How to choose an air conditioner

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In this Article: History of Creation; what refrigerant is used in air conditioners; how the air conditioner works and works; operating modes of split systems and air conditioners; types of household air conditioners, their pros and cons; recommendations for choosing an air conditioner.

Air conditioners

The summer season has many advantages and one major disadvantage is the heat, which causes increased sweating and requires large amounts of water to cool the body. There are two effective ways to cope with the summer heat: submerging your body in water and thereby lowering its internal temperature; purchase climatic equipment for air conditioning and bring the atmosphere in the room to a more comfortable one. Since the first method, unfortunately, is extremely rare for us, we will take a closer look at the second method and try to figure out what an air conditioner is and how to choose it correctly for your needs..

History of the air conditioner

The first experiment to rapidly cool objects to low temperatures was carried out by Benjamin Franklin and chemist John Hadley in 1758. They tried to change the readings of a mercury thermometer using rapidly evaporating liquids – ether and alcohol. Franklin and Hadley managed to change the thermometer reading to -13 ° C, and in the room where the experiment was carried out, the temperature was +18 ° C.

However, the principle of operation of modern refrigeration units was discovered only in 1820 – the English scientist Michael Faraday, during experiments on freezing and heating ammonia, found that when it was brought to a liquid state and actively evaporated, air was cooled. So, the principle of operation of a refrigeration device, in which the refrigerant evaporates with the absorption of heat and, when it returns to a liquid state, releases this absorbed heat back, was practically discovered by Faraday.

Michael Faraday
Michael Faraday (September 22, 1791 – August 25, 1867)

But the inventors of those times tried hard to organize air conditioning on the melting ice. The first and relatively effective way to cool indoor air was invented by the doctor John Gorrie in an attempt to somehow reduce the suffering of patients with malaria and yellow fever at his hospital in the town of Apalachicola (Florida, USA). He invented and built an ice-generating machine and hoped that his invention would become popular, although his icemaker worked with frequent interruptions and leaks. However, his invention did not become so popular..

In 1851, a mechanical ice maker equipped with a compressor was invented by the Englishman James Harrison – his invention produced 3,000 kg of ice per day. Encouraged by Harrison, he tried to implement the installation on ships loaded with beef, but experimental transportation of frozen meat in chambers with ice produced by Harris’s icemaker failed – the ice melted faster than the generator could produce its new batch and the batch of beef had to be thrown overboard.

The first truly efficient air conditioning unit was created by the inventor engineer Willis Carrier in 1902, commissioned by the Sackett-Wilhelms printing company.

When creating the installation, Carrier used his knowledge in the field of steam heating – he passed the air from the compressor into the pipes, into which he installed spiral coils with cold water circulating through them. The air conditioning unit, invented by Willis Carrier, allowed not only to cool the air in rooms, but also did not increase the level of humidity in them, which was important for printing equipment and paper, and the efficiency of the factory employees increased significantly. It is Willis Carrier, the founder of the ventilation systems company Carrier Corporation, who is recognized worldwide as the creator of the first air conditioning unit. By the way, it was Carrier’s company that first launched the production of household (room) air conditioners – it happened in 1929.

Stuart Kramer
Stuart Kramer. (1868 – 1940)

But the authorship of the common term “air conditioner” belongs to the American Stuart Kramer, who in 1906 was engaged in research on increasing air humidity in the shops of a textile factory in Charlotte (North Carolina, USA). In a patent application for an installation that evaporates water while increasing air humidity and simultaneously cooling it, Kramer called his invention an air conditioner. The sonorous and attractive term was immediately picked up by Willis Carrier, adding it to his company name..

The refrigerant problem remained – ammonia, propane, chloromethane and sulfur dioxide, which performed this task in the first air conditioners, were poisonous and explosive, air conditioner manufacturers were forced to separate air conditioning units into two split units and remove the refrigerant unit as far as possible from the premises where they were located. people. That all changed in 1928, when American chemical engineer Thomas Midgley Jr. and chemical scientist Albert Henne synthesized the refrigerant dichlorofluoromethane, which they called Freon. Freon was non-flammable and explosion-proof, did not cause poisoning in the event of a leak – thanks to its properties, it became possible to produce a monoblock window air conditioner, similar to the Soviet “BK”.

The first window air conditioners, in 1929, were put on the market by General Electric, although they were still extremely dangerous – the refrigerant in them was ammonia. After replacing ammonia with freon in 1931, the production of window air conditioners was picked up by several American companies at once, their popularity increased sharply.

25 years ago, environmental scientists found out that the refrigerant freon causes colossal harm to the ozone layer of the Earth..

However, by the middle of the 20th century, Americans had lost their leadership in the field of domestic and industrial air conditioning units – Japanese companies began to lead, offering cheaper and higher quality air conditioners that surpassed their American counterparts in their characteristics. In 1958 the Japanese manufacturer Daikin released the first air conditioner capable of not only cooling, but also heating indoor air. In 1961, Toshiba made a splash on the air conditioning market by reviving the production of split systems from two units – a unit with a noisy compressor was mounted outside the premises, and such a split could be installed anywhere, not just where there is a window. The first multi-split system, in which there was one outdoor unit with a compressor and several indoor air conditioning units, was again developed by the Japanese “Daikin” – in 1969.

By the way, the Soviet air conditioner with the unassuming name “household air conditioner” or “BK”, the production of which was launched in Baku (Azerbaijan) in 1975, was created together with Japanese engineers from the Hitachi company. It was noisy, bulky, energy-intensive and fabulously expensive, but there were no other options for the citizens of the USSR to defeat the summer heat in their homes..

Soviet air conditioner BK-1500
Soviet air conditioner BK-1500

The prototypes of all modern split systems and air conditioners were created in Japan: 1977 – air conditioner with a microprocessor (Toshiba company); 1981 – an inverter air conditioner capable of independently lowering and increasing the operating frequency of the compressor, which significantly reduced energy consumption (Toshiba company); 1982 VRV or Variable Refrigerant Refrigerant Circuit (Daikin).

25 years ago, environmental scientists found out that the refrigerant freon causes colossal harm to the ozone layer of the Earth. According to the results of environmental studies, the Montreal Protocol was adopted, according to which the world’s leading producing countries are obliged to completely stop using freon (R-12) by 2014, replacing it with safer 1,1,1,2-tetrafluoroethane (R-134a).

The device and principle of operation of the air conditioner

Regardless of the number of units, any air conditioners, excluding the case, consist of the following elements:

  • a compressor that compresses and drives the refrigerant through the pipes of the refrigeration circuit;
  • a condenser, outwardly reminiscent of a radiator, is always discharged outside (outside the room), converting the refrigerant from a gaseous state to a liquid;
  • an evaporator, also similar in design to a radiator, located in the inner or, in the case of a monoblock, the air conditioner section facing the room. Converts refrigerant from liquid to gaseous state;
  • a throttle (thermoregulation valve) or a coiled capillary tube that reduces the pressure of the refrigerant in the circuit before entering the evaporator;
  • fans, the rotation of which increases the rate of heat exchange between the condenser and the evaporator with the external air.

In addition to the main elements, a modern air conditioner is equipped with a temperature sensor, electronic control and air filters.

How to choose an air conditioner
1 – compressor, 2 – four-way valve, 3 – electronic control circuit, 4 – external fan, 5 – condenser, 6 – refrigerant circulates through these pipes, 7 – internal fan, 8 – evaporator, 9 – coarse filter (preliminary), 10 – fine filter.

Now about how the air conditioner works. All its elements described above, with the exception of the fans, are interconnected by copper or aluminum tubes with thin walls. A closed refrigeration circuit is formed, containing refrigerant and some compressor oil.

Cooling mode. When the air conditioner is turned on, the refrigerant begins to flow from the evaporator into the compressor in the form of a gas having a temperature of 10 to 20 ° C and under a pressure of three to five atmospheres. In the compressor, the refrigerant is compressed, its pressure increases from 15 to 25 atmospheres, it heats up to a temperature of 70 to 90 ° C and enters the condenser through the circuit pipes. The heating of the condenser, where the refrigerant enters, is reduced by intensive operation of the fans. Cooling down, the refrigerant turns into a liquid state, its temperature is higher than the external atmosphere – about 10-20 ° C, the pressure is quite high.

At the outlet of the condenser, the refrigerant enters the capillary tube or thermoregulation valve, the temperature and pressure decrease, and it partially turns into a gaseous state. This mixture of gaseous and liquid refrigerant, under low pressure, is introduced into the evaporator. In it, the liquid part of the refrigerant completely becomes a gas, while heat from the outside is actively absorbed – the air pumped in by the air conditioner and passed through the evaporator becomes cold. After the refrigerant in a gaseous state and under low pressure enters the compressor again – the process starts from the beginning.

Heating mode (heat pump) or reverse. Almost all models and brands of modern split systems are able not only to condition (cool) the air in the room, but also to heat it by supplying hot air. To perform this function, the air conditioner is equipped with a special valve – a four-way valve, capable of changing the direction of refrigerant flow from the compressor in the forward or reverse direction under the control of a solenoid. The principle of heating is similar to the principle of the cooling mode – the difference is that the refrigerant goes through the stages of high, low pressure, rising and falling temperatures in a cycle opposite to the cooling cycle. Those. the condenser of the external (outdoor) unit of the split system is cooled, and the evaporator of the indoor unit heats up, giving off heat to the air blown by the fans into the room.

Ventilation mode in split systems.In this mode, the compressor is turned off, the movement of the refrigerant in the system is completely stopped – the indoor unit of the split system mixes the air inside the room using fans. This will allow, for example, to more efficiently distribute warm air coming from heating batteries, move it with cold air – i.e. create a homogeneous indoor temperature climate.

Dehumidification mode.When the evaporator cools down, moisture contained in the room’s atmosphere condenses on its metal body – it accumulates in the pan. Working in the cooling mode, the air conditioner accumulates and drains condensate from the pallet automatically: in split systems through a plastic tube brought from the indoor (indoor) unit to the sewer system or outside; in monoblock (window) air conditioners, moisture is discharged through a metal tube, the outlet of which is located on the bottom on their outer (street) side.

Types of household air conditioners

Among the many different air conditioners, only four are fully household: window (monoblock), mobile, wall monoblock, split system and hybrid air conditioner.

Monoblock conditionersoutwardly similar to Soviet BC, only they have smaller dimensions and are distinguished by high quality characteristics – they are less noisy, often they are able not only to cool, but also to heat the room.

Types of household air conditioners

Their positive characteristics: low cost – from 7,000 rubles; air conditioning, purification and introduction of fresh air into the premises from the street; easy installation into a window frame or into a prepared hole arranged in a thin wall, no need for installers with special equipment.

Negative characteristics: low productivity, sufficient only for one small room; installation in plastic or aluminum window structures with double-glazed windows is permissible only if it was assumed in advance, even at the stage of ordering the frame, and it has a prepared opening for the size of the air conditioner.

Mobile air conditionerby design, it is no different from a window monoblock, only it is equipped with a wheelbase and is not installed permanently. To remove hot air, the mobile air conditioner has a flexible hose with a fastener that allows it to be fixed in a slightly open window.

Types of household air conditioners

Positive characteristics of the mobile air conditioner: does not require installation; easily move from one room to another; not expensive – the cost is from 10,000 rubles.

Negative characteristics: low power – it is enough for only one room; unprepared air from the outside will flow through the slightly open window; heating or cooling without bringing in fresh air from outside; requires manual condensate removal.

Wall-mounted monoblock.Externally, it is similar to the internal block of the split system and is also mounted on the wall. Its positive and negative characteristics are similar to those of a mobile air conditioner, it costs from 16,000 rubles, during operation it is more noisy than a split-system unit. The main advantage is the location, i.e. will not get underfoot.

Split system. Today split systems are the most popular and widespread device for maintaining an acceptable indoor climate. There are a large number of manufacturers and brands of split systems, divided into “economy”, “middle class” and “elite”. Separately, it is worth noting inverter-type split systems – they are equipped with a system capable of maintaining the temperature at a strictly specified level without drops, by lowering and increasing the compressor speed. The compressors of conventional air conditioners operate at the same speed, switching off when the set temperature in the room is reached and turning on again when it rises or falls, depending on the operating mode (cooling or heating). At the same time, people in the room will periodically feel uncomfortable due to temperature changes, and the power consumption will be high. The inverter air conditioner does not turn off at all – by changing the speed of the compressor, its temperature sensors set the operating mode that allows you to maintain the temperature set by the user. At the same time, electricity consumption is reduced, because the air conditioner operates most of the time with less power, there is no high energy consumption with frequent compressor starts.

Types of household air conditioners

Positive characteristics: low noise level, because the unit with a noisy compressor is outside the building; air purification from dust suspended in it; more efficient than any monoblocks, even with the same power; installation on any of the walls is allowed; economical power consumption, especially in inverter split systems; in multisplit systems, only one external, but rather powerful unit is required, with several internal ones, i.e. the facade of the building will not be hung with external blocks.

Negative characteristics: high, in comparison with monoblocks, cost – economy class from 20,000 rubles; the need for specialized installation, with the obligatory involvement of installers; lack of fresh air supply from the outside in any models of split systems, with the exception of the Ururu Sarara series of the Japanese manufacturer Daikin; if the external block of multisplit systems fails, all internal blocks will not work; require mandatory maintenance; most split systems are not able to work at subzero temperatures outside.

Hybrid air conditioner.By design, climatic devices of this type are something in between mobile monoblock air conditioners and split systems – their indoor unit is equipped with wheels and is easy to move, they also have an external unit that can be placed, for example, on a balcony or suspended from a window on belts. The blocks are connected to each other by flexible and durable hoses along which the refrigerant moves.

Positive characteristics: large, in comparison with mobile monoblocks, power – cooling or heating a room up to 60 m2; less noise; do not require professional installation.

Negative characteristics: rather high cost – from 17,000 rubles; it is very difficult to find air conditioners of this type in stores, they are practically not imported; requires periodic removal of condensate from the sump in the indoor unit.

How to choose an air conditioner – recommendations

How to choose an air conditioner

So, let’s go directly to the question of choosing an air conditioner. Before visiting stores and looking for a suitable air conditioner in all respects, you need to find out the following:

  • the actual need for cooling this room to find out the required power of the air conditioner in kilowatts. According to a simplified scheme, it is calculated at the rate of 1 kW for every 10 m2 premises with a ceiling height of no more than 2.7 m. A more accurate calculation is based on the location of the room (sunny or shady side), the number of people present in it, the number of household appliances and lighting fixtures. Only a specialist can carry out such a calculation, therefore we rely on the calculation according to a simplified scheme with rounding to a larger value – by and large, an air conditioner with a capacity of 2.5 kW will be enough for one room;
  • is the electrical network in the house able to withstand an additional load of 2-3 kW. Often, electrical wiring in old buildings is not designed for it, it would be reasonable to lay an independent electrical wiring line for the air conditioner, with the installation of an independent automatic fuse in the electrical panel;
  • will determine the place of installation of the air conditioner, in the case of choosing a split system – the place of installation of the outdoor unit, taking into account the need for its future maintenance, i.e. there must be free access to it. When choosing a place for installing the indoor unit, please note that you should not place it directly above the bed, dining table or work table – it will blow out, there will be health problems.

According to performance and price range, air conditioners from different manufacturers are subdivided like this:

  • class “economy”, it has Korean and Chinese air conditioners brands “LG”, “Midea”, “Dantex”, “Samsung”, “Gree”, “Haier”, etc. The cost of air conditioners from these manufacturers starts from 15,000 rubles, the service life with timely prevention and maintenance is no more than 5 years, after which serious repairs will be required
  • middle class, in which the models of air conditioners of Japanese and European brands “Panasonic”, “Hitachi”, “McQuay”, etc. Air conditioners of these brands cost from 20,000 rubles, the average service life is 7 years;
  • the “elite” class includes equipment from Japanese manufacturers that have been leading the world air conditioner market for decades – Daikin, Fujitsu General, Mitsubishi Haier, etc. Such air conditioners have the largest number of options and capabilities, and not cheap materials and electronic boards are used in their design. Their cost starts from 25,000 rubles, the average service life is 15 years.

General recommendations for choosing an air conditioner for your home are described here, in addition to you will need to find out:

  • what kind of guarantee does the manufacturer of this brand of air conditioner give for its main element – the compressor. In the event of a compressor breakdown, replacing it can cost half the cost of the entire air conditioner;
  • which filters – disposable or reusable – are installed on the internal block of the split system, if disposable, then what is the frequency of their replacement and the cost of new ones;
  • what is the limiting range of “street” temperatures in which the split system will work without interruption, is this air conditioner equipped with a heating system for the outdoor unit at subzero temperatures. If there is no heating system, then the air conditioner cannot be used in winter – it will freeze and fail;
  • the noise level of the indoor unit of the split system, it should not exceed 30 decibels (ideally 25 dB);
  • what accessories are included in the air conditioner kit – for a split system, you will need about 10 m of a copper tube, 5-6 m of a drain pipe, 4-5 m of power cables connecting the outdoor and indoor units (the exact need for the length of the components depends on the installation location and the distance between external and internal units). Does the price include a mounting kit.

The best choice would be an inverter air conditioner that can both cool and heat the room. Please note that the heating function is designed only for the off-season, but not for the winter season – in winter the air conditioner is not used, or is used only in ventilation mode.

Installation with the involvement of specialists in the off-season will cost an amount equal to 20-25% of the cost of the split system; in the warm season, the prices for installing an air conditioner can reach 40% of the cost.

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