Abstract: An air recirculator/mixer system for easy adaptation to a conventional dryer system. A programmable control unit operates according to a predetermined program scheme, in response to elapse time and temperature sensor inputs to drive a motive means and adjust fresh air and exhaust dampers of the recirculator/mixer system. Damper adjustments are made during a drying cycle in response to the accrued time and temperature data processed by the controller.

Abstract: In a tumbler type of dryer, particularly for large capacity commercial and institutional laundries, a heating control system is provided which is responsive to the rate of increase of temperature of hot air leaving the dryer. When this temperature increase exceeds a preselected rate the dryer control system is automatically instructed to shut off or diminish the hot air supply, as well as the tumbler operation if desired. Thus energy is not wastefully consumed after the laundry is already dry; on the other hand, the dryer does not prematurely shut down while laundry is still damp, whereby the dryer must be started up again and energy again is unnecessarily wasted. Different settings are selected in accordance with the characteristics of the type of laundry being processed.