Greyduster
Vaillant are good boilers. DD has a Worcester Bosch and they have had no problems with it. I changed the system in this house to a Baxi combi system in 2023 because I thought it would be more economical and it is if I didn’t have to balance it against the water I waste before hot comes through to the taps. There has been a pressure issue with it every year which I hope has now been solved, but I won’t know until the CH goes on again. I just don’t think that boilers, like most things, are as well made these days as they used to be.
I think your last sentence sums it up, it seems all appliances now are designed to fail within 10 years.
My floor-standing oil-fired boiler was installed in September 1986. It’s serviced yearly, with a gentle touch in deference to its age, and it has seldom missed a beat in the many years I’ve lived here. I’m lucky to use a wonderful family firm of heating engineers, the current “elder” learned the trade from his own father, and now the next generation are proving equally commited to brilliant customer service, and carefully repairing instead of leaping to recommend replacement.
I dread having to get a modern condensing boiler, though I know it should be more efficient I won’t live long enough to recoup its cost in lower oil consumption.