Hi Rusty Mac. Left the keys with my mate so will see if he comes around today. He’s not called me yet but he may have been around and just sorted it then again he may not in which case I’m probably going to go mental.
Thanks Totalshell. Not at home but don’t recall hearing the fan. I have a feeling this is the culprit though. Is the fan located at the top either near the flue or within the flue? If so there was a bit of a squeal coming from it after a few hours of use and just before shut down. Only really noticed it late at night when the mrs was using the hot tap and the demand clicked off. Will have a look at those and see what i can make out. Southern Electric did contact me a few weeks ago about their boiler repair program. Think it was about £15 a month of something similar.