External blowers are mounted to an exterior roof or wall. Because these are the furthest away from your cooking space, they are often the quietest option whenever it comes to blowers. Due to their relative distance from the air they are trying to exhaust, external blowers are generally more powerful, and have a higher CFM rating. For optimal results it's best to make your ducting straight and short, using as few turns as possible.

Internal blowers are located inside of the vent hood itself. Because of its location, these are generally the noisiest of the blower options, but they are also generally the most cost-effective route.

Inline blowers are located about half-way between the vent hood and the opening to the outside, inside of your duct work. This option is not as noisy as an internal blower, but not as quiet as an external blower. It cuts down on the noise like an external blower, while being protected from elements like an internal blower.