I have a combi boiler and run our shower from a mixer tap on the bath. Recently the hot water flow rate in the shower has reduced significantly. The boiler man checked the boiler but said it was fine and said something about the problems with using mixer taps for showers when running off a combi boiler. He said that for some reason sometimes the mechanism within the mixer tap gets messed up and effects the flow rate. To be honest thois is the first I've heard about this but there you go.. and I'm not a plumber. Can anyone enlighten me as to what to do. Should I get a new tape, fix the exisiting one (if it can), have a power shower installed?