What does fan coil mean?
The word fan coil comes from the English words fan (blower) and coil (heat exchanger coil). The name also describes what it does: the fan draws in room air and passes it through a coil cooled or heated by water, then returns the conditioned air to the room.
Although it looks similar to a split air conditioner from the outside, it works differently. A fan coil has no compressor or refrigerant; the cooling and heating energy comes from the water in the pipes. That is why fan coils do not work on their own but together with a chiller, boiler or heat pump.
How does a fan coil work?
- Cold water from the chiller (typically around 7 °C) or hot water from the boiler enters the fan coil's coil.
- The fan blows room air through the filter onto the coil; the air exchanges heat with the water.
- In cooling, moisture in the air condenses on the coil and drains away through the drain pan.
- The thermostat controls the fan speed and the valve according to the room temperature.
Parts of a fan coil unit
- Coil: a heat exchanger made of copper tubes and aluminum fins
- Fan and fan motor: mostly a 3-speed AC motor; in newer units, an EC motor that uses less electricity
- Filter: protects the coil and the room from dust; it is the part that needs maintenance most often
- Drain pan and, when needed, a drain pump: removes the condensate
- Valve and actuator: A 2-way or 3-way valve opens and closes the water flow
- Fan coil thermostat: temperature set point, fan speed and mode selection
Fan coil types
| Type | Where it is installed | Where it is preferred |
|---|---|---|
| Wall type fan coil | On the upper part of the wall, like a split indoor unit | Existing buildings, single rooms |
| Floor type fan coil | Under a window or against the wall; cased or uncased | Offices with glass facades, hotels, hospital rooms |
| Ceiling type fan coil | Suspended from the ceiling, exposed | Large areas without a suspended ceiling |
| Cassette type fan coil | Inside a suspended ceiling, 4-way air discharge | Offices, shops, meeting rooms |
| Concealed ceiling (ducted) fan coil | Inside a suspended ceiling, with a vent and ductwork | Hotel rooms, corridors, spaces that call for a clean look |
Support for fan coil maintenance or faults
Tell us the number and type of fan coils and the building; we will prepare a maintenance plan and a quote.
Difference between 2-pipe and 4-pipe fan coils
In a 2-pipe system, a single supply and return line comes to the fan coil; the same line carries cold water in summer and hot water in winter. In a 4-pipe system, cold and hot water come through separate lines; one room in the building can be cooling while another is heating. For a detailed comparison, see our article difference between 2-pipe and 4-pipe fan coils.
Fan coil or air conditioner?
Because a fan coil has no compressor in the room, it is quiet and no refrigerant is distributed through the building. On the other hand, it requires a central chiller and water installation; that is why it is generally used in large buildings. In small buildings, split or VRF systems can be more practical. We covered the choice in our article VRF or chiller.
How is fan coil maintenance done?
The core tasks of fan coil maintenance are filter cleaning or replacement, coil cleaning, clearing the drain pan and line, fan and motor checks, and valve and thermostat tests. A dirty filter both reduces cooling and strains the fan motor; a blocked drain is the most common cause of suspended ceiling water leaks. Details are on our fan coil maintenance page and in our article filter, coil and drain. You can estimate how many fan coils your room needs with the fan coil quantity calculator.
Frequently asked questions
What is a fan coil for?
A fan coil is an indoor unit that cools or heats room air using cold water from a chiller or hot water from a boiler.
Does a fan coil have a compressor?
No. A fan coil has no compressor or refrigerant; it takes its energy from the water in the pipes. The central chiller does the cooling.
Does a fan coil both heat and cool?
Yes. In a 2-pipe system, cold or hot water arrives through the same line depending on the season; in a 4-pipe system the two lines are separate and different rooms can be heated and cooled at the same time.
What does a fan coil thermostat do?
It measures the room temperature and controls the fan speed and the water valve according to the set point; the mode (cooling/heating) is also selected from the thermostat.
How often should fan coil filters be cleaned?
It depends on usage and the dustiness of the environment; in heavily used buildings, cleaning or replacement every few months is generally recommended.