How does a chilled water fan coil unit work?
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Introduction
A chilled water fan coil unit (FCU) works by transferring heat from the air passing over the internal heat exchanger to the chilled water passing within. Cold water is supplied by a chiller unit, or reversible heat pump, which is installed in a central plant room or on the roof of a building. Water within the distribution network is cooled to between 6 and 10°C.
Next, the chilled water circulates through a pipework distribution system to the heat exchanger (coil) within the fan coil unit. Fans within the unit then draw air over the exchanger containing the cold water cooling the air, which is finally dispersed into the desired space to provide the occupants or building users with comfort cooling.
Control types for chilled water fan coil units
An FCU, as standard, will come with fans and valves but will require controls to maintain the specified temperature for a space. There are both internal controls and external controls.
Internal fan coil controls
These continually monitor the temperature within a space, adjusting the fan speed as well as opening and closing the valves to maintain the required comfort levels. This helps the system to be more efficient by continually making small adjustments to maintain the optimum environment for the user, whilst ensuring the unit is never overworked.
External fan coil controls
These are wall-mounted units that provide the occupants with the ability to adjust temperatures to achieve desired comfort levels.
Chilled water fan coils units are an effective alternative for refrigerant based systems. They provide energy efficient comfort cooling to commercial and residential buildings and are available in a range of installation options to suit the specific space requirements of a project.
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