What is fan coil unit: working principle and device

Published 30 Sep 2021
Updated 29 Nov 2023
11 мин чтения
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  1. What is a fan coil unit?
  2. Fan coil unit types
    1. Cassette fan coil units
    2. Ducted fan coil units
    3. Wall-mounted fan coil units
    4. Floor-mounted fan coil units
  3. How does a fan coil unit work?
  4. Advantages/disadvantages of fan coil units
  5. How to choose a fan coil unit?
  6. Chiller-fan coil system 
  7. Heat pump
  8. Which is better: chiller or heat pump?
  9. FAQ
    2. How does a chiller-fan coil system work?
    3. Which is better: cassette or ducted fan coil units?

If you need to purchase an efficient device for cooling and heating air, fan coil units are the best option. Today we will analyze what a fan coil is and how it works. 

This equipment allows you to create comfortable living conditions, despite the time of year and the area of ​​​​the room. Today, the market offers a wide range of fan coil units, which differ in types of placement, and have unique features. The fan coil unit is energy-efficient equipment, so the purchase costs will be compensated over time by its efficiency.

What is a fan coil unit?

Fan coil unit is an efficient equipment that is used to cool and heat a room to a predetermined temperature. The cold and heat generation for the fan coil unit is carried out using:

  • chiller;
  • heat pump.

The fan coil unit consists of:

  • a heat exchanger designed for air heating/cooling;
  • a thermostat that sets the temperature;
  • an engine;
  • containers for condensate collecting;
  • a regulator with which you can adjust the system for a comfortable stay;
  • a fan which is used to move air masses;
  • a filter that protects the mechanism from dust and various contaminants. Based on this, the fan coil unit maintains its technical characteristics and prevents the fungus from spreading into the room.

The movement in the fan coil unit is carried out with the help of a liquid, which is a heat carrier. It can be cold or hot depending on the purpose - cooling / heating.

We have already analyzed what a fan coil unit is and how it works. Let's move on to its types and systems with which it is used.

Fan coil unit types

First of all, the fan coil unit is a versatile device that has a unique design and is easy to use. Today, the market provides a wide selection of fan coil units, which differ in the placement of the fan coil unit in the room.

Considering various factors, such as location, installation or interior design features, the appropriate type of fan coil units is selected:

Fan coil unit types
  • cassette;
  • ducted;
  • wall-mounted;
  • floor-mounted.

Cassette fan coil units

A cassette fan coil is a device that is designed to cool / heat air. Thanks to the device, you can achieve a uniform temperature in rooms with a large area. The advantages are a low noise level and significant energy efficiency.

Generally, cassette fan coil units are suitable for industrial and administrative buildings. Installation of equipment does not harm the interior, as it is installed into the suspended ceilings. The advantage is that only the panel for air supply and exhaust will be visible on the ceiling.

Ducted fan coil units

The ducted fan coil unit is also in great demand, like the cassette fan coil unit. Generally, these units are used in residential buildings.

The advantages of ducted fan coil units are as follows:

  • installation of the system into suspended ceilings;
  • aesthetics;
  • smooth and uniform air distribution.

Wall-mounted fan coil units

Wall-mounted fan coil units are the most popular type of equipment. They have the following benefits:

  • affordable price;
  • a control panel to adjust temperature mode;
  • a wide choice of equipment design that suits any interior.

Floor-mounted fan coil units

Floor-mounted fan coil units are placed under the window to limit the flow of cold air in winter and heat in summer. The disadvantage of such fan coil units is the space occupied in the room. 

There are two types of fan coil unit connection:

  • Two-pipe fan coil units provide a system that has one heat exchanger. Thus, the equipment works for either cooling or heating of the premises.
  • Four-pipe fan coil units have two heat exchangers that are independent of each other. So, each performs its function. The first works for cooling, joining the pipeline with cold water. The second heat exchanger is used for heating the room during the cold period and is connected to the hot water pipeline.

How does a fan coil unit work?

The principle of operation of the fan coil unit is quite simple:

  1. Multiple or EC motor draws air and supplies it to the heat exchanger. *EC motor is a synchronous motor with smooth adaptation to the set temperature.
  2. Warm or cold liquid is supplied to the radiator. Based on this, the air is blown through the heat exchanger with warm/cold water.
  3. Warm or cool air, depending on the task, returns to the room.

Advantages/disadvantages of fan coil units

Fan coil units have the following advantages:

  • temperature control in the room, since the controller is provided in the design of the fan coil unit. It provides residents with the opportunity to adjust the optimal air temperature by zone for a comfortable stay;
  • energy efficiency;
  • possibility of installation into suspended ceilings;
  • simple temperature control system;
  • uniform air cooling in rooms;
  • environmental friendliness.

The disadvantage of the equipment is its noise characteristics. However, this problem is also solvable. By increasing the size of the fan coil unit, you can choose acceptable dB and achieve minimal noise level. 

How to choose a fan coil unit?

To choose the right fan coil unit, it is necessary to consider the amount of heat input in the house. In addition, to avoid high noise characteristics, it is necessary to pay attention to the standard size of the equipment: the higher it is, the quieter the fan coil will work.

For example: we will install a fan coil unit of the 3rd standard size in the room. To provide full cooling/heating, it must work at the 5th speed. In this case, the noise level will reach 65 dB. Of course, such high dB level is unacceptable.

fan coil unit

To solve this problem, it is necessary to increase the fan coil area by only 30%, and this will save users from discomfort. Therefore, choosing, for example, the 5th size, will enable the fan coil unit to operate at the 1st or 2nd speed at 25 dB.

As already mentioned, the fan coil unit only works together with a heat pump or chiller. Let's analyze these systems in more detail.

Chiller-fan coil system 

If you need to install a fan coil air conditioning system in industrial or administrative buildings, an excellent solution will be to purchase a chiller-fan coil system.

A chiller is a unit that contributes to the cooling / heating of a liquid, which is located on the roofs of buildings.

The principle of operation of such a system is as follows: after cooling / heating of the liquid in the chiller, it is supplied to the internal heat exchanger (fan coil unit). The system then supplies cold or warm air into the room, depending on the task.

Heat pump

A heat pump is an efficient and cost-effective device that is used for cooling and heating rooms.


  • cost-effective equipment. When absorbing 1 kW of energy, the heat pump can provide 3 kW of heat;
  • uses renewable energy;
  • works for cooling/heating of the room, and also heats water for hot water supply;
  • high power.

Types of heat pumps:

  • air-to-air – a budget and popular type of heat pump, which works both for cooling and heating. It is also a self-sufficient system.


  1. The system loses efficiency in severe frosts, so the best solution is to choose an air-to-water heat pump.
  2. Non-uniform air distribution.
  3. Cannot be used to heat water.
  • air-to-water – efficient equipment that works with the heating system. The disadvantage is the loss of efficiency if an outdoor temperature is -20 °C.

Which is better: chiller or heat pump?

Depending on the purpose of use, you can choose the optimal additional unit.

For industrial or administrative buildings, it is better to use a chiller-fan coil system, and for residential premises, a heat pump will be the right choice.

To sum it up: fan coil units are ideal equipment for maintaining the desired microclimate in both commercial and residential premises.



What a fan coil unit is and how it works can be found in more detail above.

The fan coil unit and the air conditioner have different heat carrier. Freon is used as a working fluid in an air conditioner, and water is used in a fan coil unit.

How does a chiller-fan coil system work?

Its principle of operation consists of several processes:

  1. Water (heat carrier) enters the chiller.
  2. The water is cooled or heated inside the chiller.
  3. Through pipelines, cooled or heated water passes into heat exchangers (fan coils).
  4. The air then contacts the heat exchanger and is cooled/heated.
  5. Then it is supplied to the room thanks to a fan.

Which is better: cassette or ducted fan coil units?

Depending on the type of building, the perfectly suitable type of fan coil units can be selected. If you need to install equipment in industrial or administrative buildings, the right solution will be to use a cassette type. If the room is intended for housing, ducted fan coil units will be the best option.

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  • 5 / 5

    Вадим Петрив

    Вы знаете, эта статья мне помогла понять, что такое фанкойлы и как они вообще работают. Это дало мне четкое представление о такой системе, не только, как отопления, но и охлаждения, к тому же она использует один блок для обеспечения комфорта в течение всего года. Фанкойлы более энергоэффективны и экологичны, чем другие аналогичные системы. Также представлена тут информация помогла мне понять, как правильно выбрать фанкойл для большой площади, учитывая такие факторы, как размер и мощность. Полезная статья для тех, кто рассматривает возможность установки фанкойлов для дома или бизнеса.

  • Команда Alter Air

    Дуже дякуємо, що виділили час для розгорнутого відгуку. Ваші слова - наше натхнення! Звертайтесь до Альтер Ейр, якщо буде потрібна консультація!

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