Hot water supply unit

Abstract

This hot water supply unit comprises a refrigerant unit (U) having a refrigerant circuit (R1) that performs a refrigeration cycle using a first refrigerant, which is a flammable refrigerant. The refrigerant circuit (R1) has: a compressor (21); a first heat exchanger (23) that exchanges heat between the first refrigerant in the refrigerant circuit (R1) and water in a water circuit (W); a pressure-reducing mechanism (24); and a second heat exchanger (22) that exchanges heat between the first refrigerant in the refrigerant circuit (R1) and a heat medium in a heat medium circuit (R2, 100). The refrigerant unit (U) is disposed above a tank (41).

Description

Hot water supply unit

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

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

[0003] Japanese Patent Application Laid-Open No. 2004-132647

[0004] The inventors of the present application have devised a hot water supply unit including a casing that houses a refrigerant unit having a refrigerant circuit and a tank. The hot water supply unit (casing) is arranged in an indoor space. A flammable refrigerant is used as the refrigerant in the refrigerant circuit. The hot water supply unit is used, for example, for hot water supply and air conditioning. On the other hand, when the hot water supply unit is arranged in an indoor space in this way, the risk of leakage of the flammable refrigerant increases.

[0005] An object of the present disclosure is to reduce the risk of leakage of a flammable refrigerant.

[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) that performs a refrigeration cycle using a first refrigerant that is a flammable refrigerant, a tank (41) that stores water heated directly or indirectly by the first refrigerant, and a casing (60) that houses the refrigerant unit (U) and the tank (41) and is arranged in an indoor space (I). The refrigerant circuit (R1) has a compressor (21), a first heat exchanger (23) that exchanges heat between the first refrigerant in the refrigerant circuit (R1) and the water in the water circuit (W), a decompression mechanism (24), and a second heat exchanger (22) that exchanges heat between the first refrigerant in the refrigerant circuit (R1) and the heat medium in the heat medium circuit (R2, 100). The refrigerant unit (U) is arranged above the tank (41).

[0007] In the first embodiment, the refrigerant unit (U) is positioned above the tank (41), thereby raising the position of the refrigerant unit (U). When refrigerant leaks from the refrigerant circuit (R1) of the refrigerant unit (U), the flammable refrigerant, which has a higher specific gravity than air, flows downward from the refrigerant unit (U). The refrigerant gradually diffuses into the air as it reaches the floor of the room (I). This reduces the concentration of the leaked refrigerant.

[0008] In a second embodiment, the casing (60) has a first side surface (63) having a first access port (A1) of a first space (S1) in which a refrigerant unit (U) is housed, and a second side surface (64) of the casing (60) located opposite to the first side surface (63). The hot water supply unit further comprises a support member (70) that supports the refrigerant unit (U) and is movable in and out of the first access port (A1).

[0009] In the second embodiment, the refrigerant unit (U) can be removed from the casing (60) by moving the support member (70) to the outside of the casing (60) through the first access port (A1). This allows the worker to perform the predetermined work with the refrigerant unit (U) in the outdoor space, thereby reducing the risk of leakage of the flammable first refrigerant.

[0010] In the third embodiment, the refrigerant unit (U) has a first heat exchanger (23) and a water circuit (W), and a water-side connection part (C1, C2) for detachably connecting the water circuit (W) and a second heat exchanger (22), and a heat medium-side connection part (C3, C4) for detachably connecting the heat medium circuit (R2, 100).

[0011] In the third embodiment, the first heat exchanger (23) can be disconnected from the water circuit (W) by releasing the connections at the water-side connections (C1, C2). The second heat exchanger (22) can be disconnected from the heat transfer medium circuit (R2, 100) by releasing the connections at the heat transfer medium-side connections (C3, C4). As a result, the refrigerant unit (U), which is disconnected from the water circuit (W) and the heat transfer medium circuit (R2, 100), can be easily removed from the casing (60) through the first access port (A1).

[0012] In the fourth aspect, as in the third aspect, the refrigerant unit (U) is closer to the first side surface (63) than to the water side connection parts (C1, C2) and the heat transfer medium side connection parts (C3, C4).

[0013] In the fourth embodiment, by bringing the refrigerant unit (U) closer to the first side surface (63), the refrigerant unit (U) is less likely to interfere with the water circuit (W) or the heat transfer fluid circuit (R2, 100). This makes it easier to insert and remove the refrigerant unit (U).

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

[0015] In the fifth embodiment, the worker can access the water-side connections (C1, C2) and the heat transfer medium-side connections (C3, C4) from the upper side of the casing (60) through the second access port (A2).

[0016] The sixth embodiment further comprises, in any one of the first to fifth embodiments, a first external connection portion (83, 84, 85, 86) provided on the upper surface (61) of the casing (60) to which water pipes (93, 94, 95, 96) of a water circuit (W) from outside the casing (60) are connected.

[0017] In the sixth embodiment, the refrigerant unit (U) is located above the tank (41). The first external connection points (83, 84, 85, 86) are located on the upper surface of the casing (60). As a result, the distance from the first heat exchanger (23) to the first external connection points (83, 84, 85, 86) is shortened.

[0018] A seventh aspect is the sixth aspect, wherein the casing (60) has a first side surface (63) having a first access port (A1) of a first space (S1) in which a refrigerant unit (U) is housed, and a second side surface (64) on the opposite side of the casing (60) from the first side surface (63). The first external connection portions (83, 84, 85, 86) are located closer to the second side surface (64) than to the first side surface (63).

[0019] The eighth embodiment further comprises, in any one of the first to seventh embodiments, a second external connection portion (81, 82) provided on the upper surface (61) of the casing (60) to which the refrigerant piping (91, 92) of the heat transfer medium circuit (R2, 100) from outside the casing (60) is connected.

[0020] In the eighth embodiment, the refrigerant unit (U) is located above the tank (41). The second external connection parts (81, 82) are located on the upper surface of the casing (60). As a result, the distance from the second heat exchanger (22) to the second external connection parts (81, 82) is shortened.

[0021] The ninth aspect is the eighth aspect, wherein the casing (60) has a first side surface (63) having a first access port (A1) of a first space (S1) in which a refrigerant unit (U) is housed, and a second side surface (64) located on the opposite side of the casing (60) from the first side surface (63). The second external connection portions (81, 82) are located closer to the second side surface (64) than to the first side surface (63).

[0022] In the tenth embodiment, in any one of the first to ninth embodiments, the casing (60) has a communication passage (78) that connects the interior space (I) with a first space (S1) in which a refrigerant unit (U) is housed.

[0023] In the tenth embodiment, when refrigerant leaks from the refrigerant circuit (R1) of the refrigerant unit (U), this refrigerant can be discharged from the first space (S1) through the communication passage (78) to the indoor space (I) outside the casing (60). As a result, diffusion of the refrigerant outside the casing (60) can be promoted, and the concentration of this refrigerant can be reduced.

[0024] In the eleventh embodiment, as in the tenth embodiment, the communication passage (78) is located lower than the refrigerant unit (U).

[0025] In the eleventh embodiment, by forming the communication passage (78) at a lower position than the refrigerant unit (U), refrigerant leaking from the refrigerant circuit (R1) is more easily guided into the communication passage (78). Therefore, diffusion of the refrigerant outside the casing (60) can be promoted.

[0026] A twelfth embodiment, in the tenth or eleventh embodiment, further comprises a refrigerant sensor (79) for detecting leakage of the first refrigerant. The refrigerant sensor (79) is located in or near the communication passage (78).

[0027] In the twelfth embodiment, the refrigerant sensor (79) is located in or near the communication passage (78), so that the refrigerant leak can be quickly detected by the refrigerant sensor (79).

[0028] A thirteenth embodiment further comprises, in the tenth or eleventh embodiment, an inner casing (70) disposed in a first space (S1) and housing a refrigerant unit (U). The inner casing (70) has an opening (70a) that connects the outside and the inside of the inner casing (70).

[0029] In the 13th embodiment, refrigerant leaking from the refrigerant circuit (R1) can be stored inside the inner casing (70). The refrigerant inside 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 to the outside of the casing (60) via the communication passage (78). In this way, the rate at which the refrigerant flows out to the outside of the casing (60) can be slowed, and the concentration of refrigerant outside the casing (60) can be reduced.

[0030] A fourteenth aspect is the hot water supply unit in the thirteenth aspect, further comprising a refrigerant sensor (79) for detecting leakage of the first refrigerant. The refrigerant sensor (79) is located inside the inner casing (70) or near the opening (70a).

[0031] In the 14th embodiment, the refrigerant sensor (79) is positioned in or near the opening (70a) of the inner casing (70), so that the refrigerant leak can be quickly detected by the refrigerant sensor (79).

[0032] The 15th embodiment further comprises a shielding member (98) that shields the heat transfer medium side connection portion (C3, C4) and the refrigerant circuit (R1) from each other, in any one of the third to fifth embodiments.

[0033] In the 15th embodiment, the refrigerant circuit (R1) filled with the first refrigerant, which is a flammable refrigerant, is shielded from the heat transfer medium side connection parts (C3, C4) by a shielding member (98). This reduces the risk of the first refrigerant igniting when the heat transfer medium side connection parts (C3, C4) are connected.

[0034] The sixteenth embodiment, in any one of the first to fifteenth embodiments, further comprises an electrical unit (71) housed within a casing (60). The electrical unit (71) is positioned above the tank (41).

[0035] In the sixteenth embodiment, if refrigerant leaks from the refrigerant circuit (R1) and accumulates at the bottom of the casing (60), the electrical component unit (71) becomes less susceptible to the effects of the refrigerant accumulated at the bottom.

[0036] A 17th embodiment further comprises an electrical component unit (71) housed within the casing (60) in any of the 10th to 14th embodiments. The electrical component unit (71) is positioned higher than the communication passage (78).

[0037] In the 17th embodiment, the electrical component unit (71) becomes less susceptible to the effects of leaked refrigerant.

[0038] The eighteenth embodiment is one of the first to seventeenth embodiments, in which the heat transfer medium circuit (R2, 100) is a second refrigerant circuit (R2) that performs a refrigeration cycle using a second refrigerant.

[0039] In the 18th embodiment, the hot water supply unit performs a so-called dual refrigeration cycle.

[0040] Figure 1 is a piping diagram of the hot water supply system of the embodiment. Figure 2 is a perspective view showing the external appearance of the hot water supply unit. Figure 3 is a schematic plan view showing the arrangement of equipment in the first space. Figure 4 is a top view of the top plate. Figure 5 is a longitudinal cross-sectional view showing the internal structure of the first space of the casing. Figure 6 is a longitudinal cross-sectional view showing the internal structure of the first space of the casing of the hot water supply unit of Modification 1. Figure 7 is a longitudinal cross-sectional view showing the internal structure of the first space of the casing of the hot water supply unit of Modification 2. Figure 8 is a schematic plan view showing the arrangement of equipment in the first space of the hot water supply unit of Modification 3. Figure 9 is a piping diagram of the hot water supply system of Modification 4.

[0041] Embodiments of this disclosure will be described in detail below with reference to the drawings. This disclosure is not limited to the embodiments shown below, and various modifications are possible without departing from the technical idea of ​​this disclosure. Since the drawings are for conceptual illustration of this disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.

[0042] (1) Configuration of the hot water supply system (1-1) Overall configuration The hot water supply system (1) supplies hot water to the target. The target of this embodiment includes hot water supply targets such as faucets, showers, and baths, as well as a heating device (5) that uses hot water. The hot water supply system (1) is connected to the hot water supply targets and the heating device (5) via water piping. The hot water supply system (1) has an outdoor unit (10) located outside the room and a hot water supply unit (20) located inside the room.

[0043] The hot water supply system (1) has a circuit configuration consisting of 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 the first refrigerant. The second refrigerant circuit (R2) is filled with carbon dioxide as the second refrigerant. The second refrigerant circuit (R2) is an example of a heat transfer medium circuit, and carbon dioxide is an example of a heat transfer medium.

[0044] The first refrigerant is propane (R290), a highly flammable natural refrigerant. Natural refrigerants have a zero ozone depletion potential, a low global warming potential, and impose little environmental burden. Propane ignites at temperatures below 500 °C. The flammable refrigerant may be methane (R50), ethane (R170), butane (R600), or isobutane (R600a). The flammable refrigerant may be a slightly flammable refrigerant rather than a highly flammable refrigerant. Examples of slightly flammable refrigerants include difluoromethane (R32) and tetrafluoropropene (HFO-1234yf). The first refrigerant may be a single refrigerant composed of one of the refrigerants described above, or a mixed refrigerant composed of one of the refrigerants described above and one or more other refrigerants.

[0045] The hot water supply system (1) includes 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). 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 a first heat exchanger, and the first water heat exchanger (23) is an example of a second heat exchanger. The hot water supply system (1) performs a so-called binary refrigeration cycle using the first refrigerant circuit (R1) and the second refrigerant circuit (R2).

[0046] (1-2) Outdoor unit The outdoor unit (10) includes a part of the second refrigerant circuit (R2). As components 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). The outdoor unit (10) has an outdoor fan (16). The second compressor (11) compresses the inhaled refrigerant and discharges the compressed refrigerant. The outdoor heat exchanger (12) exchanges heat between the outdoor air conveyed by the outdoor fan (16) and the second refrigerant. The second expansion valve (13) reduces the pressure of the refrigerant. The four-way switching valve (14) switches between a first state shown by the solid line in FIG. 1 and a second state shown by the dashed line in FIG. 1. The second accumulator (15) stores the liquid refrigerant before it is inhaled by the second compressor (11).

[0047] (1-3) Circuit Configuration of the Hot Water Supply Unit The hot water supply unit (30) includes the entire first refrigerant circuit (R1). The hot water supply unit (20) has, as component devices of the first refrigerant circuit (R1), a first compressor (21), a refrigerant heat exchanger (22), a first water heat exchanger (23), a first expansion valve (24), and a first accumulator (25). The first compressor (21) compresses the inhaled refrigerant and discharges the 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 pressure-reducing mechanism that reduces the pressure of the refrigerant. The first accumulator (25) stores the liquid refrigerant before it is inhaled by the first compressor (21). The refrigerant heat exchanger (22) and the first water heat exchanger (23) are constituted by, for example, plate heat exchangers.

[0048] The hot water supply unit (20) includes a part of the second refrigerant circuit (R2). The hot water supply unit (20) has, as component devices of the second refrigerant circuit (R2), in addition to the first water heat exchanger (23) described above, a second water heat exchanger (26). 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 constituted by, for example, plate heat exchangers.

[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 piping constituting the second refrigerant circuit (R2). One end of the first pipe (31) is connected to the 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 the liquid side line of the second medium circuit (R2). One end of the bypass pipe (34) is connected to the middle section of the first pipe (31). The other end of the bypass pipe (34) is connected to the middle section of the second pipe (32). The first pipe (31) is provided with a first on-off valve (35) between the connection point of 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) has a part of the water circuit (W). In addition to the first water heat exchanger (23) and the second water heat exchanger (26) described above, the hot water supply unit (20) has a pump (40), a tank (41), and an internal heat exchanger (42) as components of the water circuit (W).

[0051] The pump (40) circulates the water in the water circuit (W). Figure 1 shows the direction of water circulation in the water circuit (W) with arrows.

[0052] The tank (41) stores water (more precisely, hot water) to be supplied to the target. The tank (41) is a hollow container with a hot water storage space (41a) formed inside. A water supply pipe (43) and a hot water outlet pipe (44) are connected to the tank (41). One end of the water supply pipe (43) is connected to the bottom of the tank (41), and the other end of the water supply pipe (43) is connected to the water supply pipe. When the water level in the tank (41) decreases, the water supply pipe (43) supplies cold water from the water supply pipe into the tank (41). One end of the hot water outlet pipe (44) is connected to the top of the tank (41), and the other end of the hot water outlet pipe (44) is connected to a designated hot water supply target. The hot water outlet pipe (44) supplies the hot water from the tank (41) to the hot water supply target, such as a faucet, shower, or bath.

[0053] The internal heat exchanger (42) is located in the hot water storage space (41a). The internal heat exchanger (42) in this embodiment is a spirally formed heat transfer tube. Hot water heated by the first water heat exchanger (23) and the second water heat exchanger (26) flows inside the internal heat exchanger (42). The internal heat exchanger (42) exchanges heat between the hot water flowing inside it and the surrounding water. As a result, the water in the hot water storage space (41a) is heated by the internal heat exchanger (42). In this way, the tank (41) in this embodiment stores water that has been 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 heating side flow path (52). The outlet end of the main flow path (50) is connected to the inlet end of the hot water supply side flow path (51) and the inlet end of the heating side flow path (52). A three-way valve (53) is connected to the water circuit (W). The three-way valve (53) switches between a first state in which the main flow path (50) and the hot water supply side flow path (51) are connected, and a second state in which the main flow path (50) and the heating side flow path (52) are connected.

[0055] The main flow path (50) is connected in order to 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).

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

[0057] The heating-side flow path (52) is connected to the user-side heat exchanger (6) of the heating device (5). The user-side heat exchanger (6) heats the air in the target space (indoor space). The user-side heat exchanger (6) consists of a fin-and-tube type heat exchanger or a radiant panel. The user-side heat exchanger (6) consists of an air heat exchanger that directly heats the air in the target space, or a heat exchanger for floor heating that heats the 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 heating side flow path (52). The supply pipe (52a) is a flow path for supplying 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 for returning the water that has been heated in the utilization side heat exchanger (6) back to the main flow path (50).

[0059] The hot water supply unit (20) further includes a heater unit (54) and an expansion tank (55) as equipment elements of the water circuit (W). The heater unit (54) is installed in the main flow path (50) and provides auxiliary heating of the water in the water circuit (W). The expansion tank (55) communicates with the main flow path (50) and mitigates the rise in water pressure in the water circuit (W).

[0060] (2) Structure of the hot water supply unit The structure of the hot water supply unit (20) will be explained with reference to Figures 1 to 5. In the following explanation, terms such as up, down, front, back, right, and left will be based on the directions indicated by the arrows in Figure 2.

[0061] (2-1) Casing As shown in Figure 2, the hot water supply system (1) has a casing (60) that is placed in the interior space (I). The interior space (I) is a space formed inside the building and includes not only living spaces but also non-living spaces such as corridors, basements, warehouses, and garages. The casing (60) is installed on the floor surface of the interior space (I). The casing (60) is formed in the shape of a hollow box. The casing (60) has a rectangular parallelepiped shape. The vertical height of the casing (60) is greater than the front-to-back length and left-to-right width of the casing (60). The casing (60) has an upper plate (61), a bottom plate (62), a front plate (63), a rear plate (64), a right plate (65), and a left plate (66). The upper plate (61) constitutes the upper surface of the casing (60), and the bottom plate (62) constitutes the lower surface of the casing (60). The front panel (63) constitutes the front surface, which is the first side surface of the casing (60), and the rear panel (64) constitutes the rear surface, which is the second side surface of the casing (60). The right panel (65) constitutes the right surface, which is the third side surface of the casing (60), and the left panel (66) constitutes the left surface, which is the fourth side surface of the casing (60).

[0062] A partition plate (67) is provided inside the casing (60). The partition plate (67) divides the inside of the casing (60) vertically. Specifically, the partition plate (67) divides the inside of the casing (60) into a first space (S1) and a second space (S2). The first space (S1) is formed in the upper part of the casing (60). The second space (S2) is formed from the middle to the lower part of the casing (60). The first space (S1) and the second space (S2) are formed in the shape of a rectangular parallelepiped. The height of the second space (S2) is greater than the height of the first space (S1). A tank (41) is placed in the second space (S2). In other words, the tank (41) is installed on the bottom plate (62) of the casing (60).

[0063] In the installed state of the casing (60), a workspace (S3) is secured in front of the casing (60). A first access opening (A1) is formed on the upper part of the front plate (63) of the casing (60). A first opening / closing cover (68), which is part of the front plate (63), is detachably attached to the first access opening (A1). An operator can access the first space (S1) inside the casing (60) from the workspace (S3) through the first access opening (A1).

[0064] As shown in Figure 4, a second access opening (A2) is formed in the top plate (61). A second opening / closing cover (69), which is part of the top plate (61), is detachably attached to the second access opening (A2). The worker can access the first space (S1) inside the casing (60) from the work space (S3) through the second access opening (A2). The structure of the second opening / closing cover (69) will be described in detail later.

[0065] (2-2) Layout diagram 3 of the equipment in the first space shows the arrangement of each piece of equipment, including the refrigerant unit (U) and the electrical equipment unit (71). Diagram 3 schematically shows the piping connecting each piece of equipment and the connections between these pipes. Therefore, the position and shape of these pipes and connections are not limited to those shown in Diagram 3.

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

[0067] The refrigerant unit (U) is positioned closer to the front plate (63) than to the rear plate (64). The refrigerant unit (U) is positioned closer to the left plate (66) than to the right plate (65). The first compressor (21) is positioned near the first access port (A1). The first compressor (21) is visible from outside the casing (60) through the first access port (A1) when the first opening / closing cover (68) is removed. The refrigerant unit (U) is positioned 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 located behind the first compressor (21). In this embodiment, the refrigerant heat exchanger (22) is located to the right of the first water heat exchanger (23). The first expansion valve (24) is located 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 member (70) that supports the refrigerant unit (U). The support member (70) is located below the refrigerant unit (U) and supports the support member (70) from below. The support member (70) is configured to be retractable from the first access opening (A1) along the bottom plate (62). It is preferable that the bottom plate (62) be provided with a guide member that guides the support member (70) in the front-rear direction. The structure of the support member (70) will be described in detail later.

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

[0071] The electrical components unit (71) includes a control board for controlling each component of the hot water supply unit (20). The electrical components unit (71) is located near the first access port (A1). The electrical components unit (71) is visible from outside the casing (60) through the first access port (A1) when the first opening / closing cover (68) is removed.

[0072] The second water heat exchanger (26) is located behind the electrical equipment unit (71). A first shut-off valve (35) and a second shut-off valve (36) are located between the second water heat exchanger (26) and the electrical equipment unit (71). A first pipe (31) and a third pipe (33), which are refrigerant pipes, are located around the second water heat exchanger (26). The first pipe (31) and the third pipe (33) extend vertically through the first space (S1).

[0073] In the first space (S1), a connection space (75) is formed behind the electrical component unit (71). The connection space (75) is formed towards the front of the first space (S1). A first connection part (C1), a second connection part (C2), a third connection part (C3), and a fourth connection part (C4) are arranged in the connection space (75).

[0074] The first connection (C1) and the second connection (C2) constitute a water-side connection that detachably connects the first water heat exchanger (23) and the water circuit (W). As shown in Figure 1, the first connection (C1) connects the water piping on the outlet side of the fourth flow path (P4) of the first water heat exchanger (23) to the water circuit (W). The second connection (C2) connects the water piping on the inlet side of the fourth flow path (P4) of the first water heat exchanger (23) to the water circuit (W). The third connection (C3) and the fourth connection (C4) constitute a heat transfer medium-side connection that detachably connects the refrigerant heat exchanger (22) and the second refrigerant circuit (R2). The third connection (C3) connects the refrigerant piping on the gas side of the second flow path (P2) of the refrigerant heat exchanger (22) to the second refrigerant circuit (R2). The fourth connection (C4) connects the liquid-side refrigerant piping of the second flow path (P2) of the refrigerant heat exchanger (22) to the second refrigerant circuit (R2). The first connection (C1) and the second connection (C2) may directly connect the first water heat exchanger (23) to the water circuit (W), or they may be connected indirectly via piping. The third connection (C3) and the fourth connection (C4) may directly connect the refrigerant heat exchanger (22) to the second refrigerant circuit (R2), or they may be connected indirectly via piping.

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

[0076] In the first space (S1), a water circuit side space (76) is formed, where the components of the water circuit (W) are arranged towards the rear. A pump (40), a heater unit (54), a three-way valve (53), and an expansion tank (55) are arranged in the water circuit side space (76). An inlet pipe (51a), an outlet pipe (51b), a supply pipe (52a), and a return pipe (52b) are arranged in the water circuit side space (76) as water piping.

[0077] The supply pipe (52a) and return pipe (52b) pass through the top plate (61) and connect to the water piping outside the casing (60). The inlet pipe (51a) and outlet pipe (51b) pass through the partition plate (67) and connect to the internal heat exchanger (42).

[0078] The first space (S1) contains the first pipe (31), the second pipe (32), and the third pipe (33). The other end of the first pipe (31) extends rearward along the right plate (65). The second pipe (32) is located in the middle of the first space (S1) in the front-to-back direction and extends left and right from the refrigerant heat exchanger (22) to the second heat exchanger (22). The other end of the third pipe (33) extends rearward along the right plate (65).

[0079] Although not shown in the diagram, other equipment for the water circuit (W) is arranged in the first space (S1). The other equipment includes drain valves, ball valves, flow sensors, and filters. It is preferable that the other equipment be positioned closer to the front plate (63) than to the rear plate (64).

[0080] (2-3) Connection part of the upper plate and its surrounding structure As shown in Figures 2 and 4, the upper 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 connect the piping inside the casing (60) to the piping outside the casing (60).

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

[0082] After the worker installs the casing (60) in the indoor space (I), the worker connects the external piping of the casing (60) to each fitting. Specifically, the first liquid-side connecting pipe (91) that connects to the outdoor unit (10) is connected to the upper end of the first refrigerant fitting (81). The second gas-side connecting pipe (92) that connects to the outdoor unit (10) is connected to the upper end of the second refrigerant fitting (82). The third water pipe (95) on the inlet side of the heating device (5) is connected to the upper end of the first water fitting (83). The fourth water pipe (96) on the outlet side of the heating device (5) is connected to the upper end of the second water fitting (84). The first water pipe (93) for water supply is connected to the upper end of the third water fitting (85). The second water pipe (94) for hot water supply is connected to the upper end of the fourth water fitting (86).

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

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

[0085] The second opening / closing cover (69) opens and closes the second access port (A2). A rear frame (F) extending to the left and right is formed behind the second opening / closing cover (69). The first outer connection parts (83, 84, 85, 86) and the second outer connection parts (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) have holes formed at positions corresponding to each joint (81, 82, 83, 84, 85, 86). In this embodiment, arc-shaped grooves are formed on the front edge of the rear frame (F) and the rear edge of the second opening / closing cover (69), and these grooves constitute holes through which each joint (81, 82, 83, 84, 85, 86) or each pipe passes. Grooves for forming holes may be formed on only one of the rear frame (F) or the second opening / closing cover (69).

[0086] (2-4) Configuration diagram 5 regarding measures to prevent refrigerant leakage shows that the support member (70) of this embodiment constitutes an inner casing for housing the refrigerant unit (U). The support member (70) is formed in the shape of a rectangular box. Components of the refrigerant unit (U), such as a compressor (21), are installed on the bottom surface of the support member (70). An opening (70a) is formed in the side wall of the support member (70). The opening (70a) connects the inside of the support member (70) to the outside of the support member (70). The opening (70a) is formed in the left side wall of the support member (70), but may also be formed in the front, rear, or right side wall. The opening (70a) is formed in the lower part of the support member (70), more precisely along the bottom of the support member (70). The opening (70a) is composed of an elongated hole extending in the front-rear direction. The opening (70a) may also be a circular hole.

[0087] The partition plate (67) of this embodiment has a partition plate body (67a) on which a refrigerant unit (U) is installed, and a stepped portion (67b) recessed downward from the outer edge of the partition plate body (67a). The partition plate (67) of this embodiment has stepped portions (67b) on both the left and right sides of the partition plate body (67a). The stepped portion (67b) defines a relay groove (77) inside it. The relay groove (77) is formed in a rectangular shape when viewed in a cross section perpendicular to the front-rear direction. The relay groove (77) extends in the front-rear direction along the opening (70a). The relay groove (77) constitutes a part of the first space (S1).

[0088] The casing (60) has a passage (78) that connects the first space (S1) to the interior space (I) outside the casing (60). The passage (78) opens toward the interior space (I). In this embodiment, the passage (78) is formed in both the left plate (66) and the right plate (65). The passage (78) is formed at the same height as the intermediate groove (77) and is directly connected to the intermediate groove (77). The refrigerant unit (U) and the electrical component unit (71) are located at a higher position than the passage (78).

[0089] The hot water supply unit (20) has a refrigerant sensor (79) for detecting refrigerant leakage. In this embodiment, the refrigerant sensor (79) is positioned near the opening (70a). More precisely, the refrigerant sensor (79) is positioned within a range of 10 cm from the opening (70a).

[0090] (2-5) Controller and Alarm Device As schematically shown in Figure 1, the hot water supply unit (20) includes a controller (120) and an alarm 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 alarm device (121) is an example of a device for preventing refrigerant leaks. The alarm device (121) notifies the user of initial information regarding refrigerant leaks by sound and light. When the concentration of refrigerant detected by the refrigerant sensor (79) exceeds a predetermined value, the controller (120) triggers the alarm device (121) to emit the initial information.

[0092] (3) Operation of the hot water supply system (1) During operation, the second refrigerant circuit (R2) performs a subcritical or supercritical cycle while the first refrigerant circuit (R1) performs a subcritical cycle. The second refrigerant circuit (R2) switches between the first and second operations. The water circuit (W) switches between the third and fourth operations.

[0093] In the first operation, the four-way switching valve (14) enters the first state, the first on-off valve (35) enters the open state, and the second on-off valve (36) enters 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), is depressurized by the second expansion valve (13), and evaporates in the outdoor heat exchanger (12).

[0094] In the second operation, the four-way switching valve (14) enters the first state, the first on-off valve (35) enters the closed state, and the second on-off valve (36) enters the open state. In the first operation, the refrigerant compressed by the second compressor (11) bypasses the second water heat exchanger (26), dissipates heat in the refrigerant heat exchanger (22), is depressurized by the second expansion valve (13), and 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), is depressurized in the first expansion valve (24), and evaporates in the refrigerant heat exchanger (22).

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

[0097] In the fourth operation, the three-way valve (53) enters the second state. In the fourth operation, the water transported by the pump (40) is heated either in the first water heat exchanger (23) only, or in both the second water heat exchanger (26) and the first water heat exchanger (23). After heating, the water releases heat into the air of the target space in the user-side heat exchanger (6) of the heating device (5), resulting in the target space being heated.

[0098] (4) Work of the worker When shipping and transporting the hot water supply unit (20), the worker moves the refrigerant unit (U) and the casing (60) separately. If the hot water supply unit (20) is transported with the refrigerant unit (U) placed in the first space (S1) inside the casing (60), the center of gravity of the hot water supply unit (20) will be raised, making transport and installation work difficult. The worker can transport the refrigerant unit (U), which is separate from the casing (60), together with the support member (70).

[0099] Next, the worker places the refrigerant unit (U) and support member (70) into the casing (60). Specifically, the worker places the support member (70) that supports the refrigerant unit (U) into the first space (S1) from the work space (S3) side through the first access port (A1).

[0100] The worker connects the first connection point (C1), second connection point (C2), third connection point (C3), and fourth connection point (C4) through the first access port (A1). This connects the refrigerant unit (U) to the water circuit (W) and the second refrigerant circuit (R2). Note that the refrigerant in the first refrigerant circuit (R1) may be filled before transport or during installation.

[0101] The worker connects the piping to each fitting on the top plate (61). Specifically, the worker connects the first connecting pipe (91) to the first refrigerant fitting (81) and the second connecting pipe (92) to the second refrigerant fitting (82). The worker also connects the water pipes (93, 94, 95, 96) corresponding to each water fitting (83, 84, 85, 86).

[0102] With each pipe connected to each fitting (81, 82, 83, 84, 85, 86), the worker can remove the second opening / closing cover (69) of the top plate (61). This is because, as shown in Figure 4, each pipe (91, 92, 93, 94, 95, 96) is located in the groove between the second opening / closing cover (69) and the rear frame (F). Therefore, the worker can connect or disconnect the first connection (C1), second connection (C2), third connection (C3), and fourth connection (C4) through the second access port (A2).

[0103] The worker can remove the refrigerant unit (U) from the casing (60) and perform maintenance on the refrigerant unit (U). Specifically, the worker in the workspace (S3) removes the first opening / closing cover (68) from the casing (60) to expose the first access port (A1). The worker then disconnects the first connection port (C1), the second connection port (C2), the third connection port (C3), and the fourth connection port (C4) through the first access port (A1). As a result, the refrigerant unit (U) is disconnected from the water circuit (W) and the second refrigerant circuit (R2). Even in this state, the first refrigerant circuit (R1) of the refrigerant unit (U) remains a closed circuit, so the risk of flammable refrigerant leaking from the first refrigerant circuit (R1) is smaller than when the disconnection is performed within the first refrigerant circuit (R1). Since the refrigerant in the second refrigerant circuit (R2) is carbon dioxide, even if refrigerant leaks from the second refrigerant circuit (R2), it will not cause any major problems.

[0104] The worker moves the support member (70) forward through the first access opening (A1). This allows the refrigerant unit (U) to be removed from the casing (60) along with the support member (70) through the first access opening (A1). The refrigerant unit (U) is located closer to the front plate (63) than the first connection part (C1), the second connection part (C2), the third connection part (C3), and the fourth connection part (C4). Therefore, interference between the refrigerant unit (U) and these connection parts can be suppressed, and the refrigerant unit (U) can be easily removed.

[0105] The worker performs maintenance on the removed refrigerant unit (U) in the outdoor space rather than the indoor space (I). This mitigates problems caused by leakage, even if flammable refrigerant leaks from the first refrigerant circuit (R1). After completing maintenance on the refrigerant unit (U), the worker returns the refrigerant unit (U) to its original position along with the support member (70). The worker then reconnects the first connection (C1), second connection (C2), third connection (C3), and fourth connection (C4).

[0106] (5) Operation when refrigerant leaks The operation when refrigerant leaks will be explained. Figure 5 shows the leaked refrigerant with a dashed arrow. When refrigerant leaks from the first refrigerant circuit (R1), this refrigerant accumulates inside the support member (70). The refrigerant inside the support member (70) flows out into the first space (S1) (more precisely, the space between the casing (60) and the support member (70)). The refrigerant in the first space (S1) flows down into the intermediate groove (77) inside the stepped portion (67b). The refrigerant in the intermediate groove (77) flows out to the outside of the casing (60) through the connecting passage (78) of the casing (60).

[0107] Since the refrigerant unit (U) is located above the tank (41), the refrigerant flowing out from the first refrigerant circuit (R1) is also at a high position. As a result, the distance the refrigerant travels to reach the bottom plate (62) of the casing (60) is increased. Consequently, the refrigerant flowing out through the communication passage (78) diffuses before reaching the floor of the room space (I). As a result, the concentration of the refrigerant can be reduced. In particular, as the refrigerant falls downward, it diffuses horizontally, thus reducing the concentration of the refrigerant near the floor. Therefore, it is possible to prevent the refrigerant concentration from reaching the LFL (Lower Flammable Limit).

[0108] Since the connecting passage (78) is located lower than the refrigerant unit (U), the flammable refrigerant, which has a higher specific gravity than air, can be reliably guided into the connecting passage (78).

[0109] The inner casing, which is the support member (70), houses the refrigerant unit (U). This delays the time it takes for the refrigerant to flow out of the casing (60) through the communication passage (78). Consequently, the amount of refrigerant flowing out from the communication passage (78) can be limited, and the concentration of refrigerant in the indoor space (I) can be reduced.

[0110] The refrigerant sensor (79) is positioned near the opening (70a). Therefore, the refrigerant sensor (79) can quickly detect refrigerant leakage. In particular, since the refrigerant sensor (79) is located in the flow path between the opening (70a) and the communication passage (78), the refrigerant sensor (79) can quickly detect refrigerant leakage. When the refrigerant sensor (79) detects refrigerant leakage, the controller (120) causes the alarm device (121) to emit first information. Therefore, the user can quickly take countermeasures against refrigerant leakage.

[0111] (6) Effects of the Embodiment (6-1) The refrigerant unit (U) is positioned above the tank (41). In this configuration, the position of the refrigerant unit (U) is elevated. As a result, the refrigerant leaking from the refrigerant unit (U) gradually diffuses into the air before reaching the floor of the indoor space (I). This reduces the concentration of the leaked refrigerant.

[0112] (6-2) The casing (60) has a first side surface (63) having a first access port (A1) of a first space (S1) in which a refrigerant unit (U) is housed, and a second side surface (64) located on the opposite side of the casing (60) from the first side surface (63). The hot water supply unit further includes a support member (70) that supports the refrigerant unit (U) and is removable from the first access port (A1).

[0113] In this configuration, the refrigerant unit (U) can be removed from the casing (60) by moving the support member (70) to the outside of the casing (60) through the first access port (A1). This allows the worker to perform the required work with the refrigerant unit (U) in the outdoor space, thereby reducing the risk of leakage of the flammable first refrigerant.

[0114] In addition, the worker can move the refrigerant unit (U) and the casing (60) separately, with the refrigerant unit (U) removed from the casing (60). If the hot water supply unit (20) is transported with the refrigerant unit (U) installed inside the casing (60), the center of gravity of the hot water supply unit (20) will be higher. This is because the refrigerant unit (U) is located above the tank (41), and no water is stored in the tank (41) during transport. In contrast, by transporting the refrigerant unit (U) separately from the casing (60), the center of gravity of the casing (60) during transport is lowered. Therefore, the hot water supply unit (20) can be easily transported.

[0115] (6-3) The refrigerant unit (U) has a refrigerant heat exchanger (22) and water-side connection parts (C1, C2) that detachably connect to a water circuit (W), and a first water heat exchanger (23) and heat transfer medium-side connection parts (C3, C4) that detachably connect to a second refrigerant circuit (R2).

[0116] In this configuration, the first water heat exchanger (23) can be disconnected from the water circuit (W) by disconnecting the water-side connections (C1, C2). The refrigerant heat exchanger (22) can be disconnected from the second refrigerant circuit (R2) by disconnecting the heat transfer medium-side connections (C3, C4). As a result, the refrigerant unit (U), which is disconnected from the water circuit (W) and the second refrigerant circuit (R2), can be taken out of the casing (60) through the first access port (A1).

[0117] (6-4) The refrigerant unit (U) is closer to the first side surface (63) than to the water side connection parts (C1, C2) and the heat transfer medium side connection parts (C3, C4). In particular, the refrigerant unit (U) does not overlap with the water side connection parts (C1, C2) or the heat transfer medium side connection parts (C3, C4) in the front-to-back direction. This configuration makes it easier to insert and remove the refrigerant unit (U).

[0118] (6-5) The casing (60) has an upper plate (61) having a second access port (A2) of the first space (S1). In this configuration, the worker can access the water-side connection parts (C1, C2) and the heat transfer medium-side connection parts (C3, C4) from the upper side of the casing (60) through the second access port (A2).

[0119] (6-6) The casing (60) is further provided with a first external connection part (83, 84, 85, 86) provided on the upper plate (61) of the casing (60) to which water pipes (93, 94, 95, 96) of the water circuit (W) from outside the casing (60) are connected, and a second external connection part (81, 82) provided on the upper surface (61) of the casing (60) to which refrigerant pipes (91, 92) of the second refrigerant circuit (R2) from outside the casing (60) are connected.

[0120] In this configuration, the distance from the first water heat exchanger (23) to the first external connection points (83, 84, 85, 86) and the distance from the refrigerant heat exchanger (22) to the second external connection points (81, 82) are shortened. Therefore, the length of the piping between the first water heat exchanger (23) and the first external connection points (83, 84, 85, 86) and the length of the piping between the refrigerant heat exchanger (22) and the second external connection points (81, 82) can be shortened.

[0121] (6-7) The casing (60) has a connecting passage (78) that connects the indoor space (I) with the first space (S1) in which the refrigerant unit (U) is housed. In this configuration, when refrigerant leaks from the first refrigerant circuit (R1) of the refrigerant unit (U), this refrigerant can be discharged from the first space (S1) through the connecting passage (78) to the indoor space (I) outside the casing (60). As a result, diffusion of the refrigerant can be promoted before it falls to the floor, and the concentration of the refrigerant can be reduced.

[0122] The communication passage (78) is located lower than the refrigerant unit (U). In this configuration, by forming the communication passage (78) lower than the refrigerant unit (U), refrigerant leaking from the refrigerant circuit (R1) is more easily guided into the communication passage (78). Therefore, diffusion of refrigerant outside the casing (60) can be promoted. The refrigerant unit (U) and the electrical component unit (71) are located higher than the communication passage (78). As a result, the refrigerant unit (U) and the electrical component unit (71) are less affected by leaked refrigerant.

[0123] The hot water supply unit (20) is located in the first space (S1) and further comprises an inner casing (70) that houses a refrigerant unit (U). The inner casing (70) has an opening (70a) that connects the outside and inside of the inner casing (70). In this configuration, the rate at which the refrigerant flows out of the casing (60) can be slowed, thereby reducing the concentration of refrigerant outside the casing (60).

[0124] The refrigerant sensor (79) is positioned inside the inner casing (70) or near the opening (70a). In this configuration, the refrigerant sensor (79) can quickly detect refrigerant leakage.

[0125] (7) Modified Examples The above-described embodiment may also have the following modified configuration. The differences from the embodiment will be explained below.

[0126] (7-1) Modification 1 In Modification 1 shown in Figure 6, the refrigerant sensor (79) is placed inside the support member (70), which is the inner casing. Since the support member (70) houses the refrigerant unit (U), the concentration of refrigerant that leaks inside it increases rapidly. By placing the refrigerant sensor (79) inside the support member (70), refrigerant leakage can be detected quickly.

[0127] In particular, in Modification 1, by placing a refrigerant sensor (79) near the opening (70a) through which the refrigerant flows, refrigerant leakage can be detected quickly. The refrigerant sensor (79) may also be placed at the opening (70a).

[0128] (7-2) Modification 2 In Modification 2 shown in Figure 7, the refrigerant sensor (79) is positioned near the communication passage (78). The distance between the refrigerant sensor (79) and the communication passage (78) is 10 cm or less. In this example, the refrigerant sensor (79) is located outside the casing (60). However, the refrigerant sensor (79) may be positioned inside the casing (60) or in the communication passage (78). The refrigerant sensor (79) may also be positioned in the relay groove (77). In these configurations, the refrigerant flows easily around the refrigerant sensor (79), so refrigerant leakage can be detected quickly.

[0129] In the modified example 2, a guide plate (66a) is formed on the side plates (65, 66) of the casing (60). The guide plate (66a) is formed above the communication passage (78). The guide plate (66a) extends diagonally downward from the side plates (65, 66). The guide plate (66a) is formed, for example, by cutting and bending upward between a pair of vertically extending slits formed in the side plate. The refrigerant sensor (79) is positioned so as to overlap the guide plate (66a) vertically and also overlap the communication passage (78) laterally.

[0130] Modification 2 shown in Figure 7 does not have an inner casing. More precisely, the support member (70) is formed in a plate shape that is installed on the partition plate (67) so as to follow the partition plate (67). The refrigerant unit (U) is installed on the support member (70). In this configuration, refrigerant leaking from the refrigerant unit (U) can be quickly discharged to the outside of the casing (60), so the concentration of refrigerant inside the casing (60) can be quickly reduced.

[0131] (7-3) Modification 3 As shown in Figure 8, the hot water supply unit (20) of Modification 3 has a shielding member (98). The shielding member (98) is positioned towards the front in the first space (S1). The shielding member (98) is positioned between the refrigerant unit (U) and the connection space (75). The shielding member (98) shields the third connection part (C3) and the fourth connection part (C4) from the first refrigerant circuit (R1). The shielding member (98) is formed in a plate shape with the left-right direction as the plate thickness direction. In a top view, the shielding member (98) extends from near the front end of the casing (60) to an intermediate position in the front-rear direction of the casing (60). The upper end of the shielding member (98) is higher than the upper end of the first compressor (21). In this example, the shielding member (98) is formed integrally with the support member (70). The lower part of the shielding member (98) is continuous with the support member (70). The shielding member (98) may be constructed separately from the support member (70).

[0132] At the third connection point (C3) and the fourth connection point (C4), there is a possibility of brazing or welding when connecting pipes, or cutting when separating pipes. Such operations may cause sparks to fly to the first refrigerant circuit (R1). The shielding member (98) shields the third connection point (C3) and the fourth connection point (C4) from the first refrigerant circuit (R1), thereby suppressing sparks from flying to the first refrigerant circuit (R1). As a result, the risk of ignition of flammable refrigerant can be reduced.

[0133] (7-4) Modification 4 As shown in Figure 9, the hot water supply system (1) of Modification 4 has a primary side circulation circuit (100) as a heat transfer medium circuit instead of the second refrigerant circuit (R2) of the embodiment. The primary side circulation circuit (100) is filled with a heat transfer medium such as water or antifreeze. The configuration on the hot water supply unit (20) side of the primary side circulation circuit (100) is the same as in the embodiment. The primary side circulation circuit (100) has a circulation pump (101) and a ground heat exchanger (102) as elemental equipment installed outdoors. The circulation pump (101) circulates the heat transfer medium in the primary side circulation circuit (100). The ground heat exchanger (102) is a heat transfer tube that transfers heat from the ground to the heat transfer medium, and is formed, for example, in a spiral shape. The heat transfer medium heated in the ground heat exchanger (102) is released by the refrigerant heat exchanger (22) and used to generate hot water in the tank (41).

[0134] (8) Other embodiments The hot water supply system (1) may be a system that supplies hot water only to the heating device (5) from the tank (41).

[0135] The hot water supply unit (20) does not need to have a second water heat exchanger (26). In this case, the second refrigerant circuit (R2) will have a configuration in which the second water heat exchanger (26), bypass pipe (34), first shut-off valve (35), and second shut-off valve (36) are omitted.

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

[0137] The support member (70) may be box-shaped and house the refrigerant unit (U). In this case, the side plate of the support member (70) may constitute the shielding member (98) of Modification 1.

[0138] The refrigerant unit (U) and electrical components unit (71) do not necessarily have to overlap the tank (41) vertically. The refrigerant unit (U) and electrical components unit (71) only need to be positioned higher than the top edge of the tank (41).

[0139] The heat transfer fluid side connection points (C3, C4) and the water side connection points (C1, C2) may be provided on the side of the casing (60).

[0140] The expansion mechanism does not have to be an expansion valve; it may be a capillary tube or an inflator.

[0141] The connecting passage (78) may be a gap formed between the frame or plates of the casing (60). The connecting passage (78) may be located higher than the refrigerant unit (U). The hot water supply unit (20) may have an inner casing that houses the refrigerant unit (U), separate from the support member (70).

[0142] The countermeasures activated when a refrigerant leak is detected may include a shut-off valve that opens and closes the refrigerant circuit (R1), a fan that agitates the air, or a ventilation device corresponding to the indoor space (I).

[0143] (9) Other Descriptions Although embodiments and modifications have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate, as long as they do not impair the functions covered by this disclosure.

[0144] The designations "first," "second," "third," etc., mentioned above are used to distinguish between the terms to which these designations are attached, and do not limit the number or order of those terms.

[0145] As described above, this disclosure is useful for hot water supply units.

[0146] 20 Hot water supply unit 21 First compressor (compressor) 22 Refrigerant heat exchanger (second heat exchanger) 23 First water heat exchanger (first heat exchanger) 24 First expansion valve (pressure reducing mechanism) 41 Tank 60 Casing 61 Top plate (top surface) 63 Front plate (first side) 64 Rear plate (second side) 70 Support member (inner casing) 70a Opening 71 Electrical equipment unit 78 Connecting passage 79 Refrigerant sensor 81,82 Second outer connection part 83,84,85,86 First outer connection part 91,92 Refrigerant piping 93,94,95,96 Water piping 98 Shielding member A1 First access port A2 Second access port C1,C2 Water side connection part C3,C4 Heat transfer medium side connection part I Interior space R1 First refrigerant circuit (refrigerant circuit) R2 Second refrigerant circuit R2,100 Heat transfer medium circuit S1 First space U Refrigerant unit W Water circuit

Claims

1. A hot water supply unit comprising: a refrigerant unit (U) having a refrigerant circuit (R1) that performs a refrigeration cycle using a first refrigerant which is a flammable refrigerant; a tank (41) for storing water heated directly or indirectly by the first refrigerant; and a casing (60) that houses the refrigerant unit (U) and the tank (41) and is arranged in an indoor space (I), wherein the refrigerant circuit (R1) comprises: a compressor (21); a first heat exchanger (23) that exchanges heat between the first refrigerant of the refrigerant circuit (R1) and water in a water circuit (W); a pressure reducing mechanism (24); and a second heat exchanger (22) that exchanges heat between the first refrigerant of the refrigerant circuit (R1) and the heat transfer medium of a heat transfer medium circuit (R2,100), and the refrigerant unit (U) is arranged above the tank (41).

2. The hot water supply unit according to claim 1, wherein the casing (60) has a first side surface (63) having a first access port (A1) of a first space (S1) in which the refrigerant unit (U) is housed, and a second side surface (64) located on the opposite side of the casing (60) from the first side surface (63), and further comprises a support member (70) that supports the refrigerant unit (U) and can be moved in and out of the first access port (A1).

3. The hot water supply unit according to claim 2, wherein the refrigerant unit (U) comprises a water-side connection portion (C1, C2) that detachably connects the first heat exchanger (23) and the water circuit (W), and a heat medium-side connection portion (C3, C4) that detachably connects the second heat exchanger (22) and the heat medium circuit (R2, 100).

4. The hot water supply unit according to claim 3, wherein the refrigerant unit (U) is closer to the first side surface (63) than the water side connection portion (C1, C2) and the heat transfer medium side connection portion (C3, C4).

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

6. The hot water supply unit according to any one of claims 1 to 5, further comprising a first external connection part (83, 84, 85, 86) provided on the upper surface (61) of the casing (60), to which water pipes (93, 94, 95, 96) of the water circuit (W) from outside the casing (60) are connected.

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

8. The hot water supply unit according to any one of claims 1 to 7, further comprising a second external connection portion (81, 82) provided on the upper surface (61) of the casing (60), to which the refrigerant piping (91, 92) of the heat transfer medium circuit (R2, 100) from outside the casing (60) is connected.

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

10. The hot water supply unit according to any one of claims 1 to 9, wherein the casing (60) has a passage (78) that connects the indoor space (I) and the first space (S1) in which the refrigerant unit (U) is housed.

11. The hot water supply unit according to claim 10, wherein the connecting passage (78) is located at a lower position than the refrigerant unit (U).

12. The hot water supply unit according to claim 10 or 11, further comprising a refrigerant sensor (79) for detecting leakage of the first refrigerant, wherein the refrigerant sensor (79) is located in or near the communication passage (78).

13. A hot water supply unit according to claim 10 or 11, comprising an inner casing (70) disposed in the first space (S1) and housing the refrigerant unit (U), and the inner casing (70) having an opening (70a) that connects the outside and the inside of the inner casing (70).

14. The hot water supply unit according to claim 13, further comprising a refrigerant sensor (79) for detecting leakage of the first refrigerant, wherein the refrigerant sensor (79) is located inside the inner casing (70) or near the opening (70a).

15. The hot water supply unit according to any one of claims 3 to 5, further comprising a shielding member (98) that shields the heat transfer medium side connection portion (C3, C4) and the refrigerant circuit (R1) from each other.

16. The hot water supply unit according to any one of claims 1 to 15, further comprising an electrical component unit (71) housed within the casing (60), wherein the electrical component unit (71) is positioned above the tank (41).

17. The hot water supply unit according to any one of claims 10 to 14, further comprising an electrical component unit (71) housed within the casing (60), wherein the electrical component unit (71) is positioned higher than the communication passage (78).

18. The hot water supply unit according to any one of claims 1 to 17, wherein the heat transfer medium circuit (R2, 100) is a second refrigerant circuit (R2) that performs a refrigeration cycle using a second refrigerant.

Images