Air Distribution Fan Recycling Control

An system for controlling the operation of the circulating fan of a closed central air conditioning(CAC) system is disclosed. The system periodically activates and deactivates only the circulating fan after a preselected delay time from the normal running of the cooling and heating modes of the CAC system. The preselected delay time is adjustable based on non thermostat parameters and include parameters such as room volume size to be ventilated and the number of occupants in the room. The control can periodically distribute and mix ventilation air or spot-conditioned (humidified, de-humidified, or cleaned) air while the CAC system is not running in the heating, cooling or constant fan modes. The cooling and heating modes of the CAC system operate independently of the fan recycling control