Flow optimised wall conduct with blower door certificate. Opens and closes without using external energy. The airtightness achieved in the blower door test reduces the heat loss almost to zero when the extractor hood is switched off.The energetic quality is drastically improved, because the flap has the same high tightness in both directions (negative pressure and positive-pressure measurement).
The hermetically sealed system is convincingly easy to assembly and requires no electrical connection.
Flow-optimised components and the absence of electrically powered accessory devices relieve the extractor hood and reduce noise.