A fan strong enough to get the job done is going to be the loudest thing in your brewery. That alone, all else being equal, was enough to make me "slay" the steam. In theory, if you could throttle the exhaust perfectly and suck from directly above the kettle, you could vent exactly the right amount of volume such that you don't create negative pressure in the room. The truth is though, at that rate a lot of the steam would condense in your duct work.