We had a new semi-commercial (100kw) boiler installed over the summer but have been encountering problems this weekend. This evening we've lost all heating and hot water and we've been seeing dark grey smoke from the exhaust flue. I'm assuming we're having a problem with the air/fuel mix and correct burning so I'll get an engineer out tomorrow to have a look at the injector/ filters. However I've also noticed that the flexible pipe from the burner unit to the flue on the top of the burner is crushed/ crumpled where it joins the flue. What sort of issue can cause this and should I get the engineer to replace this aswell? Honestly we seemed to be cursed when it comes to boilers!! Thanks if anyone can help!