Many thanks for the info.
I'll contact a local RGI to sort it out. Hopefully it won't take too long - I want some hot water/heating!
Bit disappointing that first Homeserve engineer re-started the boiler back on 4th Jan and ordered a new part but second engineer who visited today to fit...
I wonder if someone can offer their opinion.
We have a combi boiler which has an exhaust vent/flue through the external wall into the ginnel (passage-way through the terrace). There is a flying freehold/bedroom above the ginnel.
The boiler has been working fine for many years but has...