ABSTRACT
In all-air central air conditioning systems, the only medium providing both sensible and latent cooling in the conditioned space is air. Central systems employ one or more air handling units which are served by heating and cooling equipment located outside the conditioned area. All-air systems are applied to buildings with a large number of zones that require individual control of space conditions. Variable air volume systems satisfy the cooling and heating loads of a building by varying the supply air volume to the conditioned spaces. In air and water air conditioning systems, both air and water are distributed to the conditioned spaces to provide heating and cooling. Air and water systems consist of a central air conditioning plant, a duct distribution system and a room unit. The primary air is cooled and dehumidified in the summer and heated and humidified in the winter at the central plant. The primary air fan coil system is very similar to the induction system.
