Swamp coolers have nothing to do with the swampy wetlands of Louisiana and no alligators are involved. Rather, swamp coolers, also called evaporative or wet air coolers, are effective and cost-efficient air-cooling devices. They are highly suitable for use in drier climates and are found in a wide range of residential, commercial and industrial applications.
What is a Swamp Cooler?
An industrial evaporative cooler, also known as a swamp cooler, lowers air temperature by blowing air over and through water, using the process of evaporation, and then circulating that cooled air throughout a room or building. It works like the human body’s cooling system, where perspiration is secreted and warmer air causes evaporation, thus reducing the body’s temperature. Think about how someone feels when emerging from a swimming pool on a warm day and a breeze evaporates water on the skin.
Evaporative cooling can be used in an individual room, in a whole house system or a very large commercial or industrial application. It works because water can absorb a large amount of heat in order to evaporate.
Evaporative cooling is as old as the ancient Egyptians and as modern as today. It differs from typical air conditioning, which works by passing air over coils that are filled with a refrigerant. The cooled air is circulated through the building and heated air is vented to the outside.
How Does One Work?
The parts of a swamp cooler, and how they typically operate, are:
Water supply. Water must be connected from the home or commercial building’s plumbing to the swamp cooler.
Inside the swamp cooler, or swamp box, there will be a cooler float on the bottom of the box. The float controls the amount of water in the box. When adequate water is present, the float rises and shuts off the water, preventing overflow.
A pump motor inside the box pumps water from the bottom of the box through the water lines to wet the evaporative pads.
Evaporative pads. Pads line the inside of the box. They are made of a fluted material that absorbs water and is treated to avoid rot.
Blower and blower motor. These work to pull warm air across the evaporative pads into the swamp cooler. In this way, the moisture cools the air and cleans it. The blower then forces the cooler air through the ductwork and vents it into the space to be cooled.
Swamp coolers are “open systems,” meaning that they rely on the flow of air. The cooled air must have “a way out;” the cooled air must displace air already inside the space. That means that it is important to have a window or vent opening to direct and displace the air.
Keys to successfully operate a swamp cooler are:
Operate the cooler when the outside humidity is relatively low—a dew point under 55 degrees.
Open a window or vent to let the air out at the same rate that the swamp cooler is blowing air in.
The fan option can be used to circulate air if the inside temperature is already acceptable.
Increase the fan speed to increase the cooling factor.
A key question is “where will a swamp cooler be effective?” The answer is simple—in a climate that is typically hot and dry, not one that is humid. That is because the evaporation process won’t work well if the outside air has too much moisture content. Areas of the United States where swamp coolers are typically found are the Southwestern states of California, Western Texas, Nevada, Arizona and New Mexico. Swamp coolers are also used in the semi-arid states of Utah, Wyoming, Montana, Idaho, Washington and Oregon.
Even in areas where swamp coolers make great sense, there may be periods of high humidity where they won’t function well, such as the “monsoon season” in New Mexico and Arizona during July and August.
So, how do I pick the right swamp cooler? Here are suggested considerations for selecting a residential swamp cooler. A company that is an expert in evaporative cooling should be consulted for situations requiring an industrial swamp cooler. For residential uses:
Choose between a window-mounted roof-mounted or ground-mounted unit. A window-mounted unit will only cool a room or two. A roof-mounted unit is more efficient but more difficult to install. A ground-mounted unit will offer easier maintenance access.
Choose a unit that has enough blowing power to cool the entire house. Also, consider the capacity of the ductwork that will carry the air.
Get a unit that has an air filter to reduce dust and counteract allergens that may get pulled in from the outside.
Beyond their commonly recognized residential uses, evaporative cooling, in dry climates, offers great applications in industrial plants, greenhouses, warehouses, factories, commercial kitchens, laundries and dry cleaners, and many more situations.
Are They Energy-Efficient?
The answer is a resounding “yes.” They are relatively inexpensive to build and install. More importantly, the monthly operating costs can be about one-third of traditional air conditioning due to the reduced drain on electricity. They use about 15 to 35 percent of the electricity needed by a similar size air conditioning system. And, they require no chemicals as does traditional air conditioning, so they are better for the environment. Both swamp coolers and air conditioners require maintenance, but an air conditioning unit is more complex, so repairs can be more costly.
Swamp coolers offer loads of benefits. However, the climate or operating conditions need to match the dry climate applications that make them a good fit. The operation is simple, the principle of evaporation intuitive and they perform both effectively and efficiently. Consider this benefit summary:
Provide effective cooling
Add moisture to dry air
Less costly to run
Less costly to maintain