customer called me , wants me to go over to fit a new bathroom, he wants a shower pump fitted, the hot water cylinder is in the room next to the bathroom so at about same level as shower valve would be, and I take it that the header tank is in the attic,, do I need a positive head or negative head pump? any recommendations on pressures or manufactures? ill go down the route of an Essex flange. also does the pump need to be a certain height etc? thanks