A member of our family has a very newly installed Glow Worm 30SXi
boiler which cuts out for no apparent reason. The local fitter has
called in Glow Worm since it is under warranty.
The Glow Worm person has ordered a new gas valve.
Rather surprisingly, the GW man declared that he'd seen similar
problems on three other boilers in the area and that he believed it
was being caused by an additive which BG were adding to the gas so as
to reduce leaks.

Questions:
Is this plausible?
Do BG dope the gas in this way?
If BG do this, why will a new valve be any better?
How reliable are Glow Worm's boilers, (I'm planning to instal a
30HXi)?

TB