Multi-Speed with Time Delay allows you to select the proper CFM settings to satisfy ASHRAE 62.2 continuous ventilation requirements. The fan runs continuously at a pre-set lower level, then elevates to a maximum level of operation when the wall switch is turned on, or when the SmartActiona® motion sensor or condensation sensor module is activated. A high/Low delay timer returns the fan to the pre-set CFM level after a period of time set by the user.