I’d appreciate some help, please, to clarify a couple things about properly ventilating a darkroom. Thanks in advance to all ~
The space:
11’ x 13’ ground floor room opening onto 5’ x 7’ alcove. The doorway from outside is along the 11’ wall, which has an adjacent eye-level, sliding window, 14” x 34”. (Because of the sliding action, the actual window opening is about 15” wide.)
The alcove, where the darkroom will be, opens into the opposite corner away from the front wall. There’s a second, sliding window at eye-level here that’s approx 22” square (8” wide opening). The sink will face this window.
So, I’m thinking to put a Doran 400 CFM fan in the window in the larger room to draw fresh air in, and a passive air outlet through a light louver in the window above the sink in the alcove to release the fumes outside while maintaining a positive pressure. (I've been told positive air pressure is important to reduce the amount of dust in the darkroom.)
Or should it be the other way around? with the passive, louvered inlet of fresh air flowing into the larger room and the fan serving to exhaust (extract) the fumes above the sink and out the alcove window?
Which is correct?
I think what’s confusing me is the idea of positive pressure necessarily being created by a stronger in-flow of air relative to the fumes leaving the space.
Also appreciated would be tips on how to keep the fan area facing the outside dry, as well as alternates to the Doran fan and louvers as needed. And is some type of additional air filter on the intake side needed as well?
Many thanks for your kind advice and shared experience!
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