Hi, I have noticed the stone above the flue from my boiler has syarted to crumble and leaving sandy deposits inside the flue and also all around the back door; I have looked at the rest of my wall away from the flue and it seems to be fine; Do I need to paint the wall with something or does my flue need some kind of lid/chimney to divert the fumes so that they are furtheraway from the wall.
Thanks
