In the planned kitchen the space for the extractor hood is already marked. The decision between recirculation (Umluft) and extraction to the outside (Abluft) is still treated as a fitting detail, however. For an existing building more is at stake than the appearance: which operating mode suits the existing situation and how must it be professionally planned?
Two air routes, two different starting points
The Umweltbundesamt describes recirculation as a circuit: air is guided through grease and odour filters and returned to the kitchen. An extraction hood leads the sucked-off and filtered air outside via a system. Which type is suitable depends, according to the consumer information, on both the structural circumstances and the use. [HAUBE]
This is a decision about a system in the room. A appliance width or a general performance figure does not answer it completely. Begin therefore with the existing kitchen plan, known exhaust routes and the question of how the room is actually to be used. An old wall penetration is information for the assessment and not yet a confirmed connection option.
Explicitly state existing combustion appliances
The UBA points out a particular danger with extraction hoods in connection with room-air-dependent combustion appliances: if incoming air does not sufficiently compensate the resulting negative pressure, exhaust gases can enter the dwelling. Whether safe operation is possible should be assessed by a specialist. [HAUBE]
Therefore state any corresponding existing installations during the planning and ask for the necessary coordination. This article does not prescribe its own safety solution. It does not assert that a window contact or any other single component is a sufficient measure and does not offer a self-test. A report of experience from another flat also does not replace the assessment.
Discuss daily operation concretely
In the fictional example a separate kitchen is to become a more open kitchen-living area. The owners want to hold conversations in the living area while cooking. They therefore ask about the intended operation of the hood, the associated noise specifications and the works that the respective variant requires on the building.
Also ask questions about filter maintenance and spare parts based on the specific model. According to the UBA information the odour filter of a recirculation hood must be replaced regularly. [HAUBE] This article does not set an interval for a specific appliance. Have the intended effort and the appropriate manufacturer instructions explained before you consider the operation permanently settled.
Order a coordinated variant
Record the exact model, the confirmed operating mode and the associated planning assumptions together. Ask which specialist assessed the existing connections and the intended execution. If prerequisites remain open, they belong in the follow-up questions before the binding selection.
This article is a preparatory aid for Germany. It does not confirm that an opening in an external wall is exempt from approval nor the suitability of an existing duct. The aim is a professionally justified system decision in which building, everyday cooking and appliance characteristics are considered together.