Abstract: The invention is directed to a detection system for detecting object presence in a detection zone and always detecting object departure from the detection zone so as to provide an object presence detection zone output signal indicative of zone occupancy. The system is comprised of a main system control unit mutually responsive to both an object presence signal from the zone and an object departure signal form the zone to provide the object presence detection zone output signal "ON". The object presence detection zone output signal remaining "ON" for a preset time period, which preset time period is retriggered "ON" as long as presence of an object in the zone is detected. The object departure signal causes a discrete moment of departure time delay signal that causes the object presence detection zone output signal to mm "OFF" when no object presence is detected in the zone during the discrete moment of departure time delay.

Abstract: A bi-directional airflow controllable system for controlling flow of air through an air circulating system to at least one zone an air temperature of which is to be controlled is coupled to an airflow duct to aid or oppose airflow throughout the duct and the system to the zone. The bi-directional airflow controllable system includes a fan positioned to interact with air moving through the system and the duct. The fan is coupled to a motor to be energized to drive the fan in a forward or reverse direction. The fan when driven by the energized motor in a forward direction creates air pressure from the fan to oppose the flow of air from the airflow duct. The fan when driven by the energized motor in a reverse direction aids the flow of air from the airflow duct. A bi-directional airflow control unit is electrically coupled to the motor.