Advice for installing louvers and a fan for a darkroom shed?

[Doremus Scudder]

Haven't read the entire thread; just thought I'd chime in with my solution.

The Doran light-tight louvers I bought were obviously just for one wall; the inside. No provision for outside.

What I did was to frame a 12x12-inch box in the wall, using 2x4s along with sealant (but you should use whatever width your shed is framed) so I had an air-tight box. The Doran louver went on the inside darkroom wall (just drywall and paint), a couple of 12x12-inch furnace filters went inside the framed box, and I installed metal louvers on the outside wall. My darkroom is adjacent to a basement room, so I didn't have to worry about weather-proofing the outside louvers. You may have to get louvers that have angled grill-work to shed rain and/or mount them under the eaves, etc. to ensure that water can't get in during a storm.

The other half of the system is an exhaust fan that takes air from above the entire length of the 10-foot darkroom sink. As that air exits, fresh air is pulled in through the filtered louvers so I have fairly clean air coming in. I have air filters working inside as well when dealing with film.

Pulling in filtered air and having it exhaust through the louvers is another idea, but I found my solution more practical for my needs.

Hope this helps,

Doremus

[m00dawg]

Haven't read the entire thread; just thought I'd chime in with my solution.

The Doran light-tight louvers I bought were obviously just for one wall; the inside. No provision for outside.

What I did was to frame a 12x12-inch box in the wall, using 2x4s along with sealant (but you should use whatever width your shed is framed) so I had an air-tight box. The Doran louver went on the inside darkroom wall (just drywall and paint), a couple of 12x12-inch furnace filters went inside the framed box, and I installed metal louvers on the outside wall. My darkroom is adjacent to a basement room, so I didn't have to worry about weather-proofing the outside louvers. You may have to get louvers that have angled grill-work to shed rain and/or mount them under the eaves, etc. to ensure that water can't get in during a storm.

The other half of the system is an exhaust fan that takes air from above the entire length of the 10-foot darkroom sink. As that air exits, fresh air is pulled in through the filtered louvers so I have fairly clean air coming in. I have air filters working inside as well when dealing with film.

Pulling in filtered air and having it exhaust through the louvers is another idea, but I found my solution more practical for my needs.

Hope this helps,

Doremus

It does thanks!! Yeah for a design like this I was thinking about just cutting a hole and putting a dryer vent on the outside (with a screen perhaps) and then optionally putting some sort of filter material inside as well. Given the discussion about negative vs positive pressure, the concern with the "pull" configuration, even though that's what the Doran manual shows as well, is the air will come in via the easiest path which might not be the filter (I suspect it'll be the floor). On the other hand, if I need to extract chemical fumes, I'll want that to be the priority such that having the exhaust basically right above the chemical trays seems like the best option for my space. Likewise though the need to cover the vents also seems like it might be a good idea - if I don't need to extract fumes but need to contain dust (such as when drying film), using an air condition / heater is probably the answer where I wouldn't want a lot of airflow.

It's a lot to think about haha.

[Doremus Scudder]

If it were me, I'd just go about sealing the floor and the doorway(s) well enough that your exhaust fan pulls air in through the filters. I have cheap linoleum flooring and vinyl wallbase in my darkroom to seal the floor; the one door is light-tight (and pretty air-tight) with weatherstripping, a vinyl threshold and a sweep.

Best,

Doremus

[m00dawg]

If it were me, I'd just go about sealing the floor and the doorway(s) well enough that your exhaust fan pulls air in through the filters. I have cheap linoleum flooring and vinyl wallbase in my darkroom to seal the floor; the one door is light-tight (and pretty air-tight) with weatherstripping, a vinyl threshold and a sweep.

Best,

Doremus

I thought about that yep! TuffShed recommends not sealing the floor though due to moisture build-up, I assume, on the bottom side. It'd probably take a while for that to cause problems though. I have some weather stripping on the door already though mostly to help with light leaks.

[Doremus Scudder]

I thought about that yep! TuffShed recommends not sealing the floor though due to moisture build-up, I assume, on the bottom side. It'd probably take a while for that to cause problems though. I have some weather stripping on the door already though mostly to help with light leaks.

Your Tuff Shed floor likely doesn't leak a lot of air; it's just porous enough to breathe and not be a moisture barrier. You could just fill cracks/spaces in the floor without finishing it and get it air-tight enough for your fan not to pull air from the floor, but through the filtered louvers.

For outdoor applications, I think the dryer-vent idea is really good; should be adequately weather-proof. A screen over the intake to keep buglies out might be good.

Best,

Doremus

[Tin Can]

I used one of these at my last location, by removing a glass brick.

Worked great and sealed well, no birds, very little cold air as I also installed a DIY cap inside and removed it when actually using DR.

https://www.amazon.com/Broan-641-Rou...ag=googhydr-20