What is the most common pump in HVAC?

The most common pump used in HVAC systems is the centrifugal pump. Centrifugal pumps are used to move fluids, such as water, through a system. They are highly efficient and reliable, and are used in a variety of HVAC applications, including cooling towers, chillers, and air handlers. Centrifugal pumps are also relatively easy to install and maintain, making them a popular choice for HVAC systems.