WO2011030678A1

WO2011030678A1 - Defrost heater control method for air conditioner

Info

Publication number: WO2011030678A1
Application number: PCT/JP2010/064589
Authority: WO
Inventors: 康弘内藤
Original assignee: 三菱重工業株式会社
Priority date: 2009-09-09
Filing date: 2010-08-27
Publication date: 2011-03-17
Also published as: JP5554038B2; SE536868C2; JP2011058708A; SE1100833A1

Abstract

Provided is a defrost heater control method for an air conditioner, whereby an antifreezing defrost heater provided on an outdoor unit base can be appropriately controlled to prevent a wasteful power consumption and to reliably prevent drain water from freezing again. In the defrost heater control method for an air conditioner, the antifreezing defrost heater is placed on the outdoor unit base, and is energized under the defrost conditions, to prevent drain water from freezing. The defrost heater control method is characterized in that the defrost heater is energized when the outside air temperature (ThO-A) and the outdoor heat exchanger temperature (ThO-R) are respectively not more than a predetermined temperature, and the difference between the outside air temperature (ThO-A) and the outdoor heat exchanger temperature (ThO-R) is not less than a predetermined value (A) determined in accordance with the outside air temperature (ThO-A), and is heated so as to have a constant temperature.

Description

Defrost heater control method for air conditioner

The present invention relates to a control method for a defrost heater that is laid on an outdoor unit base of an air conditioner and prevents freezing of drain water on the outdoor unit base during defrosting.

In heat pump type air conditioners, frost may be formed on the outdoor heat exchanger that functions as an evaporator during heating operation. Since heat exchange is hindered by this frost, when frost formation is detected, a defrost operation for removing the frost is performed. When the defrost operation is performed, the frost that has been frosted on the outdoor heat exchanger is melted and drained on the base of the outdoor unit, and then discharged to the outside through the drain discharge hole. However, in cold districts, it is easy to form frost, and the drain water dripped on the outdoor unit base may be re-frozen on the base before being discharged from the drain discharge hole at low outside air temperature. .

Therefore, in an air conditioner for cold regions, a defrost heater (seeds heater) is laid on the outdoor unit base, and if there is a risk of drain water freezing, the defrost heater is energized to heat the outdoor unit base. This prevents drain water from refreezing on the outdoor unit base and prevents the outdoor fan from being locked due to the accumulation of ice. For example, Patent Literature 1 discloses a device in which a thermostat is attached to an outdoor unit base, and when the thermostat reaches a set temperature, the heater is energized to prevent re-freezing of drain water. . Patent Document 2 discloses an apparatus in which the outside air temperature or the outdoor heat exchanger temperature is detected at the time of defrosting, and when the temperature is low, the heater is energized to prevent re-freezing of drain water. ing.

Furthermore, in Patent Document 3, a drain pan heater is provided in the drain pan installed at the lower part of the cooler for the refrigerator, the drain pan heater is energized during the defrost operation, and energization is continued for a predetermined time after the defrost is completed. A system is proposed in which drain water is prevented from refreezing, and the delay off time of the drain pan heater is varied according to the set temperature of the refrigerator to prevent unnecessary energization.

Japanese Examined Patent Publication No. 61-6310 (see FIG. 3) Japanese Utility Model Publication No. 4-10495 (see FIGS. 1 and 2) JP 2000-337756 A (see FIG. 2)

However, in the method of detecting that the outside air temperature and the heat exchanger temperature have fallen below the set temperature and energizing the defrost heater, the outdoor heat exchanger is not frosted even if the outside air temperature and the heat exchanger temperature are low. That is, even in a situation where drain water is not generated and there is no possibility of freezing on the base, the defrost heater may be energized, and power is consumed unnecessarily, which is contrary to energy saving.

Furthermore, when the defrost heater is energized at the start of the defrost operation, there is a risk of refreezing due to the drain water falling on the unheated base, and in particular, frost and ice remain on the outdoor unit base. In such a case, the possibility is high, and smooth drainage of the drain water is hindered. As a result, it accumulates as ice and may cause a fan lock or the like. Further, if the defrost heater is continuously energized during the defrost operation, the fan is generally stopped, so that the defrost heater may be blown, which may cause problems due to excessive temperature rise.

The present invention has been made in view of such circumstances, and appropriately controls a defrost heater for anti-freezing provided on an outdoor unit base to prevent wasteful power consumption and recycle drain water. An object of the present invention is to provide a defrost heater control method for an air conditioner that can reliably prevent freezing.

In order to solve the above-described problems, the defrost heater control method for an air conditioner according to the present invention employs the following means.
That is, in the method for controlling a defrost heater for an air conditioner according to an aspect of the present invention, a defrost heater for preventing freezing is laid on an outdoor unit base, and the defrost heater is energized under the defrost condition to In the defrost heater control method for an air conditioner that prevents the drain water from freezing in the room, the defrost heater has an outside air temperature and an outdoor heat exchanger temperature that are lower than a set temperature, and the outside air temperature and the outdoor heat exchanger temperature. When the temperature difference is greater than or equal to a set value determined according to the outside air temperature, it is energized and heated to a constant temperature.

According to the defrost heater control method for an air conditioner according to one aspect of the present invention, the defrost heater has an outside air temperature and an outdoor heat exchanger temperature that are equal to or less than a set temperature, respectively, and the outside air temperature and the outdoor heat exchanger temperature. Is energized only when the temperature difference is equal to or greater than a set value determined according to the outside air temperature. Therefore, even if the outdoor air temperature and the outdoor heat exchanger temperature are each equal to or lower than the set temperature, if there is no possibility that the outdoor heat exchanger will be frosted, the defrost heater is not energized, and the difference between the outdoor air temperature and the outdoor heat exchanger temperature The defrost heater is energized and heated to a constant temperature only when the temperature difference is equal to or greater than the set value determined according to the outside air temperature and the defrost heater is included. Therefore, it is possible to minimize the energization of the defrost heater and to save energy by avoiding unnecessary power consumption.

In the above defrost heater control method for an air conditioner, the defrost heater is energized before the defrost operation of the outdoor heat exchanger is started, and is deenergized when the outdoor fan is stopped by the start of the defrost operation. Also good.

According to this control method, the defrost heater is energized before the defrost operation of the outdoor heat exchanger is started, and is deenergized when the outdoor fan is stopped due to the start of the defrost operation. Therefore, the defrost operation of the outdoor heat exchanger is performed. Before the operation is started, the outdoor unit base can be preheated with a defrost heater. Therefore, even if there is residual ice on the outdoor unit base, it can be removed in advance, and the drain water dripped from the outdoor heat exchanger can be re-frozen on the cold base at the start of defrosting. Can be prevented. In addition, during the defrost operation, the defrost heater is de-energized as the outdoor fan is stopped. Therefore, it is possible to prevent overheating due to the defrost heater being blown. During the defrost operation, the drain water flowing down on the outdoor unit base is heated by the outdoor heat exchanger, so there is no fear of refreezing.

In the above-described defrost heater control method for an air conditioner, the defrost heater may be energized again after the defrost operation is completed and the outdoor fan is resumed, and may be forcibly energized for a predetermined time.

According to this control method, the defrost heater is re-energized when the defrost operation is completed and the outdoor fan is resumed, and is forcedly energized for a predetermined time. Therefore, the amount of drain water after the defrost operation is the largest. Even if the heating operation is restarted before the drain water is completely discharged from the base under the condition that it is likely to be re-frozen, the drain water is heated by the defrost heater that is forcibly energized for a predetermined time. Freezing can be reliably prevented. Therefore, problems such as accumulation due to refreezing of drain water and fan locks resulting therefrom can be solved.

In the above-described defrost heater control method for an air conditioner, the predetermined time may be varied according to the number of defrosts, the defrost interval, the operating state of the outdoor fan, the accumulated operation time of the compressor, and the like.

According to this control method, the time during which the defrost heater is forcibly energized is variable depending on the number of defrosts, the defrost interval, the outdoor fan operating state, the compressor operating cumulative time, etc. The time for forced energization can be finely controlled according to the operating condition of the air conditioner and the time for energization can be made more appropriate and shorter. Also by this, useless power consumption can be suppressed and energy saving can be achieved.

In any of the above-described defrost heater control methods for an air conditioner, the defrost heater may be controlled to be turned on / off by a thermostat that detects a surface temperature of the defrost heater.

According to this control method, the defrost heater is on / off controlled by a thermostat that detects the surface temperature of the defrost heater. Therefore, the surface temperature of the defrost heater is detected by the thermostat, and the defrost heater is turned off at a set temperature or more and below the set temperature. By turning on at, the surface temperature can be controlled within an appropriate range. Therefore, freezing of drain water can be surely prevented, and excessive temperature rise can be prevented, wasteful power consumption can be suppressed, and energy can be saved.

According to the present invention, even if the outdoor air temperature and the outdoor heat exchanger temperature are equal to or lower than the set temperature, the defrost heater is not energized and the outdoor air temperature and the outdoor heat exchanger temperature are not energized when there is no fear of the frost heater The defrost heater is energized and heated to a constant temperature only when the temperature difference between the defrost heater is greater than the set value determined according to the outside air temperature and the defrost heater is included. It is possible to save energy by minimizing it and avoiding unnecessary power consumption.

It is a disassembled perspective view of the outdoor unit to which the defrost heater control method of the air conditioner concerning a 1st embodiment of the present invention is applied. It is a disassembled perspective view of the defrost heater and outdoor heat exchanger which are installed on the base of the outdoor unit shown in FIG. It is a perspective view of the state which laid the defrost heater on the base of the outdoor unit shown in FIG. It is a control flowchart figure of a defrost heater. It is a figure showing the entrance (on) condition of a defrost heater. It is a figure showing the relationship between the defrost heater and the entering condition of a defrost. It is a figure showing the entering (on) condition of a defrost. It is a control timing chart figure of a defrost heater.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows an exploded perspective view of an outdoor unit of an air conditioner to which the present invention is applied, FIG. 2 shows an exploded perspective view of its main part, and FIG. 3 shows a defrost heater. A perspective view of the laid state is shown.
An outdoor unit 1 of an air conditioner includes a laterally long rectangular casing 7 including an outdoor unit base 2, a front and left side panel 3, a right side panel 4, a service cover 5, a top panel 6, and the like. ing.

The inside of the housing 7 is partitioned into a machine chamber 9 side and a heat exchanger chamber 10 side by a partition plate 8, and in addition to a compressor (compressor or compressor) 11, piping 12, A four-way switching valve (four-way valve), an expansion valve, a control box, and the like are disposed, and on the heat exchanger chamber 10 side, an outdoor heat exchanger 13, an outdoor fan 14, and a defrost heater (heater for preventing freezing of the outdoor unit base 2). ) 15 etc. are provided. Among these devices, the compressor 11, the outdoor heat exchanger 13, the outdoor fan 14, and the defrost heater 15 are installed on the outdoor unit base 2.

As shown in FIG. 3, the outdoor unit base 2 is a dish-shaped rectangular press-molded product having an upward rising wall 16 in the periphery, and mounting legs 17 are integrally formed on the back surfaces near both the left and right sides. It is welded to. As shown in FIG. 3, on the bottom surface of the outdoor unit base 2, there are three installation seats 18 for installing the compressor 11 at the left position, and the outdoor fan 14 is installed at a position slightly to the right of the center. And an installation seat 20 for installing the outdoor heat exchanger 13 along the rear side (front side in FIG. 3) and the left side (right side in FIG. 3). There are four places. These installation seats 18, 19, 20 are formed in a convex shape upward by a predetermined height from the bottom surface of the outdoor unit base 2.

Further, the bottom of the outdoor unit base 2 is slightly lowered from the bottom of the base so as to be along the front side (the back side in FIG. 3) and the back side (the front side in FIG. 3) of the region on the heat exchanger chamber 10 side. The

drainage channels

21 and 22 are provided for collecting drain water on the bottom surface of the base and discharging the drain water to the outside.

Holes

23 and 24 are formed.

Moreover, in the drainage channel 22 provided in the bottom face of the outdoor unit base 2, as shown in FIGS. 2 and 3, the lower part of the outdoor heat exchanger 13 bent into an L shape is formed along the lower part. A defrost heater 15 is laid. The defrost heater 15 is formed by bending a rod-shaped sheathed heater, is laid along the drainage channel 22, and is fixed at two locations via brackets 25. Furthermore, a power supply harness 26 is connected to the defrost heater 15, and the surface temperature is detected, and the defrost heater 15 is turned off at a set temperature (for example, 35 ° C.) or more, and the set temperature (for example, for example) A thermostat 27 for preventing excessive temperature rise is provided to turn on the defrost heater 15 at 25 ° C. or lower.

Next, an energization control method for the defrost heater (heater) 15 will be described with reference to FIGS.
FIG. 4 is a control flowchart of the defrost heater 15. When the operation of the air conditioner is started, first, in step S1, it is determined whether the operation mode is “cooling” or “heating”. In the cooling mode, it is not necessary to energize the defrost heater 15, and the defrost heater 15 is turned off and returns to the start point. In the case of the heating mode, the process proceeds to step S2, and it is determined whether or not the compressor (compressor or compressor) 11 is being operated.

When it is determined in step S2 that the compressor 11 is in a stopped state, the defrost heater 15 is turned off and the process returns to the start time. When the compressor 11 is in an operating state, the process proceeds to step S3, where it is determined whether or not the air conditioner is defrosted. In the case of defrost “ON”, the defrost heater 15 is turned off and returns to the start point. In the case of defrost “OFF”, the process proceeds to step S4.

It should be noted that the defrost operation is started when, for example, the “defrosted condition” shown in FIG. 7 is satisfied. The “defrosting condition” may be an arbitrary condition, but here, the five conditions (a) to (e) shown in FIG. 7 are satisfied as the entering condition (ON condition). The defrost operation is performed by a known method such as a reverse cycle method, a normal cycle method, or a hot gas bypass method.

In step S4, it is determined whether or not the outdoor fan (outer fan motor) 14 is operating. If the outdoor fan 14 is stopped (off), the defrost heater 15 is turned off to return to the start point. If the outdoor fan 14 is operating (on), the process proceeds to step S5. Subsequently, in step S5, after the defrost operation is finished, it is determined whether or not it is within a predetermined time (for example, 5 minutes). If “YES”, the defrost heater 15 is turned on, and if “NO”. The process proceeds to step S6. Thus, the defrost heater 15 is forcibly energized for a predetermined time (5 minutes) after the defrost operation is completed.

In step S6, it is determined whether or not the defrost heater 15 satisfies the ON condition (ON condition). An example of the entry condition (ON condition) of the defrost heater 15 is shown in FIG. That is, when the defrost heater 15 satisfies the following four conditions (a) to (d), it is determined that the entry condition is satisfied (YES) and is turned on. The defrost heater 15 is turned off and returns to the start time.

(A) The operation mode is the heating mode.
(B) The outdoor heat exchanger temperature (heat exchange temperature) ThO-R detected by a heat exchange sensor (not shown) attached to the outdoor heat exchanger 13 is −2 ° C. or less (ThO-R ≦ −2). ° C).
(C) The temperature difference (ThO-A)-(ThO-R) between the outdoor air temperature ThO-A and the outdoor heat exchanger temperature ThO-R detected by the outdoor air temperature sensor (not shown) is the outdoor air temperature ThO-A. Is equal to or higher than a set value A determined according to ((ThO-A)-(ThO-R) ≧ A) (for example, as shown in FIG. 5, the outside air temperature ThO-A is 0 ° C. ≦ When ThO-A, A = 4.0, −5 ° C. ≦ ThO-A <0 ° C., A = 2.0, and −10 ° C. ≦ ThO-A <5 ° C., A = 1 .5, A = 1.0 when −15 ° C. ≦ ThO-A <10 ° C., A = −5.0 when ThO-A <−15 ° C.
(D) The outside air temperature ThO-A detected by the outside air temperature sensor is 0 ° C. or lower (ThO-A ≦ 0 ° C.).

Further, FIG. 6 shows respective operation start areas based on “conditions including defrost heater” and “conditions including defrost”. In other words, when the heating operation is performed, the relationship between the outdoor heat exchanger temperature ThO-R and the outdoor air temperature ThO-A is inevitably absorbed by the outdoor air in the case of an air heat source heat pump, and therefore inevitably the outdoor heat exchange. The chamber temperature ThO-R is lower than the outside air temperature ThO-A, and the relationship is less than the alternate long and short dash line, and the defrost heater inclusion condition includes the defrost operation region. For this reason, when the heating operation is started, the relationship between the outdoor heat exchanger temperature ThO-R and the outside air temperature ThO-A changes in the direction of the solid line arrow, so that after the defrost heater 15 is turned on, the defrost operation starts. Will be.

In the present embodiment, the “defrosted condition” is divided into two depending on the cumulative operation time of the compressor 11 depending on whether the cumulative operation time is 150 minutes or less, and the cumulative operation time ≧ 150 minutes. Since the time during which the heating operation is continued is longer than that in the case of the cumulative operation time ≦ 150 minutes and the frost is easily formed, the frost is not left undissolved by starting defrost earlier. Is set to However, if the defrosting condition is satisfied first, the defrost operation may be started before the defrost heater 15 is turned on.

As described above, the defrost heater 15 is a case where the operation mode is the heating mode and the compressor 11 and the outdoor fan (outer fan motor) 14 are both operated (ON), and the defrost heater inclusion condition is satisfied. In addition, power is supplied only when the defrost operation is not performed or when the defrost operation is within 5 minutes after the end of the defrost operation, and the outdoor unit base 2 is heated.

However, the defrost heater 15 is provided with a thermostat 27 for preventing excessive temperature rise that detects the surface temperature of the defrost heater 15 and controls the defrost heater 15 to be turned on / off. Since the defrost heater 15 is turned off at 35 ° C. or higher, and the defrost heater 15 is turned on at 25 ° C. or lower, the heating temperature is controlled within a certain range of 25 ° C. to 35 ° C. to prevent overheating. Yes.

FIG. 8 shows a control timing chart of the defrost heater 15 during the above-described defrost operation.
When the compressor 11 and the outdoor fan (outer fan motor) 14 are operating in an environment where frost formation is likely to occur on the outdoor heat exchanger 13 during the heating operation, the defrost heater 15 is satisfied when the defrost heater 15 is turned on. Is turned on and energization is started. Thereby, the outdoor unit base 2 is preheated to a predetermined temperature via the defrost heater 15 before the defrost operation is started. If the operation is continued in this state, as shown in FIG. 6, the defrosting condition is eventually satisfied and the defrost operation is started.

In the defrosting operation, the compressor 11 is temporarily stopped, the refrigeration cycle is switched from the heating cycle to the defrosting cycle by switching a four-way switching valve (not shown), the compressor 11 is restarted, and the outdoor It starts by stopping the fan 14. On the other hand, when the defrosting condition is satisfied, the compressor 11 is temporarily stopped to start the defrosting operation. As a result, the defrosting heater 15 is turned off, and the defrosting operation is continued while the defrosting operation continues. Energization) will continue.

When the frost of the outdoor heat exchanger 13 is defrosted by the defrost operation and the end of the defrost is detected due to the temperature rise of the outdoor heat exchanger 13 or the like, the compressor 11 is temporarily stopped and the operation of the outdoor fan 14 is started. As a result, the defrosting operation is terminated. At this time, the defrost heater 15 is forcibly energized for a predetermined time (5 minutes) regardless of whether the defrost heater inclusion condition is satisfied. Thereby, the defrost heater 15 starts heating and continues heating for a predetermined time (5 minutes) unless the outdoor fan (outer fan motor) 14 is stopped.

Thus, after the defrost operation is completed, the draining water flows down from the outdoor heat exchanger 13 onto the outdoor unit base 2 without delay by the heating action of the defrost heater 15 that is forcedly energized for a predetermined time. It is led to drain drain holes 23 and 24 provided at the lowest position via 22 and discharged to the outside without being re-frozen on the outdoor unit base 2.

Thus, according to the present embodiment, the following operational effects are obtained.
In the present embodiment, the temperature difference between the outdoor air temperature ThO-A and the outdoor heat exchanger temperature ThO-R is seen as the entry condition (on condition) of the defrost heater 15. This is because as the amount of frost in the outdoor heat exchanger 13 increases, the heat exchange is inhibited and the temperature difference between the outdoor air temperature ThO-A and the outdoor heat exchanger temperature ThO-R is increased. This is because the frost amount of the outdoor heat exchanger 13 is large and it is necessary to turn on the defrost heater 15 to turn on the defrost heater 15.

In other words, when the amount of frost in the outdoor heat exchanger 13 is small and the defrost heater 15 does not need to be turned on even when the outside air temperature is low, the outside air temperature ThO-A and the outside heat exchanger temperature ThO-R Small temperature difference. In such a case, unnecessary power consumption can be cut by turning off the defrost heater 15.
Therefore, it is possible to perform an efficient operation with the energization to the defrost heater (heater) 15 being the minimum necessary, and to save energy by avoiding unnecessary power consumption.

Further, the defrost heater 15 is energized before the defrost operation of the outdoor heat exchanger 13 is started, and is deenergized when the outdoor fan 14 is stopped by the start of the defrost operation. Before the defrosting operation of the heat exchanger 13 is started, the outdoor unit base 2 can be preheated by the defrost heater 15. As a result, even if there is residual ice on the outdoor unit base 2, it can be removed in advance and the drain water dripped from the outdoor heat exchanger 13 is cooled at the start of the defrost operation. Refreezing on the surface of the machine base 2 can be prevented. In addition, during the defrost operation, the defrost heater 15 is de-energized as the outdoor fan 14 is stopped. Therefore, it is possible to prevent an excessive temperature increase due to the defrost heater 15 being blown.

Further, the defrost heater 15 is re-energized when the defrost operation is completed and the outdoor fan 14 is resumed, and is forcedly energized for a predetermined time. Therefore, the drain water after the defrost operation is the largest. In addition, even if the heating operation is resumed before the drain water is completely discharged from the outdoor unit base 2 under the condition of being easily re-frozen, the drain water is heated by the defrost heater 15 that is forcibly energized for a predetermined time. Therefore, the refreezing can be surely prevented. Thereby, problems such as accumulation due to re-freezing of drain water and fan lock caused by it can be solved.

Further, since the defrost heater 15 is controlled to be turned on / off by a thermostat 27 that detects the surface temperature of the defrost heater 15, the surface temperature of the defrost heater 15 is detected by the thermostat 27, and the defrost heater 15 exceeds the set temperature. By turning off and turning on below the set temperature, the surface temperature can be controlled within an appropriate range. As a result, it is possible to reliably prevent the drain water from being frozen, to prevent excessive temperature rise, to suppress wasteful power consumption, and to save energy.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
The present embodiment differs from the first embodiment in the way of setting the energization time of the defrost heater 15 that is forcibly energized after the defrost operation is completed. Since other points are the same as those in the first embodiment, description thereof will be omitted.
In the first embodiment, the forced energization time is set to a fixed time, for example, 5 minutes, but this time is (a) the number of defrost operations, (b) the time interval of the defrost operation, (c) the outdoor fan. 14 operation states (Hi, Me, Lo, etc.), (d) the accumulated operation time of the compressor 11 and the like.

As described above, after the defrost operation is completed, the time for which the defrost heater 15 is forcibly energized is made variable according to the number of defrosts, the defrost interval, the operation state of the outdoor fan 14, the operation accumulated time of the compressor 11, and the like. Thus, after the defrost operation is completed, the time for which the defrost heater 15 is forcibly energized can be finely controlled according to the operating condition of the air conditioner, and the time for the forcible energization can be further optimized and shortened. Accordingly, it is possible to suppress wasteful power consumption and save energy.

In addition, this invention is not limited to the invention concerning the said embodiment, In the range which does not deviate from the summary, it can change suitably. For example, the specific numerical conditions of the defrost heater-containing condition and the defrost-containing condition described in the above embodiment are merely examples, and it goes without saying that the present invention is not limited to this.

Further, in the control timing chart of the defrost heater 15 shown in FIG. 8, when the compressor 11 is operated and stopped during the defrost operation, the rotation speed is controlled and the switching timing of the four-way switching valve is set to the compressor 11. It is shifted for several seconds with respect to the restart, and further, when the outdoor fan 14 is operated and stopped, the rotation speed is controlled. However, these controls are within the range described in the above embodiment. It can be changed as appropriate.

1 Outdoor unit 2 Outdoor unit base 11 Compressor (compressor or compressor)
13 Outdoor heat exchanger 14 Outdoor fan (outer fan motor)
15 Defrost heater (heater)
27 Thermostat ThO-A Outdoor temperature ThO-R Outdoor heat exchanger temperature (heat exchange temperature)
A Setting value

Claims

In the defrost heater control method for an air conditioner in which a defrost heater for preventing freezing is laid on the outdoor unit base and energizes the defrost heater under defrost conditions to prevent the drain water from freezing on the outdoor unit base.
The defrost heater is energized when the outside air temperature and the outdoor heat exchanger temperature are each not more than a set temperature, and the temperature difference between the outside air temperature and the outdoor heat exchanger temperature is not less than a set value determined according to the outside air temperature. A method for controlling a defrost heater of an air conditioner, characterized by being heated to a constant temperature.
2. The air conditioner according to claim 1, wherein the defrost heater is energized before the defrost operation of the outdoor heat exchanger is started, and is de-energized when the outdoor fan is stopped by the start of the defrost operation. Defrost heater control method.
3. The defrost heater control method for an air conditioner according to claim 2, wherein the defrost heater is re-energized when the defrost operation is finished and the outdoor fan is restarted, and is forcedly energized for a predetermined time. .
4. The method of controlling a defrost heater for an air conditioner according to claim 3, wherein the predetermined time is varied according to the number of defrosts, the defrost interval, the outdoor fan operating state, the compressor accumulated operation time, and the like.
The defrost heater control method for an air conditioner according to any one of claims 1 to 4, wherein the defrost heater is on / off controlled by a thermostat that detects a surface temperature of the defrost heater.