What is the most common HVAC system?

The most common HVAC system is a split system, which consists of an outdoor unit and an indoor unit. The outdoor unit contains the condenser, compressor, and fan, while the indoor unit contains the evaporator and fan. The outdoor unit is responsible for removing heat from the air, while the indoor unit is responsible for distributing the cooled air throughout the space. Split systems are the most popular type of HVAC system due to their efficiency, cost-effectiveness, and ease of installation. They are also highly customizable, allowing for a variety of configurations to meet the needs of any space.