If a Ventalation moter is a large belt drive type a soft start goes a long way to saving berings and belts. If the ventelators stop and start alot this is even more of an issue. I have a building that has a air handler with no soft start. The blower only starts once a day but the jirk on the belts and berrings can be heard in the parking lot 100yards away. The customer is not the type to spend money on somthing that is not broken though. This motor is 60hp and the machine moves as much as 50,000 CFM. Granted this is a large machine but even a small blower like a two to five hp would benefit. Also if you have sensative equipment in the building the surge from a large moter starting can have a negative effect. The selling point for a coustomer for my area is our utility company charges extra for power demand spikes. The starting amp draw is reduced greatly with a soft start.

We specify VFD's frequently for energy savings and capacity control.

The added benefit is that we also get a 'soft-start' from the VFD. Although the application depends on cost and system design we have used VFD's on motor's as small as 3hp.

Sometimes the electrical utilities may insist on soft starts once a motor gets to a certain size.