Not everyone is fortunate enough to have a diagnostics kit at hand or even the mi's for that matter when they attend a repair! Taking the case off a boiler is daunting for many who venture into repairing appliances and if you aren't doing it day in day out you soon get rusty! I'd agree that there is always the logical approach to fault finding but when you can't even recognise components or take the bleedn' case off, it gets a bit frustrating! Personally i think the diagnostic repair engineer is a rare breed in comparison to the part fitter! If your a repair engineer working for yourself it's a scary business at times, especially when faced with something you've never seen before, new or old!
The engineer the op had was a part fitter, and an expensive one at that! However there are times when we get it wrong, times when you go with your best guess! Through time those times become less and less but they still happen and will continue too throughout your career!
Regards pinpointing a fault! One of the hardest one to get right first time every time is one of the most common faults we come across with combi's, "hot water not getting hot enough!" So many variables!
I will never know it all and I will make wrong decisions, I know i will. Beauty is I'll continue to learn from them! 😀
fault finding is fairly new to me, but was it a boiler today which had broken down think it was the PCB as there was power to the boiler but no lights or nothing and fuse was fine, just got me thinking that if it was the fuse I wouldnt have any spares. What do you more experienced breakdown guys carry as spares for boiler breakdowns ?