A fan coil system is made up of many fan coil units. Each FCU, in turn, has a heating and/or a cooling coil with controls integral to the unit. Often the units are located in the space itself as a window or wall console unit, but it’s just as commonplace for the unit to be remote from the space it serves. Some ways to reduce energy use by these systems are:
1. Reduce airflow through the unit to the minimum to satisfy the space load.
2. Balance the flow of water to the unit to the lowest satisfactory volume.
3. Disable the unit fan when the heating or cooling load is minimal. The coils will continue to radiate some heat (cool), sufficient to handle a small space load.
4. Install an interlock in the unit to keep the system from heating and cooling at the same time.
5. Zoning a four-pipe system into a two-pipe system will save on changeover losses when switching the mode between heating and cooling functions.
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Excerpt from Energy Conservation Projects.