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

Alexey Dedyulin
Checked by a specialist: Alexey Dedyulin
Author: Tatyana Zakharova
Last update: April 2019

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

To solve the problem, forced ventilation is used. A modern air conditioner with an influx of fresh air is an example of an efficient and affordable HVAC 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 ventilation. In fact, in the regime of active air exchange with street air masses, only certain types of equipment can work. To make it clearer, to begin with, we will consider the device of a conventional split system.

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

The first module is an evaporative block, which is installed on the floor, suspended on a wall or partially masked with a ceiling lining. The second module is a remote condensing unit, usually mounted on the facade of a building.

Split system diagram with wall module
Schematic illustration of a device with an internal module mounted on a wall. Two modules are connected to each other by thin tubes of copper, along which freon moves. Tubes are hidden in strobes behind decorative trim or in plastic boxes (+)

The principle of operation of the air conditioner is simple. Through the intake grilles, room air enters the inside of the unit, where it is cooled, and then discharged through the air ducts.The change in air temperature is not based 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 liquid. To go into the gaseous phase, Freon takes part 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. Supply equipment is arranged differently. An example of a split system with the organization of fresh air flow is a channel type device.

Channel air conditioner design
The design scheme of the ducted air conditioner, which performs the functions of ventilation and temperature control indoors. A mandatory structural element is a heater integrated in the pipe (+)

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

What is the feature of multisplit systems?

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

They differ from ordinary ones in that they have only one remote unit, while there may be several internal ones. The minimum number is two modules, the maximum is limited to four. If you use a larger number of indoor units, the system will lose its performance and will not work at full capacity.

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

A multisplit system is not always used, but only in individual cases when the installation of a large number of outdoor units is not possible for a number of reasons:

  • the building is a historical or architectural monument;
  • there is a ban on the installation of remote units on the facade;
  • for the hitching of equipment, the architecture of the building provides for certain places limited in area.

Sometimes they refuse to mount a large number of remote modules for aesthetic reasons: the beautiful facade of the building, hung with dimensional buildings, looks unpresentable.

Facade outdoor units
The rules for the improvement of large cities are periodically amended to prohibit the placement of air conditioners on facades overlooking central streets. Exit - installation of the block on the courtyard wall of the building

The advantage of the multisystem is the installation of one remote module, the disadvantages are the complex work on the installation of pipelines, reduced productivity and reliability. In addition, all indoor modules must operate in identical modes: either for heating or for cooling.

Supply duct models

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

Well-designed and installed channel split-system copes with the tasks of ventilation, and with control over the indoor climate.

Distinctive features of the air conditioner with inflow

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

It looks like a simple recirculation model, not able to supply fresh air. In order for the system to perform the supply function, a built-in heater is required. This is regulated by the rules of SNiP, according to which the lower temperature threshold of the air masses coming from the street should be +14 ° С.

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

Channel model with a heater
The heating system is equipped with an automation unit, thanks to which the fresh air is regulated in various modes, depending on the season. The automatic unit is controlled using the remote control

Programmable supply systems are more expensive than conventional room modifications with a wall-mounted installation, but they are much more efficient and more functional thanks 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 working parts of the system are in an invisible zone, above the ceiling.

The principle of the supply system

To transport air from the street to the premises, air ducts are provided, which are not available in conventional split systems. First, the air from the street through the outdoor unit moves to the insulated channel, then to the mixing chamber. There, the incoming air is connected to the exhaust, refreshing it.

Then the air mixture passes through the filters and, according to the selected mode, is processed. Draining, heating or cooling of the air mass occurs. After that, purified, filtered, partially refreshed air of a given temperature enters the premises.

Air-conditioned room
Channel modifications with a mixture are used in large premises that are separated by non-capital partitions. These are apartments with ceilings from 3 m, clinics, catering establishments, sports and educational institutions, offices, etc.

As a rule, the maintained temperature is completely dependent on the season. In the summer, the supply air duct air conditioners work for cooling, in the winter for heating. In the cool season, the functioning of the heat pump is sufficient, the heater can not be used during this period.

Types of equipment with a mixture

As you already understood, only duct equipment with air ducts and heating can fully cope with the replacement of fresh air. However, some other types of models can also provide ventilation, but within 10% of their performance.

The fraction of fresh air is often referred to as a “mix”, the main part of the air mass is occupied by the “exhaust” processed in the indoor unit.

Traditional wall patterns

Models, the indoor unit of which is mounted on the 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 more powerful equipment designed for rooms up to 100 m². Not so long ago, inverter models appeared, equipped with a supply and exhaust fan.

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 outdoor air supply is the Air Exchanger range of the renowned HITACHI brand.

Air purification system
Before entering the room, the air mixture is cleaned by a filter system from exhaust gases, carbon dioxide, formaldehyde, etc., while odors are eliminated

A wall mounted evaporator unit is installed anywhere in the room, but the area near the window is preferred. 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 wide range of additional options.

Cassette air conditioning

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

Mounting the cassette unit
The working part of the models is placed above the suspended ceiling structure, only a decorative grill of a standard size of 60x60 cm is visible. The movable parts of the grill are controlled from the remote control or from the 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 working in the heat pump mode.

A design is widespread in which the air is taken from the hall through the central hole, and the air is fed in 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 mixed cassette systems. For example, Airwell CK air conditioners are designed for the installation of multi-split systems and, thanks to the built-in heater and air ducts, carry out a dosed supply of fresh air.

Advantages - beautiful design and high performance, disadvantage - installation only in a suspended structure.

Floor and ceiling devices

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

Floor and ceiling air conditioning Daikin
The Japanese company Daikin specializes in the production of floor-and-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 provided by 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 enough.

Columned models of split systems

As the name suggests, air conditioners in their shape resemble columns directed to the ceiling. They surpass other types in terms of power (17 kW on average) and can serve rooms of up to 180 m².

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

Columned General Climate GC conditioner
An example of a column device with an 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.

Partial recirculation models of pure air have high performance, but their noise level is higher than that of steel types - up to 50 dB.

The benefits of multi-zone air conditioning

Multi-zone room service is a more advanced version of multi-split systems that creates a certain microclimate over a large area. The fundamental difference from standard split systems - the increased length of the highways connecting the modules located in various places.

Advantages of the multizone system:

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

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

Outdoor unit mounting diagram
Scheme of possible installation of the outdoor unit. If for some reason it is impossible to mount on the roof, the module is installed directly in the courtyard of the house, ensuring safety

The multizone system is more economical because the control invert climate equipment allows you to change the power of the system depending on the number of functioning indoor units.

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

You can read the conventional and inverted climate control and get an idea of ​​their pros and cons by reading The article we proposed. Before making a decisive choice, you should familiarize yourself with useful information.

Tips for choosing air conditioners

Before purchasing a split system for home use or for office use, it is first necessary to 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 the supply air conditioner models.

Duct air conditioning in the interior
For rooms with high ceilings, any built-in models are suitable - channel, cassette. But do not forget that in order to mask the working elements you will have to erect a suspension structure

If the ceilings are low (for example, 2.5 m), the idea with ceiling models will not work. Perhaps, according to the technical characteristics, you can pick up a device with a wall module that simultaneously mixes air from the street.

For larger rooms, a more productive model, for example, with a floor-and-ceiling installation, will be required. The halls of the hotels, the lobby and the lobby are large. In addition to channel systems, column models are installed in them, characterized by productivity and high air exchange rate.

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

The latest programmable air conditioners with a large list of additional options are much more expensive, however, some functions are indeed important.

With guidelines for choosing a split system for arranging a country house and city apartment next articlecontaining information with answers to questions from potential buyers.

Conclusions and useful video on the topic

In order to better understand the device and the principle of functioning of supply split systems, we offer you to watch videos of an overview nature.

Video # 1. Overview of Haier duct air conditioners:

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

Video # 3. More about multizone systems:

To enrich the air in the room with oxygen, it is not necessary to keep the window open or install additional ventilation. Sometimes it’s enough to correctly select the model of the air conditioner, which, if necessary, will not only cool / warm the room, but also carry out air exchange.

Please write comments in the block below.Perhaps you are aware of the nuances not mentioned in the article of the choice and installation of air conditioners that provide fresh air. Ask questions, share useful information and your own opinion, publish thematic photos.

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Visitors Comments
  1. Basil

    There is some kind of trouble with split systems, the market is flooded with cheap Chinese counterfeit goods. Our masters did not have time to travel to different offices in the summer and accept requests for repairs. As soon as a little more than 25 degrees on the street - they immediately begin to break. And at the offices, they don’t understand split systems, they bought everything the cheapest on the market, and they want it to be cool and everything works, but it doesn’t happen, you have to pay for everything.

    • Expert
      Alexey Dedyulin

      The market, Vasily, is formed not by suppliers, but by buyers. In other words, what ordinary people buy, sellers buy. Russians do not have enough money for reliable split systems, and offices buy air conditioners through tenders. There is only one criterion - the supplier with the lowest cost wins.

  2. Just now, we are choosing an air conditioner for the home, as the bedroom windows are on the sunny side, in the summer it is simply impossible to be in the room, it is very hot. I had no idea that there are columned models of air conditioners! Its principle of operation and cooling of the room impresses me much more than that of the ceiling ones. Moreover, the ceilings in our house are low, so there are no options here - we will consider columned models.

  3. I do not trust these supply air conditioners. The inflow is carried out through a thin tube and gives out a maximum of 60 m3 / hour, and this is the norm for only one person. Despite the fact that the prices for these devices are high.

    • Expert
      Alexey Dedyulin

      You surprised me, Alex, with the realization of the phenomenon "flew into one ear, flew out of the other." After all, the whole section describes the operation of channel systems - there are no tiny tubes there. And some conventional split systems, the author constantly reminds, can provide no more than 10% of the fresh air flow - an honest warning that does not involve advertising.