Indoor air quality control for constant volume heating, ventilating and air conditioning units

摘要

A system for circulating ventilating air in a space includes a supply air chamber configured for communication with a supply duct, a return air chamber configured for communication with a return air duct, and an outside air chamber configured to receive outside air from an outside air intake. The outside air chamber includes an outside air damper having a plurality of settings for varying outside air flow volume in the outside air chamber. The outside air damper establishes a predetermined relationship between each outside air damper setting and the outside air flow volume. The outside air damper establishes each setting in response to a damper control signal. The system further includes a mixed air plenum in communication with the return air chamber and the outside air chamber and a fan positioned between the mixed air plenum and the supply air chamber, the fan supplying a constant volume of air to the supply air chamber in response to a fan control signal. The system further includes a controller coupled to the outside air damper and the fan for providing the damper control signal and the fan control signal to establish a minimum outside air flow volume to the mixed air plenum.