Hi. Could anybody tell me what the legal length is for a boiler flue. My sister is having some bother. She lives in a council property and 2 years ago they condemned her boiler and flue due to the flue wasnt at the right angle. They put in the new inspetion hatches and raised the flue slightly. She now has a crack in the flue. But the guy who inspected said he wasnt sure what the legal length was for a flue and at 8ft her flue looked to long.so can anybody help me as we still have no idea the correct length.