A rooftop unit (RTU) is a self-contained HVAC system that is installed on the roof of a building. It is typically used to provide air conditioning, heating, and ventilation for commercial and industrial buildings. An RTU typically consists of an outdoor unit, an indoor unit, and a control system. The outdoor unit is responsible for providing the conditioned air, while the indoor unit is responsible for distributing the air throughout the building. The control system is responsible for controlling the temperature, humidity, and air flow within the building. RTUs are designed to be energy efficient and cost effective, and they are often used in buildings that have limited space for traditional HVAC systems. RTUs are also easy to install and maintain, making them a popular choice for many businesses.