some advice needed, I could do with some input on a fanned flue outlet being 200 mm away from a cooker hood vent, the vent has flaps which close when not under positive pressure from hood. would this be classed as safe due to the flaps closing when cooker hood not in operation. I respect the fact maufactures instructions and bs expect 300 mm but I am a suing this would be in an open vent or window which is not under any pressure. any help would be great