A fan coil unit (FCU) heats and cools by passing hot or chilled water from a central system through a coil, while a fan draws room air across that coil. The working principle is the same in every fan coil; the differences come from the casing type and mounting position and from the system features (number of pipes, motor, additional heater). These differences directly determine installation, air distribution, noise and, above all, access for maintenance and service.
Below we describe the common fan coil types, where they are used, their advantages, what to watch out for and what to expect on the service side, based on our field experience.
Cassette fan coils
A cassette fan coil is recessed into the suspended ceiling; only the panel carrying the supply and return grilles is visible. Air is drawn in through the centre of the panel and delivered into the room through the louvres at the edges. It is the most common fan coil type for large spaces with suspended ceilings, such as offices, shops, meeting rooms, restaurants and cafés.
Sub-types: 4-way, 1–2-way and 360° round-flow
4-way cassette: distributes air in four directions; placed in the centre of the room it gives the most even distribution. 1–2-way cassette: used where air needs to go in one or two directions, such as corridors, narrow rooms or along a wall. 360° round-flow cassette: delivers air all around; preferred in high-ceilinged and open-plan offices to reduce draughts.
Advantage: takes up little ceiling space, needs no ductwork, and installation and commissioning are relatively quick. Watch out: it must suit the ceiling grid module and the void height; the position should be chosen so that the louvres do not blow directly onto desks or beds.
Related (in Turkish): Concealed ceiling or cassette? · Cassette panel and grille · Condensate pump · Swing louvre fault
Concealed ceiling (ducted) fan coils
A concealed ceiling fan coil is completely hidden in the suspended ceiling; air is distributed into the room through a short duct and linear or square diffusers in the ceiling, and return air is taken through a separate grille. Because the unit is not visible, it is the most popular type in hotel rooms, residences, homes and prestige offices.
Sub-types: low, medium and high external static pressure
Low pressure: for applications with a short duct or none, with the diffuser close to the unit. Medium pressure: used with medium-length ducts serving several diffusers. High external static pressure (high-pressure ducted): chosen when there is a long duct, many diffusers or additional resistances such as filters or silencers; common in large halls and in units serving more than one zone.
Advantage: aesthetics; air distribution can be designed for the space and unit noise can be kept away from the room. Watch out: if the duct and diffuser selection does not match the unit's pressure, airflow will be weak or noisy. An adequately sized access panel must always be left in the suspended ceiling.
Related (in Turkish): Concealed ceiling plenum cleaning · High-pressure ceiling fan coils · Fan coil blowing weakly
Exposed (cabinet) ceiling fan coils
An exposed ceiling fan coil is a unit with a painted outer cabinet, hung openly from the ceiling. It is used in spaces without a suspended ceiling, or where the ceiling void is not deep enough, and usually blows air forward along the ceiling.
Where is it used?
Offices and shops without suspended ceilings, office sections inside warehouses, workshops, and areas in existing buildings that later need air conditioning.
Advantage: no suspended ceiling needed; installation and maintenance access are easy. Watch out: as the unit is visible, aesthetic expectations should be considered; the visible parts of the drain line and pipework must be run neatly and insulated.
Related: Fan coil installation · Fan coil leaking water
Floor-standing fan coils (cabinet and concealed)
A floor-standing fan coil is usually placed under a window, close to the floor, and blows air upwards towards the glass. This counters the cold-wall effect of the glazing in winter and the solar load along the façade in summer. It is very common in hospital rooms, school classrooms, office façades and older buildings.
Sub-types: cabinet (cased) and concealed (uncased)
Cabinet (cased, exposed) floor-standing: installed visibly in its own decorative cabinet, with a supply grille on the top or front. Concealed (uncased) floor-standing: a unit without a cabinet, hidden inside furniture, under a window sill or in a plasterboard box; air is delivered through grilles.
Advantage: no suspended ceiling needed; comfortable in heating mode because warm air is delivered from low down. Drainage can usually be by natural fall. Watch out: the front must not be blocked by furniture or curtains; with concealed types, the box must have sufficient intake and outlet openings.
Related: Floor-standing vs wall-mounted fan coils (in Turkish) · Cleaning and filter replacement
Wall-mounted fan coils
A wall-mounted fan coil looks similar to the indoor unit of a split air conditioner; it is hung on the upper part of the wall and blows air down into the room. The difference is that water from the central system circulates inside it, not refrigerant.
Where is it used?
Rooms and offices without suspended ceilings, areas that need a quick solution during renovation, and small rooms in hotels and homes.
Advantage: simple to install, space-saving, usually operated by remote control. Watch out: the drain line must run down inside the wall with sufficient fall, and the valve set must fit inside the casing; as space is limited, valve and connection details are important.
Related (in Turkish): Remote control not responding · Fan coil or split air conditioner?
Floor–ceiling (console) fan coils
A floor–ceiling fan coil is a console type that can be installed either vertically on the floor or horizontally on the ceiling. It offers flexibility when the layout is not yet final at the design stage, or when one unit type is wanted for different positions in a building.
Where is it used?
Offices, shops, classrooms, apartments and villas; mounted on the ceiling in rooms where the façade is unsuitable, and on the floor under windows.
Advantage: one model, two mounting options; spare parts and stock management become simpler. Watch out: check that the drain pan and drain outlet are positioned correctly for the mounting option; drain fall matters for ceiling mounting, and keeping the front clear matters for floor mounting.
Related: Fan coil maintenance
Vertical and horizontal mounting
Most uncased (concealed) fan coil chassis can be installed vertically (on the floor, in front of a wall) or horizontally (on the ceiling, inside the suspended ceiling). Catalogues often offer the same series in "vertical" and "horizontal" versions.
What does the mounting orientation change?
The orientation determines the position of the drain pan, the direction in which the filter is removed, the side for the water connections and the air inlet and outlet openings. That is why the orientation and connection side (right/left) must be specified correctly when ordering a unit.
Watch out: hanging a unit built for vertical mounting horizontally (or vice versa) can leave the drain pan unable to handle the condensate and cause water to overflow.
Related (in Turkish): How is fan coil pipework installed?
Slim and decorative types
Slim fan coils have less depth than standard floor-standing types and protrude less from the wall. In decorative types the front panel, colour and material are designed to suit the interior; some models look like radiators.
Where is it used?
Homes, hotel rooms, boutique offices and areas where appearance matters; renovation projects in which fan coils replace radiators.
Advantage: aesthetics and space saving; most models are designed with quiet operation in mind. Watch out: as the casing gets smaller, the internal volume, coil and fan size are limited; capacity must be selected carefully for the space. Check whether the valve set fits inside the casing.
Related: Fan coil spare parts · Fan coils in villas and detached houses (in Turkish)
Types used in primary (fresh) air and air–water systems
On its own, a fan coil recirculates room air; it does not supply fresh air. In air–water systems, fresh air is conditioned in a central air handling unit and supplied to the rooms separately, while the fan coil covers the room load. This "primary air" arrangement is common in hotels, hospitals and offices.
How is it applied?
Fresh air is either supplied to the room through a separate diffuser or connected to the intake side (plenum) of a concealed ceiling fan coil. In the second case the fan coil must have a casing suitable for a fresh air duct connection; ducted/concealed ceiling types are mostly used for this.
Watch out: when fresh air is fed into the unit's intake, the filter gets dirty faster; in winter, unconditioned air can create a risk of coil freezing. The fresh air damper and air handling unit settings should be considered together with the fan coils.
Related (in Turkish): Primary air fan coils and fresh air · Coil freezing in winter
Hygienic application types
For hygiene-sensitive areas such as hospitals, laboratories and food facilities, some manufacturers offer "hygienic" series with features such as easy-to-clean surfaces, removable drain pans, better filtration options and an interior that is easy to disinfect.
What to look for in general
An easily removable and washable drain pan, interior surfaces with few corners, a suitable filter class option and easy access to the filter. Which features are available varies by brand and series; the unit's catalogue information should be the reference.
Watch out: even a hygienic unit gets dirty in the drain pan and coil if it is not maintained regularly. The maintenance interval is as decisive as the unit type.
Related (in Turkish): Fan coil disinfection · Washable antibacterial filter · Bulk maintenance in hotels and hospitals
Fan coil types by system
Regardless of the casing type, every fan coil is also classified by the number of pipes, the motor type and whether it has an additional heater. From a service and spare parts perspective, this distinction is at least as important as the casing type.
2-pipe and 4-pipe fan coils
In a 2-pipe system the unit has a single flow and a single return line; chilled water in summer and hot water in winter pass through the same line, and the building is in either heating or cooling mode depending on the season. A 4-pipe system has separate hot and chilled water lines, usually with two separate coils or a two-circuit coil; each room can heat or cool according to its own needs at the same time.
The difference from a service perspective
On 4-pipe units the number of valves, actuators and connections doubles, and the thermostat must also be suitable for 4-pipe control. On 2-pipe systems the changeover setting must be made correctly at the change of season.
Related (in Turkish): 2-way and 3-way valves · Changeover setting · Motorized valve failure
AC (3-speed) and EC motor fan coils
Conventional fan coils use AC motors with three (sometimes more) speeds; the speed is selected via the tap connections on the motor winding. In units with EC motors, an electronically controlled motor adjusts the speed steplessly according to the signal from the thermostat.
Which is preferred and why?
AC motor: simple design, widely available parts, easy repair. EC motor: lower electricity consumption, quieter and more precise speed control; on the other hand, it requires a compatible thermostat or control signal.
Related: Fan coil motor · EC motor conversion (in Turkish) · Fan speeds not working (in Turkish)
Fan coils with electric heaters
Some fan coils have an electric heater (heating element) in addition to the water coil. It is used especially in 2-pipe systems to provide additional heating in the transitional seasons or when the central heating is not running.
Points to watch
An electric heater directly affects the unit's power supply and the circuit breaker selection. The heater must not switch on without the fan running; the overheat thermostat and safety circuit must be intact.
Related (in Turkish): Fan coil electric heater · Burning smell · Tripping circuit breaker
Comparison of fan coil types
| Type | Typical use | Mounting position | Maintenance access | Watch out |
|---|---|---|---|---|
| Cassette | Offices, shops, meeting rooms, restaurants | In the suspended ceiling, panel visible | Easy (panel opens from below) | Condensate pump and float |
| Concealed ceiling / ducted | Hotels, homes, residences, prestige offices | In the suspended ceiling, with ducts and diffusers | Depends on the access panel | Duct pressure, access panel |
| Exposed ceiling | Offices, shops and workshops without suspended ceilings | Exposed on the ceiling | Easy | Visible pipes and drain |
| Floor-standing (cabinet/concealed) | Hospitals, schools, office façades | Under windows, on the floor | Very easy | Keep the front clear |
| Wall-mounted | Rooms and offices without suspended ceilings | Upper part of the wall | Easy (front panel) | Drain fall, board/remote control |
| Floor–ceiling | Offices, shops, classrooms, apartments | Vertical on the floor or horizontal on the ceiling | Easy | Drainage depending on orientation |
| Slim / decorative | Homes, hotel rooms | In front of a wall, under windows | Medium (narrow casing) | Capacity and fitting the valve set |
Which type suits you?
The right type is chosen by considering the structure of the space, how it is used and how maintenance will be carried out. The final choice is made during the survey based on the heat load and the pipework, but the following questions point the way:
- Is there a suspended ceiling? If so, and the void is deep enough, a cassette or concealed ceiling unit; if not, a floor-standing, wall-mounted or exposed ceiling unit.
- How important are aesthetics? If the unit should not be visible, a concealed ceiling or concealed floor-standing unit; for a visible but stylish solution, slim or decorative types.
- Is the space large and open? In open-plan offices and shops a 4-way or 360° cassette; a ducted type if several zones are to be served.
- Is there a window and façade effect? On façades with large glazing, a floor-standing unit under the window reduces the cold-wall effect of the glass.
- Is noise a concern? In hotel rooms and bedrooms the unit can be ducted and placed away from the room; units with EC motors run more quietly at low speeds.
- How will maintenance access work? Ease of maintenance should be considered from day one: access panels for concealed types, panel access for cassettes, and the filter removal direction in tight spaces.
- Is the system 2-pipe or 4-pipe? The existing pipework and thermostat must be matched accordingly.
Which brand offers which types?
The table below summarises the unit types listed on our brand pages as the types we service. Manufacturers' current product ranges may change over time; we also service types and older series that are not on the list.
| Brand | Unit types listed on our page |
|---|---|
| Aldağ | Cabinet floor-standing, Concealed floor-standing, Cabinet ceiling, Concealed ceiling, High-pressure ducted, 4-way cassette, 2- and 4-pipe |
| Üntes | Concealed ceiling, Cabinet ceiling, Cabinet and uncased floor-standing, 4-way cassette, High pressure, 2- and 4-pipe, AC and EC motor |
| Alarko Carrier | Concealed ceiling, High-pressure ducted, Cassette, Cabinet and concealed floor-standing, Wall-mounted, 2- and 4-pipe, AC and EC motor |
| Form | Concealed ceiling, High-static concealed ceiling, 4-way cassette, Wall-mounted and floor-standing, 2- and 4-pipe |
| Arçelik | Concealed ceiling (low and high pressure), Cassette, Cased and uncased floor-standing, 2- and 4-pipe |
| Ventas | Concealed ceiling, Concealed and cabinet floor-standing, High static, 2- and 4-pipe, AC and EC motor |
| Teknogen | Cassette, Floor-standing, Concealed ceiling, High pressure, Wall-mounted, 2- and 4-pipe |
| Genka | Concealed ceiling, High airflow, 4-way cassette, 2- and 4-pipe |
| Airplus | Cassette, Concealed ceiling |
| Termofan | Floor-standing / wall / ceiling |
| Daikin | 4-way and 360° round-flow cassette, Floor-standing, Floor–ceiling, Wall-mounted, Concealed ceiling / ducted, 2- and 4-pipe, AC and BLDC/EC motor |
| Carrier | Concealed ceiling, High-pressure ducted, 4-way cassette, 2- and 4-pipe |
| Systemair | Concealed ceiling / ducted, Ceiling, Cassette, Floor-standing and wall-mounted, 2- and 4-pipe, AC and EC motor |
| Mitsubishi Electric | Floor/ceiling (cabinet, uncased), Cassette, Medium-pressure ducted, Wall-mounted |
| Climaveneta | Floor/ceiling, Cassette, Ducted, Wall-mounted |
| Trane | Cabinet, Ducted, 1-way and 4-way cassette, Hygienic cassette, Wall-mounted |
| York | Concealed, Cased, Ducted, Cassette, Wall-mounted, 2- and 4-pipe, AC and EC motor |
| McQuay | Ducted, Cassette, Floor-standing |
| Dunham-Bush | Ducted, Cassette, Floor-standing |
| Aermec | Floor-standing / ceiling, Cassette, Ducted, Wall-mounted |
| Galletti | Floor-standing / ceiling, Slim, Cassette, Ducted, Wall-mounted |
| Sabiana | Floor-standing / ceiling, Cassette |
| CIAT | Cassette, Ducted, Floor-standing |
| Clivet | Cassette, Ducted, Floor-standing |
| Innova | Wall-mounted, Floor-standing, Ducted |
| Immergas | Floor-standing, Built-in, Wall-mounted, Ducted |
| LG | Cassette, Concealed ceiling, Floor-standing |
| Midea | Cassette, Concealed ceiling, Wall-mounted |
| Airfel | Cassette, Concealed ceiling, Floor-standing |
| Teba | Floor-standing / ceiling |
Brand names belong to their respective owners and are used only to indicate unit compatibility. YOİ Mühendislik serves all brands as an independent service holding the TSE Service Competence Certificate (HYB No: 12850).
Not sure what type your unit is?
Send us a photo, and we will work out its type, parts and maintenance needs together.
Frequently asked questions
What types of fan coil are there?
By casing and mounting position there are cassette, concealed ceiling (ducted), exposed ceiling, floor-standing (cabinet and concealed), wall-mounted, floor–ceiling (console) and slim/decorative types. By system they are divided into 2-pipe and 4-pipe units, units with AC or EC motors and units with electric heaters.
Is a cassette or a concealed ceiling fan coil better?
They serve different needs. A cassette provides even air distribution in large, open spaces without ductwork; a concealed ceiling unit is completely hidden and carries air through ducts to the required points. The choice depends on the ceiling void height, aesthetic expectations and maintenance access.
Which fan coil can be installed in a room without a suspended ceiling?
Floor-standing, wall-mounted, exposed ceiling and floor–ceiling console types do not need a suspended ceiling. If the area under the window is suitable, a floor-standing unit is usually the most practical solution; if a wall surface is suitable, a wall-mounted unit.
What does a high-pressure (high static) fan coil mean?
It is a version of a ducted fan coil whose fan is selected to deliver enough air against high air resistance, such as long ducts and many diffusers. If there is no duct or it is very short, a low or medium pressure type is sufficient.
Does the fan coil type affect maintenance costs?
Yes. Floor-standing, wall-mounted and cabinet types are quick to maintain because access is easy. Concealed ceiling units require the ceiling to be opened if there is no access panel, and on cassettes additional parts such as the condensate pump are checked. That is why maintenance quotes are prepared according to unit type and quantity.
Do you service every type of fan coil?
Yes. We carry out maintenance, fault repair, cleaning, installation and spare part replacement for cassette, concealed ceiling, floor-standing, wall-mounted, ceiling and all other types, independently of the brand.