Ventilation controls allow you to use your bathroom exhaust fan for exhaust ventilation. The timers and controls have a variety of functions to suit your ventilation needs. Programmable timers let you schedule ventilation in 20 or 30 minute intervals throughout the day. Speed controls allow you to designate the fan speed and the override function enables you to use the fan on full speed for a certain amount of time. All of the timers are compatible with standard residential wiring.