fourth operation, the water transported by the pump (40) is heated by only the first water heat exchanger (23) or both the second water heat exchanger (26) and the first water heat exchanger (23). The heated water dissipates heat to the air in the target space in the utilization-side heat exchanger (6) of the heating device (5), and as a result, the target space is heated.(4) Operator's Operation

[0098] To ship out and transport the hot water supply unit (20), the operator moves the refrigerant unit (U) and the casing (60) separately. This is because if the hot water supply unit (20) is transported while the refrigerant unit (U) is disposed in the first space (S1) of the casing (60), the center of gravity of the hot water supply unit (20) is positioned higher and it is difficult to conduct the transporting operation and the installing operation. The operator can transport the refrigerant unit (U) separate from the casing (60) with the support (70).

[0099] Next, the operator loads the refrigerant unit (U) and the support (70) into the casing (60). Specifically, the operator loads the support (70) that supports the refrigerant unit (U) from the working space (S3) to the first space (S1) through the first access opening (A1).

[0100] The operator connects the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) through the first access opening (A1). Accordingly, the refrigerant unit (U) is connected with the water circuit (W) and the second refrigerant circuit (R2). The first refrigerant circuit (R1) may be filled with a refrigerant before the transporting operation or may be at the installing operation.

[0101] The operator connects the pipes to the joints on the top plate (61). Specifically, the operator connects the first connection pipe (91) to the first refrigerant joint (81), and the second connection pipe (92) to the second refrigerant joint (82). The operator connects each of the water pipes (93, 94, 95, 96) to the associated one of the water joints (83, 84, 85, 86).

[0102] The operator can detach the second opening / closing cover (69) on the top plate (61) while the pipes are connected to the joints (81, 82, 83, 84, 85, 86). This is because as shown in FIG. 4, the pipes (91, 92, 93, 94, 95, 96) are located in the grooves between the second opening / closing cover (69) and the rear frame (F). Accordingly, the operator can connect or disconnect the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) through the second access opening (A2).

[0103] The operator can do maintenance of the refrigerant unit (U) after unloading the refrigerant unit (U) to the outside of the casing (60). Specifically, the operator in the working space (S3) detaches the first opening / closing cover (68) from the casing (60) to expose the first access opening (A1). The operator disconnects the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) through the first access opening (A1). As a result, the refrigerant unit (U) is detached from the water circuit (W) and the second refrigerant circuit (R2). Also in this state, the first refrigerant circuit (R1) of the refrigerant unit (U) remains a closed circuit, and thus the risk that a flammable refrigerant may leak from the first refrigerant circuit (R1) is smaller than when the refrigerant unit (U) is detached in the first refrigerant circuit (R1). Since the refrigerant in the second refrigerant circuit (R2) is carbon dioxide, no significant problem occurs even if the refrigerant leaks from the second refrigerant circuit (R2).

[0104] The operator moves the support (70) forward through the first access opening (A1). Accordingly, it is possible to unload the refrigerant unit (U) and the support (70) to the outside of the casing (60) together through the first access opening (A1). The refrigerant unit (U) is located closer to the front plate (63) than the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) are. Accordingly, it is possible to reduce the refrigerant unit (U) interfering with these connecting portions, and thus it is possible to unload the refrigerant unit (U) easily.

[0105] The operator performs maintenance of the removed refrigerant unit (U) not in the indoor space (I) but in the outdoor space. Accordingly, even if a flammable refrigerant leaks from the first refrigerant circuit (R1), it is possible to reduce the problems resulting from this leakage. After completing the maintenance of the refrigerant unit (U), the operator returns the refrigerant unit (U) and the support (70) to the original positions together. Then, the operator reconnects the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4).(5) Operation at Leakage of Refrigerant

[0106] The operation at leakage of a refrigerant will be described. FIG. 5 shows the leaked refrigerant by the broken arrows. If a refrigerant leaks from the first refrigerant circuit (R1), this refrigerant accumulates in the support (70). The refrigerant in the support (70) discharges into the first space (S1) (or more precisely, the space between the casing (60) and the support (70)). The refrigerant in the first space (S1) flows down to the relay groove (77) inside the step portion (67b). The refrigerant in the relay groove (77) discharges to the outside of the casing (60) through the communication path (78) of the casing (60).

[0107] Since the refrigerant unit (U) is located above the tank (41), the refrigerant having flowed out from the first refrigerant circuit (R1) is also located at a high position. Accordingly, the distance the refrigerant must travel to reach the height of the bottom plate (62) of the casing (60) becomes longer. Accordingly, the refrigerant having flowed out of the communication path (78) diffuses before reaching the floor of the indoor space (I). As a result, it is possible to reduce the concentration of the refrigerant. In particular, when falling downward, the refrigerant diffuses in the horizontal direction, and thus it is possible to reduce the concentration of the refrigerant near the floor surface. Accordingly, it is possible to prevent the concentration of the refrigerant from reaching the lower flammable limit (LFL).

[0108] Since the communication path (78) is located at a lower position than the refrigerant unit (U), it is possible to reliably guide the flammable refrigerant having a higher specific gravity than air to the communication path (78).

[0109] The support (70), which is the inner casing, houses the refrigerant unit (U). Accordingly, it is possible to delay the time required for the refrigerant to discharge to the outside of the casing (60) through the communication path (78). Accordingly, it is possible to limit the amount of a refrigerant flowing out from the communication path (78), and thus it is possible to lower the concentration of the refrigerant in the indoor space (I).

[0110] The refrigerant sensor (79) is disposed near the opening (70a). Accordingly, the refrigerant sensor (79) can detect leakage of a refrigerant immediately. In particular, the refrigerant sensor (79) is located on the flow path between the opening (70a) and the communication path (78), and thus the refrigerant sensor (79) can detect leakage of a refrigerant immediately. If the refrigerant sensor (79) detects leakage of a refrigerant, the controller (120) instructs the alerting device (121) to release the first information. Accordingly, the user can respond to the leakage of a refrigerant immediately.(6) Advantages of Embodiment(6-1)

[0111] The refrigerant unit (U) is disposed above the tank (41). According to this configuration, the refrigerant unit (U) is located at a high position. Accordingly, the refrigerant having leaked from the refrigerant unit (U) gradually diffuses in the air before reaching the floor surface of the indoor space (I). Accordingly, it is possible to reduce the concentration of the leaked refrigerant.(6-2)

[0112] The casing (60) has the first side surface (63) having the first access opening (A1) of the first space (S1) which houses the refrigerant unit (U) and the second side surface (64) located opposite to the first side surface (63) in the casing (60). The hot water supply unit further includes the support (70) that supports the refrigerant unit (U) and that can be loaded and unloaded through the first access opening (A1).

[0113] According to this configuration, by moving the support (70) to the outside of the casing (60) through the first access opening (A1), it is possible to unload the refrigerant unit (U) to the outside of the casing (60). Accordingly, the operator can perform a predetermined operation while the refrigerant unit (U) is unloaded to the outdoor space, and thus it is possible to reduce the risk that the first refrigerant, a flammable refrigerant, may leak.

[0114] In addition, the operator can move the refrigerant unit (U) and the casing (60) separately while the refrigerant unit (U) is unloaded to the outside the casing (60). If the hot water supply unit (20) is transported while the refrigerant unit (U) is placed in the casing (60), the center of gravity of the hot water supply unit (20) is positioned higher. This is because the refrigerant unit (U) is located above the tank (41) and, during transportation, the tank (41) does not store water. In contrast, if the refrigerant unit (U) and the casing (60) are transported separately, the center of gravity of the casing (60) is positioned lower during transportation. Accordingly, it is possible to transport the hot water supply unit (20) easily.(6-3)

[0115] The refrigerant unit (U) has the water-side connecting portions (C1, C2) that detachably connect the refrigerant heat exchanger (22) and the water circuit (W), and the heating medium-side connecting portions (C3, C4) that detachably connect the first water heat exchanger (23) and the second refrigerant circuit (R2).

[0116] According to this configuration, by disconnecting the water-side connecting portions (C1, C2), it is possible to detach the first water heat exchanger (23) from the water circuit (W). By disconnecting the heating medium-side connecting portions (C3, C4), it is possible to detach the refrigerant heat exchanger (22) from the second refrigerant circuit (R2). As a result, the refrigerant unit (U) detached from the water circuit (W) and the second refrigerant circuit (R2) can be unloaded to the outside of the casing (60) through the first access opening (A1).(6-4)

[0117] The refrigerant unit (U) is closer to the first side surface (63) than the water-side connecting portions (C1, C2) and the heating medium-side connecting portions (C3, C4) are. In particular, the refrigerant unit (U) does not overlap in the front-back direction with the water-side connecting portions (C1, C2) and the heating medium-side connecting portions (C3, C4). According to this configuration, it is possible to load and unload the refrigerant unit (U) easily.(6-5)

[0118] The casing (60) has the top plate (61) having the second access opening (A2) of the first space (S1). According to this configuration, the operator can access the water-side connecting portions (C1, C2) and the heating medium-side connecting portions (C3, C4) from above the casing (60) through the second access opening (A2).(6-6)

[0119] Further, the first outer connecting portions (83, 84, 85, 86) provided on the top plate (61) of the casing (60) and connected with the water pipes (93, 94, 95, 96) of the water circuit (W) extending from the outside of the casing (60) are provided, and also the second outer connecting portions (81, 82) provided on the top plate (61) of the casing (60) and connected with the refrigerant pipes (91, 92) of the second refrigerant circuit (R2) extending from the outside of the casing (60) are provided.

[0120] According to this configuration, the distance from the first water heat exchanger (23) to the first outer connecting portions (83, 84, 85, 86) and the distance from the refrigerant heat exchanger (22) to the second outer connecting portions (81, 82) are shortened. Accordingly, it is possible to shorten the pipe length from the first water heat exchanger (23) to the first outer connecting portions (83, 84, 85, 86) and the pipe length from the refrigerant heat exchanger (22) to the second outer connecting portions (81, 82).(6-7)

[0121] The casing (60) has the communication path (78) that allows the indoor space (I) to communicate with the first space (S1) that houses the refrigerant unit (U). According to this configuration, when a refrigerant leaks from the first refrigerant circuit (R1) of the refrigerant unit (U), it is possible to discharge this refrigerant from the first space (S1) to the indoor space (I) located outside the casing (60) through the communication paths (78). As a result, it is possible to accelerate diffusion of the refrigerant before the refrigerant drops onto the floor surface, and thus it is possible to reduce the concentration of the refrigerant.

[0122] The communication paths (78) are located at lower positions than the refrigerant unit (U). According to this configuration, the communication paths (78) are formed at a lower position than the refrigerant unit (U), and thus it is easier to guide the refrigerant having leaked from the refrigerant circuit (R1) to the communication path (78). Accordingly, it is possible to accelerate diffusion of the refrigerant outside the casing (60). The refrigerant unit (U) and the electric component unit (71) are located at higher positions than the communication paths (78). Accordingly, the refrigerant unit (U) and the electric component unit (71) are less affected by the leaked refrigerant.

[0123] The hot water supply unit (20) further includes the inner casing (70) disposed in the first space (S1) and housing the refrigerant unit (U). The inner casing (70) has the opening (70a) that allows the outside and the inside of the inner casing (70) to communicate with each other. According to this configuration, it is possible to reduce the speed at which a refrigerant discharges to the outside of the casing (60), and thus it is possible to reduce the concentration of the refrigerant outside the casing (60).

[0124] The refrigerant sensor (79) is disposed in the inner casing (70) or near the opening (70a). According to this configuration, the refrigerant sensor (79) can detect leakage of a refrigerant immediately.(7) Variations

[0125] The above embodiment may be modified as the following variations. In the following, the differences from the above embodiment will be described.(7-1) First Variation

[0126] In the first variation shown in FIG. 6, the refrigerant sensor (79) is disposed in the support (70), which is an inner casing. Since the support (70) houses the refrigerant unit (U), the concentration of the refrigerant having leaked in the support (70) increases immediately. By providing the refrigerant sensor (79) in the support (70), it is possible to detect leakage of a refrigerant immediately.

[0127] In particular, in the first variation, by providing the refrigerant sensor (79) near the opening (70a) through which the refrigerant flows, it is possible to detect leakage of a refrigerant immediately. The refrigerant sensor (79) may be disposed on the opening (70a).(7-2) Second Variation

[0128] In the second variation shown in FIG. 7, the refrigerant sensor (79) is disposed near the communication path (78). The distance between the refrigerant sensor (79) and the associated communication path (78) is 10 cm or less. The refrigerant sensor (79) of this variation is located outside the casing (60). However, the refrigerant sensor (79) may be disposed in the casing (60), or may be disposed on the communication path (78). The refrigerant sensor (79) may be disposed on the relay groove (77). According to these configurations, a refrigerant flows around the refrigerant sensor (79) easily, and thus it is possible to detect leakage of a refrigerant immediately.

[0129] In the second variation, the side plates (65, 66) of the casing (60) are provided with guide plates (66a). The guide plates (66a) are formed above the communication path (78). The guide plates (66a) extend obliquely downward from the side plates (65, 66). For example, the guide plate (66a) is formed by lifting part of the side plate that is formed between a pair of slits extending in the vertical direction. The refrigerant sensor (79) is positioned to overlap with the guide plate (66a) in the top-bottom direction and overlap with the communication path (78) in the lateral direction.

[0130] In the second variation shown in FIG. 7, no inner casing is provided. More precisely, the support (70) is formed as a plate that is placed on the partition plate (67) and laid along the partition plate (67). The refrigerant unit (U) is placed on the support (70). According to this configuration, the refrigerant having leaked from the refrigerant unit (U) can be discharged to the outside of the casing (60) immediately, and thus it is possible to reduce the concentration of the refrigerant in the casing (60) immediately.(7-3) Third Variation

[0131] As shown in FIG. 8, the hot water supply unit (20) of the third variation has a shielding member (98). The shielding member (98) is disposed in the front side of the first space (S1). The shielding member (98) is disposed between the refrigerant unit (U) and the connection space (75). The shielding member (98) shields the third connecting portion (C3) and the fourth connecting portion (C4) from the first refrigerant circuit (R1). The shielding member (98) is formed as a plate of which the thickness direction is the left-right direction. In top view, the shielding member (98) extends from near the front end of the casing (60) to an intermediate position of the casing (60) in the front-back direction. The upper end of the shielding member (98) is located at a higher position than the upper end of the first compressor (21). The shielding member (98) of this variation is integrated with the support (70). A lower portion of the shielding member (98) is continuous with the support (70). The shielding member (98) may be separate from the support (70).

[0132] The third connecting portion (C3) and the fourth connecting portion (C4) may be subject to brazing, welding, or others for pipe connection, and may be subject to cutting or others for pipe separation. These operations may cause sparks to fly toward the first refrigerant circuit (R1). Since the shielding member (98) shields the third connecting portion (C3) and the fourth connecting portion (C4) from the first refrigerant circuit (R1), it is possible to reduce sparks flying toward the first refrigerant circuit (R1). As a result, it is possible to reduce the risk that a flammable refrigerant may ignite.(7-4) Fourth Variation

[0133] As shown in FIG. 9, instead of the second refrigerant circuit (R2) of the embodiment, the hot water supply system (1) of the fourth variation has a primary-side circulation circuit (100) as a heating medium circuit. The primary-side circulation circuit (100) is filled with a heating medium such as water or antifreeze solution. The configuration of part of the primary-side circulation circuit (100) that is involved in the hot water supply unit (20) is the same as that of the embodiment. The primary-side circulation circuit (100) has a circulation pump (101) and an underground heat exchanger (102) as components installed in the outdoor space. The circulation pump (101) circulates the heating medium in the primary-side circulation circuit (100). The underground heat exchanger (102) is a heat transfer tube for providing underground heat with the heating medium and has a helical shape, for example. The heating medium heated by the underground heat exchanger (102) dissipates heat in the refrigerant heat exchanger (22) and is used to produce hot water in the tank (41).(8) Other Embodiments

[0134] The hot water supply system (1) may be a system that supplies hot water from the tank (41) only to the heating device (5).

[0135] The hot water supply unit (20) may not have the second water heat exchanger (26). In this case, the second refrigerant circuit (R2) is configured without the second water heat exchanger (26), the bypass pipe (34), the first on-off valve (35), and the second on-off valve (36).

[0136] The water heated by the first water heat exchanger (23) may be accumulated directly in the tank (41). In other words, the tank (41) may store the water directly heated by the first refrigerant.

[0137] The support (70) may have a box shape that houses the refrigerant unit (U). In this case, the side plate of the support (70) may form the shielding member (98) of the first variation.

[0138] The refrigerant unit (U) and the electric component unit (71) do not necessarily overlap with the tank (41) in the vertical direction. The refrigerant unit (U) and the electric component unit (71) only need to be located at higher positions than the upper end of the tank (41).

[0139] The heating medium-side connecting portions (C3, C4) and the water-side connecting portions (C1, C2) may be provided on a side surface of the casing (60).

[0140] The expansion mechanism may be not an expansion valve but a capillary tube or an expansion device.

[0141] The communication path (78) may be a gap formed between frames or plates of the casing (60). The communication path (78) may be located at a higher position than the refrigerant unit (U). The hot water supply unit (20) may have an inner casing that is separate from the support (70) and that houses the refrigerant unit (U).

[0142] A device activated in response to detection of leakage of a refrigerant may be a shutoff valve that opens and closes the refrigerant circuit (R1), a fan that stirs the air, or a ventilating device that operates for the indoor space (I).(9) Other Descriptions

[0143] While the embodiments and variations thereof have been described above, it will be understood that various changes in form and details may be made without departing from the spirit and scope of the claims. The embodiments, the variations, and the other embodiments may be combined and replaced with each other as long as the functions of the target of the present disclosure are not impaired.

[0144] The expressions such as "first," "second," "third," . . . , described above are used to distinguish the terms to which these expressions are given, and do not limit the number and order of the terms.INDUSTRIAL APPLICABILITY

[0145] As described above, the present disclosure is useful for a hot water supply unit.DESCRIPTION OF REFERENCE CHARACTERS

[0146] 20Hot Water Supply Unit 21First Compressor (Compressor) 22Refrigerant Heat Exchanger (Second Heat Exchanger) 23First Water Heat Exchanger (First Heat Exchanger) 24First Expansion Valve (Decompression Mechanism) 41Tank 60Casing 61Top Plate (Upper Surface) 63Front Plate (First Side Surface) 64Back Plate (Second Side Surface) 70Support (Inner Casing) 70aOpening 71Electric Component Unit 78Communication Path 79Refrigerant Sensor 81, 82Second Outer Connecting Portion 83, 84, 85, 86First Outer Connecting Portion 91, 92Refrigerant Pipe 93, 94, 95, 96Water Pipe 98Shielding Member A1First Access Opening A2Second Access Opening C1, C2Water-Side Connecting Portion C3, C4Heating Medium-Side Connecting Portion IIndoor Space R1First Refrigerant Circuit (Refrigerant Circuit) R2Second Refrigerant Circuit R2, 100Heating Medium Circuit S1First Space URefrigerant Unit WWater Circuit

Examples

Embodiment Construction

[0041]Embodiments of the present disclosure will be described in detail below with reference to the drawings. The present disclosure is not limited to the embodiments shown below, and various changes can be made within the scope without departing from the technical concept of the present disclosure. Since each of the drawings is intended to illustrate the present disclosure conceptually, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.

(1) Configuration of Hot Water Supply System

(1-1) General Configuration

[0042]A hot water supply system (1) supplies hot water to a target. The target of this embodiment includes a target of hot water supply, such as a faucet, a shower, or a bathtub, and also a heating device (5) using hot water. The hot water supply system (1) is connected to the target of hot water supply and the heating device (5) via water pipes. The hot water supply system (1) has an outdoor unit (10) disposed outdoors and a ho...

TECHNICAL FIELD

[0001] The present disclosure relates to a hot water supply unit.BACKGROUND ART

[0002] Patent Document 1 discloses a hot water supply unit. The hot water supply unit includes a refrigerant circuit having a first heat exchanger and a second heat exchanger and also a tank for hot water supply. The tank stores water heated by a refrigerant in the refrigerant circuit.CITATION LISTPATENT DOCUMENT

[0003] Patent Document 1: Japanese Unexamined Patent Publication No. 2004-132647SUMMARY OF THE INVENTIONTECHNICAL PROBLEM

[0004] The inventors of this application have invented a hot water supply unit having a casing that houses a tank and a refrigerant unit having a refrigerant circuit. The hot water supply unit (the casing) is disposed in an indoor space. The refrigerant circuit employs a flammable refrigerant as a refrigerant. The hot water supply unit is used for hot water supply or air conditioning, for example. Meanwhile, when the hot water supply unit is disposed in the indoor space as described above, there is a greater risk that the flammable refrigerant may leak.

[0005] An object of the present disclosure is to reduce the risk that a flammable refrigerant may leak.SOLUTION TO THE PROBLEM

[0006] A first aspect is directed to a hot water supply unit. The hot water supply unit includes: a refrigerant unit (U) having a refrigerant circuit (R1) configured to perform a refrigeration cycle by using a first refrigerant that is a flammable refrigerant; a tank (41) configured to store water directly or indirectly heated by the first refrigerant; and a casing (60) housing the refrigerant unit (U) and the tank (41) and disposed in an indoor space (I). The refrigerant circuit (R1) has a compressor (21), a first heat exchanger (23) configured to exchange heat between the first refrigerant in the refrigerant circuit (R1) and water in a water circuit (W), a decompression mechanism (24), and a second heat exchanger (22) configured to exchange heat between the first refrigerant in the refrigerant circuit (R1) and a heating medium in a heating medium circuit (R2, 100). The refrigerant unit (U) is disposed above the tank (41).

[0007] According to the first aspect, the refrigerant unit (U) is disposed above the tank (41), whereby the refrigerant unit (U) is located at a higher position. When a refrigerant leaks from the refrigerant circuit (R1) of the refrigerant unit (U), the flammable refrigerant having a higher specific gravity than air flows downward from the refrigerant unit (U). The refrigerant gradually diffuses in the air before reaching the floor surface of the indoor space (I). Accordingly, it is possible to reduce the concentration of the leaked refrigerant.

[0008] A second aspect is an embodiment of the first aspect. In the second aspect, the casing (60) has a first side surface (63) having a first access opening (A1) of a first space (S1) that houses the refrigerant unit (U), and a second side surface (64) located opposite to the first side surface (63) in the casing (60). The hot water supply unit further includes the support (70) that supports the refrigerant unit (U) and that can be loaded and unloaded through the first access opening (A1).

[0009] According to the second aspect, by moving the support (70) to the outside of the casing (60) through the first access opening (A1), it is possible to unload the refrigerant unit (U) to the outside of the casing (60). Accordingly, the operator can perform a predetermined operation while the refrigerant unit (U) is unloaded to the outdoor space, and thus it is possible to reduce the risk that the first refrigerant, a flammable refrigerant, may leak.

[0010] A third aspect is an embodiment of the second aspect. In the third aspect, the refrigerant unit (U) has a water-side connecting portion (C1, C2) configured to detachably connect the first heat exchanger (23) and the water circuit (W), and a heating medium-side connecting portion (C3, C4) configured to detachably connect the second heat exchanger (22) and the heating medium circuit (R2, 100).

[0011] According to the third aspect, by disconnecting the water-side connecting portions (C1, C2), it is possible to detach the first heat exchanger (23) from the water circuit (W). By disconnecting the heating medium-side connecting portions (C3, C4), it is possible to detach the second heat exchanger (22) from the heating medium circuit (R2, 100). As a result, the refrigerant unit (U) detached from the water circuit (W) and the heating medium circuit (R2, 100) can be easily unloaded to the outside of the casing (60) through the first access opening (A1).

[0012] A fourth aspect is an embodiment of the third aspect. In the fourth aspect, the refrigerant unit (U) is closer to the first side surface (63) than the water-side connecting portion (C1, C2) and the heating medium-side connecting portion (C3, C4) are.

[0013] According to the fourth aspect, the refrigerant unit (U) is closer to the first side surface (63), whereby the refrigerant unit (U) is less likely to interfere with the water circuit (W) and the heating medium circuit (R2, 100). Accordingly, it is possible to load and unload the refrigerant unit (U) easily.

[0014] A fifth aspect is an embodiment of the fourth aspect. In the fifth aspect, the casing (60) has an upper surface (61) having a second access opening (A2) of the first space (S1).

[0015] According to the fifth aspect, the operator can access the water-side connecting portions (C1, C2) and the heating medium-side connecting portions (C3, C4) from above the casing (60) through the second access opening (A2).

[0016] A sixth aspect is an embodiment of any one of the first to fifth aspects. In the sixth aspect, the hot water supply unit further includes a first outer connecting portion (83, 84, 85, 86) provided on the upper surface (61) of the casing (60) and connected with a water pipe (93, 94, 95, 96) of the water circuit (W) extending from an outside of the casing (60).

[0017] According to the sixth aspect, the refrigerant unit (U) is located above the tank (41). The first outer connecting portions (83, 84, 85, 86) are provided on the upper surface of the casing (60). Accordingly, the distance from the first heat exchanger (23) to the first outer connecting portions (83, 84, 85, 86) is shortened.

[0018] A seventh aspect is an embodiment of the sixth aspect. In the seventh aspect, the casing (60) has a first side surface (63) having a first access opening (A1) of a first space (S1) that houses the refrigerant unit (U), and a second side surface (64) located opposite to the first side surface (63) in the casing (60). The first outer connecting portion (83, 84, 85, 86) is closer to the second side surface (64) than to the first side surface (63).

[0019] An eighth aspect is an embodiment of any one of the first to seventh aspects. In the eighth aspect, the hot water supply unit further includes a second outer connecting portion (81, 82) provided on the upper surface (61) of the casing (60) and connected with a refrigerant pipe (91, 92) of the heating medium circuit (R2, 100) extending from an outside of the casing (60).

[0020] According to the eighth aspect, the refrigerant unit (U) is located above the tank (41). The second outer connecting portions (81, 82) are provided on the upper surface of the casing (60). Accordingly, the distance from the refrigerant heat exchanger (22) to the second outer connecting portions (81, 82) is shortened.

[0021] A ninth aspect is an embodiment of the eighth aspect. In the ninth aspect, the casing (60) has a first side surface (63) having a first access opening (A1) of a first space (S1) that houses the refrigerant unit (U), and a second side surface (64) located opposite to the first side surface (63) in the casing (60). The second outer connecting portion (81, 82) is closer to the second side surface (64) than to the first side surface (63).

[0022] A tenth aspect is an embodiment of any one of the first to ninth aspects. In the tenth aspect, the casing (60) has a communication path (78) that allows the indoor space (I) to communicate with the first space (S1) that houses the refrigerant unit (U).

[0023] According to the tenth aspect, when a refrigerant leaks from the first refrigerant circuit (R1) of the refrigerant unit (U), it is possible to discharge this refrigerant from the first space (S1) to the indoor space (I) located outside the casing (60) through the communication paths (78). As a result, it is possible to accelerate diffusion of the refrigerant outside the casing (60), and thus it is possible to reduce the concentration of the refrigerant.

[0024] An eleventh aspect is an embodiment of the tenth aspect. In the eleventh aspect, the communication path (78) is located at a lower position than the refrigerant unit (U).

[0025] According to the eleventh aspect, the communication paths (78) is formed at a lower position than the refrigerant unit (U), and thus it is easier to guide the refrigerant having leaked from the refrigerant circuit (R1) to the communication path (78). Accordingly, it is possible to accelerate diffusion of the refrigerant outside the casing (60).

[0026] A twelfth aspect is an embodiment of the tenth or eleventh aspect. In the twelfth aspect, the hot water supply unit further includes a refrigerant sensor (79) configured to detect leakage of the first refrigerant. The refrigerant sensor (79) is disposed on the communication path (78) or near the communication path (78).

[0027] According to the twelfth aspect, the refrigerant sensor (79) is disposed on the communication path (78) or near the communication path (78), and thus the refrigerant sensor (79) can detect leakage of a refrigerant immediately.

[0028] A thirteenth aspect is an embodiment of the tenth or eleventh aspect. In the thirteenth aspect, the hot water supply unit further includes an inner casing (70) disposed in the first space (S1) and housing the refrigerant unit (U). The inner casing (70) has an opening (70a) that allows an outside and an inside of the inner casing (70) to communicate with each other.

[0029] According to the thirteenth aspect, the refrigerant having leaked from the refrigerant circuit (R1) can be stored in the inner casing (70). The refrigerant in the inner casing (70) flows out through the opening (70a) and tends to accumulate outside the inner casing (70) in the first space (S1). This refrigerant flows out of casing (60) through the communication path (78). In this manner, it is possible to reduce the speed at which a refrigerant discharges to the outside of the casing (60), and thus it is possible to reduce the concentration of the refrigerant outside the casing (60).

[0030] A fourteenth aspect is an embodiment of the thirteenth aspect. In the fourteenth aspect, the hot water supply unit further includes a refrigerant sensor (79) configured to detect leakage of the first refrigerant. The refrigerant sensor (79) is disposed in the inner casing (70) or near the opening (70a).

[0031] According to the fourteenth aspect, the refrigerant sensor (79) is disposed in the inner casing (70) or near the opening (70a), and thus the refrigerant sensor (79) can detect leakage of a refrigerant immediately.

[0032] A fifteenth aspect is an embodiment of any one of the third to fifth aspects. In the fifteenth aspect, the hot water supply unit further includes a shielding member (98) configured to shield the heating medium-side connecting portion (C3, C4) and the refrigerant circuit (R1) from each other.

[0033] According to the fifteenth aspect, the refrigerant circuit (R1) filled with the first refrigerant that is a flammable refrigerant is shielded from the heating medium-side connecting portions (C3, C4) by the shielding member (98). Accordingly, it is possible to reduce the risk that the first refrigerant may ignite due to connection with the heating medium-side connecting portions (C3, C4).

[0034] A sixteenth aspect is an embodiment of any one of the first to fifteenth aspects. In the sixteenth aspect, the hot water supply unit further includes an electric component unit (71) housed in the casing (60). The electric component unit (71) is disposed above the tank (41).

[0035] According to the sixteenth aspect, if the refrigerant having leaked from the refrigerant circuit (R1) accumulates at the bottom portion of the casing (60), the electric component unit (71) is less affected by the refrigerant accumulated at the bottom portion.

[0036] A seventeenth aspect is an embodiment of any one of the tenth to fourteenth aspects. In the seventeenth aspect, the hot water supply unit further includes an electric component unit (71) housed in the casing (60). The electric component unit (71) is located at a higher position than the communication path (78).

[0037] According to the seventeenth aspect, the electric component unit (71) is less affected by the leaked refrigerant.

[0038] An eighteenth aspect is an embodiment of any one of the first to seventeenth aspects. In the eighteenth aspect, the heating medium circuit (R2, 100) is a second refrigerant circuit (R2) configured to perform a refrigeration cycle by using a second refrigerant.

[0039] According to the eighteenth aspect, the hot water supply unit performs a so-called binary refrigeration cycle.BRIEF DESCRIPTION OF THE DRAWINGS

[0040] [FIG. 1] FIG. 1 is a piping system diagram of a hot water supply system according to an embodiment. [FIG. 2] FIG. 2 is a perspective view of the appearance of a hot water supply unit. [FIG. 3] FIG. 3 is a schematic plan view of the layout of components in a first space. [FIG. 4] FIG. 4 is a top view of a top plate. [FIG. 5] FIG. 5 is a vertical sectional view of an internal structure of the first space in a casing. [FIG. 6] FIG. 6 is a vertical sectional view of an internal structure of a first space in a casing of a hot water supply unit according to a first variation. [FIG. 7] FIG. 7 is a vertical sectional view of an internal structure of a first space in a casing of a hot water supply unit according to a second variation. [FIG. 8] FIG. 8 is a schematic plan view of the layout of components in a first space in a hot water supply unit according to a third variation. [FIG. 9] FIG. 9 is a piping system diagram of a hot water supply system according to a fourth variation. DESCRIPTION OF EMBODIMENTS

[0041] Embodiments of the present disclosure will be described in detail below with reference to the drawings. The present disclosure is not limited to the embodiments shown below, and various changes can be made within the scope without departing from the technical concept of the present disclosure. Since each of the drawings is intended to illustrate the present disclosure conceptually, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.(1) Configuration of Hot Water Supply System(1-1) General Configuration

[0042] A hot water supply system (1) supplies hot water to a target. The target of this embodiment includes a target of hot water supply, such as a faucet, a shower, or a bathtub, and also a heating device (5) using hot water. The hot water supply system (1) is connected to the target of hot water supply and the heating device (5) via water pipes. The hot water supply system (1) has an outdoor unit (10) disposed outdoors and a hot water supply unit (20) disposed indoors.

[0043] As a circuit configuration, the hot water supply system (1) includes a first refrigerant circuit (R1), a second refrigerant circuit (R2), and a water circuit (W). The first refrigerant circuit (R1) is filled with a flammable refrigerant as a first refrigerant. The second refrigerant circuit (R2) is filled with carbon dioxide as a second refrigerant. The second refrigerant circuit (R2) is an example of a heating medium circuit, and carbon dioxide is an example of a heating medium.

[0044] The first refrigerant is propane (R290), a natural refrigerant that is highly flammable. The natural refrigerant is a refrigerant which has an ozone depletion potential of zero and a low global warming potential and thus which has less impact on the environment. Propane ignites at 500°C or less. The flammable refrigerant may be methane (R50), ethane (R170), butane (R600), or isobutane (R600a). The flammable refrigerant may be not a refrigerant that is highly flammable but a refrigerant that is slightly flammable. The slightly flammable refrigerant may be difluoromethane (R32) or tetrafluoropropene (HFO-1234yf). The first refrigerant may be a single component refrigerant comprised of one of the above refrigerants, or may be a mixed refrigerant comprised of one of the above refrigerants and another one or more of the above refrigerants.

[0045] The hot water supply system (1) has a refrigerant heat exchanger (22), a first water heat exchanger (23), and a second water heat exchanger (26). The refrigerant heat exchanger (22) is shared by the first refrigerant circuit (R1) and the second refrigerant circuit (R2), the first water heat exchanger (23) is shared by the first refrigerant circuit (R1) and the water circuit (W), and the second water heat exchanger (26) is shared by the second refrigerant circuit (R2) and the water circuit (W). The refrigerant heat exchanger (22) is an example of the first heat exchanger, and the first water heat exchanger (23) is an example of the second heat exchanger. The hot water supply system (1) performs a so-called binary refrigeration cycle by using the first refrigerant circuit (R1) and the second refrigerant circuit (R2).(1-2) Outdoor Unit

[0046] The outdoor unit (10) includes part of the second refrigerant circuit (R2). The outdoor unit (10) has a second compressor (11), an outdoor heat exchanger (12), a second expansion valve (13), a four-way switching valve (14), and a second accumulator (15) as components of the second refrigerant circuit (R2). The outdoor unit (10) has an outdoor fan (16). The second compressor (11) compresses a sucked refrigerant and discharges a compressed refrigerant. The outdoor heat exchanger (12) exchanges heat between the outdoor air transported by the outdoor fan (16) and the second refrigerant. The second expansion valve (13) decompresses a refrigerant. The four-way switching valve (14) switches between a first state indicated by the solid lines in FIG. 1 and a second state indicated by the broken lines in FIG. 1. The second accumulator (15) stores a liquid refrigerant that is to be sucked into the second compressor (11).(1-3) Circuit Configuration of Hot Water Supply Unit

[0047] The hot water supply unit (30) includes the entire part of the first refrigerant circuit (R1). The hot water supply unit (20) has a first compressor (21), the refrigerant heat exchanger (22), the first water heat exchanger (23), a first expansion valve (24), and a first accumulator (25) as components of the first refrigerant circuit (R1). The first compressor (21) compresses a sucked refrigerant and discharges a compressed refrigerant. The refrigerant heat exchanger (22) has a first flow path (P1) connected to the first refrigerant circuit (R1) and a second flow path (P2) connected to the second refrigerant circuit (R2). The refrigerant heat exchanger (22) exchanges heat between the first refrigerant in the first flow path (P1) of the first refrigerant circuit (R1) and the second refrigerant in the second flow path (P2) of the second refrigerant circuit (R2). The first water heat exchanger (23) has a third flow path (P3) connected to the first refrigerant circuit (R1) and a fourth flow path (P4) connected to the water circuit (W). The first water heat exchanger (23) exchanges heat between the first refrigerant in the third flow path (P3) of the first refrigerant circuit (R1) and the water in the fourth flow path (P4) of the water circuit (W). The first expansion valve (24) is an example of a decompression mechanism that decompresses a refrigerant. The first accumulator (25) stores a liquid refrigerant that is to be sucked into the first compressor (21). The refrigerant heat exchanger (22) and the first water heat exchanger (23) are configured as plate heat exchangers, for example.

[0048] The hot water supply unit (20) includes part of the second refrigerant circuit (R2). The hot water supply unit (20) has the first water heat exchanger (23) described above and also the second water heat exchanger (26) as components of the second refrigerant circuit (R2). The second water heat exchanger (26) has a fifth flow path (P5) connected to the second refrigerant circuit (R2) and a sixth flow path (P6) connected to the water circuit (W). The second water heat exchanger (26) exchanges heat between the second refrigerant in the fifth flow path (P5) of the second refrigerant circuit (R2) and the water in the sixth flow path (P6) of the water circuit (W). The second water heat exchanger (26) is configured as a plate heat exchanger, for example.

[0049] The hot water supply unit (20) has a first pipe (31), a second pipe (32), a third pipe (33), and a bypass pipe (34) as refrigerant pipes that form the second refrigerant circuit (R2). One end of the first pipe (31) is connected to a gas-side line of the second refrigerant circuit (R2). The other end of the first pipe (31) is connected to one end of the fifth flow path (P5) of the second water heat exchanger (26). One end of the second pipe (32) is connected to the other end of the fifth flow path (P5) of the second water heat exchanger (26). The other end of the second pipe (32) is connected to one end of the second flow path (P2) of the refrigerant heat exchanger (22). One end of the third pipe (33) is connected to the other end of the second flow path (P2) of the refrigerant heat exchanger (22). The other end of the third pipe (33) is connected to a liquid-side line of the second refrigerant circuit (R2). One end of the bypass pipe (34) is connected to an intermediate portion of the first pipe (31). The other end of the bypass pipe (34) is connected to an intermediate portion of the second pipe (32). The first pipe (31) is provided with a first on-off valve (35) between a connecting portion with the bypass pipe (34) and the fifth flow path (P5). The bypass pipe (34) is provided with a second on-off valve (36).

[0050] The hot water supply unit (20) includes part of the water circuit (W). The hot water supply unit (20) has the first water heat exchanger (23) and the second water heat exchanger (26) described above, and also a pump (40), a tank (41), and an internal heat exchanger (42) as components of the water circuit (W).

[0051] The pump (40) circulates water in the water circuit (W). In FIG. 1, the circulation direction of water in the water circuit (W) is indicated by the arrows.

[0052] The tank (41) stores water (or more precisely, hot water) supplied to the target. The tank (41) is a hollow container and contains a hot water storage space (41a). The tank (41) is connected with a water supply pipe (43) and a hot water discharge pipe (44). One end of the water supply pipe (43) is connected to a bottom portion of the tank (41), and the other end of the water supply pipe (43) is connected to a water pipe. When the amount of water in the tank (41) decreases, the water supply pipe (43) supplies low-temperature water in the water pipe to the tank (41). One end of the hot water discharge pipe (44) is connected to an upper portion of the tank (41), and the other end of the hot water discharge pipe (44) is connected to a predetermined target of hot water supply. The hot water discharge pipe (44) supplies high-temperature water in the tank (41) to the target of hot water supply such as a faucet, a shower, or a bathtub.

[0053] The internal heat exchanger (42) is disposed in the hot water storage space (41a). The internal heat exchanger (42) of this embodiment is a heat transfer tube formed in a helical shape. Warm water heated in the first water heat exchanger (23) and the second water heat exchanger (26) flows in the internal heat exchanger (42). The internal heat exchanger (42) exchanges heat between the hot water flowing therein and the water therearound. As a result, the water in the hot water storage space (41a) is heated by the internal heat exchanger (42). In this manner, the tank (41) of this embodiment stores water indirectly heated by the first refrigerant of the first water heat exchanger (23).

[0054] The water circuit (W) has a main flow path (50), a hot water supply-side flow path (51), and a heat-side flow path (52). An outflow end of the main flow path (50) is connected with an inflow end of the hot water supply-side flow path (51) and an inflow end of the heat-side flow path (52). The water circuit (W) is connected with a three-way valve (53). The three-way valve (53) switches between a first state to communicate the main flow path (50) and the hot water supply-side flow path (51) with each other and a second state to communicate the main flow path (50) and the heat-side flow path (52) with each other.

[0055] The main flow path (50) is connected with the pump (40), the fourth flow path (P4) of the first water heat exchanger (23), and the sixth flow path (P6) of the second water heat exchanger (26) in sequence.

[0056] The hot water supply-side flow path (51) has an inflow pipe (51a) and an outflow pipe (51b). The internal heat exchanger (42) is connected between the inflow pipe (51a) and the outflow pipe (51b).

[0057] The heat-side flow path (52) is connected with a utilization-side heat exchanger (6) of the heating device (5). The utilization-side heat exchanger (6) heats air in a target space (an indoor space). The utilization-side heat exchanger (6) is configured as a fin-and-tube heat exchanger or a radiant panel. The utilization-side heat exchanger (6) is configured as an air heat exchanger that directly heats air in the target space, or a floor heating heat exchanger that heats a floor of the target space.

[0058] The hot water supply unit (20) has a supply pipe (52a) and a return pipe (52b) as part of the elements of the heat-side flow path (52). The supply pipe (52a) is a flow path to supply the hot water heated in the first water heat exchanger (23) and the second water heat exchanger (26) to the utilization-side heat exchanger (6). The return pipe (52b) is a flow path to return the water having dissipated heat in the utilization-side heat exchanger (6) to the main flow path (50).

[0059] The hot water supply unit (20) also has a heater unit (54) and an expansion tank (55) as components of the water circuit (W). The heater unit (54) is provided on the main flow path (50) and heats water in the water circuit (W) as an auxiliary unit. The expansion tank (55) communicates with the main flow path (50) and reduces an increase in water pressure in the water circuit (W).(2) Structure of Hot Water Supply Unit

[0060] A structure of the hot water supply unit (20) will be described with reference to FIGS. 1 to 5. In the following description, the terms such as "top," "bottom," "front," "back," "right," and "left" refer to the directions of the arrows in FIG. 2.(2-1) Casing

[0061] As shown in FIG. 2, the hot water supply system (1) has a casing (60) disposed in an indoor space (I). The indoor space (I) is a space formed in a building, and includes not only a living space but also a non-living space, such as a corridor, a basement, a warehouse, or a garage. The casing (60) is placed on the floor surface of the indoor space (I). The casing (60) has a hollow box shape. The casing (60) has a rectangular parallelepiped outer shape. The height of the casing (60) in the top-bottom direction is greater than the length of the casing (60) in the front-back direction and the width of the casing (60) in the left-right direction. The casing (60) includes a top plate (61), a bottom plate (62), a front plate (63), a back plate (64), a right plate (65), and a left plate (66). The top plate (61) forms an upper surface of the casing (60), and the bottom plate (62) forms a lower surface of the casing (60). The front plate (63) forms a front surface, a first side surface of the casing (60), and the back plate (64) forms a back surface, a second side surface of the casing (60). The right plate (65) forms a right surface, a third side surface of the casing (60), and the left plate (66) forms a left surface, a fourth side surface of the casing (60).

[0062] A partition plate (67) is provided in the casing (60). The partition plate (67) partitions the internal space of the casing (60) into the upper space and the lower space. Specifically, the partition plate (67) separates the internal space of the casing (60) into a first space (S1) and a second space (S2). The first space (S1) is formed in an upper portion of the casing (60). The second space (S2) extends from an intermediate portion to a lower portion of the casing (60). The first space (S1) and the second space (S2) have a rectangular parallelepiped shape. The height of the second space (S2) is greater than the height of the first space (S1). The tank (41) is disposed in the second space (S2). In other words, the tank (41) is placed on the bottom plate (62) of the casing (60).

[0063] When the casing (60) is placed, a working space (S3) is secured in front of the casing (60). A first access opening (A1) is formed in an upper portion of the front plate (63) of the casing (60). A first opening / closing cover (68) as part of the front plate (63) is detachably attached to the first access opening (A1). The operator can access the first space (S1) in the casing (60) from the working space (S3) through the first access opening (A1).

[0064] As shown in FIG. 4, a second access opening (A2) is formed in the top plate (61). A second opening / closing cover (69) as part of the top plate (61) is detachably attached to the second access opening (A2). The operator can access the first space (S1) in the casing (60) from the working space (S3) through the second access opening (A2). A structure of the second opening / closing cover (69) will be described in detail later.(2-2) Layout of Each Component in First Space

[0065] FIG. 3 shows the layout of each component including a refrigerant unit (U) and an electric component unit (71). FIG. 3 schematically shows pipes that connect the components, and connecting portions between these pipes. Thus, the positions and shapes of these pipes and connecting portions are not limited to those shown in FIG. 3.

[0066] Each component of the hot water supply unit (20) is disposed in the first space (S1). As shown in FIG. 3, the refrigerant unit (U) having the first refrigerant circuit (R1) is disposed in the first space (S1). The refrigerant unit (U) includes the entire part of the first refrigerant circuit (R1) as a closed circuit. The refrigerant unit (U) has the first compressor (21), the refrigerant heat exchanger (22), the first expansion valve (24), and the first water heat exchanger (23) as components of the first refrigerant circuit (R1).

[0067] The refrigerant unit (U) is closer to the front plate (63) than to the back plate (64). The refrigerant unit (U) is closer to the left plate (66) than to the right plate (65). The first compressor (21) is disposed near the first access opening (A1). The first compressor (21) is positioned so that it can be seen from the outside of the casing (60) through the first access opening (A1) when the first opening / closing cover (68) is removed. The refrigerant unit (U) is located above the tank (41). The refrigerant unit (U) overlaps with the tank (41) in the vertical direction.

[0068] The refrigerant heat exchanger (22) and the first water heat exchanger (23) are disposed behind the first compressor (21). In this embodiment, the refrigerant heat exchanger (22) is disposed to the right of the first water heat exchanger (23). The first expansion valve (24) is disposed between the refrigerant heat exchanger (22) and the first compressor (21) or between the first water heat exchanger (23) and the first compressor (21).

[0069] The hot water supply unit (20) has a support (70) that supports the refrigerant unit (U). The support (70) is located below the refrigerant unit (U) and supports the support (70) from below. The support (70) can be pulled out from the first access opening (A1) along the bottom plate (62). The bottom plate (62) is provided with a guide member that guides the support (70) in the front-back direction in one preferred embodiment. A structure of the support (70) will be described in detail later.

[0070] The electric component unit (71) is provided in the first space (S1). The electric component unit (71) is disposed above the tank (41). The electric component unit (71) overlaps with the tank (41) in the vertical direction.

[0071] The electric component unit (71) includes a control board for controlling each component of the hot water supply unit (20). The electric component unit (71) is disposed near the first access opening (A1). The electric component unit (71) is positioned so that it can be seen from the outside of the casing (60) through the first access opening (A1) when the first opening / closing cover (68) is removed.

[0072] The second water heat exchanger (26) is disposed behind the electric component unit (71). The first on-off valve (35) and the second on-off valve (36) are disposed between the second water heat exchanger (26) and the electric component unit (71). The first pipe (31) and the third pipe (33) as refrigerant pipes are disposed around the second water heat exchanger (26). The first pipe (31) and the third pipe (33) extend in the vertical direction in the first space (S1).

[0073] The first space (S1) has a connection space (75) formed behind the electric component unit (71). The connection space (75) is formed in the front side of the first space (S1). A first connecting portion (C1), a second connecting portion (C2), a third connecting portion (C3), and a fourth connecting portion (C4) are disposed in the connection space (75).

[0074] The first connecting portion (C1) and the second connecting portion (C2) form water-side connecting portions which can detachably connect the first water heat exchanger (23) and the water circuit (W). As shown in FIG. 1, the first connecting portion (C1) connects the outflow-side water pipe of the fourth flow path (P4) of the first water heat exchanger (23) and the water circuit (W). The second connecting portion (C2) connects the inflow-side water pipe of the fourth flow path (P4) of the first water heat exchanger (23) and the water circuit (W). The third connecting portion (C3) and the fourth connecting portion (C4) form heating medium-side connecting portions which can detachably connect the refrigerant heat exchanger (22) and the second refrigerant circuit (R2). The third connecting portion (C3) connects the gas-side refrigerant pipe of the second flow path (P2) of the refrigerant heat exchanger (22) and the second refrigerant circuit (R2). The fourth connecting portion (C4) connects the liquid-side refrigerant pipe of the second flow path (P2) of the refrigerant heat exchanger (22) and the second refrigerant circuit (R2). The first connecting portion (C1) and the second connecting portion (C2) may connect the first water heat exchanger (23) and the water circuit (W) directly, or may connect the first water heat exchanger (23) and the water circuit (W) indirectly via pipes. The third connecting portion (C3) and the fourth connecting portion (C4) may connect the refrigerant heat exchanger (22) and the second refrigerant circuit (R2) directly, or may connect the refrigerant heat exchanger (22) and the second refrigerant circuit (R2) indirectly via pipes.

[0075] The refrigerant unit (U) is closer to the front plate (63) than the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) are. The refrigerant unit (U) is positioned not to overlap in the front-back direction with the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4).

[0076] A water circuit-side space (76) in which the components of the water circuit (W) are disposed is formed in the rear side of the first space (S1). The pump (40), the heater unit (54), the three-way valve (53), and the expansion tank (55) are disposed in the water circuit-side space (76). The inflow pipe (51a), the outflow pipe (51b), the supply pipe (52a), and the return pipe (52b) are disposed as water pipes in the water circuit-side space (76).

[0077] The supply pipe (52a) and the return pipe (52b) run through the top plate (61) and are connected to the water pipes outside the casing (60). The inflow pipe (51a) and the outflow pipe (51b) run through the partition plate (67) and are connected to the internal heat exchanger (42).

[0078] The first pipe (31), the second pipe (32), and the third pipe (33) are disposed in the first space (S1). The other end-side part of the first pipe (31) extends backward along the right plate (65). The second pipe (32) is disposed in an intermediate portion of the first space (S1) in the front-back direction and extends in the left-right direction from the refrigerant heat exchanger (22) to the second heat exchanger (22). The other end-side part of the third pipe (33) extends backward along the right plate (65).

[0079] Although not shown, other components of the water circuit (W) are disposed in the first space (S1). The other components include a drainage valve, a ball valve, a flow rate sensor, and a filter. The other components are positioned closer to the front plate (63) than to the back plate (64) in one preferred embodiment.(2-3) Connecting Portions on Top Plate and Peripheral Structure

[0080] As shown in FIG. 2 and FIG. 4, the top plate (61) is provided with a first refrigerant joint (81), a second refrigerant joint (82), a first water joint (83), a second water joint (84), a third water joint (85), and a fourth water joint (86). These joints are located outside the casing (60). These joints couple the pipes in the casing (60) with the pipes outside the casing (60).

[0081] Specifically, the lower end of the first refrigerant joint (81) is connected with the third pipe (33), and the lower end of the second refrigerant joint (82) is connected with the first pipe (31). The lower end of the first water joint (83) is connected with the supply pipe (52a), the lower end of the second water joint (84) is connected with the return pipe (52b), the lower end of the third water joint (85) is connected with the water supply pipe (43), and the lower end of the fourth water joint (86) is connected with the hot water discharge pipe (44).

[0082] After installing the casing (60) in the indoor space (I), the operator connects the joints with the pipes outside the casing (60). Specifically, the upper end of the first refrigerant joint (81) is connected with a first connection pipe (91) coupled with the outdoor unit (10) and located on the liquid side. The upper end of the second refrigerant joint (82) is connected with a second connection pipe (92) coupled with the outdoor unit (10) and located on the gas side. The upper end of the first water joint (83) is connected with a third water pipe (95) of the heating device (5) that is located on the inflow side. The upper end of the second water joint (84) is connected with a fourth water pipe (96) of the heating device (5) that is located on the outflow side. The upper end of the third water joint (85) is connected with a first water pipe (93) for water supply. The upper end of the fourth water joint (86) is connected with a second water pipe (94) for hot water supply.

[0083] The first water joint (83), the second water joint (84), the third water joint (85), and the fourth water joint (86) form first outer connecting portions, and the first refrigerant joint (81) and the second refrigerant joint (82) form second outer connecting portions.

[0084] In this embodiment, the first outer connecting portions (83, 84, 85, 86) and the second outer connecting portions (81, 82) are arranged in the left-right direction along the back plate (64). The second access opening (A2) is formed in front of the first outer connecting portions (83, 84, 85, 86) and the second outer connecting portions (81, 82). The second access opening (A2) is formed from near the first outer connecting portions (83, 84, 85, 86) and the second outer connecting portions (81, 82) to the front plate (63).

[0085] The second opening / closing cover (69) opens and closes the second access opening (A2). A rear frame (F) extending in the left-right direction is formed behind the second opening / closing cover (69). The first outer connecting portions (83, 84, 85, 86) and the second outer connecting portions (81, 82) are formed between the rear frame (F) and the second opening / closing cover (69). Specifically, the rear frame (F) and the second opening / closing cover (69) form holes in the positions corresponding to the joints (81, 82, 83, 84, 85, 86). In this embodiment, each of the front edge of the rear frame (F) and the rear edge of the second opening / closing cover (69) has arc-shaped grooves, and these grooves form the holes through which the joints (81, 82, 83, 84, 85, 86) or the pipes pass. Only one of the rear frame (F) or the second opening / closing cover (69) may have the grooves that form the holes.(2-4) Configuration for Response to Leakage of Refrigerant

[0086] As shown in FIG. 5, the support (70) of this embodiment forms an inner casing that houses the refrigerant unit (U). The support (70) has a rectangular parallelepiped box shape. The components of the refrigerant unit (U) such as the compressor (21) and others are placed on the bottom surface of the support (70). An opening (70a) is formed in a sidewall of the support (70). The opening (70a) allows the inside of the support (70) and the outside of the support (70) to communicate with each other. The opening (70a) is formed in the left sidewall of the support (70), but may be formed in the front sidewall, the rear sidewall, or the right sidewall. The opening (70a) is formed in a lower portion of the support (70), or more precisely, at a position along the bottom portion of the support (70). The opening (70a) is configured as a long hole that extends in the front-back direction. The opening (70a) may be a circular hole.

[0087] The partition plate (67) of this embodiment has a partition plate body (67a) on which the refrigerant unit (U) is placed and step portions (67b) which are recessed downward from the outer edge of the partition plate body (67a). The partition plate (67) of this embodiment has the step portion (67b) on both the left and right sides of the partition plate body (67a). A relay groove (77) is defined by the inside of the step portion (67b). The relay groove (77) has a rectangular shape when viewed in the cross section orthogonal to the front-back direction. The relay groove (77) extends in the front-back direction along the opening (70a). The relay groove (77) forms part of the first space (S1).

[0088] The casing (60) has communication paths (78) that allow the first space (S1) and the indoor space (I) located outside the casing (60) to communicate with each other. The communication path (78) is open toward the indoor space (I). The communication path (78) of this embodiment is formed in both the left plate (66) and the right plate (65). The communication path (78) is located at the same level as the relay groove (77) and is directly connected to the relay groove (77). The refrigerant unit (U) and the electric component unit (71) are located at higher positions than the communication path (78).

[0089] The hot water supply unit (20) has a refrigerant sensor (79) that detects leakage of a refrigerant. In this embodiment, the refrigerant sensor (79) is disposed near the opening (70a). More precisely, the refrigerant sensor (79) is distanced 10 cm or less away from the opening (70a).(2-5) Controller and Alerting Device

[0090] As schematically shown in FIG. 1, the hot water supply unit (20) has a controller (120) and an alerting device (121). The controller (120) includes a microcomputer and a memory device. The memory device stores software for operating the microcomputer. The controller (120) receives detection signals from the refrigerant sensor (79).

[0091] The alerting device (121) is an example of a device for response to leakage of a refrigerant. The alerting device (121) provides the user with first information on leakage of a refrigerant through sounds or light. If the concentration of a refrigerant detected by the refrigerant sensor (79) is higher than or equal to a predetermined value, the controller (120) instructs the alerting device (121) to release the first information.(3) Operation

[0092] In the operation of the hot water supply system (1), the second refrigerant circuit (R2) performs a subcritical cycle or a supercritical cycle, and at the same time the first refrigerant circuit (R1) performs a subcritical cycle. The second refrigerant circuit (R2) selectively performs a first operation and a second operation. The water circuit (W) selectively performs a third operation or a fourth operation.

[0093] In the first operation, the four-way switching valve (14) turns into the first state, the first on-off valve (35) turns into the open state, and the second on-off valve (36) turns into the closed state. In the first operation, the refrigerant compressed by the second compressor (11) dissipates heat in the second water heat exchanger (26) and the refrigerant heat exchanger (22), then is decompressed by the second expansion valve (13), and then evaporates in the outdoor heat exchanger (12).

[0094] In the second operation, the four-way switching valve (14) turns into the first state, the first on-off valve (35) turns into the closed state, and the second on-off valve (36) turns into the open state. In the first operation, the refrigerant compressed by the second compressor (11) bypasses the second water heat exchanger (26), then dissipates heat in the refrigerant heat exchanger (22), then is decompressed by the second expansion valve (13), and then evaporates in the outdoor heat exchanger (12).

[0095] In the first refrigerant circuit (R1), the refrigerant compressed by the first compressor (21) dissipates heat in the first water heat exchanger (23), then is decompressed by the first expansion valve (24), and then evaporates in the refrigerant heat exchanger (22).

[0096] In the third operation, the three-way valve (53) turns into the first state. In the third operation, the water transported by the pump (40) is heated by only the first water heat exchanger (23) or both the second water heat exchanger (26) and the first water heat exchanger (23). The heated water dissipates heat to the water in the hot water storage space (41a) in the internal heat exchanger (42). As a result, hot water is produced in the tank (41).

[0097] In the fourth operation, the three-way valve (53) turns into the second state. In the fourth operation, the water transported by the pump (40) is heated by only the first water heat exchanger (23) or both the second water heat exchanger (26) and the first water heat exchanger (23). The heated water dissipates heat to the air in the target space in the utilization-side heat exchanger (6) of the heating device (5), and as a result, the target space is heated.(4) Operator's Operation

[0098] To ship out and transport the hot water supply unit (20), the operator moves the refrigerant unit (U) and the casing (60) separately. This is because if the hot water supply unit (20) is transported while the refrigerant unit (U) is disposed in the first space (S1) of the casing (60), the center of gravity of the hot water supply unit (20) is positioned higher and it is difficult to conduct the transporting operation and the installing operation. The operator can transport the refrigerant unit (U) separate from the casing (60) with the support (70).

[0099] Next, the operator loads the refrigerant unit (U) and the support (70) into the casing (60). Specifically, the operator loads the support (70) that supports the refrigerant unit (U) from the working space (S3) to the first space (S1) through the first access opening (A1).

[0100] The operator connects the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) through the first access opening (A1). Accordingly, the refrigerant unit (U) is connected with the water circuit (W) and the second refrigerant circuit (R2). The first refrigerant circuit (R1) may be filled with a refrigerant before the transporting operation or may be at the installing operation.

[0101] The operator connects the pipes to the joints on the top plate (61). Specifically, the operator connects the first connection pipe (91) to the first refrigerant joint (81), and the second connection pipe (92) to the second refrigerant joint (82). The operator connects each of the water pipes (93, 94, 95, 96) to the associated one of the water joints (83, 84, 85, 86).

[0102] The operator can detach the second opening / closing cover (69) on the top plate (61) while the pipes are connected to the joints (81, 82, 83, 84, 85, 86). This is because as shown in FIG. 4, the pipes (91, 92, 93, 94, 95, 96) are located in the grooves between the second opening / closing cover (69) and the rear frame (F). Accordingly, the operator can connect or disconnect the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) through the second access opening (A2).

[0103] The operator can do maintenance of the refrigerant unit (U) after unloading the refrigerant unit (U) to the outside of the casing (60). Specifically, the operator in the working space (S3) detaches the first opening / closing cover (68) from the casing (60) to expose the first access opening (A1). The operator disconnects the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) through the first access opening (A1). As a result, the refrigerant unit (U) is detached from the water circuit (W) and the second refrigerant circuit (R2). Also in this state, the first refrigerant circuit (R1) of the refrigerant unit (U) remains a closed circuit, and thus the risk that a flammable refrigerant may leak from the first refrigerant circuit (R1) is smaller than when the refrigerant unit (U) is detached in the first refrigerant circuit (R1). Since the refrigerant in the second refrigerant circuit (R2) is carbon dioxide, no significant problem occurs even if the refrigerant leaks from the second refrigerant circuit (R2).

[0104] The operator moves the support (70) forward through the first access opening (A1). Accordingly, it is possible to unload the refrigerant unit (U) and the support (70) to the outside of the casing (60) together through the first access opening (A1). The refrigerant unit (U) is located closer to the front plate (63) than the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4) are. Accordingly, it is possible to reduce the refrigerant unit (U) interfering with these connecting portions, and thus it is possible to unload the refrigerant unit (U) easily.

[0105] The operator performs maintenance of the removed refrigerant unit (U) not in the indoor space (I) but in the outdoor space. Accordingly, even if a flammable refrigerant leaks from the first refrigerant circuit (R1), it is possible to reduce the problems resulting from this leakage. After completing the maintenance of the refrigerant unit (U), the operator returns the refrigerant unit (U) and the support (70) to the original positions together. Then, the operator reconnects the first connecting portion (C1), the second connecting portion (C2), the third connecting portion (C3), and the fourth connecting portion (C4).(5) Operation at Leakage of Refrigerant

[0106] The operation at leakage of a refrigerant will be described. FIG. 5 shows the leaked refrigerant by the broken arrows. If a refrigerant leaks from the first refrigerant circuit (R1), this refrigerant accumulates in the support (70). The refrigerant in the support (70) discharges into the first space (S1) (or more precisely, the space between the casing (60) and the support (70)). The refrigerant in the first space (S1) flows down to the relay groove (77) inside the step portion (67b). The refrigerant in the relay groove (77) discharges to the outside of the casing (60) through the communication path (78) of the casing (60).

[0107] Since the refrigerant unit (U) is located above the tank (41), the refrigerant having flowed out from the first refrigerant circuit (R1) is also located at a high position. Accordingly, the distance the refrigerant must travel to reach the height of the bottom plate (62) of the casing (60) becomes longer. Accordingly, the refrigerant having flowed out of the communication path (78) diffuses before reaching the floor of the indoor space (I). As a result, it is possible to reduce the concentration of the refrigerant. In particular, when falling downward, the refrigerant diffuses in the horizontal direction, and thus it is possible to reduce the concentration of the refrigerant near the floor surface. Accordingly, it is possible to prevent the concentration of the refrigerant from reaching the lower flammable limit (LFL).

[0108] Since the communication path (78) is located at a lower position than the refrigerant unit (U), it is possible to reliably guide the flammable refrigerant having a higher specific gravity than air to the communication path (78).

[0109] The support (70), which is the inner casing, houses the refrigerant unit (U). Accordingly, it is possible to delay the time required for the refrigerant to discharge to the outside of the casing (60) through the communication path (78). Accordingly, it is possible to limit the amount of a refrigerant flowing out from the communication path (78), and thus it is possible to lower the concentration of the refrigerant in the indoor space (I).

[0110] The refrigerant sensor (79) is disposed near the opening (70a). Accordingly, the refrigerant sensor (79) can detect leakage of a refrigerant immediately. In particular, the refrigerant sensor (79) is located on the flow path between the opening (70a) and the communication path (78), and thus the refrigerant sensor (79) can detect leakage of a refrigerant immediately. If the refrigerant sensor (79) detects leakage of a refrigerant, the controller (120) instructs the alerting device (121) to release the first information. Accordingly, the user can respond to the leakage of a refrigerant immediately.(6) Advantages of Embodiment(6-1)

[0111] The refrigerant unit (U) is disposed above the tank (41). According to this configuration, the refrigerant unit (U) is located at a high position. Accordingly, the refrigerant having leaked from the refrigerant unit (U) gradually diffuses in the air before reaching the floor surface of the indoor space (I). Accordingly, it is possible to reduce the concentration of the leaked refrigerant.(6-2)

[0112] The casing (60) has the first side surface (63) having the first access opening (A1) of the first space (S1) which houses the refrigerant unit (U) and the second side surface (64) located opposite to the first side surface (63) in the casing (60). The hot water supply unit further includes the support (70) that supports the refrigerant unit (U) and that can be loaded and unloaded through the first access opening (A1).

[0113] According to this configuration, by moving the support (70) to the outside of the casing (60) through the first access opening (A1), it is possible to unload the refrigerant unit (U) to the outside of the casing (60). Accordingly, the operator can perform a predetermined operation while the refrigerant unit (U) is unloaded to the outdoor space, and thus it is possible to reduce the risk that the first refrigerant, a flammable refrigerant, may leak.

[0114] In addition, the operator can move the refrigerant unit (U) and the casing (60) separately while the refrigerant unit (U) is unloaded to the outside the casing (60). If the hot water supply unit (20) is transported while the refrigerant unit (U) is placed in the casing (60), the center of gravity of the hot water supply unit (20) is positioned higher. This is because the refrigerant unit (U) is located above the tank (41) and, during transportation, the tank (41) does not store water. In contrast, if the refrigerant unit (U) and the casing (60) are transported separately, the center of gravity of the casing (60) is positioned lower during transportation. Accordingly, it is possible to transport the hot water supply unit (20) easily.(6-3)

[0115] The refrigerant unit (U) has the water-side connecting portions (C1, C2) that detachably connect the refrigerant heat exchanger (22) and the water circuit (W), and the heating medium-side connecting portions (C3, C4) that detachably connect the first water heat exchanger (23) and the second refrigerant circuit (R2).

[0116] According to this configuration, by disconnecting the water-side connecting portions (C1, C2), it is possible to detach the first water heat exchanger (23) from the water circuit (W). By disconnecting the heating medium-side connecting portions (C3, C4), it is possible to detach the refrigerant heat exchanger (22) from the second refrigerant circuit (R2). As a result, the refrigerant unit (U) detached from the water circuit (W) and the second refrigerant circuit (R2) can be unloaded to the outside of the casing (60) through the first access opening (A1).(6-4)

[0117] The refrigerant unit (U) is closer to the first side surface (63) than the water-side connecting portions (C1, C2) and the heating medium-side connecting portions (C3, C4) are. In particular, the refrigerant unit (U) does not overlap in the front-back direction with the water-side connecting portions (C1, C2) and the heating medium-side connecting portions (C3, C4). According to this configuration, it is possible to load and unload the refrigerant unit (U) easily.(6-5)

[0118] The casing (60) has the top plate (61) having the second access opening (A2) of the first space (S1). According to this configuration, the operator can access the water-side connecting portions (C1, C2) and the heating medium-side connecting portions (C3, C4) from above the casing (60) through the second access opening (A2).(6-6)

[0119] Further, the first outer connecting portions (83, 84, 85, 86) provided on the top plate (61) of the casing (60) and connected with the water pipes (93, 94, 95, 96) of the water circuit (W) extending from the outside of the casing (60) are provided, and also the second outer connecting portions (81, 82) provided on the top plate (61) of the casing (60) and connected with the refrigerant pipes (91, 92) of the second refrigerant circuit (R2) extending from the outside of the casing (60) are provided.

[0120] According to this configuration, the distance from the first water heat exchanger (23) to the first outer connecting portions (83, 84, 85, 86) and the distance from the refrigerant heat exchanger (22) to the second outer connecting portions (81, 82) are shortened. Accordingly, it is possible to shorten the pipe length from the first water heat exchanger (23) to the first outer connecting portions (83, 84, 85, 86) and the pipe length from the refrigerant heat exchanger (22) to the second outer connecting portions (81, 82).(6-7)

[0121] The casing (60) has the communication path (78) that allows the indoor space (I) to communicate with the first space (S1) that houses the refrigerant unit (U). According to this configuration, when a refrigerant leaks from the first refrigerant circuit (R1) of the refrigerant unit (U), it is possible to discharge this refrigerant from the first space (S1) to the indoor space (I) located outside the casing (60) through the communication paths (78). As a result, it is possible to accelerate diffusion of the refrigerant before the refrigerant drops onto the floor surface, and thus it is possible to reduce the concentration of the refrigerant.

[0122] The communication paths (78) are located at lower positions than the refrigerant unit (U). According to this configuration, the communication paths (78) are formed at a lower position than the refrigerant unit (U), and thus it is easier to guide the refrigerant having leaked from the refrigerant circuit (R1) to the communication path (78). Accordingly, it is possible to accelerate diffusion of the refrigerant outside the casing (60). The refrigerant unit (U) and the electric component unit (71) are located at higher positions than the communication paths (78). Accordingly, the refrigerant unit (U) and the electric component unit (71) are less affected by the leaked refrigerant.

[0123] The hot water supply unit (20) further includes the inner casing (70) disposed in the first space (S1) and housing the refrigerant unit (U). The inner casing (70) has the opening (70a) that allows the outside and the inside of the inner casing (70) to communicate with each other. According to this configuration, it is possible to reduce the speed at which a refrigerant discharges to the outside of the casing (60), and thus it is possible to reduce the concentration of the refrigerant outside the casing (60).

[0124] The refrigerant sensor (79) is disposed in the inner casing (70) or near the opening (70a). According to this configuration, the refrigerant sensor (79) can detect leakage of a refrigerant immediately.(7) Variations

[0125] The above embodiment may be modified as the following variations. In the following, the differences from the above embodiment will be described.(7-1) First Variation

[0126] In the first variation shown in FIG. 6, the refrigerant sensor (79) is disposed in the support (70), which is an inner casing. Since the support (70) houses the refrigerant unit (U), the concentration of the refrigerant having leaked in the support (70) increases immediately. By providing the refrigerant sensor (79) in the support (70), it is possible to detect leakage of a refrigerant immediately.

[0127] In particular, in the first variation, by providing the refrigerant sensor (79) near the opening (70a) through which the refrigerant flows, it is possible to detect leakage of a refrigerant immediately. The refrigerant sensor (79) may be disposed on the opening (70a).(7-2) Second Variation

[0128] In the second variation shown in FIG. 7, the refrigerant sensor (79) is disposed near the communication path (78). The distance between the refrigerant sensor (79) and the associated communication path (78) is 10 cm or less. The refrigerant sensor (79) of this variation is located outside the casing (60). However, the refrigerant sensor (79) may be disposed in the casing (60), or may be disposed on the communication path (78). The refrigerant sensor (79) may be disposed on the relay groove (77). According to these configurations, a refrigerant flows around the refrigerant sensor (79) easily, and thus it is possible to detect leakage of a refrigerant immediately.

[0129] In the second variation, the side plates (65, 66) of the casing (60) are provided with guide plates (66a). The guide plates (66a) are formed above the communication path (78). The guide plates (66a) extend obliquely downward from the side plates (65, 66). For example, the guide plate (66a) is formed by lifting part of the side plate that is formed between a pair of slits extending in the vertical direction. The refrigerant sensor (79) is positioned to overlap with the guide plate (66a) in the top-bottom direction and overlap with the communication path (78) in the lateral direction.

[0130] In the second variation shown in FIG. 7, no inner casing is provided. More precisely, the support (70) is formed as a plate that is placed on the partition plate (67) and laid along the partition plate (67). The refrigerant unit (U) is placed on the support (70). According to this configuration, the refrigerant having leaked from the refrigerant unit (U) can be discharged to the outside of the casing (60) immediately, and thus it is possible to reduce the concentration of the refrigerant in the casing (60) immediately.(7-3) Third Variation

[0131] As shown in FIG. 8, the hot water supply unit (20) of the third variation has a shielding member (98). The shielding member (98) is disposed in the front side of the first space (S1). The shielding member (98) is disposed between the refrigerant unit (U) and the connection space (75). The shielding member (98) shields the third connecting portion (C3) and the fourth connecting portion (C4) from the first refrigerant circuit (R1). The shielding member (98) is formed as a plate of which the thickness direction is the left-right direction. In top view, the shielding member (98) extends from near the front end of the casing (60) to an intermediate position of the casing (60) in the front-back direction. The upper end of the shielding member (98) is located at a higher position than the upper end of the first compressor (21). The shielding member (98) of this variation is integrated with the support (70). A lower portion of the shielding member (98) is continuous with the support (70). The shielding member (98) may be separate from the support (70).

[0132] The third connecting portion (C3) and the fourth connecting portion (C4) may be subject to brazing, welding, or others for pipe connection, and may be subject to cutting or others for pipe separation. These operations may cause sparks to fly toward the first refrigerant circuit (R1). Since the shielding member (98) shields the third connecting portion (C3) and the fourth connecting portion (C4) from the first refrigerant circuit (R1), it is possible to reduce sparks flying toward the first refrigerant circuit (R1). As a result, it is possible to reduce the risk that a flammable refrigerant may ignite.(7-4) Fourth Variation

[0133] As shown in FIG. 9, instead of the second refrigerant circuit (R2) of the embodiment, the hot water supply system (1) of the fourth variation has a primary-side circulation circuit (100) as a heating medium circuit. The primary-side circulation circuit (100) is filled with a heating medium such as water or antifreeze solution. The configuration of part of the primary-side circulation circuit (100) that is involved in the hot water supply unit (20) is the same as that of the embodiment. The primary-side circulation circuit (100) has a circulation pump (101) and an underground heat exchanger (102) as components installed in the outdoor space. The circulation pump (101) circulates the heating medium in the primary-side circulation circuit (100). The underground heat exchanger (102) is a heat transfer tube for providing underground heat with the heating medium and has a helical shape, for example. The heating medium heated by the underground heat exchanger (102) dissipates heat in the refrigerant heat exchanger (22) and is used to produce hot water in the tank (41).(8) Other Embodiments

[0134] The hot water supply system (1) may be a system that supplies hot water from the tank (41) only to the heating device (5).

[0135] The hot water supply unit (20) may not have the second water heat exchanger (26). In this case, the second refrigerant circuit (R2) is configured without the second water heat exchanger (26), the bypass pipe (34), the first on-off valve (35), and the second on-off valve (36).

[0136] The water heated by the first water heat exchanger (23) may be accumulated directly in the tank (41). In other words, the tank (41) may store the water directly heated by the first refrigerant.

[0137] The support (70) may have a box shape that houses the refrigerant unit (U). In this case, the side plate of the support (70) may form the shielding member (98) of the first variation.

[0138] The refrigerant unit (U) and the electric component unit (71) do not necessarily overlap with the tank (41) in the vertical direction. The refrigerant unit (U) and the electric component unit (71) only need to be located at higher positions than the upper end of the tank (41).

[0139] The heating medium-side connecting portions (C3, C4) and the water-side connecting portions (C1, C2) may be provided on a side surface of the casing (60).

[0140] The expansion mechanism may be not an expansion valve but a capillary tube or an expansion device.

[0141] The communication path (78) may be a gap formed between frames or plates of the casing (60). The communication path (78) may be located at a higher position than the refrigerant unit (U). The hot water supply unit (20) may have an inner casing that is separate from the support (70) and that houses the refrigerant unit (U).

[0142] A device activated in response to detection of leakage of a refrigerant may be a shutoff valve that opens and closes the refrigerant circuit (R1), a fan that stirs the air, or a ventilating device that operates for the indoor space (I).(9) Other Descriptions

[0143] While the embodiments and variations thereof have been described above, it will be understood that various changes in form and details may be made without departing from the spirit and scope of the claims. The embodiments, the variations, and the other embodiments may be combined and replaced with each other as long as the functions of the target of the present disclosure are not impaired.

[0144] The expressions such as "first," "second," "third," . . . , described above are used to distinguish the terms to which these expressions are given, and do not limit the number and order of the terms.INDUSTRIAL APPLICABILITY

[0145] As described above, the present disclosure is useful for a hot water supply unit.DESCRIPTION OF REFERENCE CHARACTERS

[0146] 20Hot Water Supply Unit 21First Compressor (Compressor) 22Refrigerant Heat Exchanger (Second Heat Exchanger) 23First Water Heat Exchanger (First Heat Exchanger) 24First Expansion Valve (Decompression Mechanism) 41Tank 60Casing 61Top Plate (Upper Surface) 63Front Plate (First Side Surface) 64Back Plate (Second Side Surface) 70Support (Inner Casing) 70aOpening 71Electric Component Unit 78Communication Path 79Refrigerant Sensor 81, 82Second Outer Connecting Portion 83, 84, 85, 86First Outer Connecting Portion 91, 92Refrigerant Pipe 93, 94, 95, 96Water Pipe 98Shielding Member A1First Access Opening A2Second Access Opening C1, C2Water-Side Connecting Portion C3, C4Heating Medium-Side Connecting Portion IIndoor Space R1First Refrigerant Circuit (Refrigerant Circuit) R2Second Refrigerant Circuit R2, 100Heating Medium Circuit S1First Space URefrigerant Unit WWater Circuit

Examples

Embodiment Construction

[0041]Embodiments of the present disclosure will be described in detail below with reference to the drawings. The present disclosure is not limited to the embodiments shown below, and various changes can be made within the scope without departing from the technical concept of the present disclosure. Since each of the drawings is intended to illustrate the present disclosure conceptually, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.

(1) Configuration of Hot Water Supply System

(1-1) General Configuration

[0042]A hot water supply system (1) supplies hot water to a target. The target of this embodiment includes a target of hot water supply, such as a faucet, a shower, or a bathtub, and also a heating device (5) using hot water. The hot water supply system (1) is connected to the target of hot water supply and the heating device (5) via water pipes. The hot water supply system (1) has an outdoor unit (10) disposed outdoors and a ho...

Claims

1. A hot water supply unit comprising: a refrigerant unit (U) having a refrigerant circuit (R1) configured to perform a refrigeration cycle by using a first refrigerant that is a flammable refrigerant; a tank (41) configured to store water directly or indirectly heated by the first refrigerant; and a casing (60) housing the refrigerant unit (U) and the tank (41) and disposed in an indoor space (I), wherein the refrigerant circuit (R1) has a compressor (21), a first heat exchanger (23) configured to exchange heat between the first refrigerant in the refrigerant circuit (R1) and water in a water circuit (W), a decompression mechanism (24), and a second heat exchanger (22) configured to exchange heat between the first refrigerant in the refrigerant circuit (R1) and a heating medium in a heating medium circuit (R2, 100), and the refrigerant unit (U) is disposed above the tank (41).

2. The hot water supply unit of claim 1, wherein the casing (60) has a first side surface (63) having a first access opening (A1) of a first space (S1) that houses the refrigerant unit (U), and a second side surface (64) located opposite to the first side surface (63) in the casing (60), and the hot water supply unit further includes a support (70) that supports the refrigerant unit (U) and that can be loaded and unloaded through the first access opening (A1).

3. The hot water supply unit of claim 2, wherein the refrigerant unit (U) has a water-side connecting portion (C1, C2) configured to detachably connect the first heat exchanger (23) and the water circuit (W), and a heating medium-side connecting portion (C3, C4) configured to detachably connect the second heat exchanger (22) and the heating medium circuit (R2, 100).

4. The hot water supply unit of claim 3, wherein the refrigerant unit (U) is closer to the first side surface (63) than the water-side connecting portion (C1, C2) and the heating medium-side connecting portion (C3, C4) are.

5. The hot water supply unit of claim 4, wherein the casing (60) has an upper surface (61) having a second access opening (A2) of the first space (S1).

6. The hot water supply unit of any one of claims 1 to 5, further comprising: a first outer connecting portion (83, 84, 85, 86) provided on the upper surface (61) of the casing (60) and connected with a water pipe (93, 94, 95, 96) of the water circuit (W) extending from an outside of the casing (60).

7. The hot water supply unit of claim 6, wherein the casing (60) has a first side surface (63) having a first access opening (A1) of a first space (S1) that houses the refrigerant unit (U), and a second side surface (64) located opposite to the first side surface (63) in the casing (60), and the first outer connecting portion (83, 84, 85, 86) is closer to the second side surface (64) than to the first side surface (63).

8. The hot water supply unit of any one of claims 1 to 7, further comprising: a second outer connecting portion (81, 82) provided on the upper surface (61) of the casing (60) and connected with a refrigerant pipe (91, 92) of the heating medium circuit (R2, 100) extending from an outside of the casing (60).

9. The hot water supply unit of claim 8, wherein the casing (60) has a first side surface (63) having a first access opening (A1) of a first space (S1) that houses the refrigerant unit (U), and a second side surface (64) located opposite to the first side surface (63) in the casing (60), and the second outer connecting portion (81, 82) is closer to the second side surface (64) than to the first side surface (63).

10. The hot water supply unit of any one of claims 1 to 9, wherein the casing (60) has a communication path (78) that allows the indoor space (I) to communicate with the first space (S1) that houses the refrigerant unit (U).

11. The hot water supply unit of claim 10, wherein the communication path (78) is located at a lower position than the refrigerant unit (U).

12. The hot water supply unit of claim 10 or 11, further comprising: a refrigerant sensor (79) configured to detect leakage of the first refrigerant, wherein the refrigerant sensor (79) is disposed on the communication path (78) or near the communication path (78).

13. The hot water supply unit of claim 10 or 11, further comprising: an inner casing (70) disposed in the first space (S1) and housing the refrigerant unit (U), wherein the inner casing (70) has an opening (70a) that allows an outside and an inside of the inner casing (70) to communicate with each other.

14. The hot water supply unit of claim 13, further comprising: a refrigerant sensor (79) configured to detect leakage of the first refrigerant, wherein the refrigerant sensor (79) is disposed in the inner casing (70) or near the opening (70a).

15. The hot water supply unit of any one of claims 3 to 5, further comprising: a shielding member (98) configured to shield the heating medium-side connecting portion (C3, C4) and the refrigerant circuit (R1) from each other.

16. The hot water supply unit of any one of claims 1 to 15, further comprising: an electric component unit (71) housed in the casing (60), wherein the electric component unit (71) is disposed above the tank (41).

17. The hot water supply unit of any one of claims 10 to 14, further comprising: an electric component unit (71) housed in the casing (60), wherein the electric component unit (71) is located at a higher position than the communication path (78).

18. The hot water supply unit of any one of claims 1 to 17, wherein the heating medium circuit (R2, 100) is a second refrigerant circuit (R2) configured to perform a refrigeration cycle by using a second refrigerant.

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