Air conditioner with fresh air supply: design and selection of supply split system

In warm and comfortable houses, problems with natural ventilation often arise, and therefore the oxygen content drops sharply.This affects the health and activity of homeowners and enterprise workers.

To solve the problem, forced ventilation is used. A modern air conditioner with fresh air is an example of effective and affordable climate control equipment. We will tell you how the equipment works and how to choose it wisely.

Comparison of conventional and supply air conditioners

A common mistake among users is that they consider any air conditioning system to be a ventilation system. In fact, only some types of equipment can operate in active air exchange mode with street air masses. To make it clearer, let’s first consider the design of a conventional split system.

Air conditioners for domestic use, which are commonly called split systems, are a set of two separate modules that have a different structure from each other and are located in different places.

The first module is an evaporation unit, which is installed on the floor, hung on the wall or partially masked with ceiling cladding. The second module is a remote compressor-condensing device, usually mounted on the facade of a building.

Schematic representation of a device with an internal module mounted on the wall. The two modules are connected to each other by thin copper tubes through which freon moves. The tubes are hidden in grooves behind decorative trim or in plastic boxes (+)

The operating principle of the air conditioner is simple. Through the intake grilles, room air enters the unit, where it is cooled, and then removed through the air ducts to the outside. The change in air temperature is based not on the production of cold, but on the transfer of thermal energy.

The carrier is freon, which enters the remote module in a gaseous state and returns in a liquid state. To enter the gaseous phase, freon takes some of the heat from the exhaust air in the evaporator.

In fact, no replacement of air masses occurs, and cooling (as well as heating and filtration) is carried out by recirculation. The supply equipment is designed differently. An example of a split system with the organization of fresh air flow is a duct-type device.

Design diagram of a ducted air conditioner, which performs the functions of ventilation and temperature control indoors. A mandatory design element is a heater built into the pipe (+)

Of course, ordinary split systems are easy to install, have many additional functions, and have a beautiful modern design, but, unlike supply air systems, they do not refresh the air in the room - and this is their main disadvantage.

What is special about multi-split systems?

Speaking about air conditioners in a general sense, it is necessary to mention multi-split systems, which are also used to equip multi-room apartments, private houses, office and industrial buildings.

They differ from ordinary ones in that they have only one remote block, while there can be several internal ones. The minimum quantity is two modules, the maximum is limited to four. If you use more indoor units, the system will lose its performance and will not operate at full capacity.

The number of pipelines increases, accordingly, the cost of equipment increases and the installation of some parts of the structure becomes more complicated. It is important to create conditions for laying all connecting elements (+)

The multi-split system is not always used, but only in certain cases when the installation of a large number of outdoor units is impossible for a number of reasons:

• the building is a historical or architectural monument;
• there is a ban on installing remote blocks on the facade;
• For hanging equipment, the architecture of the building provides certain places limited in area.

Sometimes the installation of a large number of remote modules is refused for aesthetic reasons: the beautiful facade of the building, hung with oversized buildings, looks unpresentable.

The rules for the improvement of large cities are periodically amended to prohibit the placement of air conditioners on facades facing central streets. The solution is to install the block on the courtyard wall of the building

The advantage of a multi-system is the installation of one remote module, the disadvantages are complex work on installing pipelines, reduced productivity and reliability. In addition, all internal modules must operate in identical modes: either heating or cooling.

Supply duct models

The function of replacing exhaust air masses with air from the street is fully implemented only in ducted air conditioners, so we will analyze their features and performance characteristics in more detail.

A properly designed and installed ducted split system copes with the tasks of ventilation and control of the indoor microclimate.

Distinctive features of an air conditioner with inflow

Recirculation models of duct air conditioners (CC) are similar in operating principle to conventional split systems, but they differ in design and installation location. Internal modules are built into suspended ceiling structures, and air circulates through the channels connecting them to the outdoor unit.

This is what a simple recirculation model looks like, unable to supply fresh air. In order for the system to perform the supply function, a built-in heater is required.This is regulated by SNiP rules, according to which the lower temperature threshold of air masses coming from the street must be +14 °C.

If the air temperature outside is above -15 °C, it copes with the heating function Heat pump. However, at lower temperatures, air conditioner models with water or electric heaters are used. Heating equipment can be either additionally installed or built-in.

The heating system is equipped with an automation unit, thanks to which the fresh air supply is adjusted in different modes, depending on the season. The automatic unit is controlled using a remote control

Programmable air supply systems are more expensive than conventional room modifications with wall installation, but they are much more efficient and functional precisely due to the combination of ventilation and air conditioning. The amount of oxygen in the air meets sanitary requirements, the temperature is easily regulated, and the appearance does not create discomfort, since all the working parts of the system are located in an invisible area, above the ceiling.

Operating principle of the supply system

To transport air from the street to the premises, air ducts are provided, which conventional split systems do not have. First, air from the street moves through the outdoor unit into an insulated channel, then into the mixing chamber. There, the incoming air combines with the exhaust air, refreshing it.

Then the air mixture passes through the filters and, according to the selected mode, is processed. Air masses are dehumidified, heated or cooled. After this, purified, filtered, partially refreshed air at a given temperature enters the premises.

Channel modifications with admixture are used in large rooms that are separated from each other by non-permanent partitions. These are apartments with ceilings of 3 m, clinics, food establishments, sports and educational institutions, offices, etc.

Typically, the temperature maintained depends entirely on the season. In summer, supply duct air conditioners work for cooling, in winter - for heating. In the cool season, the operation of the heat pump is sufficient; the heater does not need to be used during this period.

Types of equipment with admixture

As you already understand, only duct equipment with air ducts and heating can fully cope with replacing air with fresh air. However, some other types of models can also ventilate, but within 10% of their capacity.

The share of fresh air is often called “admixture”; the bulk of the air masses is occupied by the “exhaust” processed in the indoor unit.

Traditional wall models

Models whose internal unit is mounted on a wall are the most popular for the improvement of residential premises.

There are models that provide a comfortable microclimate on an area of ​​10 m², but there is also more powerful equipment designed for rooms up to 100 m². Not long ago, inverter models equipped with a supply and exhaust fan appeared.

Regardless of whether the air conditioner is operating in heating or cooling mode, the supply and exhaust system can operate in parallel. An example of a wall-mounted device with the function of supplying air from the street is the Air Exchanger series of the famous HITACHI brand.

Before being supplied to the room, the air mixture is cleaned by a filter system from exhaust gases, carbon dioxide, formaldehyde, etc., and foreign odors are destroyed.

The wall-mounted evaporative unit can be installed anywhere in the room, but the area near the window is preferable. The shorter the line between the indoor and outdoor units, the higher the productivity of the equipment. Wall-mounted models are distinguished by a pleasant design and a large range of additional options.

Cassette air conditioning systems

Often in public buildings you can find air conditioners with cassette-type internal modules. Such systems are suitable for servicing large areas - from 40 m² to 150 m². They have high performance and are distinguished by minimal noise levels.

The working part of the models is located above the suspended ceiling structure; only a decorative grille of a standard size of 60x60 cm is visible. The moving parts of the grille are controlled from a remote control or from an adjustment panel mounted on the wall

The performance of cassette air conditioners is from 3 kW to 15 kW, the main functions are lowering the temperature in the room or operating in heat pump mode.

A common design is in which air is taken from the hall through a central hole, and supplied through four guides in different directions. If one cassette is used, then it is mounted in a suspended structure in the center of the room.

On the market you can find both traditional modifications and cassette systems with admixture. For example, Airwell CK air conditioners are designed for installation of multi-split systems and, thanks to the built-in heater and air ducts, provide a dosed supply of fresh air.

Advantages: beautiful design and high performance; disadvantage: installation only in a suspended structure.

Floor-ceiling devices

In some rooms there are no conditions for installing cassette models, and the performance of wall-mounted air conditioners is not enough. In this case, universal floor-ceiling devices are used, which have fastenings both for installation on the floor and for hanging from the ceiling.

The Japanese company Daikin specializes in the production of floor-ceiling devices with a mixture of 10% fresh air. New supply models save up to 30% of electricity and have a high cost - from 60 thousand rubles. and higher

Air conditioning is carried out thanks to a stream of purified air, which is directed along the ceiling or wall - depending on the installation location. The highest power of the devices is 15 kW, but for relatively small rooms (40 m²) equipment with parameters of 5-6 kW is sufficient.

Column models of split systems

As the name suggests, air conditioners are shaped like columns directed toward the ceiling. They surpass other types in power (on average 17 kW) and can serve rooms up to 180 m².

The operating principle of column-type models is the same as that of previous air conditioners, but they differ in the supply of purified air. The jet is directed not along the walls or to the center of the room, but towards the ceiling. There, the cooled air diverges in different directions and descends, displacing the already heated air.

An example of a column device with inflow mode is General Climate GC. The air exchange is more than 1900 m³/h, and the heating power is 22 kW. Cost – 109 thousand rubles.

Recirculation models with a partial mixture of clean air have high performance, but their noise level is higher than that of steel types - up to 50 dB.

Benefits of multi-zone air conditioning

Multi-zone maintenance of premises is a more advanced version of multi-split systems, which creates a certain microclimate over a large area. Fundamental difference from standard split systems – increased length of highways connecting modules located in different places.

Advantages of a multi-zone system:

• up to 20 internal units can be connected to 1 remote unit;
• the distance from the internal module to the external one is up to 150 m (in some cases more);
• height difference between modules is 50 m.

Thanks to the listed parameters, the remote outdoor module is installed in the most convenient remote locations - in the attic, roof, in the yard behind a fence, etc.

Scheme of possible installation of the outdoor unit. If for some reason installation on the roof cannot be carried out, the module is installed directly in the courtyard of the house, ensuring safety

The multi-zone system is more economical, since the control inverter climate control equipment allows you to change the power of the system depending on the number of functioning indoor units.

In this case, you can use modules that are completely different in type and performance. Adjustment and control over the operation of all equipment can be done in system mode, from one remote control.

You can compare conventional and inverted climate control systems and get an idea of ​​their pros and cons by reading our proposed article. Before making a decisive choice, it is worth familiarizing yourself with useful information.

Tips for choosing air conditioners

Before purchasing a split system for home use or office use, you must first decide whether ventilation is needed. Perhaps the room is equipped with an effective ventilation system and does not need additional devices of this type.

If air exchange is weak, pay attention to models of supply air conditioners.

For rooms with high ceilings, any built-in models are suitable - duct, cassette. But do not forget that to disguise the working elements you will have to erect a suspended structure

If the ceilings are low (for example, 2.5 m), the idea of ​​​​ceiling models will not suit you. Perhaps, based on the technical characteristics, you can select a device with a wall-mounted module, which simultaneously introduces air from the street.

For larger rooms, a more efficient model will be required, for example, with a floor-ceiling installation. Hotel lobbies, foyers and lobbies are characterized by large volumes. In addition to duct systems, column models are installed in them, characterized by productivity and high air exchange rates.

Regardless of the type of device, it is necessary to analyze its technical characteristics and performance characteristics: clarify what area the model is designed for, what its power is, whether it is possible to connect additional modules.

The latest programmable air conditioners with a large list of additional options are much more expensive, but some features are truly important.

He will introduce you to the guidelines for choosing a split system for arranging a country house and a city apartment. next article, containing information with answers to questions from potential buyers.

Conclusions and useful video on the topic

To better understand the design and principle of operation of air-conditioned split systems, we suggest watching overview videos.

Video #1. Review of Haier duct air conditioners:

Video #2. About the advantages of channel type models:

Video #3. More information about multizone systems:

To enrich the air in a room with oxygen, it is not necessary to keep a window open or install additional ventilation. Sometimes it is enough to wisely choose an air conditioner model that, if necessary, will not only cool/heat the room, but also carry out air exchange.

Please write comments in the block below. You may be aware of the nuances of choosing and installing air conditioners that provide fresh air that are not covered in the article. Ask questions, share useful information and your own opinion, publish thematic photos.