Abnormal heat in part of the territory of our country has caused the interest in split systems to rise sharply. Now it is perhaps the most frequently discussed equipment for houses and apartments. According to sociological research, 57% of the capital’s residents are going to install such equipment at home. Today we will talk about their little-known variety.— channel air conditioners and features of operation of these devices.

In the “Letter of the Law” section, we have already addressed the topic of air conditioners (see the article “On a Hot Midday, or How to Install an Air Conditioner Legally”, “IVD”, 2010, N 5). This article is devoted to ducted air conditioners, which are gaining popularity. Why is this happening?

Installation of an outdoor unit of a split system of any type on the facade of a building requires mandatory approval.

What is a «duct»?

A split system provides a comfortable temperature and humidity, and also removes odors and dust, but does not maintain an oxygen content sufficient for a living space. In order for the room to feel fresh, atmospheric air must be let in. However, due to the heat and stuffiness, you have to keep the windows closed. You can combine air conditioning with ventilation if you use a channel-type split system. She will first be able to purify the air of poplar fluff and other large particles.

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Y. Filatov, D. Belov, A. Strelkov
Photo by E. Kulibaba A ducted split system consists of two blocks (outdoor and indoor) connected by a pipeline through which the refrigerant moves— carrier of cold or heat. The principle of operation of all split systems is the same. The compressor of the outdoor unit compresses the gaseous refrigerant, which, moving through the radiator blown by the fan, condenses and is sent in liquid form through the copper tube to the indoor unit. Here, the liquefied coolant, passing through the thermostatic valve, evaporates again, passes into a gaseous state, while its temperature drops significantly. The cold gaseous coolant intensively absorbs heat from the air driven by the fan through the heat exchanger. Cooled air through flexible ducts— channels— enters the premises. This is where its name comes from.— «duct».

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GC «Rusclimat»

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1-2. The outdoor unit FGR16H/AG (1) with a large heat exchanger is equipped with two fans and usually works as part of a multi-split system, the MOU-48HR (2) unit with a single fan is more often used in a conventional split system.

3-4. A diffuser built into the false ceiling (3) is used to supply air from the air conditioner to the room, and a decorative grille— for air intake from the room, and it is most often located in the upper part of the wall of the room (4).

The indoor unit cools or heats (if the system has a heat pump mode) the air, cleans it from dust and odors using filters and returns it to the room. The cost of such turnkey systems— about 1800-3300rub. for 1m2 refrigerated area. Duct pipes are supplied to the Russian market by such manufacturers as Daikin, Fujitsu General, Hitachi, Mitsubishi Electric, Mitsubishi Heavy, Panasonic, Sanyo (all— Japan), Dantex (UK), Carrier, York (both— USA), LG Electronics, Samsung Electronics (both— Korea), Electrolux (Sweden), Ballu, Gree, Midea (all— China) andetc. To understand why ducted air conditioners are good for creating a comfortable microclimate and why they need an additional air distribution system, let’s consider the main differences between a “duct” and other types of indoor units.

Three pluses

First advantage channel split system lies in the fact that it is invisible in the interior and reminds of itself only with narrow slots of decorative exhaust grilles and almost imperceptible disks of supply diffusers in the wall or ceiling. ATIn the simplest version, the indoor unit of a ducted air conditioner is a small metal box, on the edges of which there are branch pipes or holes for connecting air ducts and fittings for refrigerant pipes. Its unpretentious appearance does not affect the interior, because it is closed by structures. Inside it is an air filter, a finned heat exchanger, a fan, a drip tray for collecting condensate formed on the heat exchanger, and controls. Some models can be equipped with various complex filters, air heaters, humidifiers, ionizers and automation units (manufacturers offer all this as additional options). A number of devices are assembled according to a modular principle: each functional additional element is made in the form of a separate «brick», and all of them are combined into a single box-shaped structure. The unit, as a rule, is mounted above the false ceiling or in a specially built semi-cornice (a box adjacent to the ceiling along the walls), and the grilles and diffusers are placed in the plane of the false ceiling or in the wall. The indoor unit can also be placed in a vestibule, corridor, hallway or pantry. However, it does not have to be fixed to the wall.— Can be placed on a shelf or on the floor. An air conditioner of this design is suitable for both a city apartment and a country house. Recall that the second, outdoor unit of a split system is always placed outside the living rooms.— on the street (that is, on the outer wall of the house), a balcony or in a technical room, but in such a way that it is well blown by air, since the device generates a lot of heat.

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3D graphics
N. Samarina

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GC «Rusclimat»

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Rice. N. Samarina

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Rice. N. Samarina

5. Layouts of ducted air ducts in residential premises of complex configuration: even two air ducts of different lengths allow using one indoor unit to create a comfortable microclimate in a U-shaped (a) or L-shaped (b), as well as in a narrow (c) room. The diagrams clearly show that the «duct» improves air distribution.

6. Medium-pressure duct block model EACD-55HR (Electrolux) with a maximum air flow of 2500m3/h

7-8. AT“duct” room air can be drawn in from the side (7) or from the bottom of the housing (8).

Expert opinion

Installing a ducted air conditioner is more difficult than a wall-mounted split system. Therefore, you need to carefully choose both the device itself and the specialists who will mount it. An incorrectly selected model can not only not give you the long-awaited coolness, but also cause inconvenience (for example, create increased noise). When purchasing equipment, pay attention to the static pressure of the fan. It determines how branched the duct system can be and how much cold air will reach the consumer as a result. Ducted air conditioners, as a rule, are equipped with the simplest mesh filter that protects the internal structure of the unit, but does not clean the air enough. Therefore, when buying an air conditioner, it is recommended to immediately select an additional filter module with the desired degree of purification. To protect yourself from unexpected troubles with condensate that forms in any air conditioner, look at how the condensate collection pan is made (it must be completely sealed).

Alexander Dubovoy, Product Manager, Rusclimat Group of Companies

Second plus «ducts» in that flexible ducts allow you to improve the direction of the air flow by installing supply diffusers anywhere in the ceiling and adjusting them. In addition to cooling or heating, the air conditioner is able to ventilate the room, purify and humidify the air (if the appropriate modules are available). If you install the device for only one room, it is not necessary to install air ducts: the indoor unit of the ducted air conditioner can supply air to the room directly from the front panel. ATsome devices, such as those included in the FS Multi (Panasonic) range, are specifically provided with the ability to switch the air supply method— via air duct or directly.

The presence of air ducts allows you to supply air to different zones of one room or to several rooms. The benefit is obvious: the “duct” works like a multi-split system, but its simplest version is 2 times cheaper, since it uses only two units (outdoor and indoor), there is no need for additional indoor units, because thanks to the optimal air distribution, a comfortable atmosphere is created everywhere .

However, do not fall into euphoria: the longer the air ducts, the greater the fan power should be compared to other types of indoor unit. ToIn addition, the temperature of the air supplied from one unit to different rooms will be the same, and the requirements for a comfortable temperature in them are different: say, 18 FROM— in the bedroom, 20 FROM— in the living room, 25 FROM— in the nursery. Although such temperature zoning is quite “on the shoulder” of a channel split system. But for this you will have to use a complex system of electromechanical valves that will block the access of air to those rooms where a favorable temperature has already been reached.

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Architect G. Podobulkin Photo by R. Shelomentsev Due to the presence of air ducts, one more indicator of air conditioning operation has to be taken into account— static pressure of the fan. This is the pressure with which the unit can «push» the conditioned air supplied to the room forward when using ductwork. It is usually measured in pascals (Pa). The volume of processed air must be delivered to the appropriate diffusers and then fed into the room through them. According to this indicator, three groups of devices are distinguished: low-pressure (pressure up to 50 Pa), medium-pressure (up to 150 Pa) and high-pressure (up to 300 Pa). Each of them is designed for a certain length and diameter of the air ducts. So, for a high-pressure unit model PEA-RP500GA (Mitsubishi Electric) at a static pressure of 290 Pa, the maximum length of the air duct with a diameter of 150mm is 50m (given that the air flow rate is not lower than 1.5m/s). You can, of course, install an air duct even longer, but the speed of the air flow will decrease so much that the final effect will be comparable to the movement of a cold wave seeping out of the open door of the refrigerator. ATIn any case, it is necessary to choose the dimensions and capacity of the air duct, and to coordinate the static pressure with its length and cross section. However, it should be noted: the higher the air velocity, the higher the noise level. Therefore, at high speeds (5m / s and above) it is necessary to soundproof the air ducts or even install silencers, as on the exhaust pipe of a car.

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LG Electronics

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LG Electronics

9. The indoor unit of the FGR16H/AG (Gree) ducted air conditioner contains a built-in electric heater.

10-11. Channel internal block of the B60LH (LG) model and the drainage pump which is built in it for pumping out of condensate from the pallet.

Typically, consumers choose household split systems with ducted indoor units with a capacity of up to 12 kW (or up to 25 kW). This is enough to maintain a comfortable temperature in a country house with an area of ​​200-300m2 or a three- or four-room city apartment. The air intake at the channel unit can take place both from below and from the side, while the filter for cleaning the air from dust and odors is installed accordingly. When working without air ducts, some models are provided with dampers that swing automatically (Autoswing), changing the direction of the air flow horizontally from left to right or right to left. They can also be locked into one of five angle positions.

Third plus «ducts» is that they allow you to simultaneously air-condition and ventilate the room due to the additional installation of a kit for mixing fresh air. ATIn this case, fresh air from the street is supplied through a heat-insulated duct to a mixing chamber built into the indoor unit or attached to it as an additional unit. There it combines with the air taken from the room (i.e. recirculated). The air mixture is filtered and processed in the indoor unit depending on the specified thermal regime (cooling or heating). The ratio of supply air to recirculated air is usually regulated depending on the season and is a maximum of 25-30%, but most often 8-15%. If you use «ducts» all year round in regions with a cold climate, you will have to provide a duct heater with a thermostat and reduce the volume of supply air in winter so that this heater has time to warm up the volume of cold street air before mixing. ATIn this case, we can talk about creating a climate control unit with a common IR remote control that allows you to change the fan speed. But the air mixing system increases the installation cost by almost 2 times.

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Mitsubishi Electric

12. Scheme of the channel section of a split system with fresh air admixture.

13. Layout of the main elements in the fresh air mixing channel up to the mixing chamber.

14. Scheme of a VAV system based on the PEFY-P63VMA model (Mitsubishi Electric) for a two-room apartment. The air is distributed throughout the rooms, bathroom and kitchen.

Expert opinion

The rooms are often not only hot, but stuffy. Therefore, it is not enough to lower the temperature to create a comfortable atmosphere. The freshness of the air depends on the content of positively and negatively charged oxygen ions (aeroions) in it, which affect the well-being of a person. It is important to supply fresh air to the rooms. Split systems of duct and cassette types allow you to create an influx of fresh air and at the same time ensure air recirculation in the room. It can be organized in two ways, depending on the design features of the indoor unit. So, in the Gree «ducts» with a capacity of up to 16 kW, the air supplied from the street and the recirculated air are mixed in the indoor unit. The second method is associated with an additional mixing chamber, which is mounted in front of the «duct». Toit is connected to the supply air ducts of the air conditioner and the fresh air supply duct, as, for example, in the FGR20H / AG (Gree) model. ATIn any case, a cleaning filter and a motorized valve to regulate the air supply must be installed in the fresh air intake duct. An additional electric heater in this duct can be installed if the air conditioner is used in the cold season.

Vladimir Sviridov, technical specialist at Euroclimate

Despite all the advantages of «ducts», they have one drawback: with sub-ceiling installation, the ceiling height in the room will decrease by at least 250mm.

How to mix fresh air?

Atmospheric air enters through a protective grille at the end of the air duct, led through the wall to the street. Behind it, a mechanical air filter is installed. After the filter, you can mount a duct heater with a thermostat to periodically heat up too cold outdoor air. The power of the heater fluctuates in the range of 1.5-4 kW, depending on the serviced area and the difference in air temperatures (atmospheric and indoors). To increase the pressure of the supplied atmospheric air, a supply fan is often mounted in front of the heater.

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N. Samarina

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15. The plan shows the location of the air ducts in a two-room apartment with an area of ​​​​112m2
when using a channel split system with a cooling capacity of 12 kW and a static air pressure of 120 Pa.

16-17. Medium-pressure indoor unit model S-F50DD2E5 (a) and low-pressure model S-56NA1E5 (b) from Panasonic.

18. Low pressure indoor unit FDXS model (Daikin) is quite small— total 200mm.

Air mixing is «managed» by a controller installed inside the kit. It gives the command to turn the supply fan on or off. An electronic board and a thermistor located in the air duct behind the filter control the temperature of the supplied atmospheric air, periodically changing the power of the duct heater. ATthe air duct through which fresh air enters is provided with an electrovalve (it does not allow cold air to enter the room when the system is turned off) and a filter for cleaning the supply air.

Some manufacturers offer a ready-made kit for mixing atmospheric air. It is designed for ceiling duct and cassette indoor units.

The percentage of mixed volumes is not regulated and depends on the air temperature in them, as well as on atmospheric pressure. However, using a single channel air conditioner, you can solve the problem of ventilation and air conditioning of the home. The main thing is that the specialist of the company in which you buy this equipment correctly calculates the future air exchange, including the distribution of air supply diffusers to each room and between them; picked up the performance of the split system and static pressure, providing sufficient pressure; foresaw an electric or water heater to heat the atmospheric air in the cold season. Andfinally, it is necessary to correctly mount the «duct» in order to save space and not lose performance.

Air distribution with VAV system

Recently, in the practice of building country houses, automatic systems for zonal air flow control are increasingly used.— the so-called VAV systems (Variable Air Volume). They allow you to create a multi-zone system based on a «duct» with high performance (25 kW or more). In order to synchronize the operation of the indoor unit fan with the system of controlled dampers, two special connectors can be provided on its electronic board (see diagram on page XX). The first of them receives an external analog signal from the controller of the zonal air flow control system, which controls the speed of the “duct” fan. The second connector receives an external digital signal that starts and stops the system, and also switches the operating modes (heating or cooling). The compressor capacity of the outdoor unit of the system will automatically change according to the air flow of the indoor unit.

Expert opinion

The condensate drain pump can be built into the duct air conditioner housing (factory equipment) or installed outside it additionally. ATIn the first case, it is a component of a single climate control equipment. Therefore, if the pump fails, an emergency stop of the air conditioner will occur, which will help prevent condensate from leaking to the ceiling and walls. The noise level of a running drain pump is significantly lower than that of a functioning fan of a ducted air conditioner. There is only one drawback: if you need to raise the condensate above the outlet fitting, such a pump can only do this up to a height of 40-50cm, and then the liquid will drain by gravity through the drain pipe to the street or into the sewer (through a water seal). An autonomous drainage pump (pump) is able to raise condensate by 8-10m or pump it horizontally by 20m. If necessary, you can install several of these pumps in series (for example, every 8m lift or after 20m of horizontal area). However, during installation, autonomous soundproofing of the pump is required. ATduring operation, the pump will have to be cleaned at least 2 times a year, and for this you need to provide convenient access to it. Finally, if it fails, the air conditioner will not stop working, and condensation may leak as a result. ATIn this case, it is necessary to provide an electronic circuit for an emergency stop caused by this cause.

Pavel Mazilin, Chief Engineer of Trade House «White Guard»

Since the VAV system controller provides a smooth change of the damper position, the air flow in the indoor unit is regulated by maintaining a constant static pressure at its outlet. The differential pressure transducer generates a control analog signal, which is fed to the first connector of the control board. This signal will maintain a constant static pressure in the duct regardless of the position of the dampers. If all of them are closed at the same time, the interface unit will immediately turn off the air conditioner.

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«White Guard»

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«White Guard»

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«White Guard»

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19-21. Stages of installation of the «duct» Dantex: connecting the unit with air ducts and fixing the entire structure to the main ceiling (19); installation of service hatches in the ceiling (20); installation of air intake grilles in the wall of the room (21).

22. Ranges of achievable indoor temperature depending on the outdoor temperature: in cooling mode (a), in heating mode (b).

Features of the installation of the «duct»

Flexible air ducts with a diameter of most often 150 are attached to the protruding nozzles of the kit.mm. It is desirable that there is a service hatch near the place of their connection in the ceiling for free access to the air duct. It must be ensured that there are no bends or twists along the entire length of the flexible duct— because of them, the cross-sectional area is significantly reduced and aerodynamic resistance increases. ATthe place where the supply air duct is attached to the wall on the outside of the building, a protective cover is provided.

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N. Eliseeva
A photo
R. Shelomentseva If it is necessary to separately regulate the temperature in different rooms, it will be necessary to install dampers with electric drives in the air ducts, and in all rooms where it is required to independently control the temperature,— thermostats. BUTif the temperature can be the same everywhere, a ducted air conditioner will cost about 50% cheaper than a multi-split system and 3 times cheaper than a multi-zone unit such as VRF or VRV. It will also be possible to save if you install, for example, two channel split systems, one of which serves rooms with windows facing north, northwest and northeast, and the other— with windows to the south.ATIn this case, during the off-season, the first of them will often work in heating mode, and the second— in cooling mode. If you install a high-level group controller, you can individually set different operation modes for several indoor units at once (up to 16).

The choice of «duct» for a city apartment

To ensure uniform air circulation in residential premises, it is necessary to correctly position the supply and exhaust grilles and diffusers, choose the right length of air ducts, calculate the required air flow and air conditioner performance. So, for air conditioning of residential premises of a two-room city apartment with a total area of ​​112m2 with a kitchen, an entrance hall, a bathroom and a toilet, an FGR-12 (Gree) channel split system was used with a cooling capacity of 12 kW, a heating capacity of 13 kW and a static air pressure of 120 Pa. Exhaust grilles and adjustable supply diffusers are installed in every room and kitchen. The «duct» is mounted behind a false ceiling in the hall. At the same time, it was also necessary to arrange a hemmed ceiling in the toilet and a semi-hemmed— along one wall in the kitchen (for installation of air ducts). Air is supplied and taken in through heat and sound insulated air ducts with an outer diameter of 250 and 315mm. The total length of the supply air ducts is 10m, exhaust— 5.2m. An electric air heater with a capacity of 3.6 kW is installed in the indoor unit, which is connected in the off-season. Split system noise level— 35dBA. Later, after the installation of additional ventilation ducts, an air heater, a duct fan, a filter and automation, outside air was added to this air conditioning system, and this is also carried out in winter.

Some characteristics of channel split systems of various manufacturers

Indicators MHA 60HR (Midea) MHA 60HR (Ballu) EACD55HR (Electrolux) FGR Series (Gree) S-F50DD2E5 (Panasonic) B60LH (LG Electronics) 60KHM2N (Dantex)
Productivity, kW Up to 17.6 Up to 17.6 Up to 16.2 5 to 40 Up to 15 Up to 16.4 Up to 17.6
Maximum static head, Pa 292 292 120 80 to 150 98 98 192
Maximum air flow,m3/h 2900 2900 2500 840-5500 2700 2400 31 500
block height,mm 380 380 370 266-650 360 From 260 From 210
Minimum noise level, dBA 49 49 From 49 44-60 45 49 34
Heating mode There is There is There is There is There is There is There is
Number of other modes 6 6 6 6 6 6 6
Number of fan speeds 3 3 3 four 3 3 3
Air mixing There is There is There is There is There is There is There is
Self-diagnosis mode There is There is There is There is There is There is There is
Integrated drain pump Not Not Not Not Not There is Not


Maintenance of duct indoor units is more difficult than maintenance of other types of air conditioner indoor units. It is better to entrust this to a service center specialist. When the air is cooled, condensate is released, which flows into a tray specially provided for this purpose, located in the duct block. From there, the condensate leaves by gravity or is periodically pumped out by a drainage pump through a pipeline outside the room, but dirt gradually accumulates at the bottom of the pan. Therefore, the pallet will have to be washed periodically. The drainage pump is supplied and mounted separately from the unit, but it can also be built-in (the second option, of course, is more convenient). Through the service hatch provided during the installation of the air conditioner, the owner will be able to independently control the condition of the air filter and the drainage pan, as well as wash them. By the way, installers do not need to be reminded to embed such a hatch when installing an air conditioner,— they themselves will offer this service. ATRecently, equipment has appeared, for example, from the FS Multi (Panasonic) model range, with a filter contamination indicator, which will save you from periodic checks of this device and tell you when it should be replaced.

Expert opinion

The user’s manual for each model lists the allowable outdoor and indoor air temperature ranges for cooling and heating operation. They define the boundaries beyond which the operation of the air conditioner is ineffective or even dangerous, since it is fraught with accidents. When selecting equipment, check that the temperature ranges match your operating conditions. ATin cooling mode, the operating temperature of the outdoor air (more precisely, the temperature of the air cooling the outdoor unit) must have both an upper and a lower limit, due to the characteristics of the refrigeration cycle of the device and its design. Upper limit (43-46 C) determines the maximum allowable operating pressure in the system. It cannot be exceeded because the protection system will stop the air conditioner in an emergency. So, if the outdoor unit is located in the sun and air access to it is difficult, this may cause the air conditioner to stop. Manufacturers produce equipment with a lower working limit of outdoor air temperature of about 10 C, designed for residential areas in which little heat is generated from appliances and people, as well as with an extended range up to -10 and even -15 C. When buying a model, check these values. A wider range affects the cost of the device. The range of permissible operating air temperatures in the room characterizes the ability of the air conditioner to adapt to variable thermal loads and maintain comfortable parameters of air from the street. Equipment with a lower temperature limit (wet bulb) 14 C and below can be considered excellent: it will maintain comfortable parameters both in the heat and in the off-season. ATheating mode upper limit of outdoor temperature approx. 20 Suits everyone. Atthe simplest models, the lower limit of the outdoor temperature is about -5 C. These air conditioners function successfully in the off-season. Equipment with operating temperature up to -15…-20 C claims to be used as an air conditioner in the southern regions all year round. It is possible to achieve lower operating temperatures, but this will make the equipment much more expensive, and is also associated with low energy efficiency in severe frosts. Therefore, such devices — a rarity. Comfortable room temperature range — 15-27 S. Vheating mode operation is possible at room temperatures of 10 C and above.

Anatoly Stein, Candidate of Technical Sciences, Head of the Daichi Training Center

Maintenance is simplified if the model has a self-diagnostic mode. When it is activated, the correct operation of the air conditioner is automatically checked, and if an error is detected, its code is displayed. Knowing it, you can call the service center, where they will tell you what to do.

The material was prepared based on the results of a survey of readers on the website of the action «Create new ideas»

The editors would like to thank the Rusclimat Group of Companies, as well as the representative offices of Mitsubishi Electric, Panasonic and LG Electronics for their help in preparing the material.

  • Source: Ideas for Your Home Magazine#145


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