anybody ever come across carbon deposits blocking a gas valve? apparently caused by a chemical reaction between the gas and a low grade copper. this is coming from a vaillant engineer visiting a boiler I fitted that is still under warranty.
Thanks for reply. This is on 22mm copper leading to a glowworm flexicom les than 12 months old. Gloworm/ vaillant wont touch boiler now until all gas pipe changed leading to boiler. Sounds like a cop out to me.
It was caused by British gas adding a smell to the gas. This chemical caused the reaction.
Seen it loads. "Black dust, fibres, black iron oxide" heard them all!
Very common, not your fault not the manufacturers fauly. Ring national grid and they will hover the main.👍