I can't match that Sean but I too had problems with a ventilation fan in a darkroom many years ago.I was living in a rented house and could'nt carry out and major changes but wanted to ventilate the darkroom which was a huge utility room at the back of the farmhouse. This room had a large window at one end so I blocked it up with an equally large piece of inexpensive and thin plywood and decided to install an extractor fan. I cut a suitable hole adjacent to a part of the window that could be left open without creating any problems and imstalled the fan in the plywood fixed to the inside wall. It all looked great and reasonably tidy given that I am not the worlds most practical man. However, when I switched on the fan the large bit of cheap plywood sounded like a drum skin as a result of the vibration of the fan and the noise inside the darkroom was a bit loud and distracting so I gad to turn up the volume on the Led Zeplin tape and when I was printing the house sounded like Woodstock which got me into big trouble with the other half, but that's another story.