I intend installing an Aqualisa digital shower in my loft. . My water pressure is 5 bar. Flow 14l./min. with a combi boiler. As I fancy a square shower head from the ceiling, and would like as much flow of water as I can get . Should I then install the largest square head I can ? Or would a medium one be better as regards flow and pressure. So what size and type is recommended ? Thank you for any advice and suggestions Heinekinuk.