HVAC stands for Heating, Ventilation, and Air Conditioning. It is a system that is used to regulate the temperature, humidity, and air quality of a space. In heating, HVAC systems use a combination of heating elements such as furnaces, boilers, and heat pumps to generate and distribute heat throughout the space. The system also uses air ducts to circulate the heated air and vents to release it into the space. Additionally, HVAC systems can be used to control the humidity levels in the space by using dehumidifiers and humidifiers.