With Silver Swith you finally have the free choice for the exhaust, because the system can motor vary between circulating and exhaust air. Thus, an extractor hood can be used with exhaust air in summer, directly exhausting all annoying odours to the outside. In winter, you can switch to circulating air, thus not losing valuable room warmth. The system can be used for new installations as well as for the retrofitting of existing extractor hoods.