In general, active charcoal filters are being used whenever exhaust air operations are not possible for structural reasons and the exhaust air cannot be vented into the outside air. In this case, the vapors are captured over the cooking surface and purified by a grease filter. Prior to returning the purified air into the room, the active carbon filter also removes any odors. The new patented GUTMANN re-circulation process utilizes the highly effective extrusion process involving mineral coal to manufacture an active charcoal filter honeycomb element that can be regenerated in any household oven. Its large surface guarantees the absorption performance. Thanks to the laminar streams in the honeycomb channel, the air resistance that develops is only minimal and the noise level is greatly reduced.
In conjunction with this new development, a variant of the external air re-circulation version can also be implemented.