I can only advise any retail to buy these fans from Helios. After a short time the first fan was broken. The audit at the factory lasted a legendary 7 weeks on demand then came a replacement device that held by just under 3 months. The error was the same, the Servie answered questions from the modular system that does not really fit the problem. It is claimed also that never somebody had a problem with the device and it thousands of times in ventilation systems ??? (There is a Kleinablüfter for bathrooms and storage rooms ....) was built ... well, I'm probably a real exception ... So stay away from fan and Helios!
