Outdoor Misting Fan and Misting Systems

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Cooling by evaporation

The principle of cooling by evaporation is a trick used by animals. For example, we sweat when it gets hot. The sweat on our skin evaporates, but as it does so, it absorbs a little bit of the ambient energy in the air, cooling it in the process. The effect is very pronounced when you rub a little rubbing alcohol on the skin, causing it to cool down noticeably.

Animals do it too, but not always with sweat glands like us. Dogs don't have sweat glands, but they have these big sloppy tongues which hang out during hot times. Moisture evaporating from the dog's tongue causes the ambient air to cool down also, drawing heat away from the dog. There are two kinds of ways to use evaporative cooling: the misting system and the outdoor misting fan.

The misting system

Interlacing a series of tubing into the shade structure or the porch ceiling directly, and connecting it directly to the water supply, a misting system supplies a fine spray of water over the shaded area. The fine mist is aerosolized droplets of liquid water. Because it's still a liquid, it can evaporate, either while its in the air or after it's landed on a surface. Evaporation results in cooling of the surface or the area being misted. A pump module pressurizes the water, and the choice of nozzle determines how fine the mist is. The set-up is considerable, requiring connecting tubing to the pressure pump, and then arranging the tubing, as well as affixing nozzles to their respective final locations.

The outdoor misting fan

An outdoor misting fan overcomes some of the set-up problems of the misting system. A regular-looking fan has a nozzle in its center face. The nozzle is attached to a high pressure pump, which sprays water out the front of the fan. As the water comes out, it's additionally propelled and carried by the current of the fan. The misting fan has slightly more portability. The set-up is less intensive. However, the area covered is not as wide as a well set-up misting system because the fan is a single nozzle.

The portable misting fan

A disadvantage of both misting systems and outdoor misting fans is that they must be attached to a water supply using hoses and tubing. Manufacturers have overcome this problem with portable misting fans. Portable misting fans have a self-contained water reservoir. Because the mist is made up of such fine droplets, even a small reservoir contains enough water for about 5 hours of continuous misting. The fan still needs to be plugged into an electrical outlet. There is a considerable amount of water in some of these units (up to 10 gallons), so transportation of the unit must be facilitated with wheels.

Costs

Both the misting system and the outdoor misting fan are expensive, in the hundreds to low thousand dollar range. Different nozzle sizes might be required depending how the range of humidity your area experiences. The more humid it is, the more difficult it would be for evaporation to happen. The way to ensure evaporation is to have small droplet sizes. So in humid areas, nozzles with a finer mist are needed. Whereas in dry or desert areas, nozzles with larger droplets will work fine.