Heading to Burning Man this week and built a DIY swamp cooler for the tent. Staying up late and sleeping in seems like the way to roll and sleeping/sweating in a hot tent is absolutely no fun! Of course this isn't just useful for Burning Man and could be used any time you want to cool down a tent, RV, small room, etc.
In my test in summertime Colorado it cooled the air from 92F to ~68F.
That said.... this is what is know as an evaporative cooler (swamp cooler). It works on the principle that as liquid water converts into a water vapor as it evaporates it cools in temperature. In order for water to evaporate the air needs to be dry with minimal humidity so this won't work well in humid climates. This is NOT an AC unit which uses compression to cool the air. To learn more head here: https://en.wikipedia.org/wiki/Evaporative_cooler
I wrote this Instructable because all of the other designs I could find were either super complicated, didn't provide good instructions, or didn't look like they would work well.
Total build time was about an hour and a half
Credit: My design is based off of this design I found by victorg6546 - https://www.instructables.com/id/Figjams-Swamp-Coo...
Step 1: Gather Your Materials
2" Hole Saw ( https://www.lowes.com/projects/woodworking-and-cra...)
Drill Bit Set
Twinkle Bay Delta AFB1212SHE High CFM Cooling Fan $12.59
This is a 120mm 12V fan that claims an airflow of 151.85 CFM (cubic feet per minute). This turned out to be perfect. It's not super loud but if you spend more on the fan you could probably get a quieter one that also has the same or higher air flow.
Tiger Pumps 120GPH Submersible Water Pump $12.97
I wasn't sure what size pump to get so I decided on this 120GHP (gallons per hour) pump. After building my unit I would suggest 120GPH being your minimum. Ideally I'd go higher if I made another one of these.
LE DC 12V 2A Power Supply Adapter $7.99
Of course you need to power your fan so this power supply worked quite well!
Valterra W01-1600PB 1/2" I.D.
I decided to go with 1/2" tubing which worked well. I got a 10' roll and still have a lot left.
Active Aqua T Connector, 1/2" $8.38
I actually didn't buy this piece since $9 seemed like way to much to spend on a T-Connector but if you don't have easy access to a 3D printer you might have to bite the bullet and just buy one (see the next step for more details).
5 gal. Homer Bucket $2.97
Cheap and easy to find at Home Depot. Amazon sells buckets as well but a lot more $$$.
5 gal. Reusable Bucket Lid $1.68
Make sure you pick up a lid too.
8 ft. Semi-Rigid Dryer Duct $9.99
Cheapest I could find was this 4" diameter dryer duct. It's easy to flex and aim while your in the tent to get the air in just the right spot.
4 in. Storm Collar $2.49
This piece makes it easier to join the ducting to your bucket lid.
Local Hardware Store
Cooler Pad $7.99
This is designed to spread the water out over a large surface area so it can evaporate efficiently. There are different types so feel free to substitute another if it's easier to get. I found some on Amazon but they were quite expensive and the one at my local Home Depot was a massive roll that I didn't need.
6x - M3 x 20mm Machine Screws (length could be different as long as it's more than 18mm)
6x - M3 Nuts (locking with threaded insert preferred but not needed)
Step 2: (Optional Step) Print Your T-Connector
I'm cheap and didn't want to spend $9 on a T-Connector from Amazon so I just made one on my 3D printer. It doesn't create a water tight connection but since we're putting a bunch of holes to make the water drip out anyway it doesn't matter.
Solidworks and STL files attached.
If you don't have a 3D printer just buy a T-Connector like the one I listed in the previous step.
Step 3: The Exhaust Hose
To prepare the exhaust hose I wrapped the end with Duct Tape (a fair amount) until it was thick enough such that the flange tightly pressed over it (see first image). With the flange snugly in place I wrapped the outside tightly with more Duct Tape, taping the flange to the ducting (see second image). Finally to make sure it was secure I put a bead of glue around the inside edge and let it dry (I used E6000 but an epoxy or caulking would work too). This was to make it air tight and strengthen the part (see third image).
Step 4: Prepare the Lid (Part 1)
Next I found something round that was roughly the same size of the fan (see first image). For me this was a roll of tape but a can? jar? coaster? might work as well. I then carefully aligned it with the center of the bucket lid and using a screw driver I traced/scratched the outline into the lid (see second image). Next I took a razor and cut out the circle (see third image). I actually pushed to hard and slightly cracked the lid so be careful. The crack wasn't a problem though (see fourth image).
Now that I had a hole I turned the lid over and aligned the fan with the hole. Using a drill bit just smaller than the holes in the fan (and without moving the fan) I drilled holes in the lid in all four corners (see fifth image).
Using M3x20 screws and nuts I secured the fan to the lid (see sixth & seventh images).
Step 5: Prepare the Lid (Part 2)
Flip the lid over and grab a ruler. Mark a center line in both directions by scratching it into the lid using your screw driver (see first & second images). Now place the ducting/flange assembly on the lid and carefully center it. Using a drill and drill bit that is slightly larger in diameter than the M3x20 screws drill four holes in the positions shown and using your center line marks as the locations (see third & fourth images). It was a little tricky to start the holes since the drill bit kept moving along the flange so I had to aim the drill at an angle into the flange and once the hole was started I could then slowly angle the drill so the hole went in vertically (see bit in image three).
Once all the holes were drilled I used the remaining four M3x20 screws and nuts to secure the flange/duct assembly to the lid (see fifth & sixth images). Be careful NOT to tighten the nuts very much or it will warp the lid and pull it away from the fan. You want it lightly finger tight. You may want to add some glue or locktight to the nut to hold it in place so it doesn't unscrew itself with the fan vibration. For mine I used self locking nuts that have a nylon insert.
Finally take the barrel jack adapter that came with the power supply and attach it to the fan power leads using a small screw driver. Match the red wire to + on the adapter and - to the black wire (see seventh image).
Step 6: Prepare the Hosing
Cut two pieces of your 1/2" hosing. One 13" long (pump to loop) and one 28" long (loop). Connect both ends of the 28" long piece of tubing to the T-Connector that you bought or 3D printed and, with a very small drill bit, drill a hole every inch or so around the loop. I ended up with 28 holes in mine (see first image).
Be very careful you only drill though half the tubing and NOT through both sides!
Next hook the tube from your pump to the T-Connector making sure the holes are facing down (see second image).
Step 7: Prepare the Bucket
First thing you'll want to do is lay the bucket over on it's side and using your 2" hole saw in your drill, drill a series of holes around the perimeter of your bucket aligning the top of the holes with the ridge as I did (see first and second images). I spaced the edges of my holes about 1.5" apart but I didn't measure closely.
This step is super messy! Next take your cooling pad, fold in half (depending on the size you got) and slip it into the bin. Next take the two cords and route them up through the cooling pad as shown (see third image). At this point I'd recommend flipping the bucket over and trying to shake out as much of the loose cooling pad material as you can. You don't want it to clog up your water pump.
Finally take your pump/hose assembly and slip it down into center to the bottom of the bucket (see fourth image).
Now it's time to add some water! Fill your bucket about half full. You can probably add more as long as it doesn't come out the giant holes you drilled in the side.
Plug in your pump and make sure water squirts out the holes (see fifth image). If water comes out the side of your bucket you can tuck the cooling pad in a little bit and that should fix it.
Time to plug in to fan (see sixth image). Try to place the fan plug as far away from the water as you can but this joint is low power DC so it isn't a safety issue if it gets slightly wet.
HOWEVER, the other end that plugs into your AC power cord is NOT safe to get wet so be careful on that side.
Step 8: Let's Test It!
It was actually 92F outside but I hadn't let the thermometer warm up when I took the photo since I had it inside the air conditioned building beforehand, that's why it shows ~88F and not 92F.
I put the thermometer inside the exhaust tube and ran the pump/fan for about 5 minutes before I pulled out the thermometer to check the new temp. As you can see it's now ~68F or so.
If you make one of these I'd love to hear about it! Please post photos and/or add info on any mods you did in the comments!
Have a great summer and if you're at Burning Man come say "hi" at the Camp of the Psychedelic Puppy :)