A forced air conditioning system includes supply and return air plenum, an air treatment device, first and second air return dampers, first and second sensors, and a controller. The plenums communicate with first and second rooms and the treatment device is adapted to condition air when activated and not condition air when deactivated. The air return dampers are adapted to isolate the respective first and second rooms when closed. The sensors are located in the respective first and second rooms and are configured to detect a condition of the air. The controller is configured to receive condition signals from the respective sensors, compare the signals to a preprogrammed air condition threshold, and output a command signal to close one of the dampers to substantially equalize the air condition between rooms when the preprogrammed air condition threshold is met, and the air treatment device is deactivated.