Humidification Systems

Humidification can take place within the air conditioners, or by stand-alone units. In some data centers, it might be better to introduce moisture directly into the room where it will mix easily with the ambient temperatures . This can be done with individual humidifiers, separate from the HVAC units. These should be units designed to keep the psychrometric rates of change to a narrow margin, monitor the room conditions, and adapt to the current room and equipment demands. Separate units throughout the room increase the amount of control over humidification and offer redundancy.

HVAC units are available with the capability of adding moisture to the air flow, but they might not be the best solution due to the way they do this. Possible problems with introducing moisture directly to air within the HVAC units are:

Cold air flows cannot accept high levels of moisture, so the moisture will condense.
Condensation can form within the process coolers and cause corrosion, reducing the operational life of the units.
Condensation can create water buildup and spills.
HVAC units that introduce cooling air into the subfloor mix moisture with cold air that might be near saturation. This can cause condensation and corrosion within the subfloor system.

However, separate humidifier and HVAC systems will be more expensive than containing the humidifier in the HVAC unit itself. Separate units will also add to labor costs. The placement of RH systems out under the raised floor will require water, in either pipes or bottled form, to be within the data center so the same precautions must be taken as with pipes that are in the data center space. As you can see, there is no right answer. Each approach has its advantages and disadvantages. You must determine what is the correct solution for your data center.

A recommended humidification system, available as a separate unit or as part of an HVAC unit, uses a closed water bottle that contains electrodes to heat the contained water and produce steam . The closed bottle design removes any suspended contaminant particles from the supply water resulting in clean output. Also, ultrasonic humidifiers might be an effective choice.

Whatever system is chosen , carefully consider redundancy to ensure that the humidification needs of the room are met without serious disruption.