Setting up a color darkroom

Hi all. I'm in the wee early stages of trying to set up a color darkroom. I have a Kreonite Promate processor which I'm going to use but am having a problem figuring out how I'm going to keep my darkroom cooled (I live it Texas and it gets crazy hot here). My basic plan is to have a room which has an enlarger, sink and the processor in it and then to have second and maybe third, smallers room, with additional enlargers in them so I can maximize my darkroom time by printing from multiple negatives at the same time.

So here's the question: can I make this work with window unit air conditioners or will I need to have central ac? I have window units in my house and I know they aren't light tight but I was wondering if anyone had experienced using window units in a darkroom and was able to find a work around? I haven't decided yet on where the darkroom is going to be (converted porch, new metal building in the backyard, some sort of small commercial space I might buy if I can find one, etc) but am trying to get a sense of how my budget is going to hold up.

Any other ideas, advice, etc? I'm looking to do this well and don't have a ton of money to spend but am willing to drop some cash. As it is, I have to go half way across the country to print color and it really puts a hamper on both my productivity and my timeliness.

Thanks for your input!

Jennifer
www.jlfm.net

Jennifer,
The window units work fine even if they aren't stuck in a window. I use one in my darkroom/garage in the summer. I just set it on some crates and turn it on. I circulates the air back through the unit so you have to be carefull not to make it too cold.

Hope it helps.
D.

They make portable air conditioning units. They sit on the floor and connect to the outside via a flexible tube placed in a partially open window. There is a sliding baffle which fills the rest of the window opening. One of these units might solve the light leak problem.

I had two different darkrooms in San Antonio with window units. Both of them, however, were mounted in openings in the wall that were sized to fit and sealed light tight around the unit. Never had a problem with the AC unit leaking light itself.

No larger than most darkrooms are (at least, these 2) a small 110V unit worked just fine.

If you do use central cooling, remember that there has to be an air return, too!

I would use local air conditioning such as a window unit. Depending on the size of the room, I would worry about a "breeze" or dust blowing around so I might deflect the airflow appropriately. In a small basement room with enlarger lamps, processors, timers, etc, some heat build-up can occur. A central unit would make you dependent on the thermostat for the main house. I assume a room specific unit would be much cheaper as well.

Thanks for all your help. I'll investigate these options! It sure is encouraging to hear that something other than central a/c will work - that was going to do me in!

jennifer

Jennifer, I have been doing colour in my current darkroom for the last 18 years. I use an external building in our backyard which was built for the sole purpose of being a darkroom. In the summertime it quite warm here as well.

As my actual darkroom part is rather small 3m x 3m or about 9'6" x 9'6" I thought it would be relatively easy to cool with a small window type airconditioner stuck in the wall. This I did, rather than stick it in the window.

In the window I replaced the pane of glass with a 3 ply sheet of timber that has a hole cut into it. In this hole on the inside I have a light tight ventilation shaft, on the outside I have a secondhand extraction fan with weather louvres to stop water ingress from rain.

I also have a light tight ventilation shaft near the base of the floor which allows fresh air to come into the darkroom.

The airconditioner sits above the paper processor about 1.2 metres away. I always have the ventilation set to fresh air and I have never had light coming in via the unit that I can ever remember, even though it sits on the west wall and gets heaps of afternoon sun.

For what it's worth my little unit keeps my darkroom on hot days (40ºC) around 26ºC measured at 1.5 metres from the floor. My room is extremely well insulated so I would guess that a 15ºC difference is a reasonable enough maximum that these units are capable of doing, bearing in mind that there is a processor running somwhat over 30ºC acting like a little heater, plus your not so cool body as well.

Go ahead, you won't believe the difference, especially when you can hold your hands in front of the air outlet to get rid of sweat, so you can load film onto reels.

Mick.

Jennifer, hopefully I can add a picture of my darkroom some time ago. It shows the airconditioner on the back wall.

I forgot to mention that the processor sits on the brown bench directly under the airconditioner. The grey sink is further back and I rest my elbows on the sink whilst I have cool, fresh air blowing on my face on really hot days. Works really well.

Mick.

Jennifer,

If you are particular about keeping the air fresh in the darkroom (which I recommend), a small wall mounted airconditioner may be struggling to keep the room cool. All wall mounted aircon models that I know of simply recirculate the air rather than bring fresh air in from the outside, and good darkroom design stipulates that the ventilation system should perform at least 5 complete room air changes per hour (preferably more).
To do this, while the air conditioner is running, air should also pass through a light tight vent into the darkroom (say through a special passive light tight vent installed into the door), and then exit towards the back of the sink through some ducting via an exhaust fan in the roof. So not only are you bringing hotter air into the room, you are also exhausting the cooled air out of the room. This will make the air conditioner work over time and it may not be able to keep up. You may need to ask a suitably qualified air conditioning installer to do some calculations for you to see if they have anything to do the job. The maths won't be trivial and they will need to take into account the following variables:-
i) the hottest outside temperature for which the system will still function
ii) the temp of the air entering through the door vent
iii) the flow rate of the air entering through the door vent (and thus leaving via the roof exhaust)

Sorry to be a bearer of bad news for you budget, but in my experience designing adequate darkroom ventilation is not always easy !

regards
Peter

In the case of air exchanges you could get a small heat exchanger unit to precool the incoming air with the exhaust air. I think these units are around 60% efficient, so that would really help reduce your cooling needs.

With color I have found the need for ventilation to be much greater than for black and white. The RA4 chemicals stink, and can't be good for your lungs.

My wall mounted airconditioner has a lever which allows either recirculation or fresh air.

There is a marked difference when I open the unit for fresh air. I always run it in the fresh air mode.

My unit is a Carrier unit made in Japan, high quality and relatively high priced in it's day.

Mick.

Jennifer I have no idea how crazy hot your darkroom gets. Milwaukee is more than 10 miles north of you. Running a Kreonite processor will not make it any cooler. You may be able to the keep the room tempeture below the tempeture of the processor just thru using insulation. This of course does not make it a comfortable place for you tp work in. You might want to consider applying 2 or 4 inch thick Styrofoam on the walls and ceiling and cover with white plastic sheeting. This may not be too terribly expensive. I would imagine that you will end up air conditioning your darkroom. The insulation will pay for itself with lowered electrical costs. If you would cover your enlarger and other items this would allow you to hose down your darkroom assuming it has a drain.

What I think you should do is to install the air conditioner thru a wall. I would build a plenum on the outside of the air conditioner that will either accept HEPA or auto filters and have an exhaust vent within the darkroom that leads back to the plenum..before the filters. This way you would constantly be cleaning the darkroom air. Print spotting might be reduced. Most certainly I would get an air conditioner that has a thermostat. Making sure that the air pressure is higher than the air pressure outside of the room would guarantee that when entering or exiting the darkroom that uncleaned air does not enter it.

Jennifer enjoy your new color capabilities.