Choosing Whether or Not To Install Evaporative Cooling

(Also see “Trouble-Shooting” if your cooler is not performing well)

Evaporative Cooling
Refrigerated Air Conditioning??

A common question asked by many is “should I install an Evaporative Cooler or Refrigerated Air Conditioning?”

(Please note: The correct terminology is “Evaporative Cooler” and NOT “Swamp Cooler”)

If you live in a coastal or tropical region, you probably never hear the explanation below because “evap cooling” is not very efficient when your ambient air is full of humidity.
(except for use in greenhouses where high humidity is healthy for the plants)

If your wet bulb temperature is around 60% and higher, then refrigerated cooling is the correct answer.
In lower wet bulb regions a properly sized evaporative cooler can be a very cost- effective and comfortable choice.

Sizing the evaporative cooler is the key

A good “rule of thumb” is to have 1 air change every 3 minutes in northern states, 1 air change every 2 minutes in the mid section and 1 air change every 1-2 minutes in the southern states.

The Rule of Thumb formula for sizing your cooler is very simple;

Multiply the length by the width by the height of the area to be cooled to get the cubic footage for the area. Then divide by your air change factor minutes. The example below reflects a “2” minute air change.


A home that is 30′ wide, 40′ long and 8′ ceiling has a total of 9600 cubic feet of area to be cooled.
30 x 40 x 8 = 9600
Using the factor two (for an air change every two minutes),
divide 9600 by two to give you the CFM required, in this case, 4800 CFM.
9600 / 2 = 4800

In this case, you would want to use a 4800 CFM cooler.
(Note: It never hurts to go one size up. You might consider a 5500 CFM cooler here)
The cooler can be run on low speed, then cranked up to High on severe days.

Another important factor is “Exhaust Air’. A good cooler design is to exhaust slightly more air than your cooler is supplying, this can be done with windows or doors being open slightly or a sized exhaust fan inter-locked with the cooler.

Having enough air exhausted is important so that there is negative air pressure in the conditioned space, positive air will cut down your blower’s capacity. A big advantage to evap coolers is that the capacity can be changed easily by adjustable pulleys to increase or decrease air flow. If you open your front door and the pressure slams it shut then, you need more exhaust openings, such as a window or another door.

(Ample air exhausted also reduces the humidity build up)

Refrigerated air conditioning cools no matter what the humidity is and usually increases your home value (as well as your electric bill) more than an evap cooler, but with a well designed evaporative cooling system installed, cost is less to install and hardly noticeable on your utility bill.

A few notes for evaporative cooler maintenance:

The more frequent aspen cooler pads are changed the better – don’t try to get 2-3 years out of pads. Twice a season is best (although seldom done). Be sure to change aspen pads at the beginning of each season when starting up your cooler.
(An exception to this is using a cooler with a celdek type pad, such as our UltraCool)
The pads can easily be used for five years or more when the cooler is properly installed with a bleed off system.

A properly installed bleed off system can prolong the life of your pads and greatly reduce the corrosion affects on your cooler. Below are two types that can be used.

Bleed Off Kit System
Power Clean Purge Pump System
(Purge Pump Conserves More Water)

Oil the motor and bearings – Most evaporative cooler motors do have oil ports. Use SAE #20 non-detergent oil.
Do not use motor oil. It has detergent content. This will reduce the life of your bearings.

Check for proper belt tension, and amp draw. (Overloading the amp draw will burn the motor out)

(just a few tips – there are many more things to check out)
This should be done by a qualified technician

Cooler undersized
Replace with larger cooler
Clogged or dirty filters
Replace with new pads
Dry pads or lack of water while cooler is operating
Check water distributing system for possible obstruction in tubing. Check pump operation.
Replace Pump if necessary
Insufficient air discharge openings or inadequate exhaust from area being cooled, causing humidity building up and discomfort

Evaporative coolers must have large enough ductwork
Ductwork sized for refrigeration simply will not let the higher cfm from a cooler out.

Make sure there is adequate provision for exhausting air from area being cooled.
Excessive humidity.
(See also item above re: inadequate exhaust)
In some areas, there may be a few days during the summer when the relative humidity is high, resulting in poor cooling. (60% or higher) These are limitations of an evaporative cooler under conditions of high wet bulb temperature.
Blower turning backwards
Reconnect motor for correct direction.
Blower installed backward
Remove and reinstall blower wheel to turn in correct direction.
Blower running too slow
Check motor amps. If below nameplate amperage, readjust variable pitch motor pulley to increase blower speed. Do not increase amperage above motor rating. This will burn the motor out.

Evaporative Cooler Maintenance

A Breeze For Do-It-Yourselfers

Save money on energy and repair costs, and increase cooling efficiency with this easy Spring cleaning project!

Service Tips for Optimum Cooler Performance

Cooler maintenance is not a difficult task, and can be completed with a minimum of mechanical knowledge and a little assistance. Use this guide and ask for help at your local home improvement center or hardware store where evaporative coolers are sold.

1) Shut off power and water. Essick Air Products, manufacturers of Champion, Ultra Cool, and Tradewinds coolers, cautions that safety is important, so disconnect the power to the cooler and turn off the water supply before attempting any preventative maintenance.

2) Replace pads: Remove side panels and install new evaporative media pads at least twice during the season. Cooler pads become clogged with dust, pollen, mildew and minerals from evaporated water. Dirty media pads reduce cooling efficiency and overwork the motor. Clean debris out of the louvered side panels and water troughs. Call your cooler manufacturer for pad size, or write down the cooler make and model and visit your improvement center for assistance.

3) Clean water reservoir: Remove the cooler overflow/drain tube in the reservoir pan and rinse out standing water, dissolved salts, silt, old pad fibers, etc., with a solution of water and vinegar. If necessary, use a sturdy nylon brush or plastic scraper to loosen deposits. Do not scratch through the protective coating of a metal cooler. A wire brush or metal scraper should only be used on rust spots, and then reseal the pan with spray cooler coating. If you have an easy-care polypropylene cooler, there’s no need to patch and reseal, just rinse out debris.

4) Check water pump: Clean the pump screen of debris and make sure the water pump impeller turns freely. If the pump shaft is stuck, water will not be distributed to pad surfaces, so replace it. Call the cooler manufacturer or visit a retailer for an inexpensive replacement.

5) Check V-belt and oil bearings: Check to see that your V-belt is not cracked or frayed. If so, replace it. Allow about 1-1/2-inch play in belt tension to reduce strain on the motor and blower bearings. To set belt tension, loosen the bolts at the motor cradle, move the motor, then retighten the bolts. Oil the blower wheel bearings on both sides using a 20-weight non-detergent oil. Lift the oil caps and oil slowly until it fills the stem. Don’t overfill! Cooler oil is available in small zoom spout plastic containers to make this easy. Most motors are permanently lubricated but look for oil caps on both ends of the motor, just to be sure.

6) Rotate motor and blower wheel: Turn the blower wheel by hand a few revolutions to spread a thin coat of oil on dry bearing surfaces. If the motor or blower wheel doesn’t turn freely, you may have to replace the motor or call for service.

7) Open dampers: If you have manual slide-in dampers, they are usually located where the cooler is attached to the ductwork and/or at the furnace air handler, or both! Remove any slide-in dampers. If you cannot locate a damper, your cooler probably has a barometric damper that opens automatically. If no air enters the home when the cooler is turned on, call for service, or ask for assistance.

8) Fill cooler, adjust float: Turn on water supply and make sure the float shuts the water off about 1/2-inch below the top of the overflow/drain tube. If the float valve is not working, replace it by purchasing an inexpensive repair kit. If the overflow tube leaks around the gasket, tighten the nut or replace the tube gaskets. If water runs over the tube, adjust the float arm. Check to make sure the cooler is level and there are no leaks.

9) Turn on cooler: Replace side panels, turn cooler on and examine water distribution to make sure water fills the troughs and flows down all pads evenly. If water flow is restricted, remove the panel(s) and clear the blockage by snaking a flexible wire into the tube-end orifice.

10) Control corrosion: The best way to minimize corrosion is to install an inexpensive “bleed-off kit” that continually flushes minerals out of the cooler as it operates. Or add a mineralizing agent neutralizer, or replace the water manually two times a month by draining and refilling the reservoir.

Essick Air Products manufactures both the Tradewinds polypropylene line of UL Approved polypropylene evaporative coolers, as well as the Champion and Essick line of metal coolers that are marketed throughout the Western US. For additional information on evaporative cooler maintenance, refer to Essick Air’s Web site at or call 1-800-643-8341.

About Essick Air Products

Essick Air Products/Champion Cooler Corporation was founded in 1943 in Little Rock, Arkansas, and today is one of the largest and leading evaporative cooler manufacturers in the country. The company has been owned by Walton Enterprises since 1978 and operates manufacturing facilities in Arkansas and Texas. Essick is the only company that manufactures both metal and polypropylene coolers due to varying customer needs and interest.