On Tue, 12 Apr 2016 08:56:45 +0100, Chris Bartram
wrote:

On 12/04/2016 08:42, wrote:
Our hot water began to play-up when the boiler was just over a couple of years old and the problem continues to this day (3 years down the line). Annoyingly, we only changed the old one (10 year old Vailant combi) after repeated attempts by BG service people, including replacement of most major component, failed to fix exactly the same problem.


So the only common factor appears to be the high water pressure.