Darkroom ventilation (choosing from two systems)

[arigram]

There has been talk about ventilation in the darkroom before.
What I need you to help with, is to choose between two different set ups that are offered by the same company.
Those two models are sold here and I am not willing to look for something else really, especially since its very hard to find most recomendations here in Crete, or even Greece. Also because of the bulk and weight I rather not order from abroad.

The two offers are made by an italian company, Aspira.
My choices are:

* a direct wall mounted air exhaust
- large size of 34x34cm sqaure
- needs a new hole on the darkroom wall around 26cm square
- gives me about 20-25 changes of air in an hour (680 m3/h)
- makes noise of about 49dB from within 1,5m
- will be mounted on the wall at the right of the sink, just where it ends
- it has grilles and opening and closing flaps
- comes with seperate speed control unit
- it doesn't really stick out much
- its the more expensive

* an in-line centrifugal fan
- can be attached to the same pipe I had of a dead exaust unit
- it will need a bit of pipe more to sit properly and protect the fan opening
- it will stick out (about 20cm diameter)
- it will give me about ten changes of air in an hour (235 m3/h)
- it doesn't have a speed control unit
- makes noise of about 62dB
- I can find larger and stronger models but they can become really large
- its cheaper

My darkroom for those who haven't seen it in the darkroom photo thread its about 3x3x2m.
Air will come in from the opposite end of the room via an air conditioning unit.
My darkroom is mostly in the open, apart from the wall that the sink rests against which is the wall of another similar room. All the other three walls are outside walls.

Please look at the included photo.
a) is where the direct fan will sit
b) is about where the in-line fan with a pipe will sit
c) is where the old unit was

What do you suggest?

[Robert Hall]

One thing to note is where the fresh air supply comes from. If it is the door, you will not get much of a help from a fan.

You need to have the fresh air come from one side near the bottom, and exit the other side, near the top.

Otherwise, it looks like any of what you have there will do.

Good Luck.

[arigram]

One thing to note is where the fresh air supply comes from. If it is the door, you will not get much of a help from a fan.

Thank you Robert.
I've noted that fresh air comes from an airconditioner at the exact opposite side of the darkroom, so its pushed in, filtered and its cool.

How many changes of air I need per hour?

[resummerfield]

Get the one with the most airflow (680 m3/h). Depending on how you arrange the make-up air, the air changes per hour will be less than advertised. Sometimes much less. And like others have said, locate the make-up air for cross ventilation. And, the high flow model is even quieter.

[Robert Hall]

Yes, Eric has a good point, and quiet is very nice. I run 2 600cfm fans, one in each room, I have the doors ventilated with light baffles. I have them set on timers that go on 4 times a day and I turn them on when needed as well during toning or some such.

[arigram]

I ended up buying the first one, the big, square type. Tomorrow the worker will come by to open the hole and I will fit it these days. The only concern I have is that it might not be light-tight so I might have to improvise something. I thought of a squared plastic garbage can that I can fit on the outside wall and make a hole in the bottom so the light doesn't enter.

[RJS]

If you set up so air is blown in you will slightly pressuize your room which is a good thing. Helps keep dust out. I did it this way with a squirrel cage blower and an exhaust vent in the door. I could hear things 'creak' a little when I turned on the blower so indeed, it did build slight pressure!

[blansky]

As I preach every time I see a darkroom ventilation thread, I cover my trays that emit fumes with plexiglass.

Fixer and selenium toner cannot be noticed in my darkroom even with the fan off.

So a huge abundance of air replacement is not as necessary.

Nice looking darkroom by the way, Ari.


Michael

[arigram]

Thank you Michael. I have trouble with humidity so its not as sparkling clean at the moment as it used to be but considering this was a post-war laundry room, it transfered well into a darkroom.

[Robert Hall]

sounds like a good idea. Here's to good air!