A long long time ago, when I used to watch the pterodactyls come to the feeder I worked at U of F in the aquaculture department. We had a huge greenhouse structure of sorts for the fish we were messing with. The evaporative cooler they used was awesome. It was a 2" pvc pipe frame that went the whole length of the width of the greenhouse about 4 feet high with air conditioner type filters in it which were held by wires. Guttering at the top had holes in which the water dripped down the filters into a gutter that emptied into a reservior with a pump to get the water to the top and a toilet ball thingy to add water when it got low. There were fans on the other end which sucked the air out. It was astonishing how well that system worked. It never got above 85 degrees no matter how hot it was outside.

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Here's a link on how to make one.

Here is a link that might be useful: Home made swamp cooler

Sure would be nice to have any luck with one here in Humid Dixie wouldn't it cactus!

Bob

I have seen them at three local nurseries here and they don't use them much. All three are basically made the same. Continuous vents across the whole back side that open out. On the inside 1 long pad about 4 ft tall and 2 inches thick. Also the fans were end to end the width of the greenhouse. Maybe 10 fans or so. I don't like the idea of having that much light blocked by the pad. Using one of the premade units (evaporative coolers) seems like it would be very expensive to operate. It looks like an Air conditioner and if it operates like one the cost would be prohibitive to me.
I like the idea of misters or a fogger better. And to me the Aquafogger cools just as well from what I've heard. It is a lot smaller unit, no bigger than a 24inch fan. More pleasing to look out and would use less electricity as opposed to running enough fans to cover one side to the other. The one in the link above is cute and a neat idea. But would only work in a very small greenhouse.
I have also heard they don't work well here. But I think it all depends on your ventilation system. I have enough vents, exhaust fans, and circulating fans that the my humidity is low because of the drying action of the fans.
I think I'll give the greenhouses that have the swamp coolers a call and see what they think about it.

I just talked to Sandy at Hall's Flower Shop in Stone Mountain. She says it works really well. At one end. The closer to the pads and vents the temps are 75* about 2/3 down it stays 100-110* when it's 90 outside. The farther away from the pads the hotter it is. Thier greenhouse is about 30x60 with 60 being the width wise. And they have 8 very large exhaust fans She said she would recommend them. But I only used misters last year and I never had temps much over 92 when it was 90 outside. and when the misters came on it cooled it another 4-5*.
My greenhouse is 32x37.
I would suggest trying the misters first. (You can always use them later for plant watering.) See how much that cools before investing a lot of money into makeing a swamp
cooler or investing in an evaporative unit.
An Aquafogger with an oscillating arm and connection would cost me a little over $1000.00. I will try it first before considering a swamp cooler. Even if I built a swamp cooler my self I would have to invest around $400 for a large enough pump and the pads.
I am also concerned about algae and fungus in the pads. In the winter they would need to be taken out and stored somewhere else. If not by spring they would be ruined with algae. Then there is the cleaning of the pads and replacing them every so often.
It is a novel idea to have a swamp cooler and I know when and if I ever get to move out west that is the A/C out there. I just don't have the time or engery to build one right now.
So anybody that does build one please keep us posted as to how it works out.

I have a friend that has one in his orchid greenhouse that he made. I am looking at building one now. I haven't gotten the instructions from him yet but I do know that he has a small cattle trough instead of a bucket.I have a cooler now but it's too small. They come in different sizes but the larger size I need is 887 bucks. Too much for me! I inherited the other one and my orchids couldn't have survived without it. Even with 63% shadecloth the temps are over a 100. You do hook it up to a vent so the humidity doesn't build up. Surprisingly, I have more trouble in the winter when the heat is on and none in the summer with the cooler. My fan and cooler are hooked up together so that the fan goes off at a certain temp and then the cooler comes on. The cooler is hooked to it's own vent.

I built one with the box fan blowing onto the pad. Swamp cooler replacement pumps are under $15. I used a couple window planters for my water reservoirs, drilling holes in the top one. The pump just barely fit in the bottom. The pads were a couple cheap furnace filters. It was all built on a 1x8 frame that screwed to the front of the fan. I could remove the entire gadet with fan as a unit.

Biggest problems- the filter/pad was too close at only about 7" away, so the air would redirect the water flow, and it became a catch the drip game. The filter, once wet, blocked a lot of air flow, so wherever the padding was thinnest, water came out with more force. This eventually emptied the system of water. My filter holding system of baling wire was a bad idea, too.

I didn't find it very effective. It just didn't move much air, the fan alone seemed to work better. Maybe with a deeper box it would be better. Box fans aren't designed to push air well, that's why you see squirrel cage fans in the commercial units. Leaks were hard to control. The filters were always rearranging themselves.

Eliminate my errors, you might have a good design! ;-)

-Ed

Hey Cactus You can get coolers that are self-contained.
Pumps and all. 25ft for $1300.00 plus the vent of course.
add another $1200.00.

There is a company called air-n-water that sells an evaporative cooler for $299 that is speced at 5000btu/hr with an input power of 210 watts. They are listing it at 200-250 sq. ft. for coverage and 2800 cfm flow. The link is included below. There is another unit listed for a similar price but there was no spec sheet available.

Here is a link that might be useful: Convair Evaporative Cooler