contain openings above the sash, in addition to an airfoil sill that will redirect the airflow as the sash is closed. The bypass openings reduce changes in face velocity to a narrow range by keeping the area for airflow equal (within the limits of the bypass) as the sash is moved up or down. Therefore, face velocities do not reach the detrimental levels often seen with conventional hoods. For this reason, bypass hoods hold a major share of the market today.
Recent models of bypass hoods, ca