I am looking to get a few quotes for a new combi boiler (worcester 30cdi probably) and wanted to get my facts straight to ensure i don't get fed incorrect information. I want the new boiler to be installed on a external wall in my attached garage with a vertical flue as there is nothing above the garage. The gap between the external garage wall and next doors wall is only about 30cm and i wanted to confirm that if i have a vertical flue then the clearance to the side is irrelevant and i just need to meet the reqts for clearance around the vertical flue. I've checked the 30Cdi installation guide and believe i'm correct but a local plumber reckons i still need 600mm clearance to the side (i'm dubious about his credentials but he happened to be around so i asked)