What is a Fan Coil Unit, what does it do & how does it work?
A fan coil unit is a relatively small piece of equipment that consists of a fan, a coil, and other components, that are used to cool or heat the air recirculating within a room. Some will also add fresh air to the space.
Typically, to operate in cooling mode, a wall or duct-mounted thermostat will note the space temperature is over setpoint controlling a modulating/on/off valve, the fan will blow air across the chilled water coil that is fed from the building central system, with the cooled conditioned air flowing back into the room, cooling the space.
Typically, to operate in heating mode, a wall or duct-mounted thermostat will note the space temperature is below-set point controlling a modulating/on/off valve, the fan will blow air across the heating coil that is fed from the building central system, with the heated conditioned air flowing back into the room, heating the space. The heating coil could also be an electric type.
They are pretty versatile and inexpensive, having options to be installed in concealed in ceilings, exposed [out of ceiling], or mounted vertically against a wall.
What types of fan coils are available?
We see that there are generally four [4] types of fan coil units, based upon how they are installed:
- Ceiling Concealed Ducted Fan Coil
- Exposed Horizontal Ceiling & Vertical Floor Fan Coil Unit
- Cassette Type Fan Coils
- Wall Mounted Fan Coil Units
Is a fan coil unit a terminal unit?
A fan coil unit can be considered a terminal unit. The short definition of a terminal unit is a piece of equipment or device installed within a system to manage and regulate primary air or water from a central source, chiller/AHU, before supplying a conditioned room/space.
What are the components of a fan coil unit?
An FCU will generally consist of the following components:
- Air Intake
- Filter
- Fan
- Chilled Water Coil
- Discharge
- Grille [Intake/Discharge]
- Speed Controller/on/off Switch/Thermostat
- Cased or Uncased [Casing around unit]
- Modulating/on/off valve[2-way valve/3-way valve]
2 Pipe System
A two-pipe [2] system is the most basic form of design and installation, and the unit will have 3 possible configurations - Cooling Only. A cooling-only FCU unit will only be supplied by chilled water to the coil, and these are usually found installed in spaces where no heating is required throughout the year. Usually found in hotter climates and small computer/server rooms.
- Heating Only. Similar to the cooling-only FCU system, the fan coil unit will be only supplied by hot water to the coil, and these are usually found installed in spaces where no cooling is required throughout the year. Usually found in colder climates.
- Cooling or Heating [Depending upon the time of year]. The cooling or heating option is entirely dependent on the time of year, in the summer, the central chilled water system will feed the 2 pipe systems and coil, whilst in the winter, it will switch over and be fed by the central heating system.
4 Pipe System
The four [4] pipe system uses two [2] coils in the FCU, one for cooling and one for heating. There are obvious benefits to using this system in that there are no changeovers required between seasons, and the system will automatically manage the space temperatures as required. The FCU is connected to the central heating and central chilled water system simultaneously, using the control valves on each system to provide correct temperatures.
Sendo Ceiling & Floor Type Fan Coil Unit
• Flexible installation, this type FCU can be installed by ceiling mounted or floor standing.
• Elegant cabinet. Centrifugal fan, 3 speed motor.
• Removable louver for easy maintenance, synthetic removable and washable air filter.
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