With the introduction of rigid evaporative media, modern direct evaporative air coolers (EAC) can now provide trouble free service in a wide range of challenging applications for both cooling and humidification. Rigid media has predicable performance, long service life and high operating velocities. The inherent low energy usage makes them even more attractive.

When discussing the maintenance of these simple devices, it is necessary to look at the total picture: the evaporative process, water chemistry, control schemes and design features. This paper will review the operation of evaporative coolers including the evaporative process, water usage, and the interaction of various water qualities. Suggestions will be made for important design features and control schemes that minimize scaling, biological contamination and media failure.

A case study of units used for winter humidification and summer cooling will demonstrate how a large industrial user, developed best practices for their coolers that run 24/7. This case study will show how media life has been extended more than 3 times any of their previous experiences.