Bosch Downdraft

Outside / Ducted - The polluted air rises, is pulled up by a fan, passes through filters, and is exhausted outdoors through a metal duct. High BTU gas cooking equipment should always be ducted to the outside of the home.

Inside / Non-Ducted - A fan draws the polluted air through filters and then recirculates the cleaned air back into the kitchen. Non-vented hoods circulate the air through charcoal or other filters fitted in the house and then let out purified air for recirculation.

Ducted  or Vented hoods