What Is a Fan Coil and How Does It Work? A Complete Guide for Beginners

At Xiamen Beris Tech Co., Ltd., we're excited to launch a new blog series aimed at simplifying HVAC concepts for homeowners, installers, and facility managers. Whether you're upgrading your air conditioning system or exploring new HVAC technologies, it’s essential to understand how each component works.

In this first article, we’ll cover everything you need to know about fan coil units (FCUs) — from how they work, to where they’re used, and how they compare to other systems like split units.

      What Is a Fan Coil?

A fan coil (also known as FCU) is a compact and versatile device used to heat or cool indoor spaces. Unlike split-type air conditioners that rely on refrigerant, fan coils use water as their thermal medium. They’re typically made up of:

  ◆A coil (for heat exchange)

  ◆A fan (to blow air over the coil)

  ◆A filter, outer casing, and air grilles

Fan coils are commonly found in both residential buildings and commercial environments such as hotels, offices, hospitals, and shopping malls.

▶Related: Explore our range of fan coil-compatible thermostats

      How Does a Fan Coil Work?

Fan coil units receive hot or cold water from a central chiller or boiler. The water flows through copper tubes within the coil. When the fan runs, it pulls ambient air over the coil. As air passes over the cold or hot coil, its temperature changes due to thermal transfer.

Here’s the step-by-step process:

    ◆Hot or chilled water is supplied to the fan coil.

    ◆The fan draws air from the room through a return grille.

    ◆Air passes through a filter, then over the coil.

    ◆The treated air is blown back into the room via the supply grille.

This process allows for quiet, localized temperature control, making FCUs ideal for zoned comfort.

▶External Resource: ASHRAE: Understanding HVAC Systems

      Types of Fan Coil Units

Fan coils come in different configurations to suit various installation requirements and comfort levels. The two most common types are based on piping systems: two-pipe and four-pipe systems.

    1. Two-Pipe Fan Coil System

•   ◆One supply pipe and one return pipe
•   ◆Supplies either hot or cold water, but not both at the same time
•   ◆Simpler, more cost-effective
•   ◆Ideal for buildings with uniform seasonal needs

  2. Four-Pipe Fan Coil System

•   ◆Two supply and two return pipes
•   ◆Can heat and cool different areas simultaneously
•   ◆Provides better comfort and flexibility
•   ◆Commonly used in commercial buildings with high demands

Installation Types

Fan coils are also categorized based on installation:

•   ◆Wall-mounted
•   ◆Floor-mounted
•   ◆Ceiling concealed (ideal for hidden ducted installations)
•   ◆Exposed ceiling units

Some users confuse FCUs with direct expansion (DX) units like split ACs. Let’s explore the difference below.

 Fan Coil vs. Split AC Unit: What’s the Difference?

At a glance, a fan coil may look like a split unit, but the underlying technology is different:

 

Features	Fan Coil Unit	Split AC Unit
Heat transfer	Water-to-air	Air-to-air
Refrigerant	Uses water	Uses refrigerant gas
Energy source	Centralized chiller/boiler	Self-contained outdoor unit
Flexibility	More suited for zoned and centralized systems	Suited for individual room cooling

 

Fan coils are part of hydronic HVAC systems, while splits are part of DX (direct expansion) systems.

    Fan Coil Usage in Europe and Beyond

Although not the most common HVAC solution in Spain, fan coil systems are more widely adopted in other parts of Europe.

•   ◆France: Around 14% of HVAC units sold are fan coils.
•   ◆Italy: Fan coils account for nearly 30% of the market.
•   ◆Eastern Europe: High adoption due to energy efficiency and flexibility.

This growing popularity is due to increased demand for zoned control, quieter operation, and integration with renewable heating and cooling sources.

   Why Choose a Fan Coil System?

Fan coils are:

•   ◆Energy-efficient (especially with condensing boilers or chillers)
•   ◆Customizable for different rooms and building zones
•   ◆Quiet, especially in concealed or ducted designs
•   ◆Compatible with smart thermostats and BMS (Building Management Systems)

They are a great choice for commercial buildings and modern homes that prioritize comfort, energy savings, and long-term flexibility.

  Final Thoughts

Understanding how a fan coil unit works can help you make smarter decisions about your HVAC setup. Whether you're planning a new installation or upgrading an existing system, FCUs offer a reliable, flexible, and often more sustainable solution compared to traditional DX systems.

Ready to find the right thermostat or control solution for your fan coil system?
  ▶Browse Beris Tech’s fan coil compatible thermostats

Need expert help on selecting the right HVAC equipment?

Contact us at diane@beris-tech.com or visit www.beris-tech.com for personalized recommendations.