First timer, please be gentle! I have a 3 year old CB28X boiler which has an intermittent hot water output. One plumber replaced the DHW valve diaphragm but this left a high pitch noise which the next plumber couldn't locate. Plumber 2 also performed a service but this has not cured problem. Diaphragm was in quite a state when it was removed, could small pieces of rubber be causing problem in heat exchanger? If so, is this an easy fix? Cheers, Belize95
