ZONING (see section 17.0) Zoning alternatives Constant Volume (CV) Individual units Single zone Zoned Multizone Constant Volume (CV) Variable Air Volume (VAV)

COMPONENTS OF AIR-HANDLING UNITS (Additional information) Heating coils: Heating coils are heat exchangers between a heating medium and the air stream. Heating mediums available for heating coils are steam, hot water, or electricity. Steam and hot water coils consist of copper tubing surrounded by sheets of corrugated fins that guide air toward the tubing to maximize the transfer surface in contact with air. Steam or hot water must be produced by a boiler and conveyed to the AHU by piping. Cooling coil: Cooling coils carry either chilled water or refrigerant. In some AHUs, same coil is used to carry both hot and chilled water at different times according to need. A coil carrying refrigerant serves as the evaporator to a direct expansion cycle. Drain pan enclosure: Collects condensate from a cooling coil. Constructed of heavy galvanized iron or stainless steel; insulated to prevent the enclosure from sweating. Other accessories: (1) mixing boxes that combine fresh and return air, (2) Humidifiers for injecting water vapor into the air stream, and (3) dampers for controlling air flow.