GB2533069A

GB2533069A - Heat pump water heater

Info

Publication number: GB2533069A
Application number: GB1604144.4A
Authority: GB
Inventors: Kato Yasuaki
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2013-09-27
Filing date: 2013-09-27
Publication date: 2016-06-08
Anticipated expiration: 2033-09-27
Also published as: CN105579780A; CN105579780B; JPWO2015045114A1; GB2533069B; WO2015045114A1; JP6112212B2; GB201604144D0

Abstract

A heat pump water heater (1) comprises: an L-shaped air heat exchanger (5) that comprises a rear face air heat exchanger (5a) and a side face air heat exchanger (5b); a cooler box (14) that is disposed on a bottom face panel (9a) of a case (9) and that faces the rear face air heat exchanger (5a) and the side face air heat exchanger (5b) via a gap; and a blower (7) that has a propeller fan (15) disposed above the cooler box (14) and a bell mouth (18) disposed on the outside of the propeller fan (15) in the radial direction. A shield plate (21) is provided extending from the top face of the cooler box (14) toward the bell mouth. The shield plate (21) extends in a direction along the back face and is provided with a gap with the peripheral face of the bell mouth (18).

Description

Title of Invention

HEAT PUMP WATER HEATER

Technical Field [0001]

The present invention relates to a heat pump water heater.

Background Art

[0002] Heat pump water heaters that heat water using a refrigeration cycle (heat pump cycle) are widely used. Conventional heat pump water heaters typically have a configuration in which a cooler box (device housing box) with a water-refrigerant heat exchanger housed therein is arranged in front of an air heat exchanger, which is a fin tube heat exchanger, disposed on the rear side of a board of a housing and a propeller fan-type air blower that lets air through the air heat exchanger is arranged on the cooler box (see, for example, Patent Literature 1). A clearance that allows air to flow therethrough is provided between the air heat exchanger and the cooler box. Upon rotation of a propeller fan positioned in front of the air heat exchanger, external air is drawn into the housing through the air heat exchanger and discharged to the outside from a fan grill on the front surface of the housing.

[0003] -2 -In heat pump water heaters, the air heat exchanger corresponds to an evaporator in a refrigeration cycle and the water-refrigerant heat exchanger corresponds to a condenser, respectively, and in the water-refrigerant heat exchanger, heat is transferred from a refrigerant to water to provide hot water. In order to enhance energy saving performance while suppressing manufacturing costs without increase in size of the housing, it is effective to increase a volume of air passing through the air heat exchanger.

Citation List Patent Literature [0004] Patent Literature 1: Japanese Patent Laid-Open No. 2013-53776

Summary of Invention

Technical Problem [0005] In heat pump water heaters such as stated above, aerodynamic rotation sound generated as a result of rotation of a propeller fan of an air blower may be noise. According to the present inventors' studies, a main cause of such sound is as follows In a flow of air inside a heat pump water heater, air flowed in from a part of an air heat exchanger, the part facing a back surface of a cooler box, flows upward along the back surface of the cooler box and flows away from a corner between the back surface and an upper surface of the cooler box into the inner peripheral side of a propeller fan. As a result, in the vicinity of the upper surface of the cooler box, an amount of air flowing into the outer peripheral side of the propeller fan is small while an amount of air flowing into -3 -the inner peripheral side is large In other words, as viewed from the perspective of the rotating blades, when each of the blades passes above the cooler box, the air inflow is small on the outer peripheral side of the propeller fan (vector in a rotation axis direction is small) and the air inflow is larger on the inner peripheral side (vector in the rotation axis direction is large) compared to areas preceding and following the area above the cooler box Such inflow state variation causes variation in pressure on the surface of the blade, resulting in generation of noise from the blades according to the period of each blade. As stated above, in a heat pump water heater having the aforementioned structure, a flow speed distribution of air flowing into the air blower is likely to be nonuniform and therefore unpleasant aerodynamic rotation sound is likely to be generated by the air blower.

[0006] In the heat pump water heater disclosed in Patent Literature 1, in order to guide an airflow running upward along a back surface of a cooler box during operation of an air blower in a direction toward an outer peripheral region of a propeller of a propeller fan, a guide plate is provided between parts of a motor support that fixes a fan motor.

However, with such configuration, it is impossible to guide an airflow flowing into from a part of the air heat exchanger, the part facing a side surface of the cooler box, and running upward along the side surface of the cooler box. The airflow running upward along the side surface of the cooler box then runs toward the back surface along an upper surface of the cooler box and merges with the aforementioned rising airflow running along the back surface, and flows into the inner peripheral side of the propeller fan. Therefore, for example, if the aforementioned guide plate is extended in a transverse direction, some effect is exerted in terms of equalization of flow speed distribution of air -4 -flowing into the air blower however, the problem of energy efficiency decreases attributable to ncrease n air blowing load arises As stated above, the conventional heat pump water heater stated above still leaves room for mprovement in equalizing a flow distribution of air flowing into an air blower and thereby reducing aerodynamic rotation sound while suppressing energy efficiency decrease.

[0007] The present invention has been made in order to solve the aforementioned problems, and an object of the present invention is to provide a heat pump water heater capable of reducing aerodynamic rotation sound from an air blower while suppressing energy efficiency decrease.

Solution to Problem [0008] A heat pump water heater according to the present inventionincludes: a back air heat exchanger installed along a back surface inside a housing a side air heat exchanger installed along a side surface inside the housing; a device housing box installed on a bottom plate of the housing, the device housing box facing the back air heat exchanger and the side air heat exchanger across respective clearances; an air blower including a propeller fan arranged above the device housing box and a bellmouth installed on an outer side in a radial direction of the propeller fan, the air blower blowing air so that external air flows in through the back air heat exchanger and the side air heat exchanger; and a shield plate provided so as to be erected from an upper surface of the device housing box toward the bellmouth. -5 -

Advantageous Effects of Invention [0009] According to the present invention, a shield plate provided so as to be erected from an upper surface of a device housing box toward a bellmouth holds back air flowing from the front side to the back side of the bellmouth through a side air heat exchanger, whereby flow amounts (flow speeds) of air flowing into an outer peripheral part and an inner peripheral part of a propeller fan are equalized Consequently, a heat pump water heater capable of reducing aerodynamic rotation sound from an air blower while suppressing energy efficiency decrease can be provided.

Brief Description of Drawings

[0010] Figure 1 is a schematic diagram of a refrigerant circuit included in a heat pump water heater according to Embodiment 1 of the present invention.

Figure 2 is a front view of an outer appearance of the heat pump water heater according to Embodiment 1 of the present invention.

Figure 3 is a perspective view of an outer appearance on the front side of the heat pump water heater according to Embodiment 1 of the present invention.

Figure 4 is a perspective view of an outer appearance on the back side of the heat pump water heater according to Embodiment 1 of the present invention.

Figure 5 is a cross-sectional view of the heat pump water heater along A-A in Figure 2.

Figure 6 is a cross-sectional view of the heat pump water heater along B-B in Figure 2. -6 -

Figure 7 is a perspective diagram illustrating a propeller fan and a fan motor in the heat pump water heater according to Embodiment 1 of the present invention, Figure 8 is a diagram of the inside of the heat pump water heater according to Embodiment 1 of the present invention as viewed from the back side.

Figure 9 is a cross-sectional view of the heat pump water heater along C-C in Figure 8 Figure 1 Oisadiagram of the inside of the heat pump water heater according to Embodiment 1 of the present invention as viewed from the back side.

Description of Embodiment

[0011] An embodiment of the present invention will be described below with reference to the drawings Components that are common to the drawings are provided with a same reference numeral and overlapping description thereof will be omitted.

[0012] Embodiment 1 Figure 1 is a schematic diagram of a refrigerant circuit included in a heat pump water heater 1 according to Embodiment 1 of the present invention. As illustrated in Figure I, the refrigerant circuit included in the heat pump water heater I according to the present embodiment is configured by sequentially connecting a compressor 2, a water-refrigerant heat exchanger 3, an expansion valve 4 and an air heat exchanger 5 via refrigerant pipings 6a to 6d. Also, the heat pump water heater 1 includes an air blower 7 for letting air through the air heat exchanger 5.

[0013] -7 -Figure 2 is a front view of an outer appearance of the heat pump water heater 1 according to Embodiment 1 of the present invention Figure 3 is a perspective view of an outer appearance on the front side of the heat pump water heater 1 according to Embodiment 1 of the present invention Figure 4 is a perspective view of an outer appearance on the back side of the heat pump water heater I. Figure 5 is a cross-sectional view of the heat pump water heater 1 along A-A in Figure 2. Figure 6 is a cross-sectional view of the heat pump water heater 1 along B-B in Figure 2 [0014] As illustrated in Figures 2 to 6, the heat pump water heater 1 according to the present embodiment includes a housing 9 having a rough cuboidal shape. The housing 9 is configured by attaching a front panel 9b, a side panel 9c, a side panel 9d and a back panel 9e to a bottom panel 9a and covering top surfaces of these panels by means of a top panel 911 As illustrated in Figure 2, in the front panel 9b, a round opening 19 for discharging air blown from the air blower 7 covered by a bellmouth 18 is provided, and a net-like fan grill 10 is provided so as to cover the round opening 19. In Figure 2, for illustration of the air blower?, illustration of the fan grill 10 is partially omitted. As illustrated in Figure 4, a large opening portion is provided in each of the side panel 9d and the back panel 9e, and the opening portions are provided with an air heat exchanger 5. The air heat exchanger 5 has a rough L shape and includes a back air heat exchanger 5a arranged on the inner side of the back panel 9e and a side air heat exchanger 5b arranged on the inner side of the side panel 9d. Here, in the air heat exchanger 5, the back air heat exchanger 5a and the side air heat exchanger 5b may be integrated in an L shape or may be separated from each other.

[0015] -8 -On the bottom panel 9a, a separator 11 is provided in an erected manner. As illustrated in Figure 5, the inside of the housing 9 is divided into a machinery chamber 12 and an air passage chamber 13 by the separator 11. In the machinery chamber 12, e.g., the compressor 2 and the expansion valve 4 are arranged, and in the air passage chamber 13, e.g., a cooler box (device housing box) 14 that houses the water-refrigerant heat exchanger 3, the air heat exchanger 5 and the air blower 7 are arranged.

[0016] The air heat exchanger 5 having a rough L shape is arranged on the bottom panel 9a in such a manner that the back air heat exchanger 5a extends along a back surface of the housing 9 and the side air heat exchanger 5b extends along one side surface of the housing 9. Also, as illustrated in Figure 6, on the bottom panel 9a, the cooler box 14 is arranged with respective clearances 20a and 20b between the back air heat exchanger 5a and the side air heat exchanger 5b and the cooler box 14. Above the cooler box 14, the air blower 7 is arranged. Such configuration enables inclusion of a larger air heat exchanger 5 in the housing 9 having a limited size and also enables letting a large amount of air through the air heat exchanger 5 to enhance heat exchange processing performance of the air heat exchanger 5 and thereby enhance the heat pump cycle efficiency.

[0017] The air blower 7 includes a propeller fan IS including a plurality of blades (vanes), a bellmouth 18 arranged so as to cover the outer side in a radial direction of the propeller fan 15, and a fan motor 16, which serves as a motor that drives the propeller fan 15 to rotate. The inlet side and the outlet side of the bellmouth 18 expand outward in a radial direction, and an inlet-side end 18a is positioned on the outer side in the radial direction relative to a minimum inner diameter portion 18b. The fan motor 16 is fixed to a motor -9 -support 17. The motor support 17 includes a pair of leg portions, and a lower end portion of each of the leg portions is fixed to an upper surface 14c of the cooler box 14 A center line of rotation of the propeller fan 15 is arranged substantially horizontally and substantially perpendicular to the back air heat exchanger 5a. A radius of the propeller fan 15 is slightly smaller than a distance from the center line of rotation of the propeller fan 15 to the upper surface 14c of the cooler box 14. A tip of each blade of the rotating propeller fan 15 passes by the vicinity of the upper surface 14c of the cooler box 14. [0018] Here, names of parts of the propeller fan 15 will be described. Figure 7 is a perspective diagram illustrating the propeller fan 15 and the fan motor 16 of the heat pump water heater 1. As illustrated in Figure 7, a surface of each of the blades of the propeller fan 15, the surface facing in a direction of rotation of the blades, is referred to as a pressure side 15a, and a surface on the opposite side of the pressure side 15a is referred to as a suction side 15b. Also, an edge of each of the blades, the edge facing in the direction of rotation, is referred to as a front edge 15c.

[0019] Figure 8 is a diagram of the inside of the heat pump water heater 1 as viewed from the back side. In Figure 8, a view seen through the back air heat exchanger 5a and the side panel 9d is illustrated. Also, in Figure 8, a position of the side air heat exchanger 5b is indicated by dashed lines. Figure 9 is a cross-sectional view of the heat pump water heater 1 along C-C in Figure 8 and is an enlarged view of a part on the lower side relative to the center line of rotation of the propeller fan 15. As illustrated in Figure 9, a back surface 14a (facing surface) of the cooler box 14 faces a lower region (partial region on the lower side) of the back air heat exchanger 5a across the clearance 20a. Also, as -10 -illustrated in Figure 8, a side surface 14b of the cooler box 14 faces a lower region (partial region on the lower side) of the side air heat exchanger 5b across the clearance 20b.

[0020] As illustrated in Figures 8 and 9, on the upper surface 14c of the cooler box 14, shield plates 21a and 21b (hereinafter referred simply to as "shield plates 21" unless these plates are specifically distinguished from each other) are provided along the back air heat exchanger 5a (that is, along a longitudinal direction (transverse direction) of the cooler box 14). The shield plates 21 are intended to prevent interference between an rising airflow flowing into from the back air heat exchanger 5a facing the back surface 14a of the cooler box 14 and passing through the clearance 20a between the back air heat exchanger 5a and the cooler box 14 and an airflow flowing into from the side air heat exchanger 5b during operation of the air blower 7. The shield plate 21a is provided on a part of the upper surface 14c on the side air heat exchanger 5b side relative to the center of rotation of the propeller fan 15, and the shield plate 21b is provided on a part of the upper surface 14c on the machinery chamber 12 side relative to the center of rotation of the propeller fan 15. A height of each of the shield plates 21a and 21b is set so as to be higher than the inlet-side end 18a of the bellmouth 18 and provide a predetermined clearance between the relevant shield plate and an outer peripheral surface of the bellmouth 18 [0021] Next, with reference to Figures 1 and 5, operation of the heat pump water heater 1 according to the present embodiment will be described. First, operation of the refrigerant circuit will be described. A refrigerant compressed to have a high temperature and a high pressure by the compressor 2 flows into the water-refrigerant heat exchanger 3 through the refrigerant piping Ga. Water fed by a pump (not illustrated) provided inside or outside of the housing 9 flows into the water-refrigerant heat exchanger 3 from a water piping 8a. In the water-refrigerant heat exchanger 3, heat exchange is performed between the water flowed from the water piping 8a and the high-temperature, high-pressure refrigerant sent from the compressor 2, whereby the water is heated and becomes hot water and flows out from a water piping 8b. Also, the high-temperature, high-pressure refrigerant is cooled as a result of the heat exchange with the water and enters a low-temperature, high-pressure state, and flows into the expansion valve 4 through the refrigerant piping 6b. Then, the refrigerant is decompressed into a low-pressure state by the expansion valve 4 and flows into the air heat exchanger 5 through the refrigerant piping 6c. The low-temperature, low-pressure refrigerant flowed into the air heat exchanger 5 exchanges heat with air sent from the propeller fan 15 and is thereby heated and evaporated and gasified. Then, the gasified refrigerant flows out from the air heat exchanger 5 and is drawn into the compressor 2 through the refrigerant piping 6d. A heat pump cycle is configured as described above.

[0022] Next, a flow of air caused by the air blower 7 will be described. Upon the propeller fan 15 being driven to rotate by the fan motor 16, the pressure side I 5a of the propeller fan 15 discharges air in a region of rotation of the blades (path on which the blades rotate) to the outside of the housing 9 from the round opening 19 of the front panel 9b and pressure on the suction side 15b side is lowered and air is drawn into the region of rotation of the blades. Because of decrease in pressure of the inside of the entire air -12 -passage chamber 13 due to the drawing-in action of the propeller fan 15, air outside of the housing 9 is drawn into the air passage chamber 13 through the air heat exchanger 5. [0023] In the air heat exchanger 5 in the heat pump water heater 1 having the above-described structure, as can be seen from Figure 6, a part existing in a region that is lower than the center line of rotation of the propeller fan 15 is larger than a part that existing in a region that is higher than the center line of rotation of the propeller fan 15 Therefore, an amount of air flowing in the air passage chamber 13 tends to be large in the region that is lower than the center line of rotation of the propeller fan 15 compared to the region that is higher than the center line of rotation of the propeller fan 15.

[0024] With reference to Figures 8 and 9, a flow of air in the vicinity of the cooler box 14 in the heat pump water heater 1 will be described below. Arrows in these figures indicate air flows flowing into the clearances 20a and 20b between the back surface Na and the side surface 14b of the cooler box 14 and the air heat exchanger 5 and subsequent air flows.

[0025] As illustrated in Figures 8 and 9, air flowing into the clearance 20a through the back air heat exchanger 5a rises along the back surface 14a (airflow A in the figures). On the other hand, in the air flowing into the clearance 20b through the side air heat exchanger 5b, air flowing into from the back surface side relative to the inlet-side end 18a of the bellmouth 18 rises along the side surface 14b (airflow B in the figures). The airflow A and the airflow B run away from respective back surface and side surface corners of the upper surface 14c of the cooler box 14 and further rises beyond the upper -In -surface 14c and flows into an inner peripheral part close to the center in the region of rotation of the propeller fan 15.

[0026] In the air flowing into the clearance 20b through the side air heat exchanger 5b, air flowing into from a part of the side air heat exchanger 5b on the front side relative to the inlet-side end 18a of the bellmouth 18 rises along the side surface 14b (airflow C in the figures). A part of the airflow A and the air flowing through the side air heat exchanger 5b from an area around the level of the upper surface 14c of the cooler box 14 collides with the shield plate 21a. These airflows flow into the air passage chamber 13 from the front side relative to the inlet-side end 18a of the bellmouth 18 and flow into the propeller fan 15 from the back surface side relative to the inlet-side end 18a, and thus have a vector component from the front side toward the back surface side.

[0027] If no shield plate 21a is provided, a flow flowing into from the front side relative to the inlet-side end 18a collides and merges with the flows 22a and 22b rising in the clearances 20a and 20b between the back surface 14a and the side surface 14b and the air heat exchanger 5, on the upper surface 14c of the cooler box 14 In this case, when the airflows A and B from the clearances 20a and 20b flow into the region of rotation of the propeller fan 15, the flow flows into the inner peripheral part that is closer to the center. As a result, an non-uniform state in which in a part of the propeller fan 15 close to the cooler box 14, an amount of air flowing into an outer peripheral part of the region of rotation of the propeller fan 15 is small (the flow speed is low) and the amount of air flowing into the inner peripheral part close to the center is large (the flow speed is high) occurs. Therefore, each time a blade of the rotating propeller fan 15 passes above the -14 -cooler box 14, variation in direction and speed of air falling on the relevant front edge 15c and variation in pressure of a surface of the blade occur, which causes generation of aerodynamic rotation sound (noise) from the blade of the propeller fan 15.

[0028] On the other hand, in the heat pump water heater I according to the present embodiment, provision of the shield plate 21a enables reduction of the aforementioned aerodynamic rotation sound In other words, as illustrated in Figure 9, air flowing into from a part on the front side relative to the inlet-side end 18a of the bellmouth 18 is held back by the shield plate 21a before the air reaches the back surface side relative to the inlet-side end 18a of the bellmouth 18. Therefore, the airflow A raising along the back surface 14a of the cooler box 14 and the airflow B rising along a part of the side surface 14b on the back surface side relative to the inlet-side end 18a of the bellmouth 18 are prevented from interfering with a flow flowing into from the front side toward the back surface side. Consequently, the airflow A and the airflow B are prevented from addition of components from the front side toward the back surface side and thus flows into a part close to the outer periphery of the region of rotation of the propeller fan 15 As a result, non-uniformity in flow amount (flow speed) of air flowing into the outer peripheral part and the inner peripheral part is improved so as to achieve a uniform state in the part of the region of rotation from the part below the center line of rotation of the propeller fan IS and above the part of the cooler box on the side provided with the air heat exchanger 5. Consequently, variation in direction and speed of air falling on the front edge 15c and variation in pressure on the blade surfaces when the blades of the rotating propeller fan 15 pass above the upper surface 14c of the cooler box 14 are suppressed, enabling suppression of generation of aerodynamic rotation sound. Furthermore, aerodynamic -15 -rotation sound from the propeller fan can be reduced, enabling enhancement in rotation frequency of the propeller fan to increase in flow amount of air flowing through the air heat exchanger. Consequently, a low-input heat pump water heater that enhances the refrigerant cycle efficiency and reduces a compressor input can be provided.

[0029] Next, the shield plate 21b will be described with reference to Figure 10. Figure 10 is a diagram of the inside of the heat pump water heater 1 as viewed from the back side. In Figure 10, a view seen through the back air heat exchanger 5a and the side panel 9d is illustrated.

[0030] The rising airflow C colliding with the shield plate 21a becomes an airflow D that passes through an air passage formed by the shield plate 21a and an outer surface of the bellmouth 18, the front panel 9b and the upper surface 14c of the cooler box 14 and runs around to the separator 11 side.

[0031] Here, if no shield plate 21b is provided, the airflow D running around to the separator 11 side collides and merges with the airflow A raising in the clearance 20a between the back surface 14a of the cooler box 14 and the back air heat exchanger 5a, on a part of the upper surface I 4c of the cooler box 14 on the separator I I side. The airflow D flowing into the separator side includes a component flowing into from the front side to the back side when the airflow D collides with the airflow A, and thus, the airflow A subsequent to the merging flows into the inner peripheral part closer to the center when the airflow A flows into the region of rotation of the propeller fan 15. As a result, a non-uniform state in which an amount of air flowing into the part of the region of -16 -rotation of the propeller fan 15, the part being close to the outer periphery is small (the flow speed is low) and an amount of air flowing into the inner peripheral part close to the center is large (the flow speed is high) occurs. Thus, each time a blade of the rotating propeller fan 14 passes above the cooler box 14, variation in direction and speed of air falling on the relevant front edge 15c and variation in pressure on a surface of the blade occur, which causes generation of aerodynamic rotation sound (noise) from the blade of the propeller fan 15 [0032] On the other hand, in the heat pump water heater 1 according to the present embodiment, provision of the shield plate 21b enables reduction of the aforementioned aerodynamic rotation sound. In other words, the airflow D running around to the separator 11 side is held back by the shield plate 2 lb, preventing the airflow A rising along the back surface 14a of the cooler box 14 from interfering with the airflow D running around to the separator 11 side. Consequently, no component from the front side toward the back side is added to the airflow A raising along the back surface 14a of the cooler box 14, allowing the airflow A to flow into the part of the region of rotation of the propeller fan 15, the part being close to the outer periphery. As a result, non-uniformity in flow amount (flow speed) of air flowing into the outer peripheral part and the inner peripheral part is improved so as to achieve a uniform state in the part of the region of rotation below the center line of rotation of the propeller fan 15 and above the part of the cooler box 14 on the side provided with the air heat exchanger 5. Thus, variation in direction and speed of air falling on the front edge Sc1 and variation in pressure on the blade surfaces when blades of the rotating propeller fan 15 pass above the upper surface 14c of the cooler box 14 are suppressed, enabling suppression of generation -17 -of aerodynamic rotation sound Also, aerodynamic rotation sound from the propeller fan 15 can be reduced, enabling enhancement in rotation frequency of the propeller fan 15 to increase in flow amount of air flowing through the air heat exchanger. Consequently, a low-input heat pump water that enhances the refrigerant cycle efficiency and reduces a compressor input can be provided.

[0033] As described above, according to the heat pump water heater 1 of the present embodiment, the shield plates 21 are provided on the upper surface 14c of the cooler box 14, enabling reduction of aerodynamic rotation sound from an air blower while suppressing energy efficiency decrease.

[0034] Also, in the heat pump water heater 1 according to the present embodiment, the heights of the shield plates 21 are set so as to be higher than the inlet-side end 18a of the bellmouth 18 and provide a predetermined clearance between the outer peripheral surface of the bellmouth 18 and each of the shield plates 21. With such shield plates 21, when the airflow C held back by the shield plate 21 runs toward the separator 11 side, the airflow C flows into the region of rotation of the propeller fan 15 over the inlet-side end 18a of the bellmouth 18 while dispersing circumferentially from the aforementioned clearance. Consequently, the circumferential dispersion of the flow into the region of rotation of the propeller fan 15 prevents non-uniformity and thus allows equalization in speed of the flow into the region of rotation of the propeller fan. Thus, variation in direction and speed of air falling on the front edge 15c and variation in pressure on the blade surfaces when the blades of the rotating propeller fan 15 pass above the upper -18 -surface 14c of the cooler box 14 are suppressed, enabling effective suppression of generation of aerodynamic rotation sound.

[0035] Although the heat pump water heater 1 according to the above-described embodiment has been described in terms of a configuration in which both of the shield plates 21a and 21b are provided, provision of at least the shield plate 21a enables exertion of an aerodynamic noise reduction effect Reference Signs List [0036] 1 heat pump water heater, 2 compressor, 3 water-refrigerant heat exchanger, 4 expansion valve, 5 air heat exchanger 5a back air heat exchanger, 5b side air heat exchanger, 6 refrigerant piping, 7 air blower, 8 water piping, 9 housing, 9a bottom panel, 9b front panel, 9c side panel, 9d side panel, 9e back panel, 9f top panel, 10 fan grill, 11 separator, 12 machinery chamber, 13 air passage chamber, 14 cooler box, 14a back surface, 14b side surface, 14c upper surface, 15 propeller fan, 15a pressure side 15b suction side, 15c front edge, 16 fan motor, 17 motor support, 18 bellmouth, 18a inlet-side end, 18b minimum inner diameter portion, 19 round opening, 20 clearance, 21 shield plate