Difference between Fan Coil Unit and Air Handling Unit (AHU)

A Fan Coil Unit is part of a heating or cooling system that, by passing air over a coil containing hot water (in winter) and a coil containing cold water (in summer), is responsible for providing heating and cooling in the environment and warm or cool air inside the spaces. The building circulates.
Fan Coil Units include components such as a coil and an air blower, and based on their appearance, installation location, and intended use, they have various types of ground, wall, ceiling, channel, and ceiling fans. In terms of the number of coils in the Fan Coil Unit, Fan Coil Units are divided into two types, two-pipe, and four-pipe. Two-pipe Fan Coil Units in the spring and autumn seasons when temperature fluctuations occur, due to having only one coil and two inlet and return pipes in their water distribution system, unlike four-pipe Fan Coil Units that have a heating coil and A cooling coil and two hot water inlet and return pipes and two cold water inlet and return pipes do not provide the possibility of simultaneous heating and cooling in different spaces of the building.
In general, Fan Coil Units are used in all seasons of the year to provide the heating and cooling required for spaces that require separate temperature regulation and it is necessary to prevent the transfer and movement of air and pollution between different spaces, such as residential buildings. , offices, medical centers, hotels, etc. are used.
The low cost and structural diversity of Fan Coil Units have made them an attractive and significant option for houses and apartments. However, Fan Coil Units may be part of an air conditioning system or used to support air handling systems to cover areas not connected to air conditioning ductwork.

Click to view brands, models, and different types, find out the price, and buy AIR HANDLING units (AHU).

The task of the air conditioner is to ventilate and distribute air inside a building to achieve the internal comfort conditions of the residents in terms of temperature, humidity, and air filtration. In simple terms, an air conditioner is part of an air conditioning system that brings in fresh air from the outside, cleans it, and heats or cools it by passing the air through filters and coils, and finally through the ventilation channels of the ventilation air. and circulates hot or cold inside the building.
The air conditioner consists of several components such as a motor, air blower, heating and cooling coils, air filters, dampers, etc., and it is produced in vertical or horizontal, face-to-face or overhead, single-zone or multi-zone types.
The air conditioner must be calculated and designed accurately and according to the needs of the building to ensure that the air conditioning system works effectively. Because an inefficient air conditioning system consumes extra energy and increases building operating costs. In addition, an inefficient air conditioning system may break down, leading to maintenance problems and increased associated costs.
There are several options for the design and applicable structures in the air conditioner, which makes it possible to build an air conditioner based on the specific needs of the building.
Air conditioners usually have different control systems for different parts of their structure, for example, they may have several temperature sensors, actuators, and humidity sensors.

Comparison of Fan Coil Unit and air conditioner performance

Fan Coil Units are generally used to control the temperature of the space in which they are installed, while air conditioners are part of a larger system and in addition to temperature, they also control humidity, cleanliness, and air movement.
Air conditioners are more complex than Fan Coil Units and can have parts for humidification and reheating. Air handlers are also often equipped with vibration dampeners, mixing chambers, and other equipment, and since they bring air into the building from outside, they have filters in their primary section that remove contaminants and particles from the air. Do not contaminate other parts. While the fan coil is not as complex and expansive as the air conditioner and can circulate air in an environment without using ductwork.
On the other hand, due to the dimensions of the aerator and the extent of the network of aeration channels, the initial installation process of the aerator system is extensive and expensive. On the other hand, Fan Coil Units are much cheaper than air conditioners. You can also buy Fan Coil Units in various structures and suitable for the intended use and location.
Fan Coil Units have only one fan, while air conditioners sometimes use multiple fans. Ventilation fans in air conditioners are usually located at the end of the air conditioner or where the ducts begin so that other moving components that are part of the system can be accommodated inside the air conditioner.
Air conditioners can usually be installed in the basement, on the roof, or inside the floors of a building with the possibility of supplying fresh air from the environment, while Fan Coil Units are placed inside the building's interior spaces. For this reason, air conditioning systems equipped with air generators are quieter than Fan Coil Units.
In the following, the advantages and disadvantages of Fan Coil Units and air conditioners are discussed separately.

Advantages of Fan Coil Units

• It has suitable cooling and heating functions and the ability to separately control the temperature of different spaces in a building
• Compared to ducted systems such as air conditioners, it requires less space.
• Due to the wide range of different types of Fan Coil Units in terms of appearance and installation location (ceiling, ground, wall, channel, and ceiling), they have high flexibility to determine the installation position.
• It has the advantages of a central heating and cooling system, in addition to the possibility of independent separation of parts, and it is possible to turn off the unused Fan Coil Units in the uninhabited spaces of the building to reduce energy consumption.
• Installation of Fan Coil Units is cheaper compared to air conditioning systems equipped with air conditioners.
• Minimal transfer of air and pollution from one space to another space
• To change the existing heating and cooling system in a building, it is often easier to install the piping and wiring related to replacing a Fan Coil Unit system than to install the large ducts required to replace all-air systems such as air conditioners.
• Ability to heat or cool small spaces
• Suitable for connecting to solar refrigeration equipment or heat recovery

Disadvantages of Fan Coil Unit

• The distillation process occurs in summer and when cold water passes through the cooling coil
• Fan Coil Units must be equipped with distillation trays and a drainage system that must be cleaned regularly and unclogged.
• Disposing of distilled liquids can be difficult and costly.
• The Fan Coil Unit usually does not have the possibility of providing fresh air (except for the Fan Coil Units that are installed near the external walls).
• It is difficult to clean the coils in the Fan Coil Unit
• The filters used in the Fan Coil Unit are small and low-efficiency, and they need to be washed or replaced frequently to prevent the reduction of the output air volume and efficiency loss.

Advantages of the air conditioner

• It provides the possibility of air purification and regulation of temperature and humidity.
• External pollution does not enter the internal environment due to the installation of nets and filters and the applied pressure difference.
• Improving the quality of the outgoing air compared to the Fan Coil Unit that does not ventilate the air and only circulates the ambient air.
• The higher lifespan of ventilation ducts (they are usually installed above the false ceiling) compared to the Fan Coil Unit pipes (they run on the floor and the moisture in the environment and the ground causes them to rot)
• They perform better in humid areas compared to Fan Coil Units.
• The possibility of adjusting the temperature and humidity at different times of the day and night for the user
• Easy to change from cooling to heating mode due to automatic control systems
• The possibility of installing additional filters (paper filter, felt filter, bag filter, etc.) to improve the quality and cleanliness of the air coming out of the air conditioner.
• They have no limitations in terms of size and capacity and can be used in large spaces such as public buildings, hospitals, commercial and office buildings, large industrial sheds, halls and restaurants, department stores, mosques, etc.

Air conditioner disadvantages

• The implementation of ventilation channels requires a lot of space and reduces the useful space inside the building.
• Because it works for air conditioning when there is no need for heating or cooling, it increases electricity consumption.
• It is difficult to accurately adjust the amount of airflow and adjust the temperature of each space

In the end, the differences between Fan Coil Unit and air conditioner are briefly stated in the table below.

You can also read the article COMPARISON OF TYPES OF AIR HANDLING Units (AHU) for more information.

Determination of Fan Coil Units Capacity

The estimation of the required Fan Coil Unit capacity for each of the sizes presented in the table below is approximate based on the temperature conditions of the design inside and at the maximum speed of the fan, and in the medium speed, the correction coefficient of the ventilation volume of the Fan Coil Units is compared to the high speed. It is about 0.8 and the cooling and heating power is about 0.85. If you wish, you can also contact the experts of DamaTajhiz company.
In the table below, the approximate estimate of the Fan Coil Unit capacity required for such as Tehran, Mashhad, Karaj, Isfahan, Erbil, Kabul, Sulaymaniyah, Halba, and other cities with similar weather conditions is presented.

Approximate calculation of Fan Coil Unit capacity

The estimation of the required Fan Coil Unit capacity for each of the sizes presented in the table below is approximate based on the temperature conditions of the design inside and at the maximum speed of the fan, and in the medium speed, the correction coefficient of the ventilation volume of the Fan Coil Units is compared to the high speed. It is about 0.8 and the cooling and heating power is about 0.85. If you wish, you can also contact the experts of Damatajhiz company.
In the table below, the approximate estimate of Fan Coil Unit capacity required for cities weather conditions such as Mashhad, Karaj, Isfahan, Erbil, Kabul, Sulaymaniyah, Halba, and Beirut is presented.

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Final speech

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