Boilers. Not built to last?

Our boiler just leaks out the relief valve, not a lot but enough. A new valve doesnt help

Plumber says the boiler is probably choked with calcaire leadin to excess pressure, but our kettle seems to have very little calcaire in it

Ok boiler is 6 years old, but even so, not cheap to replace.

anyone else had a leaky valve?

I dunno, we may have knackered the boiler ourselves inadvertently. It blew last september, after being well behaved for years, flooded the place. Found out that for years the old barn mixer tap was allowing the cold flow to pressurise the boiler! finally the valve triggered

Fixed that and was good til now, maybe its just worn out and leaky. Ill buy another valve, it may not work but its not expensive to find out

The water doesnt 'appear'hard and neighbours boilers seem ok

We had a Franco-Belge which was still working perfectly after 15 years when we swapped it for a wood-pellet set-up. It's now installed next door and still working. Check the hardness of your water with a kit and/or ask the neighbours. If water not hard then boiler shouldn't be furred up. We had the same problem as you have and fixed it with a new valve which I seem to remember was set to open at a slightly higher pressure, the original installer having erred on the side of caution.

Our boiler is a Viesmann and over 30 years old but they don't make 'em like they used to!