Planning my darkroom ventilation system

Jeff Bannow · Mar 4, 2009

So, I am in the process of putting up the walls for my darkroom and I would like to plan for my ventilation needs. The room will be aprox. 18' x 13'.

Here is the layout for the darkroom:

The thicker walls are outside walls. In the bottom left corner is the air intake, which is going to be one of these Dead Link Removed mounted near the ceiling. I was then planning on using pvc pipe with holes in it mounted to the back edge of both sinks, with some kind of suction fan going on. I figure I will need to run duct work to an outside wall where it can vent outside the house.

Anyone care to correct me on this, or provide ideas on how to make it happen? While we are at it, any other words of wisdom before the darkroom is set in stone (or drywall as it may be)?

mjs · Mar 4, 2009

For your sink area, have you considered kitchen stove hoods? They might come with exhaust fans, charcoal filters, etc. If you could find them second hand or surplus, they might be affordable.

Does the outside wall have a window? For periodic cleaning and freshening the air, I would consider at least one which can open to the outside. If it can double as an emergency exit, so much the better.

Mike

Jeff Bannow · Mar 4, 2009

Unfortunately the outside wall has 2 glass block windows, but neither can open at all. There is a window that can open that would be right by the intake vent though.

Marco B · Mar 4, 2009

I have a simple bathroom ventilator connected to a ventilation shaft. It does a pretty reasonable job, even though it's located a meter or so above the trays on the wall. Still manages to supply enough fresh air, in combination with a door with secured, light safe, air inlet.

Vaughn · Mar 4, 2009

I like the system of the PCV pipe behind the sink -- but perhaps with hort. slots cut cut in them instead of holes? Can you cut a vent hole in the outside wall, or perhaps go straight up thru the ceiling?

Another thought I had was a fan and PVC pipe for each sink (but could have a common exhaust pipe)...or the ability to close the vent/pipe behind one of the sinks. That way you could concentrate the pull over the sink with the noxious fumes.

Vaughn

mferrarini · Mar 4, 2009

Pressurize your darkroom. Instead of sucking the air out, blow filtered air into the space from the intake vent and have it exhaust naturally out the exhaust vent. The positive pressure will keep out dust.

Jon King · Mar 4, 2009

I have my wet area (someday a full sink, for now a slop sink and a table) along one wall with 3 rectangular vents spaced along the wet area, about 18 inches(45cm) above the table/sink surface. these vents are ducted to a fan in the attic, then to the outside. My thought was to keep the fumes away from my nose, and it seems to work well.

smieglitz · Mar 4, 2009

Any reason (plumbing, etc.,) why the sinks couldn't be along the outside wall? That would cut down on the amount of ductwork. Have the ventilation drawing from tray level in the sinks with the intake high on the opposite wall. This helps keep you from breathing any fumes. A kitchen fume hood overhead will likely draw the fumes up towards your face and you don't want that.

Personally, I'd keep the NuArc out of the darkroom. While it is running you won't be able to coat or dry alternative process prints or do any silverprinting if the exposure unit is in the same room. Loading the NuArc under incandescent lamps in another room won't present any problems with alt prints. So unless your plan is to expose Lodima or other factory silver print materials I'd put the NuArc elsewhere.

jp80874 · Mar 4, 2009

mferrarini said:
Pressurize your darkroom. Instead of sucking the air out, blow filtered air into the space from the intake vent and have it exhaust naturally out the exhaust vent. The positive pressure will keep out dust.

Filter the air coming in through a high quality furnace filter or you will have lovely little white spots on your prints.

I like Panasonic whisper fans. The only noise I hear is air in the pipes. They have worked well for four years now.

John Powers

Jeff Bannow · Mar 4, 2009

Lots of great suggestions. I need the sinks where they are due to the drain being there. I was thinking of venting outside and using a dryer style vent flap to keep the critters out. I can't vent through the ceiling as that would be into the living room!

The NuArc could go outside the darkroom though, although I've got some Azo I'd like to play with. If I did that, I would need to move the wall a bit. Decisions, decisions ....

John, I will take another look at your setup when I'm down there in a few weeks, if you don't mind. Those Panasonics look pretty nice.

JG Motamedi · Mar 4, 2009

Dead Link Removed

Jeff Bannow · Mar 4, 2009

That link looks very helpful and close to what I was planning. Are those vent hoods available cheaply? (I know, wishful thinking probably ...)

Davesw · Mar 4, 2009

mjs said:
For your sink area, have you considered kitchen stove hoods? They might come with exhaust fans, charcoal filters, etc. If you could find them second hand or surplus, they might be affordable.

Does the outside wall have a window? For periodic cleaning and freshening the air, I would consider at least one which can open to the outside. If it can double as an emergency exit, so much the better.

Mike

I used a 36 inch SS unit from Braun. I had it left over after a kitchen upgrade so it was an easy choice for me as it was surplus, but the truth is it has worked out great,it has built in lighting that I can just reach up and turn on for print inspection. it runs quite and moves plenty of air to keep fumes down.
The thing I missed in my design (I am presently correcting) was air intake, the fan would try to pullair but the light sealed door in the room would not let in makeup air. I plan to add ducting to let n fresh air and a furnace filter to keep down dust.

JG Motamedi · Mar 5, 2009

jbannow said:
That link looks very helpful and close to what I was planning. Are those vent hoods available cheaply? (I know, wishful thinking probably ...)

They are simple to make out of wood with even the most modest of carpentry skills.

Budget a $150 or so for a 500-1000 CFM fan. These can be bought cheaply from indoor garden supply stores with the appropriate adapters.

resummerfield · Mar 5, 2009

I use an exterior kitchen vent fan, ducted to a plenum over my sink. I think this would be very similar to the PVC pipe you suggest.

I would punch a hole through the wall above the film dryer, mount the exhaust fan outside (which would be much quieter), and duct this to your PVC.

Just for reference, my exhaust fan can pull about 600 cfm, and I have it on a rheostat to further cut down noise.

jp80874 · Mar 5, 2009

jbannow said:
John, I will take another look at your setup when I'm down there in a few weeks, if you don't mind. Those Panasonics look pretty nice.

Also take a look at the sink drain, 1 ½ pvc pipe, that runs 36 feet to the sump from the bottom of a waist high sink. The liquids flow like a torrent. You may be able to have your sinks anywhere you want them.

John

mgb74 · Mar 5, 2009

I would be concerned that the pvc pipe might not have enough volume for airflow (it will be relatively low pressure) - unless it's fairly large diameter (6-8 inches). I would consider rectangular aluminum duct (3.25x12 or 14) with 4" round vents cut in every 2 feet over the sink. All "off the shelf" stuff. Then, you could transition to 6" round duct and an inline fan (placed in the darkroom or outside).

Jeff Bannow · Mar 5, 2009

I think I could probably vent out above the film dryer, but would have to check the outside of the house. That would be easier though for sure. We are planning on running 2 20 amp circuits for the darkroom - hopefully that will be enough to power everything. We will also be using a Thomas safelight in the center of the room, and a flourescent light panel for cleanup lighting as well. We will then put clip lights around the room where we might need a little extra.

Keep the ideas coming everyone. This is helping a lot.

L Gebhardt · Mar 5, 2009

Skip the fluorescent lights as they keep glowing for a while after you turn them off. The darkroom is one room where I'll gladly waste a bit of electricity so I don't waste my film or paper.

Jeff Bannow · Mar 5, 2009

L Gebhardt said:
Skip the fluorescent lights as they keep glowing for a while after you turn them off. The darkroom is one room where I'll gladly waste a bit of electricity so I don't waste my film or paper.

Any idea how long it takes to adjust? The light is already there in the room. I was thinking we would just wait 5 minutes or so after turning it off.

That light would only be used for setting up and tearing down the equipment - I'll have other light for print assessment and such.

CBG · Mar 5, 2009

A couple of random thoughts:

Anything but fluorescents. LEDs are low electrical usage if carbon footprint is your concern.

There are PVC landscape drainage pipes made with thin walls that can be purchased in largish sizes without busting the budget so you can get quite a few CFM venting your space. Pressurizing the darkroom is better than sucking air out - you will push dust out - rather than sucking it in. Filter your air source.

jp80874 · Mar 5, 2009

jbannow said:
I was thinking we would just wait 5 minutes or so after turning it off.
.

Having watched and heard the Bickersons set up a tent across the pond from our house, I want to sell tickets to watch & listen to you two patient people wait five minutes every time you turn on that light.

John

jp80874 · Mar 5, 2009

mgb74 said:
I would be concerned that the pvc pipe might not have enough volume for airflow (it will be relatively low pressure) - unless it's fairly large diameter (6-8 inches). I would consider rectangular aluminum duct (3.25x12 or 14) with 4" round vents cut in every 2 feet over the sink. All "off the shelf" stuff. Then, you could transition to 6" round duct and an inline fan (placed in the darkroom or outside).

I have used 4" PVC pipe quite happily the last four years connecting to two Panasonic whisper fans that sit in the rafters. The 4" pvc come down from the rafters and pick up at the side of the trays away from me.

As mentioned earlier if you have "vents cut in every 2 feet over the sink." the fumes are drawn up past your nose. That is what you are trying to avoid. If you have them across the sink from you the fumes are drawn out of the trays away from you and out.

It also helps to have the input air coming from behind you so that the flow goes from behind you, around you, across the trays and out.

John

Jeff Bannow · Mar 5, 2009

jp80874 said:
Having watched and heard the Bickersons set up a tent across the pond from our house, I want to sell tickets to watch & listen to you two patient people wait five minutes every time you turn on that light.

John

It is true - my wife is wrong a lot and doesn't want to admit it.

However, we would only need to turn on the light before printing and when cleaning up. I think we can manage to keep the fists from flying! For print evaluation we will use a separate non-flourescent bulb.

jp80874 · Mar 5, 2009

jbannow said:
It is true - my wife is wrong a lot and doesn't want to admit it.
.

May I read this to her when you guys visit the 21st?

John

Planning my darkroom ventilation system

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