There are many approaches to controlling humidity in a data center. The first decision is where to control it from, e.g., at the local computer room air conditioning (CRAC) units or centrally at the makeup/pressurization AHUs. Consideration must then be given to the type of humidification system to use. Spray pads, ultrasonic, steam, and infrared systems have all been used in critical applications with varying degrees of success.
One of the most important factors in regulating humidity is proper sealing of the room and installation of an appropriate vapor barrier. Without a vapor barrier, it may be nearly impossible to add or remove enough moisture to precisely control the interior environment. This article will examine all of the above, plus control schemes, safeties, and lessons learned.