Introduction: Arobodude's DIY Burning Man Evaporative AC Swamp Cooler

Picture of Arobodude's DIY Burning Man Evaporative AC Swamp Cooler

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

Enjoy!

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

Picture of Gather Your Materials

Tools Needed

Drill
2" Hole Saw ( https://www.lowes.com/projects/woodworking-and-cra...)
Drill Bit Set
Screw Drivers
Razor Blade

Amazon

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.
https://www.amazon.com/gp/product/B071K8WQNM/ref=o...

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.
https://www.amazon.com/gp/product/B01NBKNG4K/ref=o...

LE DC 12V 2A Power Supply Adapter $7.99
Of course you need to power your fan so this power supply worked quite well!
https://www.amazon.com/gp/product/B019Q3U72M/ref=o...

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.
https://www.amazon.com/gp/product/B003VAY4SA/ref=o...

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).
https://www.amazon.com/Active-Aqua-AAT50-Connector...


Home Depot

5 gal. Homer Bucket $2.97
Cheap and easy to find at Home Depot. Amazon sells buckets as well but a lot more $$$.
http://www.homedepot.com/p/The-Home-Depot-5-gal-Ho...

5 gal. Reusable Bucket Lid $1.68
Make sure you pick up a lid too.
http://www.homedepot.com/p/Leaktite-5-gal-Reusable...

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.
http://www.homedepot.com/p/GE-8-ft-Semi-Rigid-Drye...

4 in. Storm Collar $2.49
This piece makes it easier to join the ducting to your bucket lid.
http://www.homedepot.com/p/4-in-Storm-Collar-4ESCH...


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.

https://store.mcguckin.com/inet/storefront/store.p...


Other
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)
Duct Tape
Glue (optional)

Step 2: (Optional Step) Print Your T-Connector

Picture of (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

Picture of 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)

Picture of 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)

Picture of 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

Picture of 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

Picture of 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!

Picture of 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.

Success!

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 :)

Comments

19GoldenA (author)2017-10-17

Did you design the T connector? It looks awesome!

tom.hobart.3994 (author)2017-08-28

The original design is mine. My pump and fan are 12vdc and 2 gallons of water lasts 5 hours. On the dry playa of Burning Man I get a consistent 30 degree drop in temp. I use duracool pad cause it's easier to work with. Put the fan on the lid and trace around the onside of the fan case.....easy. Here's the step by step destructions!!! Search "FIGJAM swamp cooler eplaya". There will be 1000s on the playa as we speak. Created in 2010.

I've seen a hundred variations on swamp coolers since the 1960s (when I started paying attention to them), including homemade ones in a variety of housings. When you say "the original design is mine", I'm curious what innovation in particular sets your original design apart from all its predecessors? Is it the orange bucket? :)

Most of the bucket designs are spinoffs of the one I created in 2010 that is all 12 volt. I've used swamp coolers since the 60s.:)

Bill WW (author)2017-08-28

OK, you make valid points. But I have made hundreds of jigs and gadgets, the prototype is usually not satisfactory. But after experimentation and modification, they turn out well.

I would be surprised if this cooler design actually has anywhere near 10,000 BTU/hr capacity. A typical commercial window mount A/C unit is around 8000 - 12,000 BTU. But hey, this Instructable is clever. We just should not count on a shop built device made out of a 5 gallon bucket to work miracles.

MarkI36 (author)2017-08-27

Where do you get the gallons of water needed? The system will hold 2 gallons to start. This system will burn through more than a gallon per hour to cool an insulated 10x10 room since it needs to remove 8000 to 10,000 BTU's per hour. A gallon of water can absorb about 7000 BTUs. An uninsulated tent will require much more than 10,000 BTUs per hour removed. This system may work to cool your face but the 68 degree air will mix with the tent air and not do much for the rest of the tent.

Bill WW (author)MarkI362017-08-27

Be nice, Markl. Arbodude has shared a good project.

You are correct that the latent heat of vaporization is about 7000 BTU/gallon. But we do not know the air flow rate of 68 degree air. If his swamp cooler evaporates two gallons per hour (a lot of water) that is 14000 BTU/hr. He needs to source a lot of water, but that is part of the the game. Experiment and learn.

MarkI36 (author)Bill WW2017-08-27

What is Not Nice about my comment ? It is an appropriate question. If he takes his bucket to Burning Man, he will find he needs to source buckets of water.
Glad to see he did not try to push the ice bucket cooler as many do. The evap cooler puts out far more cooling effect, if you can find enough water.
Regardless of the flow rate of 68 degree air, the issue is simply the total BTU's needed to cool a 10x10 room. Those numbers are readily available with window AC charts for 2x4 stud insulated walls with double pane windows, about 5-6000 btu's per hour. Add higher temps like Nevada desert and you quickly exceed 10,000 or much more. I'd hate to see a bunch of systems made then sitting dry as people bake and cuss out Arbodude. Water is not a common commodity at burning man. It cost 50 cents to $1.50 per gallon, if it is available without driving to town.
As you say, if sourcing water is part of the game, people should be made aware of the need.

Bill WW (author)2017-08-27

Excellent project Arbodude, thanks for sharing. Let us know how it worked for you.

DouglasF6 (author)2017-08-27

This would work great for camping in Southern California, New Mexico, Arizona, Nevada and southern part of Texas. Further north may start having to much humidity. Burning man would be a great place for this. With a king cab pickup you could put in the back seat and let it run when you were in a store for a long time and it would keep the cab cool. Just a thought. You could maybe go for a much larger barrel and lid for larger water capacity and still get good results. I would think if you cranked it up in a closed tent and put up some sort of a shade for the sunny side of the tent, or put the tent behind a tall vehicle it would work even better. Fighting old Mr Sun beating on the side of the tent is a tough one. Maybe two tent Poles with a banner stretched between them would be the ticket and easy to carry. I lived in southern New Mexico growing up and this type of cooler graced our roof and worked GREAT ! Good work. I would build one myself if I didn't live in Tampa now !!!

kbear99 (author)2017-08-27

Cool. Just wondering how practical it would be to use a gravity feed system instead of a pump. This would reduce the power requirement by quite a bit. If you want to keep things compact, maybe you could use a wide diameter bucket on the bottom -- wide enough to fit a smaller water bucket and tube on top, side by side. Maybe cut the bottom bucket short if the whole thing is too top heavy.

Regarding the fan, I would tend to get a larger one to reduce noise, like 140mm. 200mm might also be possible. Slightly too big for that storm collar but I imagine you could still make it work.

shahrokhani (author)2017-08-27

https://www.instructables.com/id/A-DESK-TOP-EVAPORATIVE-COOLER/

tacman7 (author)2017-08-27

Seems like I would put the holes lower so they would have farther to travel through the excelsior. Is there a wire grid shelf to hold the excelsior up out of the water?

Nice project, I want to build one this Winter for next summer in the shop.

Thanks

DIY Hacks and How Tos (author)2017-08-20

Cool design. Is it hard to find a power source at places like Burning Man?

Depends. A lot of camps will have generators. If you don't need much power and have a long extension cord some camps will let you tap into theirs.

This unit takes about 2 Amps at 12 Volts (24 Watts). A car battery has roughly 48 Amp Hours of power. If you hooked it up to your car battery with a DC to AC converter for the pump you would probably get about 20 hours of continuous run time (though you would probably have to get your car jump started afterwards). A trucks battery, especially diesel, will likely have much higher capacity.

A solar setup is another option and you shouldn't have any issues running this for many hours off a charge.

LSD3 (author)arobodude2017-08-27

From a fellow burner. Haven't been in a while moved across the country. Hope this year kicks ass. Any way I am into solar R&D. A standard 9"x18" PV panel will run this thing all day long. First use a 12 vdc muffin fan and 12 volt pump. But whether you go AC or DC if you are a burner then you probably camp fish or other similar stuff. Invest in 350 watt inverter I keep one in my truck and the fishing rig. It'll run a standard power tool, phone chargers etc. Get a deep cycle marine battery, they're not much more and are a better battery. I put nothing else in my vehicles. Exide makes a good one. At Burning Man, except for white outs, that will run this rig all afternoon while you sleep and you're ready to join the celebration at night. Have a great time.

WouldYaLookAtThat (author)2017-08-27

This is a great project and I'll be doing it!

I was thinking about the issue of finding a circular template the size of the fan and one way you could do it is to tie a string around a marker, pen or whatever you're going to use to mark the lid. Then put a screw in the center of the lid and tie the string around it so the strings length to the tip of the marking device is exactly half of the diameter of the fan. You'll be able to draw a near perfect circle just the right size.

Also, I happen to have a deep cycle marine battery for my trolling motor and I think that would last almost a week without having to worry about getting jump started. Just another thought.

Again, great job!

Nokota (author)2017-08-27

I've made a similar device before that used ice: the evaporation thing doesn't work in my environment because we have obnoxious humidity in addition to low air pressure problems.

While the ice worked better than evaporation would, the thing still grew a ton of mold very quickly due to the internal moisture. I am curious if this might have a similar long-term issue.

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