Wall hung toilet frame height decides whether a pan fits under a window or needs a taller wall. This guide compares the Geberit Alpha 82cm and 98cm frames with Grohe’s 1.13m Rapid SL set, using KT’s current stock. It covers a worked cill example, pan projection, floor build-up and flush volume, plus the 6 litre flush cap in England and Wales, so you order the right frame, plate and pan first time.