One of the reasons I have seen for not routing the condensate from an extractor fan outlet into the soil stack (at a point above all sinks/toilets/etc that drain into the stack) is that smells would come from the stack into the room containing the extractor fan. I can see the logic in this but what appears contrary to this is that I have seen AAVs fitted in locations within a room (eg loft conversions etc) but there is no obvious problem with smells. The AAVs probably have a better seal on the one way vent in some way but that, to me, begs the question why there is no better seal available for extractor vents. I have some thoughts on this but would like to get some input that is not biased by my own ideas. Thanks in advance.