Hot or cold water circulates through the battery depending on the needs of the premises. There can be two exchangers, one for hot water and one for cold water. The control system is responsible for letting water pass through one or the other. The water, hot or cold, is prepared in a technical room, using a boiler "Boiler (heating)") or a water chiller plant, respectively.

The pipes that link the fan coil units with the generators in the technical room can be arranged in two ways: with two and with four pipes. In the first case they have a flow pipe and another return pipe and with this system only one service (heating or cooling) can be provided at a time to all the devices in the network. In the case of four pipes, one pair will be a round trip for heat and the other pair will be a round trip for cold; Often these four-pipe fan coil units have two batteries, one for each service, but it is not absolutely necessary, since the controls are perfectly capable of operating one service or another according to the needs of the premises. This type of four pipes is mainly used in buildings where there may be areas that require heating while others require cooling (due to causes such as different sunlight, occupancy, orientation, etc.).

The pipe network that feeds the devices can be made with direct return or inverted return, such as hot water heating networks.[1]​.

Depending on the temperatures of the cold water and the relative humidity of the air-conditioned spaces, condensation will occur in the coils and must be discharged into the drain. The condensate would be collected in a condensate tray included in the device, with an outlet to connect to the drain and, if there are several fan coil units, a drainage network must be installed. If necessary due to the arrangement of the appliances, the drainage could be done using a pump and, if it were done to the general drainage network, an odorless closing device (normally a siphon) would have to be used to prevent odors from the network from reaching the inhabited spaces.

The power emitted by the fan coil units can be regulated by varying the fan speed. Some manufacturers achieve speed control by adjusting the taps of an AC transformer that supplies power to the fan motor. This would typically require an adjustment at the commissioning stage of the building construction process and is therefore set for life. Other manufacturers provide custom wound permanent split capacitor (PSC) motors with speed taps on the windings, set to the desired speed levels for the fan coil design. This can be done through a manual speed selector (stop-low-medium-high) that can be controlled by the user, or through automatic systems regulated by a room thermostat.

Speed ​​control of the fan motors within a fan coil unit is effectively used to control the desired heating and cooling output of the unit. A simple speed selector switch (off/high/medium/low) is provided for the local room occupant to control the fan speed. Typically, this speed selector switch is built into the room thermostat and is manually adjusted or automatically controlled by the digital room thermostat. Building energy management systems can be used for automatic control of fan speed and temperature. Fan motors are usually shaded pole AC or permanent split capacitors. Among the most recent developments are electronically commutated brushless direct current designs. While these motors offer significant energy savings, the initial cost and return on investment must be carefully considered.

Therefore, the battery receives hot or cold water produced in a thermal power plant and transfers the energy to the air and the fan propels it into the premises. Regulation normally consists of an internal thermostat, which takes the temperature of the room air at the return inlet, but a separate room thermostat can be installed. In certain buildings, regulation is done through an integrated control system, which moves the heat transfer inlet valve in the fan coil unit, following the indications of an ambient sensor, linked to the central control through a network.

Hot or cold water circulates through the battery depending on the needs of the premises. There can be two exchangers, one for hot water and one for cold water. The control system is responsible for letting water pass through one or the other. The water, hot or cold, is prepared in a technical room, using a boiler "Boiler (heating)") or a water chiller plant, respectively.

The pipes that link the fan coil units with the generators in the technical room can be arranged in two ways: with two and with four pipes. In the first case they have a flow pipe and another return pipe and with this system only one service (heating or cooling) can be provided at a time to all the devices in the network. In the case of four pipes, one pair will be a round trip for heat and the other pair will be a round trip for cold; Often these four-pipe fan coil units have two batteries, one for each service, but it is not absolutely necessary, since the controls are perfectly capable of operating one service or another according to the needs of the premises. This type of four pipes is mainly used in buildings where there may be areas that require heating while others require cooling (due to causes such as different sunlight, occupancy, orientation, etc.).

The pipe network that feeds the devices can be made with direct return or inverted return, such as hot water heating networks.[1]​.

Depending on the temperatures of the cold water and the relative humidity of the air-conditioned spaces, condensation will occur in the coils and must be discharged into the drain. The condensate would be collected in a condensate tray included in the device, with an outlet to connect to the drain and, if there are several fan coil units, a drainage network must be installed. If necessary due to the arrangement of the appliances, the drainage could be done using a pump and, if it were done to the general drainage network, an odorless closing device (normally a siphon) would have to be used to prevent odors from the network from reaching the inhabited spaces.

The power emitted by the fan coil units can be regulated by varying the fan speed. Some manufacturers achieve speed control by adjusting the taps of an AC transformer that supplies power to the fan motor. This would typically require an adjustment at the commissioning stage of the building construction process and is therefore set for life. Other manufacturers provide custom wound permanent split capacitor (PSC) motors with speed taps on the windings, set to the desired speed levels for the fan coil design. This can be done through a manual speed selector (stop-low-medium-high) that can be controlled by the user, or through automatic systems regulated by a room thermostat.

Speed ​​control of the fan motors within a fan coil unit is effectively used to control the desired heating and cooling output of the unit. A simple speed selector switch (off/high/medium/low) is provided for the local room occupant to control the fan speed. Typically, this speed selector switch is built into the room thermostat and is manually adjusted or automatically controlled by the digital room thermostat. Building energy management systems can be used for automatic control of fan speed and temperature. Fan motors are usually shaded pole AC or permanent split capacitors. Among the most recent developments are electronically commutated brushless direct current designs. While these motors offer significant energy savings, the initial cost and return on investment must be carefully considered.