Abstract: In one aspect, a heat exchange apparatus is disclosed having a liquid distribution system configured to distribute liquid onto a liquid absorbent material and an airflow generator operable to cause air to flow through the liquid absorbent material and toward an indirect heat exchanger. The heat exchange apparatus includes a controller configured to operate in a dry mode where the controller inhibits the liquid distribution system from distributing liquid onto the liquid absorbent material and a wet mode where the controller causes the liquid distribution system to distribute liquid onto the liquid absorbent material. The controller is further configured to operate at least one of the liquid distribution system and the airflow generator to inhibit drift of liquid from the liquid absorbent material toward the indirect heat exchanger in response to the controller switching from the dry mode to the wet mode.