EP2426428A1

EP2426428A1 - Air-conditioning apparatus

Info

Publication number: EP2426428A1
Application number: EP11006360A
Authority: EP
Inventors: Masahiko Takagi; Kiyoshi Yoshimura
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2010-09-01
Filing date: 2011-08-02
Publication date: 2012-03-07
Anticipated expiration: 2031-08-02
Also published as: ES2402983T3; JP5295189B2; EP2426428B1; JP2012052743A

Abstract

An air-conditioning apparatus (100 (200)) capable of air-conditioning operation and provided with a drain pan (9) that collects condensed water (13) caused in a heat exchanger as drain water (12) includes: a drain pump (10) drains the drain water (12) collected in the drain pan (9); and a controller (60 (201)) controls the drain pump (10), compares a rotation speed (current value to be supplied) of the drain pump (10) with a preset reference value of rotation speed (V) (reference value of current (I)), and determines the presence or absence of a sign of drain failure of the drain pump (10) on the basis of the result of the comparison.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air-conditioning apparatus.

2. Description of the Related Art

Conventionally, various types of air-conditioning apparatus in which a water level detecting unit detects a water level in a drain pan that collects drain water caused in a heat exchanger, and in which a drain pump is driven on the basis of the detected water level to drain the drain water are proposed (for example, see patent literature 1).
The air-conditioning apparatus may suffer from drain failure caused by increased viscosity of the drain water, failure of the drain pump, and foreign substances clogged up in a drain path connected to the drain pump during operation. In such a case, in an air-conditioning apparatus such as the one described in patent literature 1, when the water level in the drain pan rises and water level sensing means detects that the water level has exceeded a predetermined level, the operation is stopped on the basis of the detected result to prevent overflow of the drain water from the drain pan.

Citation List

Patent Literature

Patent literature 1: Japanese Unexamined Patent Application Publication No. 5-141686 (for example, Fig. 1)
In the technology disclosed in patent literature 1, a user recognizes the drain failure by the air-conditioning apparatus stopping its operation due to the drain failure and then goes about to repair the drain pump. Therefore, maintenance management is hard and it takes a fair amount of time until the air-conditioning apparatus recovers.

SUMMARY OF THE INVENTION

In order to solve the above-described problems, it is an object of the invention to provide an air-conditioning apparatus, which facilitates maintenance management by detecting a sign of drain failure.
An air-conditioning apparatus according to the invention capable of air-conditioning operation and provided with a drain pan collects condensed water caused in a heat exchanger as drain water includes: a drain pump that drains the drain water collected in the drain pan; and a controller that controls the drain pump, compares the rotation speed of the drain pump with a preset reference value of rotation speed, and determines the presence or absence of a sign of drain failure of the drain pump on the basis of the result of the comparison.
According to the air-conditioning apparatus of the invention, since the sign of drain failure is detected, the user can easily manage maintenance of the air-conditioning apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a diagram illustrating a brief configuration of an air-conditioning apparatus according to Embodiment 1 of the invention;
Fig. 2 is a diagram illustrating a brief configuration of an air-conditioning apparatus according to Embodiment 2 of the invention; and
Fig. 3 illustrates a circuit example of a motor of a drain pump in the air-conditioning apparatus shown in Fig. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, embodiments of the invention will be described.

Embodiment 1

Fig. 1 is a diagram illustrating a brief configuration of an air-conditioning apparatus 100 according to Embodiment 1 of the invention. In the drawings below, including Fig. 1, the dimensional relationships of each component may be different from the actual relationships. The air-conditioning apparatus 100 includes a function to detect a sign of drain failure and prompt a user to perform maintenance in advance. In other words, the air-conditioning apparatus 100 is capable of prompting the user to perform maintenance before the air-conditioning apparatus 100 breaks down due to drain failure rendering the air-conditioning operation to become impossible.

[Refrigerant Cycle Configuration of Air-Conditioning Unit 100]

First, a refrigerant cycle configuration of the air-conditioning apparatus 100 will be described.
The air-conditioning apparatus 100 includes an indoor unit 101 and an outdoor unit 102.
The indoor unit 101 includes at least an indoor heat exchanger 2. An indoor fan 3 is provided in the vicinity of the indoor heat exchanger 2.
The indoor heat exchanger 2 is configured to function as an evaporator cooling air at the time of a cooling operation, and to function as a condenser (radiator) heating air at the time of a heating operation. The indoor heat exchanger 2 may be, for example, a cross-fin type fin-and-tube heat exchanger made up of a transfer tube and multiple fins.
The indoor fan 3 is configured to suck in indoor air into the indoor unit 101 and supply air that has exchanged heat with the refrigerant at the indoor heat exchanger 2 as air-conditioned air to an area subject to air conditioning. The indoor fan 3 includes a fan or the like which is capable of changing a flow rate of the to-be-air-conditioned air to be supplied to the indoor heat exchanger 2.
The outdoor unit 102 at least includes a condenser 4, an outdoor heat exchanger 5, and a throttle device 7. An outdoor fan 6 is provided in the vicinity of the outdoor heat exchanger 5.
The condenser 4 is a condenser capable of changing its operation capacity and, for example, may be a positive displacement compressor driven by a motor (not illustrated) controlled by an inverter. The condenser 4 is arranged between the outdoor heat exchanger 5 and the indoor heat exchanger 2.
The outdoor heat exchanger 5 is configured to function as a condenser (radiator) and transfers heat to air at the time of the cooling operation, and to function as an evaporator cooling air at the time of the heating operation. The outdoor heat exchanger 5 may be, for example, a cross-fin type fin-and-tube heat exchanger made up of a transfer tube and multiple fins.
The outdoor fan 6 is configured to suck in outdoor air into the outdoor unit 102 and blow out air outdoors that has exchanged heat with the refrigerant at the outdoor heat exchanger 5. The outdoor fan 6 is provided in the outdoor heat exchanger 5 and is formed of the fan or the like which is capable of changing a flow rate of air to be supplied to the outdoor heat exchanger 5.
The throttle device 7 is capable of changing an opening-degree of the throttle, and is configured to adjust a flow rate of the refrigerant flowing in the refrigerant cycle. The throttle device 7 is arranged between the outdoor heat exchanger 5 and the indoor heat exchanger 2.
Further, as shown in Fig. 1, the condenser 4, the outdoor heat exchanger 5, the throttle device 7, and the indoor heat exchanger 2 are connected in series in a circular pattern by refrigerant pipes 103 and constitute the refrigerant cycle. Therefore, the air-conditioning apparatus 100 is configured to perform the cooling or heating operation by circulating the refrigerant in the refrigerant cycle. Although the refrigerant cycle at the time of the cooling operation is illustrated in Fig. 1, needless to say, the operation can be appropriately switched to a heating operation using a four-way valve (not illustrated).
In the air-conditioning apparatus 100, condensed water 13 is formed on the surface of the indoor heat exchanger 2 due to decrease in the surface temperature of the indoor heat exchanger 2 especially at the time of the cooling operation and is collected in a drain pan 9 as drain water 12. The drain water 12 collected in the drain pan 9 is configured to be appropriately drained by a drain pump 10, so that the drain water 12 is prevented from overflowing from the drain pan 9 and dropping to an area subject to air conditioning (not illustrated, for example, a room). A configuration of the indoor unit 101 (configuration other than the refrigerant cycle) will be described below.

[Configuration of Indoor Unit 101 (Configuration other than Refrigerant Cycle)]

As shown in Fig. 1, the indoor unit 101 includes the drain pan 9, the drain pump 10, a rotation speed sensing device 16, a water level sensing device 11, drain piping 22, a controller 60, and a display unit 70 other than the indoor fan 3, described above.
The drain pan 9 is configured to collect the condensed water 13 formed on the indoor heat exchanger 2 as the drain water 12. The drain water 12 in the drain pan 9 increases by an amount of the condensed water 13 dropping from the indoor heat exchanger 2, and decreases by an amount drained by the drain pump 10. The place to mount the drain pan 9 may be below the indoor heat exchanger 2 in the substantially perpendicular direction as shown in Fig. 1.
The drain pump 10 is configured to drain the drain water 12 in the drain pan 9 to the outside of the indoor unit 101. The place to mount the drain pump 10 may be above the drain pan 9 in the substantially perpendicular direction as shown in Fig. 1. The drain pump 10 includes a casing 20, a motor 17, a shaft 18, and an impeller 21.
The casing 20 is formed with an inlet opening 14 for sucking the drain water 12 and a discharge opening 15 for draining the drain water 12. The casing 20 is also provided with the impeller 21. The inlet opening 14 is configured to suck the drain water 12 collected in the drain pan 9 into the casing 20. The inlet opening 14 is preferably provided, for example, at a position facing a bottom surface of the drain pan 9 as shown in Fig. 1. The discharge opening 15 is configured to drain the drain water 12 sucked into the casing 20 out of the casing 20. The discharge opening 15 is connected to the drain piping 22.
The motor 17 is configured to rotate the shaft 18 by power supplied thereto. The motor 17 is connected to a power source (not illustrated). The motor 17 is also controlled by the controller 60 in the same manner as the indoor fan 3.
The shaft 18 is configured to connect the motor 17 and the impeller 21 and transmit a rotational force of the motor 17 to the impeller 21. In other words, since the shaft 18 is connected to the impeller 21, the impeller 21 is configured to rotate together with an axial rotation of the shaft 18.
The impeller 21 is configured to, by its own rotation, suck the drain water 12 into the casing 20 via the inlet opening 14 and drain the sucked drain water 12 from the discharge opening 15. Since the impeller 21 is substantially disk shaped and its center is fixed to be concentric with the shaft 18, the impeller 21 rotates together with the rotation of the shaft 18.
The rotation speed sensing device 16 is configured to detect the rotation speed of the shaft 18. The rotation speed sensing device 16 is configured to send the detected rotation speed of the shaft 18 to the controller 60 as rotation speed data A. The rotation speed sensing device 16 is also preferably mounted, for example, adjacent to the shaft 18. The description will be made with the air-conditioning apparatus 100 employing a system with a magnet (not illustrated) attached to the shaft 18, in which the rotation speed of the shaft 18 is detected by detecting the change of magnetic field generated by the rotation of the magnet by the rotation speed sensing device 16. The method of detecting the rotation speed of the shaft 18 is not specifically limited to the above-described system.
The water level sensing device 11 is configured to detect the water level of the drain water 12 collected in the drain pan 9. The water level sensing device 11 is configured to send the detected water level of the drain water 12 in the drain pan 9 to the controller 60 as water level data C. The water level sensing device 11 is preferably mounted, for example, above the drain pan 9 in the perpendicular direction. Since the water level in the drain pan 9 may be detected by detecting the rotation speed of the shaft 18 by the rotation speed sensing device 16, the water level sensing device 11 may not be provided.
The drain piping 22 is configured to drain the drain water 12 drained from the discharge opening 15 to the outside of the indoor unit 101. The drain piping 22 is connected at one end thereof to the discharge opening 15, and the other end of the drain piping 22 and is preferably placed, for example, outside the area subject to air conditioning (for example, outdoors).
The controller 60 is configured to control the rotations of the indoor fan 3 and the motor 17 and the display of the display unit 70. The controller 60 receives the rotation speed data A from the rotation speed sensing device 16 and sends a drain failure indicating signal A2 for controlling the display unit 70 based on the rotation speed data A. More specifically, the controller 60 is configured to determine whether or not there is a sign of drain failure on the basis of the rotation speed data A, and if it is determined that there is a sign of drain failure, sends the drain failure indicating signal A2 to the display unit 70. The drain failure indicating signal A2 is a control signal for indicating on the display unit 70 to notify the user the fact that there is a sign of drain failure of the drain pump 10.
The controller 60 receives the water level data C from the water level sensing device 11, and sends a repair indication signal C2 for controlling the display unit 70 and a stop signal D for controlling the indoor fan 3 and the condenser 4 based on the water level data C. More specifically, the controller 60 determines whether or not the water level is higher than a predetermined water level on the basis of the water level data C, and if it is determined that it is higher than a predetermined water level, sends the repair indication signal C2 to the display unit 70 and sends the stop signal D to the indoor fan 3 and the condenser 4.
The repair indication signal C2 is a control signal for indicating on the display unit 70 to notify the user the fact that the water level of the drain water 12 in the drain pan 9 is higher than the predetermined level. In addition, the stop signal D is a control signal to stop the operations of the indoor fan 3 and the condenser 4 to prevent the drain water 12 in the drain pan 9 from rising in level and overflowing from the drain pan 9.
The display unit 70 is configured to receive the drain failure indicating signal A2 and the repair indication signal C2 from the controller 60 so as to notify the user of the sign of drain failure of the drain pump 10 and prompt the user to perform maintenance in advance or notify the user of the fact that maintenance is necessary when the water level of the drain water 12 in the drain pan 9 has increased to a level higher than the predetermined value. Although the description will be made with the display unit 70 provided on the indoor unit 101, it may be provided on a remote controller (not illustrated). It is also possible to prompt the user to perform maintenance or notify the fact that maintenance is necessary using a speech sound or the like, and hence the display unit 70 does not have to be provided.

[Description of Operation]

Subsequently, the treatment of the drain water 12 in the cooling operation of the air-conditioning apparatus 100 will be described.
When the cooling operation starts, the surface temperature of the indoor heat exchanger 2 drops. Then, the air sucked into the indoor unit 101 by the indoor fan 3 is sent to the indoor heat exchanger 2 and is cooled therein. When the temperature of the cooled air reaches a dew-point or below, condensed water 13 is formed on the surface of the indoor heat exchanger 2 from moisture in the air, and is collected in the drain pan 9 as the drain water 12. The drain water 12 collected in the drain pan 9 is appropriately drained by the drain pump 10. At this time, if a drain path clogs up, the viscosity of the drain water 12 increases, or the drain capability of the drain pump 10 drops, the rotation speed of the shaft 18 drops accordingly.
The rotation speed sensing device 16 detects the rotation speed of the shaft 18, and sends the rotation speed data A based on the rotation speed of the shaft 18 to the controller 60. When the controller 60 determines the rotation speed data A to have a sign of drain failure, the controller 60 sends the drain failure indicating signal A2 to the display unit 70. The display unit 70 displays an indication notifying the user of the fact that there is a sign of drain failure of the drain pump 10 upon receipt of the drain failure indicating signal A2. When the drain pump 10 shows sign of drain failure, the display unit 70 detects the sign and prompts the user to perform maintenance in advance as described above.
If the water level of the drain water 12 in the drain pan 9 rises to the predetermined value, the controller 60 sends the stop signal D to the indoor fan 3 and the condenser 4 to stop the operations of the indoor fan 3 and the condenser 4, and sends the repair indication signal C2 to the display unit 70 to make the display unit 70 to notify the user of the fact that maintenance is necessary.

[Drain Failure]

The drain failure is a phenomenon in which the amount of drained water by the drain pump 10 decreases caused by clogging in the drain path (the casing 20 and the drain piping 22) (draining state S1), increase of viscosity of the drain water 12 (draining state S2), or drop of draining capability of the drain pump 10 (draining state S3). In the air-conditioning apparatus 100, the controller 60 compares the rotation speed of the shaft 18 with the preset reference value of rotation speed V and determines the presence or absence of the sign of drain failure (any one of the draining state S1 to draining state S3) of the drain pump 10 on the basis of the result of the comparison. If it is determined that the sign of drain failure is present, the controller 60 controls the display unit 70 to display that there is a sign of drain failure, so that the user is notified.
When the motor 17 is driven at a uniform voltage, there may be a case in which the rotation speed determining the sign of drain failure may change due to the distance from the inlet opening 14 to the bottom surface of the drain pan 9 or the length (head of fluid) of the drain piping 22 or the like. In such a case, the reference value of rotation speed V may be calculated from the rotation speed of the air conditioning apparatus 100 when it is initially installed and is operating normally.
There is also a case where the rotation speed determining the sign of drain failure may change when components that constitute the drain pump 10 are replaced or when the drain piping 22 is replaced. In such a case, the controller 60 may be configured to be able to determine and change (renew) the preset reference value of rotation speed V.
It is further possible to configure the controller 60 to be able to increase the output of the motor 17 by increasing the voltage supplied from the power source to the motor 17 when the controller 60 determines that there is a sign of drain failure. By increasing the output of the motor 17 in this manner, time allowance until a draining state S4, in which the drain water 12 in the drain pan 9 becomes substantially undrainable (lowering of the drain capability to an unacceptable value or below), is reached can be prolonged.
Furthermore, two reference values of rotation speed V may be provided so that the controller 60 is capable of determining the draining state S4 in which the drainage is no longer achieved as well as the sign of drain failures (draining state S1 to draining state S3) of the drain pump. By providing the two reference values of rotation speed V in this manner, the controller 60 can determine the state to be the draining state S4 when the rotation speed of the shaft 18 decreases to a value below a second reference value of rotation speed V2. Subsequently, the controller 60 can control the display unit 70 to display the fact that the state is in the draining state S4, so that the user is notified. When the drain pump 10 is determined to be in the draining state S4, the controller 60 will control the operation of the indoor fan 3 and the condenser 4 to stop (stopping the air-conditioning operation). Therefore, needless to say, the water level sensing device 11 is no longer necessary because the air-conditioning apparatus 100 determines to stop the operation not on the basis of the water level of the drain water 12 in the drain pan 9 detected by the water level sensing device 11, but on the basis of the rotating speed of the rotation speed sensing device 16.
The controller 60 may be configured to compare the rotation speed of the shaft 18 with a plurality of preset reference values of rotation speed and determine the presence or absence of only one sign out of the draining states S1 to S4 based on the result of the comparison. In contrast, the controller 60 may be configured to compare the rotation speed of the shaft 18 with a single preset reference value of rotation speed and determine the presence or absence of signs of a plurality of the draining states based on the result of the comparison. (The number-of the reference values of rotation speed to be provided is not specifically limited.)

[Advantages of Air-Conditioning Unit 100]

Since the air-conditioning apparatus 100 is configured to detect the sign of drain failure by detecting the rotation speed of the drain pump 10, the user can easily control the air-conditioning apparatus 100. In addition, since the air-conditioning apparatus 100 is configured to detect the sign of drain failure of the drain pump 10, needless to say, the number of times of inspection of the drain pump 10 can be reduced.

Embodiment 2

Fig. 2 is a diagram illustrating a brief configuration of an air-conditioning apparatus 200 according to Embodiment 2. Fig. 3 illustrates an example of a circuit diagram of the motor 17 of the drain pump 10 in the air-conditioning apparatus 200 shown in Fig. 2. In Embodiment 2, the same parts as in Embodiment 1 are designated by the same reference numerals, and points different from Embodiment 1 are mainly described.
As shown in Fig. 3, a controller 201 is connected to an inverter circuit 202 configured to control the rotation speed of the motor 17 and a current sensor 205 configured to sense a current value supplied to the motor. The current sensor 205 may be of a type that is mounted to a wiring K position that detects the current from the change of magnetic flux. As shown in Fig. 2, the controller 201 receives a current value F from the current sensor 205, and sends the drain failure indicating signal A2 to control the display unit 70 based on the current value F.
As the drain failure progresses, the controller 201 increases a switching frequency of the inverter circuit 202, performing feedback control to restrain the rotation of the motor 17 from deceasing. In other words, the current supplied to the drain pump 10 increases as the drain failure progresses. Furthermore, the current value F supplied to the motor 17 appropriately changes, so that the signs of the draining states S1 to S4 can be determined by detecting the change of the current value F. In other words, in the air-conditioning apparatus 200, the controller 201 compares the current value F supplied to the motor 17 with a preset reference value of current I and determines the presence or absence of the sign of drain failure (any one of the draining state S1 to draining state S3) of the drain pump 10 on the basis of the result of the comparison. If it is determined that the sign of drain failure is present, the controller 201 controls the display unit 70 to display that there is a sign of drain failure, so that the user is notified. Although the inverter circuit 202 is described as being provided in the controller 201, the place to mount is not limited.
When the motor 17 is driven at a uniform voltage, there may be a case in which the current value determining the sign of drain failure may change due to the distance from the inlet opening 14 to the bottom surface of the drain pan 9 or the length (head of fluid) of the drain piping 22 or the like. In such a case, the reference value of current value I may be calculated from the current value of the air conditioning apparatus 200 when it is initially installed and is operating normally.
There is also a case where the current value determining the sign of drain failure may change when components that constitute the drain pump 10 are replaced or when the drain piping 22 is replaced. In such a case, the controller 201 may be configured to be able to determine and change (renew) the preset reference value of current value I.
It is further possible to configure the controller 60 to increase the output of the motor 17 by increasing the voltage supplied from the power source to the motor 17 when the controller 201 determines that there is a sign of drain failure. By increasing the output of the motor 17 in this manner, time allowance until the draining state S4, in which the drain water 12 in the drain pan 9 becomes substantially undrainable (lowering of the drain capability to an unacceptable value or below), is reached can be prolonged.
Furthermore, two reference values of current I may be provided so that the controller 201 is capable of determining the draining state S4 in which the drainage is no longer achieved as well as the sign of drain failures (draining state S1 to draining state S3) of the drain pump. By providing the two reference values of current I in this manner, the controller 201 can determine the state to be the draining state S4 when the current value F increases to a value higher than a second reference value of current I2. Subsequently, the controller 201 can control the display unit 70 to display the fact that the state is the draining state S4, so that the user is notified. When the drain pump 10 is determined to be in the draining state S4, the controller 201 will control the operation of the indoor fan 3 and the condenser 4 to stop (stopping the air-conditioning operation). Therefore, needless to say, the water level sensing device 11 is no longer necessary because the air-conditioning apparatus 200 determines to stop the operation not on the basis of the water level of the drain water 12 in the drain pan 9 detected by the water level sensing device 11, but on the basis of the current value F supplied to the drain pump 10.
The controller 201 may be configured to compare the current value F of the current supplied to the drain pump 10 with a plurality of preset reference values of current I and determine the presence or absence of only one sign out of the draining states S1 to S4 based on the result of the comparison. In contrast, the controller 201 may be configured to compare the current value F of the current supplied to the drain pump 10 with a single preset reference value of current I and determine the presence or absence of signs of a plurality of the draining states based on the result of the comparison. (The number of the reference values of current I to be provided is not specifically limited.)

[Advantages ofAir-Conditioning Unit 200]

Since the air-conditioning apparatus 200 is configured to detect the sign of drain failure by detecting the value of current supplied to the drain pump 10, the user can easily manage maintenance of the air-conditioning apparatus 200. In addition, since the air-conditioning apparatus 200 is configured to detect the sign of drain failure of the drain pump 10, needless to say, the number of times of inspection of the drain pump 10 can be reduced.
Needless to say, the contents described in Embodiments 1 and 2 may be appropriately combined.

REFERENCE SIGNS LIST

2 indoor heat exchanger, 3 indoor fan, 4 condenser, 5 outdoor heat exchanger, 6 outdoor fan, 7 throttle device, 9 drain pan, 10 drain pump, 11 water level sensing device, 12 drain water, 13 condensed water, 14 inlet opening, 15 discharge opening, 16 rotation speed sensing device, 17 motor, 18 shaft, 20 casing, 21 impeller, 22 drain piping, 60 controller, 70 display unit, 100 air-conditioning apparatus, 101 indoor unit, 102 outdoor unit, 103 refrigerant pipes, 200 air-conditioning apparatus, 201 controller, 202 inverter circuit, 205 current sensor, A rotation speed data, A2 drain failure indicating signal, C water level data, C2 repair indication signal, D stop signal, S1 draining state, S2 draining state, S3 draining state, S4 draining state, V reference value of rotation speed, V2 second reference value of rotation speed, I reference value of current, I2 second reference value of current, F current value, K wiring.

Claims

An air-conditioning apparatus (100) capable of air-conditioning operation and provided with a drain pan (9) that collects condensed water (13) caused in a heat exchanger as drain water (12), comprising:
a drain pump (10) that drains the drain water (12) collected in the drain pan (9); and

a controller (60) that controls the drain pump (10), compares a rotation speed of the drain pump (10) with a preset reference value of rotation speed, and determines the presence or absence of a sign of drain failure of the drain pump (10) based on the result of the comparison.
The air-conditioning apparatus (100) of claim 1, wherein the controller (60) calculates the reference value of rotation speed from the rotation speed of the drain pump (10) when the air-conditioning apparatus (100) is initially installed and is operating normally.
The air-conditioning apparatus (100) of claim 1 or 2, wherein the controller (60) is capable of changing the reference value of rotation speed.
An air-conditioning apparatus (200) capable of air-conditioning operation and provided with a drain pan (9) that collects condensed water (13) caused in a heat exchanger as drain water (12), comprising:
a drain pump (10) drains the drain water (12) collected in the drain pan (9); and

a controller (201) controls the drain pump (10), compares a current value supplied to the drain pump (10) with a preset reference value of current, and determines the presence or absence of a sign of drain failure of the drain pump (10) based on the result of the comparison.
The air-conditioning apparatus (200) of claim 4, wherein the controller (201) calculates the reference value of current from the current value of the drain pump (10) when the air-conditioning apparatus (200) is initially installed and is operating normally.
The air-conditioning apparatus (200) of claim 4 or 5, wherein the controller (201) is capable of changing the reference value of current.
The air-conditioning apparatus (200) of any one of claims 1 to 6, wherein when the controller (201) determines that there is a sign of drain failure of the drain pump (10), the controller (201) controls to increase the rotation speed of the drain pump (10).
The air-conditioning apparatus (100) of any one of claims 1 to 3, wherein the controller (60) stops the air-conditioning operation when the rotation speed of the drain pump (10) is lower than a second reference value of rotation speed that is lower than the reference value of rotation speed.
The air-conditioning apparatus (200) of any one of claims 4 to 6 or claim 7 dependent from claims 4 to 6, wherein the controller (201) stops the air-conditioning operation when the current value of the drain pump (10) is higher than a second reference value of current which is higher than the reference value of current.
The air-conditioning apparatus (100, 200) of any one of claims 1 to 9, wherein when the controller (60, 201) determines that there is a sign of drain failure of the drain pump (10), the controller performs notification of the sign of drain failure.