Hot water supply tank unit, and heat-pump water heater

Abstract

Provided are a hot water supply tank unit and a heat-pump water heater that can avoid a circumstance in which water affects an electrical circuit positioned below a drain pan, even if a drainage port in the drain pan becomes clogged and the drain pan overflows. A hot water supply tank unit (3) includes: a hot water supply tank (12) mounted on a bottom plate (85) of a housing (81); a water circuit (41) accommodated above the hot water supply tank (12) inside the housing (81); a drain pan (82) disposed between the water circuit (41) and the hot water supply tank (12); and a control unit (6) accommodated below the drain pan (82) inside the housing (81) and in proximity to any one of the side plates. The drain pan (82) includes a bulging portion (151) in poximity to at least one of other side plates (88) of the side plates (88), and a non-bulging portion (152) farther from the at least one other side plate (88) than the bulging portion (151). Water overflowing from the drain pan (82) is guided to the lower side inside the housing (81) via an overflow path (153) which is a gap between the non-bulging portion (152) and the side plate (88).

Description

TECHNICAL FIELD

[0001] Embodiments of the present invention relate to a hot water supply tank unit and a heat pump water heater.BACKGROUND

[0002] There is known a water heater including a tank, a main frame that is disposed directly above the tank to support a circuit that heats a heat medium by a heat pump, and a support plate that is interposed between the tank and the main frame to support the main frame. The support plate is provided inside a receiving portion that supports the main frame, and has a recessed portion for receiving drainage from various devices and piping through which water flows disposed thereabove, and a drain port that opens at a lowest portion of the recessed portion and penetrates the support plate. This drain port is connected to a drain pipe that discharges drainage to the outside of the water heater.PRIOR ART DOCUMENTPATENT DOCUMENT

[0003] Patent Document 1: European Patent Application Publication No. 3462103SUMMARYPROBLEMS TO BE SOLVED BY INVENTION

[0004] If the drain port of the support plate or the drain pipe becomes clogged, the drainage that accumulates in the recessed portion of the support plate overflows from the peripheral edge of the support plate. In a case where an electric circuit is disposed below the support plate, the water that overflows from the support plate wets the electric circuit below the support plate and inhibits normal operation of the water heater.

[0005] In view of the foregoing, the present invention aims to provide a hot water supply tank unit and a heat pump water heater that can prevent water from wetting an electric circuit disposed below a drain pan even if a drain port of the drain pan becomes clogged and the drain pan overflows.MEANS FOR SOLVING PROBLEM

[0006] In order to solve the above-mentioned problem, a hot water supply tank unit according to an embodiment of the present invention includes: a housing including a bottom plate, a frame including a plurality of pillar members rising from the bottom plate, and a plurality of side plates hung across the adjacent pillar members; a hot water supply tank mounted on the bottom plate and accommodated in a lower side inside the housing; a water circuit accommodated above the hot water supply tank inside the housing and through which water flows; a drain pan disposed between the water circuit and the hot water supply tank and supported by the frame and the hot water supply tank; and an electric circuit accommodated below the drain pan inside the housing and in proximity to any one of the plurality of side plates. The drain pan includes a bulging portion in proximity to at least one of other side plates of the plurality of side plates, and a non-bulging portion farther from the at least one other side plate than the bulging portion. Water overflowing from the drain pan is guided to the lower side inside the housing via an overflow path which is a gap between the non-bulging portion of the drain pan and the side plate.

[0007] The water circuit of the hot water supply tank unit according to the embodiment of the present invention preferably includes a water heat exchanger that exchanges heat between a refrigerant and the water, and a circulation circuit that circulates the water whose heat is exchanged by the water heat exchanger.

[0008] The hot water supply tank unit according to the embodiment of the present invention preferably includes a refrigeration circuit that is disposed directly above the drain pan and circulates the refrigerant whose heat is exchanged by the water heat exchanger.

[0009] Preferably, the drain pan of the hot water supply tank unit according to the embodiment of the present invention is a formed product of a foaming material, and a gap is formed between the bulging portion and the side plate.

[0010] Preferably, the electric circuit of the hot water supply tank unit according to the embodiment of the present invention is disposed on the front surface, and the overflow path is disposed on at least one of the back surface, the right side surface, and the left side surface.

[0011] The drain pan of the hot water supply tank unit according to the embodiment of the present invention preferably includes an upstream overflow path that is provided in the non-bulging portion and continuous with the overflow path, and guides water collected in the drain pan to the overflow path.

[0012] The hot water supply tank unit according to the embodiment of the present invention preferably includes the bottom plate including a handle opening, a resin handle disposed in the housing and provided in the handle opening, a metal handle cover disposed in the housing and covering the handle, and a fastening member that fixes the handle cover to the handle.EFFECTS OF INVENTION

[0013] According to the present invention, it is possible to provide a hot water supply tank unit and a heat pump water heater that can prevent water from wetting an electric circuit disposed below a drain pan even if a drain port of the drain pan becomes clogged and the drain pan overflows.BRIEF DESCRIPTION OF DRAWINGS

[0014] Fig. 1 is a system configuration diagram of a heat pump water heater according to an embodiment of the present invention. Fig. 2 is a perspective view of a hot water supply tank unit according to the embodiment of the present invention. Fig. 3 is a back view of the hot water supply tank unit according to the embodiment of the present invention. Fig. 4 is a perspective view of the hot water supply tank unit according to the embodiment of the present invention in which an outer plate is removed. Fig. 5 is a perspective view of the hot water supply tank unit according to the embodiment of the present invention in which the outer plate, a refrigeration circuit, and a heat medium circulation circuit are removed. Fig. 6 is a planar sectional view of a housing and a drain pan of the hot water supply tank unit according to the embodiment of the present invention. Fig. 7 is a partial perspective view of the housing and the drain pan of the hot water supply tank unit according to the embodiment of the present invention. Fig. 8 is a longitudinal sectional view of the drain pan and a hot water supply tank of the hot water supply tank unit according to the embodiment of the present invention. Fig. 9 is a plan view of a bottom plate of the hot water supply tank unit according to the embodiment of the present invention. Fig. 10 is a perspective view of the bottom plate of the hot water supply tank unit according to the embodiment of the present invention. DETAILED DESCRIPTION

[0015] Embodiments of a hot water supply tank unit and a heat pump water heater according to the present invention will be described with reference to Fig. 1 to Fig. 10. The same reference signs are given to identical or equivalent components in each figure.

[0016] Fig. 1 is a system configuration diagram of the heat pump water heater according to the embodiment of the present invention.

[0017] As illustrated in Fig. 1, a heat pump water heater 1 according to the present embodiment heats supply water supplied from the outside using the heat of outside air to store the hot water in a hot water supply tank 12, and supplies the hot water in the hot water supply tank 12 to the outside if necessary. Note that the supply water supplied from the outside is generally tap water supplied through water pipes.

[0018] The heat pump water heater 1 includes: an outdoor unit 2 that serves as a heat source unit for exchanging heat between outdoor air and a refrigerant; a hot water supply tank unit 3 that exchanges heat between circulating water as a use-side heat medium and the refrigerant to exchange heat between the circulating water and supply water and heat the supply water to boiling point; a remote controller 5 as an input device that accepts operations from the user; and a control unit 6 that controls the outdoor unit 2 and the hot water supply tank unit 3 on the basis of the operations input to the remote controller 5. Note that the circulating water which is the use-side heat medium is not limited to water, and may be other heat mediums such as antifreeze.

[0019] The heat pump water heater 1 circulates the refrigerant between the outdoor unit 2 and the hot water supply tank unit 3, exchanges heat between the refrigerant and the circulating water in a water heat exchanger 11 in the hot water supply tank unit 3, and exchanges heat between the circulating water and the supply water in a hot water supply tank 12 in the hot water supply tank unit 3.

[0020] The water circulating inside the hot water supply tank unit 3 is used for heating, so-called boiling up, of the supply water stored in the hot water supply tank 12. The supply water heated in the hot water supply tank 12, i.e., hot water is supplied to hot water supply destinations, such as the washroom, the kitchen, and the bathroom.

[0021] In general, the outdoor unit 2 is installed outside and the hot water supply tank unit 3 is installed inside. The outdoor unit 2 and the hot water supply tank unit 3 are connected by crossover pipes 17 and 18 that refrigerant piping 13 includes and communication lines (not illustrated). That is, only the refrigerant flows between the outdoor unit 2 and the hot water supply tank unit 3, so that the heat pump water heater 1 does not need piping for water supply outside. Accordingly, the heat pump water heater 1 can avoid freezing water in outdoor piping for water supply during low temperatures in winter.

[0022] The heat pump water heater 1 heats the circulating water and circulates the circulating water of a first temperature such as 40 to 50 degrees Celsius to an outside device without passing through the hot water supply tank 12. The outside device is, for example, a radiator 22 (radiator 22) for an underfloor heating system or an indoor unit 23 for an air conditioning system. The first temperature depends on the type of the refrigerant. In a case of circulating an R410A refrigerant between the outdoor unit 2 and the hot water supply tank unit 3, the first temperature reaches a maximum of around 55 degrees Celsius. If an R32 refrigerant or a CO2 refrigerant is used, the first temperature can be raised even higher.

[0023] The heat pump water heater 1 can be configured to heat supply water to a second temperature higher than the first temperature, such as around 70 degrees Celsius, by using a combination of heat exchange between the refrigerant and circulating water in the water heat exchanger 11 and heating of the supply water by a backup heater 31 installed the downstream side of the water heat exchanger 11 in the hot water supply tank 12, and store the hot water in the hot water supply tank 12.

[0024] The heat pump water heater 1 includes a refrigeration circuit 32. The heat source of the refrigeration circuit 32 is outside air. The refrigeration circuit 32 includes a compressor 35 that compresses and discharges the refrigerant, an air heat exchanger 36 that serves as an evaporator, an expansion valve 37, the water heat exchanger 11 that serves as a condenser, and the refrigerant piping 13 that connects the compressor 35, the air heat exchanger 36, the expansion valve 37, and the water heat exchanger 11 to circulate the refrigerant. The water heat exchanger 11 is a plate-type heat exchanger or a heat exchanger with double pipes that conducts heat exchange between the refrigerant and circulating water. The refrigeration circuit 32 transfers heat from the air heat exchanger 36, which is a low-temperature part, to the water heat exchanger 11, which is a high-temperature part, by means of the circulating refrigerant. The refrigeration circuit 32 heats circulating water by the heat of the high-temperature refrigerant circulating through the water heat exchanger 11.

[0025] The refrigeration circuit 32 includes: a four-way valve 38 that sends the refrigerant discharged from the compressor 35 to one of the air heat exchanger 36 and the water heat exchanger 11, and then sends the refrigerant that has passed through the other of the air heat exchanger 36 and the water heat exchanger 11 back to the compressor 35; and an accumulator 39 provided in the refrigerant piping 13 between the four-way valve 38 and the compressor 35.

[0026] The water heat exchanger 11 and a part of the refrigerant piping 13 are accommodated in the hot water supply tank unit 3. Other components of the refrigeration circuit 32 are accommodated in the outdoor unit 2.

[0027] In a case where circulating water is heated by the refrigeration circuit 32, the air heat exchanger 36 functions as an evaporator (also referred to as "heat absorber"), and the water heat exchanger 11 functions as a condenser (also referred to as "radiator").

[0028] The compressor 35 compresses the refrigerant, increases the pressure, and discharges it. It is preferable that the compressor 35 can change its operating frequency using known inverter control. Increasing the speed of the compressor 35 increases the amount of heat transferred to the high-temperature part, and decreasing the speed of the compressor 35 decreases the amount of heat transferred to the high-temperature part.

[0029] As the expansion valve 37, for example, an electronically controlled expansion valve (pulse motor valve, PMV) that can adjust the valve opening is used.

[0030] The refrigerant piping 13 connects the compressor 35, the accumulator 39, the four-way valve 38, the air heat exchanger 36, the expansion valve 37, and the water heat exchanger 11.

[0031] The four-way valve 38 switches the direction of flow of the refrigerant circulating through the compressor 35, the air heat exchanger 36, the expansion valve 37, and the water heat exchanger 11. In the case where circulating water is heated by the refrigeration circuit 32, the four-way valve 38 circulates the refrigerant discharged from the compressor 35 in the order of the water heat exchanger 11, the expansion valve 37, and the air heat exchanger 36 (flow of refrigerant indicated by solid line in Fig. 1).

[0032] When heating the circulating water, the refrigeration circuit 32 that is a refrigeration cycle discharges a compressed high-temperature high-pressure refrigerant from the compressor 35. The refrigerant is sent to the hot water supply tank unit 3 through the four-way valve 38 and the crossover pipe 15 to enter the water heat exchanger 11. The water heat exchanger 11 heats the circulating water passing through the water heat exchanger 11 with the refrigerant passing through the water heat exchanger 11. The refrigerant having heated the circulating water in the water heat exchanger 11 is cooled and becomes a high-pressure liquid state. That is, when heating the circulating water by the refrigerant, the water heat exchanger 11 functions as a radiator. The refrigerant having passed through the water heat exchanger 11 returns to the outdoor unit 2 through the crossover pipe 16, passes through the expansion valve 37 to be decompressed and become a low-pressure gas-liquid two-phase refrigerant, and reaches the air heat exchanger 36. The air heat exchanger 36 is ventilated with outside air by a blower (not illustrated). This outside air heats the refrigerant flowing through the air heat exchanger 36. At this time, the air heat exchanger 36 functions as a heat absorber that evaporates the refrigerant and turns it into a gaseous state. The refrigerant having passed through the air heat exchanger 36 and become a gas is sucked into the compressor 35.

[0033] When the outside temperature drops, the surface of the outdoor air heat exchanger 36 is frosted. Therefore, the refrigeration circuit 32 switches the direction of the flow of the refrigerant in the refrigerant piping 13 using the four-way valve 38 to perform defrosting. When performing defrosting, the heat pump water heater 1 reverses the four-way valve 38 to create a refrigerant flow in the opposite direction to the refrigerant flow that heats the circulating water in the refrigeration circuit 32. In the case of defrosting, the four-way valve 38 circulates the refrigerant discharged from the compressor 35 in the order of the air heat exchanger 36, the expansion valve 37, and the water heat exchanger 11 (flow of refrigerant indicated by broken line in Fig. 1).

[0034] When defrosting, the air heat exchanger 36 functions as a condenser, and the water heat exchanger 11 functions as an evaporator. The heat pump water heater 1 cools the circulating water by circulating the refrigerant in the same direction as defrosting, and takes heat from the supply water in the hot water supply tank 12. However, the frequency of defrosting is low, and the duration of defrosting is short, lasting only about 10 minutes. Accordingly, defrosting only slightly lowers the temperature of water stored in the hot water supply tank 12, and does not largely affect the use of hot water.

[0035] The hot water supply tank unit 3 includes the water heat exchanger 11 that is a part of the refrigeration circuit 32 and heats circulating water with the circulating refrigerant, the hot water supply tank 12 that can store approximately 100 to 200 liters of water, and a heat medium circulation circuit 41 that is a water circuit circulating the circulating water heated by the water heat exchanger 11 between the water heat exchanger 11 and the hot water supply tank 12. The hot water supply tank unit 3 is also referred to as a water heat exchange unit (hydro unit).

[0036] The heat medium circulation circuit 41 includes the use side of the water heat exchanger 11, circulating water piping 42 that circulates circulating water which is the use-side heat medium, a first pump 43 that circulates the circulating water, the backup heater 31 that further heats the circulating water in addition to the heat exchange by the water heat exchanger 11, an expansion tank 45 that absorbs expansion (increase in volume) of the heated circulating water, and a flow rate sensor 46 that measures the flow rate of the circulating water and outputs the flow rate to the control unit 6. The circulating water is circulated in one direction in the heat medium circulation circuit 41.

[0037] The circulating water heated in the water heat exchanger 11 is sucked into the driving first pump 43 and is discharged toward the hot water supply tank 12. The circulating water whose temperature has dropped after heating the supply water in the hot water supply tank 12 is returned to the water heat exchanger 11. The circulating water having returned to the water heat exchanger 11 is heated again by the refrigerant circulating through the refrigeration circuit 32. The circulating water heated by the water heat exchanger 11 is sucked into the first pump 43 again.

[0038] The hot water supply tank 12 stores supply water heated and boiled up by the circulating water circulating through the use-side heat medium circulation circuit 41, that is, hot water, and supplies it to the user as required. The hot water supply tank 12 includes a stainless steel tank 51 that can store supply water, a water supply pipe 53 that includes an outlet 52 disposed in a bottom portion inside the tank 51 and pours the supply water into the tank 51, a coil 55 provided in the tank 51 to circulate the circulating water that heats the supply water in the tank 51, a hot water supply pipe 56 that guides the hot water, which is the supply water that has been heated inside the tank 51, to the outside of the tank 51, and a heat insulation material 58 that covers most of an outer surface of the tank 51.

[0039] The tank 51 is airtight, except for the hot water supply pipe 56 and the water supply pipe 53. When hot water is used at the hot water supply destination which is connected to the hot water supply pipe 56, supply water is fed into the tank 51 from the water supply pipe 53 to replenish the amount of hot water supplied. As a result, the tank 51 is filled with water. The hot water supply pipe 56 that supplies the hot water from the tank 51 is provided in a top portion of the tank 51. In general, the hot water supply tank 12 supplies hot water from the tank 51 to the hot water supply destination by the water pressure of tap water acting on a water pipe, which is the connection destination, of the water supply pipe 53. For this reason, the same amount of water as that supplied via the hot water supply pipe 56 is supplied from the water supply pipe 53 into the tank 51.

[0040] The coil 55 includes a circulating water introduction portion 55a that penetrates an upper mirror plate 122 which is the ceiling of the tank 51 in the up-down direction to enter the tank 51 and extends downward inside the tank 51 in a straight line, a spiral portion 55b that is wound in a spiral shape subsequent to the circulating water introduction portion 55a, and a circulating water returning portion 55c that extends upward inside the tank 51 in a straight line from the end of the spiral portion 55b and penetrates the upper mirror plate 122 in the up-down direction to protrude out of the tank 51.

[0041] The heat insulation material 58 that prevents the temperature of hot water in the tank 51 from dropping by reducing direct heat dissipation to the atmosphere is provided around the hot water supply tank 12. The heat insulation material 58 is either expanded polystyrene or expanded polyurethane foam, which has better heat insulation performance than expanded polystyrene. Vacuum heat insulation material, which has even better heat insulation properties, can also be used. Note that no heat insulation material is provided in a lower portion of the tank 51 where there is little need for heat retention.

[0042] The heat pump water heater 1 includes, in addition to a temperature sensor (not illustrated) that measures a representative value of the temperature of hot water inside the tank 51, sensors (not illustrated) including various temperature sensors necessary for controlling operation of the refrigeration circuit 32 and boiling up of the hot water of the hot water supply tank 12.

[0043] The circulating water piping 42 includes an outgoing pipe 61 that sends the circulating water heated in the water heat exchanger 11 to the coil 55 in the hot water supply tank 12, and a return pipe 62 that returns the circulating water whose temperature has dropped after heating the water supply in the tank 51 by the coil 55 from the hot water supply tank 12 to the water heat exchanger 11. The first pump 43, the backup heater 31, and the expansion tank 45 are provided in the middle of the outgoing pipe 61. The flow rate sensor 46 is provided in the middle of the return pipe 62.

[0044] The heat medium circulation circuit 41 includes an exterior circulation circuit 65 that circulates the circulating water to the outside device 21. The exterior circulation circuit 65 includes an exterior circulating water piping 66 that branches the circulating water from the circulating water piping 42 to the outside device 21 and returns the circulating water used in the outside device 21 to the circulating water piping 42, a three-way valve 67 that switches the circulating route of the circulating water to either the side of the hot water supply tank 12 or the side of the outside device 21, a second pump 68 that conveys the circulating water going to the indoor device 23, and a mixing valve 69 that mixes a part of the circulating water used by the indoor device 23 with the circulating water going to the indoor device 23.

[0045] The exterior circulating water piping 66 includes an exterior outgoing pipe 71 that branches the circulating water from the circulating water piping 42 to the outside device 21, and an exterior return pipe 72 that returns the circulating water used in the outside device 21 to the circulating water piping 42.

[0046] The heated circulating water used in the outside device 21 is sent to the outside device 21 through the exterior outgoing pipe 71 of the exterior circulation circuit 65 that branches from the outgoing pipe 61 of the heat medium circulation circuit 41 between the water heat exchanger 11 and the hot water supply tank 12. The exterior outgoing pipe 71 further branches into a first outgoing pipe 71a that sends circulating water to the radiator 22 and a second outgoing pipe 71b that sends circulating water to the indoor device 23.

[0047] The circulating water used in the outside device 21 is returned to the return pipe 62 of the heat medium circulation circuit 41 between the hot water supply tank 12 and the water heat exchanger 11 through the exterior return pipe 72 of the exterior circulation circuit 65. The exterior return pipe 72 joins a first return pipe 72a that returns circulating water from the radiator 22 and a second return pipe 72b that returns circulating water from the indoor device 23.

[0048] The three-way valve 67 joins the exterior return pipe 72 of the exterior circulating water piping 66 with the return pipe 62 of the heat medium circulation circuit 41. The three-way valve 67 connects the return side of the exterior return pipe 72 of the exterior circulating water piping 66 and the return side of the hot water supply tank 12 of the circulating water piping 42 to the inlet side of the circulating water of the water heat exchanger 11. The three-way valve 67 selectively switches either the circulating water flow from the hot water supply tank 12 to the water heat exchanger 11 or the circulating water flow from the outside device 21 to the water heat exchanger 11. The circulating route of the circulating water is set to either the hot water supply tank 12 side or the outside device 21 side by switching of the three-way valve 67.

[0049] The mixing valve 69 connects the upstream side of the second pump 68 of the second outgoing pipe 71b and the middle of the second return pipe 72b.

[0050] The mixing valve 69 controls the temperature of circulating water circulating through the indoor device 23 to satisfy the temperature requirements set for the indoor device 23 by varying the amount of mixing of the circulating water going to the indoor device 23 and the circulating water returning from the indoor device 23. Note that while the heat pump water heater 1 enables supply of hot water to two outside devices 21 (22 and 23) in the present embodiment, the number of outside devices 21 may be one. Moreover, the heat pump water heater 1 may be used exclusively for hot water supply without the ability to supply hot water to the outside device 21.

[0051] There is at least one remote controller 5. The remote controller 5 may include a remote controller provided in the hot water supply tank unit 3, for example, and a remote controller (not illustrated) installed on an indoor wall surface, for example.

[0052] As illustrated in Fig. 2, the remote controller 5 of the embodiment is provided in a front center portion of the hot water supply tank unit 3. The remote controller 5 is an input device into which a boiling up setting temperature of hot water in the hot water supply tank 12 can be input. Furthermore, the remote controller 5 can receive input of the setting temperature of circulating water to be circulated to the outside device 21. The remote controller 5 transmits the boiling up setting temperature of hot water in the hot water supply tank 12 and the setting temperature of circulating water to be circulated to the outside device 21 as a control signal to the control unit 6.

[0053] The control unit 6 includes a microprocessor (not illustrated), and a storage device (not illustrated) that stores various calculation programs executed by the microprocessor and parameters. The control unit 6 is an electrical circuit and is mounted on an electric circuit substrate (not illustrated). The control unit 6 reads various control programs from an auxiliary storage device into a main storage device, and executes the various control programs read into the main storage device in a central processing unit.

[0054] The control unit 6 performs operation control of the heat pump water heater 1, including operation of the refrigeration circuit 32 and operation of the first pump 43 of the heat medium circulation circuit 41, on the basis of control signals received from the remote controller 5 via wired or wireless communication lines and the output of the sensors. For example, the control unit 6 performs operation control of the heat pump water heater 1 so that the measured temperature of the temperature sensor is the boiling up setting temperature of hot water in the hot water supply tank 12.

[0055] The control unit 6 further performs switching control of the three-way valve 67 to switch the circulating route of the circulating water to one of the hot water supply tank 12 and the outside device 21, or alternately switch the circulating route of the circulating water between the hot water supply tank 12 and the outside device 21, and balances the supply of the circulating water to the outside device 21 with the boiling up of the hot water in the hot water supply tank 12. The remote controller 5 preferably includes a function of switching between these operational states.

[0056] As illustrated in Figs. 2 to 5 as well as Fig. 1, the hot water supply tank unit 3 according to the present embodiment includes a vertical rectangular housing 81, the hot water supply tank 12 accommodated on the lower side inside the housing 81, the water heat exchanger 11 accommodated above the hot water supply tank 12 inside the housing 81, a part of the refrigeration circuit 32 accommodated above the hot water supply tank 12 inside the housing 81 to circulate the refrigerant whose heat is exchanged by the water heat exchanger 11, and the heat medium circulation circuit 41 that is accommodated above the hot water supply tank 12 inside the housing 81 to circulate circulating water whose heat is exchanged by the water heat exchanger 11.

[0057] As illustrated in Figs. 4 and 5, the hot water supply tank unit 3 includes a drain pan 82 that is disposed between the water heat exchanger 11, a part of the refrigeration circuit 32, and the heat medium circulation circuit 41, and the hot water supply tank 12.

[0058] The housing 81 includes four support legs 83 provided at the four corners of the housing 81 to support the hot water supply tank unit 3 on the installation surface, a bottom plate 85 supported by the four support legs 83 and facing the installation surface of the hot water supply tank unit 3, and a frame 86 supported by the bottom plate 85 and rising upward. As illustrated in Figs. 2 and 3, the housing 81 also includes a top plate 87 facing the bottom plate 85, and four side plates 88 hung across the bottom plate 85 and the top plate 87. As illustrated in Figs. 4 and 5, the housing 81 further includes an electric circuit box fixing plate 89 between the hot water supply tank 12 and the side plate 88. The shape of the housing 81 as viewed from above with reference to the installation state of the hot water supply tank unit 3, that is, the planar shape of the housing 81, is a rectangle having four sides of the front surface, the back surface, the right side surface, and the left side surface. The planar shapes of the bottom plate 85 and the top plate 87 are rectangles. The top plate 87, the bottom plate 85, and the four side plates 88 are made of steel to maintain its strength. The thicknesses of the side plate 88, the top plate 87, and the bottom plate 85, which require strength, are thicker in that order.

[0059] Each support leg 83 protrudes downward from each corner of a bottom surface of the rectangular bottom plate 85. The four support legs 83 stand on the installation surface such as an indoor floor to support the hot water supply tank unit 3. Each support leg 83 preferably includes a mechanism whose height is adjustable in the up-down direction of the housing 81, such as a mechanism extendable and retractable in the up-down direction by a screw. By adjusting the height of each support leg 83, the grounding posture of the hot water supply tank unit 3 is easily adjusted. Thus, the hot water supply tank unit 3 can be easily installed with a center line C of the tank 51 standing vertically and the bottom plate 85 and the top plate 87 horizontal.

[0060] The bottom plate 85 covers a bottom surface of the housing 81. The bottom plate 85 supports the entire housing 81 to the installation surface via the support legs 83.

[0061] As illustrated in Figs. 4 and 5, the frame 86 includes a Rahmen structure in which a plurality of pillar members 91 and a plurality of beam members 92 are rigidly joined by fastening members such as screws (not illustrated). Each pillar member 91 is a so-called angle material having an L-shaped cross section that is uniform in the longitudinal direction. Each beam member 92 is a formed sheet metal having a C-shaped cross section that is uniform in the longitudinal direction. The frame 86 includes the four pillar members 91 rising substantially straight up from the corners of an upper surface of the rectangular bottom plate 85, and the plurality of beam members 92 hung substantially horizontally across adjacent pillar members 91.

[0062] The four pillar members 91 are a front right pillar member 91fr disposed at a front right edge portion of the housing 81, a front left pillar member 91fl disposed at a front left edge portion, a back right pillar member 91br disposed at a back right edge portion, and a back left pillar member 91bl disposed at a back left edge portion.

[0063] The plurality of beam members 92 include upper and lower two front beam members 92fu and 92fd hung across the two front pillar members 91fr and 91fl, upper and lower two back beam members 92bu and 92bd hung across the two back pillar members 91br and 91bl, upper and lower two right beam members 92ru and 92rd hung across the two right pillar members 91fr and 91br, and upper and lower two left beam members 92lu and 92ld hung across the two left pillar members 91fl and 91bl. The plurality of beam members 92 are disposed above the hot water supply tank 12 and the drain pan 82.

[0064] The upper right beam member 92ru is hung across a top portion of the front right pillar member 91fr and a top portion of the back right pillar member 91br. The upper left beam member 92lu is hung across a top portion of the front left pillar member 91fl and a top portion of the back left pillar member 91bl.

[0065] The lower right beam member 92rd is disposed below the upper right beam member 92ru, and the lower left beam member 92ld is disposed below the upper left beam member 92lu. The lower right beam member 92rd and the lower left beam member 92ld are disposed parallel to each other at substantially the same height with respect to the bottom surface of the housing 81.

[0066] The upper front beam member 92fu is disposed below the upper right beam member 92ru and upper left beam member 92lu and above the lower right beam member 92rd and lower left beam member 92ld.

[0067] The upper back beam member 92bu is hung across the top portion of the back right pillar member 91br and the top portion of the back left pillar member 91bl. The upper back beam member 92bu, the upper right beam member 92ru, and the upper left beam member 92lu are disposed parallel to each other at substantially the same height with respect to the bottom surface of the housing 81.

[0068] The lower front beam member 92fd and the lower back beam member 92bd are disposed below the lower right beam member 92rd and lower left beam member 92ld and are disposed parallel to each other at substantially the same height with respect to the bottom surface of the housing 81.

[0069] The top plate 87 covers a top surface of the housing 81. The top plate 87 includes a plurality of through holes 101 that allow the plurality of pipes 15, 16, 53, 56, 71a, 71b, 72a, and 72b to separately protrude to the outside from the inside of the housing 81. The plurality of through holes 101 are disposed in the vicinity of an edge portion of the top plate 87 defining a back surface 81b of the housing 81, and are aligned in the width direction of the housing 81. Each pipe includes a connection port 102 exposed to the outside of the housing 81. The connection ports 102 are couplers that are connectable to the crossover pipes 15 and 16 of the refrigeration circuit 32, or the water pipes 53, 56, 71a, 71b, 72a, and 72b to the outside of the hot water supply tank unit 3.

[0070] The four side plates 88 covering the side surfaces of the housing 81 are a front plate 88f covering the front surface of the housing 81, a back plate 88b covering the back surface of the housing 81, a right plate 88r covering the right side surface of the housing 81, and a left plate 88l covering the left side surface of the housing 81. Each side plate 88 is a flat panel made of sheet metal. The shape of each side plate 88 is a rectangle having its long side in the up-down direction of the hot water supply tank unit 3 and its short side in the horizontal direction thereof.

[0071] The top plate 87, the bottom plate 85, and the four side plates 88 are collectively referred to as external parts. The bottom plate 85 forms a bottom surface to be a reference plane of the hot water supply tank unit 3. The front, back, left, and right pillar members 91 are firmly fixed to this bottom plate 85 by fastening members. The beam members 92 are fixed to the front, back, left, and right pillar members 91 by fastening members. The side plates 88 are fixed to the front, back, left, and right pillar members 91 by fastening members. The top plate 87 is fixed to the side plates 88 by fastening members. The fastening member may be a screw, or may be a combination of a bolt and a nut. During assembly, the bottom plate 85 is fixed to the front, back, left, and right pillar members 91, the beam members 92 are fixed to the front, back, left, and right pillar members 91, the side plates 88 are fixed to the front, back, left, and right pillar members 91, and the top plate 87 is fixed to the side plates 88. The housing 81 can be broken down by going backwards in this order. Note that the top plate 87 may be fixed only to the front, back, left, and right pillar members 91 instead of the side plates 88. With this configuration, the side plates 88 can be easily removed from the front, back, left, and right pillar members 91 without removing the top plate 87.

[0072] When one or more fastening members fixing the side plate 88 are removed from the hot water supply tank unit 3, the side plate 88 can be removed from the hot water supply tank unit 3 and the state illustrated in Figs. 4 and 5 can be obtained. When the side plate 88 is removed from the hot water supply tank unit 3, the inspection and confirmation operation of the various devices in the hot water supply tank unit 3 can be carried out easily.

[0073] The electric circuit box fixing plate 89 is obtained by bending a part of a flat sheet metal plate member. The electric circuit box fixing plate 89 faces one of the four side plates 88, that is, the front plate 88f in the present embodiment. The electric circuit box fixing plate 89 is located between the hot water supply tank 12 and the front plate 88f. The electric circuit box fixing plate 89 is fixed to the front beam member 92fd and the two front pillar members 91fr and 91fl located on the left and right of the front beam member 92fd by fastening members such as screws. A front surface of the electric circuit box fixing plate 89 faces an inner surface of the front plate 88f. A lower end portion of the electric circuit box fixing plate 89 is fixed to the bottom plate 85 by fastening members. An upper end portion of a back surface of the electric circuit box fixing plate 89 faces the drain pan 82.

[0074] Here, a space above an upper surface of the drain pan 82 is referred to as a machine room 111. The electric circuit box fixing plate 89 partitions a space below the upper surface of the drain pan 82 inside the housing 81 into front and back two spaces. A space behind the electric circuit box fixing plate 89 is referred to as a tank room 112 in which the hot water supply tank 12 and the drain pan 82 are accommodated. A space in front of the electric circuit box fixing plate 89 is referred to as an electric room 113. The tank room 112 and the electric room 113 are below the machine room 111 and adjacent to each other in the front-rear direction of the housing 81 via the electric circuit box fixing plate 89. The electric room 113 is a space between the front plate 88f and the electric circuit box fixing plate 89, and the tank room 112 is a space between the electric circuit box fixing plate 89 and the back plate 88b. The tank room 112 is a space larger than the electric room 113.

[0075] The hot water supply tank 12 is mounted at the substantial center of the bottom plate 85. The tank 51 of the hot water supply tank 12 is a so-called cylindrical tank. The hot water supply tank 12 is installed with the center line C of the tank 51 standing in the up-down direction. In the stalled state of the hot water supply tank 12, an extending direction of the center line C of the tank 51 substantially coincides with the height direction of the hot water supply tank 12, the height direction of the housing 81, and the height direction of the hot water supply tank unit 3.

[0076] The tank 51 is fixed at the substantial center of the bottom plate 85 and stored in the hot water supply tank unit 3.

[0077] The tank 51 includes a lower mirror plate 121 disposed in the vicinity of the bottom plate 85, the upper mirror plate 122 covered with the drain pan 82, a cylindrical body portion 123 that connects the lower mirror plate 121 and the upper mirror plate 122, and a ring-shaped leg portion 125 that supports the lower mirror plate 121 to the bottom plate 85. The lower mirror plate 121 has a downwardly protruding dome shape, the upper mirror plate 122 has an upwardly protruding dome shape, and the body portion 123 is a cylinder having a substantially uniform diameter and extending in the up-down direction. The center line C of the tank 51 substantially coincides with the center line of the body portion 123. The lower mirror plate 121, the upper mirror plate 122, and the body portion 123 are made of stainless steel. The thickness of the lower mirror plate 121, the thickness of the upper mirror plate 122, and the thickness of the body portion 123 are substantially the same. The border between the body portion 123 and the lower mirror plate 121 and the border between the body portion 123 and the upper mirror plate 122 are both welded in an airtight manner.

[0078] A plane that is perpendicular to the center line C of the hot water supply tank 12 is substantially the horizontal plane in the installed state of the hot water supply tank 12. The cross-sectional shape of the lower mirror plate 121, the upper mirror plate 122, and the body portion 123 on this plane is substantially circular. The bottom plate 85 and the top plate 87 are substantially perpendicular to the center line C of the hot water supply tank 12, and the side plate 88 is substantially parallel to the center line C of the hot water supply tank 12.

[0079] In the height direction of the tank 51, the body portion 123 is longer than the lower mirror plate 121 and also longer than the upper mirror plate 122. The height dimension of the tank 51 is larger than the diameter dimension of the tank 51. In other words, the tank 51 is a vertical cylindrical tank.

[0080] The leg portion 125 is welded to an outer surface of the lower mirror plate 121 which is a bottom surface of the tank 51. The leg portion 125 is a circle having a smaller diameter than the maximum diameter of the lower mirror plate 121. The leg portion 125 is fixed to the bottom plate 85 via a plurality of angle materials (not illustrated) having an L-shaped cross section and a plurality of fastening members (not illustrated) such as bolts. The leg portion 125 may have a tongue piece corresponding to the angle material as one body. That is, the angle material may be omitted.

[0081] The water heat exchanger 11 is accommodated in the machine room 111. The water heat exchanger 11 is disposed in the vicinity of an inner surface of either the left or right side surface of the housing 81, that is, the left side surface in the present embodiment. The water heat exchanger 11 having a plate-shaped appearance is mounted so as to spread in the up-down direction and front-rear direction of the housing 81 along the inner surface of the left side surface of the housing 81. The water heat exchanger 11 is fixed to the upper left beam member 92lu and the lower left beam member 92ld by a plurality of fastening members such as bolts.

[0082] A part of the refrigeration circuit 32 accommodated in the machine room 111 is a part of the refrigerant piping 13 that is connected to the crossover pipes 15 and 16 to circulate the refrigerant to the water heat exchanger 11. The part of the refrigeration circuit 32 includes a passage in the water heat exchanger 11 through which the refrigerant circulates.

[0083] The heat medium circulation circuit 41 accommodated in the machine room 111 includes the first pump 43, the flow rate sensor 46, the expansion tank 45, and the circulating water piping 42 that connects these parts. The heat medium circulation circuit 41 accommodated in the machine room 111 also includes the exterior circulation circuit 65, that is, the three-way valve 67, the mixing valve 69, the second pump 68, and the exterior circulating water piping 66.

[0084] The backup heater 31 of the heat medium circulation circuit 41 is disposed in the electric room 113 below the drain pan 82. The backup heater 31 is located to the side of the hot water supply tank 12 in the height direction of the housing 81, is disposed on the right side of the electric room 113 adjacent to the front right corner of the housing 81, and faces the inner surface of the front plate 88f and an inner surface of the right plate 88r. The backup heater 31 is disposed between the hot water supply tank 12, which is circular in outer shape in plan view, and a corner of the housing 81, which has a rectangular interior space, avoiding the proximity between the hot water supply tank 12 and the side plate 88.

[0085] The electric circuit substrate on which the control unit 6 is mounted is accommodated in a rectangular electric circuit box 131. The electric circuit box 131 is accommodated in the electric room 113 located on the front side in the housing 81.

[0086] The electric circuit box 131 is a rectangular box body flat in the front-rear direction of the housing 81. The front of the electric circuit box 131 faces the inner surface of the front plate 88f, and the back of the electric circuit box 131 faces the front surface of the electric circuit box fixing plate 89. The electric circuit box 131 is made of sheet metal. The electric circuit box 131 includes a flange portion that is hooked to the beam member 92fd and fixed to the beam member 92fd by a fastening member such as a screw. By removing the fastening member and unhooking the flange portion, the electric circuit box 131 can be taken out of the hot water supply tank unit 3. In the case of removing the electric circuit box 131, since the flange portion is hooked to the beam member 92fd, the electric circuit box 131 does not fall even when the fastening member is removed. Thus, the removing operation of the electric circuit box 131 is facilitated. The electric circuit box 131 is wider than the backup heater 31 accommodated adjacent thereto in the electric room 113, and occupies most of an upper half portion of the electric room 113. The electric circuit box 131 can be opened and closed toward the front of the housing 81 to allow easy inspection, repair, or replacement operation of the internal electric circuit board without removing the electric circuit box 131 from the hot water supply tank unit 3.

[0087] Next, a structure of the drain pan 82 portion will be described in detail with reference to Figs. 6 to 8. The drain pan 82 is disposed below the plurality of beam members 92 of the frame 86.

[0088] The drain pan 82 of the hot water supply tank unit 3 according to the present embodiment is placed on and supported by the hot water supply tank 12. In the front-rear direction of the housing 81, the drain pan 82 has a small gap between itself and two adjacent pillar members 91 and the electric circuit box fixing plate 89. When an external force is applied to the drain pan 82, the drain pan 82 comes into contact with the electric circuit box fixing plate 89 or one of the pillar members 91 and is prevented from moving largely (shifting) in the front, back, left, or right direction of the housing 81.

[0089] Additionally, in the up-down direction of the housing 81, the drain pan 82 is mounted on the top portion of the tank 51 of the hot water supply tank 12 and covers the upper mirror plate 122 of the tank 51. The drain pan 82 is supported by the upper mirror plate 122 of the tank 51. A load acting on the drain pan 82 from top to bottom is transmitted through the drain pan 82 and supported by the hot water supply tank 12.

[0090] As illustrated in Fig. 8, the drain pan 82 is also a part of the heat insulation material 58 of the tank 51. The material of the drain pan 82 is either expanded polystyrene or expanded polyurethane foam, which has better heat insulation performance than expanded polystyrene. Note that a top surface of the drain pan 82 receiving the drainage has a surface treatment to prevent moisture from penetrating into the interior of the expanded polystyrene or expanded polyurethane foam. The drain pan 82 includes a curved inner bottom surface 82b1 that is in contact with the upwardly protruding dome-shaped upper mirror plate 122, which is the top portion of the tank 51, without any gaps, and an annular outer bottom surface 82b2 that is in contact with an annular upper surface of a middle heat insulation portion 132 without any gaps. Note that a porous material 58a filling the gap between the drain pan 82 and the middle heat insulation portion 132 may be interposed between the drain pan 82 and the middle heat insulation portion 132.

[0091] The upper surface of the drain pan 82 faces a lower surface of the top plate 87. The upper surface of the drain pan 82 corresponds to a bottom surface of the machine room 111.

[0092] As illustrated in Figs. 6 and 7, front, back, left, and right four edge portions 141 of the upper surface of the drain pan 82 protrude upward from a closed region on the inside thereof. Upper end surfaces of the four edge portions 141 are on substantially the same horizontal plane in an installed state of the hot water supply tank unit 3. The region surrounded and closed by the edge portions 141 of the upper surface of the drain pan 82 is a part where drainage is collected, and is referred to as a drainage receiving recess 142. The four edge portions 141 correspond to embankment around the drainage receiving recess 142 and prevent moisture accumulated in the drainage receiving recess 142 from overflowing from the drain pan 82.

[0093] The drain pan 82 receives water dripping from equipment including heat exchangers, pipes, and valves disposed in the machine room 111, such as the water heat exchanger 11, refrigerant piping 13, the circulating water piping 42, and the exterior circulating water piping 66 at the drainage receiving recess 142. The water dripping from the equipment is water that has condensed on the surface of the equipment or leaked from a circuit. Therefore, it is preferable that the drainage receiving recess 142 cover the entire area directly below the equipment, piping, and valves disposed in the machine room 111.

[0094] The drain pan 82 covering the top portion of the hot water supply tank 12 includes a plurality of pipe placement holes 143 that allow a plurality of pipes connected to the tank 51 to pass through separately. The plurality of pipes connected to the tank 51 are the water supply pipe 53, the hot water supply pipe 56, at least one of the outgoing pipe 61 and the circulating water introduction portion 55a of the coil 55, and at least one of the exterior return pipe 72 and the circulating water returning portion 55c of the coil 55. The pipe placement holes 143 are disposed in the drainage receiving recess 142. Note that the lower end of each pipe placement hole 143 is closed by the tank 51.

[0095] As can be seen from Fig. 7, the drain pan 82 is also a base for supporting the second pump 68. A sheet metal box disposed on the upper surface of the drain pan 82 to accommodate the first pump 43 and other equipment are fixed to either the beam member 92 or the pillar member 91. The drain pan 82 includes a plurality of protrusions 145 for maintaining a distance between equipment and drainage accumulated in the drainage receiving recess 142 to prevent contact between the equipment and drainage, and guiding the drainage dripping from the equipment to a low position of the drainage receiving recess 142. The plurality of protrusions 145 are disposed in the drainage receiving recess 142. The protruding height of the plurality of protrusions 145 may be higher or lower than the protruding height of the edge portion 141 of the drain pan 82. The plurality of protrusions 145 may be connected to a lower portion of the edge portion 141 of the drain pan 82, or may protrude from the drainage receiving recess 142 like an island.

[0096] The drain pan 82 also includes a drain hole 146 for discharging the drainage accumulated in the drainage receiving recess 142. The drain hole 146 penetrates a bottom portion of the drain pan 82. The drain hole 146 is preferably provided at the lowest part of the drainage receiving recess 142. The entire drainage receiving recess 142 is preferably inclined downward toward the drain hole 146. The lower end of the drain hole 146 is connected to a flexible drain pipe 147 (Fig. 7) that discharges water accumulated in the drain pan 82 to the outside of the hot water supply tank unit 3. As indicated by a two-point broken line in Fig. 3, the drain pipe 147 hangs down to the outside of the housing 81 through an opening 148 provided in the back plate 88b. The lower end (tip end) of the drain pipe 147 is preferably connectable to a discharge system provided at the installation location of the hot water supply tank unit 3.

[0097] When the drain hole 146 or drain pipe 147 becomes clogged with foreign matter, the drainage accumulates in the drainage receiving recess 142. When the amount of drainage accumulated in the drainage receiving recess 142 exceeds the capacity of the drainage receiving recess 142, the drainage overflows from the drain pan 82. Since the heat pump water heater 1 is generally installed indoors, if drainage overflowing from the drain pan 82 spills in the room, it may cause problems such as wetting the floor. Therefore, it is preferable that overflowed drainage flow down in the housing 81 and be received by the bottom plate 85.

[0098] However, if the flow down route of the drainage that flows down from the drain pan 82 to the bottom plate 85 is not fixed, the electric circuit box 131 below the drain pan 82 may get wet. When the electric circuit box 131 gets wet, the electric circuit inside the electric circuit box 131, that is, the control unit 6 gets wet and shorts out in the middle of the conduction path, causing the heat pump water heater 1 to stop working.

[0099] Against this background, as illustrated in Figs. 6 and 7, the drain pan 82 of the hot water supply tank unit 3 according to the present embodiment includes a plurality of bulging portions 151 protruding in the direction of the left and right side plates 88 so as to be in proximity to the side plates 88 except for on the front side where the electric circuit box 131 is attached, and a plurality of non-bulging portions 152 farther away from the side plates 88 than the bulging portions 151. The hot water supply tank unit 3 causes the water overflowing from the drain pan 82 to flow down in the housing 81 via an overflow path 153 which is a gap between the non-bulging portion 152 of the drain pan 82 and the side plate 88, and guides the water to the bottom plate 85. That is, the drain pan 82 includes an upstream overflow path 155 provided in the non-bulging portion 152 and connected to the overflow path 153 to guide the water accumulated in the drain pan 82 to the overflow path 153.

[0100] The plurality of bulging portions 151 are continuous with the edge portion 141 of the drain pan 82 and protrude in a direction away from the drainage receiving recess 142. The plurality of bulging portions 151 include a right bulging portion 151r provided on the right side surface of the drain pan 82, and a left bulging portion 151l provided on the left side surface of the drain pan 82. In the horizontal direction of the housing 81, the right bulging portion 151r is disposed in a center portion of the right side surface of the drain pan 82, and the left bulging portion 151l is disposed in a center portion of the left side surface of the drain pan 82. The right bulging portion 151r is in proximity to the inner surface of the right plate 88r, and the left bulging portion 151l is in proximity to an inner surface of the left plate 88l. Each bulging portion 151 including an end surface substantially parallel to the inner surface of the side plate 88 along the inner surface of the flat side plate 88. The dimension of the gap between the side plate 88 in proximity to the bulging portion 151 and the bulging portion 151 is preferably smaller than 10 millimeters, and may be about four millimeters, for example. The slight gap is left to eliminate noise caused by rubbing between the metal side plate 88 and the drain pan 82 which is a foam material, during expansion and contraction based on the difference in temperature expansion rates.

[0101] The non-bulging portion 152 is adjacent to the bulging portion 151 and is farther away from the inner surface of the side plate 88 than the bulging portion 151. The non-bulging portion 152 includes a front right non-bulging portion 152rf on the front side of the right side surface of the drain pan 82, a back right non-bulging portion 152rb on the back side of the right side surface of the drain pan 82, a front left non-bulging portion 152lf on the front side of the left side surface of the drain pan 82, and a back left non-bulging portion 152lb on the back side of the left side surface of the drain pan 82. The right non-bulging portions 152rf and 152rb face the inner surface of the right plate 88r, and the left non-bulging portions 152lf and 152lb face the inner surface of the left plate 88l. Each non-bulging portion 152 includes an end surface substantially parallel to the inner surface of the side plate 88 along the inner surface of the flat side plate 88. The dimension of the gap between the side plate 88 that the non-bulging portion 152 faces and the non-bulging portion 152 is preferably 10 millimeters or more, and may be about 12.5 millimeters, for example.

[0102] The plurality of bulging portions 151 and the plurality of non-bulging portions 152 are left and right side surfaces of the drain pan 82 facing the inner sides of the left and right side plates 88. The bulging portion 151 and the non-bulging portion 152 may be connected with a slope, or may be connected with one or a plurality of steps.

[0103] The gap between the side plate 88 facing the non-bulging portion 152 and the non-bulging portion 152 is the overflow path 153. That is, the overflow path 153 is disposed on the inside of the right side surface and the inside of the left side surface of the housing 81. The overflow path 153 includes a front right overflow path 153rf on the front inner side of the right side surface of the housing 81, a back right overflow path 153rb on the back inner side of the right side surface of the housing 81, a front left overflow path 153lf on the front inner side of the left side surface of the housing 81, and a back left overflow path 153lb on the back inner side of the left side surface of the housing 81.

[0104] The upstream overflow path 155 is a partial cutout of the edge portion 141 corresponding to the embankment of the drain pan 82. The upstream overflow path 155 guides moisture accumulated in the drainage receiving recess 142 reliably to the overflow path 153 by partially reducing the height of the embankment. There are preferably a plurality of upstream overflow paths 155, and at least one upstream overflow path 155 is preferably connected to each overflow path 153. The depths of the plurality of upstream overflow paths 155 may be the same or may be different. By setting a difference in the depths of the plurality of upstream overflow paths 155, it is possible to set a priority of the overflow paths 153 from which the moisture accumulated in the drainage receiving recess 142 flows out.

[0105] The back of the drain pan 82 is in proximity to the back plate 88b directly fixed to the two back pillar members 91br and 91bl. The gap between the back of the drain pan 82 and the inner surface of the back plate 88b is only the thickness of the back pillar member 91br and 91bl which are angle materials, such as about 2.5 millimeters. Such a gap between the back of the drain pan 82 and the inner surface of the back plate 88b does not function as the overflow path 153 due to the large pressure loss.

[0106] Note that the two right beam members 92ru and 92rd and the two left beam members 92lu and 92ld are directly fixed to the pillar members 91 with the C-shaped cross section facing the outside of the housing 81, and the right plate 88r and the left plate 88l are brought into contact with the open ends of the left and right beam members 92ru, 92rd, 921u, and 921d and fixed to the pillar members 91. That is, there is a gap between the right plate 88r and left plate 88l and the pillar member 91, the gap being a distance equal to the thickness of the beam member 92ru, 92rd, 921u, and 921d interposed between the right plate 88r and left plate 88l and the pillar member 91. In plan view, the bulging portion 151 of the drain pan 82 projects from the region surrounded by the pillar members 91 and enters the gap to be in proximity to the right plate 88r and the left plate 88l.

[0107] As illustrated in Fig. 6, a front surface of the drain pan 82 is in contact with the electric circuit box fixing plate 89 and separates the electric room 113 from the front plate 88f. The electric room 113 accommodates the electric circuit box 131.

[0108] The inner surface of the back plate 88b of the housing 81 is in direct contact with the pillar members 91 of the frame 86. Accordingly, the hot water supply tank unit 3 can be kept in a prone posture with the back side facing down. With this prone posture, there is only a slight possibility of the hot water supply tank unit 3 to fall down as compared to a case of erecting the hot water supply tank unit 3. Accordingly, the prone posture is also a suitable posture for transporting the hot water supply tank unit 3.

[0109] In a case where the drain hole 146 becomes clogged, the drain pan 82 according to the present embodiment lets the drainage accumulated in the drainage receiving recess 142 flow out through the plurality of overflow paths 153 before the amount of drainage accumulating in the drainage receiving recess 142 exceeds the capacity of the drainage receiving recess 142. The plurality of overflow paths 153 are the two overflow paths 153rf and 153rb facing the right plate 88r and the two overflow paths 1531f and 153lb facing the left plate 88l. The two overflow paths 153rf and 153rb located on the right side of the housing 81 are separated by the right bulging portion 151r of the drain pan 82, and the two overflow paths 1531f and 153lb located on the left side of the housing 81 are separated by the left bulging portion 151l of the drain pan 82. Therefore, the water flowing out of the drain pan 82 flows from the drain pan 82 to the bottom plate 85 along or down at least one of the front side of the inner surface of the right plate 88r, the back side of the inner surface of the right plate 88r, the front side of the inner surface of the left plate 88l, and the back side of the inner surface of the left plate 88l. These flow down routes of water flowing out of the drain pan 82 do not overlap the electric circuit box 131 in proximity to the front surface side of the housing 81. That is, the electric circuit box 131 is very unlikely to get wet from the water flowing out of the drain pan 82. Even if a little moisture attaches to the electric circuit box 131, there is hardly any possibility that the control unit 6 accommodated in the electric circuit box 131 will get wet.

[0110] Note that the electric circuit box 131 accommodating the control unit 6 only needs to be in proximity to any one of the plurality of side plates 88, and the side plate 88 is not limited to the front plate 88f. In this case, the overflow path 153 only needs to be disposed between the drain pan 82 and at least one of the other three side plates 88 of the plurality of side plates 88. That is, it is sufficient that the electric circuit box 131 and the overflow path 153 are disposed on the inner side of two different side plates 88 of the four side plates 88 of the housing 81.

[0111] As illustrated in Figs. 5, 6, 9, and 10, the bottom plate 85 of the hot water supply tank unit 3 according to the present embodiment includes a front edge planar portion 161 that defines a bottom surface of the electric room 113, a tank support base portion 162 that defines a bottom surface of the tank room 112 and includes a seat surface 162a on which the hot water supply tank 12 is mounted, and a flange 163 that is continuous with the four sides of the bottom plate 85 and extends upward to surround the front edge planar portion 161 and the tank support base portion 162.

[0112] The front edge planar portion 161 is connected to the front of the tank support base portion 162. The front edge planar portion 161 spreads over the entire width of the vicinity of the front edge of the bottom plate 85. The front edge planar portion 161 is substantially parallel to the top plate 87 of the housing 81.

[0113] The front edge planar portion 161 includes a left and right pair of handle openings 165 for inserting a person's fingers when transporting the hot water supply tank unit 3 by hand. The left and right handle openings 165 are placed at intervals that make it easy to insert the left and right fingers of the same person when transporting by hand. A resin handle 166 is provided in the handle opening 165. The handle 166 includes a claw (not illustrated) that can be hooked to an edge of the handle opening 165, and a support piece for elastically supporting the claw. The handle 166 is fixed to the bottom plate 85 by bending the support piece and hooking the claw to the handle opening 165. A person carrying the hot water supply tank unit 3 can easily lift the hot water supply tank unit 3 by inserting his / her fingers into the handle openings 165 from the outside to the inside of the hot water supply tank unit 3 and then hooking the fingers on the handles 166 while tilting the hot water supply tank unit 3 backward using the pair of support legs 83 near the corners of the bottom plate 85 and back plate 88b as fulcrums. On the top plate 87 side of the hot water supply tank unit 3, the corners of the top plate 87 and the back plate 88b are gripped as appropriate. When lowering the hot water supply tank unit 3 after transportation, the hot water supply tank unit 3 easily returns to the upright posture by grounding the pair of support legs 83 near the corners of the bottom plate 85 and back plate 88b.

[0114] The tank support base portion 162 includes, in the height direction of the housing 81, a lowest first flat portion 171, a second flat portion 172 as the seat surface 162a of the hot water supply tank 12, and two third flat portions 173 provided at each of the two back corners of the bottom plate 85.

[0115] The shape of the second flat portion 172 is substantially circular to facilitate placement of the annular leg portion 125 of the hot water supply tank 12, and includes a string portion 162b substantially parallel to the front edge planar portion 161 in proximity to the front edge planar portion 161.

[0116] A plurality of fastening members 127 for fixing the hot water supply tank 12 are provided in the second flat portion 172. The plurality of fastening members 127 are arranged at equal intervals on a concentric circle of the circular second flat portion 172.

[0117] The second flat portion 172 includes a recess 175 located in the center of the tank support base portion 162 so as not to interfere with a top portion (lowest portion) of the dome-shaped lower mirror plate 121 of the hot water supply tank 12. The height position of a bottom surface of the recess 175 is set at the same height position as the first flat portion 171. This improves the sheet metal workability of the bottom plate 85. If interference between the lower mirror plate 121 and the bottom plate 85 is avoided, the recess 175 may be omitted.

[0118] The second flat portion 172 also includes two bridge portions 176 that reach the left and right flanges 163. A right bridge portion 176r reaches a right flange 163r, and a left bridge portion 176l reaches a left flange 163l. Each bridge portion 176 passes through the center of the substantially circular second flat portion 172 and extends in a direction perpendicular to the left and right flanges 163r and 163l. The two bridge portions 176 may be omitted.

[0119] The two third flat portions 173 are a right third flat portion 173r disposed at the right back corner of the bottom plate 85 and connecting the right flange 163r to a back flange 163b, and a left side third flat portion 173l located at the left back corner of the bottom plate 85 and connecting the left flange 163l to the back flange 163b. Each third flat portion 173 includes a rounded corner 173a on the opposite corner where the flange 163 bends at a right angle. The rounded corner 173a is closest to the second flat portion 172 in the third flat portion 173.

[0120] In the height direction of the housing 81, the first flat portion 171 is disposed lower than the front edge planar portion 161, the second flat portion 172, and the third flat portion 173. The first flat portion 171 located below the front edge planar portion 161, the second flat portion 172, and the third flat portion 173 causes the bottom plate 85 to function as a second drain pan that receives drainage that flows down to the bottom plate 85.

[0121] The first flat portion 171 is divided into a front drainage receiving recess 177f and a back drainage receiving recess 177b with the second flat portion 172 in between. The front drainage receiving recess 177f is surrounded by the back edge of the front edge planar portion 161, the front edges of the left and right flanges 163, the front edges of the left and right bridge portions 176, left and right arcs of the second flat portion 172, and the string portion 162b of the second flat portion 172. The back drainage receiving recess 177b is surrounded by a back arc of the second flat portion 172, the back edges of the left and right bridge portions 176, the backs of the left and right flanges 163, the edges of the left and right third flat portions 173, and the back flange 163b. The first flat portion 171 may radiate into the center of the circular portion of the second flat portion 172 and may be connected to the central recess 175 of the second flat portion 172. By connecting the first flat portion 171 and the central recess 175 of the second flat portion 172, the accumulation amount of drainage in the bottom plate 85 can be increased.

[0122] The upper ends of the flanges 163 are aligned at substantially the same height in the height direction of the housing 81.

[0123] Each support leg 83 of the hot water supply tank unit 3 is disposed at each corner of the bottom plate 85 in the third flat portion 173 of the tank support base portion 162 or the front edge planar portion 161. That is, the first flat portion 171, which includes the front drainage receiving recess 177f and the back drainage receiving recess 177b, is disposed below the plate portions (third flat portion 173 and front edge planar portion 161) where the support leg 83 supports the bottom plate 85.

[0124] The bottom plate 85 including the flange 163 surrounding it and a plurality of plate portions (front edge planar portion 161, first flat portion 171, second flat portion 172, and third flat portion 173) disposed at different heights in a portion corresponding to the inner web of this flange 163 functions as a second drain pan and has high rigidity as a support plate for supporting the hot water supply tank 12. The high rigidity is thought to be due to the of the third flat portion 173 coupling the end portions of the flanges 163. The bridge portion 176 coupling the first flat portion 171 to a center portion of the flange 163 further improves the rigidity of the bottom plate 85.

[0125] The handle 166 provided in the front edge planar portion 161 of the bottom plate 85 is covered with a rectangular handle cover 181 provided in the housing 81. The handle cover 181 is made of metal similar to the bottom plate 85, the top plate 87, and the side plate 88 which are external parts of the housing 81, and is a fabricated sheet metal product similar to the electric circuit box 131. The handle cover 181 includes a plurality of outer flanges 182 provided at the lower ends of left and right side surfaces. The outer flange 182 is bent toward the outside of the handle cover 181 from the lower end of each of the left and right side surfaces of the handle cover 181.

[0126] The front edge planar portion 161 includes left and right flange holders 183 into which rear end portions of the left and right outer flanges 182 of the handle cover 181 can be inserted separately. The flange holder 183 is a part where the metal sheet bottom plate 85 is cut and the vicinity of the cut is depressed toward the inside of the housing 81 (upper side of bottom plate 85), and is formed by cutting and bending the sheet metal bottom plate 85.

[0127] Each flange holder 183 has a triangular shape with a first side closest to and aligned with the tank support base portion 162, a second side intersecting the first side at a right angle and farthest from the other opposite flange holder 183, and a third side connecting the first and second sides and sloping toward the other flange holder 183 toward the tank support base portion 162. The left and right second sides are the same distance apart as the left and right outer flanges 182 of the handle cover 181. Therefore, when the rear end portion of the outer flange 182 of the handle cover 181 is inserted into the flange holder 183, the handle cover 181 reaches the first side while being guided by the second side, and the attachment position of the handle cover 181 to the bottom plate 85 is determined.

[0128] The top surface of the housing 81 of the hot water supply tank unit 3 is covered with the top plate 87, and the front surface, the back surface, the right side surface, and the left side surface are covered with the side plates 88 made of sheet metal. Meanwhile, the bottom plate 85 covering the bottom surface of the housing 81 exposes the handle 166 made of resin and flammable to the exterior of the housing 81 through the handle opening 165. If there is a fire around the hot water supply tank unit 3, the fire may melt or burn the flammable handle 166 and allow flames to enter the housing 81. Therefore, the hot water supply tank unit 3 according to the present embodiment surrounds the handle opening 165 and the handle 166 with a sheet metal handle cover 181 to prevent flames from entering the housing 81.

[0129] A front surface of the handle cover 181 includes two fastening members 185 for fixing the handle cover 181 to the handle 166, such as holes (not illustrated) through which screws are inserted. The two fastening members 185 are fastened to the handle 166 from the outside of the handle cover 181. The handle cover 181 is fixed to the housing 81 by the fastening member 185 fastened to the handle 166 and the flange holder 183 of the front edge planar portion 161. That is, only the two fastening members 185 are needed to assemble the handle cover 181 and the housing 81, reducing the number of parts required for installation compared to simply fastening the handle cover 181 to the housing 81 with only fastening members.

[0130] A top surface of the handle cover 181 is preferably parallel to the front edge planar portion 161 of the bottom plate 85. The top surface of the handle cover 181 is close to the support leg 83. Therefore, when installing the hot water supply tank unit 3, by placing a level on the top surface of the handle cover 181 and extending and retracting the support leg 83 while checking the level, the horizontal plane of the hot water supply tank unit 3 (plane perpendicular to center line C of tank 51) can be easily made parallel to the horizontal plane of the installation site to adjust the installation posture of the hot water supply tank unit 3.

[0131] As described above, the hot water supply tank unit 3 and the heat pump water heater 1 according to the present embodiments guide water overflowing from the drain pan 82 via the overflow path 153, which is the gap between the non-bulging portion 152 of the drain pan 82 and the side plate 88, to the lower side inside the housing 81. Therefore, even if drainage overflows from the drain pan 82, the hot water supply tank unit 3 and the heat pump water heater 1 define a route for the drainage to flow down to prevent drainage from wetting electric circuits that should not be wetted.

[0132] The hot water supply tank unit 3 and the heat pump water heater 1 according to the present embodiments include the control unit 6 as an electric circuit accommodated below the drain pan 82 in the housing 81 and in proximity to any one of the plurality of side plates 88, and the overflow path 153 disposed on at least one of the other three side plates 88 of the plurality of side plates 88. Therefore, the hot water supply tank unit 3 and the heat pump water heater 1 prevent the drainage flowing down from the drain pan 82 from wetting the control unit 6, even if the control unit 6 is disposed below the drain pan 82. Any one of the plurality of side plates 88 is, for example, the front plate 88f, where the control unit 6 is disposed on the front surface side of the housing 81, the other three side plates 88 are the back plate 88b, the right plate 88r, and the left plate 88l, and the overflow path 153 only needs to be disposed on at least one of the back surface side, the right side surface side, and the left side surface side of the housing 81.

[0133] Furthermore, the hot water supply tank unit 3 and the heat pump water heater 1 according to the present embodiments include the upstream overflow path 155 that is provided in the non-bulging portion 152 and leads to the overflow path 153, and guides water collected in the drain pan 82 to the overflow path 153. Therefore, the hot water supply tank unit 3 and the heat pump water heater 1 can reliably cause the drainage accumulated in the drain pan 82 to flow out to the overflow path 153 even if the drainage overflows from the drain pan 82.

[0134] Hence, according to the hot water supply tank unit 3 and the heat pump water heater 1 including this hot water supply tank unit 3 of the present embodiments, it is possible to prevent water from wetting the control unit 6 that is the electric circuit disposed below a drain pan even if the drain hole 146 of the drain pan 82 becomes clogged and the drain pan 82 overflows.

[0135] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.REFERENCE SIGNS LIST

[0136] 1... heat pump water heater, 2... outdoor unit, 3... hot water supply tank unit, 5... remote controller, 6... control unit, 11... water heat exchanger, 12... hot water supply tank, 13... refrigerant piping, 15, 16... crossover pipe, 21... outside device, 21... outside device, 22... radiator, 22... radiator, 23... indoor device, 31... backup heater, 32... refrigeration circuit, 35... compressor, 36... air heat exchanger, 37... expansion valve, 38... four-way valve, 39... accumulator, 41... heat medium circulation circuit, 42... circulating water piping, 43... first pump, 45... expansion tank, 46... flow rate sensor, 51... tank, 52... outlet, 53... water pipe, 55... coil, 56... hot water pipe, 58... insulation material, 55a... circulating water introduction portion, 55b... spiral portion, 55c... circulating water returning portion, 61... outgoing pipe, 62... return pipe, 65... exterior circulation circuit, 66... exterior circulating water piping, 67... three-way valve, 68... second pump, 69... mixing valve, 71... exterior outgoing pipe, 71a... first outgoing pipe, 71b... second outgoing pipe, 72... exterior return pipe, 72a... first return pipe, 72b... second return pipe, 81... housing, 82... drain pan, 82b... inner bottom surface, 82b... outer bottom surface, 83... support leg, 85... bottom plate, 86... frame, 87... top plate, 88... side plate, 88f... front plate, 88b... back plate, 88r... right plate, 881... left plate, 89...electric circuit box fixing plate, 91... pillar member, 91fr... front right pillar member, 91fl... front left pillar member, 91br... back right pillar member, 91bl... back left pillar member, 92... beam member, 92fu... front upper beam member, 92fd... front lower beam member, 92bu... back upper beam member, 92bd... back lower beam member, 92ru... right upper beam member, 92rd... right lower beam member, 921u... left upper beam member, 921d... left lower beam member, 101... through hole, 102... connection port, 111... machine room, 112... tank room, 113... electric room, 121... lower mirror plate, 122... upper mirror plate, 123... body portion, 125... leg portion, 127... fastening member, 131... electric circuit box, 132... body portion insulation portion, 141... edge, 142... drainage receiving recess, 143... pipe placement hole, 145... protrusion, 146... drain hole, 147... drain pipe, 148... opening, 151... bulging portion, 151r... right bulging portion, 1511... left bulging portion, 152... non-bulging portion, 152rf... front right non-bulging portion, 152rb... back right non-bulging portion, 152lf... front left non-bulging portion, 152lb... back left non-bulging portion, 153... overflow path, 153rf... front right overflow path, 153rb... back right overflow path, 1531f... front left overflow path, 153lb... back left overflow path, 155... upstream overflow path, 161... front edge planar portion, 162... tank support base portion, 162a... seat surface, 162b... string portion, 163... flange, 163r... right flange, 1631... left flange, 163b... back flange, 165... handle opening, 166... handle, 171... first flat portion, 172... second flat portion, 173... third flat portion, 173a... rounded corner, 173r... right third flat portion, 1731... left third flat portion, 175... recess, 176... bridge portion, 176r... right bridge portion, 1761... left bridge portion, 177f... front drainage receiving recess, 177b... back drainage receiving recess, 181... handle cover, 182... outer flange, 183... flange holder, 185... fastening member.

Claims

1. A hot water supply tank unit comprising: a housing including a bottom plate, a frame including a plurality of pillar members rising from the bottom plate, and a plurality of side plates hung across the adjacent pillar members; a hot water supply tank mounted on the bottom plate and accommodated in a lower side inside the housing; a water circuit accommodated above the hot water supply tank inside the housing and through which water flows; a drain pan disposed between the water circuit and the hot water supply tank and supported by the frame and the hot water supply tank; and an electric circuit accommodated below the drain pan inside the housing and in proximity to any one of the plurality of side plates, wherein the drain pan includes a bulging portion in proximity to at least one of other side plates of the plurality of side plates, and a non-bulging portion farther from the at least one other side plate than the bulging portion, and water overflowing from the drain pan is guided to the lower side inside the housing via an overflow path which is a gap between the non-bulging portion of the drain pan and the side plate.

2. The hot water supply tank unit according to claim 1, wherein the water circuit includes a water heat exchanger that exchanges heat between a refrigerant and the water, and a circulation circuit that circulates the water whose heat is exchanged by the water heat exchanger.

3. The hot water supply tank unit according to claim 1 or 2 further comprising a refrigeration circuit that is disposed directly above the drain pan and circulates the refrigerant whose heat is exchanged by the water heat exchanger.

4. The hot water supply tank unit according to any one of claims 1 to 3, wherein the drain pan is a formed product of a foaming material, and a gap is formed between the bulging portion and the side plate.

5. The hot water supply tank unit according to any one of claims 1 to 4, wherein the electric circuit is disposed on the front surface, and the overflow path is disposed on at least one of the back surface, the right side surface, and the left side surface.

6. The hot water supply tank unit according to any one of claims 1 to 5, wherein the drain pan includes an upstream overflow path that is provided in the non-bulging portion and continuous with the overflow path, and guides water collected in the drain pan to the overflow path.

7. The hot water supply tank unit according to any one of claims 1 to 6, wherein the bottom plate includes a handle opening, and the hot water supply tank unit further comprises a resin handle disposed in the housing and provided in the handle opening, a metal handle cover disposed in the housing and covering the handle, and a fastening member that fixes the handle cover to the handle.

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