Evaporative Coolers

An air cooler contrasts with an air conditioning system and works using a completely different principle. Evaporative coolers are most effective when they are not in a closed space—a feature where they differ from air conditioning systems. This makes the devices ideal for use in hot, dry outdoor conditions. Still, energy efficiency and silence continue to be features of these machines, and they are often available at a fraction of the price of air conditioning units.

The natural process of water evaporation is used to make air temperature lower in evaporative coolers. Water absorbs heat in the evaporation process, which is the liquid changing into a gas. The "cooler" pulls warm outside air through moisture-laden pads. As the air passes through the pads, the water in the pads evaporates, drawing heat out of the air and cooling it. The cooled air is then blown into the living space. An evaporative cooler will reduce the hottest temperature outside by about 20°F.

Evaporative coolers perform optimally in hot, arid climates that feature low humidity. The best regions for this type of cooling system include the southwestern United States, some areas of Australia, and certain localities in the Middle East. Oceanic or tropical parts of the world where humidity is consistently high are the very places where these coolers are least effective. Conversely, the dry heat of the desert is where evaporative coolers deliver their best performance.

Compared to traditional air conditioners, evaporative coolers use considerably less energy. They have a much smaller environmental footprint because they do not use harmful refrigerants and consume very little electricity. Added to this, they also add moisture to the air, which can be downright beneficial in certain applications—like in the arid climate of western Albuquerque, where even the slightest elevation of humidity can help reduce the space's temperature to a comfortable level. Then there's the cost issue, which has a downside to it: Evaporative coolers are much cheaper to buy than traditional air conditioners, and they are far less expensive to operate.

Evaporative coolers consume varying amounts of water, depending on their size and the surrounding environmental conditions. While smaller residential units may use only 3 to 10 gallons of water per day, larger, industrial-type units use much more. Water consumption also depends on several factors, including the temperature and humidity of the environment in which the cooler is located and how often the unit is operated. Despite the potential for large water usage, many modern coolers feature water conservation mechanisms to cut down on waste.

Indoor use of evaporative coolers is possible, but for them to work effectively, adequate ventilation is needed. Operating a swamp cooler in a closed space can lead to excessive humidity buildup, as these devices cool air by adding moisture to it. The coolers work best in conditions where the air...

To ensure that evaporative coolers operate well and last a long time, they need maintenance. This means occasionally cleaning or changing the water-saturated pads that cool the air, seen in the photo with the cover removed. It also means checking and cleaning the water distribution system, seen in the next photo, and inspecting the pump and fan. In desert areas, the unit is likely to get dusty; it's best to cover it during the off-season. The same is likely true for a unit mounted in an unheated part of an attic. Any annual service call should include a good inspection of the system.

The essential distinction between an air conditioner and an evaporative cooler is in how each one cools the air and the energy efficiency of each. Air conditioners use a refrigerant that's very cold and very low in pressure to cool the air and remove almost all of the humidity. Evaporative coolers, on the other hand, cool the air by making it pass over wet pads. This is not a refrigerant. This is water that's evaporating, and this process lowers the temperature of the air. The E.C. does use energy. In fact, we've been frequently saying that the E.C. is energy efficient. But you're going to see why that's such a loaded statement.

The auditory output from evaporative coolers differs from model to model and even within a single model, depending on its size; for instance, smaller residential air coolers tend to be quiet, with few producing sound levels you wouldn’t expect from a typical fan. That said, some industrial-grade models might ramp up the volume and nonetheless be more energy-efficient cooling a spacious, open area than an AC unit.

Commercial and industrial evaporative coolers are found in warehouses, factories, and farming operations all over the United States. These types of coolers are good at refreshing huge, open workspaces. In places where air conditioning is impractical or costly, these very cool coolers do their thing. Compared to residential units, commercial units are just way cooler, literally and figuratively. These evaporative coolers can even be used in places where air circulation is good and humidity is low.