Residents living in hot climates with low humidity levels can benefit tremendously from a swamp cooler. As an alternative to a traditional air conditioning system, a swamp cooler uses a more refined concept of the simple, low-technology process of evaporation to provide cooling comfort. Moreover, swamp coolers are extremely energy efficient and can cost-effectively lower an area's ambient temperature by several degrees.
How they work:
The evaporation process is simple: when water evaporates, a large amount of heat from surroundings is absorbed. This is easily observed when you splash water onto your skin on a hot day, as this results in a cooling - almost chilling - sensation because of the rapid evaporation of moisture on the skin.
With that said, swamp coolers aren't recent inventions. Swamp coolers have been used since antiquity, and civilizations throughout the ages have ingeniously utilized the power of evaporation to keep cool in hot regions. The ancient Egyptians discovered that hot, dry breezes became moist and cool when blown through moist mats or past clay pots full of water, while the Ancient Greeks and Romans also used this principle of evaporation to quell hot temperatures.
Although modern-day swamp coolers are a bit more complicated than water soaked mats, the cooling method remains the same. Swamp coolers utilize a combination of simple technology and electric power to create cold airflow. A large box with a fan is surrounded by wet pads, while a pump continuously circulates water to keep these pads wet. Thus, a swamp cooler both cools the air and makes it more pleasant by adding moisture. Moreover, unlike air conditioners which circulate air over and over, swamp coolers constantly bring in fresh air from outside.
Nevertheless, despite these benefits, there are a few admonitions associated with evaporative coolers, and choosing the wrong type of air cooler will not result in sufficient cooling. Don't make the following mistake when shopping for a swamp cooler:
Don't purchase the wrong type of cooler for your environment.
Although evaporative coolers are energy-efficient and affordable cooling devices, they're only suitable in certain environments, particularly in areas where temperatures rise above 80° F and humidity levels below 50%. As such, they're ill-suited for humid environments because as the outside humidity increases, the swamp cooler's efficiency decreases.
Using a swamp cooler in a humid climate will result in very little water to be evaporated, and in turn, the outside air will almost be the same temperature as the air that has already passed through the unit. Moreover, excess humidity accelerates corrosion and rust.
Don't forget to correctly size your swamp cooler!
Measuring the size of an evaporative cooler is different from sizing a portable air conditioner. Unlike portable ACs which are sized according to BTU ratings, the size of a swamp cooler is actually measured in cubic feet per minute, or CFM. CFMs determine the number of cubic feet of air a swamp cooler can move in a minute, and most manufacturers will recommend that a properly sized unit be able to change the air in a home or workplace 20 to 40 times per hour. Also, unlike portable air conditioners, there's actually no harm in purchasing a swamp cooler that has a slightly greater cooling capacity than your room's requirements.
The easiest way to calculate CFM requirements is to figure out the cubic feet of the space being cooled and dividing that number by two. The resulting number will give you an approximate CFM rating for a proper-sized swamp cooler. For example, if you have to cool a 150 square foot room with 7-foot high ceilings, you would calculate CFMs as such:
150 x 7 = 1050 cubic feet
1050 / 2 = 525
CFM Needed = 525 CFM
Therefore, with the above dimensions, you would need a swamp cooler that offers at least 525 CFM.
Don't expect extreme temperature changes.
Remember: swamp coolers are effective alternatives to standard air conditioners in arid climates, but keep in mind that swamp coolers do have limitations when it comes to temperature changes.
Generally speaking, a standard home air cooler will only be able to reduce the ambient temperature in a room by 10 to 20 degrees Fahrenheit. As such, they are not capable of controlling an area's complete temperature. Furthermore, an evaporative cooler's effectiveness will greatly depend on two factors: the outside temperature and humidity level. For optimal cooling effects, a swamp cooler will work best in the hottest time of the day and when humidity levels are below 50% (the lower the humidity, the better).
The chart below provides an approximation of temperature changes delivered by a swamp cooler:
Provide sufficient exhaust for the unit.
Evaporative coolers don't require venting like portable ACs, but the air forced out will still require an exit path in order to ensure sufficient cooling (this can usually be accomplished with an open door or window). Moreover, if a swamp cooler does not utilize an exhaust duct, it will require enough space for sufficient exhaust and airflow, and this should be taken into consideration before making your purchase. As a general rule, allow a 2 foot square opening for each 1,000 CFM provided by the swamp cooler.