System — a system needs to be a high pressure misting system to work effectively. High pressure systems create water particles that are sized to efficiently evaporate. Low-pressure or mid-pressure systems will typically create wetting because the water particles are too large to evaporate and they simply fall to the ground. Note: nozzles should also be sized to the environment (arid vs. humid).
Environmental factors — temperature and humidity are the key. The more humid, the less water you can effectively evaporate. The less humid, the more water you can evaporate. Time of day plays into this as well. Generally speaking the hottest time of the day is the least humid.
Structural factors — how is the misting system placed relative to the surroundings. Are the nozzles mounted up high? The higher the structure the more time that the mist has to evaporate before falling to the ground. If you are using fans you will want to make sure that the “throw” and “spread” are appropriate for the application. We use vastly different fans in agricultural applications than we do in commercial applications.
Use — there is a difference between using a misting fan to refresh guests at an amusement park and a misting fan placed over diners at a restaurant. At an amusement park you will often see guests walking right up to the fan — almost as if it were an interactive exhibit. They don’t mind if they get wet. At a restaurant, on the other hand, nobody wants to get wet.

Last note – quality is an important factor and often overlooked. Our industry is not as mature as other equipment such as air conditioners, water softeners or pool equipment. The mist may look the same when you first turn a system on but there is a huge difference in the quality of the high-pressure misting pumps, their internal components, the misting line, nozzles, fittings, fasteners and so on. Buyer beware!

Signed

fogman