Fan coils and unit ventilators are excellent examples of single-zone
systems. These systems are available in horizontal ceiling mounted,
concealed, or recessed vertical floor mounted arrangements. These systems
are typically sized based on peak airflow, but the central refrigeration and
heating sources are based on typical loads.
These systems use in-room units contained in a common casing where
components such as a fan, heating and cooling coils, filters, controls and
often, in the case of unit ventilators, the outside/return air damper are
packaged. A common configuration uses low pressure, multiple speed fans in a
blow-through coil arrangement. A chilled water cooling coil is typical, but
direct expansion refrigerant systems are also used. The heating coil can be
hot water, steam or electric. For coils using water, two or four-pipe
systems are very common.
Where wall penetrations are not acceptable, ventilation can be supplied
by a separate system.
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