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Difference between AHU and FCU Fan Coil Unit

Views: 35     Author: Site Editor     Publish Time: 2024-01-29      Origin: Site

When designing the HVAC (Heating, Ventilation, and Air Conditioning) system of a new space or retrofitting an existing one, certain factors must be considered. Among these factors is choosing between Air Handling Unit (AHU) and Fan Coil Unit (FCU) for the conditioning and distribution of air.


While they have many similarities, they also have some significant differences that are worth considering in order to select the perfect option for your space. Choosing an inefficient unit consumes excess energy and increases your building operational costs.

Therefore, in this post, we will discuss the differences between AHU and FCU, explaining what they mean, the types, structural design, working principle, pros, and cons.

What is an Air Handling Unit (AHU)?

An Air Handling Unit (AHU) is a small, centralized air conditioner or heater that’s installed in external spaces like rooftops. It can be installed alone or combined with other HVAC systems like humidifiers, dehumidifiers, or filtration equipment.

AHUs are commonly used in many types of heating systems for conditioning and circulation of air across many large buildings, like commercial and industrial facilities. They are made up of many components, such as fans, filters, dampers, and cooling & heating coils. Each of these parts are essential in ensuring the cleanliness of the air, controlling the indoor air, and regulating the airflow.

Air Handling Unit

The AHU is often supplied in parts, requiring a professional installer to bolt them together, thereby creating a larger single boxed unit. These parts are designed to handle larger volumes of air, making them suitable for a variety of high-demanding industries, such as food production, manufacturing, and healthcare.

Types of Air Handling Unit

AHU can typically be categorized into 2 parts. They are:

● Draw-through Air Handling Unit: This involves absorbing air through the fans, filters, heating or cooling coils, and air filters, then distributing them to the room through ductwork. The fan is installed after the coils, leading to negative pressure in the unit.

● Blow-through Air Handling Unit: This involves pushing out air through the fans, filters, heating and cooling coils, and air filters, then circulating them round the room via ductwork. The fan is installed before the coils, leading to positive pressure in the unit.


● Highly energy-efficient.

● Perfect for various HVAC systems and settings.

● Ideal for air distribution in larger spaces.

● The installation can be personalized specifically to your needs.

● Often equipped with advanced filtration systems for better indoor air quality.


● Requires larger installation space.

● Installation can be very complex; best done by an experienced professional.

● Maintenance routines on components like filters and coils can be challenging.

● High initial cost and installation cost.

What is a Fan Coil Unit (FCU)?

Now that you know what an AHU is, what is an FCU?

An FCU (Fan Coil Unit) is a powerful unit helpful in circulating cool or warm air across single spaces. It’s often installed within or near the space it serves. Unlike AHU, it has a simple design, with a singular system that can operate on its own to distribute air throughout a room. While it can be used in conjunction with an AHU, it can deliver large volumes of air with or without ductwork.

A major difference between AHU and FCU in HVAC is that while AHU can bring in outside air and cool it, FCU only works with the air inside the room. Because of this, FCUs are generally used to heat or cool small areas, like small-scale businesses or private gaming rooms in a casino.

Fan Coil Unit

They have various components, such as fans, coils, and filters that collaborate to regulate and distribute the air to every part of the room. Unlike AHUs, Fan Coil Units are supplied as a complete unit, allowing for portability during transport and easier installation.

Types of Fan Coil Unit

There are two primary types of FCUs. They are:

● Draw-through Fan Coil Unit: This involves drawing the air through the coil and filter before it’s distributed into the room by the fan. The fan is installed at the discharge side of the coil, making filter replacement and coil maintenance easier.

● Blow-through Fan Coil Unit: This involves pushing the air through the coil and filter by the fan before getting to the room. The fan is installed on the intake side of the coil, thereby limiting access for maintenance to the filter and coil.


● Has a compact design, making it suitable for smaller spaces and individual room.

● Allows for temperature control in individual rooms.

● Easier accessibility to components like filters and coils for maintenance.

● Doesn’t require ductwork for air distribution.

● Generally, less costly.


● Can’t handle larger spaces or buildings with extensive ductwork.

● Less energy-efficient compared to AHU.

● Produce more noise during operation.

● Can’t be customized to specific needs as much as AHU.

Difference between AHU and FCU

AHU and FCU differences can be better explained using their structural designs, working principles, and overall performance.

Structural Design

AHU FCU difference is largely noted from the structural design, as one has a more complex design, while the other is quite simple.

AHUs are integral components in the heat pump wholesale system. Their structural design is often characterized by size and complexity, as they feature many components, such as fans, filters, cooling & heating coils, and dampers in a single casing. These various components allow AHUs to manage the temperature, humidity, and air quality of large spaces efficiently. The modular nature of these units enables customization, making them suitable to diverse heating and cooling needs.

FCUs are often more compact and decentralized, with a simple structural design, consisting primarily of fans, coils, and filters. They are designed for localized air needs across different zones or rooms. While AHUs require ductwork for delivering air, FCUs can function without ductwork.

● Working Principle

Another notable difference between AHU and FCU can be seen in the working principle. Despite the fact that both HVAC systems are used to condition and regulate air, their working pattern differs.

AHU working principle revolves around centralized air processing for large spaces. The HVAC system absorbs ambient air from outside, then passes it through the various components embedded within the unit. After that, the conditioned air is distributed through an extensive number of ducts to the various parts of the building. This system is best suited for applications where uniform temperature is needed to be maintained throughout the whole building.

On the other hand, the FCU working principle is more decentralized. The HVAC system is designed to provide individual or zonal temperature control within a building. The FCU absorbs air from the indoor space through the fan, then sends it to the coil that heats or cools the air (depending on your requirement). After that, the conditioned air is released to the connected parts of the building.

● Overall Performance

This is a table highlighting AHU and FCU differences based on crucial factors and their overall performance.








Over 100KW

Average of 12KW




Ductwork Requirement

Solid ducting

Flexible ducting

Air Volume




Serves the whole building

Directly serving individual rooms





Can be complicated

Very easy

Installation Location

Plant room, rooftop, and other external spaces

Internal spaces

Installation Space

Requires more space

Requires lesser space

Design Structure

Manufactured in modules for easier shipping

Built as one complete unit


Usually from the side

Usually from underneath or the back

AHU vs FCU: Which One Should I Select for HVAC?

After examining the difference between AHU and FCU highlighted above, you must have seen that both HVAC systems have some uniqueness. One can’t replace the other, else your air conditioning and heating requirements won’t be fulfilled.

Hence, your selection should be primarily centered on your specific needs. For example, if you need an energy-efficient option that can deliver uniform temperature across various rooms in a building, AHU is the better choice. On the other hand, if you need an option that can deliver different temperatures to each room in the building, the FCU is the better choice.

Furthermore, if you want a less-expensive option with simple structural design, FCU is the better choice. But if you want an option with the capacity to handle larger volumes of air, the AHU is the better choice.

SPRSUN is one of the prominent air to water heat pump manufacturers in the world. We not only supply types of heat pumps but also fan coils, and water tanks for your heating and cooling system.  Do you need more professional insight on the best HVAC system for your needs, connect with us here.




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