Here's my anecdata from building one. The box fans are not good at running the hours that a commercial unit does. Eventually the bearings start failing and even

Here's my anecdata from building one. The box fans are not good at running the hours that a commercial unit does. Eventually the bearings start failing and even smelling bad. And they are louder and often can't run at a comfortable noise level. So for longer term use you might want to find a type of fan that's better than a cheap box fan or find a decently priced commercial unit.