Comparison Midea Mission II MB-09N8D6H 26 m² vs Indesit SPIW 409 LIN 25 m²

The British Thermal Unit (BTU) is used to indicate the rated capacity of air conditioners in cooling mode. The parameter is indicated mainly for split and multi split systems with wall installation. Capacity is indicated in BTU per hour, while 1 BTU/h is equal to about 0.293 watts. The rated capacity of an air conditioner is often a multiple of 1000 BTU. The indicator determines how many thousand BTU/h the air conditioning equipment provides. For example, the marking "9 BTU" here means a unit for 9000 BTU/h or about 2600 watts of effective capacity.

The practical meaning of the capacity is that by BTU you can easily determine the recommended area of a standard room in square meters: just multiply the figure indicated in the characteristics by 3. So, for 9 BTU it will correspond to 9*3=27 m². Note that there is no strict relationship between BTU and watts in this list: for example, air conditioners with an effective capacity of 2360 to 2900 W fall into the same category of 9 BTU. In practice, even such an approximate ratio is enough to understand which air conditioner should be considered for cooling certain area.

A very conditional parameter that slightly characterizes the purpose by the size of the room. And depending on the height of the ceilings, layout, structure of the building and equipment, the actual values ​​​​may differ significantly. Nevertheless, this item represents the maximum recommended area of ​​​​the room for using the air conditioner in the main mode – for cooling.

Most often, this parameter is indicated by a simplified formula: about 100 W of effective air conditioner power is required per 1 m2 of room area. Thus, for example, for a model with a cooling capacity of 2200 W, the recommended area will be 2200/100=22 m2. However, these results are relevant only for standard conditions in residential and office premises: ceiling height of about 2.5-3 m, no strong heat gain, etc. For more specific situations, there are more detailed calculation formulas, that can be found in special sources. Anyway, choosing an air conditioner according to the recommended area, it's ok to take a margin of at least 15-20%: this will give an additional guarantee that the device will be effective.

The recommended area up to 15 m2 for a modern air conditioner is considered very low; such units are designed to serve single rooms of a small area. For an average living room like a bedroom or living room, a 20 m2 or even 25 m2 model is better suited. Models of 30 m2 and above are already intended for at least studio apartments, and more often for office and industrial premises. And in the most powerful modern units, the recommended area can be 150 – 175 m2 or even more.

Note that the same general formula is used for the heating mode — “100 W per 1 m2”. At the same time, the effective power of most air conditioners in this mode is noticeably higher than in the cooling mode. So this item can also be used to select a unit with a heating function: an air conditioner capable of cooling a room of a certain area is almost guaranteed to be able to heat it (taking into account the relevant restrictions on the use — see "Operating modes").

Cooling and ventilation modes are in each model by definition. But air conditioners with humidification are relatively rare. For them, the opposite format is mandatory — dehumidification and heating.

- Cooling. The mode of lowering the air temperature in the room is the main function of any air conditioner. Note that conventional air conditioners, when cooled, also remove moisture from the air. However, due to a decrease in temperature, the relative humidity in this mode changes slightly (or does not change at all).

- Ventilation. The mode in which the air conditioner provides only air circulation throughout the room, without changing its temperature and humidity. Such a function can be useful, for example, for air mixing and temperature equalization; in addition, when passing through the air conditioner, the air is filtered, which is useful, for example, for cleaning from dust and smoke, or for ensuring hygiene in a room where a sick person is. Let us emphasize that ventilation must be distinguished from the fresh air intake(see "Functions"). The ability to add air from outside is rare and only in expensive models of air conditioners.

- Dehumidification. Mode for removing excess moisture from the air. This function works by condensing water vapour on the cold heat exchanger of the air conditioner; the collected mo...isture is usually removed to the outside through a drainage tube or accumulates in a special reservoir. Note that condensation also occurs in the cooling mode (see above); the dehumidification mode differs from it in that the temperature of the air passed through the air conditioner changes very slightly — usually by no more than 1 °C — but the humidity drops very noticeably.

— Heating. The mode of increasing the air temperature in the room. It should be borne in mind that most air conditioners with this function are not designed to be used as full-fledged heating systems - their task is to "help" such systems, as well as heating in the off-season, when the main heating does not work. In addition, the permissible outside temperature (see “Minimum t for heating mode”) can be different: for example, not every unit with a heating mode can work in cold weather. On the other hand, there are exceptions - powerful cold-resistant models, approaching the characteristics of heat pumps and withstanding temperatures of -25 ° C and even lower.

- Humidification. A need to increase air humidity often arises in winter. When the air is heated by heating devices, its relative humidity decreases (and the overall comfort in the room is associated precisely with relative humidity). In addition, in rooms where there are small children, it is recommended to specially humidify the air. The humidifying mode in air conditioners is rare and only in premium models. And for the operation of the humidifier, a supply of water is required, which must be monitored and periodically replenished.

— Fresh air intake. Ability to mix fresh air from outside with the air passed through the conditioner. Thus, models with this function not only change the temperature and humidity of the air but also additionally refresh it. On the other hand, mixing significantly complicates both the design of the air conditioner itself and its installation. Therefore, this function is rare, and mainly in models of the middle level and above.

— Automode. A function that relieves the user of the need to manually control the parameters of the air conditioner. It is enough just to set the desired microclimate in the room. After that, the unit will independently monitor the current conditions and select the desired operating mode. Most often, this function provides temperature monitoring and automatic switching between cooling and heating but advanced models may provide more advanced features, such as humidity monitoring with automatic dehumidification or even humidification.

— Night mode. A function that allows you to use the air conditioner as comfortably as possible at night. There are two main features of this mode. First, the fan speed is set to a minimum, which reduces noise and avoids strong air currents that can disturb sleepers. Secondly, the temperature change occurs very slowly and smoothly — by a couple of degrees within two to three hours; this is considered optimal for sleep. Additionally, in the night mode, a timer can be provided that turns off the air conditioner after 7-8 hours.

— Emergency heating. A function found in air conditioners with heating (see "Operating modes"); is intended mainly for summer cottages and other similar places that can be left unattended for a long time during the cold season. When using standby heating, the air conditioner maintains a low positive temperature in the room (about +8..10 °С). It is enough to avoid freezing of walls and damage to communications, and at the same time, energy consumption is low.

— Self-cleaning. The mode of automatic cleaning of the internal parts of the air conditioner — usually due to intensive purging with air. It allows you to remove the accumulated dust inside and dry out excess moisture and also prevents the growth of harmful microorganisms. At the same time, self-cleaning does not eliminate the need for full manual cleaning or replacement of working elements in the air conditioner filters.

Additional features provided by the device.

— Inverter control. The presence of a compressor with inverter power control in the air conditioner. Models without an inverter have only two modes of operation — full power and off, and the set intensity of heating/cooling is provided by turning the compressor on and off for certain periods. In turn, the principle of inverter control is to smoothly change the compressor power, which avoids constant switching on and off. It provides several advantages: minimal wear, no power surges and unnecessary load on the mains, as well as a comfortable (low and stable) noise level. The main disadvantage of inverter models is the rather high cost.

— Timer. A function that allows you to set the time for automatic shutdown of the air conditioner. Thanks to the timer, you can, for example, start the air conditioner before going to bed and fall asleep peacefully without worrying about turning off the device — it will turn itself off after a user-defined time. And in some models, the timer is part of the night mode (see below).

— Auto restart. Automatic restoration of air conditioner settings after a power outage. Simply put, when power is restored, a device with this function will continue to operate in the same mode as before the power outage.

— Air pollution sensor. A sens...or that monitors the presence of smoke, dust and other contaminants in the air passing through the air conditioner. The use of such a sensor can be different: some models can independently start the ventilation mode when pollution is detected, in others the sensor is only responsible for automatic shutdown, and ventilation must be turned on manually. However, this function greatly facilitates the monitoring of air quality.

— Motion sensor. A sensor that monitors the presence of people in the room. Using the location of people in the room, the air conditioner can change the direction of the flow away from people, thereby protecting against drafts. If the presence of people is not detected, then the air conditioner may switch to low power consumption mode and work not at full capacity, maintaining a comfortable temperature, and depending on the implementation of this functionality, it may even turn off if there is no activity in the room for a long time. It helps to save energy and provides an additional guarantee in case the user forgets to turn off the air conditioner manually.

— Vertical blinds drive. Recall that in most models the air outlet has the form of a slot, equipped with two types of blinds — horizontal (usually one), along the length, and vertical, along the height. By default, the motor drive has only a horizontal blind: this allows you to change the direction of the airflow vertically, as well as close the duct during non-working hours. However, some modern air conditioners (mostly wall-mounted, see "Installation") also provide a vertical blinds drive — it allows you to turn them from side to side, changing the direction of the horizontal airflow. It significantly expands the possibilities for setting up the unit for the specifics of the situation.

— Self-diagnosis. The ability to automatically detect malfunctions and errors in the operation of the air conditioner. The specific features of the operation of this function may be different: in some models, the “health” of the unit is constantly monitored or automatically checked at certain intervals, in others, such a procedure is only started manually. Usually, self-diagnostic systems can automatically fix minor problems that do not require external intervention. More serious problems are reported to the user by the device, for example, by an error code on the display.

— Control via smartphone. The ability to remotely control the air conditioner from a smartphone or other similar device, such as a tablet. Usually, for this, you need to install a special application on the device. Such control can be more convenient and intuitive than using the remote control — the application can provide various specific parameters and functions that are not available for the remote control (for example, the schedule of work by day of the week). In addition, through the application, you can monitor the operating parameters of the air conditioner in real time — the set temperature, speed, programme, etc. — and receive notifications of problems. And some models with this feature can even be connected to the Internet — and get access to air conditioning control from anywhere in the world where there is access to the World Wide Web. Connection with the control gadget can be carried out via Bluetooth or Wi-Fi, depending on the model. For some devices, this feature may require the use of an external Wi-Fi module (see below).

— Wi-Fi module connect. Such equipment significantly expands the functionality: a Wi-Fi connection can be used to control via a smartphone or even via the Internet, to transfer statistics and other service data to external devices (smartphone, laptop, etc.), for remote diagnostics and troubleshooting, etc. The specific set of capabilities associated with the wireless module should be specified separately; however, this feature is typical mainly for fairly advanced models. Note that modern air conditioners can be equipped with built-in Wi-Fi modules. However, when buying such a model, you have to immediately pay extra for additional communication options, while with a separate Wi-Fi adapter, there is a choice — you can buy it both together with the air conditioner, and separately, later (or even not buy at all if this function turns out to be unnecessary).

— I Feel (remote control with temperature sensor). The presence of a temperature sensor in the complete remote control. Usually, such a remote control also has a separate button, when pressed, the air conditioner measures the temperature at the location of the remote control, that is, near the user. It allows you to more accurately control the microclimate than when using a sensor on the indoor unit — the device estimates the temperature at the user's location, and not at the installation site of the indoor unit.

Power consumption of the air conditioner in cooling and heating mode; for models without a heating mode, only one number is given. This parameter should not be confused with the effective capacity of the air conditioner. Effective capacity is the amount of heat that the unit can "pump" into the environment or the room. This item also indicates the amount of electricity consumed by the device from the network.

In all air conditioners, the power consumption is several times lower than the effective capacity. It is due to the peculiarities of the operation of such units. At the same time, devices with the same efficiency may differ in power consumption. In such cases, the more economical models usually cost more, but with continued use, the difference can quickly pay off with less electricity consumption.

Also, two points related to electrical engineering depend on this nuance. Firstly, power consumption affects power requirements: models up to 3 – 3.5 kW can be connected to a regular outlet, while higher power consumption requires a three-phase connection (see below). Secondly, the power consumption is needed to calculate the load on the mains and the necessary parameters of additional equipment: stabilizers, emergency generators, uninterruptible power supplies, etc.

The heat output of the air conditioner when operating in cooling mode, in other words, the amount of heat energy that the unit can transfer from the room to the external environment when operating in this mode.

In general, cooling capacityup to 2 kW for modern air conditioners is considered very modest, 2–3 kW is low, 3–4 kW is medium, 4–6 kW is above average, and in the heaviest and most productive models this figure can be 6–8 kW and even more. Also, the conventional unit BTU can be used to denote capacity; in our catalogue, 1 BTU corresponds approximately to 0.293 W, however, for the convenience of choice, some deviations are allowed: for example, the 7000 BTU category includes units with power from 1.8 to 2.3 kW. Also on sale you can find air conditioners for 9000, 12000, 18000, 24000 BTU and more.

As for the choice for this indicator, the simplest formula is as follows: at least 100 W or 1/3 BTU of thermal power should fall on 1 m2 of the area of the room. Thus, to estimate the maximum area served, the power in watts should be divided by 100, and the power in...BTU should be multiplied by three. However, all these calculations are relevant only for standard residential/office premises with a ceiling height of about 2.5-3 m. For other conditions, you need to use a more complex formula, which is the sum of three parameters: 1) Q1 - the heat gain of the room itself, calculated by multiplying the area of the room by the height of the ceilings and the heat transfer coefficient (it ranges from 30 to 40 W, depending on the conditions); 2) Q2 - heat gain from operating equipment (on average, a third of the total power of all electrical appliances); 3) Q3 - heat gain from each person (from 100 W for sedentary work to 300 W for heavy physical exertion). More detailed recommendations regarding such calculations can be found in special sources.

A special case is represented by separately sold outdoor units of air conditioners (see "In box"). In this case, the capacity in cooling mode is the highest heating capacity of the indoor unit (in the same mode, of course) that can be connected to this outdoor unit. For multi split systems, respectively, the total indicator of all indoor units is taken into account.

The power provided by the air conditioner in heating mode. It is indicated by the amount of thermal energy that the air conditioner can "pump" from the external environment into the room when operating in this mode. The most modest modern units have a heating capacity of 2 – 3 kW or even less, in the most performant it reaches 6 – 8 kW or more.

When evaluating this capacity, the same formulas are relevant that are used in calculating the power of traditional heating. So, for the full heating of an ordinary residential or office space (with ceilings of 2.5-3 m and normal thermal insulation), a thermal power of at least 100 W is required. There are more detailed calculation rules that allow you to calculate the necessary characteristics for other conditions. And if we are talking about a separately sold outdoor unit (see "In box"), then the meaning of this parameter is somewhat different. It indicates the maximum power of the indoor unit that can be connected to this outdoor unit to work in heating mode. For multi split systems, respectively, the total capacity of all indoor units is taken into account.

Recall that most air conditioners are not designed for use as full-fledged heating systems. However, such a unit can be a good addition to the main heating system. At the same time, air conditioners are less expensive than el...ectric heaters: the heater has an effective power equal to energy consumption, and the air conditioner consumes much less energy than it supplies to the heated room.

Also note that the unit BTU (more precisely, BTU/hour) can also be used to indicate the effective capacity (including in heating mode). 1 BTU (BTU/h) initially corresponds to 0.293 W, and the numbers in the characteristics of air conditioners correspond to thousands of BTU/h. For example, a 7 BTU air conditioner will produce an effective capacity of 7000 BTU/h, or about 2 kW. Such marking is convenient because BTU can easily determine the recommended area of a standard room (in m2): just multiply the figure indicated in the characteristics by 3. So, in our example, the power of 7 BTU will correspond to an area of 7*3=21 m2.

The amount of air that an air conditioner can pass through itself in an hour.

This parameter depends on the power and the overall level of the device, but there is no strict dependence here: models with the same effective capacity may differ in air circulation speed. In such cases, it is worth proceeding from the fact that a higher speed contributes to uniform cooling/heating of the air and reduces the time required to create a given microclimate; on the other hand, higher-performing air conditioners use more energy, are larger and/or cost more.

The maximum and minimum level of noise produced by the air conditioner during operation; for split and multi split systems (see "Type"), by default, it is indicated for the indoor unit, and the data for the outdoor unit can be specified in the notes.

The noise level is indicated in decibels; this is a non-linear unit, so it is easiest to evaluate this parameter using comparative tables — they can be found in special sources. Here we note that, according to sanitary standards, the maximum level of constant noise for residential premises is 40 dB during the day and 30 dB at night; for offices, this figure is 50 dB, and in industrial premises higher volume levels may be allowed. So it is worth choosing an air conditioner according to this indicator, taking into account where and how it is planned to use it.

As for specific numbers, among the quietest modern air conditioners, there are models with a minimum performance of 23 – 24 dB, 22 – 21 dB, and sometimes even 20 dB or less. However, units at 31 – 31 dB and 33 – 34 dB are not uncommon; such loudness, usually, does not create discomfort in the daytime, but at night it is no longer desirable. However, in some cases, a louder air conditioner may be the best choice: noise reduction affects the cost, sometimes quite noticeably, and if the device...is not planned to be turned on at night, you can not overpay for additional noise reduction.