Hot water supply unit

Abstract

A 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 flammable; a tank (41) that stores water which is directly or indirectly heated by the first refrigerant; and a casing (60) that accommodates the refrigerant unit (U) and the tank (41) and is disposed in an indoor space (I). The refrigerant unit (U) is disposed below the 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 includes 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 provided with 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. The hot water supply unit is used for, for example, hot water supply and air conditioning applications. However, in such a configuration where the refrigerant unit is housed in the casing, problems occur in that conveyance work and installation work become difficult.

[0005] Specifically, when transporting the hot water supply unit to the indoor space or installing it in the indoor space, the tank can be emptied. In contrast, the refrigerant unit includes heavy objects such as a compressor, a first heat exchanger, and a second heat exchanger. Therefore, since the refrigerant unit is relatively heavier than the tank, there is a possibility that the center of gravity of the entire hot water supply unit will be offset. Conventionally, no consideration has been given to the center of gravity of the hot water supply unit during transportation or installation of the casing.

[0006] An object of the present disclosure is to suppress the difficulty of conveyance work and installation work of the hot water supply unit due to the offset of the center of gravity of the hot water supply unit.

[0007] The first embodiment relates to a hot water supply unit. The 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, 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) includes a compressor (21), a first heat exchanger (23) that exchanges heat between the first refrigerant of the refrigerant circuit (R1) and water in the 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 the heat transfer medium circuit (R2, 100). The refrigerant unit (U) is located below the tank (41).

[0008] In the first embodiment, the center of gravity of the hot water supply unit (20) can be lowered by positioning the refrigerant unit (U) below the tank (41). As a result, workers can easily transport and install the casing (60).

[0009] In a second embodiment, the casing (60) has a first side (63) and a second side (64) in the first embodiment. The first side (63) has an access opening (A) to a first space (S1) in which a refrigerant unit (U) is housed. The second side (64) is located on the opposite side of the casing (60) from the first side (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 access opening (A).

[0010] 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 access port (A). 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.

[0011] 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).

[0012] 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 taken out of the casing (60) through the access port (A).

[0013] In the fourth aspect, as in the third aspect, the water-side connection portion (C1, C2) is closer to the first side surface (63) than to the second side surface (64).

[0014] In the fourth embodiment, the water-side connection points (C1, C2) are closer to the access port (A), making it easier for the worker to attach and detach the water-side connection points (C1, C2).

[0015] A fifth aspect is that, in the third or fourth aspect, the heat transfer medium side connection portion (C3, C4) is closer to the first side portion (63) than to the second side portion (64).

[0016] In the fifth embodiment, the heat transfer fluid side connection parts (C3, C4) are closer to the access port (A), so that the worker can easily attach and detach the heat transfer fluid side connection parts (C3, C4).

[0017] The sixth embodiment is one of the second to fifth embodiments, wherein the hot water supply unit (20) further comprises a first external connection part (83, 84, 85, 86) provided outside the casing (60) to which water pipes (93, 94, 95, 96) of the water circuit (W) are connected, and a second external connection part (81, 82) provided outside the casing (60) to which refrigerant pipes (91, 92) of the heat transfer medium circuit (R2, 100) are connected. The second external connection part (81, 82) is closer to the first side surface (63) than the first external connection part (83, 84, 85, 86).

[0018] Generally, connecting refrigerant pipes (91, 92) is more difficult than connecting water pipes (93, 94, 95, 96). In the sixth embodiment, the second outer connection (81, 82) is closer to the first side (63) than the first outer connection (83, 84, 85, 86), making it easier for the worker to access the second outer connection (81, 82). Therefore, the worker can easily connect the refrigerant pipes (91, 92).

[0019] In the seventh aspect, in the sixth aspect, the second outer connecting portion (81, 82) is closer to the first side surface (63) than to the second side surface (64). The first outer connecting portion (83, 84, 85, 86) is closer to the second side surface (64) than to the first side surface (63).

[0020] In the seventh embodiment, the second outer connection parts (81, 82) and the first outer connection parts (83, 84, 85, 86) are separated in the opposing directions of the first side surface (63) and the second side surface (64). Therefore, the worker can easily perform the connection work of water pipes (93, 94, 95, 96) and refrigerant pipes (91, 92).

[0021] The eighth aspect is that, in any one of the third to fifth aspects, the hot water supply unit (20) 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.

[0022] In the eighth 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.

[0023] The ninth embodiment is one of the first to eighth embodiments, in which the hot water supply unit further comprises an electrical unit (71) housed within a casing (60). The electrical unit (71) is located below the tank (41).

[0024] In the ninth embodiment, the center of gravity of the hot water supply unit (20) is further lowered by positioning the electrical equipment unit (71) below the tank (41).

[0025] The tenth embodiment is one of the first to ninth 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.

[0026] In the tenth embodiment, the hot water supply unit performs a so-called dual refrigeration cycle.

[0027] 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 schematic plan view showing the arrangement of equipment in the first space of the hot water supply unit of Modification 1. Figure 6 is a piping diagram of the hot water supply system of Modification 2.

[0028] 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.

[0029] (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.

[0030] 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.

[0031] 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 therefore have a low environmental impact. Propane ignites at temperatures below 500°C. Flammable refrigerants may also be methane (R50), ethane (R170), butane (R600), or isobutane (R600a). The flammable refrigerant may not be a highly flammable refrigerant, but a slightly flammable refrigerant. Slightly flammable refrigerants may include difluoromethane (R32) or tetrafluoropropene (HFO-1234yf). The first refrigerant may be a single refrigerant consisting of one of the refrigerants described above, or a mixed refrigerant consisting of one of the refrigerants described above and one or more other refrigerants.

[0032] 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), 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 using the first refrigerant circuit (R1) and the second refrigerant circuit (R2).

[0033] (1-2) Outdoor Unit The outdoor unit (10) has 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 the inhaled refrigerant and discharges the 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) reduces the pressure of the refrigerant. The four-way switching valve (14) switches between a first state shown by the solid line in Figure 1 and a second state shown by the dashed line in Figure 1. The second accumulator (15) stores the liquid refrigerant before it is drawn into the second compressor (11).

[0034] (1-3) Circuit configuration of the hot water supply unit The hot water supply unit (30) has the entirety of the first refrigerant circuit (R1). The hot water supply unit (20) has 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) as components of the first refrigerant circuit (R1). 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) causes heat exchange 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 reduction mechanism for reducing the pressure of the refrigerant. The first accumulator (25) stores liquid refrigerant before it is drawn into the first compressor (21). The refrigerant heat exchanger (22) and the first water heat exchanger (23) are composed of, for example, plate heat exchangers.

[0035] The hot water supply unit (20) has a part of the second refrigerant circuit (R2). In addition to the first water heat exchanger (23) described above, the hot water supply unit (20) has a second water heat exchanger (26) as an element 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 composed of, for example, a plate heat exchanger.

[0036] 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).

[0037] 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).

[0038] 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.

[0039] 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.

[0040] 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).

[0041] 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.

[0042] 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).

[0043] 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).

[0044] The heating-side flow path (52) is connected to the utilization-side heat exchanger (6) of the heating device (5). The utilization-side heat exchanger (6) heats the air in the target space (indoor space). The utilization-side heat exchanger (6) is composed of a fin-and-tube type heat exchanger or a radiation panel. The utilization-side heat exchanger (6) is composed 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 portion of the target space.

[0045] 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 the hot water heated by 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 dissipated heat in the utilization-side heat exchanger (6) to the main flow path (50).

[0046] The hot water supply unit (20) further has a heater unit (54) and an expansion tank (55) as equipment elements of the water circuit (W). The heater unit (54) is provided in the main flow path (50) and auxiliary heats the water in the water circuit (W). The expansion tank (55) communicates with the main flow path (50) and alleviates the increase in the water pressure of the water circuit (W).

[0047] (2) Structure of the hot water supply unit The structure of the hot water supply unit (20) will be described while referring to FIGS. 1 to 4. In the following description, the terms related to up, down, front, back, right, and left are based on the directions indicated by the arrows in FIG. 2.

[0048] (2-1) Casing As shown in FIG. 2, the hot water supply system (1) has a casing (60) disposed in the indoor space (I). The indoor space (I) is a space formed inside a building, including not only the space of a living room but also non-living room spaces such as corridors, basements, warehouses, and garages. The casing (60) is installed on the floor surface of the indoor space (I). The casing (60) is formed in a hollow box shape. The casing (60) has a rectangular parallelepiped outer shape. The vertical height of the casing (60) is greater than the front-to-back length and the 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 plate (63) constitutes the front surface, which is the first side surface of the casing (60), and the rear plate (64) constitutes the rear surface, which is the second side surface of the casing (60). The right plate (65) constitutes the right surface, which is the third side surface of the casing (60), and the left plate (66) constitutes the left surface, which is the fourth side surface of the casing (60).

[0049] Inside the casing (60), a partition plate (67) is provided. 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 at the lower part of the casing (60). The second space (S2) is formed from the middle part to the upper part of the casing (60). The first space (S1) and the second space (S2) are formed in a rectangular parallelepiped shape. The height of the second space (S2) is greater than the height of the first space (S1). A tank (41) is disposed in the second space (S2).

[0050] In the installed state of the casing (60), a working space (S3) is secured in front of the casing (60). An access port (A) is formed at the lower part of the front plate (63) of the casing (60). A lid (68), which is a part of the front plate (63), is detachably attached to the access port (A). An operator can access the first space (S1) inside the casing (60) through the access port (A) from the working space (S3).

[0051] (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 of these pipes. Therefore, the position and shape of these pipes and connections are not limited to those shown in Diagram 3. The equipment of the hot water supply unit (20) described above is arranged in the first space (S1). As shown in Diagram 3, the refrigerant unit (U) having a first refrigerant circuit (R1) is arranged in the first space (S1). 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 elemental components of the first refrigerant circuit (R1).

[0052] 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 access port (A). The first compressor (21) is visible from outside the casing (60) through the access port (A) when the opening / closing cover (68) is removed. The refrigerant unit (U) is located below the tank (41). The refrigerant unit (U) overlaps with the tank (41) in the vertical direction.

[0053] 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).

[0054] 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 access opening (A) along the bottom plate (62). It is preferable that the bottom plate (62) is provided with a guide member that guides the support member (70) in the front-rear direction.

[0055] An electrical component unit (71) is provided in the first space (S1). The electrical component unit (71) is positioned below the tank (41). The electrical component unit (71) overlaps with the tank (41) in the vertical direction.

[0056] 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 access opening (A). When the opening / closing cover (68) is removed, the electrical components unit (71) is visible from outside the casing (60) through the access opening (A).

[0057] 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) penetrate the partition plate (67) and extend vertically through the first space (S1).

[0058] 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).

[0059] The first connection part (C1) and the second connection part (C2) constitute a water-side connection part that detachably connects the first water heat exchanger (23) and the water circuit (W). As shown in Figure 1, the first connection part (C1) connects the water piping on the inflow side of the fourth flow path (P4) of the first water heat exchanger (23) to the water circuit (W). The second connection part (C2) connects the water piping on the outflow side of the fourth flow path (P4) of the first water heat exchanger (23) to the water circuit (W). The first connection part (C1) is closer to the front plate (63) than to the rear plate (64). The second connection part (C2) is closer to the front plate (63) than to the rear plate (64). The first connection part (C1) and the second connection part (C2) are arranged side by side in the left-right direction along the back of the electrical component unit (71). The first connection (C1) and the second connection (C2) may be directly connected to the first water heat exchanger (23) and the water circuit (W), or they may be indirectly connected via piping.

[0060] The third connection (C3) and the fourth connection (C4) constitute the heat transfer medium side connection that detachably connects the refrigerant heat exchanger (22) and the second refrigerant circuit (R2). As shown in Figure 1, the third connection (C3) connects the gas-side refrigerant piping of the second flow path (P2) of the refrigerant heat exchanger (22) to the second refrigerant circuit (R2). The third connection (C3) is closer to the front plate (63) than to the rear plate (64). 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 fourth connection (C4) is located behind the third connection (C3). The third connection (C3), like the fourth connection (C4), may be located closer to the front plate (63) than to the rear plate (64). The third connection point (C3) and the fourth connection point (C4) may be directly connected to the refrigerant heat exchanger (22) and the second refrigerant circuit (R2), or they may be indirectly connected via piping.

[0061] In the first space (S1), the components of the water circuit (W) are arranged behind the refrigerant unit (U) and connection space (75). A water circuit side space (76) is formed. The water circuit side space (76) is formed towards the rear of the first space (S1). 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.

[0062] The inlet pipe (51a) and outlet pipe (51b) pass through the partition plate (67) and connect to the internal heat exchanger (42) in the tank (41). The supply pipe (52a) and return pipe (52b) pass through the partition plate (67) and extend vertically through the first space (S1).

[0063] 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).

[0064] (2-3) As shown in the layout diagrams 2 and 4 of the upper plate connection section, 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).

[0065] Specifically, the first pipe (31) is connected to the lower end of the first refrigerant fitting (81), and the third pipe (33) is connected to the base end of the second refrigerant fitting (82). The water supply pipe (43) is connected to the lower end of the first water fitting (83), the hot water outlet pipe (44) is connected to the lower end of the second water fitting (84), the supply pipe (52a) is connected to the lower end of the third water fitting (85), and the return pipe (52b) is connected to the lower end of the fourth water fitting (86).

[0066] 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 upper end of the first refrigerant fitting (81) is connected to the first gas-side connecting pipe (91) which connects to the outdoor unit (10). The upper end of the second refrigerant fitting (82) is connected to the second liquid-side connecting pipe (92) which connects to the outdoor unit (10). The upper end of the first water fitting (83) is connected to the first water pipe (93) for water supply. The upper end of the second water fitting (84) is connected to the second water pipe (94) for hot water supply. The upper end of the third water fitting (85) is connected to the third water pipe (95) on the inlet side of the heating device (5). The upper end of the fourth water fitting (86) is connected to the fourth water pipe (96) on the outlet side of the heating device (5).

[0067] The first water fitting (83), the second water fitting (84), the third water fitting (85), and the fourth water fitting (86) constitute the first outer connection section, and the first refrigerant fitting (81) and the second refrigerant fitting (82) constitute the second outer connection section. The second outer connection sections (81, 82) are closer to the front plate (63), which is the first side, than the first outer connection sections (83, 84, 85, 86). The second outer connection sections (81, 82) are closer to the front plate (63) than the rear plate (64), which is the second side (64). The first refrigerant fitting (81) and the second refrigerant fitting (82) are arranged left and right along the front plate (63). The first water fitting (83), the second water fitting (84), the third water fitting (85), and the fourth water fitting (86) are arranged left and right along the rear plate (64). These water fittings are arranged at equal intervals.

[0068] (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.

[0069] 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).

[0070] 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).

[0071] 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).

[0072] 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).

[0073] 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.

[0074] (4) Workers' work After transporting the hot water supply unit (20) to the site, the workers install the hot water supply unit (20) in the indoor space (I). At this time, the refrigerant unit (U) and tank (41) are housed inside the casing (60) of the hot water supply unit (20). Since water has not yet been supplied to the tank (41), the tank (41) is empty. The weight of the hot water supply unit (20) is relatively greater than the weight of the tank (41).

[0075] The refrigerant unit (U) is positioned in the first space (S1) below the tank (41). This lowers the center of gravity of the hot water supply unit (20), making it easier for workers to transport and install the hot water supply unit (20). In particular, since the casing (60) has a greater vertical height than its front-to-back length and left-to-right width, lowering the vertical center of gravity significantly improves work efficiency.

[0076] In addition, since other equipment different from the refrigerant unit (U) is located below the tank (41), the center of gravity of the hot water supply unit (20) can be lowered even further. The other equipment includes a second water heat exchanger (26), an electrical unit (71), a pump (40), a three-way valve (53), a heater unit (54), an expansion tank (55), a drain valve, a ball valve, a flow sensor, and a filter.

[0077] After the hot water supply unit (20) is installed in the indoor space (I), 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). Connecting these refrigerant pipes is more difficult than connecting the water pipes. This is because refrigerant pipes require more precautions against leakage than water pipes. The first refrigerant fitting (81) and the second refrigerant fitting (82) are located closer to the front plate (63) than the water fittings (83, 84, 85, 86), so the worker can easily connect the refrigerant pipes from the work space (S3) side.

[0078] Each refrigerant fitting (81, 82) is closer to the front plate (63) than to the rear plate (64), and each water fitting (83, 84, 85, 86) is closer to the rear plate (64) than to the front plate (63). As a result, the spacing between the refrigerant fittings (81, 82) and the water fittings (83, 84, 85, 86) is increased, making it easier to connect the piping of these fittings.

[0079] 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 opening / closing cover (68) from the casing (60) to expose the access port (A). 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 access port (A). 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 if the disconnection were 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 a major problem.

[0080] The worker moves the support member (70) forward through the access opening (A). This allows the refrigerant unit (U) to be removed from the casing (60) along with the support member (70) through the access opening (A). The worker performs maintenance on the 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) along with the support member (70) to its original position. Then, the worker reconnects the first connection (C1), second connection (C2), third connection (C3), and fourth connection (C4).

[0081] (5) Effects of the embodiment (5-1) The refrigerant unit (U) is positioned below the tank (41). In this configuration, the center of gravity of the hot water supply unit (20) can be lowered, so that workers can easily transport and install the hot water supply unit (20).

[0082] By positioning the electrical components unit (71) below the tank (41), the center of gravity of the hot water supply unit (20) is further lowered.

[0083] (5-2) The front panel (63) has an access port (A) to a first space (S1) in which the refrigerant unit (U) is housed. The hot water supply unit (20) is equipped with a support member (70) that supports the refrigerant unit (U) and can be moved in and out through the access port (A). In this configuration, the worker can remove the refrigerant unit (U) to the outside of the casing (60). The worker can move the refrigerant unit (U) to the outdoor space and then perform maintenance on the refrigerant unit (U). Therefore, the risk caused by leakage of flammable refrigerant can be reduced.

[0084] (5-3) The refrigerant unit (U) has a water-side connection part (C1, C2) that detachably connects the first water heat exchanger (23) to the water circuit (W), and a heat transfer medium-side connection part (C3, C4) that detachably connects the refrigerant heat exchanger (22) to the second refrigerant circuit (R2). In this configuration, by disconnecting these connection parts (C1, C2, C3, C4), the first refrigerant circuit (R1) can be removed from the casing (60) while remaining in a closed circuit. Therefore, leakage of flammable refrigerant can be suppressed when removing the refrigerant unit (U).

[0085] (5-4) The water-side connection points (C1, C2) are closer to the front plate (63) than to the rear plate (64). Therefore, workers can easily disconnect and connect the water-side connection points (C1, C2). The heat transfer fluid-side connection point (strictly speaking, the third connection point) is closer to the front plate (63) than to the rear plate (64). Therefore, workers can easily disconnect and connect the third connection point (C3).

[0086] (5-5) The second outer connection points (81, 82) are closer to the first side surface (63) than the first outer connection points (83, 84, 85, 86). Therefore, workers can easily connect the refrigerant piping to the second outer connection points (81, 82).

[0087] The second outer connection points (81, 82) are closer to the front plate (63) than to the rear plate (64). The first outer connection points (83, 84, 85, 86) are closer to the front plate (63) than to the rear plate (64). In this configuration, the second outer connection points (81, 82) and the first outer connection points (83, 84, 85, 86) are separated in the front-rear direction, so the space around the second outer connection points (81, 82) and the first outer connection points (83, 84, 85, 86) is increased. As a result, workers can easily connect refrigerant piping to the second outer connection points (81, 82) and water piping to the first outer connection points (83, 84, 85, 86).

[0088] (6) Modified Examples The above-described embodiment may also have the following modified configuration. The differences from the embodiment will be explained below.

[0089] (6-1) Modification 1 As shown in Figure 5, the hot water supply unit (20) of Modification 1 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).

[0090] 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.

[0091] (6-2) Modified Example 2 As shown in Figure 6, the hot water supply system (1) of Modified Example 2 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).

[0092] (7) 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).

[0093] 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.

[0094] 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.

[0095] 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.

[0096] The refrigerant unit (U) and the electrical component unit (71) do not necessarily have to overlap the tank (41) vertically. The refrigerant unit only needs to be positioned lower than the bottom edge of the tank (41). The electrical component unit (71) may be located in the second space (S2). The partition plate (67) shields the electrical component unit (71) from the third connection part (C3) and the fourth connection part (C4), thus preventing sparks from flying onto the electrical component unit during operations such as brazing or welding.

[0097] The connection space (75) does not have to be formed behind the electrical component unit (71), but may be formed, for example, above, in front of, or to the side of the electrical component unit (71).

[0098] The first connection (C1), second connection (C2), third connection (C3), and fourth connection (C4) may be located near the access port (A). The first connection (C1), second connection (C2), third connection (C3), and fourth connection (C4) may be arranged side by side in the left-right direction.

[0099] 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).

[0100] The expansion mechanism does not have to be an expansion valve; it may be a capillary tube or an inflator.

[0101] (8) 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.

[0102] 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.

[0103] As described above, this disclosure is useful for hot water supply units.

[0104] 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 63 Front plate (first side) 64 Rear plate (second side) 70 Support member 71 Electrical components unit 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 A 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 (heat transfer medium circuit) 100 Primary circulation circuit (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) includes 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 below the tank (41).

2. The hot water supply unit according to claim 1, wherein the casing (60) has a first side surface (63) having an access port (A) for 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 access port (A).

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 water-side connection portion (C1, C2) is closer to the first side surface (63) than to the second side surface (64).

5. The hot water supply unit according to claim 3 or 4, wherein the heat transfer medium side connection portion (C3, C4) is closer to the first side surface (63) than to the second side surface (64).

6. A hot water supply unit according to any one of claims 2 to 5, further comprising: a first external connection part (83, 84, 85, 86) provided outside the casing (60) to which the water pipes (93, 94, 95, 96) of the water circuit (W) are connected; and a second external connection part (81, 82) provided outside the casing (60) to which the refrigerant pipes (91, 92) of the heat transfer medium circuit (R2, 100) are connected, wherein the second external connection part (81, 82) is closer to the first side surface (63) than the first external connection part (83, 84, 85, 86).

7. The hot water supply unit according to claim 6, wherein the second outer connection portion (81, 82) is closer to the first side surface (63) than the second side surface (64), and the first outer connection portion (83, 84, 85, 86) is closer to the second side surface (64) than the first side surface (63).

8. 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 portions (C3, C4) and the refrigerant circuit (R1) from each other.

9. The hot water supply unit according to any one of claims 1 to 8, further comprising an electrical component unit (71) housed within the casing (60), wherein the electrical component unit (71) is positioned below the tank (41).

10. The hot water supply unit according to any one of claims 1 to 9, wherein the heat transfer medium circuit (R2, 100) is a second refrigerant circuit (R2) that performs a refrigeration cycle using a second refrigerant.

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