I bought the Doppelzirkulator to distribute the warm air furnace of the high ceiling in the room. At first I was a little skeptical and a little put off by the size. With a height of about 75 cm, it is not exactly small. But it actually works. The warm air furnace under the blanket is felt throughout the room. The advertised in a catalog volume is low ("can even be operated in rest rooms") I do not share. The device is clearly audible even at the lowest level. But since I do not operate the device permanently, it is not quite so bothersome. I can especially picures the Doppelzirkulator, but not because of its size and the volume for continuous operation. The test for the operation in the summer is still pending.