This article was written to identify the different types of types of cooling equipment and identify their strengths and weaknesses so that you can make an informed choice based on your needs. There are six basic types of liquid cooling systems: The simplest of these systems is a liquid-to-liquid cooling system. This system consists of three main pieces of equipment: the recirculating water pump (s), the heat exchanger (s), and the cooling tower. Open recirculation cooling systems feature “wet towers,” where cooling water comes in direct contact with upward airflow. Water from the heat exchanger is pumped evenly over the top deck of the cooling tower.