Quote Originally Posted by blansky
Some people just put an air vent in the door for the inward flow of air.

http://www.calumetphoto.com/ctl?ac.u...+vent&x=18&y=4

Michael
Yes, I know... But my door is heavy steel and is under the ground level (the darkroom is in the basement) so I think I've better way to drill a 4" hole in the concrete...
Anyway, thanks Michael !