Draft is divided into which two categories?

Draft is critical to understanding how air flows in various systems, particularly in heating, ventilation, and air conditioning (HVAC). The two categories of draft are natural and mechanical.

Natural draft refers to the movement of air that is caused by buoyancy, where warmer air rises and creates a difference in pressure that draws cooler air inward. This type of draft relies on the natural laws of physics and is typically found in systems where there is no additional equipment required to move air, such as chimneys or vents.

On the other hand, mechanical draft involves the use of fans or blowers to induce air movement. In this case, mechanical means are applied to create airflow, allowing for more control over ventilation and air exchange. This is often utilized in modern HVAC systems where specific air changes are required for comfort and efficiency.

Understanding these two categories of draft is essential for designing systems that effectively manage air quality and thermal comfort in various environments. The other options, while they might relate to airflow in a more general sense, do not accurately categorize draft in the same fundamental way as natural and mechanical do.