I recently got a wall hung Aquia installed to save room (which it didn't after all because we had to move a wall out to fit the tank!!) and it doesn't flush properly. Regardless of whether it's the big flush or the small flush, neither of them cause the water to completely exit the bowl. The water goes down until it reaches a few inches above the drain and then just stops going down anymore. Please see video:
The Toto engineers think that the toilet isn't connected properly to the vent stack, but our contractor checked that and it seems to be fine. Has anyone else had this problem and how did you fix it?
How does it work when you dump a five gallon bucket down?
Here is a picture from the Gerberit installation manual. The Gerberit is very similar for it's installation.
The Gerberit Installation
The TOTO installation