low tech ventilation technology without a ventilation duct

With the connector fan, Erich Keller AG has developed a ventilation technology which silently exchanges air between the corridor and the room. Connector fans enhance doors and walls into a ventilation element which does not require the tedious installation of ventilation ducts. The result is an extremely efficient and demand-oriented ventilation. This ventilation technology is the easiest solution to implement, not only for new buildings, but also for conversions or refurbishments.

Erich Keller AG - Swissklinik Pfaeffikon SZ, Connector fan smoke test - YouTube
Erich Keller AG - Haffter Weinfelden, Connector fan smoke test - YouTube