Understanding Fan Coil Units

Colby Maun • August 3, 2026

For buildings that require targeted zoning, such as hotels, offices, apartments, hospitals, retail spaces, and more, fan coils can assist in maintaining a comfortable indoor temperature. Each fan coil unit serves a particular space, which allows individual occupants to control their area of a building without affecting the rest of it. Understanding fan coils and how they work can help facility managers of these styles of buildings more properly maintain and replace units to prevent downtime in their systems. Here is a breakdown of how they work, the different types, and the common problems that they run into in their life cycle.

How a fan coil unit works is not complicated to understand. Initially, room air is taken into the unit and passes through a filter that removes dust or debris. This clean air is then blown across a hot or cold-water coil depending on whether the room needs to be cooled or heated. A thermostat in each individual space is used to decide this and monitors the temperature in the air. After the air passes through the coil, more fans distribute the air back into space. This process then repeats as many times as needed to maintain a comfortable temperature. For commercial buildings, a central plant in the building serves many individual spaces, with each space having its own fan coil unit. This eliminates ductwork.


There are 2 broad types of fan coils, vertical and horizontal. Vertical fan coils are typically used for smaller spaces, as they are mounted vertically on walls or ceilings, and take up less space when every inch matters. Horizontal fan coils are the opposite and commonly used in larger areas since they are installed horizontally. Within horizontal fan coils, there are an additional 3 categories: concealed ceiling, exposed ceiling, and under-floor. The concealed ceiling unit is mounted above the ceiling and ducted to the space via grilles, which hide the unit for aesthetics. The exposed ceiling unit is mounted the same way as the concealed unit; however, the unit will be exposed. The under-floor is mounted under the floor and is the rarest of the 3 horizontal types. Making sure that you select the type of fan coil that is best for your application will maximize efficiency in your building and provide easier maintenance moving forward. 

Fan coil units experience similar failures to most other coils. Corrosion, leaks, dirty coils, and airflow restrictions are some of the most common failures that they can experience. While proper maintenance is the best way to prevent these issues, fan coils do not last forever. When your coil experiences frequent breakdowns due to one of these issues, or begins to decline in efficiency and performance, it may be time to replace it.


At HeatEX Technologies, we carry Multiaqua fan coils renowned for their silent operation, ductwork elimination, and zoning flexibility. These fan coil units are dependable and effective across several different kinds of applications. If your fan coil has recently failed and needs replacement, give HeatEX Technologies a call, and we can assist you with your replacement job. Additionally, check out our Multiaqua Fan Coils page under the Our Products dropdown on our website to learn more. 

Works Cited



Construct & Commission. “What Is a Fan Coil Unit?” Construct & Commission, https://constructandcommission.com/what-is-a-fan-coil-unit/. Accessed 3 Aug. 2026.


Trane. “What Is a Fan Coil Unit?” Trane Residential, https://www.trane.com/residential/en/resources/glossary/what-is-a-fan-coil-unit/. Accessed 3 Aug. 2026.


Zero HVACR. “Fan Coil Units Explained: A Practical Guide to Types, Applications, and Selection.” Zero HVACR, https://zerohvacr.com/blogs/fan-coil-units-explained-a-practical-guide-to-types-applications-and-selection. Accessed 3 Aug. 2026.

Which Material is Best for your Coil?

By Colby Maun • July 27, 2026
In commercial HVAC, one of the largest yet overlooked aspects of a custom coil replacement job is the materials that the coil is made of. Different materials thrive better in different systems and environments, which affects the lifespan and efficiency of the coil. Making sure that your replacement coil is best suited for your unique system and location is integral to any facility, and failure to do so can increase costs and decrease reliability. Here is a breakdown of each material in your coil and what scenarios to select each in.

What Actually Goes into Measuring a Coil

By Colby Maun • July 20, 2026
For any coil or heat exchanger replacement job, one of the first steps in the process is for HeatEX Technologies to measure the existing coil/heat exchanger to ensure a perfect fit in the unit. Recently, I had the privilege of going out to my second job site to take measurements with HeatEX Technologies. Here is my account of what actually goes into measuring a coil, and my experience from start to finish.

Trane CGAM070 Microchannel Conversion Case Study

July 13, 2026
After multiple refrigerant leaks sprang from a Trane CGAM070 air-cooled chiller in West Palm Beach, FL, our customer faced a difficult challenge. They had to decide whether to replace the failed microchannel condenser coils with new OEM microchannel coils or pivot and invest in a different, longer-term solution. After much evaluation, our customer decided to convert the chiller from aluminum microchannel coils to copper tube aluminum fin condenser coils.

The Biggest Takeaways from the 2026 ASHRAE Annual Conference for Commercial HVAC

By Colby Maun • July 6, 2026
Last week, from June 27 th to July 1 st , ASHRAE held its 2026 Annual Conference in Austin, TX, and brought together more than 2,233 HVAC professionals from all over the world. The conference covered a broad range of many topics prevalent in the industry today, from fundamentals and applications to AI in building design and construction. Here are some of the biggest takeaways from the 2026 ASHRAE Annual Conference for commercial HVAC.

5 Warning Signs Your Coil Needs Replacement

By Colby Maun • June 29, 2026
In a commercial HVAC unit, coil failure is one of the most frequent and costly problems a system can have. Coil failure in a commercial HVAC unit leads to performance, efficiency, and reliability issues, making it one of the most important aspects in the system. Coils can fail for many different reasons, and understanding when a coil is starting to need replacement can save facility managers tons of extra downtime and stress. Here are 5 warning signs that your commercial HVAC coil needs replacement, so that the next time your coil fails, you can be on top of the problem.

What Makes a Coil Custom?

By Colby Maun • June 22, 2026
What exactly makes a custom coil custom? Most facility managers assume that a custom coil only differs from OEM in sizing. The reality is that dimensions are only a fraction of what makes a custom coil custom. Each job is different, with many different factors going into a custom coil, such as dimensions, tube configuration, fin design, materials, and performance requirements. The most commonly thought of aspect when it comes to custom coils is the dimensions. This includes height, width, and depth of the coil, which allows for custom replacement coils to fit perfectly into the system they are designed for. Doing this without major modifications is crucial when manufacturing a custom replacement coil. The tube configuration of the coil also plays a very important role in customization. The circuitry, number of rows, and tube diameter all impact this aspect and contribute to the efficiency and heat transfer of a custom coil.

How Aging Infrastructure is Challenging Commercial Buildings

By Colby Maun • June 18, 2026
As a building gets older, it becomes much more likely to experience several different types of HVAC failure, which results in decreased efficiency and reliability in the system. Considering the fact that most commercial buildings in the US were built between 1970 and 2000, this aging infrastructure is becoming increasingly problematic in the world of HVAC. To increase difficulty, many organizations postponed renovation and retrofit projects during COVID and during times of economic uncertainty and inflation. Those decisions extended HVAC equipment beyond its initial design life in many cases, and now that it is finally time to renovate, there are significant challenges to doing so in those buildings. With today’s rising equipment costs, aging building stock, high energy costs, sustainability pressures, and limited budgets, many facility managers are burdened with attempting to keep their equipment running smoothly. As HVAC systems age, they experience coil degradation, efficiency losses, corrosion, and increased failures and downtime in general. Coils are usually one of the first parts to deteriorate, as they are exposed to plenty of different weathering aspects in the air, such as salt, moisture, and pollutants, to name a few. When a coil deteriorates, it reduces system capacity as a whole. Efficiency losses in older units are common as well, since with time, the unit has to work harder and harder to remain operating at the same capacity as it was when it was new. Reliability decreases for units due to increased unexpected failures and downtime, along with it becoming harder to source parts for repairs as technology advances and changes.

YCAV Air-Cooled Chiller Conversion Case Study

June 11, 2026
Location: Hotel – Fort Lauderdale, Florida  Overview: A 6-year-old York YCAV air-cooled chiller serving a hotel experienced premature condenser coil failure. Out of 10 total coils, 4 had already failed (40%), with the remaining coils showing active corrosion. The unit operates continuously, making reliability critical for guest comfort

HVAC's newest Refrigerants

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How AI is Reshaping the Future of HVAC

June 5, 2026
Increasing demand for AI, high performance computing, along with hyperscale data center expansion are creating a massive new market for HVAC. The shift is in cooling, as data center cooling is moving beyond incremental airflow optimization, and towards liquid cooling in order to support AI and its specific cooling needs. Because of this, the data center liquid cooling market is projected to expand from 6.6 billion dollars to 38.4 billion dollars by 2033. North America is the current hotspot for this investment as it hosts the largest concentration of AI training clusters globally. Historically, data centers have relied on air-based systems for their cooling, which includes CRAHs, chilled water systems, and precision cooling equipment. Because AI servers are now generating higher heat loads than previously (Modern AI racks can exceed 100 kW per rack compared to the traditional 5-15 kW loads of the past), facilities need heavier duty cooling, sparking the transition to liquid cooling solutions. This transition to liquid cooling is not removing HVAC systems and instead restructures their role within AI facilities. Removing building heat, maintaining environmental conditions, and supporting chilled water distribution systems are all issues that HVAC remains a critical solution to. As a result of this, specialized coils, such as the ones HeatEX produces are growing in demand along with cooling towers, heat exchangers, and other thermal regulation components necessary for dealing with high heat rejection requirements. This trend to support AI with Liquid cooling brings new challenges with infrastructure and compatibility for projects, as operators prioritize power usage effectiveness reduction and carbon footprint optimization. Ensuring coolant compatibility with diverse server architectures, leak prevention, and aligning cooling with rapidly advancing cycles are a few of these challenges. Operators are looking for companies that can specialize towards their plants and customize them to their need.