Instructables
In areas with low humidity, regular air conditioners don't work very well. A simpler solution uses water evaporation to cool and humidify air. These are called evaporative coolers or swamp coolers and are used in homes all over the Southwest U.S. Air is pulled by a fan across a wet pad, which lowers the air temperature by 20-30 degrees, and provides much needed humidity as well.

We attend a week-long festival in the remote Nevada desert, where daytime temperatures climb well over 100 degrees F.In this situation, it is necessary to be completely 'off the grid', self contained, and self reliant. In order to remain comfortable, we made portable swamp coolers out of common materials, powered by solar panels, to cool our enclosed living spaces. They have also been used at home in more permanent installations to cool greenhouses. Additionally, they could provide temperature regulation to desert homes where electrical power is not available.
 
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Step 1: Materials

36-44 gallon heavy duty trash can with lid
Evaporative cooler pad x 12 feet x 29 inches
Hardware cloth or chicken wire x 6 feet x 24 inches
Submersible 12 volt bilge pump x 1
1/2 inch irrigation tubing x 10 feet
1/2 inch T-connector for irrigation x 1
Automobile radiator fan or solar fan x 1
16 inch diameter HVAC tubing
Large drain pan
U-bolts x 3
Solar panel and deep cycle battery


Step 2: Examples of materials

Picture of Examples of materials
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With the exception of the fan (and solar panel if you use one), most everything can be found at a Big Box Hardware-type store (Lowes, Home Depot, etc). Much of it can be scrounged for free, as well, if you are patient and resourceful.
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north40nm2 months ago

very kool (see what i did there ;) am thinking to build one for my camper @ the burn this year... really 2 gals/hr? just run for the hotest part of the day i guess. cheers mate, and good job. a thought, if you had the mesh on both sides and made a cylinder inside the barrel, you wouldn't need the outer catchment? As the builder, you think that would work???

johnny3h3 years ago
@ Twoyellowdogs.  The output of any swamp cooler depends on two things:

1.  The Relative Humidity of the air it has to cool by evaporation, and
2.  The size of the unit [amount of SURFACE AREA through which the air is drawn].

I notice that your trash can hole pattern  leaves LOTS of un-cutout area.  I would guess you have about a 40 to 45% open area. 

Without changing ANYTHING else, IF you would either drill the holes larger so they ALMOST TOUCHED each other, OR drilled a lot more smaller holes in between, you would INCREASE the surface area of the matting for airflow, and thus INCREASE volume of cooled air created.

Ideally, like the commercial swamp coolers mounted on the Tucson rooftops, the wet mat area would be massive, with ONLY a thin metal framing to support the matting, hoses, and fan.

You could accomplish this by either drilling more holes, OR replacing the trash can with two layers of "hardware cloth" with the matting sandwiched between, and then just the bottom of the trash can at the bottom as a reservoir.  The double layer of say 1/2 inch hardware cloth would be more than strong enough to support the system, AND provide almost 100% exposure of the wetted padding to the air flow.

NO offense is intended as you have created a great cooler AND a great 'ible.
kanemaui johnny3h3 months ago

Aloha!!! EXCELLENT points, johnny3h! The original idea is basically pure genius, but with some of the modifications you mention, this system would be pretty stellar. But, seeing as how tooyellowdogs built this to be used in an area where the dust is almost as fine as baby powder (so I've heard from 'Burners'), not to mention, 'windy', the unprotected moisture matting may be subject to clogging from the random/fugitive dust flying around and collecting turning (possibly) into 'mud'. Just a thought ~ ~ ~ I plan on building one of these for a greenhouse/grow space in a high desert location where humidity is almost totally lacking ~ ~ ~ Aloha ~ ~ ~

anitagreen5 months ago

You have made a great swamp cooler, really nice design! But, I think it's not worth it spending so much money and time on this product as it would be not effective in extreme humid conditions. You should have purchased portable air conditioning instead which is great for humid for humid climates. Visit the following website for more useful information: http://www.amtekair.com/

tooyellowdogs (author) 1 year ago
You probably need about 3-5 gallons to prime the system and get all the pads wet then about 3 gallons per day. We used cooler melt water (ours and as many neighbors as we could get water from) to supplement the amount of water we brought onto the playa.
jantonio81 year ago
I'm building one of these for the upcoming burn. How many gallows of water does it use per day/hour. As you know, it's not like we can go to the faucet if we didn't bring enough water.
bryan31411 year ago
would it help significantly to rig a tarp to provide shade over the cooler and the duct work?
Ericson5781 year ago
How did the dust on the playa affect how the cooler ran?
tooyellowdogs (author)  Ericson5781 year ago
I did not notice any problem with the dust. Much of it is washed off with the water drip. There will be mud in the bottom pan, but not enough to bother the pump. I replaced the blue pads every 2 years.
where did you get the giant ducting tube?
dropkick2 years ago
If your worried about humidity in your house you can sew some cloth sacks then fill them with kitty litter (the inexpensive clay type) and hang them up.
When the litter needs to be rejuvenated you put it in a pan in your oven for about an hour at 300F to 400F, let it cool and then put it back in the bags.
We've used this method for years.

If you want pretty you get a cotton print cloth for your sacks. If you want utilitarian you use canvas. If you're a bachelor you use tube socks.
Zombie_BBQ3 years ago
this is nice ,but only works in near zero humidity.i live in Tucson,Arizona swamp coolers are used every where .but if it gets above 25% humidity it wont blow cool air anymore.
@ Zombie_BBQ.  Since 1954, we have lived in SE Texas [on the Louisiana border, AND ONLY about 8 or 9 miles in from the Gulf of Mexico. We DO HAVE HIGH HUMIDITY!!!!!

Evaprative cooling WILL work at 99% Relative Humidity, BUT... the key issue is that as the humidity goes UP the effeciency goes DOWN.

Also, another issue inside the Tucson homes is that the evaporated water vapor is DEPOSITED INSIDE the home, and thus contains the heat and that "builds up."

When you say the humidity is above 25% I suspect you are talking about the ambient OUTSIDE humidity. When that 25% air is drawn into the cooler, and evaporation and cooling DOES STILL occur, the humidity INSIDE the home MAY reach near 100%, and then there is no cooling.

I suspect that IF you open [just an inch or two] ALL WINDOWS in the house, then even at 25% outside humidity, the swamp cooler will be more effective.  By "venting" as much air as is taken in, you will hold the interior humidity down nearer the 25% mark and enhance the sensed cooling.


But even at high humidity [say 90% at 100 degrees F] a swamp cooler did work for years but the REALLY BIG PROBLEM was the enhanced high humidity INSIDE the houses cause EVERYTHING TO GROW A COAT OF MOLD/MILDEW.

When I was a kid over 60 years ago the swamp cooler was the ONLY air conditioning we had here.  Agreed that it wasn't perfect, but it was better than nothing I assure you.

Believe me as I speak from experience, evaporative cooling WILL WORK at high humidities.
How many gallons per hour does the bilge pump need to move? I imagine that a smaller pump would be plenty sufficient.
The goal is to keep ALL of the padding constantly wet.  That does not require much circulation it the water outlets around the top of the pad are adequate in number, spacing, and size.

In the whole-house window unit swamp coolers I recall as a kid 60 years ago, the pump was nothing more than a CHEAP SUMP PUMP that people used to keep their basement sumps pumped out. They operated on 110-120 AC volts so they simply were attached to the wiring for the blower fan.

A small boat bilge pump should be adequate, but you would need a 12 volt DC power supply of the proper current [Amps] rating.
tooyellowdogs (author)  variablechange3 years ago
The issue is more having enough pump power to furnish enough head pressure to get the water up to the top. You can control the output by limiting the number and size of the output holes. You are right, you only need a trickle of water thru the pad. But it takes a sufficient pump to get it up there.
tiggerbob4 years ago
To use the evaporative cooler in more humid areas, one would need to dry out the incoming air. One way is to build a frame and attach heavy duty screen on both sides and fill the frame with water softener salt and set the frame in front of the cooler intake. when the salt gets too moist, set the frame out in the bright sun. It would be good to build two frames. One could be drying while the other is in use.
That's a great idea! I was thinking about doing something similar, but on the output side, to ensure that I don't humidify my home to the point that I invite rust and mildew. I was wondering what I should use for a low-cost reusable desiccant.  This should fit the bill nicely!

If I ever get around to doing this (I'm thinking about one for the garage), I'll post some pics and let you know how it goes.
mwetzler3 years ago
where did you get your fan?
tooyellowdogs (author)  mwetzler3 years ago
it has been so long since I got the fan I can't remember exactly. Internet search solar supply or solar fan. That's how I found one. Sorry I can't remember the site. You may also want to see e-playa, a Burning Man chat site, under the subject: Cooling Your Tent or Van. for further detailed evolution of this idea, including sourcing updated materials. More great ideas there.
mwetzler3 years ago
nice shower; i want to camp with you!
joshcali3 years ago
Hey! about how many gallons a day does this use at burning man. Also, do you have/know inexpensive sources for cheap solar panels?

I'm really interested in this. love BM, but hate the heat. Would love a good RV alternative!
richardcole3 years ago
im not understand this whole project. from where it is look like cooler.... ???? tell me.
tooyellowdogs (author)  richardcole3 years ago
If I understand your question...the theory is to pull dry, hot air through a wet material. this causes evaporation of water which cools the air 20-30 degrees F. When this air blows on you via a fan, you are cooler. the lower the humidity of the outside air (hotter and dryer), the better it works. there are big,metal ones installed on top of homes and businesses in the Western US to cool the air inside. This project is made from recycled and easily obtainable materials.
Galileogst4 years ago
This is so awesome! My family and I hope to attend Burning Man next year, so I'm always on the lookout for ways to keep us comfortable in the extreme environment. I have not read all of the comments, so please forgive me if someone has already asked, but would you consider doing an instructable on how all of your burning man "home" items are made and used. Like the truck tent, the shower, your kitchen, etc. It's all so great looking and you did a wonderful job! Thanks for taking the time and energy to share. :)
tooyellowdogs (author)  Galileogst4 years ago
i'd be glad to help you. The truck tent is a Flip-Pac, they have a web site. Most other Burning Man related questions can be answered by searching e-playa, accessed from the Burning Man website. I have addressed our grey water disposal method (refined over 5 years) there, you can search for posts by author, look for Yellowdog. PM me at jkprager@hotmail.com if you need.
Thanks for the information! I'll check it out!
kenbob4 years ago
Excellent instructable. Now i just need a vacation someplace hot and dry to motivate me.
This is the coolest instuctable I've run across all year, thank you for posting.
Ranie-K4 years ago
Would this work for a house?
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KittyF Ranie-K4 years ago
if you're asking if a swamp cooler works for a house, then yes, my brother lived in NM and used a swamp cooler to cool his house. His used a fan. If you want to be off grid with your swamp cooler you need a way to blow the cooled air throughout the structure such as this person used with solar panels.
Ranie-K KittyF4 years ago
Well, my question is if the air getting cooler (and will therefore sink) would be enough to make the air circulate: Inside air getting warmer, entering upper vent, entering swamp cooler, sink and finally enter the house again.
KittyF Ranie-K4 years ago
I'd think that question would depend on how large your space is, and how broken up (with walls or furniture) it is. FWIW, Kitty
Ranie-K Ranie-K4 years ago
Air is led from a vent near the roof in a insulated pipe into the swamp cooler, where the pipe (but not the house air) is in contact with the moist media. Evaporation make the air cooler and presses it down, trough insulated pipe and into an vent near the floor. Water is release into swamp cooler from mains or rain barrel as shown.
sputnikII4 years ago
Forgot to mention a couple of things. Place hardware cloth (like chicken wire, smaller holes) over hole pad covers. Keeps out critters & gives support to pad. I used window screen but it's a bit restrictive and calcium deposits clog it a bit. Secondly, on the HOTTEST Mojave Desert days, my cooler uses 5-6 gallons of water. I know very well, because the 1st year I used it I filled it manually from gallon bottles ;) It runs 24 hrs. a day, you would too if you lived here. The pad on this is about 22" X 14". Just about right I think. Determined the size by looking at my buddies 1300 sq. ft. home that has the best swamp cooler I've ever seen. In here it's more like 130 sq. ft. Your water mileage may vary. To lighten the load on my $250 Fantastic Fan I bought an $18 box fan from Walmart and now use it as primary, kicking on the other when it really gets hot. Box fan is mounted outside, hung from roof, blowing outwards with air conditioner foam "sealing" it again a window, that just happened to be exactly the same size as box fan.
sputnikII4 years ago
I made one three years ago for my old Winnebago. There is a window in kitchen pointed right at dinette seating area, perfect. My Winnebago has a Fantastic Fan (brand name), quite excellent CFM, mounted in the roof. So the cooler has NO fan, depends upon the draw from that fan. It works excellent, I am in the Mojave Desert, it was 103 today, highest temp at my seating position was 89, not taking into account wind chill factor from the cool air blowing on me (NICE!). I made the box of plywood, cut large rectangular hole in back for airflow thru pad, square hole in front to same size as my window. Pad is laid over the back hole. On both vertical sides of pad are tiny eyelets, thru these I strung nylon string back and forth to hold the pad in place. Bought a submersible fountain pump and float valve. The float valve maintains about 1 gallon of water in bottom. Float valve is mounted on a steel framing "L" bracket.  Submersible pump sits in bottom, connected to plastic hose, which is run across the top of the pad.  Took a small nail and poked holes every couple of inches in plastic pipe, water seeps thru those, dripping down to constantly wet pad.  Entire inside is coated with Marine Varnish to waterproof. Hung from roof, meshed to window with airconditioner foam, voila! Fan evacuates hottest air at the roof (pushing air OUT), and cool air is drawn thru the pad, striking me. 3 yrs. and going strong. Oh, helps to adequately seal ALL openings everywhere, so that vacuum created by exiting hot air has no other intake source besides the cooler pad. Heck, gotta do that anyway if you don't like living with bugs. Do it, do it now!
spa31rky4 years ago
Terry Catlin The size of the duct work should be basically rated accordingly to the Fan supply. But here is an idea, ............say the fan / radiator is 20" and you want to use a 6" duct. All is needed is a Reducing hub. Basically make a reduction from the 20" down to the 6" that will also increase fan flow. Say the radiator is 20" square.........then you have to start out with a square flange and when reduced to 6" round. Get the picture?
 I wish I could build one here. My friend made one, but only worked for a while due to high humidity. If I do go to North America I will make one.
Jenn Nelson4 years ago
Very nice, and obviously playa-tested!   If I can get my vardo interior temp down from 105 degrees to 75 degrees using an inverter and batteries instead of my gennie, I'll be a happy camper!
CodySteed4 years ago
I used smaller sized materials and some other stuff last time.  I will be making a new rig this year, so I'll do a complementary instructable.

My materials:
 
Simlar set up as the above instructable, however the small pump and fan are solar.
 
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=66093
 
Small Solar Fan http://www.amazon.com/Solar-Powered-Window-Ventilator-Adjustable/dp/B000SZV8I0
 
 
6 inch fan - 225 CFM which is pretty good for a tent and easy to put in a dryer vent exhaust tube.
 
http://www.google.com/products/catalog?q=solar+fan&hl=en&safe=active&cid=481642046482185617&ei=McjMS6rfDZaq2ASuqsTmCQ&sa=image&ved=0CB8Q8gIwBDgA#
 
Medium Sized, really simple to install in duct
 
http://www.northerntool.com/shop/tools/product_200367065_200367065?cm_ven=Aggregates&cm_cat=Google&cm_pla=Alternative%20%2B%20Renewable%20Energy%3ESolar%20Solutions&cm_ite=336620?ci_src=14110944&ci_sku=336620
 
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