My Vaillant GB 242/2 has just started making a noise when it attempts to strick. System runs up and even makes hot water but the boiler is now making a loud buzz sound at the point of attempting and sucseeding to fire. Does any one know which part needs replacing, the gas valve complete or just the solenoid?

Paul 42, March 2009

Sounds like the solenoid,but it could work like that for ages.Its not dangerous just annoying.

Tony S, March 2009