This 5 step speed controller by RUCK is perfectly suited for controlling exhaust fans without unpleasant humming.
Unlike with conventional dimmers, with a 5 step speed controller, the fan is controlled in stages and not completely variable. This is due to the different operation mechanism of the two types of devices.
This has the disadvantage that the fans are not seamlessly adaptable to the required performance, for example by means of a thermostat, when using a 5 step dimmer.
At the same time, this mode of operation in steps also offers an invaluable advantage: The connected fan doesn’t emit hum when the speed is reduced. Step controllers are therefore the method of choice when minimum volume is of maximum importance.