Fans that can be controlled with Variable Speed Drives (VSD) or have in-built speed control will display a Speed Slider Bar in the Performance Data Panel. The speed can be adjusted using the slider or by typing a frequency into the accompanying box. This will automatically calculate the actual performance and sound data at the new speed.

You can also select a fan for two-speed operation where a VSD will be utilised for low speed (Adjustable Pitch fans only). Under the “Variable Speed (VSD)/Belt Drive” section of the Advanced Select Fan tab, enter the air flow and pressure for the fan at low speed, and the selected fans will have data at both speeds, using a VSD at the low speed.