Multizone air terminal

摘要

The invention provides an air terminal capable of serving multiple zones with either variable volume, constant temperature air or variable temperature, constant volume air, or both, without any reheating of cold air. The terminal consists of a cold air plenum and a return air plenum. The cold air plenum is served with cold air from a primary cold duct. The air is introduced into this plenum through a damper which is controlled by a regulator for maintaining a constant pressure in the cold air plenum. The return air plenum is supplied with return air by a constant pressure recirculating fan mounted in the terminal. Constant volume, variable temperature air is supplied to the zones through thermostatically controlled mixing dampers which mix air from the cold plenum with air from the return plenum. A heating unit downstream from the mixing dampers selectively raises the temperature of the air provided to a zone. The heating is controlled in sequence with the mixing operation so that only return air can be heated. Constant temperature variable volume air supply is provided from the central terminal to serve zones that neither require heat or zones with controlled heat available from another source. In another embodiment, a hot air plenum is installed in fluid communication with the air in the return air plenum. A mixing damper mixes return air and hot air when the cold air dampers are completely closed off to provide heating to a particular zone.