There isn't a vent, I think. We remove our chicks as soon as they look dry enough, which seems to keep the humidity down. We took our last four out, still wet, and stuck them straight under the infra red lamp to dry out that way as, like your experience, they were sopping and it was really humid! When did you get yours? Like Dizzycow, we brought ours last April and it packed up when we got it out to start hatching again this year and it went belly-up. As she says, faulty adaptor and the brinsea help desk are very helpful.
BTW, sounds like you got your humidity water levels right, don't listen to anyone else on here who hasn't got this incy WRT what humidity levels are needed. We follow the instructions by the letter and have achieved 90% hatch rates this year (although the last three hatches have been 100%).
