>>211970163It cools the room exactly the same even when pulling air through the ventilation shaft, though it did make me a bity dizzy when I tried it for the first time, I assume it's because it lowered air pressure in the room and that can be mitigated somewhat by leaving the doors to my room open.
Just one. It wouldn't be a problem otherwise because a 2 hose one doesn't pull air at all, whatever is thrown outside is replaced throught he other pipe.