Just been to collect the part, and it appears that Vaillant gave me the wrong ****ing part number, so that was a waste of about 20 phone calls and 4 hours nonsing around. Grrr.
If anyone knows the correct part number for the elbow-shaped auto bypass valve (aka spill valve) for this appliance, then you could gain me a very grateful client.
Failing that, I'm going back and I'm gonna get medieval on its ar*e.
It'll have bypassed its last by the time I've finished.
Firstly, there wasn't only one helpful response, since I was PMd with more help, but ultimately I suspect corgiman is correct, because Vaillant were closed/busy for most of the holiday period, and I couldn't find an open merchant whose breakdown charts included the elusive spill valve.
In the end I've got the correct answer from Vaillant (150216), but in the meantime have implemented a workaround that's a cunning as a fox whose just been made Professor of Cunning at Oxford University.
I hope that answers your question. If you have any more, please post them to:-
Pointless Questions
Department Numpty
BBC TV Centre
W1A R5E