View Full Version : Darkroom cooling/air conditioning options
I recently updated a 9x14 foot outbuilding on our property to function as a darkroom and while there are a number of benefits to being completely separate from the main house (beer cave of solitude!), not having a heating/cooling system to tie into is a bit of problem. It will soon be 100+ degrees here in Tucson and I need to figure out how I'm going to cool this building. As I see it I can either use a traditional window air conditioner (the building does have two windows) or I can get a stand-alone portable unit that vents to the outside via a hose. Obviously my two biggest concerns are keeping the room light-tight and well ventilated. Does anyone know if a window ac unit (the unit itself) lets light in? It seems to me that a stand alone unit with a vent hose will be the easiest to install and keep light-tight. Has anyone used one of these units in their darkroom space?
There's also the issue of ventilation, currently I draw in clean air from the ceiling and vent out (via a fan) above the darkroom sink. As I don't want the AC unit to draw in fumes across the space I'm working in, I'm thinking it would be easier to have a portable stand-alone unit that I can freely position in the darkroom to avoid this circumstance.
If anyone has experience heating/cooling an outbuilding/darkroom I'd be interested in hearing your solutions.
Gary Beasley
13-Apr-2018, 12:43
The few window units Ive mounted in darkrooms were mostly light tight, I wouldnt have the film loading table right in front of it. The biggest headache of course is fitting light tight fixtures around the box, and some units allow a little light to trickle past the innards. In that case you may need to create baffles for it as well. I like your idea of the standalone with hoses. One thing to consider is matching the capacity to the enclosure, too big a unit and it doesnt run long enough to dry the air and you can have humidity problems and rusting equipment. You do have the building well insulated?
Jac@stafford.net
13-Apr-2018, 12:53
You might Google stand alone OR portable air conditioner.
They only work for small darkrooms!
Thanks Gary. Yes the building is completely drywalled and insulated, although based on the insulation I saw when installing the wiring I wouldn't say it's "well" insulated. I'm not too terribly concerned about humidity (the current humidity level here is 4%) but you make a good point about matching the capacity of the unit to the size of the room. Humidity could be problem later this summer during the monsoons (typically mid July through September).
Christopher Barrett
13-Apr-2018, 14:55
I'm in the middle of building a new darkroom and plan to use a mini split ac to cool it. They take up less space than portables and should be easier to make light tight than a window unit.
Google that... (https://www.google.com/search?q=minisplit+ac&rlz=1C5CHFA_enUS766US766&oq=minisplit+ac&aqs=chrome..69i57j0l5.3729j0j7&sourceid=chrome&ie=UTF-8)
William Whitaker
13-Apr-2018, 15:19
Swamp cooler cheaper than A/C? and since you're in Tucson anyway....
Jac@stafford.net
13-Apr-2018, 15:29
Swamp cooler cheaper than A/C? and since you're in Tucson anyway....
And the added humidity might help suppress dust and static!
Swamp cooler cheaper than A/C? and since you're in Tucson anyway....
Yeah I thought about using a swamp cooler but they lose their effectiveness when the humidity picks up during the monsoons. They are cheap and would be a good solution for spring/early summer.
And the added humidity might help suppress dust and static!
Yes! Plus the added humidity is actually a bonus for most of the alt process stuff I do.
I'm in the middle of building a new darkroom and plan to use a mini split ac to cool it. They take up less space than portables and should be easier to make light tight than a window unit.
Google that... (https://www.google.com/search?q=minisplit+ac&rlz=1C5CHFA_enUS766US766&oq=minisplit+ac&aqs=chrome..69i57j0l5.3729j0j7&sourceid=chrome&ie=UTF-8)
This actually seems like a pretty good option, more expensive but also more efficient and you get both heating and cooling.
Drew Wiley
13-Apr-2018, 17:05
Hmmm ... or you could simply move to the California coast where the air conditioning is natural. Very low heating bills, and no AC expense. If you live long
enough you could amortize the cost of buying a house around here. Certain trees live that long.
Two years ago I installed window AC in a small upstairs darkroom. The unit was a regular $150 5000BTu device which like most AC units these days has the internal air duct made from molded polystyrene. With sunlight outside this lit up like a floodlamp and was unusable. Being a practical sort of guy I bought a can of black interior latex paint and opened up the AC. Using a small assortment of small brushes I was able to black out the air duct on the inside using the black paint. This wasn't enough, in full sun there were still leaks. In the end I added an exterior top cover plate made from sheet metal and spaced about an inch above the AC case, this kept full sun off the fan housing, the result was a big improvement. This took a few hours to complete, however the end result was worth it, cool darkroom.
I would strongly advise against the stand alone portable ac units. They take up precious floor space but are also noisy as hell. A window unit has most of the business hanging outside so should be quieter and should be light tight enough as long as you seal around the unit where it meets the window.
MrFujicaman
13-Apr-2018, 18:58
Home Depot sells a AC/Heating window unit for about $429. The problem with a split unit is they don't allow outside air in. Pretty much any window unit I've seen lets in light. I have the same problem with my darkroom and I have a baffle in place, but some light still gets in. I have to get in there and rethink the light baffle for the AC unit,
williaty
13-Apr-2018, 21:13
I'm going to throw my hat into the ring for a mini-split. You really should get one with Variable Refrigerant Flow (VRF). Mitsubishi is the class leader with it's Mr. Slim product lines. The nice thing is that you'll get very efficient AC, good dehumidification during monsoon season, no light leaks and, if you ever accidentally have a winter, you'll get heating out of it too.
With a window type AC, air flow is an issue, because it is located in the window, and that may not be how you want the air flow to be.
You may be able to cobble together a DIY duct system to route the cool air to where you want the air source to come out.
Then make an exhaust over/behind the chemical trays.
brucetaylor
14-Apr-2018, 07:50
If you are willing to pay the extra cost I think the split unit is a great way to go. We installed one out at work recently, they take up almost no space inside and are very efficient. I have one of the portable units in my darkroom. The newer ones aren’t that noisy but they do take up precious floor space. The tubing is not light right either, I had to build a light baffle where it vents to the outside. A window unit would be my second choice after a split unit for the space savings.
Hmmm ... or you could simply move to the California coast where the air conditioning is natural. Very low heating bills, and no AC expense. If you live long
enough you could amortize the cost of buying a house around here. Certain trees live that long.
You’re actually the second person this week that suggested I move to California. Maybe the universe is trying to tell me something.
I appreciate everyone’s input on this. I’m leaning towards the mini split for its efficiency, heating and cooling abilities, and ease of light proofing. After some research it looks like I can install it myself without too much difficulty.
sepiareverb
14-Apr-2018, 11:48
My small window unit does leak light, if I needed it in my darkroom I would open up the front end and spray the interior of the vents with flat black spray paint.
williaty
14-Apr-2018, 13:14
I appreciate everyone’s input on this. I’m leaning towards the mini split for its efficiency, heating and cooling abilities, and ease of light proofing. After some research it looks like I can install it myself without too much difficulty.
You can do 90% of the work yourself, but I strongly encourage you get a professional to do the plumbing. The reason is that if you get anything into the system that shouldn't be there, it'll quickly destroy the whole thing. Too much humidity, too much ambient air, etc, and the whole thing is ruined. A professional will have the skills and tools to connect it without contamination or to pump it down and recharge it if they suspect something may have leaked. Definitely mount the compressor, mount the head, run the lines, etc yourself. Just leave the system sealed and let a pro make the connections.
Drew Wiley
3-Dec-2020, 10:35
An isolated outdoor conditioner pump connected by tubes to an indoor unit will be light proof, a window unit won't.
I used a portable unit for several years in Richmond VA. We have high humidity most of the year. The portable worked ok. But it only lasted 3 or 4 years, I think. When I redo my home darkroom (I am using membership community darkroom now). I will install a window type unit into the wall or go with a mini-split.
I have been considering a dedicated outbuilding instead of the outdoor entrance utility room I have set up now for replacement. 9x14 seems like a good size as does 12x12 or 8x16. Insulation is key. My ventilation is directly above the sink and below my head. Air comes in via a baffled and filtered 14x12 vent installed low in the wall. And the darkroom has a door that separates it from the space for the washer and water heater. My problem is that I can only get 5x7 feet. And that is a tight fit for anything more than 11x14 since my sink is only 5 feet .
Jim Noel
3-Dec-2020, 11:57
You can do 90% of the work yourself, but I strongly encourage you get a professional to do the plumbing. The reason is that if you get anything into the system that shouldn't be there, it'll quickly destroy the whole thing. Too much humidity, too much ambient air, etc, and the whole thing is ruined. A professional will have the skills and tools to connect it without contamination or to pump it down and recharge it if they suspect something may have leaked. Definitely mount the compressor, mount the head, run the lines, etc yourself. Just leave the system sealed and let a pro make the connections.
The systems are almost foolproof to install. Little or no danger of escaping gas. Only tool not found in most toolboxes is a 3'" hole saw. Be sure to get a tungsten carbide tipped one.
brucetaylor
6-Dec-2020, 16:59
I currently use a portable unit. It works pretty well until ambient gets over 95F, then it’s not very effective. It is reasonably quiet. It takes up precious floor space. I have one of the split units at work, it works great and requires no ducting. I’m going to get a split unit installed before the weather heats up next year. Whatever you do, don’t get a unit that is marginally adequate for your space, it will disappoint you.
Agree!
DIY
The systems are almost foolproof to install. Little or no danger of escaping gas. Only tool not found in most toolboxes is a 3'" hole saw. Be sure to get a tungsten carbide tipped one.
brass.duet
8-Dec-2020, 17:39
I built my 7'x10' darkroom in 2018 and acquired a Honeywell AC portable unit that is rated at 500 ft^2 and 229 CFM. Before I got this cooler, I had designed my ventilation to maintain a positive pressure in the room to avoid particulate ingress. At the max filtered air supply rate, with the AC on low, the balance skews to the "I can't keep up!", with the AC drawing more air out of the room than can be supplied (exhaust fan being off). As a compromise, I cool the room when I am not "dark", as needed. Additionally, it also disturbs the air flow pattern for sink exhaust to function correctly. Based on my experience, I think the standalone portables are not optimal for a darkroom.
Julie
neil poulsen
9-Dec-2020, 02:13
This all relates to a project that I'm just beginning. Please bear with me a bit, it's a little long winded.
Decades ago, probably the mid to late 90's, I purchased a "Photo Therm" device at a swap meet, thinking that I could use it for a temperature controlled water bath. It's been in a cabinet ever since. Last week, it occurred to me how I might use this device to control the temperature in my darkroom. (Keep it warm enough, without going overboard.) So I pulled it out, and turns out, that is likely it's original purpose. (I think?)
It's shown in the center of the photo. Just to the right of the device is a shiny metal thermocouple that detects temperature, and on the right side of the box itself, you can just barely see evidence of an AC (alternating current) receptacle . Look closely, and you'll see from the printing that it's wired for 500 watts. To test this unit, I plugged a lamp into to the receptacle, and heating the thermocouple above a threshold turned off the lamp. Letting the thermocouple cool below the threshold turned the lamp back on again. As you might assume, the dial in the center adjusts the level of this temperature threshold.
I heat my small darkroom with a small, ceramic heater. It works really well, except that the built in thermostat does a lousy job properly controlling the temperature at the interior of the room. My thought was to plug my heater into the Photo Therm's 500 watt receptacle, and place the thermocouple near my developer (?), but also towards the center of the darkroom. This will all work well, except that a 500 watt receptacle won't power my 1600 watt heater. So I will splice in a 2500 watt relay between the heater and the Photo Therm receptacle to provide the necessary wattage to the heater. (The relay is just to the left of the Photo Therm in the photo.)
The relay's function is to kick in the needed wattage to the heater, when it receives power from the Photo Therm. (The wattage needed to trigger the heater through the relay is far less than the 500 watts provided by the Photo Therm.) Working all this out, I was delighted when I noticed that the relay could also be wired in an alternative fashion. That is, it can be wired so that the relay turns on when the temperature increases above the threshold, and it will turn off the relay when the temperature falls below the threshold. (This is just the opposite of how the Photo Therm functions on it's own.) So through the relay, and with this alternative wiring, my Photo Therm unit can be used to cool the room by connecting an air conditioning unit to the relay. In fact, I can wire the relay to connect to both an air conditioning unit and a heater at the same time, so that it would turn on the air conditioning when it gets too warm, and turn on the heater when it gets too cool. While possible, I don't think that it would be practical to do this. Better to have only the heater turned on, or only the air conditioner turned on, but not both at the same time.
I will wire the relay in a project box that will have two receptacles in it and two plugs on two lengths of cords that extend from the box. One of the two plugs will go to the 500 watt Photo Therm receptacle, and the other will plug into an AC wall receptacle in the darkroom. As for the two receptacles installed in the project box, the air conditioner can plug into one of them, and my ceramic heater will plug into the other. (Of course, it matters which is plugged into which.) The Photo Therm will need it's own power source, so it will be plugged into it's own wall receptacle that's nearer to my developer.
One can see how this project of mine relates to the current thread. So, I thought that I would give this "brief" account of how it can all come together. The Photo Therm device is nothing but a portable thermostat; I'm wondering if something like this might be available on the internet?
When I get this all put together, I will post it with detail in the DIY forum on this site.
Neil,
I like hacks but always worry about old electrical devices, especially when daisy chaining high current
It is good the control device is in a metal can and has a grounding plug
Make sure the rest of the parts are also and well away from any water
There must be a better way
CarolClark
8-Jul-2021, 00:36
I also had many headaches with my old cooling system from my house at the beginning of June. I've tried many times to solve this problem with my own hands but with no choice. It was impossible to stay in the house during the day, especially if you live in Houston. Anyway, I've found some good experts from https://www.majorcooling.com/ that solved the problem in a few hours. I was delighted when I see that my cooling system is working and I don't have to be worried. Always is better to call experts to help you than trying solving all on your own.
brass.duet
3-Sep-2021, 17:09
Are your a/c filters clean? Without adequate air circulation around the coils, the heat exchange process cannot happen, Captain. If not that, it's time for a professional assessment.
Sent from my SM-G950U1 using Tapatalk
brucetaylor
4-Sep-2021, 15:20
And some units shut down a/c function when clogged filters are detected. If it is a window or portable unit it probably means it is time to buy a new one.
I did a window mounted AC unit (I built a wall opening for it) in a garage DR. I had to find light tight vents to balance the air. Wall (window) mounted units blow air in to the room but, suck from the outside. I had to provide a vent to balance the pressure. It was soooo long ago....I don't remember where I got them but, they worked and the AC unit was light tight..
(during construction) the city building inspector requested ventilation and I found it.
AndrewMC
31-Jul-2023, 04:27
If you're still facing issues, don't hesitate to get a pro assessment.
Tin Can
31-Jul-2023, 05:09
I converted a small bedroom to DR, I have Central HVAC
I WAS worried about many things
I added a 6 gallon portable humidifier for winter
Under my SS DR sink
I covered the one big window in layers, 2 sheets of plywood and white blackout film to hide DR outside view
It is now my tornado hide
AsynMike
1-Aug-2023, 04:18
Hey, Captain! Good point! Checking and cleaning your A/C filters regularly is crucial for proper air circulation around the coils. It keeps your system running smoothly. If you're still facing issues, it's wise to call in the pros for a thorough assessment. They'll have it ship-shape in no time! By the way, if you need a/c repair in Tampa (https://hot2coldairconditioning.com/air-conditioning-repair-services-tampa/), there are experts who can help you out ��
actually i am letting most foliage cover my windows
and shade my ac
when leaves fall
I trim
My darkroom occupies the back third of my garage. It is full insulated, with a concrete slab floor. No windows. It stays reasonably cool in the summer, but it is chilly in the winter (by Southern California standards). No need for AC, a small oil-filled heater for the winter.
Maris Rusis
1-Aug-2023, 16:59
I get lots of 90+ Fahrenheit days in summer so I equipped my small darkroom with a 2.5kw split system air-conditioner. The "split" involves a minor hole in the wall that is easy to make light-tight. Hinged pieces of black card cover the function lights so the system is film safe.
One important consideration is darkroom fume control. The usual recommended volume of outside air (at 90+ degrees!) pumped into the darkroom to replace air sucked out by a fume extractor will defeat the air-conditioner no matter how hard it runs. The gap between 90F and 68F is just to much. My solution was abandon the fume extractor system entirely and move to odorless chemistry. Costs a little bit more but works well even for the other darkroom user who is an asthmatic.
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