Understanding Fan Coil Units: Types, Functions & Benefits

Are you familiar with fan coil units and how they operate? A fan coil unit (FCU) is an essential component of modern HVAC systems, playing a pivotal role in maintaining indoor comfort. At its core, a fan coil unit is a simple device comprising a fan and a coil – either for heating or cooling. FCUs are versatile and can be used across various settings, from cozy homes to expansive commercial facilities.

The function of an FCU in a heating and cooling system is to regulate the temperature of a space by circulating air over coils filled with hot or cold water or refrigerant, depending on the system’s design. This process ensures that the desired climate control is achieved efficiently and effectively within a building’s different zones.

In this article, we will delve into three types of fan coil units:

  1. Chilled water fan coil units: These units are connected to a central chilling system and circulate cold water through the coils.
  2. Ducted concealed fan coil units: Typically hidden from view, these units distribute air through ductwork, offering an aesthetic solution without compromising performance.
  3. Non-ducted exposed fan coil units: These units are visible in the space they serve and directly circulate conditioned air without the need for ducting.

Each type has distinct features and uses that we will explore further, providing insights into how they fit into diverse HVAC requirements.

What Are Fan Coil Units

A fan coil unit, commonly known as FCU, is a device with key components including a fan and a coil. It is designed to control the temperature within individual spaces of a building. Here’s a closer look at its parts and how they work together:

Parts of an FCU

  • Fan: The fan circulates air from the room over the coil.
  • Coils: These are where the heat transfer happens. They can be connected to either a chilled water system or hot water systems.
  • Filter: Air is filtered before passing through the coils.
  • Casing: This houses all the components of the FCU.

How an FCU Works

When an FCU is activated, here’s what happens:

  1. The fan pulls room air through the filter.
  2. Either warm or cold water flows through the coils.
  3. Room air comes into contact with these coils, resulting in a thermal energy exchange.
  4. The fan then pushes the temperature-adjusted air back into the room.

This process allows fan coil units to maintain desired temperatures and improve indoor air quality through filtering mechanisms.

The Relationship Between FCUs and AHUs

Air handling units (AHUs) and fan coil units work together in larger HVAC systems. AHUs treat fresh air from outside before releasing it into a building’s circulation system. The conditioned air then passes through different zones with individual FCUs responsible for adjusting the temperature according to local needs.

Together, AHUs and FCUs ensure efficient heating and cooling across various areas of a building while optimizing indoor climate for comfort and health standards.

How Do Different Types of Fan Coil Units Differ?

Fan coil units (FCUs) are versatile components within HVAC systems, and they come in several configurations to suit various needs and preferences. The main types to consider include chilled water fan coils, ducted concealed fan coils, and non-ducted exposed fan coils. Each variant has unique characteristics that cater to specific applications.

Chilled Water Fan Coils

These FCUs use chilled water as the cooling medium, which is circulated through the unit’s coil.

Key Characteristics:

  • Temperature control is achieved by modulating the flow of chilled water.
  • Often connected to a central chiller system that serves multiple units.


  • Energy Efficiency: Utilizes chilled water from a central source, reducing energy consumption.
  • Quiet Operation: Typically quieter than direct expansion systems.


  • Infrastructure Dependency: Requires a complex system of chillers and pipework.
  • Initial Cost: Higher upfront investment in infrastructure.

Real-Life Example: In large office buildings, chilled water fan coils are commonly used for their efficiency and ability to be centrally controlled, making them ideal for maintaining consistent temperatures across expansive spaces.

Ducted Concealed Fan Coils

Ducted concealed FCUs are hidden within the ceiling or behind walls, connected to a network of ducts that distribute conditioned air.

Key Characteristics:

  • Air is delivered through ductwork, allowing for more uniform distribution.
  • Aesthetic integration into building design by being out of sight.


  • Aesthetics: Better visual appeal as the unit is not exposed.
  • Air Distribution: More consistent air distribution across larger areas.


  • Accessibility: Maintenance can be challenging due to concealed installation.
  • Space Requirement: Needs space for ductwork, which may not be available in all buildings.

Non-Ducted Exposed Fan Coils

These are standalone units where the FCU itself is visible within the space it serves.

Key Characteristics:

  • Does not require ductwork; each unit conditions air directly in its installed location.
  • Often feature individual controls for localized temperature management.


  • Flexibility: Easy to install and relocate if necessary.
  • Cost-effective: Lower installation costs without the need for ductwork.


  • Aesthetics: Less visually appealing due to being visible within the space.
  • Noise Levels: Can be noisier than concealed units due to direct exposure.

By comparing these types, one can discern that chilled water fan coils excel in efficiency but demand significant infrastructure. Ducted concealed fan coils offer an integrated look with effective air distribution yet require more space and can complicate maintenance. In contrast, non-ducted exposed fan coils provide flexibility and easy installation at the cost of aesthetics and potentially higher noise levels.

The Working Principle of Fan Coil Units in HVAC Systems

Fan coil units are an essential part of HVAC systems, playing a pivotal role in temperature regulation. Let’s delve into the workings of these units to understand their importance better.

Components and Operation

A fan coil unit comprises two primary components: a fan and a coil. The operation begins when the fan draws the room’s air into the unit. This air then passes over the coils, where heating or cooling occurs based on the temperature of the refrigerant or water flowing through these coils.

Heating Process

In heating mode, hot water from a boiler flows through the coils. As the room’s air passes over these heated coils, it absorbs heat and gets warmed up before being circulated back into the room. This process continues until the desired room temperature is achieved.

Cooling Process

When it comes to cooling, chilled water or refrigerant circulates through the coils. The warm room air passing over these cooled coils loses its heat, resulting in cooler air that is then distributed back into the room.

Benefits of Fan Coil Units

  • Provides individualized temperature control for separate spaces within a building
  • Standalone operation independent of a centralized system
  • Each unit is typically equipped with its own thermostat for precise control
  • Minimizes energy wastage by conditioning only occupied spaces

Understanding how a fan coil unit works helps appreciate their significant contribution to maintaining indoor comfort levels. As we delve deeper into this topic, we’ll explore other aspects such as benefits, applications, and cost considerations related to fan coil units.

Benefits, Applications, and Cost Considerations

Energy Efficiency

Fan coil units are lauded for their energy efficiency, which can translate into significant cost savings for property owners. By utilizing less energy to heat or cool spaces compared to some traditional HVAC systems, fan coil units can help reduce utility bills. The efficiency stems from the ability of FCUs to control the temperature of individual zones within a building, avoiding the unnecessary heating or cooling of unoccupied spaces.

Maintenance and Performance

To ensure fan coil units operate at peak performance, routine maintenance is key. Regular cleaning of filters, inspection of coils, and checks on electrical connections can prevent unexpected breakdowns and extend the lifespan of an FCU. Such preventive maintenance not only secures the unit’s efficiency but also sustains indoor air quality by eliminating potential contaminants that may circulate within the air stream.

Applications in Residential and Commercial Properties

Fan coil units have a broad range of applications spanning from single-room residential property installations to expansive commercial property systems.

Residential Applications

In residential settings, fan coil units are often implemented for their compact size and localized climate control capabilities. For example:

  • A high-rise condominium complex might utilize individual FCUs in each unit for personalized comfort and energy management.
  • Homeowners may opt for FCUs in specific rooms with unique temperature preferences, such as nurseries or home offices.

Commercial Applications

In commercial environments such as hotels or office buildings, FCUs provide flexible solutions for varied heating and cooling needs across different zones. A notable case study involves a large corporate office retrofitting its outdated HVAC system with fan coil units to achieve better temperature control and reduce operating costs.

Fan Coil Unit Cost Factors

When considering a fan coil unit’s cost, several factors come into play:

  • Unit Size and Capacity: Larger spaces require units with higher capacity, impacting the price.
  • Installation Complexity: The cost may vary depending on whether the FCU is a retrofit or part of new construction.
  • Features and Controls: Advanced features such as programmable thermostats or integration with building management systems can influence the total cost.
  • Quality and Brand: High-quality units from reputable manufacturers may carry a premium but often offer better longevity and warranty conditions.

By understanding these variables, individuals can make informed decisions that align with both their comfort requirements and financial considerations.

Troubleshooting Tips and Seasonal Maintenance Guide

When it comes to maintaining the efficiency of your fan coil units (FCUs), knowing some troubleshooting tips can be a game-changer. Just like any other HVAC component, FCUs can also run into issues. Here are some common problems that you might encounter:

Common Problems and Solutions

  • Noisy Operation: If your FCU is making unusual noises, it could be due to loose parts, an unbalanced fan, or motor bearings needing lubrication. Tighten any loose components, balance the fan, and lubricate the bearings to resolve this issue.
  • Inadequate Heating/Cooling: This could occur due to a dirty filter or coil, low refrigerant level, or a malfunctioning thermostat. Clean the filters and coils, refill the refrigerant (if applicable), and check the thermostat settings.
  • Unit Does Not Start: Check for tripped breakers or blown fuses in your electrical panel. If everything appears normal there, inspect the thermostat settings. If the unit still doesn’t start, consider consulting with a professional as the issue might lie within internal components.

Seasonal Maintenance Tasks

Keeping your fan coil units at their best performance also requires seasonal maintenance. These tasks are crucial for long-term operation of FCUs:

Spring/Summer Maintenance: Prior to peak cooling season,

  • Clean or replace air filters to ensure unrestricted airflow.
  • Inspect and clean the condensate drain line to prevent water damage from clogs. 

Fall/Winter Maintenance: Before heating season begins,

  • Again clean or replace air filters.
  • Inspect heating elements for wear or damage and schedule necessary replacements.

Remember that preventive maintenance is always more beneficial than reactive repairs. Regular checks will not only prolong the lifespan of your FCU but also enhance its performance significantly.

By understanding how to troubleshoot a fan coil unit and conduct seasonal maintenance for FCUs, you can ensure optimal efficiency and longevity of your HVAC system. Proper care and maintenance of these units, along with an understanding of how to troubleshoot common issues, can save you time, money, and discomfort in the long run.


When it comes to the definition of a fan coil unit, it’s clear that these components play a pivotal role in creating and sustaining a comfortable indoor climate. The synergy of heating and cooling coils with fans empowers these units to deliver precise temperature control, vital for both residential comfort and commercial efficiency.

Choosing the right fan coil unit involves considering various factors such as the type, size, and specific requirements of your space. Exploring the wide range of options is crucial – from the simplicity of non-ducted models to the sophisticated chilled water systems. Each variety offers unique benefits designed to cater to diverse HVAC needs.

Remember, an informed decision can lead to significant energy savings and contribute to a more sustainable environment. With this knowledge at hand, take the opportunity to assess your HVAC requirements and select a fan coil unit that aligns with your goals for efficiency, comfort, and cost-effectiveness.

Frequently Asked Questions

What is a fan coil unit and how does it work?

A fan coil unit is a type of air conditioning system that is commonly used in residential and commercial buildings. It consists of a coil, a fan, and a control system that work together to cool or heat a space. The fan coil unit is typically located in a room or space and is connected to a central heating and cooling system.

How does a fan coil unit cool a room?

A fan coil unit cools a room by drawing in warm air from the space and passing it over a chilled coil. The chilled coil removes heat from the air, lowering its temperature. The now-cooled air is then pushed back into the room by the fan, creating a cool and comfortable environment.

Can a fan coil unit also heat a room?

Yes, a fan coil unit can also heat a room. It works by drawing in cool air, passing it over a heated coil, and then pushing the now-warm air back into the space. This process is similar to how the unit cools a room, except the coil is heated instead of chilled.

How is the temperature controlled in a fan coil unit?

The temperature in a fan coil unit is controlled by a thermostat. The thermostat communicates with the control system of the unit, which then adjusts the speed of the fan and the temperature of the coil to maintain the desired temperature in the room.

Are there different types of fan coil units?

Yes, there are different types of fan coil units available, including horizontal, vertical, and ceiling-mounted units. These units may vary in size, shape, and location, but they all function in a similar manner to cool or heat a space.

What are the benefits of using a fan coil unit?

There are several benefits of using a fan coil unit, including energy efficiency, quiet operation, customizable temperature control, and lower installation costs compared to traditional central air conditioning systems. Additionally, fan coil units do not require ductwork, making them a versatile option for various building layouts.

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