Couple questions

1. Where are the plans/schematics?

2. How much water does it use?

Good job

TedH,
Great idea! I am in the tropics and heat here is a given. I've been thinking of solutions to the heat prooblem here too.

You have reinvented the adiabatic swamp cooler.

Careful with the salts that you'll get on the wetted media as you operate it.

Hi Okami-

Couple questions

1. Where are the plans/schematics?

In researching evap cooling I found a simple design at
http://h2othouse.com/html/evap-coolers.html; the only change I made was to enclose the spray bar in roof flashing, as it controls the spray from shooting out the back of the device; if you build one, use the smallest drill bit you can get for the spray holes & space them about every 3/8"; these is also an excellent article at http://edis.ifas.ufl.edu/BODY_AE069;

2. How much water does it use?

It "seems" to use about 1-2 quarts every half hour it is running, but I think the hotter & less humid it gets the evaporation rate will rise; (I installed a swamp cooler float valve to add water to the tank last year as I found that during periods of extremely hot weather almost one-half (15 gallons!) of my nutrient water evaporated per day) so that water replacement due to evaporation is already covered.

Hi willard3-

I'm not sure I'd describe it as a adiabatic cooler, as my understanding of an adiabatic system is a system that doesn't gain or lose heat energy; my little evap cooler is exothermic in that the system should loose 8400 BTU for every gallon of water that is evaporated; having never played around with an evaporative cooler before, I was trying to lower the air temperature in the greenhouse, and the immediate drop in the water temperature was a surprise; I am somewhat concerned about the wetting agent used in the pad, as soon as I find a source of plastic pads I'll change the pad; as to nutrient salts build up I'll just have to see how that plays out;

Here is a link that might be useful: Schematic of homemade evap cooler

Manila - you might not get as good an effect in your area. When you have high relative humidity you will only get maybe a 5-8 degree drop in temperature, wheras in dry areas like Arizona you can get a 20 degree drop.

some points to consider are:
1.if you move the pad a foot downstream from the fan it will help prevent moisture on the rather exposed windings in the motor
2. a box fan is a propeller which when loaded or restricted in air flow draws more current or loads up. A squirel cage fan is the opposite when restricting air flow it unloads or draws less current. Most comercial swampers are made with squirel cage fans. You may be able to find a junk fan from an old furnace for close to or nothing.
3. do you realy want to cool the nutrient?my understanding of plants is that if possible warmer nutrients produce faster growth.
4. beware of PPm of the nutrients as you stated you have added makeup water to offset this but most makeup water also contains minerals which you are now concentrating. Most comercial swampers also include a bit of overflow or wasting to help prevent mineral buildup which inhibits evaporation and clogs equipment. this is generally done by a unique balance in fill and overflow so that when it shuts off the remaining water in the lines and pads causes an overflow. when it starts the water leval drops to fill lines and pad causing fill valve to act.
5. The point has already been made and is correct evaporative cooling only works in dry air the effectiveness will be proportional to how dry the air is.

I wonder if a better plan may be to run a swamp unit independant of your nutrient solution and if needed run the nutes through a loop in the pan of the cooler for some cooling without the addition of larger amounts of makeup water to the nutrients to allow for the evaporation. This would also allow some blowdown of mineral saturated swamp unit water without loosing nutrients or upsetting the mineral balance there.I would also question the need for cooling nutrients unless they are over 80 degrees. At any rate watch your ppm close while using until you get the kinks worked out. Sounds like a good idea in general as swamp cooling is about the only method feasable in greenhouses and most plants deal with higher than ambient humudity fairly well. Another option is shading in hot and summer climates most plants get more sun than they can use so partial shading may also reduce heat without loss in growth.

This is a great idea. My tomatoes suffered severely last year due to the heat  even when I shaded them.

I know it has been a while since this was posted, but, i wonder if anyone out there could offer info in regards to where to find the padding shown in the photos? OR, if anyone can tell me where to find a plastic foam padding for evaporative coolers, I found some in a n unclaimed freight place a while back, it was on 4' wide rolls, but have not been successfull in locating a dealer, ty, jeanie65

There is one variable you need to be aware of and that is relative humidity (RH). The efficiency of evaporative cooler is highly dependent on your RH. There is an inverse relationship between evaporative cooler efficiency and RH. It would not be very effective in my area where my RH is 80%. However if your RH is say 30% it might make sense. See the psychometric chart below.

That is very good information, Hank. I guess that is why you see swamp coolers for houses in the desert & hot dry areas. I never heard of them when I lived in a humid climate.

You can buy several kinds of evap air cond pads at home depot or lowes. I have hung a door sized pad on the door of my greenhouse, with fans blowing out windows on the other side, and then just run water over the pad with a hose at intervals. Works fine for the few really hot days we have, as long as I am home for them, anyway.