I remember the one I had used a sparkless motor, but I don't remember the model number. I bought some used ones from one of those 'grow show' gardening stores for pretty cheap.
http://www.elicent.it/inglese/axcmet.html (http://www.elicent.it/inglese/axcmet.html)
You can mount one of these somewhere on the wall, and run a tube along your ceiling and then to a grill mounted to a window to the outside. You can then use one of those flexible, but rigid type tubes for the side facing where the fumes are. This will give you adjustability. Some of these 'Elicent' fans move a lot of air and with all types and scales of gassing, I've never had a problem with it. They are pretty quiet, quite strong, and available in many different sizes.